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Описание

MANAGEMENT OF
REFRACTIVE ERRORS AND
PRESCRIPTION OF SPECTACLES

MANAGEMENT OF
REFRACTIVE ERRORS AND
PRESCRIPTION OF SPECTACLES
Yogesh Shukla
MS (Ophthalmology)
Professor
National Institute of Medical Sciences
Jaipur, Rajasthan, India
Fellowship, Anterior Segment
Eye Foundation of America
West Virginia, USA
Fellowship, Pediatric Ophthalmology and Strabismus
Johns Hopkins University Hospital, USA
Director
Rajasthan Nursing Home and Eye Center
Jaipur, Rajasthan, India
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Management of Refractive Errors and Prescription of Spectacles
First Edition: 2015
ISBN: 978-93-5152-884-5
Printed at:

Dedicated to
My parents,
who brought me in this world;
so that I could write this book
to help millions of visually impaired

Preface
This book is for the clinicians. Both for the learning and the learned
ones!
Its aim is to sharpen the judgment and skills. And its goal is to
increase the yield of satisfied patients.
It is really disturbing and unfortunate that with the development
of subspecialties, we have lost touch with many basics of
ophthalmology, gone casual on many aspects, and the so-called
superspecialists in ophthalmology, consider dealing in basics as
demeaning. One of such areas is refraction and treating refractive
errors. So much so that, I have encountered patients lamenting that
they were been sent to an optician for spectacle correction as the
ophthalmologist is very busy for such a small work !
According to very recent studies, 800 million to 2.3 billion people
are affected by refractive errors worldwide. Myopia tops the list,
with 80–90% of population suffering in some countries of Asia. This
mammoth prevalence of refractive errors, speaks for itself about the
ocular disorder. And to add salt to the injury, the incidence of these
errors, particularly myopia, is on the rise.
Proper evaluation of refractive errors and spectacle prescription
are and will remain an integral part of ophthalmic practice.
In a general eye hospital, almost 90% of patients come with
complaints of defective vision, whether due to actual refractive
errors or errors induced by diseases of eyes. Even a patient with
early cataract can be very suitably corrected with spectacles
and continue his daily work for a long-time. And, therefore,
a thorough knowledge as to how to properly correct his induced
refractive error with specs, is paramount.
To meet these ends, the book is laced with clinical points that can
aid in finding the refractive error properly and translating it into the
best possible pair of glasses.
The book is not only a theoretical narration of principles of
refraction, but also enumerates and illustrates a myriad problems

Management of Refractive Errors and Prescription of Spectacles viii
and pitfalls that lie to trap the unwary, the casual and even, at times,
an experienced clinician.
Many a times, it is the fine tuning of the previous prescription
(of some other clinician), which satisfies the disgruntled patient.
Learning these, the book is the hallmark of a skilled refracting
ophthalmologist, one who has mastered the art of prescribing
spectacles!
Though certain relevant refraction tests and procedures are
mentioned or described (which are standard textbook procedures),
the book is not meant to describe the basics of refraction. It is
assumed that the reader has already acquired the basic knowledge
of refraction. The book will further enhance its commitment towards
refraction, the ability to deal with pitfalls and problems faced in
certain patients, and to fine tune his refracting skills.
Also equally important is to have knowledge of the various types
of lenses available in the market, which one to prescribe, suitability
of individual patient, and how to prescribe. The type of frame to be
worn for a particular type of refractive error is also of paramount
importance.
All of these, including the type of lenses to be used, is left to the
fancy of the patient and the whim of the optician.
Therefore, the book will also give an account of what type of
lenses are available in the market, their specific qualities, what is
suitable for a particular refractive error, how to prescribe a particular
type of lens for a particular patient, and more importantly, the type
of frame to be used for optimum comfort to the patient.
A humble, sincere and unbiased effort is made to updаtеthe
clinicians, and to revive his interest in treating refractive errors and
to fine tune his abilities and skills.
Yogesh Shukla

Contents
1. Accommodation 1
•  How to Test Accommodation  3
•  Accommodation and Convergence  5
•  Excessive Accommodation Amplitude  6
•  Accommodation Spasm  6
•  Subnormal Accommodation  9
•  Refractive Errors and Accommodation  10
•  Pearls  12
2. Cycloplegia 13
•  Contraindications  15
•  Some Special Situations  15
•  Qualities of a Cycloplegic Drug  16
•  Cycloplegia and Glaucoma  20
•  Clinical Pearls  21
3. Hyperopia 23
•  Etiopathogenesis  24
•  Children  25
•  Presbyopia  30
•  Intermediate Vision  31
4. Myopia 33
•  Causes and Progression of Myopia  34
•  Classification  35
•  Management  36
•  Quasi-Myopia  40
•  Unilateral Myopia  41
•  Pseudomyopia  42
•  Night Myopia  45
•  Presbyopia and Myopia  46
•  Pathological Myopia  47
5. Astigmatism 49
•  Prescriptions  49
•  Ciliary Overtures  54
•  Bifocals in Astigmatism  55
•  Irregular Astigmatism  57

Management of Refractive Errors and Prescription of Spectaclesx
6. Presbyopia 60
•  How to Determine near Correction?  62
•  Bifocals in Children  63
•  Near Correction in Adults  64
•  Bifocals in Presbyopia  65
•  Bifocals for Reading in Bed  68
•  Presbyopia and Contact Lenses  68
•  Presbyopia in Myope  69
7. Anisometropia and Antimetropia 74
•  Symptomatology of Anisometropia  75
•  Aniseikonia  76
•  Antimetropia  78
•  Anisophoria  81
•  Correction in Vertical Gaze  82
•  Anisometropia in Children  85
8. Aphakia 92
•  Monocular Aphakia  92
•  The Bilateral Aphake  93
•  Spectacle Management in Aphakia  94
•  Refracting an Aphake  96
9. Pseudophakia 98
•  Monocular Pseudophakia  98
•  Bilateral Pseudophakia  99
•  Unusual Cases  100
•  Pseudophakia in Children  102

10. Medical Problems and Refractive Error 104
•  Effect of Change in Size or Shape of Eye  105
•  Glaucoma  105
•  Changes in Cornea  105
•  Crystalline Lens  106
•  Ocular Media and Lens  106
•  Changes in Accommodation  106
•  Ocular Asthenopia as a Part of Illness  107

11. The Legacy of Spectacles 109
•  History  109
•  Lenses  110
•  Modern Lenses  111
•  Plastic Lenses  112
•  Polycarbonate  113

Contents xi

12. Types and Quality of Lenses 114
•  Refractive Index  114
•  Density  115
•  Abbe Number  115
•  UV Cut-off  116
•  Curve Variation Factor  116
•  Lens Materials  117
•  Summary  119
•  Absorptive Lenses  120
•  Progressive Power Lenses  126

13. Prescription of Spectacles 129
•  Weight, Thickness and Warpage  130
•  Decentrations  130
•  Pantoscopic Tilt of Frames  132
•  Spectacle Fitting in Children  133
•  Frames of Spectacles  134

14. Psychodynamics of Spectacles 138
•  Ocular Neurosis  140
•  The Doctor-Patient Rapport  141

15. The Visually Handicapped 143
•  Reasoning for Success Management  144
•  Examination and Refraction  146
•  Determining the Best Aid  146
•  Optical Aids  147
Index 151

Introduction
In my spare time, I often look-up to a quote that says, “It is a terrible
thing to see and have no vision.” It is a quote from a woman whom we
all know  and love—Hellen  Keller. She was  an inspirational  woman, 
who taught  the world  to respect  people who are blind!  Her mission 
obviously came from her own life, when she became terribly ill at the
age of 2 years, and lost both—her vision and hearing.
 We  are very  blessed  to have  the gift of vision  and need  to embrace 
life to the fullest.
The above paragraph comes in context of how people in this
world are getting needlessly visually handicapped and some even
blind, for very simple reasons such as uncorrected refractive errors.
A prominent example is amblyopia, almost 5% of population is
visually  handicapped  because of amblyopia.  Refractive errors are 
and will remain a major field where eyecare physicians must properly
understand each refractive error as each patient may be different,
and acquire skills of refraction, especially in young children.
As already stated, global refractive errors have been estimated to
affect  800 million  to 2.3  billion  people  worldwide.  In a recent  WHO 
update, 265 million people are visually impaired (including all causes
affecting vision); 245 million have severe visual impairment (visually
handicapped) and 39 million are blind. Among the major causes of
impaired vision, 43% is due to ‘uncorrected refractive errors’, and
33% due to cataract. Such a magnitude of uncorrected refractive errors
demand a serious and sincere attention, which has unfortunately
waned in the recent years.
You will everyday come across patients who have wandered to
quite few doctors but remained unhappy with their glasses. There
is your  test. Dealing  conscientiously  with these  patients  and fine 
tuning their previous refractions to their satisfaction, will bring out
your clinical acumen and the patient will bless you for whole life.
In this reference, before embarking on the examination of the
patient,  remember  some tips, as how  to proceed.  Firstly, take a pro-
per history as to the actual complaints of the patients, some may be
relevant while others irrelevant. Ocular asthenopic problems are wide

Management of Refractive Errors and Prescription of Spectacles xiv
and varied, but you have to sort out which may be actually concerned
with eye. One of the most unfortunate things happening in a busy
outdoor is that in patients complaining of headaches, their vision is
first recorded, and finding normal vision of 6/6, they are declared \
fit, as
far their  eyes are concerned,  and promptly  referred to ENT  specialists  
or neurophysicians, for further needful. This is where you fall into t\
he
pit. You will be surprised that a large number of these patients have
real ocular asthenopic symptoms and when you do a cyclo plegic
refraction, a large number of them will reveal a refractive error.
Therefore, the second pearl is that do not ignore the symptoms
and a normal eyesight does not preclude a refractive error! Each and
every such patient must undergo a proper cycloplegic refraction and
also a careful evaluation of muscle balance.
Thirdly, having done a proper examination and refraction and
once a refractive error has been determined, look for the need of
the patient, the age, the type of vocation, the mental make-up, and
his acceptance for glasses. There are of course ‘rules of thumb’, in
prescribing spectacles, but if you have detected astigmatism for
the first time, the patient may not adjust abruptly to a cylindrical
correction, especially if it is more than 1 diopter or the axis is oblique.
In such cases, a gradual increment with time is advisable.
Another pearl: All patients in presbyopic age are usually advised
regular check-up every 2 or 3 years, as spectacle correction increase
with age. If such a patient comes for check-up at the stipulated time
advised, please check the correction, the person is wearing and
enquire about complaints. If he says that he has no complaints, and
he is happy with his present near correction, do not tamper with it.
There are a number of reasons for happiness, these will be dealt in
chapters ahead, and the patient is best left alone advising politely to
come when symptoms ensue.
Much exercise of thought and research has gone into writing of
the book. It does not only have the standard description of refraction
errors and related conditions, but also relevant examples of long
years of clinical practice.
Your journey through the following chapters should be a pleasant
one, where hopefully you will learn and understand the intricacies of
management of refractive errors and will enlighten yourself to the
fine tuning of spectacle correction and become master of spectacles
rather than getting enslaved by the optician.

Accommodation
1
INTRODUCTION
Accommodation is the ability of the eye to increase its power, by
virtue of which, one is able to see clearly from distance to near. The
accommodation is measured in diopters (D).
It is to be understood that accommodation does not only involve
the change in the shape of the crystalline lens and thus its power,
but the mechanism of accommodation also involves the neuro-
muscular effort to accomplish this change in power. Thus, we have
the accommodation ‘effort’ and the accommodation ‘effect’.
The neuromuscular ‘effort’ involves the nerves supplying the
ciliary muscles and the efficiency of the ciliary muscles themselves.
The ‘effect’ is manifested by the change in curvature of the lens and
its capsule.
It is to be further noted that accommodation also involves the
vergence and the size of the pupil. To be precise, the whole ‘near
reflex’, involving accommodation, convergence and miosis, comes
into play to enable us to focus and see clearly at near. You shall see
in the subsequent pages of this chapter, as to how accommodation is
affected in a number of neuromuscular conditions, of which we do

Management of Refractive Errors and Prescription of Spectacles 2
not usually take cognizance. Let us first, become conversant with a
few definitions.
The amplitude of accommodation (AA) is the maximum dioptric
power attainable by an eye.
The range of accommodation is the linear distance over which
the person can maintain clear vision by virtue of accommodation.
This ‘range’ lies between the ‘far point of accommodation’ and
the ‘near point of accommodation’, which simply means that the
range covers between infinity to the closest point where the object
can be seen clearly.
For clinical practical purposes, what is more important is the range
of accommodation rather than the amplitude of accommodation. In
other words, a person may have perfect amplitude of accommodation
to see clearly close to the eye, but he will not be able to maintain
clear vision at this distance for long and ocular fatigue will ensue.
Thus, he will have to hold the object (a book for example) a little
further away, where he is comfortable. Therefore, in prescribing
presbyopic corrections, one should not rely too much on amplitude
measured by a Prince ruler, but at the distance where the patient can
comfortably accommodate for long.
‘Accommodative insufficiency’ is a term implying the inability of
a person to see clearly at near, at the designated age.
‘Accommodative inefficiency’ is the term specifying a person’s
inability to focus quickly from far to near objects. In other words,
there is a time lag in focusing from distance to near.
The accommodative power or the amplitude of accommodation
slowly but surely, decreases with advancing age. But this decrease
does not follow the ‘rule of thumb’ in each case. There are ample
examples, where a person of age 45 or 48 reads comfortably unaided
while others complain of difficulty in seeing at near before 40 years
of age. This wide physiologic variation is baffling sometimes but we
must not forget the interaction of nerves, muscles and the crystalline
lens in the mechanism of accommodation.
Even the authorities in ophthalmology like Duane and Donders’
differed on the amplitude. Donders found it was 4.5 D at age 40,
while Duane found it to be 5.8 D at age 40.

3 Chapter 1: Accommodation
Examining the observations by a number of authorities, and as
measured by Prince ruler, the following guidelines are recommended:
• At age 40—Average amplitude 5.0 D
• At age 44—Average amplitude 4.0 D
• At age 48—Average amplitude 3.0 D.
Below the age of 40 years, add 1.0 D for every 4 years; above
40 years, subtract 1.0 D for every 4 years. For example, at 36, the
average amplitude would be 6.0 D, at 32 it would be 7.0 D.
Similarly, at age 52, average amplitude would be 2.0 D, and at age
of 56, it would be 1.0 D only. To all the above figures up to the age of
50 years, ± 1.0 D should be considered as range.
These figures become more relevant when a person reaches the
presbyopic age. It is then when the actual clinical test of the doctor
comes into effect. Since the amplitude varies so much, a correct age
for bifocals is difficult to predict.
It is more prudent to know the amplitude, range and the near
requirements of the patient, rather than to follow strictly the above
nomogram.
HOW TO TEST ACCOMMODATION
Three most common tests are narrated here. As accommodation
varies from person to person, so does it varies according to the test
performed. It should be kept in mind, that each test is not foolproof
and accurate. Even with the variables kept constant, chances of
error prevail. At best, these give a fair amount of result which can be
incorporated in prescriptions. The tests are performed monocularly.
Near-point Accommodation Method
In an emmetropic patient, the far point is at infinity. The near point
will then be the dioptric equivalent of the maximum accommodative
capability of the patient. In other words, converting the near point
distance into diopters, will be the measure of amplitude. In this test,
the patient views a near target, say N6 type of letters, which is moved
towards the eye. The distance at which it blurs, is noted as the near
point. Suppose the target blurs at 10 cm (0.1 m), then the amplitude

Management of Refractive Errors and Prescription of Spectacles 4
is 10 D. This is based on a standard law of optics where 1 D increase
in power has focal point at 1 m. It we use a larger target, say N8 or N10
size the near point will be closer as the patient will be able to clearly
even at 6 cm. This means that the near point distance alone does not
determine the amplitude. Target size is an important determinant.
The illumination and speed at which the target is brought closer will
also influence the amplitude.
Prince Ruler
In this, a scaled ruler marked with cm, and equivalent diopters,
having a movable target riding on the ruler is used to measure
the amplitude. It is usually 1/2 m in length, having a reading card
mounted on the scale. A +3.0 sphere is usually added to the distance
correction to pull up the range of accommodation to 40 cm.
The patient holds the prince ruler with one end resting on the
nose and slowly moves the reading card towards and away on the
Prince ruler, to locate both the near and far points of accommodation.
The difference between the far point and near point gives the AA in
diopters.
Spherical Add
This test is also performed monocularly. The patient fixates at a
reading card at a convenient distance of 33 cm or 40 cm. Plus lenses
are then added to relax the accommodation until the target blurs.
Minus lenses are then added to stimulate the accommodation, until
the target blurs again. The difference between the maximum plus
and maximum minus gives the amplitude of accommodation.
The first two tests have a major drawback in the sense that
when the object is moved closer, the angular size of image on the
retina increases, and makes the letters easier to read, requiring less
accommodation.
The spherical add method obviates this problem, but it also has a
fallacy. The incorporation of minus 1.0 D to stimulate accommodation
does not actually stimulate 1.0 D of accommodation and addition of
minus 2.0 D stimulates only 1.8 and minus 3.0 D even less.

5 Chapter 1: Accommodation
Because of these inherent deficits, measurements by all these
methods is only close approximates of amplitude.
In my experience and by other authorities, prince ruler is the
recommended tool used for evaluating amplitude.
There are a few clinical pearls to be kept in mind while measuring AA:
• Accommodative amplitude varies with the position of eyes.
With the eyes down in reading position, the amplitude increases
measurably. If evaluation is done in straight gaze position, which
is normally done and the patients most of the activities are for
near, then the patient will be over corrected for near. The patient
may find working range too close with the correction given.
• The amplitude also is greater when the frontal plane of the face
is down, parallel to the floor. This is due to gravitational forward
shifting of lens owing to relaxed zonules when ciliary muscles are
contracting to induce accommodation. The effect can add 0.5 D
to 1.0 D in elderly to even 3.0 D in younger person.
ACCOMMODATION AND CONVERGENCE
Every individual has a fixed neuromuscular relationship between
the amount of accommodation exerted and the accompanying
convergence. This is accommodative–convergence to accommo-
dation (AC/A) ratio.
It is this finely balanced AC/A alliance that keeps the eye in
alignment during all visual tasks at all distances. The alignment
incorporates ‘fusional vergence’ by virtue of which, there is
elasticity in the physiologic bonding between accommodation and
convergence.
These are a few terms which are relevant in context with the
accommodation–convergence relationship. They are more of
academic interest but the clinician must be conversant with them.
‘Relative accommodation’ describes binocular accommodative
function and concerns with the ability to sustain fusion, when
accommodation demands changes. The essence of this is very clear.
In normal physiologic conditions, both eyes accommodate equally
and the demand for convergence and fusion is equally met, but
there are conditions where both eyes do not accommodate equally,
leading convergence and fusion in disarray.

Management of Refractive Errors and Prescription of Spectacles 6
Test for Relative Accommodation
The patients gaze is binocularly fixed on a stationary near target.
Spherical lenses are then simultaneously placed before both eyes till
the target blurs. The maximum plus lens the patient can overcome
to relax accommodation keeping the target clear is called ‘negative
relative accommodation’ and the maximum minus lenses that the
patient can overcome to stimulate accommodation is called ‘positive
relative accommodation’.
EXCESSIVE ACCOMMODATION AMPLITUDE
There are innumerable examples in clinical practice where patients
boast that they can see clearly at near, at even at 50–60 years of age.
Parents, who come for refraction of their children, grumble as
to how come such a small child is requiring glasses while one of
its grandparent is reading newspaper without any glasses! This is a
difficult situation, as the parents may not understand the scientific
oddity behind the grandparents still good near vision.
There are a few clear-cut mechanisms by which the patient has
good uncorrected near vision. Myopes, early nuclear cataracts, early
cortical cataracts (with some clear area having greater diopteric
power), pinhole affect from use of miotics in glaucoma therapy,
are some examples which the clinicians should keep in mind while
giving presbyopic correction.
ACCOMMODATION SPASM
To see clearly at near a person invokes accommodation or relaxes
accommodation to see at far. Some persons, after using their eyes
for long at near work, are unable to relax their accommodation to
view at distance. Over time, this assumes a fixed nature of their
accommodation and presents a ‘pseudomyopia,’ with all the features
of true myopia. Eventually, the patients begins to manifest symptoms
of ocular asthenopia and an excessive near work in this condition,
may result in blurring for near also. This is ‘accommodation spasm’
and refraction in this state, will lead to overestimating a myopic error

7 Chapter 1: Accommodation
or underestimating hyperopic error. Cycloplegic refraction, will
however, uncover the truth.
Accommodation spasm is frequently seen in persons with
psychogenic stress. They are under pressure at school, workplace or
home. Other ailments like spastic colon, duodenal ulcer, or migraine,
is commonly identified in these patients.
Symptoms of this syndrome complex are headaches, blurred
distance vision, abnormally close near point, and most commonly
a fluctuating visual acuity. The hallmark of diagnosis is the marked
difference in manifest and cycloplegic refractions. It would be
understandable that as hyperopes have more accommodation
demand, ciliary spasms should be more common in these patients.
But surprisingly, this is not true. Accommodation spasms are as
common in emmetropes as in byperopes.
When ciliary spasm occurs in a true myope, though uncommon,
it may be easily misread as rapidly increasing myopia. A cycloplegic
refraction again is the best diagnostic tool.
Patients with uncorrected astigmatism tend to make constantly
varying accommodative effort in an attempt to see clearly and
succumb to ciliary spasms.
Management of Accommodation Spasm
Patients with ciliary spasms are not easy to treat but one of the
following can be tried.
Cycloplegia
This is the best and an easy treatment. An appropriate cycloplegic
agent may be used to break the spasm and the patient advised not to
indulge in near work for a few days.
Prescription of Plus Lenses
In a postcycloplegic refraction, the maximum plus tolerated for a
clear distant vision, even if this is fraction of plus found during full
cycloplegic refraction, should be given. Gradually, the spherical
power can be increased in of +0.5 D to +1.0 D, and can be worn for
months or even years.

Management of Refractive Errors and Prescription of Spectacles 8
In Severe Cases
Cycloplegics like cyclopentolate 1%, can be instilled twice daily.
Simultaneously, plus lenses or even bifocals can be prescribed to
ensure clear vision for distance and near. After a period varying from
few weeks to few months, the cycloplegic is discontinued and the
patient continues wearing the distance correction.
Unequal Accommodation
Accommodation amplitudes in the two eyes are usually equal. If a
difference is noticed with glasses, then the difference may be with
refraction done.
A perfect refraction correction means that when two eyes are
working together, the accommodation is equally relaxed in both
eyes. This is known as ‘binocular balancing’ and is one of the most
important and probably least used in routine refractions; a perfectly
balanced refraction provides comfort and satisfaction to the patient.
Following are some useful tests for assessing the binocular
balance. They are simple and quick to perform.
Partial Fogging Method
After giving the correction lenses in the trial from, blur the vision
by inserting +0.75 D in each eye. Instruct the patient to concentrate
on the line he is now seeing which may be 6/9 or 6/12. Alternate an
occluder rapidly between the two eyes. Ask the patient each time
which is better? Then, fog the better seeing eye with +0.25 D and again
ask which is better? Continue this process, with + 0.25 D increments
until both eyes are equally fogged. At this point, the monocular
refractions of the two eyes are balanced and the accommodation is
equally suppressed.
Now, remove the monocular cover to allow the eyes to
see binocularly the line in question, and remove plus lenses
simultaneously from both eyes, in increments of +0.25, until he sees
the 6/6 line clearly with both eyes.
Though the description seems long, it will be found that if the
original refraction is perfect the difference between the two eyes will
not be more than +0.25 D.

9 Chapter 1: Accommodation
Full Accommodation Suppression
In this test +2.0 D lenses are used to fog the vision, instead of + 0.75
D, which reduces the vision instead to 6/60 or 6/36. The rest of the
procedure is same as the partial fogging method.
Though some patients will find it difficult to explain the difference
in vision with so extreme fogging but if the patient is able to feel the
difference in acuity with this test, then it means that the manifest
refraction is grossly faulty with undercorrection in plus or over-
correction in minus.
Prism—Dissociation Test
In this test, vision is fogged with +0.75 D, but the dissociation of
images in the two eyes is accomplished by vertical prisms, rather
than by alternate occlusion. The patient is asked to concentrate on
a single letter with both eyes open. Vertical prisms are introduced
before the two eyes, of usually 4PD to 6PD, which will maintain
vertical dissociation. Then fogging is done by introducing plus
lenses in increments of +0.25 D, to blur the clearer line until both are
equally blurred. At this point, prisms are removed and the extra plus
lenses also.
This test is supposed to be more sensitive and gives more
consistent results.
Causes of Unequal Amplitudes
In spite of best of efforts, if unequal amplitude persists, then reasons
for such situation should be looked for. Uniocular trauma, blunt or
penetrating, is a frequent cause of unequal amplitude. Early cataracts
and early presbyopia, long-standing anisometropia and incorrect
refraction are the other common causes.
SUBNORMAL ACCOMMODATION
Subnormal accommodation is a term used to denote accommodation
amplitude recordably less than for the patient’s age.
Presbyopia is a physiological insufficiency of accommodation
that comes naturally with advancing age. Hyperopia is another

Management of Refractive Errors and Prescription of Spectacles 10
condition, where the amplitude may be normal, but a premature
presbyopia sets in. Therefore, before labeling a person having a
truly subnormal accommodation power, cycloplegic refraction is
mandatory to rule out hyperopia or hyperopic astigmatism. The
following conditions should be kept in mind before labeling a true
subnormal accommodation as idiopathic.
• Previous illness, such as postviral or exanthematous encephalitis
• Present illness, like hypothyroidism, severe anemia, diabetes,
open angle glaucoma
• Drug intake, like anticholinergics, phenothiazines, tranquilizers,
chloroquine, etc.
Complete paralysis of accommodation is rare. But the above
mentioned causes can lead to complete accommodative paralysis
and can be caused by cycloplegic agents, midbrain disorders, Adie’s
syndrome, Panretinal photocoagulation, etc.
The most common causes for unilateral accommodation
paralysis are trauma, uveitis, and acute angle-closure glaucoma.
Accommodation insufficiency may be manifested as poor
amplitude or as poorly sustained accommodation or as accommo-
dation ‘inefficiency’. Poorly sustained accommodation most
frequently occurs in uncorrected hyperopes, where accommodation
cannot be maintained for long and either asthenopic symptoms
ensue or frequent blurring occurs in near work.
Accommodation inefficiency is a condition where a patient takes
time to focus at a near object after seeing at a distant object. This may
occur in some of the conditions where ciliary muscles are affected or
can be idiopathic.
REFRACTIVE ERRORS AND ACCOMMODATION
Let us see what relationship exists between refractive errors and
accommodation. An emmetrope differs from an optically corrected
ametrope, whose ametropia has been corrected with glasses or
contact lenses, because each of them have a different accommodation
demand on their ciliary-lens apparatus in performing near tasks.
Here are some examples to be remembered in doing presbyopic
corrections in different refractive errors:

11 Chapter 1: Accommodation
• A 8 D or 10 D myope, who wears a full spectacle correction for
distance will require less accommodation for near viewing than
if he is wearing contact lenses. This is why a 40-year-old patient
has difficulty in reading when he switches to contact lenses from
spectacles
• The 10 D hyperopic person requires more accommodation
for near targets with glasses, than when he switches to contact
lenses. The explanation of this phenomena is based on the optical
effectivity of various corrective lenses, which incorporates the
vertex distance effect, in viewing near objects.
Table 1.1 is a good guide for understanding the vertex distance
effect the various corrections have on accommodation required for
reading:
TABLE 1.1 Accommodation required
With spectacle
correction With contact lens
correctionDifference
10 D myope 3.0 4.51.5 D less
10 D hyperope 6.5 4.52 D more
with reading distance at 30 cm, and vertex distance 20 mm
It may be surprising, but this is a true physical phenomena
and the magnitude of the difference in power and magnification,
depends on how far from the nodal point of eye a lens is placed and
whether it is plus or minus.
For a perfect correction of refractive error, a lens would have to be
placed inside the eye, at the nodal point. An intraocular lens subverts
most of these problems; but since it is a pseudolens, the laws of
accommodation does not apply here.
Further, to the above explanation, spectacle or contact lens,
all correct the refractive error and are said to have equal optical
effectivity, but only if the object is located at infinity; the optical
effectivity changes for near objects as it will be imaged at a different
distance by each type of correction, and therefore, the demand for
accommodation will be different in each correction.

Management of Refractive Errors and Prescription of Spectacles 12
PEARLS
As has been seen, accommodation problems are common and
varied. Different ages and different refractive errors have different
demand on accommodation, and therefore, in the process of
correcting a refractive error, the role of accommodation must always
be kept in mind. The following pearls will guide through a smooth
and hassle-free journey of correcting accommodative problems:
• As mentioned in the introduction, an accurate history taking is
paramount. Correlate its relevance and compatibility with the
clinical findings.
• Use an accommodation measuring ruler, especially in presbyopic
correction, where most of surprises are lurking.
• Cyclopegia should be used judiciously.
• Do not rely on manifest refraction alone at any age, especially
when refracting a first timer patient. Always perform cycloplegic
refraction also.

Cycloplegia
2
INTRODUCTION
Cycloplegia, though thought by many clinicians, to be used only out
of necessity, is one of the vital ingredients for solving many clinical
problems. It is not a medicine to be put in a side-table drawer, and
used sparingly. Actually, it is one of the most required diagnostic
tools which must be used judiciously to enable us to learn more
about refractive conditions than is evident by manifest refraction
alone.
To be more emphatic, cycloplegia is mandatory in refracting
children and young adults even up to the age of 21 years! In my
practice, cycloplegic refraction is performed routinely each time
when a young patient comes for the first time and for yearly follow-
up visits. You will be surprised, how often a hyperopia or hyperopic
astigmatism is uncovered. Remember this pearl: Any patient who
complains of headache or other symptoms of ocular asthenopia,
irrespective of his vision, must undergo cycloplegic refraction. You
might be amazed to know that such patients have already gone
from pillar to post, visited all related specialties, but headaches
have persisted. And then, wisdom prevailed in some doctor, the
patient was referred and a good cycloplegic refraction exposed his

Management of Refractive Errors and Prescription of Spectacles 14
refractive error, mostly hyperopia and/or astigmatism. And a simple
spectacle correction alleviated all his problems. The more you
learn from cycloplegia, the more you benefit the patient and will be
overwhelmed to find that such a simple procedure produces such
satisfying results for the patients.
Let us now delve into the pharmacogenics of cycloplegia.
An ideal cycloplegic drug should possess the following charac-
teristics:
• Rapid onset of cycloplegia.
• Maximum relaxation of accommodation.
• Short duration of action.
• No residual side effects.
• No toxic effects—locally or systemically.
Till date, whatever drugs we have in our basket, none have the
entire above characteristics.
A cycloplegic drug is then chosen, depending on the age, the
degree of iris pigmentation, the type of refractive error discovered on
manifest refraction, local condition of eye, especially the angle depth,
and any neurogenic disorder, e.g. epilepsy. Further, the dosage and
concentration has also to be titrated according to the patient. It is
to be remembered that all cycloplegic drugs produce mydriasis also.
But a primarily mydriatic drug does not produce cycloplegia, e.g.
neosynephrine or eucatropine, very little cycloplegia.
A cycloplegic agent is used in the eye for following conditions:
• To aid in refraction.
• Paralyze iris and ciliary body postoperatively.
• Relieve ciliary spasm.
• Break iris synechiae.
• To treat anterior uveitis.
As an indispensible aid in refractions, it should be used in the
following conditions:
• In all children, up to 12 years of age, as a mandatory procedure.
• Manifest refraction not compatible with vision, up to 21 years of
age.
• Whenever refraction yields variable results, at any age.
• Symptoms relating to ocular asthenopia, irrespective of vision.
• Suspected extraocular muscle imbalance.

Chapter 2: Cycloplegia 15
• Whenever patient’s complaints are disproportionate to the
manifest refraction. A myope with frontal headaches—may be
overcorrected or headaches in moderate hyperope—may be
undercorrected.
• Early presbyopia, especially when glasses have never been worn.
• In infants and young children, where vision is difficult to assess.
• In bedridden or mentally challenged patients.
• In suspected or actual ciliary spasm.
• In gross anisometropia or antimetropia.
CONTRAINDICATIONS
In the following, cycloplegia should be avoided or used with caution:
• Without or absence of patient’s consent.
• History of drug reactions, like a previous episode in young child
with atropine.
• History of angle closure attacks.
• Critically narrow angles. Here, if necessary, a short-acting
cycloplegic can be used, with informed consent that angle
closure attack may be precipitated.
SOME SPECIAL SITUATIONS
• Occasionally you may face a situation, where you think that a
cycloplegic examination is a must, but the patient expresses
inability for a return visit. It is prudent not to fall prey to a
manifest refraction only and prescribe spectacles. The patients
may be politely advised to return according to his convenience
for a cycloplegic refraction and a postcycloplegic test. Or you
can suggest a cycloplegic refraction now and a postcycloplegic
final prescription, at his convenient clinic (provided the other
clinician is conversant with what you intend!). In cases, if you
find that the cycloplegic refraction does not differ much from the
manifest, and you can assure the patient that he need not take a
second visit any place, then a final prescription can be written.
• Another similar situation where the patient is unable to return for
a postcycloplegic check.

Management of Refractive Errors and Prescription of Spectacles 16
The following example will obviate your anxiety:
A young man visits clinic with complaints of headaches on
reading and expresses inability to return next day as he is leaving for
abroad next morning and insists on examination as this will bother
him in a foreign city. The manifest refraction yields +0.75 D OU and
Prince ruler, full amplitude.
This small amount of hyperopia should raise suspicion as to
probable more hyperopia which the patient is compensating by
excessive accommodation. Cycloplegic refraction yields OU +3.0 D
hyperopia! The fort has been conquered. But only half! What should
be done now as the person will not come for final prescription. Post-
cycloplegic test in these cases is important, as full correction may not
be tolerated and will cause blurring in distance. Here it will be wise
to give half correction, e.g. +1.5 D and for reading only, as this is what
is causing his main problem; and the patient may be explained about
his error. He will remain symptom free, till his next visit few years
later.
QUALITIES OF A CYCLOPLEGIC DRUG
Effectiveness
The purpose of cycloplegic refraction is to eliminate the variability
created by an unpredictable accommodation. The most effective
drug, therefore should completely suppress accommodation. But
unfortunately most drugs do not. Some residual accommodation is
still left behind. This residual accommodation depends upon again
the age of the patient, the degree of refractive error, the dosage and
the concentration of drug, the iris color, etc.
It is always wise to know the residual accommodation by a Prince
ruler, prior to performing cycloplegic refraction. In young patients,
below 30 years age, a residual amplitude of less than 2 D, can be
considered acceptable; between 30 years and 40 years +1.5 D and
above 40 years, no more than 1.0 D is acceptable. If the residual
accommodation is beyond the above limits, then the dosage is to be
increased or a stronger cycloplegic should be instilled.
Table 2.1 illustrates the drug of choice, dosage, concentration,
mechanism of action, duration, etc. for firsthand knowledge.

Chapter 2: Cycloplegia 17
Recommended Dosage (Table 2.1)
There is a considerable overlap in the choice of drug to be used in a
particular patient. There does еxistrule-of-the-thumb, but the type
of drug to be used depends upon the indications given above, upon
the presenting condition and clinical experience of the physician.
Broadly speaking, atropine is the drug of choice in an infant and
toddler; but here again the concentration varies and the type of
delivery. Atropine ointment is preferred below age 1 year, as its
systemic absorption in slow. Drops can be instilled between 1 year
and 3 years. Homatropine 2% is preferred between 3 years and
5 years age. But in a child of 8 years with strabismus, atropine will be
preferred whereas under other conditions cyclopentolate 1% or 2%
is instilled between 5 years and 12 years. Over 12 years, tropicamide
1–2% suffices in most instances.
As a rule, lesser cycloplegic agent is preferred for children with
normal vision and stronger for children with reduced vision or
muscle imbalance.
Though only specified concentration and dosage should be used,
taking into account the age and suitability of patient, but many times
the desired effect is not produced (This is very easily determined
as the patient’s near vision still remains clear.) In such situations,
there is a tendency by the clinician to instill some more drops. This
practice is to be discouraged, as more instillations may exceed the
safe dosage and liable to induce toxic effects. The patient may be
called another time and a stronger cycloplegic agent used.
Duration of Action
Each cycloplegic agent has a different duration of action. Though
most of the cycloplegic agents have a known duration of effect but
there have been reported cases of effect of cyclopentolate 1% lasting
over 4 weeks. Patients should be warned of such untoward action of
drugs, especially for stronger agents like atropine and homatropine.
If the patient feels alarmed or anxiety overrides his common sense,
then the patient may be called and a drоpof 1% pilocarpine instilled.
This may help in cases where tropicamide or cyclopentolate is used
but will not be effective for atropine or homatropine. The effect of
pilocarpine may wane off before the effect of cycloplegia, and the

Management of Refractive Errors and Prescription of Spectacles 18
TABLE 2.1
Characteristics and dosages of cycloplegic agents
Cycloplegic drug
Pharmacologic action
Concentration
Age range
Dosage
Maximum cycloplegic effect
Duration of mydriasis
Duration of cycloplegia
Atropine sulfate ointment
Parasympatholytic
0.5 and 1%
Below 1 year
TDS for 3 days
1–3 days
10–12 days
15 days
Atropine sulfate solution
Para sympatholytic
0.5–1.0%
1 to 3 years
1 drоpTDS for 3 days
1–2 days
10–12 days
15 days
Homatropine hydrobromide solution
Parasympatholytic
2%
3–21 years
2 drops 10 minutes apart
60 minutes
24–36 hours
24–36 hours
Scopolamine (solution or ointment)
Parasympatholytic
0.25%
3–10 years
2 drops 10 minutes apart
60 minutes
2–3 days
3–5 days
Cyclopentolate solution
Parasympatholytic
0.5%, 1%

and 2%
Above 25 years 3–21 years
2 drops No repeat
45 minutes
16–24 hours
16–24 hours
Tropicamide solution
Parasympatholytic
1% 2%
21 years above 12 years above
2 drops 5 minutes apart
30–45 minutes
6–12 hours
6–12 hours

Chapter 2: Cycloplegia 19
blurriness might return. Sometimes, only mydriasis may wear off but
cycloplegia may persist. At best, it is always prudent to explain to the
patient the consequences of the effect of such drugs and alleviate his
fears. A good idea is to have patient wear dark goggles when going
outdoors as this may give some respite from glare and permit at least
some activity outdoors.
Side Effects
As we know all cycloplegics produce mydriasis also. Thus, photo-
phobia and glare are normal side effects. This has to be notified to
the patient before a cycloplegic is instilled and also the duration of
action of each drug. This discomfort can be minimized by advising
the patients to wear dark goggles in daylight, till the effects wanes.
Serious side effects are not common and for the most part, are
dose-related. In any case, the dosage and concentration must never
be exceeded. Before instillation of a cycloplegic, the age, iris color,
presumed type of error, history of any previous untoward action must
be taken into consideration. If the cycloplegic effect has not occurred
with a particular agent, another drug should be tried later or some
more time given to have the full effect, rather than instilling more
drops. Atropine is known to cause maximum side effects. In children,
even normal doses can cause serious side effects. Idiosyncrasy to
atropine can cause alarming side effects and toxicity, but commonly
they result from excessive systemic absorption. Marked flushing of
face, dryness of mouth, hot dry skin, fever, restlessness, rapid pulse,
can all occur. The following hard fact will surprise the reader. A
1% atropine sulfate solution contains 10 mg of atropine per mL ; there
are about 10 drops in one mL (milliliter). The instillation of one drоpin each conjunctival sac will yield a dosage of 2 mg (1.0 mg each)
of atropine. This is about four times the usual adult parenteral dose!
Extreme toxicity can occur in idiosyncrasy or in hypersensitive
individuals, such as Down’s syndrome, and can result in halluci-
nations, convulsions, delirium, coma and even death. Locally
atropine can cause induration and dermatitis over lids and cheeks
and conjunctival congestion. Homatropine and cyclopentolate
are relatively safer but in young children, care should be observed
regarding dosage and fair skin. Cyclopentolate 1% is known to cause

Management of Refractive Errors and Prescription of Spectacles 20
restlessness, disorientation and delirium. These central nervous
system side effects are pronounced in very young children, especially
with history of epilepsy or related disorders. All water-soluble
cycloplegic drugs are absorbed through conjunctiva, lacrimal and
nasal mucosa. An aqueous preparation placed in conjunctival sac,
will appear in the nose within one minute.
In order to decrease the systemic side-effects, atropine can be
used as an ointment which lessens the systemic absorption. In case
of drops, the medial canthus can be kept pressed for a minute or two,
to prevent the drug entering the lacrimal sac and nasal mucosa.
Treatment
Local skin and conjunctival reactions are best treated by
discontinuing the drug. Fever and flushing can be managed by cold
sponging and antipyretics.
Serious side effects or toxicity may require hospitalization
particularly in children.
CYCLOPLEGIA AND GLAUCOMA
It cannot be overemphasized that strong cycloplegics are not to
be used in a patient with possibility of angle closure. Whenever
it becomes a necessity to use cycloplegics, as a general rule, the
following ground rules should be followed:
• Make an informed consent regarding the reasons and added risk
of using cycloplegia. Also, the patient may be kept in the clinic for
some hours, to immediately institute corrective measures
• Use a mild agent like cyclopentolate 0.5% or tropicamide 0.5%
• If a miotic has been used to counter the mydriasis, then keep
the patient in clinic, till mydriatic effect has subsided. This is to
ensure that miosis itself may not trigger an angle closure attack, a
significant clinical point to be kept in mind in refractions done in
patients suffering from glaucoma.
In case where patients with narrow angles are kept on miotic
therapy as a preventive measure from angle closure attack, the
refraction will vary significantly if a mild cycloplegia is used in
their case; miotics increase the tone of ciliary muscles and thus

Chapter 2: Cycloplegia 21
accommodation. Such patients may shоwvariable refractions during
miosis and after cycloplegia. If the patient is to be kept for long on
miotic therapy (where laser peripheral iridotomy is not done), then
it is advisable to have the refraction done under miotic conditions.
Open angle glaucoma itself is known to causes changes in
refraction. This change is compounded, when glaucoma therapy
changes with time. But since cycloplegic agents are safe in this type
of glaucoma, it is prudent to use a cycloplegic for refraction.
CLINICAL PEARLS
A pertinent question always haunts the clinician, as what pre-
scription to be given after a cycloplegic refraction. Have the patients
to be always called for a postcycloplegic examination?
The answer is as elusive as the question. Following are the cases
where postcycloplegic test in indicated:
Children
Children under 18 or 21 years, who shоwhyperopia but are
asymptomatic will not require any glasses and need not come for a
second visit.
Myopes will have the same error after cycloplegic refraction and
will not shоwany discrepancy in a postcycloplegic test and therefore,
do not need another visit. But children showing astigmatism,
anisometropia or demonstrating symptoms, need a postcycloplegic
exam. Children with mixed astigmatism require special attention
during a postcycloplegic test.
Adults
These are a major group manifesting ocular asthenopic symptoms.
Here manifest refraction may not yield any refraction error or may
yield variable error. Cycloplegic refraction now yields hyperopia
or astigmatism. Such patients require a postcycloplegic test for
acceptance. Patients whose manifest and cycloplegic refraction
yield compatible data, prescription can be safely given and post-
cycloplegic test is not needed.

Management of Refractive Errors and Prescription of Spectacles 22
There is another group in the presbyopic or prepresbyopic age. If
the manifest and cycloplegic refraction are same, then prescription
is promptly given. But where a significant difference appears in the
two refractions, a postcycloplegic test is warranted. Cycloplegic
refraction after 50 years of age is rarely needed.
SUMMARY
• Cycloplegia must be used judiciously and kept as an essential
tool in the arena of examination.
• The type of cycloplegic should be not indiscriminately chosen
and indiscriminately used. Selection should be done depending
upon the age of patient, type of error, symptoms of patient, iris
color, any systemic anomaly, local anomaly in eye, etc.
• Patients should be informed (consent taken verbally may suffise)
regarding the effect of cycloplegia and its side effects.
• Postcycloplegic test should be taken seriously, as you may find a
great difference in the cycloplegic refraction and what the patient
accepts.
• Never, in any circumstances, refract a child below 12 years
without cycloplegia. And a young person, who has symptoms of
ocular asthenopia.

Hyperopia
3
INTRODUCTION
Hyperopia or hypermetropia as is usually called, though not as
common as myopia, but still is a perplexing disorder of the eye and
is sometimes difficult to deal with. In myopia or astigmatism, the
patient comes to you with a clear cut, specific complaints of blurred
vision. In hyperopia, on the contrary, the patient’s vision is normal
but comes with complaints which may be vague at times, and can
be overlooked frequently. This is exactly what is happening in a busy
outpatients department. If you start refracting these patients with
cycloplegia, you will be amazed at the number of patients you were
missing. Then there is another pitfall. After successfully finding a
hyperopia, you are in a dilemma as to what and how the plus lens
prescription should be given. You may plunge into depression,
that after all your labor, the patients comes running back that his
vision has now become blurred with the prescription and he is not
comfortable. Thus, hyperopia is not as simple as it appears and you
shall learn to tread carefully as you go through this chapter.
Ch-3.indd 23 06-04-2015 15:08:22

Management of Refractive Errors and Prescription of Spectacles 24
DEFINITION
In hyperopia, the optical power of the unaccommodating eye is weak
to form a clear image of a distant object on the retina. But this is easily
compensated, in most cases, by using the power of accommodation.
In all cases, this may not be possible and if so, at the expense of
so much of an accommodative effort, the patient starts manifesting a
basketful of symptoms.
In a recap, let us go through some basic features of hyperopia.
Some terms used in hyperopia, like total, latent, manifest, absolute
and facultative need to be clarified, as they will be used frequently in
this chapter. It will be simpler if an example is used.
Suppose a male patient comes to the clinic, with complaints of
fatigue and headaches. His vision is 6/9 and refractive error of OU
+4.0 D. Seeing this, a cycloplegic refraction is done, which reveals
+6.0 D of error. The patient is called back for a postcycloplegic test.
Now, putting +1.0 D, each eye, in the trial frame improved is vision to
6/6.
To explain, the total error found with cycloplegia is +6.0 D and
this is the ‘total’ hyperopia. His plain refraction had showed only +4.0
D. This was the ‘manifest’ refraction and the remaining (+2.0) which
revealed only after cycloplegia, is ‘latent’ hyperopia. From +4.0 D of
manifest hyperopia, he is correcting most of it by his accommodation
and needs only +1.0 D addition for further clarity of vision. Thus +1.0
D is the amount he needs as an outside help and is called ‘obsolute’
(which cannot be overcome by accommodation) and remaining +3.0
D is the ‘facultative’, which the patient is compensating by his faculty
of accommodation.
ETIOPATHOGENESIS
A short note on this is mandatory to understand and more
importantly, to make the patient understand. Hyperopia, basically,
as we all know, is due to the defect in the manufacturing of our
eyes—short, small eyes, with sometimes flater corneas. And as this is
since the beginning, it becomes difficult for the patient to make him
accept his problem.
Ch-3.indd 24 06-04-2015 15:08:23

Chapter 3: Hyperopia 25
As age advances, the lens grows in size, the accommodation in
a high hyperope causes the lens to further increase its curvature
(though in some part it is compensated by the stiffness of lens)
and all these mechanisms added together felicitate an attack of
angle closure glaucoma. The clinical pearl here is to motivate the
patient to use specks constantly which will obviate the need for extra
accommodation. Having said that, let us examine when glasses are
necessary, how to personalize them, should they be worn fulltime or
only for near. When closely observed, one denominator stands out
and that is ‘age’. Age is the single largest factor which influences the
management of hyperopia. For convenience of management, let’s
divide age into:
• Up to 5 years
• 6–21 years
• 21–40 years
• Above 40 years.
CHILDREN
Children are born hyperopes. We know that at birth the average
size of an eye is about 17.0 mm. It rapidly attains 20.0 mm by end
of one year, and by 3 years, it has attained around 23.0 mm. Then
very gradually it further grows by 0.5–075 mm by 12 years of age.
The corresponding large hyperopia is easily overcome by more than
adequate accommodation. It is only when something becomes
wrong in this development, that hyperopia results.
So, in what circumstances, will a child come to the doctor! And these
are:
• Diminished vision, in one eye or both, noted accidentally in
routine examination at school or elsewhere
• Strabismus
• Unexplained red eyes or watering
• Nystagmus, or any other sign noted by parent or teacher.
Headaches, a prominent symptom in adults, are uncommon
in children. Since each of above categories have different set of
management, let us study each of them.
Ch-3.indd 25 06-04-2015 15:08:23

Management of Refractive Errors and Prescription of Spectacles 26
• Whenever diminished vision is reported in a child below
5 years and a cycloplegic refraction shows high hyperopia (+5.0
or more), then appropriate specks, according to the subjective
correction which improves vision, is given. Early correction
not only accelerates normal visual acuity development but also
normal development of the eyes.
Where there is anisometropia and unilateral amblyopia, then
in addition to specks, amblyopia therapy has to be initiated.
In children with high hyperopia but ‘normal uncorrected
vision’, need not be interfered with but they should be advised for
regular checkups.
A third group is with high hyperopia, normal vision but
complaining of symptoms like restlessness, fatigue or red eyes.
These children again require cycloplegic refraction and then best
subjective correction.
It is amazing how quickly and comfortably children adapt
to high numbers, so much so that, a child may demand for his
specks on awakening in the morning.
• Child with esotropia: An esotropic child requires a full
cycloplegic refraction with atropine. It is important to know the
total hyperopia. Having determined this, the full cycloplegic
correction is mandatory. Sometimes, after giving the full
cycloplegic correction, there might still remain a small amount
of esodeviation. This is not necessarily a nonaccommodative
component of esotropia. Such children are refracted again
between 1 month and 3 months and you may be surprised to
find that some amount of hyperopia is still remaining. New
prescription is given and now all extra accommodative effort has
been eliminated, the child may become orthotropic.
There is a general tendency to correct little less of hyperopia,
especially if hyperopia is around +8.0 or +10.0. This school of
thought probably generated because of sympathy towards child
or out of fear that the child will not tolerate such high numbers.
It is reiterated that a child’s adaptability is amazing and it is
surprising how well a child tolerates such high numbers. By
correcting, say half of hyperopia, you are not benefitting the
patient. Neither his vision will improve nor his deviation.
Ch-3.indd 26 06-04-2015 15:08:23

Chapter 3: Hyperopia 27
• The hyperopic anisometrope child: These are slightly difficult
cases to deal with.
There are two examples to explain:
1. A child of 5 years has the following findings:
Without correction With correction (after cycloplegic Ref.)
OD 6/9 +2.5 6/6p
OS 6/18 +4.5 6/9p
There are two options:
  i. First, since the vision is improving in both eyes, to give a full
prescription.
ii. Second, since there is hardly any difference with correction
in OD, it can be left alone and only the difference in
refraction of the two eyes can be given in OS. This
concept stems from the rule that both eyes accommodate
equally. To see clearly OD accommodates by +2.5 D and
simultaneously OS also accommodates by + 2.5 D.
The rest +2.0 D remaining in OS to view 6/9 line, is
compensated by specks. As a general rule, I follow the
second rule in practice.
2. A child of 5 years, has the following findings:
Without correction With correction (after cycloplegic Ref.)
OD 6/9 +2.5 6/6p
OS 6/36 +6.0 6/24