Myopia, or nearsightedness, is a refractive error where light rays focus in front of the retina when the eye is at rest. It can be classified as simple myopia, pathological myopia, or acquired myopia. Simple myopia is usually not associated with eye disease and typically does not exceed -6 to -8 diopters. Pathological myopia is a rapidly progressive form that can lead to high myopia over -10D and degenerative changes in the retina and choroid. Treatment includes optical correction with glasses or contacts, and refractive surgery such as LASIK for higher degrees of myopia. Prognosis is generally good for simple myopia but guarded for pathological myopia due to risk of vision

1. MYOPIA

2. SOURCES
2
• Theory and practice of optics and refraction by AK
Khurana
• Borish’s clinical refraction
• Strabismus simplified,Pradeep Sharma
• Parsons’ Diseases of the Eye - 22nd Edition, 2015

3. OUTLINE
• Optics of myopia
• Classification
• Treatment of myopia
• Complications
• Prognosis

4. MYOPIA
• Derived from two Greek root words
(Greek: μυωπία, muōpia, from myein "to shut" - ops (gen. opos)
"eye“)
• Myopia or shortsightedness is a type of refractive error in
which parallel rays of light coming from infinity are focused in
front of retina when the accommodation is at rest

5. Image formation
• In myopia image formed in front of retina
5

6. Optics of myopia
• The optical system is too powerful for its axial length
• Image of distant object on retina is made up of circle of
diffusion formed by divergent beam since the parallel rays of
light coming from the infinity are focused in front of the
retina
• Far point is finite point in front of eye
6

7. Optics of myopia
• Nodal point is further away from retina
• Accommodation in uncorrected myopes is not developed
normally, they may suffer from convergence insufficiency,
exophoria,and early presbyopia

8. TYPES OF MYOPIA
8
• Etiologically
• Axial myopia :result from increase in anterioposterior
length of eyeball
• Curvatural myopia :occurs due to increased curvature of
cornea or lens or both
• Index myopia :increase in refractive index of crystalline
lens associated with nuclear sclerosis
• Myopia due to excessive accommodation :occurs in
patients with spasm of accommodation
• Positional myopia

9. TYPES OF MYOPIA
• Clinically,
• congenital myopia
• simple or developmental myopia
• pathological or degenerative myopia
• acquired myopia
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10. TYPES OF MYOPIA
 According to degree:
Classically:
Very low : upto – 1.00D
Low : –(1.00-3.00)D
Medium : –(3.00-6.00)D
High : –(6.00-10.00)D
Very high : above –10.00D

11. Congenital myopia
• Seen more frequently in children who were born prematurely
or with various birth defects
• Usually error is about 8-10D, which mostly remains constant
• Most of the times the error manifests as anisometropia
• May sometimes be associated with other congenital
anomalies such as cataract, microphthalmos, aniridia,
megalocornea
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12. Congenital myopia
• Early correction is desirable to help the children to develop
normal distance vision
• Full cycloplegic refractive error including any astigmatic
correction should be prescribed
12

13. Simple myopia
• Also known as physiological or school myopia
• Physiological error not associated with any disease of eye
• Etiology:
result from normal biological variation in the
development of eye
14

14. Simple myopia Aetiology
Axial Physiological variation in the
length of the eyeball
Curvatural Underdevelopment of eyeball.
-------- Role of diet in early childhood.
-------- Theory of excessive near
work.
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15. Simple myopia
Symptoms:
. Poor vision for distance
• Asthenopic symptoms
• eye strain due to
dissociation between
convergence and
accommodation
• May develop convergence
weakness and exophoria
and supression in one eye.
• Change in psychological
outlook
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16. Degree of myopia Visual acuity
-0.50 6/9-6/12
-1.00 6/18
-1.50 6/24
-2.00 6/36
-3.00 6/60
-4.00 4/60
-5.00 3/60
-6.00 2/60
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Degree of myopia Rough estimate of visual acuity

17. Simple myopia: SIGNS
• Eyes are large and prominent
• Slight deep anterior chamber
• Fundus is normal;rarely temporal myopic crescents may be
seen
• Usually error does not exceed 6-8D
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18. Simple myopia :diagnosis
• Confirmed by performing retinoscopy
19

19. Pathological myopia
• Rapidly progressive error resulting in high myopia usually
apparent during 1st decade of life
• Etiology:
1)Heredity
2)General growth process
20

20. Pathological myopia
• High myopia is considered to be sex linked recessive inherited
disorder
• It is said that increased axial length, degenerative changes in
retina and vitreous, and pathological complications are
determined by different genes.
• Inheritance can be AD, AR ,X-LINKED
21

21. 22
Genetic factors General growth
(play major role)
↓
More growth of retina
↓
Stretching of sclera
↓
Increased axial length
↓
Degeneration of choroid
↓
Degeneration of retina
↓
Degeneration of vitreous
Features of
pathological
myopia
etiological hypothesis for pathological myopia
(Plays minor role)
Elongation of the eyeball
posterior to equator in
pathological myopia.

22. Pathological myopia
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• Symptoms
• defective vision
• muscae volitantes
• night blindness

23. Pathological myopia
• Signs:
• Eyes are prominent, appearing elongated, and even
stimulating an exophthalmos
• Cornea is large and anterior chamber is deep
• Pupils are larger
• Refractive error:
increase by as much as 4D yearly
stabilizes at about the age of 20
but occasionally may progress until mid 30s
frequently result in myopia of 10-20D
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24. 25
Retinal changes in pathological myopia
Optic disc:
• appears large and pale
• at temporal edge a characteristic myopic crescent present
Degenerative changes:
• in retina and choroid are common.
• occurs tigroid appearance of fundus due to diffuse
attenuation of the RPE with visibility of large choroidal
vessels

26. Retinal changes in pathological myopia
• Foster- Fuchs spot may be present at macula
• Cystoid degeneration may be seen at the periphery
• In advanced cases there occurs Focal chorio-retinal
atrophy which is characterized by visibility of the larger
choroidal vessels and eventually the sclera, total retinal
atrophy, particularly at central area
27

27. Retinal changes in pathological myopia
• There may be associated lattice degeneration and or snail
track lesions
• Retinal tears, haemorrhage , retinal detachment may be
seen
• A posterior staphyloma due to ectasia or bulging of sclera
at posterior pole due to focal expansion and thinning .

28. Retinal changes in pathological myopia
• It occurs in about a third of eyes with pathological myopia,
and is virtually always peripapillary or involves the
macula.Staphyloma development can be associated with
macular hole formation
• Degenerative changes of vitreous include:
liquefaction, vitreous opacities, PVD
• Visual field shows contraction and sometimes ring scotoma
may be seen.
29

29. 30
Fundus changes in myopia
Foster-Fuch’s spot
Peripapilary and
macular
degeneration

30. 31
Choroidal neovascularization
associated with
a lacquer crack and high
myopia.
Peripheral retinal degernerations :
A:Lattice degeneration,
B:Snail track degeneration
C:Acquired retinoschisis
D:white-with-pressure
E:Focal pigment clumps
F:Diffuse chorioretinal degeneration
G:Peripheral cystoid degeneration

31. 32
Pathological myopia :complications
• Rhegmatogenous retinal detachment (RD)
• Foveal retinoschisis and macular retinal detachment without
macular hole formation may occur in highly myopic eyes with
posterior staphyloma, probably as a result of vitreous traction

32. Pathological myopia :complications
• Complicated cataract which may be either posterior
subcapsular or early onset nuclear sclerotic
• Nuclear sclerosis
• Vitreous haemorrhage
• Choroidal haemorrhage and thrombosis

33. 34
High myopia can be seen in these syndromes
• Down syndrome
• Stickler syndrome
• Marfan’s syndrome
• Prematurity
• Noonan syndrome
• Ehlers–Danlos syndrome
• Pierre–Robin syndrome

34. 35
Acquired myopia
• Causes:
• Index myopia : nuclear sclerosis
incipient cataract
. Curvatural myopia
increase of corneal curvature in diseased conditions like
corneal ectasias, and conical cornea
• Positional myopia

35. 36
Acquired myopia
• consecutive myopia
surgical overcorrection of hypermetropia
pseudophakia with overcorrecting IOL.
• Pseudomyopia
• Space myopia –Experienced when the individual has no
stimulation for distance fixation
It is never more than 0.75-1.5D

36. Acquired myopia
• Night myopia or twilight myopia
37
The emmetropic eye ,if accomodated for the middle range of
visusal spectrum,will be slightrly myopic for the shorter
wavelengths.
Increased sensitivity to shorter wavelength of light
Shift from photopic to scotopic vision at twilight

37. 38
Acquired myopia
• Drug induced myopia
-Cholinergic
-Steroid induced
-Sulphonamides

38. TREATMENT OF MYOPIA
39
• Optical treatment
• Surgical treatment
• General measures
• Visual hygiene
• Low-vision aids

39. Optical treatment
40
Guidelines for correcting low degree of myopia upto -6D
Children younger than 8yr should be fully corrected and
instructed to use their glasses constantly
Adult younger than 30 yrs:
usually accept their full correction.
Older than 30 yrs:
not able to tolerate a full correction over 3D if they have
never worn glasses before.
prescribe less than full correction with which the patient
has comfortable.

40. Optical treatment
41
Include prescription of appropriate concave lens
minimum acceptance providing maximum vision should be
prescribed.
never overcorrect myopia

41. Optical treatment
42
 guidelines for correcting high myopia
• full correction can rarely be tolerated
• under correct as little is compatible with comfort for
binocular near vision
• under correction to the tune of 1-3D or even more may be
required
• under correction is always better to avoid the problem of
near vision and minification of image.

42. 43
Modes of prescribing concave lenses
 Spectacles
 Contact lenses

43. Surgical treatment:
44
– Radial keratotomy
• Making deep (90 percent thickness radial incision in the
peripheral cornea leaving about 4mm central optical
zone.
• On healing flattens central cornea there by reducing
refractive power|(refractive error between -1.5to -6D.

44. Photorefractive keratectomy
Photorefractive keratectomy
• Photoablation of excimer LASER
– Which can accurately ablate corneal tissue to an exact
depth with minimal distortion of normal tissues
– Myopia is treated by ablating the central anterior corneal
surface so that it becomes flatter
– Approximately 10 micron of ablation corrects 1D of
myopia.

45. 46
• LASIK
• Laser in situ keratomileusis
• Currently most frequent performed refractive procedure
• Can correct myopia upto -10D
• Automated microkeratome is used to raise corneal flap
• Excimer laser applied to stromal bed and flap again
repositioned

46. General measures:
47
– Balanced diet rich in vitamins and proteins
– Early management of associated debilitating diseases

47. Visual hygiene:
48
– to avoid asthenopic symptoms
– adequate illumination during close work
– clarity of print should be good to avoid undue
ocular fatigue

48. Low vision aids:
49
– Indicated in patients of progressive myopia with
advanced degenerative changes where useful
vision cannot be obtained with spectacles and
contact lenses

49. Prophylaxis
50
• genetic counseling for people having
pathological myopia, not to marry
pathological myopic peoples

50. PROGNOSIS
51
Simple myopia
– Prognosis is good.
– Error usually does not progress beyond 6-8D
– Stabilizes by the age of 21
Pathological myopia:
– Visual prognosis is always guarded
– Possibility of progressive visual loss due to
degenerative changes and danger of complications
such as retinal detachment should be borne in mind.

51. THANK YOU