This document discusses refractive errors and myopia. It begins by defining refractive media and refraction. It then discusses the different types of refractive errors including myopia. For myopia, it discusses the etiology, classification, clinical presentation, complications and management. It notes that the main causes of myopia are excessive axial elongation of the eye or increased curvature of the cornea or lens. The main types of myopia are axial myopia, refractive myopia, and curvature or index myopia. Management options for myopia include glasses, contact lenses, and refractive surgery procedures.

2. ‫مف‬ْ ‫ف‬ ‫ه‬ُ‫ْم‬ ‫ک‬َ‫ُه‬ ‫ر‬َ‫ُه‬ ‫ت‬َ‫ُه‬‫و‬َ‫ُه‬ ‫همف‬ِ‫ م‬ ‫ر‬ِ‫ م‬ ‫نرو‬ُ‫ْم‬‫ب‬ِ‫ م‬ ‫بف الف‬َ‫ُه‬ ‫ه‬َ‫ُه‬ ‫ذ‬َ‫ُه‬
‫ون‬ُ‫ْم‬ ‫صر‬ِ‫ م‬ ‫ب‬ْ ‫ف‬‫ی‬ُ‫ْم‬‫ل‬َ‫ُه‬ ‫تف‬ِ‫ م‬ ‫م‬َ‫ُه‬ ‫ل‬ُ‫ْم‬‫ظ‬ُ‫ْم‬ ‫ف یف‬ِ‫ م‬۱۷

3. Refractive errors
Myopia

4. Refractive errors
Myopia
• Refractive media
• Refraction
• Types of refractive errors
• myopia.
• Types of myopia
• Management of Myopia.

5. REFRACTIVE MEDIA ‫ف‬
1. Cornea
2. Aqueous humours
3. Lens
4. Vitreous

6. EMMETROPIC EYE ‫ف‬
Normal eye

7. • Light moves in the air at speed
( 300,000 km/sec)

8. • The refractive power of any lens
is expressed by diopter (D)
• Total refractive power of eye is
59 D ≈ ‫ف 06ف‬D ‫ف‬(Total refractive power of the eye )
Light rays
17 ‫ف‬D
43 ‫ف‬D

9. REFRACTION ERROR ‫ف‬
 Emmetropia
 Ammetropia

10. Myopia ‫ف‬
(Short sighted(
Astigmatism
Hyperopia ‫ف‬
(Long sighted(
PresbyopiPresbyopi
aa

11. Accommodation
Prebyopia

12. Myopia
MYOPIA
NARAMAL
MYOPIA
short sightedness

13. Epidemiology
09/12/2014 13

14. Etiology of myopia
1. Axial myopia increase length
of eye ball
2. Curvature myopia increase
curvature of cornea
3. Index myopia
4. Positional and Lenticular
changing myopia
5. Myopia due to excessive
accommodation.

15. excessive ‫ف‬
accommodation
Curvature myopia ‫ف‬
Index myopia
Axial myopia ‫ف‬
Positional and ‫ف‬
Lenticular changing ‫ف‬
Lenticular changing ‫ف‬

16. Classification of
myopia

17. Clinical types of ‫ف‬myopia
1. Congenital myopia.(developmental
myopia)
2. Simple myopia. (5-6 diop) common.
3. Pathological or degenerative
myopia.(20 diop)
4. Acquired myopia

18. 1.1. Axial myopiaAxial myopia: (more common)
increase in the eye's axial length
( it’s too long for its optical power)
2.2. Refractive myopia (accomedationalRefractive myopia (accomedational :
excessive refractive power
(eye is optically too powerful for its axial length)
• Curvature myopia: excessive curvature of
cornea or lens
2. Index myopia: index of refractive media.

19. 1. Congenital myopia, also known as
infantile myopia, is present at birth .
Myopia 10 D ,Increase slowly each
year
2. Young onset myopia (pathological )
occurs prior to age 20 worse myopia
3. School myopia appears during
childhood, particularly the school-age
(5-7 years)
4. Early adult: onset myopia occurs
between ages 20 and 40

20. Acquired myopia ‫ف ف‬
1. KERATOCONUS

21. Acquired myopia ‫ف ف‬
2. Cataract
3. Diabetes

22. Acquired myopia ‫ف ف‬
4. Marfan syndrome
(Spherophakia )
5. Posterior Staphylom

23. Clinical picture ‫ف‬
Distance Poor vision .
Half shutting of the eyes.
Prominent of eyeball.
AC is deep than normal.
Pupil are large.
 Pupil sluggish reactive.
E.

24. Clinical picture
Frequent squinting
of eyes
Eye strain or headaches
from trying to focus
Amblyopia.
Close reading

25. Morphologic changes
(sign)
Progressive myopia :
deep anterior chamber
atrophy of ciliary muscle
The volume of vitreous
small (vitreousopacifications)
detachment floaters.

26. fundus change :
(sign)
 Retinal degeneration .
large disc and white
crescent-shaped.
posterior staphyloma
Rretinal detachment

27. Complication ‫ف‬
• Retinal detachment.
• Complicated cataract.
• Choroidal hemorrhage and detachment.
• Choreoretinal degeneration
• Vitreous hemorrhage and degeneration.
• chronic simple glaucoma
Progonsis
In simple myopia good
In Pathological not good
‫ی‬ ‫ونک‬ ‫واده‬ ‫کی‬ ‫مین‬ ‫خپل‬ ‫په‬ ‫باید‬ ‫مایوپیا‬ ‫درجه‬ ‫ه‬ ‫لو‬ ‫دوه‬‫ړ‬ ‫ځ‬ ‫ړ‬ .

28. How are Myopia
corrected?
1.Non surgical options :
 Spectacles (mines glasses)
 Contact lenses on cornea.

29. Pinhole glasses Autorefractor
View through an autorefractorPhoropter

30. 2.Surgical intervention :
A.Intraocular surgery : clear lens
extraction (with or without
IOL), A.C IOL
B.Laser treatment on
cornea :
• Radial keratektomy
• Excimer laser
• Epikeratophakia
• Keratomaleusis

31. • First used in U.S in 1978
• Treats low to mod.
• RK reduces myopia
flattens the cornea
centrally.
• The surgeon makes
deep radial incisions
Radial Keratotomy

32. Laser Sub-Epithelial
Keratomileusis
• LASEK can treat mild to moderate
myopia.
• The epithelial flap is repositioned
afterward.
• LASIK is now the most commonly
performed refractive surgery in the
world

33. LASIK

34. ‫تنی؟‬ ‫پو‬‫ښ‬‫تنی؟‬ ‫پو‬‫ښ‬
‫مننه‬ ‫عالم‬ ‫یو‬ ‫مو‬ ‫توجه‬ ‫!له‬

35. ‫ب‬ْْ ‫للبا‬ٌ‫لا‬ ‫ل‬ِ‫ٌل‬‫ا‬ُ‫ل‬‫یا‬ ‫فعتبرو‬

36. The etiological hypothesis for pathological
myopia
Genetic factors General growth process
(play major role) (plays minor role)
↓
More growth of retina
↓
Stretching of sclera
↓ ↓
Increased axial length
↓
Degeneration of choroid Features of
↓ pathological
Degeneration of retina myopia
↓
Degeneration of vitreous

38. ASTIGMATISM
• Definition
• Types of astigmatism
• Simple astigmatism
• Compound astigmatism
• Mixed astigmatism
Types of astigmatisim
Regular
• ١: simple
• ٢. Compound
• ٣: Mixed

39. 39
Astigmatism

41. REGULAR ASTIGMATISM
• According to the rule
• not According to rule
• Treatment
• prognosis

43. ETIOLOGY
• Change curvature of cornea and
lens.
• Change in refractive index of
lens.
DIAGNOSIS
• Retinoscopy
• Keratometry
TREATMENT

44. APHAKIA
1. Congenital absence of lens.
2. Surgical aphakia.
3. Absorption of lens matter.
4. Traumatic extrusion.
5. Posterior dislocation.

45. Clinical pictures
• Vision
• AC is deep
• Iridodonesis
• Limbal scar
• Retinoscopy

46. TREATMENT
1. Spectacles
2. Contact lens
3. IOL
4. Refractive surgery

47. ANISOMETROPIA
Types
1.Congenetal
• (myeopic or hyerop)+ Emmetropic
• mild Ammetropic+Ammetropic
• high Ammetropic+Ammetropic

48. ‫لیدنه‬ ‫زو‬‫ړ‬PRESBYOPIA
Presbyopia is a condition of
physiological
insufficiency of accommodation
leading to a progressive fall in
near vision.

49. treatment
 Near vision addition
 Convex lens
 40 years- 1.0 D
 45 years- 1.5 D
 50 years- 2.0 D
 55 years- 2.5 D
 60 years- 3.0 D
 Better to undercorrect than
overcorrect

50. Spectacles:
• Monofocals
• Bifocals
• Trifocals
• Progressive lenses

52. ‫تنی؟‬ ‫پو‬‫ښ‬

53. Helmholtz Accommodation

55. SCHACHAR’S theory
•Presbyopia is due to
growth in equatorial
diameter, leads to
decrease in
perilenticular space.
•Contraction of ciliary
muscle cannot tense
zonules and expand
lens coronally.
•SCHACHAR introduced
use of scleral
expansion bands (SEB(.

58. •The efferent
•Edinger-Westphal
nucleus - oculomotor
nerve - ciliary ganglion
- short ciliary nerve -
iris sphincter and the
ciliary
muscle/zonules/lens of
the eye
•oculomotor neurons -
oculomotor nerve -
medial rectus,
converge the two eyes.

59. Presbyopia
Presbyopia is a condition of
physiological
insufficiency of accommodation
leading to a progressive fall in near
vision.

60. Symptoms
•Difficulty in near vision.
•Patients complaint of difficulty in
reading small prints
•Asthenopic symptoms due to fatigue
of the ciliary muscle are also
complained after reading or doing
any near work.

61. Presbyopia Rx

62. •Intraocular refractiveprocedure
•Refractive lens exchange
•Phakic refractive lens
•Monovision with IOLs
•Scleral based procedures
•Anterior sclerotomy with tissue barriers
•Scleral spacing procedure
•Scleral ablation with erbium : yag laser

63. Clinical features
•Blurred vision atnear
•Photophobia or a 'dazzling' effect
•Diplopia
•Micropsia: objects may appear
smaller than they are due to a false
sense of distance
•Enlarged pupil.

64. Symptoms
Blurred vision at near is uncommon
Blurred vision at distance
Headaches
Eyestrain
Photophobia
Difficulty changing focus from distance
to near
Diplopia

65. Treatment
•It has a good prognosis.
•Refractive error should be corrected
after carefully performed cycloplegic
refraction.
•Near work should be stopped for
some time, after that it should be
done with proper illumination
conditions.

66. Causes
• Drug induced spasm of
accommodation is known to occur
after use of strong miotics.
• Spontaneous spasm of
accommodation: attempt to
compensate for a refractive
anomaly.
• Occurs when excessive near work
is done with bad illumination, bad
reading position, state of neurosis,
mental stress or anxiety.

67. Clinical features
• Defective vision: due to induced
myopia.
• Asthenopic symptoms
• Precipitating factors like marked
degree of muscular imbalance,
trigeminal neuralgia, a dental
lesion, general intoxication.

68. accommodation
•The ability of the eye to
increase its converging power
while viewing a near object

70. Radius of curvature:
Anterior lens surface= 10mm
Posterior lens surface =6mm
Contraction of ______ muscle
Slackening of zonules
Elasticity of the lens capsule

71. Associated
phenomena
•Converge
nce
•Miosis
•Synkinesi
s

72. presbyopia
As age advances…
• Lens becomes harder
• Ciliary muscle becomes weaker
• It becomes more and more
difficult to see near objects
clearly
• The near point recedes
gradually

73. treatment
Near vision addition
Convex lens
40years- 1.0 D
45years- 1.5 D
50years- 2.0 D
55years- 2.5 D
60years- 3.0 D
Better to undercorrect than
overcorrect

74. •Contact lenses for presbyopia

75.  Surgical procedures
Conductive keratoplasty:
radiofrequency energy is used to
reshape the cornea of the non dominant
eye
presbyLASIK

76. Anisometropia
•Condition in which the refractive status of
the two eyes are unequal

77. • Contact lenses:
• Higher degrees of anisometropia
• Very useful in young children with
high anisometropia to prevent
amblyopia

78. • IOL
implantation:
• when unilateral
aphakia is the
cause of
anisometropia
• Refractive
corneal surgery:
• LASIK

79. • Mono-vision can be used
in selective few patients
who have one eye
hypermetropic or
emmetropic and the
other eye myopic
• one eye (dominant eye)
can be used for distant
vision and the other for
near vision

80. Diverging Lens
•
Answer: Page 98, Q. 1-3

81. Lens Combinations
•What is the power, focal
lengths?

82. Activities
Page 112, Q. 2-3, 5
•Testing your knowledge

83. Devices: Camera

84. Eye Ball

85. VERGENCE
• All naturally occurring sources of
light are divergent
• Light rays traveling parallel have
zero vergence
• Light rays that focus on a point are
convergent
• The unit of measurement of
vergence is the diopter
D= Vergence (Diopters)=___________1_____________
Distance from the source in meters

86. REFRACTION
•Refraction of light occurs when
light passes from one medium
to another of different refractive
index (ie. density(

87. Fovea
Light rays

88. Ametropia (Refractive
error(
•Mismatch between axial length
and refractive power.
•Parallel light rays don’t fall on
the retina (no accommodation(
•Nearsightedness (Myopia(
•Farsightedness (Hyperopia(
•Astigmatism
•Presbyopia

89. Accommodation
•Emmetropic eye
•object closer than 6 M send
divergent light that focus behind
retina , adaptative mechanism of
eye is increase refractive power
by accommodation
•Helm-holtz theory
•contraction of ciliary muscle --
decrease tension in zonule fiber
s --elasticity of lens capsule mo
ld lens into spherical shape --gr
eater dioptic power --divergent
rays are focused on retina

94. Myopic photorefractive
kertectomy • PRK can effectively treat
low to mod myopia or
hyperopia +/- astigmatism.
• Performed as outpt with
topical anesthesia.
• First, the corneal
epithelium in the area to
be ablated is removed to
expose Bowman’s layer
and the underlying corneal
stroma (spatula, laser).
• Excimer laser then applied
as directed by the corneal
topography-driven
computer program.
• Topical antibiotics,
steroids, and NSAIDs
applied, along with a
bandage contact lens

95. PRK
• In the post-op period, pt may experience tearing,
photophobia, blurred vision, and discomfort due
to abrasion of central epithelium.
• This can be controlled with topical steroids and
NSAIDs.
• Pts occ. require systemic analgesia for severe
pain
• BCTL removed once epithelial defect healed
(avg 3-4 days).
• Abx continued several more days, and steroids
for up to 3 months post-op.
• Visual acuity improves once the epithelial
defect heals, but fluctuates for a few months
and finally stabilizes at ~3 months.
• Glare, halos, and dry eye symptoms common the
first month post-op, usually
diminishing/disappearing by 3-6 months.

96. Laser Sub-Epithelial
Keratomileusis
• LASEK can treat mild to moderate myopia and
hyperopia +/- astigmatism.
• Can be performed as an outpt with topical
anesthesia
• The corneal epithelium is incompletely incised
using a microkeratome with a 70 micron deep
blade.
• A hinge is left at the 12 o’clock position.
• Dilute alcohol (20%) drops are applied to the
exposed tissue and left for ~30 seconds. The
area is then washed with water and allowed to
dry. The excimer laser is applied as in PRK to
the sub-epithelial stroma.
• The epithelial flap is repositioned afterward.

97. LASIK
• LASIK can treat mild, moderate, and high myopia
and hyperopia +/- astigmatism.
• Can also be performed as an outpt with topical
anesthesia
• LASIK is now the most commonly performed
refractive surgery in the world.
• A suction ring is applied to the anesthetized cornea
and a microkeratome is used to raise a corneal flap
of ~160microns thickness (25-30% of the corneal
thickness), hinged at the 12 o’clock position.
• The suction is turned off and the flap is lifted aside,
exposing stromal tissue
• The excimer laser is applied as with PRK and
LASEK, controlled by the topography-driven
computer software, to reshape the cornea.
• The flap is replaced on the stromal bed without
sutures or a BCTL, as the endothelial pumps create
a driving force to keep the flap in position.

98. LASIK
• The use of the suction ring helps hold the
cornea steady and provides for a uniform
cut by the microkeratome.
• Flaps can be formed by an automated
process involving a blade guide on the
suction ring to guide a turbine-driven
microkeratome, producing a very smooth,
regular cut
• Patients usually sent home on topical
antibiotics, steroids, and NSAID drops. Pt
is usually seen ~POD 1, and 7, then at 1, 3
and 6 months.
• Benefits include little pain, quick
recovery of vision, and potential to treat
higher levels of myopia. LASIK
enhancements are also easily performed.

99. LASIK
Complications
• Potential complications:
• Intra-operative flap complications: microkeratome
complication with a higher rate with surgeon inexperience
• Post-operative flap complications
• Flap-bed interface epithelialization: that epithelial growth
at the interface could significantly be reduced by irrigating
the stromal surfaces and using a BCTL for one day.
• Irregular astigmatism
• Infection:
• Diffuse lamellar keratitis (DLK): (AKA Sands of Sahara
syndrome) Wavy inflammatory reaction at LASIK flap
interface 1-3 days post-op of unknown cause. Treatment
involved high-dose topical steroids or lifting the flap to
irrigating the interface.
• Progressive corneal ectasia: progressive corneal thinning
and steepening with worsening irreg. astigmatism thought
to result from too thin a stromal bed after LASIK. Most
believe stromal bed thickness should be at least 250
microns.

100. Symptoms
• cannot see things at a
distance as well.
• Can not see writing from
the black-board
Blurred distance
vision
(The term “myopia”
comes from this
squinting; the Greek word
“myein”
Eye strain or
headaches
from trying to focus

101. TreatmentTreatment :
-concave lenses (minus lenses)
-Contact lens
-In certain special cases removal of the
crystalline lens
( Χ retinal detachment)
-implanting an anterior chamber intraocular
lens (diverging lens) anterior to the natural lens to
reduce refractive power

102. Ametropia
1. Abnormal length of the
globe__axial ametropia.
2. Abnormal curvuture of the cornea
or lens curvutural ametropia.
3. Abnormal refractive indix of the
media __ index ametropia.
4. Abnormal position of the lens.
position Ametropia

103. Uncorrected, light focuses in front of
fovea
Corrected by divergent lens, light focuses on
fovea

104. LASIK Complications
• Potential complications:
• Intra-operative flap complications:
• Post-operative flap complications
• Flap-bed interface epithelialization:
• Irregular astigmatism
• Infection:
• Diffuse lamellar keratitis (DLK):.
• Progressive corneal ectasia:

105. Myopic photorefractive
kertectomy
• PRK can effectively
treat low to mod
myopia or hyperopia +/-
astigmatism.