MYOPIASaad Bin Zafar Mahmood

Emmetropia

24-25mm

43 diopters

18 diopters

Accomodation at rest

A form of refractive error in which parallel rays of light entering the eye are focused in front of retina with accomodation being at rest

Myopia - Defination

Curvature

Axial length

Refractive index

Positional

Etiology

Congenital

Simple

Degenerative

Types of myopia

Unilateral / Bilateral

Stationary

Associated with convergent squint

Congenital myopia

Most common refractive error

Age of onset

Moderate severity

No degenerative changes

Simple myopia

Progressive in nature

Age of onset

Severe

Hereditary in nature

Degenerative myopia

Pathogenesis

Degenerative changes in sclera

Increase in axial length of eyeball

Elongation and stretching of sclera

Changes in choroid and retina

DECREASE VISION

Myopic Crescent

Lacquer CracksBreaks in Bruch’s membrane

Sub retinal neovascularization

Sub retinal hemorrhage

Foster – Fuch’s spots

Posterior staphyloma

Macular hemorrhage

Posterior staphyloma

Retinal detachment

Glaucoma

Complications

Distant blurred vision

Half shutting of eyes

Divergent squint

Clinical features - Symptoms

Prominent eyeballs

Anterior chamber is deep

Ultrasongraphy

Fundus examination

Signs

Concave lenses◦ Children◦ Adults

Contact lenses

Medical treatment

Cornea

For high refractive errors

◦ Clear Lens extraction

◦ Phakic posterior chamber implant

Surgical treatment

Radial Keratotomy

◦ Radius of the curvature of cornea is reduced (flattened)

◦ Series of radial incisions in peripheral cornea

◦ Can correct upto 4 diopters

◦ Less popular these days due to PRK and LASIK

Cornea

Photorefractive keratectomy

◦ Laser procedure

◦ Central corneal surface is ablated

◦ Results in flattening of cornea

◦ A 10um ablation corrects a 1 dipotre of myopia

LASIK (Laser in-situ keratomileusis)

Step 1

Step 2

Step 4

Step 3

Absence of post-operative pain

Less haze

Rapid recovery

Advantages of LASIK

Hybrid of PRK and LASIK

It involves separation of epithelium

Difference with LASIK is the thickness of epithelium

LASEK (Laser epithelial keratomileusis)