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Myopia (Shortsightedness) (Etiological Calssification (Axial Myopia…
Myopia (Shortsightedness)
Etiological Calssification
Axial Myopia ⬆️Anteroposterior length of lens
Curvatural myopia ⬆️ Curvature of cornea
Positional Myopia ➡️Anterior placement of Lens
Index Myopia ⬆️ Refractive index of lens associated with Nuclear sclerosis
Myopia due to spasm of accommodation
Grading
Low < 3D
Moderate 3 to 6D
High > 6D
Clinical Varities
Congenital
Diagnosed at age of 2-3 years , Present since birth
Unilateral Anisometropia
8 to 10D of error
Convergent squint
association with Cataract , Megalocornea,Aniridia
Simple / Developmental
Commonest
Physiological error
School Myopia ( Between 8 to 12/years of Age)
Etiology : Axial / Curvatural
Diet
Heredity
Short sightedness
Half shutting of eye
Asthenopic symptoms
Prominent Eyeballs
Deeper AC
Large Pupil
Rate of Magnitude of Error ➡️ ⬆️ -0.5 + - 0.30D every year
Pathological Myopia
Degenrative / Progressive
Defective Vision
Muscae Volitantes ( Floating Black Opacities in front of eyes )
Night blindness
Signs
Prominent Eyeballs
Large Cornea
Deep AC
Large & Sluggish Pupil
Fundus Examination
Large & Pale Optic disc
Characteristic Myopic crescent at Temporal edge
Super traction crescent on Nasal side
Degenerative changes in retina & Choroid
Chotioretinal atrophic patches at Macula
Foster Fuch Spot ( Dark Red Circular Patch due to subretinal Neovascularization & Choroidal Haemorrhage ) present at Macula
Cystoid Degeneration at periphery
Lattice degeneration / Snail track Lesions / Retinal holes & tears
Total retinal atrophy in advanced cases
Posterior staphyloma due to ectasia of Sclera
Posterior vitreous detachment appears as Weiss reflex
Subnormal ERG
Complications
Retinal detachment
Choroidal & Vitreous haemorrhage
Strabismus fixes convergence
Complicated cataract
Treatment
Optical Treatment
Minimums acceptance providing Maximum vision should be prescribed ( Basic Rule )
Concave spectacle lens
Contact lens in case of High Myopia as they avoid Peripheral distortion & minification of Images
Surgical Treatment
General measures
Balanced Diet rich in vitamins&Proteins
Visual Hygeine
Early managment the of associated debilitating disease
Low vision aids in advanced degenerative changes
Prophylaxis ( Genetic Counselling )