This document discusses different types of myopia (nearsightedness). It defines myopia as a refractive error where parallel rays of light from infinity are focused in front of the retina. It describes the different classifications of myopia including by etiology (cause), degree, age of onset, and association with other ocular conditions. For example, it distinguishes between congenital myopia present from birth and simple/developmental myopia which begins later in childhood. It provides details on examinations and treatments used to diagnose and manage different levels of myopia.
3. Refractive error
Parallel rays of light coming from
infinity are focused in front of the
retina
Accommodation is at rest
4. 2x risk 5-6x risk
<1.5 hours
>3 hours
2.6x risk
⦿ Children most at risk=
Outdoor time Nearwork
⦿ Children with
emmetropia spend 3.7
hoursper week more
outdoors than those
with myopia 6
40- 80 minutes ↓23% to 50%
13
⦿ Light level
› Light towards the UV
end of the spectrum
slows eye growth and
myopia
8. Congenital Myopia
School Myopia(<20 yrs of age)
Early Adult-Onset Myopia(20-40 yrs of age)
Late Adult-Onset Myopia(>40 yrs of age)
9. CONGENITAL MYOPIA
Increase in axial length
Increase in Overall globe size
Since birth, diagnosed at age 2-3 years
If unilateral, as anisometropia, may develop amblyopia, strabismus
Usually 8-10 D, remain constant
Bilateral- difficulty in distant vision, hold things very close
10. Physiological error not associated with any disease of the eye
Etiology :
Normal biological variation in development of eye
Inheritence
Associated factors
Role of diet
Theory of excessive near work
11. Clinical picture
Rarely present at birth
Rather born hypermetropic, become
myopic
Begins at 7-10 years, stabilizing
around mid teens
Usually around 5D, never exceeds 8D
Signs
Large and prominent
Deep AC
Large, sluggishly reacting pupils
Normal fundus, rarely crescent
Usually doesn't exceed 6-8D
Retinoscopy under full cycloplegia
12. PATHOLOGICAL / DEGENERATIVE /
PROGRESSIVE MYOPIA
Rapidly progressive associated with degenerative changes in the eye
Etiology
Rapid axial growth of the eyeball outside the normal biological variations of
development
Role of heredity
Role of general growth process
13. Genetic factors General growth process
More growth of retina
Stretching of sclera
Increased axial length
Degeneration of choroid
Degeneration of retina
Degeneration of vitreous