This document defines and describes myopia (nearsightedness). Myopia occurs when light rays focus in front of the retina rather than directly on it. There are several types of myopia, including congenital (present at birth), simple/developmental (onset between ages 8-12), pathological (extreme nearsightedness causing eye shape changes), and acquired (developed through near work over time changing lens power). Treatment options include eyeglasses, contact lenses, and orthokeratology which uses special lenses to temporarily reshape the cornea.

1. Myopia
By: Tahir Shaukat
Optometry Club
PowerPoint: Alaa Al-Aqel

2. Tableof
Content:
 Definition.
 Optics of Myopia.
 Types.
 Clinical types.
 Treatment .

3.  Definition:
Myopia or short sightedness; is a type of
refractive error in which parallel rays of light
coming from infinity are focused in front of
the retina when accommodation is at rest.

4. Opticsof
Myopia:
 Optical system of myopic eye is too powerful for its axial length.
 Image of distant object on the retina is made up off the circles of
diffusion formed by the divergent beam, since the parallel rays of
light coming from infinity are focused in front of retina. As shown
below.
 Far point of myopic eye is a finite point in front of the eye.
Therefore a near object situated at the far point is focused without
an effort of accommodation.

5. Myopia
Classification:
Etiological classification.
Clinical classification.
Age of onset.

7. Congenital myopia
Simple or
developmental myopia
Pathological or
degenerative myopia
Acquired myopia
Clinical
classification

8. CongenitalMyopia:
 Congenital myopia is associated with an increase in axial
length and overall globe size. It is seen more frequently in
children who were born prematurely or with various birth
defects, such as Marfan syndrome and homocystinuria.
 Present since birth.
 Usually diagnosed by the age of 2-3 years.
 High degree of error.
 Error is about 8-10 D, which mostly remains constant.
 Most of the time, the error is unilateral and manifests as
anisometropia.
 It may be associated with congenital convergent squint and
other congenital anomalies like cataract, microphthalmos,
megalocornea and congenital separation of retina.

9. SimpleMyopia:
 Simple myopia also known as physiological
myopia is the commonest variety.
 It is not associated with any disease of eye.
 Result from normal biological variation in
development of eye.
 Onset occurs at school going age i.e.
between 8 and 12 years of age, so also
called school myopia.

11. Pathological
Myopia:
 Pathological myopia is an extremely high
amount of nearsightedness that causes a major
alteration of the shape or globe of the eye,
which may lead to profound vision loss. In the
United States, it occurs in about 2% of the
population and is the seventh leading cause of
legal blindness.

13. Acquired
Myopia:
 Myopia, according to the lenticular theory
is acquired through adaptive change in the refractive
power of the crystalline lens and in the related systems,
caused by continued accommodation to near-work.

17. Treatment:
Eyeglasses and contact lenses are the best treatment options
while nearsightedness is still changing. Another option is
orthokeratology (ortho-k). This is the fitting of specially
designed contact lenses that reshape the cornea of the eye to
temporarily correct mild to moderate myopia.

18. Thank you