MYOPIA BY INDRAJIT BISWAS

1. MYOPIA
This is also known as ‘Short Sightedness’. It is defined
as a condition of refraction in which parallel rays of
light coming from infinity are focused in front of the
retina with accommodation at rest. This is because
the power of the eyeball is more than +60D.

2. Types of Myopia
• Depending upon the mechanism of
production, myopia may be of different types:
1. Axial myopia
2. Curvature myopia
3. Index myopia
4. Positional myopia
5. Excessive accommodation as occurs in a
spasm of an accommodation causes myopia.

3. Depending upon clinical presentation
1. Congenital myopia:
• The child is born with an elongated eye.
• The refraction may be up to -10D.
• Typical fundus changes are seen.
• Progression is rare.

4. 2. Simple myopia
• The most common is clinical types.
• Does not progress much after adolescence.
• May be up to -5D to -6D.
• No degenerative changes are seen in the
fundus, although peripheral retinal
degeneration may be seen in later life.
• Associated with good vision with a good
prognosis.

5. 3. Pathological myopia
• Myopia appears in childhood (5-10 years of age)
and increasing steadily with age up to 25 years or
beyond.
• The final amount of myopia may be -15D to -25D
or more.
• There are typical degenerative changes in the
fundus.
• Strongly hereditary and more common in
females.
• prognosis is usually poor.

6. Acquired myopia
• This occurs due to exposure to various
pharmaceuticals, increase in glucose level,
nuclear sclerosis, and increase in curvature of
the cornea in conditions such as corneal
ectasias.
• The other types of acquired myopia are:
1. Pseudo myopia
2. Night myopia
3. Space myopia

7. Symptoms
• Blurred vision or difficulty in seeing distant
objects (Children often cannot read the
blackboard, but easily read a book). They tend
to go near objects to see clearly.
• Eyestrain
• Headaches (uncommon)
• Squinting tendency

8. Tests
• 1. Visual acuity, both at a distance (Snellen’s), and close up
(Jaeger)
• 2. Refraction test to determine the refractive power
accurately
• 3. Cycloplegic refraction may be required in few conditions
to confirm the final prescription
• 4. Color vision test to exclude color defect.
• 5. Muscle balance test
• 6. Slit-lamp examination of the eyes
• 7. Measurement of the intraocular pressure of the eyes
• 8. Retinal examination

9. Treatment of Myopia
• Myopia is corrected by appropriate concave lenses
either in form of spectacles or contact lens.
• Surgical correction of myopia can be done by
photorefractive surgery or exchange of clear lens.
Contact lenses are cosmetically better suited with
minimal aberrations and maximum visual field,
especially in high myopes. However they need
motivation and better care on part of the patient.
• LASIK laser surgery is gaining popularity day by day. But
it has its own limitations, as very high myopes, are
sometimes not fit for surgery due to poor corneal
thickness or keratoconus.

10. THANK YOU