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Far Sightedness
HYPERMETROPIA OR LONG-SIGHTEDNESS OR FARSIGHTEDNESS
What is hypermetropia?

It is a refractive error wherein the parallel rays of light coming from infinity, after refraction through the eye, come is a point focus behind the retina, when the accommodation is at rest.
 
 
 
What causes Hypermetropia?
 
(1) Axial hypermetropia:
 
Failure of the eye ball to grow to full size (at birth and length is 16.5 mm, adult size is24mm).
Pathological conditions like
 
(a)   Orbital tumors pressing the eye ball forward.
(b)   Retinal detachment.
 
(2) Curvature hypermetropia:
 
If the cornea is flatter than normal, hypermetropia results.
  • Cornea plana (a congenital condition)
  • After cataract surgery.
 

 
 
(3) Index hypermetropia:
(a) In old age: refractive index of the lens increases leading to hypermetropia.
 
(b) Cortical cataract.
(4) Abnormal position of lens:
  • Posterior dislocation of the lens
  • Aphaki
 

What are the CLINICAL FEATURES in hypermetropia?

(1)   Defective near vision: Rays of light coming from near object are divergent. So, they come to a point focus much behind the retina.

(2)   Accommodative eyestrain: - In order to see objects clearly eye accommodates continuously, even for distant vision. This cause eyestrain.

(3)   Accommodative Esotropia: - Accommodation and emergence are inter-related. Excessive accommodation finally leads to convergent squint.

(4)   Accommodation (Pseudo myopia): - Due to excessive accommodation rays of light may over coverage and cause myopia.
What are  the TYPES OF HYPERMETROPIA?
When the ciliary muscle is totally at rest (paralysed or atropinised), hypermetropia is called (1) Total hypermetropia. Normally a small part of this hypermetropia is corrected by the physiological tone of the ciliary muscle. This portion is called (2) latent hypermetropia. The remaining part of the hypermetropia is called (3) Manifest hypermetropia.
Manifest hypermetropia: - A part of manifest hypermetropia is corrected by accommodation. This portion is called (4) Facultative hypermetropia. Remaining part of manifest hypermetropia which cannot be corrected by accommodation is called (5) Absolute hypermetropia.
 
What are the FINDINGS IN CLINICAL PATHOLOGY?

(1)   Small eyeball.

(2)   Cornea may be smaller.

(3)   Anterior chamber shallow: by 40 years of age, this eye is in the danger of developing primary angle closure glaucoma.

(4)   Lens has the normal size.
 
What are the FUNDUS FINDINGS?

      (1)   Small hyperaemic disc with hazy borders – resembling optic neuritis à This is a pseudo neurotic appearance

        (2)   Increased reflexes of fundus background à called as wet silk fundus (shot silk fundus).
 
How to Diagnose?
Cycloplegic retinoscopy using short acting cycloplegics like cylcopentolate 1% in adults and strong cycloplegic like atropine eye ointment 1% in children
 
What is the TREATMENT?

(1)   Convex lens (spectacle

(2)   Contact lens

(3)   Surgery: Surgery is done in high hypermetropia like aphakia Epikeratophakia is the surgery. Not done frequently.

a)      Keratomaleasis

b)      Holum Laser PRK secondary IOL implementation.
 
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