Hypermetropia

Hypermetropia
BY
RAIN HEALTH CARE
EYE & LIFESTYLE DISEASE CONSULTATION & MANAGEMENT CENTER

WHAT IS HYPERMETROPIA
TYPES OF HYPERMETROPIA
ETILOGY OF HYPERMETROPIA
CLINICAL FEATURES OF HYPERMETROPIA
HYPERMETROPIA PPT

1. HYPERMETROPIA Hypermetropia is an error of refraction in which parallel rays of light from infinity come to a focus behind the retina when accommodation is at rest.

2. Types of hypermetropia Axial hypermetropia  Curvature hypermetropia  Index hypermetropia 

3. Axial hypermetropia Axial hypermetropia When the anterior/posterior length of the eyeball is shorter than normal. (Normal axial length is 24mm). A decrease of 1mm in axial length produces a hypermetropia of 3.0D.  ** all newborns are almost hypermetropic approximately +2.5D. This is due to the shortness of the globe and is physiological . ** it may also occur pathologically when the retina is displaced forward {RD, CSR, ORBITAL TUMORS, RETINAL TUMOR } ** In micro or nano ophthalmos where the axial length is less than 20.0 mm there is high hypermetropic.

4. Curvature hypermetropia Curvature hypermetropia When the curvature of the cornea or lens is flatter than normal. An increase of 1mm in its radius of curvature produces a hypermetropia of 6.OD. 

5.  Index hypermetropia  Index hypermetropia When the refractive index of the media is less than normal  - Corneal refractive index - 1.37  - Refractive index of the cortex of lens - 1.38  - Refractive index of the nucleus of lens - 1.40 

6. Clinical types of hypermetropia 1. Congenital hypermetropia  2. Simple or developmental hypermetropia  3. Acquired hypermetropia Congenital hypermetropia: This is rare. It is usually associated with other congenital anomalies of the eyeball like microphthalmos .  Simple or development hypermetropia: It is the most common type. A newborn baby is hypermetropic but with age, the eyeball grows in size and the hypermetropia are gradually diminished. If the growth of the eyeball is retarded then hypermetropia persists. Acquired hypermetropia: This is found in aphakic conditions, commonly following extraction of the lens. This hypermetropia is usually high about + 10.0 D.

7. Depending on clinical presentation hypermetropia can be of different types 1. Simple hypermetropia: This is due to normal biological variation in development of eyeball. This is the most common type of hypermetropia.  2. Pathological hypermetropia: This is due to certain factors which are not in the normal biological variations, e.g. posterior subluxation of lens (positional hypermetropia), acquired cortical sclerosis (index hypermetropia), under-correction of refractive error (consecutive hypermetropia) and congenital absence of the lens (aphakia).  3. Functional hypermetropia: It results due to paralysis of accommodation, e.g. third nerve paralysis.

8. Depending upon act of accomodation The hypermetropia which is seen after complete paralysis of accommodation, after the application of atropine TH=MH+LH  Latent hypermetropia:  It is the amount of hypermetropia which is corrected by the normal physiological tone of the ciliary muscle. It is strong at a young age and slowly declines with age.  Manifest hypermetropia:  The remaining portion which is not corrected by the normal physiological tone of the ciliary muscle is called manifest hypermetropia. It is hypermetropia that remains uncorrected in normal circumstances. That is when accommodation is not being actively used, or, in other words, it is the total hypermetropia minus the latent hypermetropia. 

9. This manifest hypermetropia is again made of two components.  1. Facultative hypermetropia  2. Absolute hypermetropia  1. Facultative hypermetropia:  It the part of hypermetropia, which can be corrected by an additional effort of accommodation or excessive the strain of the ciliary muscle.  2. Absolute hypermetropia:  Absolute hypermetropia is the part of hypermetropia which cannot be overcome by active exertion of accommodation. 

10. Symptoms of hypermetropia 1. Headache  2. Eyestrain  3. Distance blurred vision  4. Difficulty in doing prolonged close work 

11. Treatment of hypermetropia 1. By prescribing correct convex lenses  2. Contact lenses  3. Lasik

12. Complication of hypermetropia Uncorrected hypermetropia leads to esophoria, which later on may develop into esotropia. convergent squint hypermetropia with esophoria - To give full correction  Hyperopia with exophoria - To give under e under correction Hypermetropic individuals often have a shallow anterior chambers. They have an increased predisposition to develop narrow-angle glaucoma . Lid diseases: Repeated rubbing of eyes in  hypermetropic  blurred vision may produce blepharitis, stye, or chalazion . amblyopia- anisometropic, strabismic,ametropic

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