An elderly patient of about 5 years of age complains of difficulty in reading, both finer and bigger prints and has to hold the reading material very close to the eyes. This is HYPERMETROPIA or far sightedness.
In hypermetropia, the image is formed on a plane behind the retina and the patient has to accommodate very powerfully for seeing the near objects. This is due to the defective shape of the globe. To correct this condition, the patient will need to use convex lenses.
SYMPTOMS OF HYPERMETROPIA
The symptoms vary depending upon the age of the patient and the severity of refractive error. Patient may be asymptomatic. Small amount of refractive error in young patients is usually corrected by mild accommodative effort, without producing any symptoms.
Symptomatic patients may present with:
When hypermetropia is fully corrected : At times the hypermetropia is fully corrected (thus vision is normal) but due to sustained accommodative efforts the patient develops asthenopic symptoms.
- Asthenopia (eyestrain).
- Frontal or fronto-temporal headache.
- Mild aversion to light.
These symptoms worsen as the day progresses and are aggravated by prolonged near work.
When hypermetropia is not fully corrected: When hypermetropia is not fully corrected by the voluntary accommodative efforts, then the patient complains of defective vision more for near than distance, due to sustained accommodative effort. Patient present with:
- Defective vision more for near.
When hypermetropia is high: When hypermetropia is high (more than 4 D), the patients usually do not accommodate and they suffer with:
- Marked defective vision for both near and distance.
When there is more of absolute hypermetropia: With ageing the eye move from latent and facultative hypermetropia to greater degrees of absolute hypermetropia. This leads to progressive defective vision. Patient present with:
- Blurring of vision at a younger age than in emmetrope.
When there is Spasm of accommodation: Spasm of accommodation may induce pseudo-myopia. It may be detected by cycloplegic refraction. It presents as:
- Intermittent sudden blurring of vision.
In general, child may also present with lid diseases (like blepharitis, stye or chalazion), convergent squint or amblyopia.
CAUSES OF HYPERMETROPIA
Hypermetropia may be:
- Axial hypermetropia: Axial hypermetropia is the commonest type. The total refractive power of the eye is normal but there is axial shortening of the eyeball. About 1 mm shortening of the antero-posterior length of the eye results in about 3 Dioptres (D) of hypermetropia.
- Curvature hypermetropia: Curvature hypermetropia is that condition in which curvature of the cornea, lens or both is increased (flatter) than the normal, resulting in change in refractive power of the eye. About 1 mm increase in radius of curvature results in 6 D of hypermetropia.
- Index Hypermetropia: Index Hypermetropia occurs due to change in refractive index of the crystalline lens with age.
- Positional hypermetropia: Positional hypermetropia results from posteriorly placed crystalline lens of the eye.
- Absence of crystalline lens: Absence of crystalline lens either congenital absence or acquired (following surgical removal or posterior displacement) leads to aphakia. There is high hypermetropia in aphakia.
It may also be functional, as is seen in presbyopia or may be induced by cycloplegic drugs.
HOMOEOPAHIC TREATMENT OF HYPERMETROPIA
Argentums nitricum is useful in restoring power to weakened ciliary muscles. Aching and tired feeling in the eyes, better by pressing or closing them. Eye strain develops due to sewing and working in a warm room.
Calcarea carbonica is easy fatigue of the eyes and dimness of vision, as if looking through a mist, by constant reading and writing. Lachrymation early in the morning and the patient is sensitive to light. Far sighted.
Carbo animalis, objects seem to be far off and there is dimness if vision when reading, better rubbing the eyes. Useful un senile cataract. Sensation as if something lay above the eyes. Therefore finds it difficult to look up. The patient is very weak and constitutionally very debilitated.
China officinalis eyes are painful while reading and writing. Pressure in the eyes. As if from drowsiness. Distortion of eyeballs. Anaemia of the retina causing night blindness. Often, there is ciliary neuralgia.