Hyperopia is a refractive error in which parallel rays of lightentering the eye reach a focal point behind the plane of the retina, while accommodation is maintained in a state of relaxation.
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| Fig: Uncorrected Hypermetropia |
In a hypermetropic eye the focal point is located behind the retina which may be brought to the retina by accommodation and therefore the patient can see the distant objects clearly by exerting accommodation. In the process they exert all of the accommodative ability to see distance object, and nothing is left for near vision. Hence they cannot see near object.
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| Fig: Corrected Hypermetropia |
Hypermetropia is of three types:
• Latent Hypermetropia
• Manifest Hypermetropia
• Absolute Hypermetropia.
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| Types of Hypermetropia |
• Latent Hypermetropia is totally by eye’s own accommodative ability, can be detected only by cycloplegia.
• Manifest hypermetropia can be corrected either by patient’s own accommodation or by plus lens. When it is compensated by patient’s own accommodation, it is called Facultative Hypermetropia, and when it is not corrected by accommodation, it is called Absolute Hypermetropia.
• Total hypermetropia is the sum of manifest and latent hypermetropia. Treatment of hypermetropia depends upon patient’s ability to compensate for close work and symptoms. In case of young patients, if it is not associated with accommodative strabismus, it may be avoided and in case of old patient, hypermetropia is corrected to improve near vision. Fluctuating accommodation can confuse the retinal focus presented by each change of lens combination before the eyes; accommodation must be maintained at the relaxed state.
Therefore, fogging method of subjective refraction is preferred for determining the refractive correction to prescribe, especially for the older child or adult patient. Remember to put the reducing plus before and then take out old plus from the trial frame.
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