Hyperopia

Introduction

Hyperopia denotes a visual condition of behind foveal focusing of distant images the optical system of the eye when accommodation is relaxed. Research reports that hyperopes outnumber myopes in the population.

Presentation
The presentation of hyperopia depends on age and magnitude. Younger low hyperopes typically present with good visual acuity and near vision adequacy. This is attributed to the efficient accommodation reserves in the young. This cannot be said of the moderate and higher young hyperopes. The moderate young hyperopes may present with eye strains (which is sometimes described as pain) on near work even with good visual acuities and near vision adequacy. High young hyperopes present with subnormal visual acuities and near vision inadequacies. With high young hyperopes, the accommodative reserves are inefficient to cope with the high magnitude of hyperopic defocus.
The older hyperopes (35 and above) present may present with reduced visual acuities and near vision inadequacy.

Manifest or Latent? Manifest hyperopia is that hyperopia which is revealed on subjective refraction whether visual acuities are normal or subnormal. There are two types of manifest hyperopia; Facultative and Non-facultative hyperopia. The facultative form which can be compensated by accommodation and presents in the younger population due to the efficient accommodative reserves. Facultative hyperopia presents with normal visual acuities due to accommodative compensation. For the older, the non-facultative form which cannot be corrected by accommodation presents often because of the lowered accommodative reserves. In the non-facultative form, visual acuities are also reduced due to decompensation by accommodation.

Latent hyperopia is due to constant contraction of the ciliary muscles of accommodation (spasm). This commonly presents in younger hyperopes. It is never exposed on subjective refraction except through induced cycloplegia with topical cycloplegic drugs and to some extent, with fogging retinoscopy (the eye not scoped is first fogged with plus lenses till an against motion is seen in one meridian before scoping the opposite eye).

The confusion between latent and facultative hyperopia
It seems easy to confuse both. Reason been that they present in the young and present similarly with good visual acuities and sometimes, complaints of strains on near work. If on adding plus spheres, good visual acuities remain up till a point of first sustained blur, then the hyperopia up to the point of first sustained blur has previously been corrected by accommodation and is the measure of facultative hyperopia. The magnitude of the facultative hyperopia is the power of the plus lens that causes the first sustained blur. Latent hyperopia is never exposed as such.

Forms of hyperopia are not mutually exclusive
This means that latent and manifest hyperopia do occur at together. The same holds for facultative and non-facultative hyperopia.

Reference
American Optometric Association 2008, Care of the patient with hyperopia, viewed 2 March 2015, <https://www.google.com.ng/url?sa=t&source=web&rct=j&ei=MU37VL_HCYbP7Qa7joDoBQ&url=http://www.aoa.org/documents/optometrists/CPG-16.pdf&ved=0CB0QFjAA&usg=AFQjCNHjTbxzaXld8-AkJ_owHlCDthE3EQ&sig2=9MaAbI3miBtcmIJ0euquag>