Abstract

Background: Many of visual functions are usually impaired by serious retinal diseases. With different speed of progression, the point of sharpest vision is being damaged and visual acuity as well as contrast sensitivity and fixation stability declines. Instead of the damaged fovea the new preferred retinal points are arising and taking over its function as the referential position for the whole motoric system. The development of such new points of fixation can evoke condition which is similar to fixation disparity. Of course, binocular vision (e. g. binocular summation of visual acuity) is markedly deteriorated too, together with the diminished central fusion due to inequality of the both, differently affected retinal pictures. It's obvious that former binocular vision disturbances (e.g. latent strabismus) could now become decompensated. The purpose of this study is to evaluate the efficiency of the binocular prismatic correction in patients with central retinal impairment that allows the restoration of the best possible correspondence of the preserved retinal areas. Methods: Two groups of volunteer participants were established. There were 17 patients with central retinal impairment in the group A and 17 people with healthy eyes in the second control group (Group A) in about the same age. The visual acuity and monocular and binocular vision at a far and near distance was examined and the best correction determined. Two pairs of spectacle correction were completed, one pair (glasses for far and glasses for near vision) with full sphero-cylindrical correction and full prism correction and the other pair only with full sphero-cylindrical correction without prisms. The participants tested each pair for 1 month and the binocular visual acuity and summation were evaluated and subjective notions were noted. Results: The outcomes were evaluated both within each group and between the groups. It was found out that the improvement of binocular visual acuity (compared to the monocular of the better eye) was approximately the same in both groups when using the prismatic correction. On the other hand, participants with central retinal impairment achieved markedly lower amount of binocular summation of the visual acuity while wearing the non-prismatic spectacle correction. Vice versa, participants with healthy eyes reached higher levels of binocular summation with the non-prismatic correction than with prismatic glasses and higher than the group of patients with macular diseases. We found similar trends after evaluation of subjective notions to the worn glasses of participants in both groups. Conclusion: The results of our study predicate that the non-prismatic correction is less effective than the prismatic binocular correction in patients with central retinal impairment considering the visual acuity gain. Nevertheless, it should not be considered as a rule. Instead of global management of the eyesight correction of patients with macular diseases with either prismatic or non-prismatic glasses, the approach should be individualized. Unambiguously, it would be a mistake to reject the possibility to assess the correction binocularly and apply it particularly in patients with central retinal impairment.

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