Spectral filters in low-vision correction

Coloured filters are used to protect the lens, retina and other ocular tiss ues against the hazard of light damage and to improve the quality of vision mainly in cases of ocular media opacities. Four types of yellow, amber and orange filters have been designed as tinted glasses, shields and colour covering of spectacles. They were tested on 15 adult patients with partial cataract and on 80 children with congenital pa thology (i.e, macular hypoplasia, albinism, aphakia after congenital catara ct). The majority of the children had nystagmus, The filters with particula r spectral characteristics provide reduction of light intensity in the ligh t-damaging range by at least a factor of five. Optimal filters were selecte d by examination of visual acuity, contrast frequency sensitivity, glare se nsitivity and subjective selection by the patients. The effects of filters were: 11-43% increase in corrected visual acuity, 27-34% increase in contra st sensitivity function (CSF) for ail frequencies and a marked reduction in glare sensitivity, All patients reported subjective improvement including reduction of photophobia, eye-strain and eye discomfort. It is concluded th at coloured filters are able to contribute substantially to rehabilitation of low-vision patients. (C) 2000 The College of Optometrists, Published by Elsevier Science Ltd. All rights reserved.