To determine the most common causes of blindness and the age of onset of these conditions among Jordanians of Irbid, a study of all registered members in two societies for the care of the blind was carried out. Of all registered members, 185 individuals were blind according to the World Health Organization definition and satisfied our inclusion criteria. It was found that genetically determined causes made up 41% of the total causes. In 57% of the subjects, blindness occurred in the first two decades of life. The specific leading causes of blindness, in the order of their frequencies, were tapetoretinal degenerations as different variants of retinitis pigmentosa (17.6%), glaucomas (16%), diabetic retinopathy (13%), post-infection corneal scarring (11.5%), congenital cataract (8.8%) and uveitis (8%). The results reflect the satisfactory achievements in primary health care levels and the challenge to make specialized tertiary health care more accessible.
Focal retinal pathology and dysfunction as a sequel to manifest damage due to operating microscope illumination is well recognised. We wished to determine whether retinal dysfunction could be identified in the absence of clinically visible lesions. We therefore have conducted a prospective controlled study on 36 patients undergoing cataract surgery and 27 control subjects. A Wild M690 zoom operating microscope was used for each procedure. No filters were used. The Humphrey visual field equipment was employed to determine threshold retinal sensitivity at predetermined loci above and below fixation in both groups. No clinically visible retinal lesions were seen in any patient. However, post-operative investigation revealed a statistically significant depression in retinal sensitivity at points most exposed to operating microscope illumination (p < 0.05). This was most noticeable following longer total operating times and in patients with the longest time intervals between lens extraction and completion of the procedure. It is concluded that operating microscope position and centration, and the position of the eye, should be adjusted to place the image of the illuminating element away from the foveola. Also retinal illumination should be kept to a minimum, particularly after an intraocular lens has been implanted.
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