[Age-related macula degeneration and diabetic retinopathy -- differences in optic rehabilitation]

Age-related macular degeneration (AMD) and diabetes mellitus are the major contributing causes of visual impairment in the industrial nations. This study shows how far visual acuity (VA) and magnification demand (MD) influence the selection of suitable low vision aids. Based on this information, differences regarding the spectrum of prescribed magnifying devices between both patient groups will be presented.

Between January 2003 and October 2004, a total of 2500 patients was seen in our Low Vision Department. Among them were 1198 patients with AMD (48 %) and 296 visually impaired patients because of diabetic ocular involvement (12 %). In every patient, best corrected distance and near VA as well as the required MD were measured. Finally, matching of magnifying aids and discussing aspects of professional and social rehabilitation were the main parts of our interdisciplinary Low Vision Service.

In AMD patients, the average of best corrected distance VA at the better eye was 0.24, the best corrected near VA was 0.19. In diabetes patients, the average of best corrected distance VA at the better eye was 0.28, the best corrected near VA was 0.22. The required mean MD was 4.0 x (related to the reading of newspaper text) compared to 7.6 x in patients with AMD. In 94 % of the visually impaired diabetes patients, optical magnifiers could be prescribed (e. g. magnifying eyeglasses, telescopes, monoculars, Galelean and Keplerian systems), whereas electronic devices were necessary in only 6 %. In comparison, 14.8 % of the patients with AMD had to be provided with electronic systems.

In 94 % of the visually impaired patients caused by diabetes, reading ability could be restored using optical low vision aids. In AMD patients, this could be achieved in only 85.2 %. This fact can mainly be explained with the negative effect of absolute central scotomas on reading speed in AMD patients which leads, compared to diabetes patients, to elevated magnification factors. Therefore, the choice of certain magnifying devices depends not only on VA, but has mainly to be evaluated based on the individual MD.