A new low vision aid (LVA)-the Low Vision Enhancement System or LVES, which were as developed at the Johns Hopkins University in Baltimore, is now commercially available. This instrument allows a magnification up to 10 times with control of contrast and luminance while the field of view is very large: 60 x 40 degrees. We present first results concerning LVES in comparison to conventional LVAs.
Patients and methods: 60 consecutive patients suffering from macular dystrophy, macular degeneration, optic atrophy, tapetoretinal degeneration, or diabetic retinopathy were included in this study. We compared visual acuity with glasses, with telescope and using LVES. Furthermore we compared contrast acuity by the use of the Pelli-Robson-charts as well as the subjective impression of the patients.
Results: Improvement of visual acuity with LVES compared to correction with glasses was 8 log steps on average and up to 3 steps as compared to the use of telescopes. More important is the improvement of contrast sensitivity (0-16 steps) and the reduced glare. Despite the subjective improvement of visual acuity and contrast sensitivity the majority of patients could not imagine to use LVES regularly. A significant improvement as compared to conventional low vision aids is possible for special applications such as office work, recognition of faces or images or for looking at a blackboard.
Conclusion: In addition to traditional LVAs, the Low Vision Enhancement System opens up possibilities for a very small group of patients. Especially patients suffering from macular dystrophy or Lebers optic atrophy may benefit from this new system. The most important advantage of LVES is the improvement of contrast sensitivity and the significantly decreased glare sensitivity. Additionally the near working distance is changeable. The variable magnification allows an easier fitting to various tasks. Prior to the prescription of LVES a detailed and time consuming testing is necessary.