Clinical Glaucoma Research

Through the years, the grant from National Glaucoma Research has permitted us to work in a number of areas relating to glaucoma. Each area has its own separate specific aims and long term goals. We have conducted a number of studies relating to the testing of the visual field as a diagnostic procedure in recognizing glaucoma and in following the adequacy of its treatment. We have within the last year published a paper demonstrating how glaucoma can be recognized in a very early stage in some cases by comparing the overall visual sensitivity in one eye with the visual sensitivity in the other eye–a method that has not before been used for the diagnosis of glaucoma. We have also published a paper in which we determined the conversion factors between the several types of perimeters now used in ophthalmologist’s offices across the country. Without such conversion factors, it is impossible to compare the visual field examination results on two occasions when the examination was performed on two different instruments. Another aspect of interpretation of visual field examination results is to distinguish between the effects of cataract on visual fields and the effect of glaucoma. Over several years we had performed a series of studies in which we imitated cataracts with various types of light filters. The results were described in a series of scientific publications, the most recent of which has been accepted for publication by the American Journal of Ophthalmology and will probably be published before the end of this calendar year. Our ongoing work on visual fields will also relate to cataract, representing the practical application of the previous work. We are actually measuring the degree of cataract in a patient before he undergoes surgery and performing a visual field examination on him before and after he has the cataract removed in order to determine what effect the cataract had on the visual field. There are cases of glaucoma in which the intraocular pressure is not very elevated, or may actually be completely within the normal range. These cases are called either “low tension glaucoma” or “normal tension glaucoma”. In 1988 we published a paper describing how the glaucoma was typically worse in the eye with slightly greater pressure, indicating that the level of pressure is important even when it is within the normal range. There was an exchange of correspondence concerning that topic published in the literature in February 1989, and later in the year our article was translated for publication in the Chinese edition of the Archives of Ophthalmology. Our main work on normal tension glaucoma, however, is as a participant in a multi-center randomized clinical trial. It is not quite certain how much it helps to lower the intraocular pressure drastically in these cases. In particular we want to know who much benefit is derived and compare it to the frequency and severity of side-effects from aggressive treatment. Such a study is necessarily long-term, as one has to see what the results are over several years before coming to a conclusion. As the information accumulates, it is reviewed by a Data and Safety Monitoring Committee, whose job it is to make sure that nothing harmful is being done and to determine when there is enough information to know whether aggressive treatment is better or not. A third area of study concerns angle closure glaucoma . Last year we published a scientific paper describing the technical details of analyzing the geometry of the front part of the eye in relation to angle closure glaucoma. This year we have been using that method to begin studying angle closure glaucoma in a new way. We have concentrated first on normal individuals of various ages and racial background (for example, Asians are known to have a tendency for angle closure glaucoma, and we were able to get quite a number of Chinese people to have special photographs of their eyes taken so that we could make measurements). The process of making the geometric measurements is time consuming, but we hope to have some initial results ready to prepare a scientific report in 1990.