Clinical Glaucoma Research

Of the several projects we are conducting with the financial support of the American Health Assistance Foundation, I would like to highlight three recent findings. The first has to do with modern automated (computerized) visual field testing. These new methods represent an advance both in administering the test and in analyzing the test results. This allows more accurate diagnosis of glaucoma, as well as more accurate determination of whether the vision of a patient with glaucoma is or is not deteriorating. However, the methods are new. Patients, technicians, and ophthalmologists alike must adapt to the new testing methods and its interpretation. Some patients find the new method of field testing is more difficult for them, requiring more concentration. However, the future promises to hold simplification and shortening of the test to make it more acceptable. Meanwhile, we are learning to make more reliable interpretation of the results of automated visual field testing. This last year we realized that the computer sometimes labels a test unreliable when in fact the patient had done a good job and the test was actually quite reliable. We conducted an experiment to show that technicians could recognize the testing flaw that makes the computer falsely label the field test as unreliable. The technician can intervene in the testing procedure and correct the problem, so that a more accurate distinction is made between reliable and unreliable visual field testing. The results of this study will soon be published in one of the scientific journals so that ophthalmologists everywhere can use this technique in their office and thereby take one additional step toward improving the quality of diagnosis and care of patients with glaucoma. The second area in which a research advance has been made has to do with an ocular condition called “nanophthalmos”. Patients with nanophthalmos have small far-sighted eyes in which the outer coat (sclera) is unusually thick. They develop one of the forms of secondary angle closure glaucoma (there are more than 30 types of glaucoma, all told). As patients with nanophthalmos get older, they can also develop cataracts, as do many older individuals, whether they have glaucoma or not. The glaucoma associated with nanophthalmos is often difficult to control with medications alone, and surgery is often required. The problem in years past is that when cataract or glaucoma surgery is performed on an eye with nanophthalmos, a terrible “uveal effusion” occurs, sometimes leading to retinal detachment and other ocular disturbances that can make the eye go blind. Thus when a patient with nanophthalmos has severe cataract or uncontrolled glaucoma, the ophthalmologist is in a terrible dilemma because the surgery, while potentially of benefit, also has a high risk. In the last decade laser treatments have become available as an alternative, and we also developed a surgical method to avoid or treat the complications that occur following cataract and glaucoma surgery. This year we reviewed the last decade of our experience with these new techniques and were able to report in the scientific literature that these new methods are indeed far safer than methods in use previously. It is now safe to consider surgery in nanophthalmic eyes that are threatened with cataract and glaucoma. It is no longer necessary to be quite so fearful of surgery in these cases, and hence surgery can be undertaken at an earlier stage before it is in fact too late to save the vision in the eye. We know that quite a number of patients with this condition are now receiving the benefit of the new methods, as ophthalmologists with patients who have nanophthalmos have called us to clarify the details of the methods they can use for their patients. It should be mentioned that this type of glaucoma due to nanophthalmos is exceedingly rare. Most other cases of glaucoma are controlled well without surgery. Even if they do need surgery, it is safe, without the risks that are present with nanophthalmos. The new methods are an improvement in surgery specifically for those patients who do have nanophthalmos, and we hope our report on these new methods will avoid the disastrous results that can occur in those cases. In a third area of research, we were able this year to confirm a new theory (developed at Duke University) on the underlying abnormal physiology that occurs in eyes with narrow angles or angle closure glaucoma. Although the theory appeared sound when it was developed several years ago, the researcher at Duke University did not want to announce the new theory until it had been proven to be true by actual measurements in patients who had this type of angle closure glaucoma. We had developed a method for measuring very accurately the position of every point on the iris inside the living eye, and we used this method to demonstrate the validity of the new theory. Both a description of the theory and our results confirming it will appear in the scientific literature very soon. The findings do not yet translate into a change in treating angle closure glaucoma. However the theory is fundamentally different from anything previously described, and it should provide a basis for studying all cases of angle closure glaucoma and learning how to recognize several different types, each of which might require somewhat different treatment. It is the generosity of those who donate to National Glaucoma Research that has allowed us to come this far, and we hope that continued support will allow us to make further, clinically meaningful advances.

2nd Year

In most forms of glaucoma, the intraocular pressure is higher than normal. The high pressure, along with other pathologic factors, damages the optic nerve, so that vision is lost over a period of time. In one type of glaucoma, called “normal tension glaucoma” (sometimes also called “low tension glaucoma”), the pressure is in the normal range, but the optic nerve suffers damage and vision is lost anyway. It is not known exactly why this happens, and for this reason it is also not known how much benefit is derived, if any at all, from lowering the intraocular pressure from a normal value of 17 mm Hg down to the range of 10-12 mm Hg, for example. Along with many other centers, we are randomly leaving some eyes with this condition alone while others are treated aggressively to achieve at least 30% lowering of pressure. Then, over the next several years, information is collected about whether or not the nerve suffers further damage and there is further slight visual loss, and at what rate any visual loss might be occurring, along with information about undesirable side-effects from the aggressive treatment. After several years we hope to know better how cases of this type should be treated. We are also doing a series of studies to make accuracy of visual field testing better. One problem, for example, is that people who have glaucoma are in an age group that they often also develop cataracts. If their vision deteriorates a little bit over a period of a couple of years, it is sometimes hard to tell if the cause is worsening of glaucoma or slight worsening of cataract. For that reason we are studying the effects of simulated cataract on visual fields by holding calibrated pieces of ground glass in front of the eye as the visual field is tested. We had previously done this for people with normal visual fields, and we are now testing this on people who have glaucomatous visual field defects. We hope in this way to make the diagnostic accuracy of visual field testing better. We are also studying a new concept in screening visual fields to see if there is any abnormality present, and what type, in a manner that will hopefully be sufficiently accurate while at the same time much faster.