Science & Research

The black spots sound most characteristic of vitreous floaters. These floaters can be a result of vitreous gel breakdown, a process that occurs with aging. Vitreous gel is the clear jelly-like substance that fills the eye from the lens to the back of the eye. Floaters also can be a sign of a retinal tear or ocular inflammation. If you have new floaters and recent eye surgery, you should have a dilated retinal examination to rule out any retinal pathology.

Eye drops for glaucoma have different lengths of pressure-lowering effects based on their individual chemical properties. These differences dictate how frequently an eye drop needs to be administered to have its optimal effect, whether it is once a day or more frequently. When discontinuing eye drops, they have different "wash-out" times, and may take a few days to a few weeks to clear the system entirely.

The tonometer for home use is not as reliable as the gold standard Goldmann applanation tonometer. The eye pressures obtained with the home tonometer are not directly comparable to those obtained in the clinic, and thus may not necessarily be helpful for monitoring your glaucoma. Some glaucoma specialists do recommend this device for patient use in special situations. Your eye care provider can explain his or her recommendation for its use in your care.

Because I cannot see your brother's eye, I cannot be positive what the white ring is. However, I think you may be seeing a white ring that is actually on the cornea which is the clear part of the eye on top of the iris. This white ring is called arcus cornealis or arcus senilis. It often starts as an incomplete ring at the top and bottom of the cornea. In older adults and the elderly, it may progress to form a complete ring around the cornea. Arcus cornealis is caused by lipid or fat that is deposited in the cornea, but it is not necessarily related to high cholesterol levels. In fact, most individuals with high cholesterol do not end up getting arcus cornealis. In most individuals that do develop arcus cornealis, it is completely harmless and does not require any treatment. If it is present in younger adults, it may be related to extremely high cholesterol and triglyceride levels that are passed down genetically through families. We call this familial hyperlipidemia. If you are concerned about this ring or cholesterol levels, you should have an evaluation by an eye care specialist or your primary care doctor.

That is a great question, and one that many people ask. Unfortunately the answer is not as easy as telling you a single number. While the "average" eye pressure is approximately 15, the range of "normal" eye pressure is much larger. About 9 out of 10 people (about 90%) will fall somewhere between a pressure of 10 and 21. Even knowing this, it does not mean that if you have a pressure of 22 or higher it is "abnormal." Every individual and every eye is different. There are many patients with pressures in the mid-20s who do not have glaucoma and they can simply be followed with routine eye examinations by their eye care specialist. There are also patients who have been diagnosed with glaucoma and even though we get their pressure below 22, they still experience worsening of their glaucoma. If you are concerned about the pressure in your eyes, it is important that you see an eye care specialist so that they can do a thorough examination and determine if the pressure in your eyes are ok.

You state that the eye with good vision has no visual problems. I assume from this that it is the eye with worse vision and advanced glaucoma that has had the trabeculectomy and a pressure of 7. Progressive visual field loss in spite of pressures in the single digits is uncommon, but it can occur in an eye with extensive optic nerve damage. One possible explanation for this could be, if your cornea is abnormally thin, that the true pressure in the eye is actually higher than readings your doctor gets with the tonometer, which would be calibrated for a normal, thicker cornea. Corneal thickness can be easily measured in the clinic. It is also possible that, in an eye with advanced visual field loss, the optic nerve head damage itself makes the remaining nerve fibers increasingly susceptible to even lower than normal eye pressure.

Careful control of pressure in your good eye to prevent the development of glaucomatous damage should go a long way to keeping this eye from suffering the same problems of your bad eye. The reasons why increased pressure susceptibility occurs with severe nerve damage are poorly understood, and this is a very active and extremely important area of basic research. This work benefits greatly from support from individuals, such as yourself, donating to foundations like the American Health Assistance Foundation. Understanding these causes is likely to lead to new ways of protecting the optic nerve in glaucoma that can be used along with our traditional pressure-lowering therapies.

It sounds as if you have a condition known as normal-tension, or low-tension glaucoma. For many years, this was considered to be different (or due to a different underlying cause) than open-angle glaucoma, which is the most common form of glaucoma in the United States. However, there is increasing evidence that many cases represent a situation where the optic nerve head (the site of injury) is unusually susceptible to even normal eye pressure. Clinical studies have shown that lowering eye pressure can slow or stop the progression of visual field loss in many patients with normal-tension glaucoma. While unclear, it is possible that this susceptibility is related to the anatomic structure of the optic nerve head in that the tissues supporting the optic nerve fibers are either weak or too thin. As to the level of your eye pressure, it is possible that you have very thin corneas, and this is causing the tonometer (the instrument used to measure eye pressure) to underestimate the true pressure. If this is the case, then continued aggressive control of eye pressure is very important. There is still the possibility that there may be poor blood flow to the eye in some individuals, as this type of glaucoma has been associated with vasospasm and other consequences of this, such as migraine headaches. In some patients, blood pressure medications have been shown to contribute to this situation. If you are on such medications, then it is reasonable to review them with your glaucoma doctor as well as your primary care physician, in case it’s possible to reduce or modify these. This would be particularly appropriate if it is clear that your eye pressure is as low as it can be.

As to your prognosis, if your eye drops are keeping your pressure around 10 or so, and your visual function as determined by visual field testing is stable, then it’s not likely that you will go totally blind. If, on the other hand there is deterioration in your visual fields, or if your eye drops stop controlling your pressure adequately, consideration can still be given to filtering surgery (trabeculectomy), which can lower the pressure into the single digits. This would really depend on just what level of pressure you actually have.

A person that has been diagnosed with glaucoma often has a combination of several possible findings on their eye examination. These can include the pressure in the eye being too high, the optic nerve having changes characteristic of glaucoma, loss of some vision or visual field (usually on the outside or periphery), or other findings. A glaucoma suspect is someone who may have some suspicious findings on the examination, but does not have enough changes to make a definitive diagnosis of glaucoma. Sometimes these individuals have a strong family history or risk factors for glaucoma that makes the eye doctor want to follow that patient very closely even though they do not diagnose them with glaucoma. If you have been diagnosed with glaucoma or have been diagnosed as a glaucoma suspect, it is important to have regularly scheduled visits with your eye doctor so that they can make an appropriate treatment or observation plan.