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TREATMENT OF GLAUCOMA
Currently the treatment aims to optimize, that is lower, a given patient's eye pressure. Often the initial reduction targeted is 25-30% from baseline. It is important to remember that the eye pressure can vary during the day, and the time of day has to be taken into account with each measurement.
Further, the blood supply should be optimized by maximizing the control of both diabetes and hypertension, considering the use of Aspirin every other day and minimizing low blood pressure at night, for instance, by taking a blood pressure pill in the morning rather than the evening.
Currently, there are no treatments to alter the genetic make-up of patients with glaucoma and no approved treatments to neutralize the toxic spillover from dead cells.
Most importantly, the goal is to prevent further damage.
Prevention includes performing laser surgery in those at risk of acute glaucoma prior to its occurrence. Usually, such patients will not require any further treatments.
The lowering of the eye pressure can be achieved with drugs - usually eye drops - laser or surgery. By and large, the preferred first choice is medications.
Over the last 5 years, a number of new medications has become available and the treatment of glaucoma has greatly improved.
For the longest time, the only drops available were called miotics, such as a drug by the name of Pilocarpine. They make the pupil smaller, darken the vision, increase nearsightedness and cause a headache. They also often require administration four times per day. However, when tolerated they are quite effective.
For the last 20 years, the former have been largely replaced as first-choice by drugs called beta-blockers like Timoptic (timolol maleate), Betagan (levobunolol) and Betoptic S (betaxolol). They only require administration once or twice a day. They can, however, have systemic side effects such as aggravating a tendency to suffer asthma attacks, disturbing heart rhythm, and possibly aggravating tendencies towards impotence and depression.
Often it is necessary to take more than one kind of medication. Hence the introduction of Timpilo 2 and 4, a fixed combination of two of the previous medications requiring use only twice a day, was a great improvement.
More recent addition have been Trusopt (dorzolamide) and Azopt (brinzolamide) which have largely, though not totally, replaced a tablet called Diamox (acetazolamide). The latter has many systemic effects, from numbness and tingling, weight loss, and kidney stones to anemia. Those systemic effects are extremely rare with the drops, although there is a fair incidence of local allergies which can lead to very itchy eyes and extremely red and swollen eyelids. Very recently timolol and dorzolamide have been combined in Cosopt, again for twice daily administration.
Another class of medications are called alpha-agonists and include Propine (dipivefrin), Iopidine (apraclonidine) and Alphagan (brominidine). Their side effects are mostly local. The first two have a rather high incidence of allergies and are rarely used on a long-term basis. Dipivefrin is combined with levobunolol in Probeta. They all are used twice a day.
The last category of new medications includes Xalatan (latanoprost). It is used only once a day. There are few side effects, except it may stimulate the growth of the eye lashes and cause the iris (the coloured part of the pupil) to darken permanently.
What one should always remember about medications is that they all potentially have side effects, don't work in everybody, often don't work forever, and only work when taken. A medication prescribed but not used regularly does little good.
Any patient taking glaucoma medications and developing an itchy, red eye with a swollen eyelid probably has an allergy to one of the drops, rather than an infection.
Laser treatments for glaucoma fall into three categories. Firstly, there is the iridotomy, a laser to prevent or treat acute glaucoma. It creates a small opening in the iris - the coloured part of the pupil. Once big enough, it does not need to be repeated. Rarely patients complain after the treatment of noticing a "white line" in their lower field of vision. This sensation usually subsides with time and can be remedied should it persist.
Secondly, a laser trabeculoplasty treats the drainage network of the eye to effect an increase in the fluid leaving the eye. It does not make any actual holes, but seems to cause the drainage pores to open more widely. Its effect is not permanent, although it might persist for up to 7 years. The immediate side effects are minimal, but there is still debate whether or not it might increase the failure rate of future surgery.
Thirdly and rarely, lasers are used in the process of surgery or in the ultimate destruction of the fluid-producing area once everything else has failed. This has not proven as successful as initially hoped, and remains by and large a method of last resort.
Surgery mostly involves creating a new passage for the fluid to leave the eye. The most common operation is called a trabeculectomy. A small trap door is created in the wall of the eye, usually under the upper lid. The fluid then drains into the space between the white wall of the eye and the clearer surface covering. Often a little blister forms beneath the upper lid. The body has a natural tendency to close that space. The use of medications to inhibit this body response has greatly improved the success rate of the surgery. The two most commonly used medications are 5-Fluorouracil and Mitomycin. They both inhibit the division of cells and slow down the healing process. Of course, at times and certainly when used excessively, this can be a bad thing. The healing process after the operation and its management are as important as the operation itself.
The operation can be combined with cataract surgery.
An alternative operation, especially as a second or third operation is the placement of a drainage tube connected to a plate, which is secured to the outer wall of the eye. This is more involved, but can be very effective in certain situations.
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