GLAUCOMA TREATMENT

WHAT IS GLAUCOMA?

Glaucoma is damage to the optic nerve — the “data cable” that connects the retina to the brain. The optic nerve passes through an opening in the back of the eye that has a waterproof membrane to prevent eye fluid from mixing with brain fluid. But if the eye pressure is too much higher than the brain pressure, the optic nerve will be pushed backwards and damaged by displacement and compression. A thick-walled eye can better resist a pressure imbalance; near-sighted people have stretched out eyeballs with thin walls, which are more easily damaged, even if the eye pressure is just in the high teens. Slender people have lower brain pressure, which also increases risk. And low blood pressure, from overtreatment or just being slender, increases risk because compressed nerve tissue has kinked blood vessels which need more pressure to maintain flow.

Lowering eye pressure is the main treatment. In patients with advanced glaucoma, blood pressure treatment should not lower BP to less than about 130/75 unless there is significant cardiovascular disease. Very slender glaucoma patients would do well to gain some weight, but I rarely see skinny glaucoma patients gain a significant amount of weight. Encouraging young children to play outside and avoid excessive near work (reading, video devices) helps avoid myopia; if a child is developing myopia, atropine drops and special glasses with peripheral defocus should be considered to slow the process.

Target pressure: keeping the intraocular pressure in the mid teens is the key to glaucoma treatment: if the nerve damage is minimal, 18 may be sufficient; if the damage is severe, 13 is better.

There are 2 drains for the internal fluid of the eye (aqueous humor, which is completely separate from the external tears ). The front drain (trabecular outflow) carries most of the fluid: its function is enhanced best by the SLT laser which is proven safe and more effective than medication. The back drain (uveoscleral outflow) is boosted by prostaglandin medications like latanoprost.

The ciliary body manufactures the fluid, pumping aqueous humor into the eye. Medications like timolol, dorzolamide and brimonidine slow down aqueous humor production.

As you might imagine, it is usually very effective to simultaneously enhance the front drain by SLT laser and back drain by latanoprost while slowing the fluid production with timolol/dorzolamide.

In open angle glaucoma, the fluid can reach the front drain, but the pipe system is clogged like a slow sink drain clogged by hair and grease. SLT laser (selective laser trabeculoplasty) works well for this. It heats up the trabecular meshwork (but does not burn, scar or cut the tissue) which stimulates the immune system to send special white blood cells (macrophages and monocytes) to the drain. The immune cells digest debris and release special chemicals (interleukins) that improve the drain. The immune response wanes over time, so it is often helpful to repeat the laser about 5 years later (sometimes sooner).

Less commonly, the iris blocks the front drain opening like a drainplug in a sink, and the glaucoma is classified as angle closure. Laser iridotomy can usually prevent angle closure from developing. In established cases, cataract removal helps get the iris out of the drain opening because the replacement artificial lens implant is much slimmer than the natural lens — this creates extra space in the eye so the iris can move away from the drain opening (trabecular meshwork).

LIFESTYLE FACTORS

Unlike high blood pressure or cholesterol, glaucoma cannot be managed by diet and exercise alone. However, there is plenty of evidence that a healthy lifestyle makes glaucoma less likely and easier to manage.

• Get a few hours of exercise each week.

• Drinking 4 or more cups of coffee a day is bad for glaucoma.

• Lots of alcohol is definitely bad for glaucoma, and none may be best. But I think one drink per day is reasonable considering enjoyment and social factors.

• Cigarette smoking and vaping are definitely bad for glaucoma. I have seen several heavy smoking patients with severe glaucoma lose their vision even though the eye pressure was successfully lowered.

• CBD can raise the eye pressure. (CBD is a molecule in cannabis plants that does not make you high, but is sold for pain and sleep. THC, the part of cannabis that makes you high, does lower eye pressure, but only for a few hours. I agree with the vast majority of glaucoma doctors that cannabis is of little use for treating most glaucoma patients.)

• Eat about 6 fruits and vegetables each day (2 with each meal); avoid processed foods; eat whole grains and fish; limit dairy and meat that was not raised in the wild. One soda per day is enough to ruin your health.

• Don’t worry about weight lifting and upside down yoga positions even though you will read that they can temporarily raise the eye pressure: the sources cautioning against weight lifting and inverted postures are not considering that those activities simultaneously raise the brain pressure as well as the eye pressure, so the pressure balance across the optic nerve is likely not much stressed. No studies show glaucoma to be more common among weight lifters and yoga practitioners, nor have I ever observed that in my patients. Nevertheless, I would avoid breath holding during weight lifting and avoid hand/head stands longer than 30 seconds.