Eye Didn't Know!

Using Eyedrops

Did you know? Patients are routinely prescribed eyedrops for a variety of conditions, including dry eye, infections, glaucoma, and for post-operative care. Few patients, however, are given instructions on how to instill their eyedrops. When asked to demonstrate how they instill their drops, few patients are able to perform drop administration reliably, which means that they may be receiving inadequate medicine, or may be spending too much on drops because the drops don't enter the eye on first attempt.

The sketch below shows proper technique. One stands in front of the mirror, pulls the lower lid down, and places one drop into the pocket formed. The drop does not need to be placed on the eyeball, and one drop is all that is necessary.

That's all there is to it!

(image courtesy of American Academy of Ophthalmology)

Did you also know? Closing the eyes gently for a minute or two after drop instillation may help increase its absorption into the eyes and keeping the medication out of the bloodstream.

Glaucoma: a family affair?

Did you know? Ophthalmologists routinely inquire about a family history of glaucoma, as it has long been known that glaucoma can run in families (the exact genetics are not known for most glaucomas, though). A recent study published in the British Journal of Ophthalmology compared the eye pressures of identical twins and non-identical twins. (Twin studies are a classic way of determining the role of genetics vs. environment). The study determined that genetics explained approximately 2/3 of the variability of eye pressure, while environmental factors explained approximately 1/3. This is a remarkable finding. Choose your parents well!

Did you also know? If you have a family history of vision loss from glaucoma, this study provides more reason to see an ophthalmologist at regular intervals, and remind your ophthalmologist of your family history.

(photo: twin girls: wikimedia commons)

Happy Birthday, Jose Feliciano

Did you know? Puerto Rican-born singer Jose Feliciano was born blind from congenital glaucoma. Congenital glaucoma is a rare condition where the drainage system of the eye does not function properly, leading to high pressure in the eye and damage to the optic nerve. When this occurs around birth, the eyes sometimes enlarge leading to an unusual appearance. Even with modern treatment, usually involving surgery and medications, the prognosis for this condition is guarded.

Did you also know? In 1967, Jose Feliciano traveled to England for a concert tour. Authorities would not allow his guide dog into the country (due to rabies laws). Later, he wrote the song, No Dogs Allowed.

Glaucoma Linked to Low Pressure in Brain?

Did you know? A study published in the May 2008 journal Ophthalmology found a fascinating link, which, if verified, could alter how we think of glaucoma. The Mayo Clinic studied the records of all patients who had lumbar punctures (spinal taps) between 1996 and 2007. They identified 28 of these patients as having glaucoma, and compared them to 49 patients who did not.

During a lumbar puncture, the pressure within the spinal column (which connects to the brain) is measured. The spinal pressure in the glaucoma patients averaged 9 mm Hg, and the controls measured 13 mm Hg. Since the average eye pressure is between 10 and 21, (often higher in glaucoma) that means that the pressure gradient between the eye and the brain could be higher in the glaucoma patients. This would damage the optic nerve, which is seen in glaucoma.

Did you also know? The only accepted treatment we have now for glaucoma involves lowering eye pressure, with eyedrops, laser, or surgery.

Are we due for a new class of glaucoma medications?

Did you know? It has been twelve years since there have been any significant additions to our supply of medications for glaucoma. In 1996 Xalatan was introduced, the first of the prostaglandin agents which quickly took over first-line therapy for most glaucoma patients. The prostaglandins simply worked better with fewer side effects than the other medications available.

A new class of medication may be on the horizon. Rho-kinase inhibitors, (ROCK-inhibitors) are molecules which relax smooth muscle, a muscle which is found, among other places, in the drainage system within the eye.

When this drain does not work properly, the pressure within the eye rises, which can lead to damage to the optic nerve within the eye. When this happens, vision can be lost, and we call it glaucoma. Relaxing the mesh-like tissue within this drain can apparently cause pressure to be lowered.

Several pharmaceutical companies are looking into these molecules. Studies in monkeys have shown a larger pressure lowering effect than Xalatan!

Will these studies result in a new class of glaucoma medications? Only time will tell. Ophthalmologists and glaucoma patients could benefit from a new arrow in our quiver!

More information can be found here.

Did you also know? Statin drugs (lipid-lowering agents) such as Lipitor, Zocor and Crestor are also ROCK-inhibitors.

Measuring Eye Pressure

Did you know? Until 1905 there was no objective way to measure pressure within the eye. In that year, Norwegian ophthalmologist Hjalmar Schiotz invented the first tonometer, which now bears his name, the Schiotz tonometer.

Until this time, doctors estimated pressure within the eye by pushing on the eye through the eyelid, and guessing, much like you might push on a bicycle tire with your thumb and guess the pressure. The Schiotz tonometer actually works in much the same way, it measures the weight necessary to indent the cornea a standard amount.

Knowing the pressure more accurately allows us to better diagnose and treat glaucoma, a disease usually caused by elevated eye pressure damaging the optic nerve.

The Schiotz tonometer is still used in many parts of the world, and when I trained, it was what most doctors used as a portable tonometer.

Did you also know? Dr. Schiotz was also responsible for introducing the concept of sterilizing surgical instruments (by boiling) to Norway.

Steroid for Glaucoma?

Did you know? It may be possible to lower eye pressure in glaucoma with injections of a steroid called anecortave acetate. Although most steroids have to potential to raise eye pressure, this steroid has been shown in a number of studies to lower eye pressure. Researchers at Johns Hopkins, in Baltimore, injected a small amount of medicine or placebo just under the surface of the eye in 85 patients. After three months, the patients receiving the medicine had a pressure reduction of 7.4 mm Hg compared with 1.4 mm Hg in the placebo group. Read more here.

Did you also know? Many patients have enormous difficulty taking their glaucoma eyedrops properly. If it becomes possible to control eye pressure with a painless injection under the eye every three, six, or twelve months, that would give us a very important additional measure to preserve vision in glaucoma.

Alternative Therapies for Glaucoma?

Did you know? It is said that 50% of patients with glaucoma use "alternative" therapies, that is, therapies other than those prescribed by their physician. The rate may be higher in Asian populations. The question is, do they work??? A prominent glaucoma specialist from San Francisco, John Hetherington, M.D., recently reviewed the literature on the subject. He reached the following conclusions:

Vitamins A, B1, B12, C, and E, as well as antioxidant supplements, had no meaningful effect on intraocular pressure or glaucoma progression.

Marijuana decreases eye pressure, but its effects are very short–lived with significant side–effects. Topical application of its components (there are over 400!) has not yet shown to be effective, but is being studied.

Ginkgo biloba increases ocular blood flow and thus may protect the optic nerve. Dr. Robert Ritch is a specialist who has advocated gingko use for glaucoma for many years. Gingko may cause side effects such as bleeding, especially when used with aspirin, so should be used with caution or after consultation with a primary care physician.

There is no evidence that bilberry is beneficial for glaucoma or optic nerve health.

Drinking excess water can raise eye pressure temporarily.

Alcohol can decrease eye pressure temporarily, but obvious toxicity can result with excess!

Meditation produces insignificant reduction in eye pressure.

Acupuncture has not be shown to affect eye pressure.

Exercise has a significant eye pressure lowering effect over time.

In summary, exercise and possibly gingko are the only alternative therapies which currently may be effective in glaucoma. So save your money and keep walking!

Did you also know? Yoga exercises which feature inversion for long periods of time should definitely be avoided in glaucoma, as they can increase eye pressure greatly!

(photo by Joseph Renger, wikimedia commons)

You want to take my temperature where?

Did you know? A recent study published in the British Journal of Ophthalmology demonstrated that the temperature of the surface of the eye correlated with the blood flow in the back of the eye. It is believed that decreased blood flow to the optic nerve may be a risk factor for developing glaucoma, so a decreased surface temperature may indicate poor blood flow, which may be a risk factor for glaucoma.

Did you also know? In the past five years most ophthalmologists have routinely started to measure corneal thickness in glaucoma suspects, as thin corneas have been shown to increase one's risk for glaucoma. (we are not sure why!)

The ultimate eye pressure gauge

Did you know? Researchers in Germany say they have developed a sensor which can be integrated into an intraocular lens to continuously monitor the pressure within the eye.

Patients with glaucoma suffer damage to the optic nerve and possible vision loss when the pressure exceeds a safe level. The standard of care today is to check the eye pressure at the ophthalmologist's office, which might occur once every three, six, or twelve months. This obviously does not give a complete picture of the eye pressure within the eye.

Most patients with glaucoma eventually need cataract surgery. A lens implant containing a sensor to continuously monitor pressure, transmitting it to an external receiver, would provide us with a wealth of information.

This device is in trials and could be available within three years. Read more here.

Did you also know?
A similar device could be implanted in a major artery to continously monitor blood pressure!