Common Mistakes Using Eyedrops
Chat Highlights
April 5, 2006

On Wednesday, April 5, 2006, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Common Mistakes Using Eyedrops."

Moderator:  Good evening, Dr. Wilson.  The topic tonight is "Common Mistakes Patients Make With Glaucoma Medications."

P:  Dr. Wilson, what's the most common mistake patients make?

Dr. Rick Wilson:  Missing eyedrops, especially those that are supposed to be taken two or three times a day.  Eyedrops are prescribed every eight to twelve hours, because that is how long they remain effective. If the patient doesn't take them on schedule, the IOP (intraocular pressure) increases, sometimes markedly.  Swings in IOP are increasingly becoming recognized as a risk factor for glaucoma progression.  Therefore, taking eyedrops two times a day should be as close to every twelve hours as possible, and three times a day as close to eight hours as possible.

P:   How big is a "swing" of four mm Hg in IOP?

Dr. Rick Wilson:   A normal daily variation is about four mm Hg, so much above that puts the patient into no-man's land.

P:   What is "no-man's land"?

Dr. Rick Wilson:   That's an area about which we are just learning.  Is a five mm Hg variation harmful in someone who already has nerve damage?  We don't know for sure.

P:   If more than one drop is needed, how long should we wait to put in the second drop?

Dr. Rick Wilson:   Ten minutes, so the second drop does not wash out the first.  Three drops can be put in the eye in 20 minutes.

P:   It is almost impossible for a patient taking four different kinds of drops to wait ten minutes between drops.

Dr. Rick Wilson:   Most patients who are taking that many drops take Cosopt, which is a combination of Trusopt and Timoptic.  Therefore, four different medications can be taken in three drops at night and two in the morning.  More than three medications is unlikely to help much, and anything over four is rarely effective.

P:   What if the patient goes to bed at 8:00 p.m., sleeps 12 hours, and needs to use an eyedrop three times a day?

Dr. Rick Wilson:   That patient's doctor will have to adjust the kind of medications being used, so that only eyedrops that need to be taken two times a day in that medical combination are used.  I rarely prescribe three-times-a-day eyedrops, since there is nothing in the mid-afternoon to remind the patient to take the medication.  The medication usually ends up being used two times a day, but at the wrong hours.

P:   Why is there a difference in opinion among doctors about the timing between drops and how the drops should be administered?

Dr. Rick Wilson:   Perhaps that's due to a lack of knowledge or how to present the information to the patient. In all honesty, you need to wait only five minutes between drops to prevent the second drop from washing out the first.  However, if I tell my patients to wait five minutes, they wait two or three.  If I tell them to wait 10 minutes, they wait five.

P:   Do you find that instilling drops can cause problems for some patients?

Dr. Rick Wilson:   Yes, especially those with arthritis, a tremor, and those who are far-sighted and cannot look in a mirror to help get the eyedrop in the eye.

P:   Do I need to be concerned about giving myself too small or too large an eyedrop?

Dr. Rick Wilson:   Yes and no. Some of the droppers put out too large a drop. Medications like beta-blockers and Alphagan can have side effects, so a minimally effective drop should be used.  On the other hand, most drops are in the range of 35 to 55 microliters and the eyelids will only hold 15 microliters.  Anything over that amount runs down the nasolacrimal duct into the nose or spills out and runs down the face.  With each blink, tears from the eye and medication, if it is in the tears, is pulsed down the nasolacrimal duct, which is located at the nasal end of each eyelid just before it reaches the nose.  The duct goes into the nose.  That is why you taste the salty tears after you cry.

P:   What is punctal occlusion and why is it done?

Dr. Rick Wilson:   Blocking the duct by covering the puncta for three minutes prevents most of the drop that has been instilled into the eye from reaching the nose, where it is efficiently absorbed by the nasal mucosa.  By keeping the medication longer in the tear film covering the cornea, more is absorbed into the eye, where it can work.  That is why we instruct some patients to use punctal occlusion.

P:   Do you think there's a significant difference in efficacy between using punctal occlusion and passive lid closure?

Dr. Rick Wilson:   Since it is the blinking action of the lids that provides the pump that powers the tears and medication into the nasolacrimal duct, just gently closing the eyes for three minutes does almost the same thing as punctal occlusion.

P:   Why do pharmaceutical companies make the size of the eyedrops larger than necessary?

Dr. Rick Wilson:   I think they are working to improve that. Some years back, Merck introduced the Ocumeter, which delivered a 35 microliter drop, 20 microliters smaller than most at that time.  Alcon has recently introduced the Travatan Dosing Aid to make taking Travatan easier, to remind the patient to take their drops, and to monitor compliance for the doctor.  Pfizer has developed an airless antibacterial dispensing system (AADS) that mists a set dose of medication onto the eye, while preventing contamination of residual medication, which eliminates the need for a preservative.

P:   I think the plastic in the Alphagan P bottle has been changed. I now have to squeeze it to get the drops out. What's more, the last two months I have run out of the drops almost a week early.  My pharmacy actually told me to skip a dose, which I'm not supposed to do.

P:   My sister had a problem with running out of Alphagan P, because the bottles contained only 5 microliters instead of 10.  The bottles are the same size. Have you heard of that, Dr. Wilson?

Dr. Rick Wilson:   Unfortunately, yes.

P:   Some glaucoma patients say their eye doctors are prescribing memantine (Namenda) for them.  To my knowledge, the results of the memantine study have not been published.  Will you please comment?

Dr. Rick Wilson:   The results of that study have not been published. However, for desperate patients, desperate doctors may prescribe memantine.

P:   Have you treated any nursing mothers?  If so, were they able to take their drops and continue to breastfeed?

Dr. Rick Wilson:   That is a difficult problem, as some medications are passed through the breast milk to the baby.  A mild dose of beta-blocker once a day or Trusopt or Azopt should be tolerated by the baby.  I use those two in congenital glaucomas.

P:   My doctor wants to start drops in just one eye.  Why is that?

Dr. Rick Wilson:   That is known as a therapeutic trial.  Since eye pressures go up and down throughout the day, if a medicine is prescribed in both eyes and the IOP is down on the next visit, the doctor doesn't know if it is due to the medicine or the time of day.  If it is prescribed in one eye only, the IOP should be lower in the eye being treated, demonstrating effectiveness.

P:   Why don't "glaucoma suspects," that is, patients with ocular hypertension, receive treatment until there is evidence of nerve damage?

Dr. Rick Wilson:   There are probably nine patients with elevated IOP who are not demonstrating damage for every one who is.  Therefore, we do treat ocular hypertensives, but only those with seriously elevated IOP or several risk factors for damage.

P:   Do you see angle-closure attacks because people ignore glaucoma warning labels on over-the-counter medications?

Dr. Rick Wilson:   Patients who know they have narrow angles have usually had a laser treatment, or are on medication, or both.  Those who don't know they have narrow angles are the ones the labels are meant to help, but obviously can't.

P:   Can you explain more about the warnings for allergy medications and what ingredients in them can cause problems?

Dr. Rick Wilson:   Medications like pseudophedrine cause mild dilation of the pupil, which puts people with narrow angles at risk for an angle-closure attack.

P:   Are those allergy meds okay to take with open-angle glaucoma?

Dr. Rick Wilson:   Yes.

P:   Are any of the prostaglandin analogs available without preservatives?

Dr. Rick Wilson:   Not yet.  I have a huge day tomorrow so will hit the sack. It was great to see all of you here tonight.

Moderator:  Thank you, Dr. Wilson. As always, your time and answers are appreciated.

On April 12, Dr. Wilson discussed "Glaucoma and Visual Function" in the Chat room. Click here for highlights of that meeting.

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