Refracting Glaucoma Patients
Chat Highlights
May 8, 2002

Norma Devine, Editor

On Wednesday, May 8, 2002, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Refracting Glaucoma Patients."

Moderator:  Good evening Dr. Wilson.  Our topic tonight is "Refracting Glaucoma Patients." 

Dr. Rick Wilson:  Hello, gang.  

P:  Dr. Rick, what does "refracting" mean?

Dr. Rick Wilson:  It means checking how the light is focused (refracted) in reaching the retina. In a myopic, or larger-than-normal, eye, light is focused before it reaches the retina.  With lenses, the light can be focused further back, to hit the retina.  Hyperopia, or far-sightedness, is just the opposite of myopia.  By placing different lenses in front of the eye, we can choose the correct lenses for a particular patient.

P:  How well can you refract an eye with a rippled retina?  

Dr. Rick Wilson:  Since a rippled retina has some of the retina anterior to (in front of) the rest of the retina, and not pointed in the right direction, we have to achieve the best compromise of focusing the light on the retina.

P:  I don't understand that answer.

Dr. Rick Wilson:  A wrinkle in the retina causes distortion in the vision due to the problems I mentioned.  In a wrinkled retina, some of the retina is not pointed straight ahead, making it difficult to see well.  

P:  Does that mean you can't really refract a retina that has ripples?  

Dr. Rick Wilson:  Not perfectly, but the best compromise can be obtained.  

P:  If you've had astigmatisms all your life and now have complications from surgery, is it possible to get a good refraction?  

Dr. Rick Wilson:  Astigmatism complicates a refraction somewhat, but is quite common, so it should be taken care of easily. 

P:  I am from the Caribbean island of St. Vincent and the Grenadines.  One of my two-year-old twin boys has congenital glaucoma.  Last Saturday he had a refraction on the neighboring island of Barbados.  Since he can't yet read the picture chart, he was sedated.  His prescription of -5 diopters is now up to -6.5 and -7 diopters.  What does that mean in terms of the kind of vision he has?  

Dr. Rick Wilson:  I am a minus 7 diopters, so it is certainly compatible with good vision. However, if he is becoming more myopic (near sighted), it could easily be that his intraocular pressure is too high and causing his eye to expand.

P:  My son's ophthalmologist prescribed high index and transition for his glasses, but when I tried to fill the prescription I was told that I could not have both. Why was that?  

Dr. Rick Wilson:  High index means the density of the glass is high.  More bending of the light will occur than if the index were lower.  Strong glasses can then be made thinner.  I am not sure what the transition refers to, so don't know the answer to your question.

P:  Transition lenses turn darker in the sunlight.  

P:  SOLA makes a fairly high index lens with transitions.  Ask about them.

P:  My son has aniridia and glaucoma.  His glasses are -6, his intraocular pressure is 32  mm Hg in the right eye and 28 mm Hg in the left eye.  What vision would he actually have?

Dr. Rick Wilson:  Patients with aniridia usually have a best vision of 20/200 to 20/400, due to the retina not developing as it should.  Other determinants of best vision would be the condition of the cornea and whether there are changes on the surface and whether there is much nerve damage.  

P:  What would be the best type of specialist to see for my children with aniridia and glaucoma?

Dr. Rick Wilson:  A glaucoma specialist for the intraocular pressure (which, at 32 mm Hg and 28 mm Hg, is far too high), and a pediatric or low-vision specialist to maximize the vision.  

P:  If eyedrops occasionally cause blurred vision, when is the best time to be refracted? 

Dr. Rick Wilson:  Since the blurring may come at different times of the day with different drops, patients should present for a refraction at the time of day when they see the best.  Pupils either too small or too big because of medication usage throws off the vision and the refraction. 

P:  How soon after surgery, with no complications, can a patient be refracted?

Dr. Rick Wilson:  Several weeks after cataract extraction.  After a combined cataract and glaucoma operation, a lot of steroids are used topically to retard the healing of the glaucoma operation to prevent it from scarring up.  The steroids also slow down the healing of the cataract wound, so it may take two or more months after surgery to allow the cataract wound to heal and the IOP to stabilize.

P:  Should an optometrist or an ophthalmologist refract a glaucoma patient?  

Dr. Rick Wilson:  Either one should do a good job.  If the optometrist has not examined the patient, he or she should be told that glaucoma is present.  

P:  Is refraction used for adult glaucoma patients, and if so, why?  They can read the eye charts like other patients.  

Dr. Rick Wilson:  Refracting a patient just means prescribing the best glasses for them.  That can be done for children by shining a streak of light into the their eyes as they look at the light.  Various lenses are tried until the reflex is well focused.  In adults, we use the vision of the patient to tell when the light is being focused on the retina.

P:  Isn't refraction a part of an eye exam, whether or not you have glaucoma?

Dr. Rick Wilson:  It can be, but it is not necessarily done if the patient is seeing well. 

P:  What is done for an adult patient who can no longer read the eye chart?

Dr. Rick Wilson:  Then we would use the streak retinoscope, as we would for a child, or use a chart that is closer to the eye or has bigger letters.

P:  Is an aphakic patient refracted the same way as a patient who has lenses?  

Dr. Rick Wilson:  An aphake does not have a lens in the eye, so must wear very thick lenses to make up for the lack of lens and to help the cornea focus light.  With thick lenses, the distance the lens is in front of the eye is much more critical to seeing well.  Therefore, we measure the distance the trial lens was in front of the eye and furnish that information to the optician for his or her calculations.

P:  I dread refractions.  The doctor keeps asking, "Is this better or is that better?"  When vision is poor, after a while it's hard to tell any difference.  Is that a common complaint?  

Dr. Rick Wilson:  Yes, it's quite common.  If you get too tired and can't make distinctions, it is usually better to come back another day and start where you left off.

P:  For pediatric patients too young to read the eye chart, what's the difference between automated and manual refraction?  Which is more accurate?

Dr. Rick Wilson:  There is a huge range in the accuracy in the automated refractors.  It is usually best to have the refraction checked manually, if done with an automated system.

P:  How often does a glaucoma patient need to be refracted?  

Dr. Rick Wilson:  In childhood, near-sighted patients may need to change glasses more than once a year. In the middle years, glasses should not need to be changed more than every two to four years.  When cataracts start to form, the frequency of required eyeglass changes generally increases to every six months to two years.

P:  Thank you for your help,  Doctor.

Dr. Rick Wilson:  You're welcome.  Tonight's my wife's birthday, so I'm going to have to leave.  Have a good week.  Good night.  

Moderator:  Goodnight, Doctor Rick.  Happy birthday to Mrs. Wilson.  

Note: The remarks of a patient from the U.K. about the use of stem cells there prompted the following comments by Dr. Wilson.

"I had been on a panel that picked the best research among young investigators and was at the awards ceremony in Florida Saturday night.  I sat next to a M.D. from Ireland, who had received his training in England.  I was complaining that we were losing some of our best researchers in stem cell research to England, because of the very conservative stance of the Bush White House on stem cell research.  He related that in England one could do anything to a stem cell, but had to get a letter from the home office to touch a rat."

End of highlights for May 8, 2002.

On May 15, Dr. Connolly discussed "The Retina" in the Chat room. Click here for highlights of that meeting.

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