Glaucoma is the second leading cause of blindness worldwide, cataracts being number one. Unfortunately glaucoma is often poorly diagnosed and managed. With the next several blogs, I would like to lists some glaucoma caveats that hopefully will prove useful for teaching, discussion, and management in the developing world and elsewhere. Most of what I am going to say is well known by all the readers. However glauoma is a bad disease in the developing world and patients often show up late with bilateral blindness. Perhaps some of these observations / suggestions from the developing world might prove useful.
Some of what I’m going to say might be correct for a middle income country but not for a low-income country. Or vice versa. How you treat / manage glaucoma really depends on where you are and who your patient is. If you are treating an upper middle class patient in the capital your options / approach might be different than if you are in a quite rural isolated area treating someone with advanced disease and no access to any future drops / treatment.
My good friend Jim Stander MD has visited many, many eye training institutions all over the world for many years. He has a one week glaucoma course that he has taught to prehaps hundreds of developing - world eye residents over many years. He states that many eye residents are unfortunately not being trained thoroughly in glaucoma --- diagnosis / management, etc. Spending time training eye health care providers on glaucoma is time well spent in the developing world ( middle income or low income ).
As we all know if you are bilaterally blind from glaucoma then your visual loss is often more marked / severe than with bilateral maculopathy or with dense advanced cataracts. If you are blind from glaucoma then you probably have wiped out both your central and peripheral visual fields. Many patients with bilateral macular scars can still function at a high level which is certainly not true with glaucoma blindness. The advanced glaucoma patient often has trouble walking ( ambulating ). He can’t find your examining chair. If you try to shake hands with him ( her ) , he doesn’t see your hand. You don’t need a formal visual field to diagnose a marked bilateral visual field constriction in these patients. You can often make the diagnosis of severe advanced bilateral glaucoma when they attempt to walk into the clinic.
#1.A large cup / disc ( C/D ) ratio does not always mean glaucoma. A patient might have a cup / disc ratio of 0.6 or 0.7 and still be normal. Sometimes looking at the old chart, these patients have never had a IOP reading of over 22 mm . Are the discs symmetrical? That’s a big one. Symmetrical C/D ratios suggest physiological ( normal ) discs. As we all know, any C / D ratio difference of 0.2 or more often suggests glaucoma. Are the bilateral neuroretinal rims intact and pink --- no notching ?
Glaucoma is often overdiagnosed. Not all optic atrophy is glaucoma. Unilateral optic atrophy may not need treatment. Over the years I have seen many, many patients on two or more anti-glaucoma drops who I did not think had glaucoma. If possible, you can suggest slowly tapering the drops and have the patient come back for further observation. You can also eventually stop all drops in just one eye and have them come back for re-check. Or if they are on timolol then get the patient to just use it in the morning only ( taper ) and observe ( follow ). Sometimes you must be diplomatic , telling your host that you do not think their patient has glaucoma.
#1. If you have a large disc, then you will often have a large cup. Look at the disc using the smallest light ( circle ) with a direct ophthalmoscope. If the disc is actually larger than the circular image from the ophthalmoscope, then that’s probably a large disc. In that case don’t be surprised if the cup is also large. That’s a trick I learned from Jim Standerfer MD.
#2. Many eye residents are not taught how to perform gonioscopy There is a video available < www.gonioscopy.org>. Every eye clinic should try to have a three mirror diagnostic lens available ( great gift ) and to use it. K- Y Jelly can be used as a gonioscopic / lubricant agent ( like methycellulose, etc. ).
You must examine a lot of iridocorneal angles before you can appreciate the normal variations of the trabecular meshwork, iris configuration / insertion, etc. To appreciate a narrow angle, primary chronic angle closure ( asymptomatic ), peripheral synechiae, or an occludable angle you have first to look at a lot of normal eyes. If you are not quite comfortable with the normal anatomy ( variations ) then good luck on doing a correct laser trabeculoplasty. Previously I have had two glaucoma specialists in the States comment that many ophthalmologists often are not directing their laser shots to the trabecular meshwork but blasting the peripheral cornea, peripheral iris, etc. So lasering the wrong area can be a problem / concern everywhere. You have got to know the normal anatomy and the filtering angle variations. The Color Atlas Of Gonioscopy 2nd edition is available through the AAO.
#3. Depending on the location / situation glaucoma is sometimes best treated initially with laser surgery or incisional surgery rather than drops. Drops are often expensive / unavailable. I often see patients with an initial presentation of advanced severe bilateral glaucoma, often with an IOP over 35 mm OU. I am quick to do bilateral laser trabeculoplasty on these patients -- often at the first examination and also start them on drops. Patients should be advised that neither the drops nor the laser or incisional surgery will improve the vision. As we all know, drops or surgery may prevent more loss ( progression ) of vision. You often need to repeat this message on several occasions. No glaucoma patient wants to hear / accept that message. No drops, ointment , glasses , surgery, etc. will improve the vision. We all know that, but the patient needs to be told that several times. What a horrible disease.
#4. Removing a cataract will often reduce the IOP by 1 - 3 mm, sometimes more. That’s often as much as you get with a second drop ( agent ). Therefore a patient with both cataracts and elevated IOP may also have a reduction in IOP post-op cataract surgery.
#5. If you are already on a systemic beta-blocker, then you might not get much additional help with adding a topical beta- blocker ( timolol ). Not uncommon to see patients on both systemic and topical beta-blockers.
#6. The cheapest anti-glaucoma medicines are timolol and pilocarpine. Pilocarpine 4% bid is sometimes not a bad choice especially in the pseudophakic patient. If you have a patient on an anti-glaucoma drop, then you must mention the “ G “ word. Many patients are on several drops and no one has ever told the patient that they have glaucoma.
#7. Patients with African ancestry often develop glaucoma earlier, are more difficult to control, and often show quicker progression.
#8. Ask about a family history of glaucoma. Did anyone in your family go blind, is a good question. Anyone in your family using drops every day, every day? Ask the patient to write down the name of the drops their sibling is using and to let you know. If your patient has glaucoma, then you should suggest their siblings be checked for glaucoma every two years. Even if they are in a different country. It’s not an emergency but your patient should be told her / his siblings need to be checked for glaucoma, not just once.
More to come later. I know I have mentioned some quite basic principles concerning glaucoma but many of these suggestions are not always appreciated by eye health care workers in some developing areas.