Glaucoma Treatment, When To Begin ?

glaucoma1Recently an ophthalmologist in a developing country asked me when I would start a patient with ocular hypertension ( mid-20’s IOP and a normal cup / disc ratio ) on therapy. I wanted to follow up about that. Perhaps this would be a good conversation to have with eye care providers in emerging countries. My experience is we don’t do such a good job of treating glaucoma patients in the developing world.  As we all know, once you are blind from glaucoma, no one anywhere can restore your vision.

Usually I do not think you should start any glaucoma drops as a result of one mildly elevated IOP reading and a normal disc. There obviously are exceptions. If possible, you should have the patient come back several times to recheck the IOP and to get a better idea what is going on with that patient. I am aware that is not always possible.

As we all know, there is a diurnal curve with the IOP which means usually there is some up and down variation in the IOP. Generally there is even more variation in someone who does indeed have glaucoma. So again checking the IOP a lot is quite important to understand what is happening with your patient and their IOP. The IOP may be OK when you check it but 8 mm higher later in the day. Checking the IOP frequently is good.

 

What you do not want to do is to treat ( chase ) the number. Everyone with an IOP over (say ) 22 mm does not have glaucoma and does not need treatment. There are also patients that actually have glaucoma but a “normal “ IOP ( normal tension glaucoma ). If the patient has a ‘’normal IOP” and a healthy ( pink ) large cup /disc that is similar ( symmetrical ) to the other eye ( nerve head ) may be it’s not glaucoma. Adding more and more medicine ( drops ) is often not necessary and may be unproductive. If a patient has a normal healthy disc often a IOP in the mid-20’s is acceptable. What we need to do is to educate the patient to use their current drops every day, every day. Compliance / adherence is not good with glaucoma in either the industrialized or emerging world. I am quick to perform laser trabeculoplasty if a patient truly has glaucoma. You must tell the patient that the laser surgery will not restore their vision.

I often see patients who may not even have glaucoma yet they are on two, three drops ( agents ) and perhaps Diamox ( acetazoamide ) orally. Often these patients have a large pink cup/disc ratio with a healthy neuroretinal rim and the IOP has never been recorded over 22 mm.  Not uncommon presentation. In this case I would recommend a quick taper ( discontinue ) of most of the drops and see what happens to the IOP.

Get a ocular history: “Anyone in family with glaucoma and have to use drops every day, every day?  Did anyone in the family go blind’,“ which often suggests glaucoma.  A negative family history can sometimes be helpful in determining not to start the patient on treatment but to follow the patient.

If available you can certainly use the OCT to look at the retinal nerve fiber layer  ( RNFL ) thickness. This is often quite useful to identify glaucoma suspect ( large cup / disc ratio but “normal” IOP ), ocular hypertension, or early glaucoma. It is an objective test and requires the patient’s brief cooperation but no feed back, unlike a visual field test which requires an alert, cooperative patient.  Visual fields  testing ( perimetry) is a subjective test. Often the first visual fields are not valid ( worthless )  and will need to be repeated. The patient needs to “ learn “ how to take the test. The RNFL test is an objective test --- basically green is good, red is bad. Red indicates thinning of the nerve fiber layer which usually means glaucoma.

Unless the patient has severe, advanced glaucoma with a quite high IOP ( > 35 mm ), starting the patient on one drop ( agent ) only may be the correct choice. Perhaps timolol ( usually available and cheap ) once daily in the morning or a prostaglandin analog ( latanoprost ) at night. You should have the patient come back in 3 - 4 weeks to see what is the IOP. Some patients may simply not respond to whatever drops you have started. Not all patients respond to all drops the same.

If the IOP is consistently over 25 mm, then in the developing world, you might consider starting some treatment. This requires checking the IOP more than once. In the States many ophthalmologist will simply follow their patient with normal discs / visual fields and a negative family history unless the IOP goes over 30 mm. Perhaps a IOP of 25 mm might be a good number ( trigger ) to start treatment in the developing world. Some physicians think the patient is more likely to come back for follow up if you start them on treatment ( drops ). I don’t know if that is correct.

As we know, probably the three biggest risk factors for developing glaucoma are: #1. African ancestry  
#2. family history of glaucoma
#3. getting older --- many folks don’t have glaucoma at age 45 but will when they are 50 or 60 or 70 years.

I am more aggressive with treatment, etc. if the patient has African ancestry.

Patients need to be educated about glaucoma which is the leading cause of blindness in black folks and the second leading cause of blindness in the world. Bad disease. In the developing world glaucoma patients often present with bilateral optic atrophy, poor vision OU, and markedly constricted visual fields.  I have seen black patients in their early 30’s who have bilateral optic atrophy and poor vision secondary to glaucoma ( gone blind ).

Peace, Baxter

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