FAQs / I Was Wondering What a Few Point Difference Could Make When the Glaucoma Has Not Progressed Since Diagnosis?

QUESTION:

So my base OCT and the next one a year later (just recently) show NO progression of glaucoma – it is all relative though as my optic nerve had a lot of damage when I was diagnosed. The ophthalmologist wants me to be on latanoprost / timOlol combo. For two and a half years since diagnosis I was just on latanoprost which was working. That combo has side effects for me and I was reasonably happy with just the latanaprost and had no side effects that I could detect anyway. He wanted my IOP down. I was wondering what a few point difference could make when the glaucoma has not progressed since diagnosis.

ANSWER:

OCTs are a wonderful method of detecting subtle changes in the nerve fiber layer in the early and moderate stages of glaucoma. Unfortunately, in the later stages this technology is nearly useless. Once the nerve fiber layer thickness reaches 70 micrometers or less (commonly seen in advanced glaucoma) the OCT will not reliably detect further progressive loss even if vision is being rapidly compromised. At later stages in glaucoma there is no substitute for the much maligned threshold visual field testing which, unfortunately, must be repeated multiple times per year (not just annually) in order to detect real visual field loss.

With regard to your question about the importance of further IOP reduction the medical literature is clear that more advanced glaucoma requires lower target pressures. What that target is for each individual, however, is only discovered after the fact. In essence glaucoma is treated by choosing a target IOP based on many factors (age, severity of visual field and NFL loss, family history, medical conditions, etc.) then the NFL and visual fields are monitored. If no progression is detected the then target is considered adequate. If, however, progression is detected then the target IOP is reduced another 15-20% until the rate of progression is adequately reduced.

As you can imagine, the success of such an iterative process is severely limited by the variability inherent in all glaucoma testing (especially IOP and visual fields). It takes at least three measurements to separate out a trend from the noise of inter-test variability. For this reason I recommend that my own patients with glaucoma obtain visual field and/or OCTs a minimum of twice yearly and as frequently as every three months. I also encourage home IOP monitoring for those who can afford it. Hopefully such devices will be both affordable and covered by insurance over the next few years.

Warm regards,
David Richardson, MD
Patient-Focused Ophthalmologist

San Marino Eye
2020 Huntington Drive
San Marino, CA 91108
626.289.7856

Patient-Focused Websites:
New-Glaucoma-Treatments.com
About-Eyes.com

Date: Sun, Mar 15, 2015 at 11:37 PM

Posted in: Glaucoma, Loss Of Vision [Others]