Question
Hello
You are a very busy person. I am afraid, You will not answer my so many questions. But you are a merciful person. So I will wait for your answers.
Question 1:
I am a patient of primary chronic open angle glaucoma and my anterior chamber angle is narrow. I have severe cataract. I am using glaucoma medicines (Travatan and Betagan), and my I.O.P. is reduced from 37 to 17 mmHg. I will need perimetry after every few months to know whether my visual field loss progression has stopped or not.
Which type of perimetry (White-on-White / Blue-on-Yellow) will be better for me? If, in cataract obstructing view of the retina, neither White-on-White perimetry nor Blue-on-Yellow perimetry can be performed reliably, then how my visual field loss progression can be evaluated? I do not want to remove cataract now, because I want to wait for few years for a combined surgery of cataract and glaucoma.
Question 2:
What are pre-requirements for perimetry? I mean, is evaluation of Visual Acuity and Refraction, necessary before perimetry?
Question 3:
Perimetry result is written on a chart. Many things are written on it. e.g. GHT, PSD, d B, Total deviation, Pattern deviation, False negative errors, False positive errors, Fixation losses, Fovea off, Strategy Sita Fast, Visual Acuity Rx Ds Dc X.
I want to know the meanings of above words. I want to understand graphs on the chart. I want to get deep information of perimetry. I want to get deep information of glaucoma. Is there any website from where I can read such deep information?
Thank You,
Best regards,
Allen.
Answer
Hi Allen,
In general you need to know the current glasses prescription, but it doesn't have to be perfect. Of course the greater the acuity the better, but you do with what you have. If your cataract is severe as you say, your ability to help fine tune your prescription may be poor and the visual field may not be very reliable or useful. Sometimes just having the cataract surgery will alter the anatomy of the angle enough to relieve some of the glaucoma and improve the acuity to make field testing reliable and useful. If you don't have faith in your eye doctor seek a second opinion for your cataract and glaucoma treatment. Perhaps the second opinion would suggest cataract surgery but not specific glaucoma surgery.
If you remain interested, I suggest you search the Internet for articles on evaluating Humphrey Visual Field reports, and there are good books out there too. Here is a link to get you started:
http://www.glaucoma-eg.org/lectures%20online_files/aashafik%20how%20to%20read%20...
But you hopefully have better things to do with your life than recreate the wheel. I wouldn't suggest relying on one visual field test, rather look at a series of them over time and probably stick to a white target.
Mitch Axelrod, OD
