Deciding between glaucoma or physiologic cupping

October 8, 2014

Big optic nerves make me feel good. I find them easier to evaluate, and I don’t get as worked up about their respective big optic cups.

Big optic nerves make me feel good. I find them easier to evaluate, and I don’t get as worked up about their respective big optic cups. With that being said, I saw one of the biggest optic nerve heads I can recall in recent history a couple of months ago (see Figure 1). I measured it as being roughly 3 mm by 3 mm. I don’t typically quantify optic nerve sizes. Instead, I qualify them as being big, medium, or small. I made an exception, however, for this one. Now, let me tell you about the patient attached to this optic nerve.

More from Dr. Casella: Big optic cups

Case presentation

A 64-year-old African-American male presented to be “checked for new glasses.” His medical history was remarkable for type 2 diabetes and hypertension, and both were controlled with metformin and hydrochlorothiazide, respectively. His family history was remarkable for glaucoma on his mother’s side and cataracts on both sides. His corrected visual acuity was 20/20 in each eye with +1.00 DS OD and +0.75 DS OS and a +2.00 D add. His intraocular pressures (IOP) (measured by Goldmann applanation tonometry) were 26 mm Hg OD and 25 mm Hg OS at 2:15 p.m. His anterior segments were normal, and dilated fundus examination was as shown in Figure 2. At the conclusion of the examination, I told him I’d like to take some photos of his optic nerves because I had a question about the possibility of glaucoma. He basically cut me off and told me that he had already been seen for that before and was told he never needed to worry about it because his optic nerves were just big. I told him I agreed that he did have big optic nerves, but that I still had a suspicion of glaucoma (not to mention his IOP was high in both eyes). He agreed to let me take photos of his optic nerve heads and also let me schedule a follow-up appointment so that I could perform glaucoma testing and check his IOP in the morning. He requested a copy of his glasses prescription, and I have yet to see him again. 

 

Not mutually exclusive diagnoses

I may be wrong, and I know we’re looking at Figure 1 in only two dimensions, but I think the superior aspect of his left optic nerve head looks as though there is hardly any rim tissue at all. This is possibly a variant on normal, as there seems to be ample room for the 1 million or so ganglion cell fibers to spread out thinly along the rim of this enormous optic nerve. However, I’m convinced that the retinal nerve fiber layer leading to the superior aspect of this optic nerve head has a subtle wedge defect in it as well (see Figure 3), and I cannot dismiss such a correlation of suspicions. In addition, the ISNT guideline is disobeyed.

Is the ISNT rule helpful?

So, given this evidence (in addition to the presence of ocular hypertension), do I think he has glaucoma or physiological cupping? I believe the answer is very likely both, and this case really made me think about how I tend to construe glaucoma and physiologic cupping as mutually exclusive diagnoses. With an optic nerve head that measures 3 mm, I’m sure there was a large cup to begin with, but I’ll bet that if I had access to the left optic nerve head 25 years ago, I’d see a little more rim tissue superiorly.

My efforts to attain previous optic nerve head photos have thus far been unsuccessful, but I did manage to reach an optometrist on the phone who had seen this patient before. He actually told me that he wanted to treat the patient for glaucoma and had discovered a visual field defect in the left eye. The patient never returned to him, either.

I’m worried about this patient because he is only 64 and in reasonably decent health. If the glaucoma that I suspect goes untreated for some time, he could really stand to lose significant vision. I have called him twice and sent him a certified letter. I also mentioned these findings in the letter to his primary-care physician stating that he had no diabetic retinopathy. I hope he decides to come back soon.

Optic nerves can look however they want to look, and differentiating variants on normal from the presence of disease is often challenging. However, dealing with the patients attached to these eyes is often the hardest and most troublesome part.