Bill Harvey: Got to see it from my angle
Author: Bill Harvey
I was asked the other day about referral of patients based upon narrow angles. There seems to be some confusion about whether to refer patients with a van Herrick grade of 2. I stated that, assuming there were no other factors of note, referral of a grade 2 angle would be inappropriate. Indeed, this would probably include most elderly patients and many hyperopes. Yet more important from a personal viewpoint, this would include me.
The confusion seems to have arisen from a sentence in the College guidelines as follows –‘Patients with peripheral anterior chamber width of one quarter or less of the corneal thickness (van Herrick grade 2) should be referred to secondary eye care services.’ Few would argue that, when the anterior chamber is less than a quarter the corneal thickness, something should be done. The problem here is that this represents grade 1. Grade 2 is where the chamber gap is one quarter to a half the corneal thickness, and the guidelines here might be better revised to state grade 1.
If we moved away from the archaic and non-linear original grading system, this sort of problem would be less likely to arise. My gap is around a third the corneal thickness and I would record it as 0.3. Ten years ago it was 0.4, and at university 0.5. By the old grading system, I would have stayed grade 2 throughout. A decimal system of recording is more responsive to changes. If the change had happened over a short time or in one eye only, I would expect some advice. Furthermore, as I approach the 0.25 grade or less, I would expect regular pressure management and some advice about looking out for prodromal symptoms.
Grading systems need to be easily standardised between practitioners but responsive enough to reflect change. The old 0 to 4 grades are no longer fit for purpose.