Response to Shah et al

Sir, We thank Shah et al1 for their interest in the Portsmouth Glaucoma Refinement Scheme.2 The scheme also uses Van Herick grading for anterior chamber depth—all patients with a Van Herick peripheral limbal anterior chamber depth of less than 25% of corneal thickness were referred to the virtual clinic for assessment by an ophthalmologist. Approximately 10% of all of those accepted from the Refinement Scheme virtual clinic to HES (from a total of 11 out of 100 referred to the virtual clinic, from our audit) were due to narrow angles suspected through Van Herick grading. Of these, 25% subsequently required laser peripheral iridotomy, slightly higher than the 17% positive predictive value, for the suggestion of occludable angles by an initial Van Herick test, outlined by Foster.3