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