Tonometry in the general practice setting (II): Which cut-off point for referral--for which patients?

A tonometry study comparing Tono-Pen with Goldmann applanation tonometry in a general practice setting revealed four cases of ocular hypertension in 132 patients. Two of the 4 patients required further ophthalmological care after referral. None of these patients, but 4 patients with no ocular hypertension, would have been referred for follow-up if referral had been made on the basis of the single reading made by the general practitioner. Tonometry readings are subject to considerable random variation, and the implications for a cut-off policy in general practice is discussed. Associations between ocular hypertension and known risk factors are weak and offer limited help in selecting asymptomatic patients for measurement. Systematic screening should not be a routine. The cut-off point should be kept low to avoid false reassurance of glaucoma patients, possibly as low as 17 mmHg. Multiple measurements may limit the number of referrals if the readings remain low.