Pluses and minuses of relaxing fixation loss criterion

Purpose. To determine the effect of relaxing the HVF 30-2 fixation loss criterion from 20% to 33%. Methods. 1,873 patients have completed VF eligibility assessment. Two out of three baseline visual fields must be normal and reliable for entry. Results. 360 pts. (19%) were ineligible due to abnormal and/or unreliable visual fields. Only 5 patients of the 1,873 (0.2%) were ineligible due to unreliability alone, and these five failed the fixation loss criterion. If the fixation loss criterion had been 20%, an additional 109 patients (5.8%) would have been excluded, and 189 patients would have needed a third VF to ascertain eligibility. Unreliable follow up VF's must be repeated. Six percent (38 of 611) follow-up VF's to date needed to be repeated due to unreliability. 21 of these 38 repeats involved patients who had failed the 20% fixation loss criterion at entry. Conclusions. Relaxing the fixation loss criterion substantially improved recruitment and decreased the burden of eligibility assessment but slightly increases the need for repeat visual fields during follow-up.