FREQUENCY OF ASYMMETRIC VISUAL-FIELD DEFECTS IN NORMAL-TENSION AND HIGH-TENSION GLAUCOMA

Objective: The purpose of the study was to evaluate the frequency of a symmetric visual field loss at presentation in patients with normal-te nsion glaucoma (NTG) and high-tension glaucoma (HTG). Design: A retros pective cross-sectional study design was used. Participants: Four hund red and three NTG patients and 337 consecutive HTG patients (consecuti ve diagnoses between 1986 and 1996). Intervention: Analysis of the fre quency of unilateral field loss presentations in NTG and HTG. The visu al fields of fellow eyes were compared to determine the side of more s evere field loss. For the NTG patients, the relationship between the s ide with greater field loss and corresponding intraocular pressure (IO P) was investigated, Main Outcome Measures: Humphrey field analyzer me an defect (MD) and mean diurnal IOP. Results: In the NTG group, 101 (2 5%) patients presented with unilateral field loss. The proportion of c ases with unilateral field loss decreased with increasing age of prese ntation (chi-square test for trend = 26.9; P < 0.0001). Sixty-four per cent of the patients had unilateral field loss in the left eye. Sixty- eight percent of the cases with bilateral field loss had a higher MD i n the left eye. The diurnal IOP was estimated as 0.23 +/- 0.068 mmHg ( mean +/- SE) higher in the left eye (P = 0.001). In the HTG group, 104 (31%) patients presented with unilateral field loss. The proportion o f cases with unilateral field loss decreased with increasing age of pr esentation (chi-square test for trend = 4.6; P = 0.03). Right and left eyes had an equal chance of having field loss in unilateral cases and of being the side of more advanced field damage in bilateral cases. C onclusions: The frequency of cases with unilateral field loss was simi lar in HTG and NTG patients. Patients with unilateral field loss at pr esentation were more likely to be at the younger end of the age range, In the NTG population we studied, the left eye was more frequently th e side of onset of field loss and 2.1 times more likely to present wit h a greater field defect than the right eye. In HTG patients, right an d left eyes showed an equal chance of being the side of onset of field damage and the more affected side.