Purpose  Using MicroPerimeter MP-1 to compare the fixation behavior in early and moderate primary open-angle glaucoma (POAG) and chronic angle-closure glaucoma (CACG).

Methods  57 early and moderate glaucoma eyes (39 POAG, 18 CACG) and 22 normal control eyes were enrolled prospectively. The stability and location of the fixation in each subject eye were recorded by the macula 10° program of the microperimetry (MP-1). Fixation behavior was studied among groups. The correlation between the fixation behavior and the retinal sensitivity was analyzed.

Results  Fixation instability was detected in both POAG and CACG groups (POAG vs control, P=0.016; CACG vs control, P=0.036). However, there was no difference between POAG and CACG groups (P=0.680). In POAG group, fixation stability correlated with all the mean macular sensitivity parameters in the central 10° (r = 0.416, P = 0.008), 6° (r = 0.401, P = 0.011), 2° (r = 0.376, P = 0.018), inferotemporal (r = 0.399, P = 0.012) and inferonasal (r = 0.387, P = 0.015) quadrants of the central 6°. None such a correlation was observed in CACG group (P>0.05). 3 CACG eyes failed to maintain “predominantly central fixation” and their preferred retinal loci (PRL) were either superior or nasal to the fovea.

Conclusions  Fixation instability manifested in early and moderate glaucoma eyes. The mechanism of this phenomenon may be different in POAG and CACG. Analyzing the fixation stability and PRL may help to diagnose glaucoma in an earlier stage, hence improve the management.