Sectorization of central 10-deg visual field in open-angle glaucoma

Purpose: To obtain an optimal clustering of the test points of the Humphrey 10-2 program in glaucoma for brief evaluation of the visual field characteristics in the central 10-deg field and to examine its clinical usefulness. Methods: We applied VARCLUS, a new clustering algorithm, to 379 visual fields obtained with the 10-2 program of the Humphey perimeter from 211 eyes of 140 normal-tension glaucoma (NTG) patients and 168 eyes of 111 primary open-angle glaucoma (POAG) patients with the mean deviation (Statpac 2) –15 dB. Based on the interpoint correlation of deviation of the measured threshold value from age-corrected normal reference (total deviation), the 68 2-deg grid points were mathematically clustered, i.e., the central 10-deg visual field was divided into sectors. Between 76 eyes of 76 POAG patients with the peak intraocular pressure (IOP) 25 mmHg (high-tension group) and 85 eyes of 85 NTG patients with the peak IOP 18 mmHg (low-tension group) which had similar mean deviation and age, the mean of total deviation in each obtained sector was compared. Results: The central 10-deg visual field in glaucoma was divided into 10 sectors. The sector pattern obtained was compatible with the projection of nerve fiber layers, with no sectors extending over the horizontal meridian, and it was not completely symmetrical around the horizontal meridian. A group of sectors in the superior arcuate area was significantly more depressed in the low-tension group, while a group of sectors in the inferior centrocecal area was significantly more depressed in the high-tension group. Conclusion: We suggest that the sector pattern obtained here is useful to provide brief evaluation of the result of the 10-2 program and that it may be used in the study of the central visual field in glaucoma.