Sectorization of the central 30 degrees visual field in glaucoma.

PURPOSE

To determine an optimal sector pattern of the central 30 degrees visual field in glaucoma by mathematically analyzing the visual field data of primary open-angle glaucoma (POAG) without any assumption such as the retinal nerve fiber layer anatomy.

METHODS

One hundred three visual fields of the 30-2 program of the Humphrey Field Analyzer obtained from 103 POAG patients of early to moderately advanced stage were included. Based on the interpoint correlation of deviation of the measured threshold value from the age-corrected normal reference value (total deviation, STATPAC), test points of the 30-2 program were mathematically clustered using the VARCLUS procedure, a new clustering algorithm developed by the SAS Institute. The sector value, which summarizes the visual field performance of the clustered test points (sector), also was calculated.

RESULTS

The 30 degrees central visual field was divided into 15 sectors consisting of at least 3 points. The distribution of sectors was compatible with the projection of nerve fiber layers. There was no sector extending over the horizontal meridian, but the sector pattern was not completely symmetrical around it. Linear regression analysis of the sector values against the mean deviation (STATPAC) suggested that the index is useful in following visual field performance of each sector.

CONCLUSION

The sector pattern and sector values obtained were considered useful in studying the visual field data of glaucoma.