[Seasonal variation of intraocular pressure after trabeculotomy]

The author reviewed the seasonal variation of intraocular pressure (IOP) in primary open angle glaucoma or late type developmental glaucoma to investigate possible relationships among seasonal variation of IOP, progression of visual field defects and the follow-up period between 53 eyes of 39 subjects with successful trabeculotomy (trabeculotomy group) and 45 eyes of 31 subjects with only medication (no operation group). IOPs in both groups were inclined to be low in summer and high in winter. Maximum seasonal variation of IOP and standard deviation of IOP during all follow-up periods which showed the degree of seasonal variation of IOP had no significant difference between the trabeculotomy group and the no operation group. These results showed that seasonal variation of IOP was not reduced even by successful trabeculotomy. The maximum seasonal variation of IOP and standard deviation of IOP had a tendency to be bigger in cases with progression of visual field defects than in cases with no progression of visual field defects, in both groups. Therefore, seasonal variation of IOP may be an important factor influencing the progression of visual field defects.