The cyclopentolate provocative test in suspected or untreated open-angle glaucoma. I. Effect on intraocular pressure.

The mydriasis provocative test with 1% cyclopentolate (CPT) was performed on 218 patients with suspected or untreated open-angle glaucoma, on 431 eyes in all. Gonioscopy was performed before and during the test to ensure that te chamber angles were open throughout. The effect of cyclopentolate on intraocular pressure (10P) in these eyes is reported in the present paper. The mean change in IOP (+/-SD) During CPT was +2.5 +/- 3.1 mmHg in the glaucoma group (196 eyes), +0.4 +/- 2.5 mmHg in the group with suspicion of open-angle glaucoma (235 eyes), and +1.4 +/- 2.9 mmHg in the total series. The difference in IOP change between the groups with glaucoma and suspected glaucoma is statistically highly significant. The incidence of positive responses (IOP rise larger than or equal to 8 mmHg) in the glaucoma group (8.7%: 17 eyes) was significantly higher than in the suspicion group (1.7%: 4 eyes). Significant IOP elevations in the total series were demonstrated in 21 eyes of 18 patients (4.9%). Including the borderline cases, IOP elevations larger than or equal to 5 mmHg were also significantly more frequent in eyes with glaucoma (24.0%: 47 eyes) than in eyes with suspected glaucoma (11.9%: 28 eyes). The occurrence and magnitude of positive responses were not dependent on the initial IOP level. Further analysis of the responder group and clinical studies of the mechanism of IOP elevation on the same patients are presented in parts II and III.