The amount of intraocular pressure rise during pharmacological pupillary dilatation is an indicator of the likelihood of future progression of glaucoma.

Aim: To determine if there is a relationship between the amount of increase in IOP following dilatation with a cycloplegic agent and the future course of glaucoma.

Method: A retrospective chart review of 100 eyes from 55 subjects with open-angle glaucoma who had had IOP measured before and after pharmacological pupillary dilatation was performed to establish the rate of progression of glaucoma, based on serial evaluation of the visual fields using the glaucoma staging system 2 (GSS 2), and optic discs using the disc damage likelihood scale (DDLS). Progressive visual field loss was defined as an increase of two or more stages with the GSS 2 and progressive deterioration of the disc was defined as an increase of two or more stages with the DDLS. Mean follow-up time was 7.2 years.

Results: A total of 26 eyes showed glaucomatous progression. The likelihood of progression of glaucoma was related to the amount of IOP increase after pharmacological pupillary dilatation. For every 1 mmHg increase in IOP, the odds of progression increased 24% (p = 0.008). The likelihood of progression of glaucoma, however, was not related to the baseline IOP, which was 20.63 mmHg (SD = 4.59 mmHg) in those showing deterioration of disc or field and 19.72 mmHg (SD = 5.32 mmHg) in those not worsening according to our definition.

Conclusion: In patients with open-angle glaucoma, the amount of increase in IOP caused by pharmacological pupillary dilatation is related to the likelihood of future progression of glaucoma.