Does IOP Affect the Clinician's Decision to Modify Glaucoma Management?

Abstract

Purpose: : To determine the importance of IOP on clinician’s decision to modify glaucoma management.

Methods: : Charts of 201 patients with the diagnosis of glaucoma or glaucoma suspect, followed for at least 3 years with a minimum of 5 HVF (24-2 or 30-2) tests and 3 HRT II examinations were reviewed. For each patient, the eye with the higher Glaucoma Staging System (GSS) score was used in the analysis. Eyes were divided into three groups according to stage at initial presentation: (A) stage 0; (B) stage 1-2, (C) stage 3-4. Glaucoma progression based on clinical impression and time from baseline to change in management was recorded. Mean IOP, IOP variation and yearly IOP change (modeled linearly) were compared using 2-way ANOVA across glaucoma stages: 1) by clinician's impression of progression, 2) by change in management status. Kaplan Meier survival analysis for time of change in management for each disease stage group was performed. Logistic regression with dependent variable either the progression status or the change in management status and independent variables IOP parameters and disease stage was performed.

Results: : Mean (+SD) patient age was 69 (+14) years and follow-up period was 6.2 (+2.3) years (2.3 - 14.3). 70 patients had stage 0 disease, 69 had stage 1-2 disease, and 62 had stage 3-4 disease. Progression rates differed across disease stages (8.6%, 26.1% and 21% for stages 0, 1-2 and 3-4 respectively, p<0.005 Fisher's chi square). Mean IOP was different between disease stage groups (P<0.0003) with stage 0 eyes having the highest IOP and stage 3-4 eyes the lowest. There were no differences in mean IOP in patients who 1) did and did not progress by clinician's impression, 2) did and did not have a change in management status, overall and between groups (p>0.05). IOP variability and yearly IOP change did not show significant differences (p>0.05 for all comparisons) across stages alone or in combination with 1) progression status, 2) change in management status. None of the IOP parameters predicted progression or change in intervention (p>0.05) while disease stage did (p<0.05 Logistic regression). Survival analysis revealed that the time to intervention was longest for patients with stage 0 disease (p<0.01 Cox-Mantel).

Keywords: intraocular pressure • optic nerve • visual fields