Eye Dynamics & Engineering Network (EDEN) Consortium: Study Design and Baseline Description

Abstract

Purpose : We characterized the variation in intraocular pressure (IOP) in normal subjects. We report the study design of the Eye Dynamics and Engineering Network (EDEN) consortium, a description of study subjects, and IOP outcome measures at baseline.

Methods : These subjects were enrolled a prospective, randomized, multi-center trial to assess aqueous humor dynamic (AHD) traits and response to glaucoma medications in the same individuals. We measured IOP by tonometry, aqueous humor flow by fluorophotometry, outflow facility by 2-minute pneumatonometry (Model 30 Classic, Medtronic), and episcleral venous pressure by episcleral venomanometry. The PhenX Toolkit (www.phenxtoolkit.org) was used to assess body mass index (BMI), neck circumference, systemic disease, lifetime tobacco use, blood pressure, and systemic medications. Central cornea thickness (CCT) and ocular dimensions were measured by pachymetry and ocular biometry, respectively. Visit-to-visit IOP difference at five different times was classified as differences in IOP < 3 mmHg, between 3 – 5 mmHg, and > 5 mmHg. Data were assessed by univariate analyses and Pearson correlation for IOP difference between eyes and between visits.

Results : IOP was measured in 118 normal subjects at baseline AHD measurements and three prior visits during enrollment. Mean age was 55.3 ± 8.9 years (± SD, range 40 – 81 years), 88 were females and 30 were males, and self-reported ethnoracial status with 100 Caucasians, 12 Blacks, and 6 other. CCT was similar between eyes (553 ± 36 µm OD, 552 ± 37 µm OS, p = 0.9206). Axial length was similar between eyes (23.9 ± 1.2 µm OD, 23.8 ± 1.2 µm OS, p = 0.5555). The Pearson correlation coefficient between IOP in right and left eyes was r = 0.91 (95% CI:0.87, 0.93; p < 0.0001) with similar results on three repeated IOP measurements at two study visits. The visit-to-visit IOP difference from five repeated IOP measurements (right eye only) in 96 subjects (81%) was < 3 mmHg difference, in 18 subjects (15%) was 3 – 5 mmHg difference, and in 4 subjects (4%) was > 5 mmHg difference. There was no significant effect of study site, age, sex, race, CCT, BMI, neck circumference, tobacco use, systemic disease or medications on IOP outcomes (stepwise regression analysis, all p ≥ 0.05).

Conclusions : In the EDEN consortium, 15% of normal subjects have IOP difference of 3-5 mmHg between visits and 4% of normal subjects had > 5 mmHg between visits.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.