Inter-Eye Intraocular Pressure Asymmetries in Different Glaucoma Subtypes

Abstract

Purpose : Previous studies reported intraocular pressure (IOP) asymmetries for single types of glaucoma as well as systematic lateral IOP differences. We aimed to quantify inter-eye differences and asymmetries of IOP in different glaucoma subtypes.

Methods : We extracted the available IOP measurements of both eyes from about 60 million patients in the American Academy of Ophthalmology’s IRIS^® Registry dataset. When data for multiple visits were available, the most recent one was selected. Patients were separated by ICD-10 code into patients with glaucomatous conditions (codes H40.*) and non-glaucoma patients (absence of H40 codes). We compared the inter-eye IOP differences for the most prevalent subtypes of glaucomatous conditions including ocular hypertension, primary open-angle glaucoma (POAG), low-tension glaucoma (LTG), pigmentary glaucoma, pseudoexfoliation glaucoma, acute angle-closure glaucoma (AACG), chronic angle-closure glaucoma (CACG), and glaucoma secondary to eye trauma, inflammation and medications. T-test was performed to test if there was a systematic difference between the two eyes. Mean absolute inter-eye IOP differences were calculated to quantify the IOP asymmetry.

Results : Table 1 shows the detailed results. Approximately 15.5 million non-glaucoma patients and 2.8 million glaucoma patients with the aforementioned 10 glaucoma subtypes were selected for data analyses. The five most prevalent glaucomatous subtypes were POAG, ocular hypertension, LTG, CACG, and pseudoexfoliation glaucoma. The mean IOP of the left eye was almost identical to the mean IOP of the right eye for all subgroups, except that the left eye IOPs of non-glaucoma, LTG and pseudoexfoliation glaucoma were significantly slightly higher than the right eye IOPs. The mean absolute inter-eye IOP differences were highest for glaucoma secondary to eye trauma and inflammation (4.95 and 4.39 mmHg), followed by AACG, CACG, glaucoma secondary to medications, pseudoexfoliation glaucoma, pigmentary glaucoma, ocular hypertension and POAG (3.88, 3.20, 3.08, 2.79, 1.96, 1.95 and 1.94 mmHg), which were higher than than non-glaucoma (1.11 mmHg). The inter-eye IOP difference for LTG was in a similar range (1.17 mmHg) of non-glaucoma.

Conclusions : While systematic laterality effects were negligible, inter-eye IOP differences for different glaucoma subtypes ranged from 1.17 to 4.95 mmHg, which may imply distinct etiologies.

This is a 2020 ARVO Annual Meeting abstract.