Purchase this article with an account.
Shirley Ke, Alan Le, Joseph Caprioli, JoAnn A. Giaconi, Kouros Nouri-Mahdavi, Simon K Law, Laura Bonelli, Anne L Coleman, Joseph Demer; Magnetic Resonance Imaging (MRI) Demonstrates Smaller Orbital Size in Asians Who Have Primary Open Angle Glaucoma (POAG) Without Statistically Elevated Intraocular Pressure (IOP). Invest. Ophthalmol. Vis. Sci. 2020;61(7):2346.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Asian patients with POAG are more likely than Caucasians with POAG never to have had IOP exceeding the statistical normal range observed in healthy people. Patients with POAG have less posterior orbital fat than controls. We hypothesized there are racial and disease-related variations in orbital dimensions. We investigated healthy controls and patients with POAG in whom maximum untreated IOP was never measured to exceed 21mmHg.
We used surface coils to obtain quasi-coronal MRI at 312µm resolution in contiguous 2mm thick planes that spanned the entire orbit in target-controlled central gaze in 3 racial groups: Asian (11 patients, 24 healthy controls), Caucasian (22 patients, 57 controls), and African American (14 controls). Semi-automated, blinded analysis was performed by independent investigators using ImageJ scripts to determine average orbital width, height, and cross-sectional area.
Analysis of variance demonstrated that orbital cross-sectional area of each plane varied significantly by race in healthy controls: largest for Blacks, next Caucasians, and least in Asians. Differences were greatest in the 10mm region just posterior to the globe. For example, at 4mm posterior, mean orbital cross-section (±SEM) was 813.5±34mm2 for Blacks, 627.4±13 mm2 for Caucasians, and 606.5±19 mm2 for Asians. Patients with POAG had horizontally narrower and vertically shorter orbits than racially-matched controls (Asians, p<0.0001, Caucasian P=0.02). Orbit cross-sectional area in Asians with POAG averaged 26.3mm2 less than in Asian controls (P<0.0001), but Caucasian patients were similar to controls (P=0.8).
Patients with POAG in whom maximum untreated intraocular pressure never exceeded 21mHg have orbits significantly smaller in horizontal and vertical dimensions than racially-matched controls; orbital cross-sectional area is significantly smaller in Asian patients than in Asian controls. Smaller orbital size might be related to the development of POAG, and to the predominance of lower IOP among Asian patients who have POAG.
This is a 2020 ARVO Annual Meeting abstract.
This PDF is available to Subscribers Only