Purpose:
To utilize anterior segment OCT to identify patients prone toward ocular hypertension after intravitreal triamcinolone injection (IVTI). A circumferential pre-trabecular anatomic stricture defined as the angle recess (AR) can be imaged with anterior segment OCT (AS-OCT). Patients undergoing intravitreal injections of triamcinolone were measured by AS-OCT to investigate the association of AR size with post-injection IOP responses.
Methods:
All IVTI from 2002-05 with AS-OCT images were included. AR was obtained by masked physicians using Stratus OCT retinal thickness analyzer caliper to measure the axis between the anterior-most prominence of the iris root and posterior cornea. IOPs from 1 mo pre- to 6 mo post-injection were assessed for IOP rise (Δ) and maximal IOP (max) into 3 categories, minimal (IOPmax below 21 mm Hg and/or IOPΔ ≤ 5 mm Hg), moderate (IOPmax 21-29/IOPΔ 6-14), and severe (IOPmax above 30/IOPΔ ≥15). Unpaired t-test and linear regression analysis were applied.
Results:
Twenty-six eyes met criteria: 11 (42.3%) with minimal, 11 (42.3%) moderate, and 4 (15.4%) severe IOP responses. Corresponding mean AR widths were 319 ± 30.8 (sem)µm, 281 ± 22.0µm, and 138 ± 20.3µm, respectively. The difference in AR width between minimal- and moderate-IOP responders was not significant (p = 0.33), but was between moderate- and severe-responders (p=0.003), and minimal- and severe-responders (p = 0.005). Five of the 6 patients with pressure ≥29 mm Hg had AR below 200µm (Figure: R=0.45; p=0.003).
Conclusions:
These preliminary results appear to affirm the inferred inverse relationship between the anatomic AR size and IOP rise after intravitreal steroid injection. AR can be measured with both time-domain and spectral-domain OCT technology, and should help identify patients at risk of a steroid-associated IOP spike. Anterior segment screening would be a natural extension of OCT in practices routinely using this technology to monitor macular edema. Larger studies should help refine our understanding of this relationship.
Keywords: drug toxicity/drug effects • intraocular pressure • imaging/image analysis: clinical