Purpose:
To describe the in vivo morphology of the trabecular meshwork (TM) and Schlemm's canal (SC) area in normal, glaucoma suspect and glaucomatous eyes using FD ASOCT.
Methods:
Thirty three consecutive normal (N), glaucoma suspect (GS) and glaucoma (G) subjects were imaged at four limbal quadrants (superior, inferior, nasal and temporal) using the Angle Scan Mode of AS FDOCT (Optovue, Inc., Fremont, CA). The highest quality images in which SC could be outlined for each of the quadrants were analyzed with the standard automated software. A qualitative assessment of the images was done by two investigators, who evaluated for the presence of intrascleral vessels and channels, communications between the TM and the uveoscleral pathway, and images suggestive of filtration over the non-filtering TM (NFTM). A total of 147 images were analyzed.
Results:
There was a significant age difference among the 3 groups: N(n=64), 34.4±8.5; GS(n=29), 62.3±9.1; and G(n=54), 58.3±12.3 p≤001. The SC area was measured and compared among groups: N vs G (0.03±0.01 vs 0.01± 0.01 mm2, p<0.01); N vs. GS (0.03 ±0.01 vs 0.02±0.03 mm2, p=0.001); GS vs G (0.02 ±.03 vs 0.01±0.01 mm2, p=0.14). A prominent Schwalbe’s line(SL) was found in 20.6% of the N eyes and 27.7% of the G group. In exfoliative glaucoma eyes (4/17), the SL was more prominent and presented higher signal density. Thirty one (20%) of the 147 images were suggestive of possible communications between the TM and the uveoscleral pathway and of filtration occurring across the NFTM.
Conclusions:
The anatomy of the TM pathway and SC can be visualized and objectively measured using AS FDOCT. There was a significant difference in the SC area related to age and possibly glaucoma.
Keywords: anterior segment • aqueous • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)