Purchase this article with an account.
Joshua C. Priluck, Deepak P. Edward; Determination Of Optimal Limbal Location And Imaging Conditions For Identifying Schwalbe's Line And Scleral Spur Using Spectral-domain Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1745.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
This study examined the ability of spectral-domain anterior segment optical coherence tomography (AS-OCT) to consistently identify anterior chamber angle landmarks and determine optimal conditions during testing to identify these landmarks.
This observational study included 30 subjects (age range: 18-65 years) with no known ocular disease. AS-OCT was performed using the RTVue-100 cornea anterior module (Optovue, Fremont, CA). Scans were performed on the right eye in four quadrants. Baseline conditions included: the room lights off, target light on, and the limbus perpendicular to the coherence light beam. Scans of the temporal quadrant were repeated after varying the following conditions: room light, target light, use of an eyelid speculum, and gaze direction. Scans were reviewed twice for the identification of two landmarks: Schwalbe’s line (SL) and scleral spur (SS) based on the termination of corneal endothelium and posterior aspect of trabecular meshwork respectively. Pearson’s Chi-Square was calculated to compare the varying testing conditions. Intraobserver reproducibility scans were also tested using Cohen’s kappa comparison.
SL and SS were identified most consistently in the temporal quadrant (SL: 100%, SS: 96.7%) followed by the nasal (100%, 93.3%), inferior (73.3%, 33.3%), and superior quadrants (73.3%, 26.7%). Abduction, adduction, or standard positioning did not affect identification of SL (p=0.357) or SS (p=0.51). Modifying other variables including keeping the room and target light on, room light off/target light on, and all lights off did not affect identification of SL (p=0.519) or SS (p=0.833). An eyelid speculum significantly improved SS identification in the superior quadrant (26.7% without the speculum to 60% with; p=0.018). Intraobserver reproducibility comparing repeated interpretation of scans by a single observer found Cohen’s kappa value's > 0.6 for SS and SL in all 4 quadrants.
The RTVue-100 CAM can identify SL and SS in the temporal and nasal quadrants and the use of an eyelid speculum improves visualization of these landmarks in the superior quadrant. Intraobserver evaluation of landmarks is reproducible in all quadrants. Spectral-domain AS-OCT may prove a useful tool to manage and screen for disease of the anterior chamber angle, but accurate landmark identification is not reliable in all quadrants; eyelid re-positioning is one technique that improves landmark detection.
This PDF is available to Subscribers Only