Comparison of Physiologic Mydriasis Versus Pharmacologic Mydriasis on Anterior Chamber Angle Measurements Using Spectral Domain OCT
Purpose
To compare the effects of physiologic pupillary dilation vs. pharmacologic pupil dilation on anterior chamber angle (ACA) measurements obtained with spectral-domain optical coherence tomography (SD-OCT).
Methods
Forty eyes from 20 healthy, phakic individuals with open angles underwent anterior segment OCT imaging using Zeiss Cirrus SD-OCT. For each eye, inferior angle 5-line raster scans were acquired under 3 distinct pupillary states: 1) pupil constricted under standard room lighting, 2) physiologic mydriasis in a darkened room, and 3) after pharmacologic mydriasis. The inferior angle Schwalbe’s line-angle opening distance (SL-AOD) and the Schwalbe’s line-trabecular-iris-space area (SL-TISA) were computed for each eye and pupillary condition by masked, certified Reading Center graders using customized grading software.
Results
The mean age of participants was 32.3±7.4 years. Pupil diameter was 4.00±0.81 mm increasing to 5.27±0.77 mm (p<0.001) in the darkened room examinations and to 6.54±0.76 mm (p<0.001) after pharmacologic dilation. SL-AOD and SL-TISA under pupillary constriction to room light were 0.87±0.31mm and 0.33±0.14 mm2, respectively; decreased to 0.75±0.29 mm (p<0.01) and 0.29±0.13 mm2 (p<0.01), respectively under physiologic mydriasis; and increased to 0.90±0.38 mm (p<0.01) and 0.34±0.17mm2 (p=0.06) under pharmacologic mydriasis compared to baseline.
Conclusion
Using SD-OCT imaging, pharmacologic mydriasis yielded the widest angle opening (presumably from shifting the iris-lens diaphragm posteriorly), whereas physiologic mydriasis yielded the most angle narrowing in normal individuals with open iridocorneal angles.