Effect of Contact Lens Power on Optic Disc Parameters Measured with Optical Coherence Tomography

Purpose: To investigate the effect of spherical contact lens (CL) power on optical coherence tomography (OCT) measurements of optic nerve head (ONH) parameters in healthy subjects. Methods: Fifteen subjects without ocular disease underwent ONH analysis using OCT. Measurements were obtained without and with soft CL of different spherical powers (-10 diopters (D), -4 D, +4 D, +10 D). The following parameters were measured and statistically analyzed: vertical disc and cup diameters; cup area, disc area, rim area; area cup-to-disc (C/D) ratio, as well as horizontal and vertical C/D ratio. Results: Subject age was 30.5 +/- 3.2 years (mean +/- SD). Eight right and 7 left eyes were studied. Mean refractive error (spherical equivalent) was -3.9 +/- 4.7 D. Without CL, median (first, third quartiles) vertical disc and cup diameters were 1.83 (1.69, 1.96) mm and 0.74 (0.58, 1.11) mm, respectively. Cup area was 0.72 (0.56, 1.17) mm(2), disc area was 2.30 (2.10, 2.72) mm(2), and rim area was 1.49 (1.23, 1.75) mm(2). Area C/D ratio was 0.35 (0.23, 0.46), horizontal C/D ratio was 0.58 (0.49, 0.73), and vertical C/D ratio was 0.56 (0.47, 0.63). There was no systematic effect of CL power on these parameters. Conclusions: Spherical CL power does not appear to affect measurements of ONH parameters using OCT.