Gas-Permeable Contact Lenses and Water Exposure: Practices and Perceptions.

SIGNIFICANCE: This study provides insight into the current recommendations, clinical behaviors, and risk assessments of eye care professionals on the topic of rigid contact lens exposure to tap water. This knowledge may motivate professional organizations to develop initiatives to educate eye care professionals on the dangers of contact lens exposure to water. PURPOSE: The purpose of this study was to investigate the practice patterns and risk perceptions of eye care professionals regarding gas-permeable contact lens exposure to tap water. METHODS: A branched-logic survey was started by 320 clinicians, vision scientists, and industry personnel and was fully completed by 272 participants. The survey queried participants about their current practices, recommendations, and perceptions of risk regarding exposure of gas-permeable contact lenses to tap water. RESULTS: Of those who prescribe gas-permeable contact lenses, 57.4% reported rinsing lenses with tap water, whereas only 32.7% reported engaging in this same behavior in front of patients. Of those who reported never rinsing lenses with tap water, 85.6% indicated that rinsing lenses with water increases infection risk, whereas 52.1% of those who rinse lenses with water reported the same perceived risk (P < .001). Of all participants, 60% indicated that wearing contact lenses while showering increases infection risk, and 50.2% of all participants advised patients to avoid this behavior. CONCLUSIONS: A discrepancy exists between perceptions of risk concerning exposure of contact lenses to water and both clinical practices and patient education provided by professionals.

Foveal Curvature and Asymmetry Assessed Using Optical Coherence Tomography.

PURPOSE: The aims of this study were to use cross-sectional optical coherence tomography imaging and custom curve fitting software to evaluate and model the foveal curvature as a spherical surface and to compare the radius of curvature in the horizontal and vertical meridians and test the sensitivity of this technique to anticipated meridional differences. METHODS: Six 30-degree foveal-centered radial optical coherence tomography cross-section scans were acquired in the right eye of 20 clinically normal subjects. Cross sections were manually segmented, and custom curve fitting software was used to determine foveal pit radius of curvature using the central 500, 1000, and 1500 µm of the foveal contour. Radius of curvature was compared across different fitting distances. Root mean square error was used to determine goodness of fit. The radius of curvature was compared between the horizontal and vertical meridians for each fitting distance. RESULTS: There radius of curvature was significantly different when comparing each of the three fitting distances (P < .01 for each comparison). The average radii of curvature were 970 µm (95% confidence interval [CI], 913 to 1028 µm), 1386 µm (95% CI, 1339 to 1439 µm), and 2121 µm (95% CI, 2066 to 2183) for the 500-, 1000-, and 1500-µm fitting distances, respectively. Root mean square error was also significantly different when comparing each fitting distance (P < .01 for each comparison). The average root mean square errors were 2.48 µm (95% CI, 2.41 to 2.53 µm), 6.22 µm (95% CI, 5.77 to 6.60 µm), and 13.82 µm (95% CI, 12.93 to 14.58 µm) for the 500-, 1000-, and 1500-µm fitting distances, respectively. The radius of curvature between the horizontal and vertical meridian radii was statistically different only in the 1000- and 1500-µm fitting distances (P < .01 for each), with the horizontal meridian being flatter than the vertical. CONCLUSIONS: The foveal contour can be modeled as a sphere with low curve fitting error over a limited distance and capable of detecting subtle foveal contour differences between meridians.

Fixational errors for two-dimensional tracking tasks with black and complex backgrounds.

INTRODUCTION: In low-level flight, pilots must track objects against an array of background objects. The purpose of this study was to determine what influence the objects in a flight simulator background have on catch-up saccades and overall fixational errors during head-free ocular tracking. METHODS: Two experiments were performed. In Experiment 1, subjects tracked a two-dimensional target consisting of the sum of five sinusoids (frequencies 0.30-1.25 Hz) horizontally and six sinusoids (frequencies 0.24-1.25 Hz) vertically in three background conditions. In one condition, the background was black, in another condition the projected background was the Microsoft screensaver "Starfield Simulation," and in another condition the background was that seen from a helicopter during a flight recorded in the Microsoft 2000 Flight Simulator software. Experiment 2 was the same as Experiment 1, except the frequency of each target sinusoid was doubled. RESULTS: Radial fixational errors were calculated. In Experiment 1, the mean errors were 3.73 +/- 0.57 degrees (black background), 3.75 +/- 0.57 degrees (starfield simulation), and 3.87 +/- 0.70 degrees (flight simulator). These values were not significantly different. In Experiment 2, the mean errors were 7.04 +/- 0.54degrees (black background), 7.04 +/- 0.38 degrees (starfield simulation), and 8.15 +/- 0.96 degrees (flight simulator). These values were significantly different. DISCUSSION: The distractors of the starfield simulation and flight simulator background did not influence catch-up saccades (Experiment 1). In Experiment 2, the flight simulator background increased the mean fixational errors most likely by drawing attention from the target.