A Prospective Study Examining Contact Lens Wear, Refractive Error, and Optical Coherence Tomography Retinal Nerve Fiber Layer Measurements Marie Brenner MS4, Pooja B Jamnadas MD, Peter Russo OD, Shuchi Patel MD Loyola University Medical Center, Department of Ophthalmology, Maywood IL References Introduction Conclusions Retinal nerve fiber layer (RNFL) measurements are often used to aid ophthalmologists in the diagnosis and management of glaucoma. One of the challenges in measuring retinal nerve fiber layer thickness is obtaining good quality scans with accurate measurements. Our study serves to report the effects of contact lenses wear on RNFL measurements. Furthermore, we sought to determine if the degree of refractive error impacts RNFL measurements or Q values with contact lens wear. We studied patients with both soft and rigid gas permeable lenses. At lower refractive errors, better quality studies are obtained without contact lenses in place Higher refractive errors which are corrected with contact lenses may lead to improved quality Distortion due to the contact lenses may be negated when refractive error exceeds diopters Further studies are needed with larger cohorts in order to create an appropriately powered trial which can provide conclusive information Ongoing data collection and statistical analysis pending 1. Budenz DL, Change RT, Huang X, Knighton RW, Tielsh JM. Reproducibility of Retinal Nerve Fiber Thickness Measurements Using the Status OCT in Normal and Glaucomatous Eyes. Investigative Ophthalmology & Visual Schience. 2005; 46(7): Fujimoto JG. Optical coherence tomography for ultrahigh resolution in vivoimaging. Nature Biotechnology. 2003; 21(11): Youm DJ, Kim JM, Park KH, Choi CY. The Effect of Soft Contact Lenses During the Measurement of Retinal Nerve Fiber Layer Thickness Using Optical Coherence Tomography. Current Eye Research 2009; 34: Abstract Purpose: The purpose of this study is to determine if statistically significant differences exist between retinal nerve fiber layer (RNFL) measurements and quality (measured in Q value) of optical coherence tomography (OCT) in patients with and without contact lenses. We also aimed to determine if higher refractive errors made a larger effect on the RNFL and Q value measurements. We examined soft and rigid gas permeable lenses. Methods: After obtaining IRB approval and consent, patients in the Loyola eye clinic had their RNFL measured with and without contact lenses using the Spectralis OCT (Heidelberg Engineering USA). The patient's refractive error, RNFL, and Q value were recorded. A paired t test was used comparing the average RNFL and Q value with and without contact lenses. A subgroup analysis was done looking at patients with refractive errors lower than -5.0 diopters, and equal to or above -5.0 diopters. For patients with astigmatism, the spherical equivalence was used. Subgroup analysis was also done comparing RGP lenses and soft contact lenses. Results: No statistically significant difference is present in RNFL measurments and OCT quality with or without contact lens wear overall. Subgroup analysis found no statistically significant difference in RNFL. The difference in Q value was not significant in subjects with higher refractive errors. Patients with a lower refractive error with soft contact lenses had significantly better quality studies without contact lenses. Patients with RGP lenses had significantly better quality studies without contact lenses. Gross examination of the study images does show more clear images in patients with higher refractive errors when contacts are in. Although not significant, average Q values are higher in patients with contact lenses with refractive errors above Conclusions: We conclude that at lower refractive errors, better quality studies are obtained without contact lenses. However, we hypothesize that with higher refractive errors, correcting refractive error with contact lenses provides an improved quality which begins to negate the distortion caused by the contact lens itself. Therefore, additional studies that include more patients with higher refractive errors are needed to see if a larger n will allow for results to reach statistical significance. Acknowledgements: The Illinois Society for the Prevention of Blindness The Richard A. Perritt Charitable Foundation Methods IRB approved, prospective case control study 9 patients presented to the Loyola eye clinic for routine examination Patients were provided appropriate informed consent and were aware of the risks and benefits of participation Patients underwent Spectralis OCT (Heidelberg Engineering USA) testing with and without their daily contact lenses in place We studied refractive error, RNFL, Q value with and without contact lenses in place Subgroup analysis was conducted with chi square analysis analyzing whether degree of refractive error impacted pertinent variables Patients with astigmatism were included using spherical equivalence Subgroup analysis was also performed on whether rigid gas permeable or soft contact lenses had an impact on pertinent variables Gross Examination: Better Image Quality with Contact Lens Results Contact LensNo Contact Lenses Patients with a lower refractive error had significantly better quality studies without contact lenses. Patients with rigid gas permeable lenses had better quality studies without contact lenses. Although not significant, average Q values are higher in patients with contact lenses with refractive errors above