Contrast Sensitivity in Patients With Emmetropic Presbyopia Before and After Small-Aperture Inlay Implantation

PURPOSE: To develop a normative contrast sensitivity function and examine the postoperative contrast sensitivity outcomes for emmetropic patients with presbyopia implanted with a KAMRA intracorneal inlay (AcuFocus Inc., Irvine, CA) in their non-dominant eyes. METHODS: A prospective, non-randomized, multicenter clinical trial was conducted on 507 patients between 45 and 60 years of age who were monocularly implanted with the KAMRA inlay. A predetermined subgroup of 335 patients in the contrast sensitivity substudy were measured preoperatively and postoperatively with the Functional Acuity Contrast Test (FACT) chart in the Optec 6500 Vision Tester (Stereo Optical Co., Chicago, IL) under monocular and binocular, photopic and mesopic without glare, and binocular mesopic with glare conditions each over four spatial frequencies (3, 6, 12, and 18 cycles per degree for photopic conditions and 1.5, 3, 6, and 12 cycles per degree for mesopic conditions). Normative ranges were developed using 1.96 standard deviations from the preoperative mean logCS (log(10) unit of contrast sensitivity). RESULTS: The preoperative contrast sensitivity measurements were used to develop the normative contrast sensitivity curves. Postoperatively, contrast sensitivity was stable both monocularly and binocularly and average contrast sensitivity remained within the normative ranges. Postoperative contrast sensitivity was mildly reduced monocularly but not binocularly, and the ratio of area under logCS function comparing postoperative to preoperative values was above 90% for all but one condition. CONCLUSIONS: Normative contrast sensitivity curves for a presbyopic population are established to provide a referent in the investigation of the impact of other presbyopia-correcting ophthalmic procedures on contrast sensitivity.