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From the Storm Eye Institute, Medical University of South Carolina, Department of Ophthalmology, Charleston, South Carolina (APL, SDG, KMR, ERZ, DMT, GOW); and the Department of Bioengineering, College of Engineering and Science, Clemson University, Clemson, South Carolina (GOW).
Supported by a Research to Prevent Blindness grant to Storm Eye Institute; building construction support via NIH/NCRR C06 RR-015455; South Carolina Clinical & Translational Research Institute via NIH/NCRR TL1 RR029881 and TL1 TR000061 (APL); NIH Medical Scientist Training Program Grant T32 GM08716 (APL); and Department of Education Graduate Assistantship in Areas of National Need P200A040143 (APL).
Dr. Waring is a consultant to Acufocus, Inc., distributor of OQAS II and Visiometrics, manufacturer of the instrument. The remaining authors have no financial or proprietary interest in the materials presented herein.
Multiple imaging technologies have been proposed and used to evaluate the cornea to more accurately detect the onset of keratoconus. Corneal topography and tomography have been used to diagnose keratoconus by measuring the curvature, anterior and posterior elevation of the cornea, minimal corneal thickness, anterior chamber angle, corneal volume, and anterior chamber depth. 1,2 Anterior segment optical coherence tomography (OCT) has detected corneal thinning in patients with keratoconus with similar sensitivity and specificity to corneal topography, with significant changes observed in epithelial thickness profile. 3-5 Interestingly, OCT of the retina has been shown to reveal small increases (approximately 10 [micro]m) in macular thickness in keratoconic eyes. 6 Studies have shown posterior corneal measurement by the Scheimpflug camera to dispute the theoretical properties of the posterior cornea, cautioning its use alone in diagnosing a keratoconic eye. 7,8 The biomechanical parameters of corneal hysteresis and the corneal resistance factor have been shown to significantly decrease following LASIK or with the diagnosis of keratoconus. 9-11
The purpose of this study was to explore the role of double-pass retina point imaging in keratoconus and to determine whether qualitative and quantitative measurements from this technique can be used to aid in its diagnosis and staging of severity.
Patients and Methods
All research was approved by the Medical University of South Carolina Institutional Review Board and informed consent was obtained from participants. A series of patients with keratoconus evaluated prior to any ocular surgery and normal eyes underwent double-pass retina point imaging analysis in...