Optical coherence tomography (OCT) is a high resolution, non-invasive imaging technology that employs light to create detailed images of the body. In medicine, OCT is most widely used in ophthalmology to create high resolution images of the cornea and the retina.
The group index of cornea, rather than phase refractive index, is required for thickness calculations with optical coherence tomography (OCT). Recent advances with high speed OCT at 1.3 µm make index measurement at this wavelength of great interest. Group indices of 3 human eye bank corneas were measured in vitro using optical low-coherence reflectometry. Measurements were made in a calibrated cuvette filled with a preservation medium to maintain proper corneal hydration. Group indices were calculated from the optical path lengths measured. The corneal group index was 1.389 ± 0.004 (average ± standard deviation).
The rising popularity of refractive surgery presents a dilemma for eye banks. Surgically modified corneas, which are difficult to identify and non-transplantable, are being harvested and undergoing transplantation. We construct an OCT system specifically for examination of eye bank donor corneas. Analysis of 24 normal corneas and 5 LASIK corneas show that anterior corneal curvature is the best parameter for discriminating between normal corneas and LASIK corneas (p = 0.023).
Glaucoma is the second leading cause of blindness in the world today. Early detection is essential to prevent visual loss. The retinal nerve fiber layer (RNFL), which degenerates in glaucoma, reflects light preferentially in certain directions and this directional reflectance can potentially provide a signal of its health. We demonstrate the use of an OCT variant that probes multiple incidence angles to examine the fixed rat retinal nerve fiber layer (RNFL). By doing so, we demonstrate the feasibility of measuring the directional reflectance of the rat RNFL in vitro using OCT. This is the first step towards developing a clinical system that can be used to compare normal eyes and glaucomatous eyes.