The short-term goal of this research is to extend the understanding of the relationship between structural and functional measurements used in glaucoma management. This involves the collection of data from perimetry and optical coherence tomography in glaucoma subjects, comparison of perimetry to contrast sensitivity in glaucoma subjects, and analysis of retinal nerve fiber layer in glaucomatous monkeys. Using relationships derived from experimental glaucoma in monkeys (Harwerth, personal communication, unpublished data) ganglion cell densities will be predicted by visual field sensitivity data and by nerve fiber layer thickness measures from optical coherence tomographey (OCT) for human glaucoma patients. These estimates will be compared across corresponding regions in order to demonstrate agreement. Standard perimetry in glaucoma management uses a white stimulus to detect thresholds, but other stimulus parameters have been shown to be more sensitivite to early damage. By using Gabor patches varied in size and contrast, one can obtain contrast sensitivity functions (CSF) for a variety of locations much like standard perimetry. Experiments in glaucomatous monkeys have shown a reduction in the contrast sensitivity functions for select locations prior to detection of loss with the standard perimetry stimulus (Harwerth, personal communication, unpublished data). Human subjects with glaucoma will be tested with both forms of perimetry in order to compare the interaction of glaucoma with the two different stimuli. Retina tissue from glaucomatous monkeys with varying amounts of glaucomatous damage will be'sectioned and stained for imaging using a confocal microscopy. Actual thickness of the nerve fiber layer will be compared to pre-mortem measurements of the nerve fiber layer taken with OCT. Characteristics of axons (size and density) will also be evaluated in normal and diseased monkey eyes with confocal imaging. Glaucoma continues to be one of the leading causes of blindness in the United States, and perimetry and imaging play a vital role in diagnosis and management of the disease. This research will attempt to establish a structure-function relationship between these two instruments, and may influence the way that current information obtained with perimetry and tomography is interpreted and used in patient management. My long-term goals include applying these findings and experiences to future glaucoma research.
| Wheat, Joe L; Rangaswamy, Nalini V; Harwerth, Ronald S (2012) Correlating RNFL thickness by OCT with perimetric sensitivity in glaucoma patients. J Glaucoma 21:95-101 |
| Patel, Nimesh B; Wheat, Joe L; Rodriguez, Aldon et al. (2012) Agreement between retinal nerve fiber layer measures from Spectralis and Cirrus spectral domain OCT. Optom Vis Sci 89:E652-66 |
| Patel, Nimesh B; Luo, Xunda; Wheat, Joe L et al. (2011) Retinal nerve fiber layer assessment: area versus thickness measurements from elliptical scans centered on the optic nerve. Invest Ophthalmol Vis Sci 52:2477-89 |
| Harwerth, R S; Wheat, J L; Fredette, M J et al. (2010) Linking structure and function in glaucoma. Prog Retin Eye Res 29:249-71 |
