The primary objective of this career training proposal is the provide an academic optometrist with the didactic and laboratory training necessary to be an independent researcher. The objective of this project is to improve the precision and accuracy of in vivo measures of the retinal nerve fiber layer (RNFL), a surrogate for the ganglion cell content within the eye, using customized scans for the early detection or progression of glaucoma. Glaucoma is a group of diseases that can lead to irreversible blindness if left untreated. It is estimated that by the year 2030, 37 million individuals worldwide will be blinded by this disease, with 82% of these individuals being over the age of 50. In the United States, glaucoma is a significant public health problem, affecting 2.2 million individuals, and being a leading cause of blindness. Having an elusive cause, the diagnosis or progression of glaucoma is often made by direct assessment of the optic nerve, evaluating the integrity of the retinal nerve fiber layer (RNFL) and measuring the sensitivity of the visual field. Advances in imaging technology allow for an objective assessment of the retina and optic nerve. Specifically, spectral domain optical coherence tomography (SD-OCT) allow for up to 75m axial resolution. A 12 degree circular scan centered on the optic nerve is often used clinically for measuring the thickness of the RNFL. For an accurate and precise assessment of the RNFL, it is important to account for factors such as ocular magnification and the contribution of the non-neuronal content. Using non-invasive methodologies to measure ocular biometry, ocular magnification can be computed. Although glial tissue and small retinal vessels cannot be visualized in SD-OCT scans, the major retinal vessels cast shadows on the underlying tissues, and can be accounted for. The goal of the project is to investigate RNFL thickness and area measures after consideration of ocular magnification and compensation for major retinal vasculature. In particular, these methodologies will be used to 1) investigate changes in the thickness and cross sectional area of the RNFL with glaucoma disease progression in the non-human primate model;2) investigate RNFL measures and the vascular contribution to the RNFL that occur with normal ageing;3) investigate RNFL measures and the functional relationship to visual fields in glaucoma patients. Clinical implementation of this technology will improve the diagnostic accuracy and treatment outcomes of patients with glaucoma.

Public Health Relevance

Glaucoma is a significant public health problem affecting 2.2 million individuals in the United States, of which 120,000 are legally blind. The treatment and management of the disease is estimated to have a direct financial burden of $2.9 billion, with the care of more advanced cases costing up to four times those of early stages. The goal of this project is to improve the accuracy and precision of in vivo measures of the stage of optic neuropathy to aid in the early diagnosis of this visually devastating disease.

National Institute of Health (NIH)
National Eye Institute (NEI)
Mentored Patient-Oriented Research Career Development Award (K23)
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Special Emphasis Panel (ZEY1-VSN (11))
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Agarwal, Neeraj
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University of Houston
Schools of Optometry/Ophthalmol
United States
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Takahata, Toru; Patel, Nimesh B; Balaram, Pooja et al. (2018) Long-term histological changes in the macaque primary visual cortex and the lateral geniculate nucleus after monocular deprivation produced by early restricted retinal lesions and diffuser induced form deprivation. J Comp Neurol 526:2955-2972
Patel, Nimesh; McAllister, Faith; Pardon, Laura et al. (2018) The effects of graded intraocular pressure challenge on the optic nerve head. Exp Eye Res 169:79-90
McAllister, Faith; Harwerth, Ronald; Patel, Nimesh (2018) Assessing the True Intraocular Pressure in the Non-human Primate. Optom Vis Sci 95:113-119
Patel, Nimesh B; Hung, Li-Fang; Harwerth, Ronald S (2017) Postnatal maturation of the fovea in Macaca mulatta using optical coherence tomography. Exp Eye Res 164:8-21
Ivers, Kevin M; Sredar, Nripun; Patel, Nimesh B et al. (2015) In Vivo Changes in Lamina Cribrosa Microarchitecture and Optic Nerve Head Structure in Early Experimental Glaucoma. PLoS One 10:e0134223
Sullivan-Mee, Michael; Patel, Nimesh B; Pensyl, Denise et al. (2015) Relationship Between Juxtapapillary Choroidal Volume and Beta-Zone Parapapillary Atrophy in Eyes With and Without Primary Open-Angle Glaucoma. Am J Ophthalmol 160:637-47.e1
Patel, Nimesh B; Sullivan-Mee, Michael; Harwerth, Ronald S (2014) The relationship between retinal nerve fiber layer thickness and optic nerve head neuroretinal rim tissue in glaucoma. Invest Ophthalmol Vis Sci 55:6802-16
Patel, Nimesh B; Lim, Mimi; Gajjar, Avni et al. (2014) Age-associated changes in the retinal nerve fiber layer and optic nerve head. Invest Ophthalmol Vis Sci 55:5134-43
Luo, Xunda; Patel, Nimesh B; Rajagopalan, Lakshmi P et al. (2014) Relation between macular retinal ganglion cell/inner plexiform layer thickness and multifocal electroretinogram measures in experimental glaucoma. Invest Ophthalmol Vis Sci 55:4512-24
Patel, Nimesh B; Garcia, Brenda; Harwerth, Ronald S (2012) Influence of anterior segment power on the scan path and RNFL thickness using SD-OCT. Invest Ophthalmol Vis Sci 53:5788-98

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