Nimesh Patel

Nimesh Patel
University of Houston | U of H, UH · University Eye Institute

Doctor of Philosophy

About

42
Publications
5,269
Reads
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852
Citations
Additional affiliations
September 2018 - present
University of Houston
Position
  • Professor (Associate)
September 2012 - August 2018
University of Houston
Position
  • Professor (Assistant)
July 2003 - July 2007
Northeastern State University
Position
  • Professor (Assistant)
Education
August 2007 - May 2012
University of Houston
Field of study
  • Vision Science
July 2002 - June 2003
Northeastern State University
Field of study
  • Family Practice Residency - Optometry
August 1998 - June 2002
Southern College of Optometry
Field of study
  • Optometry

Publications

Publications (42)
Article
Full-text available
Electroretinograms (ERGs) are mass potentials with a retinal origin that can be measured non-invasively. They can provide information about the physiology of the retina. Often, ERGs are measured to flashes that are highly unnatural stimuli. To obtain more information about the physiology of the retina, we measured ERGs with temporal white noise (TW...
Article
Full-text available
Purpose: There is conflicting evidence regarding whether a loss of radial peripapillary capillaries (RPCs) precedes neuronal loss in glaucoma. We examined the time course of in vivo changes in RPCs, optic nerve head (ONH) structure, and retinal nerve fiber layer thickness (RNFLT) in experimental glaucoma (EG). Methods: Spectral domain optical co...
Preprint
Full-text available
Purpose There is conflicting evidence as to whether a loss of radial peripapillary capillaries (RPCs) precedes neuronal loss in glaucoma. We examined the time-course of in vivo changes in RPCs, optic nerve head (ONH) structure, and retinal nerve fiber layer thickness (RNFLT) in experimental glaucoma (EG). Methods Spectral domain optical coherence...
Article
Importance Long-duration spaceflight induces structural changes in the brain and eye. Identification of an association between cerebral and ocular changes could help determine if there are common or independent causes and inform targeted prevention strategies or treatments. Objective To determine if there is an association between quantitative cha...
Article
Importance While 6-month data are available regarding spaceflight-associated neuro-ocular syndrome, manned missions for 1 year and beyond are planned, warranting evaluation for spaceflight-associated neuro-ocular syndrome beyond 6 months. Objective To determine if the manifestation of spaceflight-associated neuro-ocular syndrome worsens during Int...
Article
Serial block-face scanning electron microscopy (SBF-SEM) allows for the collection of hundreds to thousands of serially-registered ultrastructural images, offering an unprecedented three-dimensional view of tissue microanatomy. While SBF-SEM has seen an exponential increase in use in recent years, technical aspects such as proper tissue preparation...
Article
Purpose The macaque retina is often used as a model for the human retina. However, there are only a handful of direct in vivo comparisons of the retinal physiology in humans and macaques. In the current study, ERG responses to luminance, L-cone isolating and M-cone isolating stimuli with sinusoidal, sawtooth and square wave temporal profiles were m...
Article
Full-text available
Purpose: Loss of ganglion cell inner plexiform layer (GCIPL) and visual sensitivity in the macula region are known to occur at all stages of glaucoma. While both are dependent on the underlying retinal ganglion cells (RGCs), the relationship between structure and function is modest. We hypothesize that the imprecise relationship is due to a lack o...
Article
Full-text available
Purpose: The purpose of this study was to determine changes in optic nerve head (ONH) morphology in seated and 6° head-down tilt (HDT) postures over a 12-hour period. Methods: Thirty eyes of 30 healthy human subjects (15 females) were included. Composite radial and circular optical coherence tomography (OCT) scans centered on the ONH, intraocula...
Article
Guinea pigs are a common model of human ocular conditions; however, their visual function has not been fully characterized. The purpose of this study was to determine the contributions of retinal ganglion cells to structural and functional measures in guinea pigs. Healthy adult guinea pigs (n = 12) underwent unilateral optic nerve crush. Retinal st...
Article
Significance: Scleral lenses (SLs) are increasing in scope, and understanding their ocular health impact is imperative. The unique fit of an SL raises concern that the landing zone causes compression of conjunctival tissue that can lead to resistance of aqueous humor outflow and increased intraocular pressure (IOP). Purpose: This study aimed to...
Article
Full-text available
Purpose: Adaptive optics scanning laser ophthalmoscope (AOSLO) capillary perfusion images can possess large variations in contrast, intensity, and background signal, thereby limiting the use of global or adaptive thresholding techniques for automatic segmentation. We sought to develop an automated approach to segment perfused capillaries in AOSLO...
Article
Importance During long-duration spaceflights, nearly all astronauts exhibit some change in ocular structure within the spectrum of spaceflight-associated neuro-ocular syndrome. Objective To quantitatively determine in a prospective study whether changes in ocular structures hypothesized to be associated with the development of spaceflight-associat...
Article
Optic nerve head (ONH) neuroretinal rim thickness, quantified as minimum rim width (BMO-MRW), is a sensitive measure for assessing early glaucomatous disease. The BMO-MRW is sensitive to transient fluctuations in intraocular pressure (IOP), but the time course over which BMO-MRW decreases and recovers with changes in IOP remains unknown. The goal o...
Article
Importance Optic disc edema develops in astronauts during long-duration spaceflight and is a risk for all future astronauts during spaceflight. Having a ground-based analogue of weightlessness that reproduces critical features of spaceflight-associated neuro-ocular syndrome will facilitate understanding, preventing, and/or treating this syndrome....
Article
Purpose: Ocular diurnal rhythms have been implicated in myopia, glaucoma, diabetes, and other ocular pathologies. Ocular rhythms have been well described in adults; however, they have not yet been fully examined in children. The goal of this study was to investigate ocular and systemic diurnal rhythms over 24 h in children. Methods: Subjects, ag...
Article
Full-text available
Significance: Causes of papilledema can be life-threatening; however, distinguishing papilledema from pseudopapilledema is often challenging. The conventional optical coherence tomography (OCT) scan for assessing the optic nerve often fails to detect mild papilledema. Our study suggests that parameters derived from volumetric OCT scans can provide...
Article
Full-text available
Purpose: To investigate diurnal variations in anterior and posterior segment biometry and assess differences between emmetropic and myopic adults. Methods: Healthy subjects (n = 42, 23-41 years old) underwent biometry and spectral-domain optical coherence tomography imaging (SD-OCT) every 4 hours for 24 hours. Subjects were in darkness from 11:0...
Article
Ocular dominance plasticity has been extensively studied in various mammalian species. While robust ocular dominance (OD) shifts are typically observed after monocular eyelid suture, relatively poor OD plasticity is observed for early eye removal or after tetrodotoxin (TTX) injections in mice. Hence, abnormal binocular signal interactions in the vi...
Article
Intraocular pressure (IOP) is an important risk factor for glaucoma, and the response of the ONH and surrounding tissues to elevated IOP are often investigated to better understand pathophysiology. In vivo structure including that of the optic nerve head (ONH) and surrounding tissue of the eye are often assessed using optical coherence tomography (...
Article
Significance: For glaucoma patients, high intraocular pressure (IOP) is a risk factor for progressive neuropathy. Similarly, animal models used to study the disease are based on an experimental elevation of IOP. Thus, accurate IOP measurements are important in characterizing experimental models and resulting effects. Purpose: The purpose of the...
Article
Full-text available
Purpose: Previous studies suggest that the adenosine receptor antagonist, 7-methylxanthine (7-MX), retards myopia progression. Our aim was to determine whether 7-MX alters the compensating refractive changes produced by defocus in rhesus monkeys. Methods: Starting at age 3 weeks, monkeys were reared with -3 diopter (D; n = 10; 7-MX -3D/pl) or +3...
Article
Importance After long-duration spaceflight, morphological changes in the optic nerve head (ONH) and surrounding tissues have been reported. Objective To develop methods to quantify ONH and surrounding tissue changes using preflight and postflight optical coherence tomographic scans of the ONH region. Design, Setting, and Participants Two separate...
Article
Changes in the foveal anatomy during infancy are an important component in early development of spatial vision. The present longitudinal study in rhesus monkeys was undertaken to characterize the postnatal maturation of the fovea. Starting at four weeks after birth, the retinas of the left eyes of sixteen infant monkeys were imaged using spectral d...
Article
Background: Several ophthalmic findings including optic disc swelling, globe flattening and choroidal folds have been observed in astronauts following long-duration space flight. The authors now report asymmetric choroidal expansion, disc swelling and optic disc morphologic changes in a 45-year-old astronaut which occurred during long-duration spa...
Article
Full-text available
The lamina cribrosa likely plays an important role in retinal ganglion cell axon injury in glaucoma. We sought to (1) better understand optic nerve head (ONH) structure and anterior lamina cribrosa surface (ALCS) microarchitecture between fellow eyes of living, normal non-human primates and (2) characterize the time-course of in vivo structural cha...
Article
Full-text available
Optical coherence tomography is an imaging technique using low coherence light sources to produce high-resolution cross-sectional images. This article reviews pertinent anatomy and various pathologies causing optic atrophy (eg, compressive, infiltrating, demyelinating) versus optic nerve swelling (from increased intracranial pressure known as papil...
Article
To evaluate whether quantity of choroidal tissue directly adjacent to the optic nerve differs between eyes with and without glaucoma and whether beta-zone parapapillary atrophy influences this relationship. Prospective cohort study. Subjects were enrolled in a longitudinal, observational study at our institution. We studied one eye of 63 primary op...
Article
Full-text available
Purpose: The purpose of this study was to determine the relationship between optical coherence tomography (OCT) measures of retinal nerve fiber layer (RNFL) and neuroretinal rim (NRR) in a nonhuman primate experimental glaucoma model, and in a population of clinical patients. Methods: For nonhuman primates, normative data were collected from 44...
Article
Full-text available
Purpose: Optical coherence tomography (OCT) measures of the retinal nerve fiber layer (RNFL) thickness and neuroretinal rim (NRR) parameters are often used as a surrogate for retinal ganglion cell content. The purpose of this study was to investigate the relationship between these morphological measures and the aging effects on these structures....
Article
Full-text available
Purpose: We investigated relations between macular retinal ganglion cell plus inner plexiform layer (RGC+IPL) thickness and macular retinal function revealed by multifocal electroretinonography (mfERG) in a nonhuman primate model of experimental glaucoma. Methods: Retinal ganglion cell (RGC) structure and function were followed with spectral-dom...
Article
The multifocal electroretinogram (mfERG) is a useful tool for objectively assessing localized functional changes at early stages of glaucoma, and as the disease progresses. The photopic negative response (PhNR) of the light-adapted full field ERG has been found to be reduced in glaucoma. We assessed the local loss of inner retinal function as refle...
Article
Purpose: To investigate the expression and/or function of toll-like receptors (TLRs) and antimicrobial peptides (AMPs) in dry eye inflammation. Methods: Experimental dry eye (EDE) was induced in C57BL/6 mice and TLR mRNA and protein expression were determined at the ocular surface and lacrimal gland. TLR agonist cocktail was applied to the ocula...
Article
Full-text available
Purpose: Retinal nerve fiber layer (RNFL) thickness measures with spectral domain-optical coherence tomography (SD-OCT) provide important information on the health of the optic nerve. As with most retinal imaging technologies, ocular magnification characteristics of the eye must be considered for accurate analysis. While effects of axial length ha...
Article
An assessment of the retinal nerve fiber layer (RNFL) provides important information on the health of the optic nerve. There are several non-invasive technologies, including spectral domain optical coherence tomography (SD OCT), that can be used for in vivo imaging and quantification of the RNFL, but often there is disagreement in RNFL thickness be...
Article
The eyes of newborn mice are relatively underdeveloped and the lids remain closed for the first 2 weeks after birth. There after the eyes undergo a period of rapid growth for several weeks. Eventually the eyes reach an age at which many ocular structures stabilize for the remainder of the animal's life, or for others, growth is significantly slowed...
Article
Full-text available
The ability to consistently resolve lamina cribrosa pores in vivo has applications in the study of optic nerve head and retinal disease mechanisms. Repeatability was assessed in imaging laminar pores in normal living eyes with a confocal adaptive optics scanning laser ophthalmoscope (AOSLO). Reflectance images (840 nm) of the anterior lamina cribro...
Article
Full-text available
An evaluation of the retinal nerve fiber layer (RNFL) provides important information on the health of the optic nerve. Standard measurements of the RNFL consider only thickness, but an accurate assessment should also consider axial length, size of the optic nerve head (ONH), blood vessel contribution, and distance of the scan from the ONH margin. I...
Article
Full-text available
To study relationships between glaucoma-sensitive components identified with frequency-domain analysis of global-flash multifocal electroretinogram (mfERG), regional retinal nerve fiber layer thickness (RNFLT), and local visual field sensitivity (VS). Eleven macaque monkeys, including four controls and seven with unilateral laser-induced trabecular...
Article
The electron microscope is a powerful tool for understanding the three-dimensional (3-D) ultrastructure of cells and tissues. While computer-aided electron tomography can be used to reconstruct 3-D volumes of individual thick (≤ 1 µm) tissue sections, thicker tissue samples require serial sections. The collection of large numbers of serial sections...