Search

Importance: A neurophysiologic signature of the melanopsin-mediated persistent constriction phase of the pupillary light reflex may represent a surrogate biomarker for the integrity of the retinohypothalamic tract, with potential utility for investigating alterations in homeostatic mechanisms associated with brain disorders and implications for identifying new treatments., Objective: To characterize abnormalities of retinal architecture in patients with multiple sclerosis (MS) and corresponding alterations in the melanopsin-mediated sustained pupillary constriction response., Design, Setting, and Participants: The case-control study was an experimental assessment of various stimulus-induced pupillary response characteristics and was conducted at a university clinical center for MS from September 6, 2012, to February 2015. Twenty-four patients with MS (48 eyes) and 15 individuals serving as controls (30 eyes) participated. The melanopsin-mediated, sustained pupillary constriction phase response following cessation of a blue light stimulus was compared with the photoreceptor-mediated pupillary constriction phase response following cessation of a red light stimulus. Optical coherence tomography was used to characterize the association between pupillary response characteristics and alterations in retinal architecture, specifically, the thickness of the retinal ganglion cell layer and inner plexiform layer (GCL + IPL)., Main Outcomes and Measures: Association of pupillary response characteristics with alterations in retinal architecture., Results: Of 24 patients with MS included in the analysis, 17 were women (71%); mean (SD) age was 47 (11) years. Compared with eyes from individuals with MS who had normal optical coherence tomography-derived measures of retinal GCL + IPL thickness, eyes of patients who had GCL + IPL thickness reductions to less than the first percentile exhibited a correspondingly significant attenuation of the melanopsin-mediated sustained pupillary response (mean [SD] pupillary diameter ratios at a point in time, 0.18 [0.1] vs 0.33 [0.09]; P < .001, generalized estimating equation models accounting for age and within-patient intereye correlations)., Conclusions and Relevance: In this case-control study, attenuation of the melanopsin-mediated sustained pupillary constriction response was significantly associated with thinning of the GCL + IPL sector of the retina in the eyes of patients with MS, particularly those with a history of acute optic neuritis. Melanopsin-containing ganglion cells in the retina represent, at least in part, the composition of the retinohypothalamic tract. As such, our findings may signify the ability to elucidate a putative surrogate neurophysiologic signature that correlates with a constellation of homeostatic mechanisms in both health and illness.

We have previously demonstrated that enalapril, α-lipoic acid and menhaden (fish) oil has potential as a treatment for diabetic peripheral neuropathy. In this study we sought to determine the efficacy of these treatments individually or in combination on multiple neuropathic endpoints in a high fat fed low dose streptozotocin treated mouse, a model of type 2 diabetes, following early or late intervention. Four or twelve weeks after the onset of hyperglycemia, diabetic mice were treated with enalapril, α-lipoic acid, menhaden oil or their combination for 12 weeks. Afterwards, endpoints including glucose tolerance, motor and sensory nerve conduction velocity, thermal nociception, and intraepidermal and cornea nerve fiber density was determined. Glucose clearance was impaired in diabetic mice and significantly improved only with combination treatment and early intervention. Diabetes caused steatosis, slowing of motor and sensory nerve conduction velocity, thermal hypoalgesia and reduction in intraepidermal and cornea nerve fiber density. Treating diabetic mice with enalapril, α-lipoic acid or menhaden oil partially protected diabetic mice from these deficits, whereas the combination of these three treatments was more efficacious following early or late intervention. These studies suggest that a combination therapy may be more effective for treating neural complications of type 2 diabetes., (Published by Elsevier Ltd.)

We sought to determine, with a retrospective chart review, the imaging yield for patients with clinically isolated Horner syndrome. MRI/MRA of the head and neck extending from the supraorbital ridge to T4 with fat suppression and with postcontrast images was obtained. Of 88 patients with isolated Horner syndrome who were imaged, 20% had a causative etiology on imaging. The most common cause of an isolated Horner syndrome was a carotid artery dissection. There was 1 patient with a primary malignancy found to be the causative lesion in this group, and 1 patient with spread of their known metastatic disease., (Published by Elsevier Inc.)

Glaucoma causes a decrease in peripapillary perfused capillary density on optical coherence tomography (OCT) angiography. However, other chronic optic neuropathies have not been explored with OCT angiography to see if these changes were specific to glaucoma. The authors evaluated OCT angiography in 10 patients who suffered various kinds of chronic optic neuropathies, including optic neuritis and ischaemic optic neuropathy, and found that all optic neuropathies showed a decrease in peripapillary vessel density on OCT angiography, regardless of the aetiology of the optic neuropathy. The peripapillary vessel loss on OCT angiography correlated well with the areas of retinal nerve fibre layer thinning seen on OCT.

Purpose: The purpose of this study was to evaluate a chromatic pupillometry protocol for specific functional assessment of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) in dogs., Methods: Chromatic pupillometry was tested and compared in 37 dogs in different stages of primary loss of rod, cone, and combined rod/cone and optic nerve function, and in 5 wild-type (WT) dogs. Eyes were stimulated with 1-s flashes of dim (1 cd/m2) and bright (400 cd/m2) blue light (for scotopic conditions) or bright red (400 cd/m2) light with 25-cd/m2 blue background (for photopic conditions). Canine retinal melanopsin/Opn4 was cloned, and its expression was evaluated using real-time quantitative reverse transcription-PCR and immunohistochemistry., Results: Mean ± SD percentage of pupil constriction amplitudes induced by scotopic dim blue (scDB), scotopic bright blue (scBB), and photopic bright red (phBR) lights in WT dogs were 21.3% ± 10.6%, 50.0% ± 17.5%, and 19.4% ± 7.4%, respectively. Melanopsin-mediated responses to scBB persisted for several minutes (7.7 ± 4.6 min) after stimulus offset. In dogs with inherited retinal degeneration, loss of rod function resulted in absent scDB responses, followed by decreased phBR responses with disease progression and loss of cone function. Primary loss of cone function abolished phBR responses but preserved those responses to blue light (scDB and scBB). Although melanopsin/Opn4 expression was diminished with retinal degeneration, melanopsin-expressing ipRGCs were identified for the first time in both WT and degenerated canine retinas., Conclusions: Pupil responses elicited by light stimuli of different colors and intensities allowed differential functional assessment of canine rods, cones, and ipRGCs. Chromatic pupillometry offers an effective tool for diagnosing retinal and optic nerve diseases.

Background: Optical coherence tomography (OCT) has become an important tool for diagnosing optic nerve disease. The structural details and reproducibility of OCT continues to improve with further advances in technology. However, artifacts and misinterpretation of OCT can lead to clinical misdiagnosis of diseases if they go unrecognized., Evidence Acquisition: A literature review using PubMed combined with clinical and research experience., Results: We describe the most common artifacts and errors in interpretation seen on OCT in both optic nerve and ganglion cell analyses. We provide examples of the artifacts, discuss the causes, and provide methods of detecting them. In addition, we discuss a systematic approach to OCT analysis to facilitate the recognition of artifacts and to avoid clinical misinterpretation., Conclusions: While OCT is invaluable in diagnosing optic nerve disease, we need to be cognizant of the artifacts that can occur with OCT. Failure to recognize some of these artifacts can lead to misdiagnoses and inappropriate investigations., Competing Interests: The authors report no conflicts of interest.

Previously we demonstrated that a vasopeptidase inhibitor of angiotensin converting enzyme and neutral endopeptidase (NEP), a protease that degrades vaso- and neuro-active peptides, improves neural function in diabetic rodent models. The purpose of this study was to determine whether inhibition or deletion of NEP provides protection from neuropathy caused by diabetes with an emphasis on morphology of corneal nerves as a primary endpoint. Diabetes, modeling type 2, was induced in C57Bl/6J and NEP deficient mice through a combination of a high fat diet and streptozotocin. To inhibit NEP activity, diabetic C57Bl/6J mice were treated with candoxatril using a prevention or intervention protocol. Twelve weeks after the induction of diabetes in C57Bl/6J mice, the existence of diabetic neuropathy was determined through multiple endpoints including decrease in corneal nerves in the epithelium and sub-epithelium layer. Treatment of diabetic C57Bl/6J mice with candoxatril improved diabetic peripheral neuropathy and protected corneal nerve morphology with the prevention protocol being more efficacious than intervention. Unlike C57Bl/6J, mice deficient in NEP were protected from the development of neuropathologic alterations and loss of corneal nerves upon induction of diabetes. These studies suggest that NEP contributes to the development of diabetic neuropathy and may be a treatable target., (2016 American Association of Neuropathologists, Inc. This work is written by US Government employees and is in the public domain in the US.)

Purpose: The purpose of this study was to assess whether clinically useful measures of fixation instability and eccentricity can be derived from retinal tracking data obtained during optical coherence tomography (OCT) in patients with optic neuropathy (ON) and to develop a method for relating fixation to the retinal ganglion cell complex (GCC) thickness., Methods: Twenty-nine patients with ON underwent macular volume OCT with 30 seconds of confocal scanning laser ophthalmoscope (cSLO)-based eye tracking during fixation. Kernel density estimation quantified fixation instability and fixation eccentricity from the distribution of fixation points on the retina. Preferred ganglion cell layer loci (PGCL) and their relationship to the GCC thickness map were derived, accounting for radial displacement of retinal ganglion cell soma from their corresponding cones., Results: Fixation instability was increased in ON eyes (0.21 deg2) compared with normal eyes (0.06982 deg2; P < 0.001), and fixation eccentricity was increased in ON eyes (0.48°) compared with normal eyes (0.24°; P = 0.03). Fixation instability and eccentricity each correlated moderately with logMAR acuity and were highly predictive of central visual field loss. Twenty-six of 35 ON eyes had PGCL skewed toward local maxima of the GCC thickness map. Patients with bilateral dense central scotomas had PGCL in homonymous retinal locations with respect to the fovea., Conclusions: Fixation instability and eccentricity measures obtained during cSLO-OCT assess the function of perifoveal retinal elements and predict central visual field loss in patients with ON. A model relating fixation to the GCC thickness map offers a method to assess the structure-function relationship between fixation and areas of preserved GCC in patients with ON.

Male C57BL/6J mice raised on high fat diet (HFD) become prediabetic and develop insulin resistance and sensory neuropathy. The same mice given low doses of streptozotocin are a model of type 2 diabetes (T2D), developing hyperglycemia, severe insulin resistance and diabetic peripheral neuropathy involving sensory and motor neurons. Because of suggestions that increased NAD(+) metabolism might address glycemic control and be neuroprotective, we treated prediabetic and T2D mice with nicotinamide riboside (NR) added to HFD. NR improved glucose tolerance, reduced weight gain, liver damage and the development of hepatic steatosis in prediabetic mice while protecting against sensory neuropathy. In T2D mice, NR greatly reduced non-fasting and fasting blood glucose, weight gain and hepatic steatosis while protecting against diabetic neuropathy. The neuroprotective effect of NR could not be explained by glycemic control alone. Corneal confocal microscopy was the most sensitive measure of neurodegeneration. This assay allowed detection of the protective effect of NR on small nerve structures in living mice. Quantitative metabolomics established that hepatic NADP(+) and NADPH levels were significantly degraded in prediabetes and T2D but were largely protected when mice were supplemented with NR. The data justify testing of NR in human models of obesity, T2D and associated neuropathies.

Purpose: This study aims to identify which aspects of the pupil light reflex are most influenced by rods and cones independently by analyzing pupil recordings from different mouse models of photoreceptor deficiency., Methods: One-month-old wild type (WT), rodless (Rho-/-), coneless (Cnga3-/-), or photoreceptor less (Cnga3-/-; Rho-/- or Gnat1-/-) mice were subjected to brief red and blue light stimuli of increasing intensity. To describe the initial dynamic response to light, the maximal pupillary constriction amplitudes and the derivative curve of the first 3 seconds were determined. To estimate the postillumination phase, the constriction amplitude at 9.5 seconds after light termination was related to the maximal constriction amplitude., Results: Rho-/- mice showed decreased constriction amplitude but more prolonged pupilloconstriction to all blue and red light stimuli compared to wild type mice. Cnga3-/- mice had constriction amplitudes similar to WT however following maximal constriction, the early and rapid dilation to low intensity blue light was decreased. To high intensity blue light, the Cnga3-/- mice demonstrated marked prolongation of the pupillary constriction. Cnga3-/-; Rho-/- mice had no pupil response to red light of low and medium intensity., Conclusions: From specific gene defective mouse models which selectively voided the rod or cone function, we determined that mouse rod photoreceptors are highly contributing to the pupil response to blue light stimuli but also to low and medium red stimuli. We also observed that cone cells mainly drive the partial rapid dilation of the initial response to low blue light stimuli. Thus photoreceptor dysfunction can be derived from chromatic pupillometry in mouse models.

Purpose: Diagnosis of peripheral neuropathy (PN), which affects approximately 50% of the diabetic population, is subjective, with many patients seeking a diagnosis only after presenting with symptoms. Recently, in vivo confocal microscopy of subepithelial corneal nerve density has been promoted as a surrogate marker for early detection of PN, but imaging of corneal nerves requires sophisticated instrumentation, expertise in confocal imaging, cooperative patients, and automated analysis tools to derive corneal nerve density. As an alternative, we developed a simple screening method that is based on the sensitivity of corneal nerves to cause reflex eyelid squinting in response to hyperosmolar eye drops., Methods: Eyes of control and type 2 diabetic rats were given an eye drop of a 290- to 900-mOsm solution, and the ocular response was video recorded. Other neuropathic end points including nerve conduction velocity and subepithelial cornea nerve density were determined., Results: Motor and sensory nerve conduction velocity and total nerve fiber length of corneal nerves in the subepithelial layer were significantly decreased in diabetic rats. Applying the hyperosmotic solutions to the ocular surface caused an osmolarity-dependent increase in squinting of the treated eye in control rats. Squinting was almost totally blocked by preapplication of proparacaine or N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine-1(2H)-carbox-amide, a transient receptor potential melastatin-8 channel blocker. Squinting in response to the 900-mOsm solution was significantly reduced in diabetic rats., Conclusions: Preclinical studies show that evaluation of corneal sensitivity may be an alternative method for the early detection of PN and has potential for translation to clinical studies.

Introduction: Approximately, 275,000 American service members deployed to Iraq or Afghanistan have sustained a mild traumatic brain injury (mTBI), with 75% of these incidents involving an explosive blast. Visual processing problems and cognitive dysfunction are common complaints following blast-related mTBI., Methods: In 127 veterans, we examined resting fMRI functional connectivity (FC) of four key nodes within the visual system: lateral geniculate nucleus (LGN), primary visual cortex (V1), lateral occipital gyrus (LO), and fusiform gyrus (FG). Regression analyses were performed (i) to obtain correlations between time-series from each seed and all voxels in the brain, and (ii) to identify brain regions in which FC variability was related to blast mTBI severity. Blast-related mTBI severity was quantified as the sum of the severity scores assigned to each of the three most significant blast-related injuries self-reported by subjects. Correlations between FC and performance on executive functioning tasks were performed across participants with available behavioral data (n = 94)., Results: Greater blast mTBI severity scores were associated with lower FC between: (A) LGN seed and (i) medial frontal gyrus, (ii) lingual gyrus, and (iii) right ventral anterior nucleus of thalamus; (B) V1 seed and precuneus; (C) LO seed and middle and superior frontal gyri; (D) FG seed and (i) superior and medial frontal gyrus, and (ii) left middle frontal gyrus. Finally, lower FC between visual network regions and frontal cortical regions predicted worse performance on the WAIS digit-symbol coding task., Conclusion: These are the first published results that directly illustrate the relationship between blast-related mTBI severity, visual pathway neural networks, and executive dysfunction - results that highlight the detrimental relationship between blast-related brain injury and the integration of visual sensory input and executive processes.

Aims . In this study a streptozotocin induced type 1 diabetes mouse model was used to assess the effectiveness of salsalate, menhaden oil, the combination of salsalate and menhaden oil, or resolvin D1 on neuropathic endpoints. Materials and Methods . Changes in body weight, blood glucose, serum markers for triglycerides, free fatty acids, cholesterol, and resolvin D1, motor and sensory nerve conduction velocities and thermal sensitivity were assessed, as well as performing in vivo confocal microscopy of subepithelial corneal nerves and immunohistochemistry of nerves in the cornea and foot pad. Results . Diabetic animals failed to gain weight and had elevated blood glucose levels. Diabetic mice had slowed nerve conduction velocity, reduced innervation of the foot pad and cornea subepithelial and epithelial layers, and reduced thermal sensitivity. Monotherapy treatment with salsalate, menhaden oil, and resolvin D1 reduced the pathological signs of diabetic neuropathy. The combination of salsalate and menhaden oil also reduced signs of pathology and generated elevated plasma levels of resolvin D1 compared to other groups. Conclusions . Additional studies are needed to determine whether the combination of salsalate and menhaden oil may be more efficacious than monotherapy alone for the treatment of diabetic peripheral neuropathy.

The purpose of this study was to determine the effect of supplementing the diet of a mouse model of type 2 diabetes with menhaden (fish) oil or daily treatment with resolvin D1 on diabetic neuropathy. The end points evaluated included motor and sensory nerve conduction velocity, thermal sensitivity, innervation of sensory nerves in the cornea and skin, and the retinal ganglion cell complex thickness. Menhaden oil is a natural source for n-3 polyunsaturated fatty acids, which have been shown to have beneficial effects in other diseases. Resolvin D1 is a metabolite of docosahexaenoic acid and is known to have anti-inflammatory and neuroprotective properties. To model type 2 diabetes, mice were fed a high-fat diet for 8 wk followed by a low dosage of streptozotocin. After 8 wk of hyperglycemia, mice in experimental groups were treated for 6 wk with menhaden oil in the diet or daily injections of 1 ng/g body wt resolvin D1. Our findings show that menhaden oil or resolvin D1 did not improve elevated blood glucose, HbA1C, or glucose utilization. Untreated diabetic mice were thermal hypoalgesic, had reduced motor and sensory nerve conduction velocities, had decreased innervation of the cornea and skin, and had thinner retinal ganglion cell complex. These end points were significantly improved with menhaden oil or resolvin D1 treatment. Exogenously, resolvin D1 stimulated neurite outgrowth from primary cultures of dorsal root ganglion neurons from normal mice. These studies suggest that n-3 polyunsaturated fatty acids derived from fish oil could be an effective treatment for diabetic neuropathy.

A 48-year-old man was examined 24 months after medial and surgical treatment of an isolated well-circumscribed right occipital lobe abscess. An asymptomatic residual left homonymous inferior scotoma was present. Fundus examination revealed temporal pallor of both optic discs, and optical coherence tomography (OCT) revealed mild temporal loss of retinal nerve fiber layer in both eyes. No relative afferent pupillary defect was present. Assessment of the retinal ganglion cell layer demonstrated homonymous thinning in a pattern corresponding to the homonymous visual field loss. There were no abnormalities of the lateral geniculate nuclei or optic tracts on review of the initial brain computed tomography and follow-up magnetic resonance imaging. We believe our patient showed evidence of transsynaptic retrograde degeneration after an isolated right occipital lobe lesion, and the homonymous neuronal loss was detected on OCT by assessing the retinal ganglion cell layer.

Purpose: To determine the etiology and prognosis of visual acuity loss in idiopathic intracranial hypertension (IIH) at presentation and to provide objective measures to predict visual outcome., Methods: A retrospective review of 660 patients with IIH (2009-2013) identified 31 patients (4.7%) with 48 eyes having best-corrected visual acuity (BCVA) of 20/25 or worse on initial presentation. Fundus photography, optical coherence tomography (OCT) of the optic disc and macula, and perimetry were used to determine the causes and prognosis of vision loss. Segmentation of the macula OCT was performed using the Iowa Reference Algorithm to determine the retinal ganglion cell-inner plexiform layer complex (GCL-IPL) thickness., Results: Outer retinal changes alone caused decreased BCVA at initial presentation in 22 eyes (46%): subretinal fluid in 16, chorioretinal folds in 5, and peripapillary choroidal neovascularization in 1. The vision loss was reversible except for some eyes with chorioretinal folds. Optic neuropathy alone caused decreased BCVA in 10 eyes (21%) and coexisting outer retinal changes and optic neuropathy caused decreased BCVA in 16 eyes (33%). A GCL-IPL thickness less than or equal to 70 μm at initial presentation or progressive thinning of greater than or equal to 10 μm within 2 to 3 weeks compared with baseline correlated with poor visual outcome., Conclusions: Visual acuity loss in IIH can be caused by both outer retinal changes and optic neuropathy. Vision loss from outer retinal changes is mostly reversible. The outcome of patients with coexisting outer retinal changes and optic neuropathy or optic neuropathy alone depends on the degree of optic neuropathy, which can be predicted by the GCL-IPL thickness.

Purpose: We characterized mitochondrial respiration and glycolysis activity of human corneal endothelium, and compared metabolic activity between central and peripheral regions., Methods: Endothelial keratoplasty-suitable corneas were obtained from donors aged 50 to 75 years. The endothelium-Descemet membrane complex (EDM) was isolated, and 3-mm punches were obtained from central and peripheral regions. Endothelium-Descemet membrane punches were assayed for mitochondrial respiration (oxygen consumption) and glycolysis (extracellular acidification) using an extracellular flux analyzer. Enzymatic (citrate synthase, glucose hexokinase) and mitochondrial density (MitoTracker) assays also were performed., Results: Ten corneas were analyzed per assay. Metabolic activity for mitochondrial respiration and glycolysis showed expected changes to assay compounds (P < 0.01, all pairwise comparisons). Basal mitochondrial respiration and glycolysis activity did not differ between regions (P > 0.99). Similarly, central versus peripheral activity after assay compound treatment showed no significant differences (P > 0.99, all time points). The intracorneal coefficient of variation for basal readings between two and four peripheral punches was 18.5% of the mean. Although peripheral samples displayed greater enzymatic activity than central samples (P < 0.05), similar to extracellular flux results, mitochondrial density did not differ between regions (P = 0.78)., Conclusions: Extracellular flux analysis of oxygen and pH is a valid technique for characterizing metabolic activity of human corneal endothelium. This technique demonstrates high reproducibility, allows quantification of metabolic parameters using small quantities of live cells, and permits estimation of overall metabolic output. Neither oxygen consumption nor extracellular acidification differed between central and peripheral regions of transplant suitable corneas in this series. Our results show that endothelial cell health can be quantified biochemically in transplant suitable corneas.

We determined the impact diet-induced obesity (DIO) and types 1 and 2 diabetes have on peripheral neuropathy with emphasis on corneal nerve structural changes in C57Bl/6J mice. Endpoints examined included nerve conduction velocity, response to thermal and mechanical stimuli and innervation of the skin and cornea. DIO mice and to a greater extent type 2 diabetic mice were insulin resistant. DIO and both types 1 and 2 diabetic mice developed motor and sensory nerve conduction deficits. In the cornea of DIO and type 2 diabetic mice there was a decrease in sub-epithelial corneal nerves, innervation of the corneal epithelium, and corneal sensitivity. Type 1 diabetic mice did not present with any significant changes in corneal nerve structure until after 20 weeks of hyperglycemia. DIO and type 2 diabetic mice developed corneal structural damage more rapidly than type 1 diabetic mice although hemoglobin A1 C values were significantly higher in type 1 diabetic mice. This suggests that DIO with or without hyperglycemia contributes to development and progression of peripheral neuropathy and nerve structural damage in the cornea., (© 2015 Peripheral Nerve Society.)

Many neuro-ophthalmic diseases have a clear sex predilection, which is important to recognize in making the diagnosis based on risk stratification and understanding the pathogenesis of the disease. This review discusses the more common neuro-ophthalmic diseases with a female predilection, including idiopathic intracranial hypertension, cerebral venous sinus thrombosis, meningioma, multiple sclerosis, migraine, breast-cancer associated neuro-ophthalmic manifestations, sarcoidosis, bisphosphonate-associated orbital inflammation, and pregnancy-related neuro-ophthalmic disorders. In addition, the male predominance in the clinical manifestation of Leber's Hereditary Optic Neuropathy is discussed. Lastly, the etiology of the sex discrepancies for each disease is explored.

Purpose: Traumatic brain injury (TBI) frequently leads to chronic visual dysfunction. The purpose of this study was to investigate the effect of TBI on retinal ganglion cells (RGCs), and to test whether treatment with the novel neuroprotective compound P7C3-S243 could prevent in vivo functional deficits in the visual system., Methods: Blast-mediated TBI was modeled using an enclosed over-pressure blast chamber. The RGC physiology was evaluated using a multielectrode array and pattern electroretinogram (PERG). Histological analysis of RGC dendritic field and cell number were evaluated at the end of the study. Visual outcome measures also were evaluated based on treatment of mice with P7C3-S243 or vehicle control., Results: We show that deficits in neutral position PERG after blast-mediated TBI occur in a temporally bimodal fashion, with temporary recovery 4 weeks after injury followed by chronically persistent dysfunction 12 weeks later. This later time point is associated with development of dendritic abnormalities and irreversible death of RGCs. We also demonstrate that ongoing pathologic processes during the temporary recovery latent period (including abnormalities of RGC physiology) lead to future dysfunction of the visual system. We report that modification of PERG to provocative postural tilt testing elicits changes in PERG measurements that correlate with a key in vitro measures of damage: the spontaneous and light-evoked activity of RGCs. Treatment with P7C3-S243 immediately after injury and throughout the temporary recovery latent period protects mice from developing chronic visual system dysfunction., Conclusions: Provocative PERG testing serves as a noninvasive test in the living organism to identify early damage to the visual system, which may reflect corresponding damage in the brain that is not otherwise detectable by noninvasive means. This provides the basis for developing an earlier diagnostic test to identify patients at risk for developing chronic CNS and visual system damage after TBI at an earlier stage when treatments may be more effective in preventing these sequelae. In addition, treatment with the neuroprotective agent P7C3-S243 after TBI protects from visual system dysfunction after TBI., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

A 41-year-old woman with skew deviation had cyclotorsion of both eyes. This resulted in a falsely low probability plot of retinal nerve fiber layer thickness in adjacent clock hours on optical coherence tomography (OCT) due to displacement of the retinal nerve fiber layer peaks. Ocular cyclotorsion may cause misinterpretation of OCT probability plots. OCT retinal nerve fiber layer plots also may be used to objectively quantify the degree of ocular cyclotorsion.

Purpose: Mutations in the RGS9 gene cause the visual disorder bradyopsia, which includes difficulty adapting to changes in light and photophobia. The purpose of this study was to determine whether lack of Rgs9 also caused photophobia-like behavior in Rgs9 knockout (Rgs9-/-) mice and to identify useful diagnostic measures of Rgs9 dysfunction., Methods: We measured two behavioral responses to light and the pupillary light reflex to determine the form and basis of photophobia in Rgs9-/- mice., Results: Rgs9-/- mice spent less time than wild-type mice in both dim and bright light. The mice also showed increased sensitivity to light in negative masking behavior, with a half maximal response at 0.08 lux (0.01 μW·cm(-2)) in Rgs9-/- mice compared to 5.0 lux (0.85 μW·cm(-2)) in wild-type mice. These behaviors were not due to increased anxiety or increased pupil size causing more light to enter the eye. Rather, constriction of the pupil showed that Rgs9-/- mice had an abnormally sustained response to light across multiple irradiance measurement pathways., Conclusions: Rgs9-/- mice recapitulate a photophobia phenotype of bradyopsia, and the pupil light reflex identifies a simple means to screen for irradiance measurement abnormalities in bradyopsia and potentially other genetic disorders involving photophobia., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

We sought to determine the impact that duration of hyperglycemia and control has on corneal nerve fiber density in relation to standard diabetic neuropathy endpoints. Control and streptozotocin-diabetic C57Bl/6J mice were analyzed after 4, 8, 12, and 20 weeks. For the 20-week time point, five groups of mice were compared: control, untreated diabetic, and diabetic treated with insulin designated as having either poor glycemic control, good glycemic control, or poor glycemic control switched to good glycemic control. Hyperglycemia was regulated by use of insulin-releasing pellets. Loss of corneal nerves in the sub-epithelial nerve plexus or corneal epithelium progressed slowly in diabetic mice requiring 20 weeks to reach statistical significance. In comparison, slowing of motor and sensory nerve conduction velocity developed rapidly with significant difference compared with control mice observed after 4 and 8 weeks of hyperglycemia, respectively. In diabetic mice with good glycemic control, average blood glucose levels over the 20-week experimental period were lowered from 589 ± 2 to 251 ± 9 mg/dl. All diabetic neuropathy endpoints examined were improved in diabetic mice with good glycemic control compared with untreated diabetic mice. However, good control of blood glucose was not totally sufficient in preventing diabetic neuropathy., (© 2014 Peripheral Nerve Society.)

Purpose: Peripheral neuropathy has been shown to exist in prediabetic and diabetic patients and animal models. However, the development of peripheral neuropathy in prediabetes and posthyperglycemia is likely different. The purpose of this study was to examine the progression of peripheral neuropathy in diet-induced obese rats and high-fat-fed rats treated with a low dose of streptozotocin, a model for type 2 diabetes, using standard endpoints as well as corneal sensitivity and innervation., Methods: Diet-induced obese rats and high-fat/low-dose streptozotocin diabetic rats were used to examine standard peripheral neuropathy endpoints and innervation of the cornea and corneal epithelium using corneal and standard confocal microscopy, respectively, and corneal sensitivity using a Cochet-Bonnet esthesiometer at three different time points., Results: Obese rats and to a greater extent diabetic rats were insulin resistant. Obese and diabetic rats had developed sensory nerve deficits, but only diabetic rats had motor nerve dysfunction as determined by measuring nerve conduction velocity, thermal nociception, and intraepidermal nerve fiber density. In the cornea there was a decrease in corneal nerve fiber length, innervation of the corneal epithelium, and corneal sensitivity in both diet-induced obese and diabetic rats., Conclusions: These studies demonstrate that changes in corneal nerve innervation and sensitivity occur in both obese and type 2 diabetic rat models that are consistent with development of peripheral neuropathy. Examination of corneal nerve changes may be valuable endpoints for exploring potential treatments for peripheral neuropathy in both prediabetes with insulin resistance and diabetes.

Purpose: We determined the effect of entrance pupil size on retinal illumination. The influence of unilateral miosis on the magnitude of the pupil light reflex was studied to ascertain how a clinically significant anisocoria influences the relative afferent pupil defect (RAPD)., Methods: Miosis was induced by topical 1% pilocarpine in the right eye of 14 healthy subjects with normal eyes. The interocular difference in retinal illumination was assessed by computerized pupillometry from the stimulus response curve of the right and left eyes. The main outcome measure was the RAPD, determined by computerized pupillography, at baseline and after pilocarpine-induced anisocoria., Results: Induced anisocoria produced a significant change in RAPD from baseline (mean = 1.60 dB in the miotic eye, P = 0.007). However, anisocoria correlated with RAPD only in subjects with darkly pigmented irides (Pearson correlation coefficient 0.793, P = 0.05)., Conclusions: In darkly pigmented eyes, entrance pupil size significantly influenced the retinal illumination. However, retinal illumination of lightly pigmented eyes is relatively independent of entrance pupil size, presumably due to extrapupillary transmission of light through the iris and sclera. This has important implications in understanding the potential influence of anisocoria on the RAPD and also greater susceptibility of lightly pigmented eyes to light toxicity.

Background: Automated detection of subtle changes in peripapillary retinal nerve fibre layer thickness (RNFLT) over time using optical coherence tomography (OCT) is limited by inherent image quality before layer segmentation, stabilization of the scan on the peripapillary retina and its precise placement on repeated scans. The present study evaluates image quality and reproducibility of spectral domain (SD)-OCT comparing different rates of automatic real-time tracking (ART)., Methods: Peripapillary RNFLT was measured in 40 healthy eyes on six different days using SD-OCT with an eye-tracking system. Image brightness of OCT with unaveraged single frame B-scans was compared to images using ART of 16 B-scans and 100 averaged frames. Short-term and day-to-day reproducibility was evaluated by calculation of intraindividual coefficients of variation (CV) and intraclass correlation coefficients (ICC) for single measurements as well as for seven repeated measurements per study day., Results: Image brightness, short-term reproducibility, and day-to-day reproducibility were significantly improved using ART of 100 frames compared to one and 16 frames. Short-term CV was reduced from 0.94 ± 0.31 % and 0.91 ± 0.54 % in scans of one and 16 frames to 0.56 ± 0.42 % in scans of 100 averaged frames (P ≤ 0.003 each). Day-to-day CV was reduced from 0.98 ± 0.86 % and 0.78 ± 0.56 % to 0.53 ± 0.43 % (P ≤ 0.022 each). The range of ICC was 0.94 to 0.99. Sample size calculations for detecting changes of RNFLT over time in the range of 2 to 5 μm were performed based on intraindividual variability., Conclusion: Image quality and reproducibility of mean peripapillary RNFLT measurements using SD-OCT is improved by averaging OCT images with eye-tracking compared to unaveraged single frame images. Further improvement is achieved by increasing the amount of frames per measurement, and by averaging values of repeated measurements per session. These strategies may allow a more accurate evaluation of RNFLT reduction in clinical trials observing optic nerve degeneration.

Purpose: To evaluate retina and optic nerve damage following experimental blast injury., Methods: Healthy adult mice were exposed to an overpressure blast wave using a custom-built blast chamber. The effects of blast exposure on retina and optic nerve function and structure were evaluated using the pattern electroretinogram (pERG), spectral domain optical coherence tomography (OCT), and the chromatic pupil light reflex., Results: Assessment of the pupil response to light demonstrated decreased maximum pupil constriction diameter in blast-injured mice using red light or blue light stimuli 24 hours after injury compared with baseline in the eye exposed to direct blast injury. A decrease in the pupil light reflex was not observed chronically following blast exposure. We observed a biphasic pERG decrease with the acute injury recovering by 24 hours postblast and the chronic injury appearing at 4 months postblast injury. Furthermore, at 3 months following injury, a significant decrease in the retinal nerve fiber layer was observed using OCT compared with controls. Histologic analysis of the retina and optic nerve revealed punctate regions of reduced cellularity in the ganglion cell layer and damage to optic nerves. Additionally, a significant upregulation of proteins associated with oxidative stress was observed acutely following blast exposure compared with control mice., Conclusions: Our study demonstrates that decrements in retinal ganglion cell responses can be detected after blast injury using noninvasive functional and structural tests. These objective responses may serve as surrogate tests for higher CNS functions following traumatic brain injury that are difficult to quantify.

Purpose: To study and correct for the limiting effect of iris mechanics on the amplitude of light-evoked pupil contractions in order to derive a more clinically accurate assessment of afferent input to the visual system., Methods: Transient pupil responses were recorded to a series of 1-second red Ganzfeld light stimuli with a stepwise increase in stimulus intensity using a binocular infrared computerized pupillometer. One eye of eight healthy subjects was treated with 0.2% brimonidine tartrate ophthalmic solution to induce pupil size reduction. The amount of pupil contraction as a function of stimulus intensity was compared between the brimonidine-treated, miotic eye and the untreated eye., Results: BRIMONIDINE TREATMENT PRODUCED SIGNIFICANT REDUCTION IN PUPIL SIZE IN HEALTHY SUBJECTS (MEAN REDUCTION IN PUPIL SIZE: 1.78 ± 0.35 mm, P < 0.05). For increasing light intensity, the treated pupil started to show reduced pupil contractions compared with the contralateral untreated pupil when the peak of pupil contraction reached an average pupil size of 3.25 ± 0.61 mm (range, 2.38-4.44 mm). When measured by percent pupil contraction (contraction amplitude/baseline pupil diameter), the pupil response as a function of stimulus intensity in the treated, miotic eye did not differ from that in the untreated eye., Conclusions: Iris mechanics limits the amount of pupil contraction and can act to reduce the assessed neuronal integration of the pupil light reflex. Pupil response assessed by using percent contraction amplitude is least affected by mechanical effects and provides a more accurate approximation of afferent input.

Objective: To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes., Animal Studied: Adult C57BL/6 male mice (n = 37)., Procedures: Retinal function was evaluated using pattern electroretinography (pERG) and the chromatic pupil light reflex (cPLR). Structural properties of the retina and nerve fiber layer (NFL) were evaluated using spectral-domain optical coherence tomography (SD-OCT)., Results: The average pERG amplitudes were found to be 11.2 ± 0.7 μV (P50-N95, mean ± SEM), with an implicit time for P50-N95 interval of 90.4 ± 5.4 ms. Total retinal thickness was 229.5 ± 1.7 μm (mean ± SEM) in the area centralis region. The thickness of the retinal nerve fiber layer (mean ± SEM) using a circular peripapillary retinal scan centered on the optic nerve was 46.7 ± 0.9 μm (temporal), 46.1 ± 0.9 μm (superior), 45.8 ± 0.9 μm (nasal), and 48.4 ± 1 μm (inferior). The baseline pupil diameter was 2.1 ± 0.05 mm in darkness, and 1.1 ± 0.05 and 0.56 ± 0.03 mm after stimulation with red (630 nm, luminance 200 kcd/m(2)) or blue (480 nm, luminance 200 kcd/m(2)) light illumination, respectively., Conclusions: Pattern electroretinography, cPLR and SD-OCT analysis are reproducible techniques, which can provide important information about retinal and optic nerve function and structure in mice., (© 2012 American College of Veterinary Ophthalmologists.)

Purpose: To derive a computerized measurement of optic disc volume from digital stereoscopic fundus photographs for the purpose of diagnosing and managing papilledema., Methods: Twenty-nine pairs of stereoscopic fundus photographs and optic nerve head (ONH) centered spectral domain optical coherence tomography (SD-OCT) scans were obtained at the same visit in 15 patients with papilledema. Some patients were imaged at multiple visits in order to assess their changes. Three-dimensional shape of the ONH was estimated from stereo fundus photographs using an automated multi-scale stereo correspondence algorithm. We assessed the correlation of the stereo volume measurements with the SD-OCT volume measurements quantitatively, in terms of volume of retinal surface elevation above a reference plane and also to expert grading of papilledema from digital fundus photographs using the Frisén grading scale., Results: The volumetric measurements of retinal surface elevation estimated from stereo fundus photographs and OCT scans were positively correlated (correlation coefficient r(2) = 0.60; P < 0.001) and were positively correlated with Frisén grade (Spearman correlation coefficient r = 0.59; P < 0.001)., Conclusions: Retinal surface elevation among papilledema patients obtained from stereo fundus photographs compares favorably with that from OCT scans and with expert grading of papilledema severity. Stereoscopic color imaging of the ONH combined with a method of automated shape reconstruction is a low-cost alternative to SD-OCT scans that has potential for a more cost-effective diagnosis and management of papilledema in a telemedical setting. An automated three-dimensional image analysis method was validated that quantifies the retinal surface topography with an imaging modality that has lacked prior objective assessment.

Purpose: To develop an automated method for the quantification of volumetric optic disc swelling in papilledema subjects using spectral-domain optical coherence tomography (SD-OCT) and to determine the extent that such volumetric measurements correlate with Frisén scale grades (from fundus photographs) and two-dimensional (2-D) peripapillary retinal nerve fiber layer (RNFL) and total retinal (TR) thickness measurements from SD-OCT., Methods: A custom image-analysis algorithm was developed to obtain peripapillary circular RNFL thickness, TR thickness, and TR volume measurements from SD-OCT volumes of subjects with papilledema. In addition, peripapillary RNFL thickness measures from the commercially available Zeiss SD-OCT machine were obtained. Expert Frisén scale grades were independently obtained from corresponding fundus photographs., Results: In 71 SD-OCT scans, the mean (± standard deviation) resulting TR volumes for Frisén scale 0 to scale 4 were 11.36 ± 0.56, 12.53 ± 1.21, 14.42 ± 2.11, 17.48 ± 2.63, and 21.81 ± 3.16 mm(3), respectively. The Spearman's rank correlation coefficient was 0.737. Using 55 eyes with valid Zeiss RNFL measurements, Pearson's correlation coefficient (r) between the TR volume and the custom algorithm's TR thickness, the custom algorithm's RNFL thickness, and Zeiss' RNFL thickness was 0.980, 0.929, and 0.946, respectively. Between Zeiss' RNFL and the custom algorithm's RNFL, and the study's TR thickness, r was 0.901 and 0.961, respectively., Conclusions: Volumetric measurements of the degree of disc swelling in subjects with papilledema can be obtained from SD-OCT volumes, with the mean volume appearing to be roughly linearly related to the Frisén scale grade. Using such an approach can provide a more continuous, objective, and robust means for assessing the degree of disc swelling compared with presently available approaches.

Purpose: Mutations in the myocilin gene (MYOC) are the most common known genetic cause of primary open-angle glaucoma (POAG). The purpose of this study was to determine whether topical ocular sodium 4-phenylbutyrate (PBA) treatment rescues glaucoma phenotypes in a mouse model of myocilin-associated glaucoma (Tg-MYOC(Y437H) mice)., Methods: Tg-MYOC(Y437H) mice were treated with PBA eye drops (n = 10) or sterile PBS (n = 8) twice daily for 5 months. Long-term safety and effectiveness of topical PBA (0.2%) on glaucoma phenotypes were examined by measuring intraocular pressure (IOP) and pattern ERG (PERG), performing slit lamp evaluation of the anterior chamber, analyzing histologic sections of the anterior segment, and comparing myocilin levels in the aqueous humor and trabecular meshwork of Tg-MYOC(Y437H) mice., Results: Tg-MYOC(Y437H) mice developed elevated IOP at 3 months of age when compared with wild-type (WT) littermates (n = 24; P < 0.0001). Topical PBA did not alter IOP in WT mice. However, it significantly reduced elevated IOP in Tg-MYOC(Y437H) mice to the level of WT mice. Topical PBA-treated Tg-MYOC(Y437H) mice also preserved PERG amplitudes compared with vehicle-treated Tg-MYOC(Y437H) mice. No structural abnormalities were observed in the anterior chamber of PBA-treated WT and Tg-MYOC(Y437H) mice. Analysis of the myocilin in the aqueous humor and TM revealed that PBA significantly improved the secretion of myocilin and reduced myocilin accumulation as well as endoplasmic reticulum (ER) stress in the TM of Tg-MYOC(Y437H) mice. Furthermore, topical PBA reduced IOP elevated by induction of ER stress via tunicamycin injections in WT mice., Conclusions: Topical ocular PBA reduces glaucomatous phenotypes in Tg-MYOC(Y437H) mice, most likely by reducing myocilin accumulation and ER stress in the TM. Topical ocular PBA could become a novel treatment for POAG patients with myocilin mutations.

Objective: To compare loss in sensitivity measured using standard automated perimetry (SAP) with local retinal ganglion cell layer (RGC) thickness measured using frequency-domain optical coherence tomography in the macula of patients with glaucoma., Methods: To compare corresponding locations of RGC thickness with total deviation (TD) of 10-2 SAP for 14 patients with glaucoma and 19 controls, an experienced operator hand-corrected automatic segmentation of the combined RGC and inner plexiform layer (RGC+IPL) of 128 horizontal B-scans. To account for displacement of the RGC bodies around the fovea, the location of the SAP test points was adjusted to correspond to the location of the RGC bodies rather than to the photoreceptors, based on published histological findings. For analysis, RGC+IPL thickness vs SAP (TD) data were grouped into 5 eccentricities, from 3.4° to 9.7° radius on the retina with respect to the fovea., Results: The RGC+IPL thickness correlated well with SAP loss within approximately 7.2° of the fovea (Spearman ρ = 0.71-0.74). Agreement was worse (0.53-0.65) beyond 7.2°, where the normal RGC layer is relatively thin. A linear model relating RGC+IPL thickness to linear SAP loss provided a reasonable fit for eccentricities within 7.2°., Conclusion: In the central 7.2°, local RGC+IPL thickness correlated well with local sensitivity loss in glaucoma when the data were adjusted for RGC displacement.

A healthy 11-year-old girl presented with right upper eyelid retraction since birth. An evaluation including thyroid function studies and neuroimaging was negative, and the patient was scheduled for a right levator recession to address the eyelid malposition. Intraoperatively, after the induction of inhalational general anesthesia, the patient displayed cyclic right upper eyelid retraction. Occurring in intervals of exactly 48 seconds, these cycles involved a rapid elevation of the right eyelid from a position of half-closure to a retracted position just above the superior limbus. There was no change in pupil size or eye position during these cyclic spasms, and the contralateral eyelid was unaffected. The patient underwent an uncomplicated levator recession, which improved the upper eyelid retraction. Postoperative testing, including external motility video and infrared pupillometry, demonstrated no cyclic variation in eyelid position, eye position, or pupil size in the waking state. This is a unique case of unilateral eyelid retraction with periodic spasms under conditions of anesthesia without a preexisting oculomotor paresis; it represents an unusual variation on congenital eyelid retraction and classically described cyclic oculomotor palsy.

Background: Recent improvements in optical coherence tomographic (OCT) resolution and automated segmentation software have provided a means of relating visual pathway damage to structural changes in the retinal nerve fiber layer (RNFL) and corresponding soma of the ganglion cells in the inner layers of the macula and also in the outer photoreceptor layer in the macula., Evidence Acquisition: Studies correlating retinal structure with function are reviewed in the context of OCT in optic nerve and retinal disorders., Results: Recently published work provides evidence showing a strong relationship not only between the RNFL and visual threshold in optic nerve disorders but also between visual sensitivity and the inner layers of the retina in the macula, where the cell bodies of ganglion cells reside. Acquired and genetic disorders affecting the outer retina show correlation between visual sensitivity and the thickness of the outer photoreceptors. These relationships help localize unknown causes of visual field loss through segmentation of the retinal layers using spectral domain OCT., Conclusions: Advances in relating the structure of the ganglion cell layer in the macula to the corresponding axons in the RNFL and to visual function further our ability to differentiate and localize ambiguous causes of vision loss and visual field defects in neuro-ophthalmology. Ganglion cell layer analysis in volume OCT data may provide yet another piece of the puzzle to understanding structure-function relationships and its application to diagnosis and monitoring of optic nerve diseases, while similar structure-function relationships are also being elucidated in the outer retina for photoreceptor diseases.

PURPOSE. To examine the biomechanical deformation of load bearing structures of the optic nerve head (ONH) resulting from raised intracranial pressure, using high definition optical coherence tomography (HD-OCT). The authors postulate that elevated intracranial pressure induces forces in the retrolaminar subarachnoid space that can deform ONH structures, particularly the peripapillary Bruch's membrane (BM) and RPE layers. METHODS. The authors compared HD-OCT optic nerve and peripapillary retinal nerve fiber layer (RNFL) findings in eyes with papilledema caused by raised intracranial pressure to findings in eyes with optic disc swelling caused by optic neuritis and nonarteritic anterior ischemic optic neuropathy (NAION), conditions without intracranial hypertension. The authors measured average thickness of the RNFL and the angle of the RPE/BM at the temporal and nasal borders of the neural canal opening. The angle was measured as positive with inward (toward the vitreous) angulation and as negative with outward angulation. RESULTS. Of 30 eyes with papilledema, 20 eyes (67%) had positive RPE/BM rim angles. One of eight optic neuritis (12%) eyes and 1 of 12 NAION (8%) eyes had positive angulation. In five eyes with papilledema, RNFL thickening increased, three of which developed positive RPE/BM angles. On follow-up, 22 papilledema eyes had a reduction of RNFL swelling, and 17 of these eyes had less positive RPE/BM angulation. CONCLUSIONS. In papilledema, the RPE/BM is commonly deflected inward, in contrast to eyes with NAION or optic neuritis. The RPE/BM angulation is presumed to be caused by elevated pressure in the subarachnoid space, does not correlate with the amount of RNFL swelling, and resolves as papilledema subsides.

PURPOSE. To better understand the relative contributions of rod, cone, and melanopsin to the human pupillary light reflex (PLR) and to determine the optimal conditions for assessing the health of the rod, cone, and melanopsin pathways with a relatively brief clinical protocol. METHODS. PLR was measured with an eye tracker, and stimuli were controlled with a Ganzfeld system. In experiment 1, 2.5 log cd/m(2) red (640 ± 10 nm) and blue (467 ± 17 nm) stimuli of various durations were presented after dark adaptation. In experiments 2 and 3, 1-second red and blue stimuli were presented at different intensity levels in the dark (experiment 2) or on a 0.78 log cd/m(2) blue background (experiment 3). Based on the results of experiments 1 to 3, a clinical protocol was designed and tested on healthy control subjects and patients with retinitis pigmentosa and Leber's congenital amaurosis. RESULTS. The duration for producing the optimal melanopsin-driven sustained pupil response after termination of an intense blue stimulus was 1 second. PLR rod- and melanopsin-driven components are best studied with low- and high-intensity flashes, respectively, presented in the dark (experiment 2). A blue background suppressed rod and melanopsin responses, making it easy to assess the cone contribution with a red flash (experiment 3). With the clinical protocol, robust melanopsin responses could be seen in patients with few or no contributions from the rods and cones. CONCLUSIONS. It is possible to assess the rod, cone, and melanopsin contributions to the PLR with blue flashes at two or three intensity levels in the dark and one red flash on a blue background.

Purpose: To evaluate the ability of mesenchymal stem cells (MSCs) engineered to produce and secrete brain-derived neurotrophic factor (BDNF) to protect retinal function and structure after intravitreal transplantation in a rat model of chronic ocular hypertension (COH)., Methods: COH was induced by laser cauterization of trabecular meshwork and episcleral veins in rat eyes. COH eyes received an intravitreal transplant of MSCs engineered to express BDNF and green fluorescent protein (BDNF-MSCs) or just GFP (GFP-MSCs). Computerized pupillometry and electroretinography (ERG) were performed to assess optic nerve and retinal function. Quantification of optic nerve damage was performed by counting retinal ganglion cells (RGCs) and evaluating optic nerve cross-sections., Results: After transplantation into COH eyes, BDNF-MSCs preserved significantly more retina and optic nerve function than GFP-MSC-treated eyes when pupil light reflex (PLR) and ERG function were evaluated. PLR analysis showed significantly better function (P = 0.03) in BDNF-MSC-treated eyes (operated/control ratio = 63.00% ± 11.39%) than GFP-MSC-treated eyes (operated/control ratio = 31.81% ± 9.63%) at 42 days after surgery. The BDNF-MSC-transplanted eyes also displayed a greater level of RGC preservation than eyes that received the GFP-MSCs only (RGC cell counts: BDNF-MSC-treated COH eyes, 112.2 ± 19.39 cells/section; GFP-MSC-treated COH eyes, 52.21 ± 11.54 cells/section; P = 0.01)., Conclusions: The authors have demonstrated that lentiviral-transduced BDNF-producing MSCs can survive in eyes with chronic hypertension and can provide retina and optic nerve functional and structural protection. Transplantation of BDNF-producing stem cells may be a viable treatment strategy for glaucoma.

Purpose: Detection of light in the eye contributes both to spatial awareness (form vision) and to responses that acclimate an animal to gross changes in light (irradiance detection). This dual role means that eye disease that disrupts form vision can also adversely affect physiology and behavioral state. The purpose of this study was to investigate how inner retinal circuitry mediating rod-cone photoreceptor input contributes to functionally distinct irradiance responses and whether that might account for phenotypic diversity in retinal disease., Methods: The sensitivity of the pupillary light reflex and negative masking (activity suppression by light) was measured in wild-type mice with intact inner retinal circuitry, Nob4 mice that lack ON-bipolar cell function, and rd1 mice that lack rods and cones and, therefore, have no input to ON or OFF bipolar cells., Results: An expected increase in sensitivity to negative masking with loss of photoreceptor input in rd1 was duplicated in Nob4 mice. In contrast, sensitivity of the pupillary light reflex was more severely reduced in rd1 than in Nob4 mice., Conclusions: Absence of ON-bipolar cell-mediated rod-cone input can fully explain the phenotype of outer retina degeneration for negative masking but not for the pupillary light reflex. Therefore, inner retinal pathways mediating rod-cone input are different for negative masking and the pupillary light reflex.

Objective: To describe the clinical, molecular, and serologic findings of a case in which autoimmune retinopathy and early-onset heritable retinal degeneration were both considered in the differential diagnosis., Methods: A 3-year-old girl had clinical findings suggestive of a childhood-onset retinal degeneration. Samples of DNA and serum were collected. The coding regions of 11 genes associated with Leber congenital amaurosis were sequenced. The patient's serum reactivity to soluble and insoluble fractions of human retinal protein was compared with that of healthy control subjects (n = 32), patients with inflammatory eye disease (n = 80), and patients with molecularly confirmed retinal degenerations (n = 11). Two-dimensional gel electrophoresis and mass spectrometry were used to identify a protein that corresponded to a reactive band on Western blot., Results: No plausible disease-causing mutations were identified in any of the retinal disease genes tested. However, the patient's serum showed reactivity to a single retinal antigen of approximately 47 kDa. Two-dimensional gel electrophoresis and mass spectrometry revealed the major reactive species to be neuron-specific enolase (NSE). Autoantibodies targeting NSE were not observed in any healthy control subjects or patients with inflammatory eye disease. However, anti-NSE activity was found in 1 child with molecularly confirmed Leber congenital amaurosis., Conclusion: This patient's clinical and laboratory findings coupled with the recently discovered role of anti-NSE antibodies in canine autoimmune retinopathy suggest that autoantibodies targeting NSE are involved in the pathogenesis of her disease., Clinical Relevance: Infection or inflammation within the retina early in life may lead to an autoimmune phenocopy of early-onset inherited retinal degeneration.

Purpose: The pathophysiological events that occur in advanced glaucoma are not well characterized. The principal purpose of this study is to characterize the gene expression changes that occur in advanced glaucoma., Methods: Retinal RNA was obtained from canine eyes with advanced glaucoma as well as from healthy eyes. Global gene expression patterns were determined using oligonucleotide microarrays and confirmed by real-time PCR. The presence of tumor necrosis factor (TNF) and its receptors was evaluated by immunolabeling. Finally, we evaluated the presence of serum autoantibodies directed against retinal epitopes using western blot analyses., Results: We identified over 500 genes with statistically significant changes in expression level in the glaucomatous retina. Decreased expression levels were detected for large number of functional groups, including synapse and synaptic transmission, cell adhesion, and calcium metabolism. Many of the molecules with decreased expression levels have been previously shown to be components of retinal ganglion cells. Genes with elevated expression in glaucoma are largely associated with inflammation, such as antigen presentation, protein degradation, and innate immunity. In contrast, expression of many other pro-inflammatory genes, such as interferons or interleukins, was not detected at abnormal levels., Conclusions: This study characterizes the molecular events that occur in the canine retina with advanced glaucoma. Our data suggest that in the dog this stage of the disease is accompanied by pronounced retinal neuroinflammation.

Background: To characterize the molecular and functional status of the rat retina and optic nerve after acute elevation of intraocular pressure (IOP)., Methods: Retinal ischemia was induced in rats by increasing the IOP (110 mmHg/60 minutes). Microarray analysis, quantitative RT-PCR (qRT-PCR) and immunohistochemistry were used to characterize retinal tissue. PLGA microspheres containing neurotrophic factors (BDNF, GDNF, or CNTF) or empty microspheres were injected into the vitreous of operated animals 1 day after elevation of IOP. Pupil light reflex (PLR) parameters and electroretinograms (ERG) were monitored at multiple time points during the 60-day postoperative recovery period., Results: Molecular analysis showed a significant intrinsic up-regulation of CNTF at 10 and 25 days after induction of the acute ocular hypertension (p = 0.0067). Molecular tissue analysis of GDNF and its receptors (GDNFR1, GDNFR2), and BDNF and its receptor (trkB) showed no change in expression. Animals that received CNTF microspheres had no significant functional recovery compared to animals which received blank microspheres (p > 0.05). Animals that received GDNF or BDNF microspheres showed significant PLR recovery (p < 0.05 and p < 0.001 respectively) compared to non-treated animals., Conclusions: Continuous release of neurotrophic growth factors (NGFs) significantly protects optic nerve function in the experimental model of retinal ischemia observed by PLR analysis.

Objectives: To compare and contrast 2 methods of quantitating papilledema, namely, optical coherence tomography (OCT) and Modified Frisén Scale (MFS)., Methods: Digital optic disc photographs and OCT fast retinal nerve fiber layer (RNFL) thickness, fast RNFL map, total retinal thickness, and fast disc images were obtained in 36 patients with papilledema. Digital optic disc photographs were randomized and graded by 4 masked expert reviewers using the MFS. We performed Spearman rank correlations of OCT RNFL thickness, OCT total retinal thickness, and MFS grade from photographs., Results: OCT RNFL thickness and MFS grade from photographs correlated well (R = 0.85). OCT total retinal thickness and MFS grade from photographs had a similar correlation of 0.87. Comparing OCT RNFL thickness with OCT total retinal thickness, a slope of 1.64 suggests a greater degree of papilledema thickness change when using the latter., Conclusions: For lower-grade abnormalities, OCT compares favorably with clinical staging of optic nerve photographs. With higher grades, OCT RNFL thickness processing algorithms often fail, with OCT total retinal thickness performing more favorably.

Objective: To understand how progressive rod cone degeneration due to a mutation in CEP290 affects the pupillary light reflex (PLR) in domestic cats., Animals Studied: Domestic cats identified as either normal wildtype (WT; n = 6), or homozygous for the rdAc mutation in CEP290 and having early stage retinal degeneration (stage 2, S2; n = 4), or advanced retinal degeneration (S4; n = 6)., Methods: The effect of light on pupil size was measured over a series of 10-s pulses of white and chromatic light in cats lightly sedated with medetomidine., Results: In WT cats, the PLR was characterized by a pronounced initial constriction that rapidly re-dilated during the stimulus (pupil escape), to a stable or sustained constriction. There was then a marked constriction at stimulus offset. Each component of the PLR was retained in affected cats, but with progressively reduced irradiance sensitivity from early to advanced retinal disease., Conclusions: The PLR of cats had multiple phases, with a remarkably high-amplitude 'paradoxical' off-constriction even in the absence of retinal disease. In rdAc cats, reduced irradiance sensitivity was consistent with progressive loss of rod and cone function. Based on previously characterized retinal pathology, this suggests the visual streak of the retina has a proportionally large contribution to PLR input. These findings support the hypothesis that the efficacy of planned therapeutic trials can be determined by careful evaluation of the PLR in cats.

Purpose: To characterize functional and structural changes in a canine model of hereditary primary angle-closure glaucoma., Methods: Intraocular pressure (IOP) was evaluated with tonometry in a colony of glaucomatous dogs at 8, 15, 18, 20, and 30 months of age. Retinal function was evaluated using electroretinography (scotopic, photopic, and pattern). Examination of anterior segment structures was performed using gonioscopy and high-frequency ultrasonography (HFU)., Results: A gradual rise in IOP was observed with an increase in age: 8 months, 14 mm Hg (median value); 15 months, 15.5 mm Hg; 18 months, 17.5 mm Hg; 20 months, 24 mm Hg; 30 months, 36 mm Hg. Provocative testing with mydriatic agents (tropicamide and atropine 1%) caused significant increases in IOP (35% and 50%, respectively). HFU analysis showed complete collapse of iridocorneal angles by 20 months of age. Scotopic and photopic ERG analysis did not reveal significant deficits, but pattern ERG analysis showed significantly reduced amplitudes in glaucomatous dogs (glaucoma, 3.5 +/- 0.4 muV; control, 6.2 +/- 0.3 muV; P = 0.004; Student's t-test). Histologic analysis revealed collapse of the iridocorneal angle, posterior bowing of the lamina cribrosa, swelling and loss of large retinal ganglion cells, increased glial reactivity, and increased thickening of the lamina cribrosa., Conclusions: Canine hereditary angle-closure glaucoma is characterized by a progressive increase in intraocular pressure, loss of optic nerve function, and retinal ganglion cell loss.

Purpose: Retinal nerve fiber (RNFL) thickness and visual field loss data from patients with glaucoma were analyzed in the context of a model, to better understand individual variation in structure versus function., Methods: Optical coherence tomography (OCT) RNFL thickness and standard automated perimetry (SAP) visual field loss were measured in the arcuate regions of one eye of 140 patients with glaucoma and 82 normal control subjects. An estimate of within-individual (measurement) error was obtained by repeat measures made on different days within a short period in 34 patients and 22 control subjects. A linear model, previously shown to describe the general characteristics of the structure-function data, was extended to predict the variability in the data., Results: For normal control subjects, between-individual error (individual differences) accounted for 87% and 71% of the total variance in OCT and SAP measures, respectively. SAP within-individual error increased and then decreased with increased SAP loss, whereas OCT error remained constant. The linear model with variability (LMV) described much of the variability in the data. However, 12.5% of the patients' points fell outside the 95% boundary. An examination of these points revealed factors that can contribute to the overall variability in the data. These factors include epiretinal membranes, edema, individual variation in field-to-disc mapping, and the location of blood vessels and degree to which they are included by the RNFL algorithm., Conclusions: The model and the partitioning of within- versus between-individual variability helped elucidate the factors contributing to the considerable variability in the structure-versus-function data.

Objective: To derive and display the percentile score (1st-99th percentile) at each perimetric location of a standard automated perimetry test to determine whether this technique will uncover patterns of loss not visible in standard (StatPac) probability maps., Methods: We computed continuous scale probability plots of data collected from testing 305 visually healthy participants with standard automated perimetry (24-2 Swedish interactive thresholding algorithm). The age-corrected thresholds were sorted by sensitivity at each visual field location. Percentiles were derived in single increments from the 1st to the 99th. We displayed the percentiles as a color scale and then interpreted visual field plots from healthy control subjects and patients with visual system disorders., Results: Added information was achieved for identifying patterns of visual loss by using the 5th- to 20th-percentile range in conjunction with the lower range below the 5th percentile that is typically used. The extent of contiguous regional defects appeared larger using this method. Healthy control subjects often have threshold results within the 5th- to 20th-percentile range, but these test locations usually appeared randomly spaced rather than in contiguous patterns commonly seen in patients at the border of visual field defects., Conclusion: Continuous scale probability plots are a potentially useful adjunct for interpretation of perimetry results.