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Genetic disorders that present during development make treatment strategies particularly challenging because there is a need to disentangle primary pathophysiology from downstream dysfunction caused at key developmental stages. To provide a deeper insight into this question, we studied a mouse model of X-linked juvenile retinoschisis, an early-onset inherited condition caused by mutations in the Rs1 gene encoding retinoschisin (RS1) and characterized by cystic retinal lesions and early visual deficits. Using an unbiased approach in expressing the fast intracellular calcium indicator GCaMP6f in neuronal, glial, and vascular cells of the retina of RS1-deficient male mice, we found that initial cyst formation is paralleled by the appearance of aberrant spontaneous neuroglial signals as early as postnatal day 15, when eyes normally open. These presented as glutamate-driven wavelets of neuronal activity and sporadic radial bursts of activity by Müller glia, spanning all retinal layers and disrupting light-induced signaling. This study confers a role to RS1 beyond its function as an adhesion molecule, identifies an early onset for dysfunction in the course of disease, establishing a potential window for disease diagnosis and therapeutic intervention. SIGNIFICANCE STATEMENT Developmental disorders make it difficult to distinguish pathophysiology due to ongoing disease from pathophysiology due to disrupted development. Here, we investigated a mouse model for X-linked retinoschisis, a well defined monogenic degenerative disease caused by mutations in the Rs1 gene, which codes for the protein retinoschisin. We evaluated the spontaneous activity of explanted retinas lacking retinoschisin at key stages of development using the unbiased approach of ubiquitously expressing GCaMP6f in all retinal neurons, vasculature, and glia. In mice lacking RS1, we found that an array of novel phenotypes, which present around eye opening, are linked to glutamatergic neurotransmission and affect visual processing. These data identify a novel pathophysiology linked to RS1, and define a window where treatments might be best targeted.

The purpose of this study was to investigate the reason that diabetic retinopathy (DR) is delayed from the onset of diabetes (DM) in diabetic mice. To this end, we tested the hypothesis that the deleterious effects of DM are initially tolerated because endogenous antioxidative defense is elevated and thereby confers resistance to oxidative stress-induced death. We found that this was indeed the case in both type 1 DM (T1D) and type 2 DM (T2D) mouse models. The retinal expression of antioxidant defense genes was increased soon after the onset of DM. In addition, ischemia/oxidative stress caused less death in the retinal vasculature of DM versus non-DM mice. Further investigation with T1D mice revealed that protection was transient; it waned as the duration of DM was prolonged. Finally, a loss of protection was associated with the manifestation of both neural and vascular abnormalities that are diagnostic of DR in mice. These observations demonstrate that DM can transiently activate protection from oxidative stress, which is a plausible explanation for the delay in the development of DR from the onset of DM.

PURPOSE: To evaluate retinal function in a family presenting with Jalili syndrome due to a previously unreported variant in CNNM4. METHODS: A family of three sisters with a novel CNNM4 variant, c.482T>C p.(Leu161Pro), and ten visually normal, age-similar controls participated in this study. The subjects underwent detailed dental examinations and comprehensive ophthalmological examinations that included color vision testing, retinal imaging, and electroretinography. Full-field light- and dark-adapted luminance thresholds were obtained, in addition to light- and dark-adapted measures of the pupillary light reflex (PLR; pupil constriction elicited by a flash of light) across a range of stimulus luminance. RESULTS: Clinical findings of cone dysfunction and amelogenesis imperfecta were observed, consistent with Jalili syndrome. Light-adapted ERGs were non-detectable in CNNM4 subjects, whereas dark-adapted ERGs were generally normal. Full-field luminance thresholds were normal under dark-adapted conditions and were elevated, but measurable, under light-adapted conditions. The CNNM4 subjects had large PLRs under dark-adapted conditions and responses near the lower limit of normal, or slightly subnormal, under light-adapted conditions. CONCLUSION: CNNM4 variants can result in Jalili syndrome with cone dystrophy and generally preserved rod function. The PLR may be a useful measure for evaluating cone function in these individuals, as robust cone-mediated PLRs were recordable despite non-detectable light-adapted ERGs.

Introduction Circadian misalignment increased systemic inflammation in sleep experiments and in those performing shift work. Milder degree of circadian misalignment such as day-to-day shift in sleep timing, i.e. sleep variability, was related to inflammation in population studies. Further, other sleep disturbances and glycemic control can contribute to inflammation. This pilot study explored if sleep variability was associated with inflammation in type 2 diabetes (T2D). Methods Subjects included 35 non-shift working T2D patients with and without diabetic retinopathy (DR) who were participating in a clinical study (NCT04547439). Sleep pattern was assessed by 14-day actigraphy, yielding sleep duration and efficiency. Standard deviation of sleep duration across the night was used to represent sleep variability. Sleep apnea severity was assessed by an overnight home monitor. Neuropathy pain, statin use, serum creatinine, low-density lipoprotein (LDL), HbA1C and by high-sensitivity c-reactive protein (hs-CRP) were collected. Spearman’s correlation analyses and multiple regression analysis (using natural-log transformed values) were performed to establish an independent association between sleep variability and hs-CRP. Results Mean (SD) age was 54.3 (6.4) years, 54.3% were female and 62.9% had DR. Median (interquartile range) of sleep variability was 69 (56,84) minutes. Median A1C was 7.5 (6.6, 8.7)% and hs-CRP was 2.4 (1.4, 4.6) mg/L. Higher hs-CRP was significantly associated with higher sleep variability (r=0.342, p=0.04), HbA1c (r=0.431, p=0.01) and LDL (r=0.379, p=0.03), but not with sleep duration, sleep efficiency, sleep apnea severity, DR status or other variables. Multiple regression analysis showed that higher sleep variability (B = 0.91, p=0.034) and higher HbA1c (B = 1.51, p=0.035), but not LDL, contributed to higher hs-CRP. Conclusion Higher sleep variability in non-shift working T2D patients was shown to be independently associated with higher systemic inflammation, conferring higher cardiovascular risk. This data supports the role of even a mild degree of circadian misalignment on systemic inflammation. Further investigations are needed to determine whether sleep intervention to increase sleep regularity can reduce systemic inflammation and improve cardiometabolic health. Support (if any) NEI R01EY029782 The University of Illinois Chicago Center for Clinical and Translational Science, which is supported by the National Center for Advancing Translational Sciences (NCATS), National Institutes of Health, through Grant Award Number UL1TR002003.”

To evaluate spatial and temporal integration across the visual field in individuals with juvenile X-linked retinoschisis (XLRS).Nine subjects with XLRS and 10 visually normal individuals participated. Luminance thresholds were measured at 15 locations along the horizontal visual field meridian. Locations were grouped into four regions for analysis: foveal, parafoveal (2°), perifoveal (5°-10°), and peripheral (10°-60°). For spatial integration measurements, stimulus duration was 100 ms, and size ranged from 0.01 to 2.32 deg2 (Goldmann I-V). For temporal integration measurements, stimulus size was 0.15 deg2 (Goldmann III), and duration ranged from 12 to 800 ms. The effect of stimulus size and duration on the subjects' threshold was described using integration models.Luminance thresholds for the XLRS group were more elevated for small targets (2.0×-12.6×) than for large targets (1.25×-3.2×) compared to controls for all locations. Likewise, thresholds for the XLRS group were more elevated for short durations (6.3×) than for long durations (4.0×) in the fovea and parafovea but were similarly elevated at all durations (2.0×-2.5×) in the perifovea and periphery. For both the size and duration experiments, thresholds measured in the fovea, parafovea, and perifovea of XLRS subjects were highly similar to those measured from the peripheral field of the controls.Spatial and temporal integration characteristics of the XLRS fovea, parafovea, and perifovea are similar to those of the normal periphery. The results also indicate that scaling stimulus size equates thresholds for the XLRS and control subjects throughout the visual field, but scaling duration does not.

Retinitis pigmentosa (RP) is an inherited pigmentary retinal dystrophy where patients experience poor peripheral, night, and eventually central vision. There are statements in the literature which suggest visual acuity loss can progress to total blindness in these patients. This study sought to examine these statements by performing a retrospective analysis of the visual acuity measured in a large cohort of RP patients.The charts of 1,095 RP patients were reviewed in this retrospective cross-sectional analysis. They included all of the RP patients examined by one of the authors (G.A.F.). Patients with sector RP or a delimited form of this disease were not included. The review was focused on the analysis of patients with 20/200 or worse vision in the better-seeing eye (N = 215).We determined that 0.46% of the enrolled patients progressed to no light perception in each eye. Ninety-two percent of the 1,095 patients examined were able to read a visual acuity chart. There were 6.8% who saw only hand motion, count fingers, or light perception.No light perception was measured in only 0.46% of patients. Thus, only a very small number of the RP patients in our cohort progressed to total blindness.

To define relationships among contrast sensitivity (CS), equivalent intrinsic noise (Neq; a measure of noise within the visual pathway), and retinal thickness in X-linked retinoschisis (XLRS).Nine XLRS and 10 visually-normal subjects participated. CS was measured in the presence and absence of luminance noise. These data were fit with a standard model to estimate Neq and sampling efficiency (an estimate of the ability to use stimulus information). Optical coherence tomography images were obtained to quantify outer nuclear layer (ONL+) and outer segment (OS+) thickness. A linear structure-function model was used to describe the relationship between CS and the product of ONL+ and OS+ thickness.CS in the absence of noise (CS0) for the XLRS subjects ranged from normal to as much as 1.5× below the lower limit of normal. Four of the nine subjects with XLRS had abnormally high Neq, whereas two others had sampling efficiency that was borderline abnormal. Log CS0 for the subjects with XLRS was correlated significantly with log Neq (r = -0.78, P = 0.01), but not with log efficiency (r = 0.19, P = 0.63). CS0 and Neq, but not efficiency, conformed to the linear ONL+ × OS+ structure-function model.The XLRS subjects in this study who had elevated internal noise had abnormally low CS; both internal noise and CS fell within the predicted limits of a structure-function model.Internal noise measurements can provide insight into a source of CS loss in some individuals with XLRS.

Purpose To provide a comprehensive analysis of light- and dark-adapted luminance thresholds and their associations with retinal structure in X-linked retinoschisis (XLRS). Methods Nine subjects with XLRS and 10 visually-normal individuals participated. Threshold was measured at 15 locations along the horizontal meridian of the visual field at several adaptation levels (5 × 10-5 to 50 cd/m2) after dark-adaptation. The relationship between threshold and adaptation level across the field was described using a standard "threshold-versus-illuminance" model. Optical coherence tomography images were obtained and segmented to quantify outer nuclear layer (ONL+) and outer segment (OS+) thickness. A linear structure-function model was used to describe the relationship between threshold and the product of ONL+ and OS+ thickness. Results For peripheral field measurements, thresholds were generally normal for most subjects with XLRS. All subjects had perifoveal and parafoveal threshold elevations under dark-adapted and high illuminance conditions, with thresholds at moderate illuminances being closer to normal. For foveal measurements, seven of nine subjects with XLRS had normal dark-adapted thresholds, and all had abnormally elevated high illuminance thresholds. Threshold-versus-illuminance curves in the fovea, parafovea, and perifovea were abnormally steep for subjects with XLRS, appearing similar to the normal peripheral field shape. Under both dark- and light-adapted conditions, threshold was predicted by ONL+ × OS+ thickness at nearly all field locations. Conclusions Threshold elevation in XLRS is complex, depending on both the adaptation level and the visual field location. The pattern of threshold-versus-illuminance suggests that macular function in XLRS is similar to the periphery of controls.

PURPOSE: To evaluate the relationship between microperimetric (MP) sensitivity and retinal thickness measured at co-registered retinal locations in individuals who have mild or no diabetic retinopathy. METHODS: Fifty non-diabetic control subjects and 50 type-2 diabetic subjects participated (25 had no clinically apparent DR [NDR] and 25 had mild nonproliferative DR [MDR]). MP sensitivity was measured at 36 retinal locations that were arranged in three concentric rings centered on the fovea (radii of 3°, 6°, and 12°). Optical coherence tomography (OCT) images were obtained and total retinal thickness (TRT), inner retinal thickness (IRT), and outer retinal thickness (ORT) were quantified from the OCT images at locations that matched the MP measures. Linear quantile mixed models (LQMMs) and linear quantile models (LQMs) were used to compare MP and thickness values for the three subject groups and to quantify structure-function relationships. RESULTS: The statistical models indicated significant TRT and IRT reductions in the NDR and MDR groups, relative to the controls, that were most apparent in the 3° ring. By contrast, ORT was not reduced significantly for either diabetic group. MP sensitivity was reduced significantly within each ring and for both diabetic groups. Despite reductions in both thickness and sensitivity, the structure-function associations were generally weak with borderline statistical significance. For example, a TRT or IRT reduction of approximately 27 μm was predicted to result in approximately 1 dB of MP sensitivity loss for the MDR group (p = 0.03 and 0.05, respectively). CONCLUSIONS: The results support previous findings of early retinal neurodegeneration in diabetics who have NDR or MDR. Interestingly, the structural and functional deficits appear to be only weakly associated, suggesting that mechanisms in addition to retinal thinning underlie the functional defects in early stage DR.

PURPOSE: To investigate the Stargardt disease phenotype associated with an unusually common and “extremely hypomorphic” ABCA4 variant, p.N1868I. METHODS: The charts of 27 patients with p.N1868I on one allele and a severe/deleterious mutation on the other allele were reviewed. Subjective age of onset, best-corrected visual acuity, and stage of disease were recorded for all 27 patients, 18 of whom had multiple visits. When available, fundus photography, spectral domain optical coherence tomography, fundus autofluorescence, full-field electroretinograms, Goldmann visual fields, and fluorescein angiography were included. Five families with multiple affected members were analyzed. RESULTS: The median age at symptom onset was 41.5 years, and 3 p.N1868I patients had not developed visual symptoms as of the most recent eye examination. Median best-corrected visual acuity in the better-seeing eye at baseline was 20/25(−2), and the median duration from symptom onset to legal blindness was 25 years. The five families described in this study demonstrated clinically significant intrafamilial variability, and affected family members who did not share the p.N1868I variant had relatively more severe phenotypes. CONCLUSION: This study demonstrates the consistency of foveal sparing, the variation in age at onset, the intrafamilial variability, and the prognosis with regard to visual acuity in p.N1868I-associated Stargardt disease.

PURPOSE: To define the relationship between abnormalities in the activation phase of cone phototransduction and the oscillatory potentials (OPs) of the light-adapted electroretinogram in diabetics who have mild or no retinopathy. METHODS: Subjects included 20 non-diabetic controls and 40 type-2 diabetics (20 had no clinically-apparent diabetic retinopathy [NDR] and 20 had mild nonproliferative DR). Single flash responses for a series of retinal illuminances were measured under light-adapted conditions using conventional techniques. The a-waves of the responses were fit with a delayed Gaussian model to derive R(mp3) (maximum amplitude of the massed photoreceptor response) and S (phototransduction sensitivity). OPs were extracted from the responses by conventional bandpass filtering. RESULTS: Analysis of variance (ANVOA) indicated that both diabetic groups had significant OP amplitude and S reductions compared to the controls, whereas R(mp3) did not differ significantly among the groups. Although log OP amplitude and log R(mp3) were significantly correlated for the control subjects for each flash retinal illuminance (all r > 0.49, p < 0.03), log OP amplitude and log R(mp3) were not correlated for either diabetic group for any flash retinal illuminance (all r ≤ 0.36, p ≥ 0.13). Log OP amplitude and log S were generally not correlated significantly for the control or diabetic groups. CONCLUSION: OP amplitude losses do not appear to be related to reduced cone sensitivity in early-stage diabetic retinopathy. This suggests that diabetes may separately affect cone function, as evidenced by cone phototransduction sensitivity losses, and inner-retina function, as evidenced by OP amplitude losses.

The flicker electroretinogram (ERG) is typically analyzed in terms of peak-to-trough amplitude and implicit time. However, additional important information may be captured by spectral-domain analysis of the ERG harmonics (responses that occur at multiples of the stimulus frequency). This study describes an approach to analyze the harmonic components of the flicker ERG and its application to patients who have early-stage non-proliferative diabetic retinopathy (NPDR). Of particular interest were the sub-harmonic components occurring at 1.5x and 2.5x the stimulus frequency that produce cycle-to-cycle variation in amplitude termed “period doubling.” Twenty visually-normal subjects, 20 diabetic subjects who have no clinically-apparent retinopathy (NDR), and 20 diabetic subjects who have mild NPDR participated. ERGs were recorded in response to sinusoidal flicker (27–63 Hz) and Fourier analysis was performed to extract fundamental and harmonic response amplitudes. Linear quantile mixed models (LQMMs) were used to compare the amplitude of the response components among the three subject groups. Results indicated that the maximum sub-harmonic amplitude occurred in the stimulus frequency range of 33–38 Hz for all subjects. The LQMMs showed a significant sub-harmonic amplitude reduction for the mild NPDR subjects compared to the controls; sub-harmonic amplitude for the NDR subjects did not differ significantly from the controls. In contrast, the fundamental response did not differ among the groups for stimulus frequencies between 33 and 38 Hz. Modeling these results indicated that subharmonic amplitude loss in mild NPDR subjects may be attributed to attenuated feedback occurring early in the retina, possibly at the synapse of cone photoreceptors and OFF bipolar cells.

PURPOSE: To evaluate three measures of inner-retina function, the pattern electroretinogram (pERG), the photopic negative response (PhNR), and the post-illumination pupil response (PIPR) in diabetics with and without non-proliferative diabetic retinopathy (NPDR). METHODS: Fifteen non-diabetic control subjects and 45 type 2 diabetic subjects participated (15 have no clinically-apparent retinopathy [NDR], 15 have mild NPDR, and 15 have moderate/severe NPDR). The pERG was elicited by a contrast reversing checkerboard pattern and the PhNR was measured in response to a full-field, long-wavelength flash presented against a short-wavelength adapting field. The PIPR was elicited by a full-field, 450 cd/m(2), short-wavelength flash. All responses were recorded and analyzed using conventional techniques. One-way ANOVAs were performed to compare the pERG, PhNR, and PIPR among the control and diabetic groups. RESULTS: ANOVA indicated statistically significant differences among the control and diabetic subjects for all three measures. Holm-Sidak post-hoc comparisons indicated small, non-significant reductions in the pERG (8%), PhNR (8%), and PIPR (10%) for the NDR group compared to the controls (all p > 0.25). In contrast, there were significant reductions in the pERG (35), PhNR (34%), and PIPR (30%) for the mild NPDR group compared to the controls (all p < 0.01). Likewise, there were significant reductions in the pERG (40%), PhNR (32%), and PIPR (32%) for the moderate/severe NPDR group compared to the controls (all p < 0.01). CONCLUSION: Abnormalities of the pERG, PhNR, and PIPR suggest inner-retina neural dysfunction in diabetics who have clinically-apparent vascular abnormalities. Taken together, these measures provide a non-invasive, objective approach to study neural dysfunction in these individuals.

The electroretinogram (ERG) is a noninvasive, objective technique to evaluate retinal function that has become increasingly important in the study of diabetic retinopathy. We summarize the principles and rationale of the ERG, present findings from recent clinical studies that have used the full-field ERG, multifocal ERG, and pattern ERG to evaluate neural dysfunction in patients with diabetes, and weigh the strengths and limitations of the technique as it applies to clinical studies and management of patients with diabetic retinopathy. Taken together, ERG studies have provided convincing evidence for dysfunction of the neural retina in patients with diabetes, including those who have no clinically-apparent retinal vascular abnormalities. Recent full-field ERG findings have pointed to the intriguing possibility that photoreceptor function is abnormal in early-stage disease. Pattern ERG data, in conjunction with recently developed photopic negative response analyses, indicate inner retina dysfunction. In addition, multifocal ERG studies have shown spatially localized neural abnormalities that can predict the location of future microaneurysms. Given the insights provided by the ERG, it is likely to play a growing role in understanding the natural history of neural dysfunction in diabetes, as well as providing an attractive outcome measure for future clinical trials that target neural preservation in diabetic retinopathy.

Purpose To compare electrophysiological and pupillometric responses in subjects with cone-rod dystrophy due to autosomal recessive (AR) PROM1 mutations. Methods Four subjects with AR PROM1 dystrophy and 10 visually normal, age-similar controls participated in this study. Full-field, light- and dark-adapted electroretinograms (ERGs) were obtained using conventional techniques. Full-field, light- and dark-adapted measures of the pupillary light reflex (PLR; pupil constriction elicited by a flash of light) were obtained across a range of stimulus luminance using long- and short-wavelength light. Pupil size as a function of stimulus luminance was described using Naka-Rushton functions to derive Pmax (maximum response) and s (pupil response sensitivity). Results Light-adapted ERGs were non-detectable in all four PROM1 subjects, whereas dark-adapted ERGs were non-detectable in three subjects and markedly attenuated in the fourth. By contrast, each PROM1 subject had light- and dark-adapted PLRs. Pmax ranged from normal to slightly attenuated under all conditions. Light-adapted s was generally normal, with the exception of two subjects who had abnormal s for the long-wavelength stimulus. Dark adapted s was abnormal for each PROM1 subject for the long-wavelength stimulus and ranged from the upper limit of normal to substantially abnormal for the short-wavelength stimulus. Conclusions ERG and PLR comparison showed an unanticipated dichotomy: ERGs were generally non-detectable, whereas PLRs were normal for all PROM1 subjects under select conditions. Differences between the measures may be attributed to distinct spatiotemporal summation/gain characteristics. Translational relevance These data highlight the potential usefulness of pupillometry in cases where the ERG is non-detectable.

PURPOSE: To investigate receptor and post-receptor function in KCNV2 retinopathy (cone dystrophy with supernormal rod ERG), using the pupillary light reflex (PLR) and the electroretinogram (ERG). METHODS: Two unrelated patients (1 male, 1 female) with molecularly confirmed KCNV2 retinopathy underwent full-field two-color pupillometry testing in one eye, with monitoring of the stimulated eye by an infrared digital camera. Pupillometry stimuli consisted of 1-sec duration, short-wavelength (465-nm, blue) and long-wavelength (642-nm, red) stimuli. Pupillometry intensity series were performed under both a dark-adapted condition and a light-adapted condition (on a 0.76-log cd-m(−2) blue background). The transient PLR, defined as the maximum constriction following flash onset, was measured under all conditions. The melanopsin-mediated sustained constriction was measured 5 to 7 sec following flash offset for the highest flash luminance presented in the dark. Both patients were also tested in one eye with the full-field ERG, including a dark-adapted intensity series and ISCEV-standard stimuli. RESULTS: Dark-adapted PLRs were markedly attenuated or extinguished for low luminance stimuli, but the responses to higher luminance blue stimuli were within normal limits. Light-adapted PLRs to blue stimuli were generally within normal limits, exceeding the responses to photopically matched red stimuli. Thus, light-adapted responses were consistent with either rod- or S-cone mediation of the PLR. Melanopsin-mediated sustained PLRs were within normal limits. ERG showed the characteristic findings previously reported in this condition. Cone-mediated ERG responses were markedly decreased in amplitude. Rod-mediated ERG responses were absent for low luminance stimuli (−3 log cd-s-m(−2)), but had normal amplitude for stimuli of −2 log cd-s-m(−2) and above (although none were “supernormal”). The b-wave for dark-adapted ISCEV standard 0.01 stimulus was markedly delayed, whereas the b-wave timing was generally normal for higher flash luminances. CONCLUSIONS: The abnormalities measured by pupillometry have a similar pattern to the outer-retinal abnormalities measured by ERG in KCNV2 retinopathy. These findings, as well as the normal sustained PLR suggests that inner-retinal function may be preserved in KCNV2 retinopathy and highlights the potential for therapies designed to restore outer-retinal function in these individuals.

SIGNIFICANCE The response of the pupil to a flash of light, the pupillary light reflex (PLR), is an important measure in optometry and in other fields of medicine that is typically evaluated by qualitative observation. Here we describe a simple, portable, iPhone-based pupillometer that quantifies the PLR in real time. PURPOSES The purposes of this study were to describe a novel application that records the PLR and to compare its technical capabilities with a laboratory-based infrared (IR) camera system. METHODS Pupil sizes were measured from 15 visually normal subjects (age, 19 to 65 years) using an IR camera system and the Sensitometer test. This test elicits pupillary constriction using the iPhone flash, records pupil size using the camera, and provides measurements in real time. Simultaneous recordings were obtained with the Sensitometer test and IR camera, and two measures were calculated: (1) dark-adapted steady-state pupil size and (2) minimum pupil size after the flash. The PLR was defined as the difference between these two measures. Pupil size was also recorded during the redilation phase after the flash. Bland-Altman analysis was used to assess the limits of agreement between the two methods. RESULTS Statistically significant correlations between the IR and Sensitometer test measures were found for the PLR (r = 0.91, P < .001) and redilation size (r = 0.65, P = .03). Bland-Altman analysis indicated a mean PLR difference of 6% between these two methods. The PLR limit of agreement was 14%, indicating that 95% of subjects are expected to have IR and Sensitometer test measurements that differ by 14% or less. Bland-Altman analysis indicated a mean redilation size difference of 1% between the two methods; the limit of agreement was 5%. CONCLUSIONS There is excellent agreement between pupil responses recorded using the Sensitometer test and IR camera. The Sensitometer test provides a highly promising approach for simple, portable, inexpensive pupillary measurements.

PURPOSE The Boston keratoprosthesis (KPro) is the most commonly used artificial cornea. It has been proven to be successful for severe corneal disease not amenable to keratoplasty. We have observed our patients reporting debilitating glare despite attaining good visual acuities. This motivated us to objectively measure light scatter in eyes with a KPro. METHODS Light scatter was measured in 21 eyes with the Boston type 1 KPro with a VA of 20/150 or better and was compared with 13 healthy control eyes using the Oculus C-Quant device (Arlington, WA). Eyes were also measured using an occluder contact lens. RESULTS Light scatter (quantified as the logS value) was significantly higher in the KPro group than in the control (2.34 ± 0.15 vs. 1.29 ± 0.17, P < 0.001). The polymethylmethacrylate (PMMA) KPro group (16 eyes, logS 2.49 ± 0.19) but not the titanium group (5 eyes, logS 1.87 ± 0.15) had significantly higher light scattering than the control. The use of an occluder contact lens significantly decreased light scatter in eyes with a PMMA backplate (n = 11, logS 1.71 vs. 2.42, P = 0.028). CONCLUSION This study confirms that intraocular light scatter is increased in KPro eyes. Possibly because of its opaque nature, the titanium backplate model seems to produce less light scatter than does the PMMA model. Occluder contact lenses reduced light scatter significantly in the PMMA KPro and could be a treatment option for symptomatic patients.

The International Society for Clinical Electrophysiology of Vision (ISCEV) Standard for full-field electroretinography (ERG) describes a minimum procedure, but encourages more extensive testing. This ISCEV extended protocol describes an extension to the ERG Standard, namely the photopic negative response (PhNR) of the light-adapted flash ERG, as a well-established technique that is broadly accepted by experts in the field. The PhNR is a slow negative-going wave after the b-wave that provides information about the function of retinal ganglion cells and their axons. The PhNR can be reduced in disorders that affect the innermost retina, including glaucoma and other forms of optic neuropathy. This document, based on existing literature, provides a protocol for recording and analyzing the PhNR in response to a brief flash. The protocol includes full-field stimulation, a frequency bandwidth of the recording in which the lower limit does not exceed 0.3 Hz, and a spectrally narrowband stimulus, specifically, a red flash on a rod saturating blue background. Suggested flash strengths cover a range up to and including the minimum required to elicit a maximum amplitude PhNR. This extended protocol for recording the PhNR provides a simple test of generalized retinal ganglion cell function that could be added to standard ERG testing.

Purpose To determine whether dilation status has a clinically meaningful effect on sensitivity in normal subjects undergoing two-color dark-adapted perimetry, which can be useful to assess rod function. Methods A perimeter measured naturally and pharmacologically dilated scotopic sensitivities using a test grid consisting of 16 points across the horizontal meridian ranging from 60° temporal to 45° nasal using cyan (500 nm wavelength) or red (650 nm wavelength) stimuli. The primary outcome was average overall sensitivity based on dilation status, which was compared using a linear mixed effect model for each color stimuli. A difference of 2 dB or more was considered clinically significant. Results Twenty-nine eyes from 15 subjects (nine female) ages 23 to 63 with no known retinal pathology were included. Pharmacologically dilated eyes were 0.54 dB (95% confidence interval [CI], 0.05 dB to 1.03 dB; P = 0.032) more sensitive to a red stimulus than naturally dilated eyes, but this was not statistically significant after correction for multiple comparisons. Pharmacologically dilated eyes were 0.03 dB (95% CI, −0.20 dB to 0.14 dB; P = 0.734) less sensitive to a cyan stimulus compared to naturally dilated eyes. Conclusions These findings show no clinically significant differences in sensitivity of scotopic perimetry in eyes without retinal pathology based on dilation status for both cyan and red stimuli. Translational Relevance In this study, pharmacological dilation did not have a clinically meaningful effect on sensitivity, suggesting that this is not necessary when using two-color dark-adapted perimetry to assess for rod function.

Background: Intrinsically photosensitive retinal ganglion cells (ipRGCs) control non-visual light responses (e.g. pupillary light reflex and circadian entrainment). Patients with diabetic retinopathy (DR) show reduced ipRGC function, as inferred by abnormalities in the post illumination pupil response (PIPR). We explored whether ipRGC function in DR is associated with circadian outputs and sleep/wake behavior. Methods: Forty-five participants (15 without diabetes, 15 with type 2 diabetes (T2D) and no DR, 15 with T2D and DR) participated. ipRGC function was inferred from the PIPR (pupil size following stimulus offset). Circadian outputs were melatonin amplitude (overnight urinary 6-sulfatoxymelatonin (aMT6s)) and timing (dim light melatonin onset (DLMO)), and evening salivary cortisol levels. Sleep/wake patterns were measured with wrist actigraphy and insomnia symptoms were assessed subjectively. Results: Patients with T2D and DR had smaller PIPR and lower urinary aMT6s than other groups (p

PURPOSE: To determine the relationship between contrast sensitivity (CS) and outer-retina thickness (ORT) in diabetics who have minimal or no diabetic retinopathy (DR). METHODS: Twenty non-diabetic control subjects and 40 type-2 diabetic subjects participated (20 had no clinically apparent DR [NDR] and 20 had mild nonproliferative DR [NPDR]). No subject had a history of treatment for macular edema. Letter CS, microperimetric (MP) sensitivity, and visual acuity (VA) were measured. Letter CS and MP measurements were performed over the central 6° of the visual field. Spectral domain optical coherence tomography (SD-OCT) images were obtained at corresponding locations, outer retina thickness was quantified, and structure-function relationships were evaluated. RESULTS: Analysis of variance indicated significant letter CS differences among the groups (p < 0.001). Letter CS was reduced significantly for the mild NPDR group (p < 0.001; 33% reduction), but not the NDR group (p = 0.08). There were no significant differences in MP sensitivity or ORT among the groups (both p > 0.10). Nevertheless, Hoeffding’s D tests indicated significant associations between ORT and letter CS (p < 0.001) and between ORT and MP sensitivity for the mild NPDR group (p = 0.01). VA was not significantly associated with ORT for either diabetic group (both p > 0.49). CONCLUSIONS: Outer-retina thickness is associated with letter CS and MP sensitivity, but not VA, in mild NPDR. This finding highlights the usefulness of simple letter CS measures and suggests neural dysfunction can occur in the absence of marked structural abnormalities in early stage DR.

Background: Intrinsically photosensitive retinal ganglion cells (ipRGCs) control the pupillary light reflex (PLR) and synchronize sleep-wake cycles, melatonin secretion, and metabolic processes to the 24-h day. PLR abnormalities in diabetic retinopathy (DR) suggest ipRGC dysfunction. We explored whether ipRGC dysfunction in DR is associated with impaired sleep, circadian rhythms and metabolic functioning. Methods: Healthy controls (n=6), type 2 diabetes (T2D) without DR (n=8), or T2D with at least moderate DR (n=11) participated. PLR inferred ipRGC function, HbA1c, and nocturnal urinary 6-sulfatoxymelatonin (aMT6s/creatinine ratio) were measured. Sleep was recorded by 7-day actigraphy. Dim light melatonin onset (DLMO) was assessed by sampling saliva in the 7 hours before self-reported bedtime. Results: Mean age was 54.6±5.4 yr. The relative PLR was significantly smaller in T2D-DR (control vs. T2D-noDR vs. T2D-DR: 0.32(0.10) vs. 0.26 (0.09) vs. 0.13 (0.11), p=0.003). Nocturnal aMT6s [8.3 (3.1) vs. 14.6 (14.3) vs. 1.9 (2.1) ng/mg, p=0.001] was significantly lower in T2D-DR. Sleep was more disturbed in T2D-DR than others as reflected by higher wake time after sleep onset (p=0.024), higher fragmentation index (p=0.007) and lower sleep efficiency (p=0.030). HbA1c was similar between T2D groups. T2D-DR were more likely to have no detectable rise of salivary melatonin in the evening (normal 16% vs. DM-noDR 14% vs. DM-DR 67%, p=0.049). Smaller PLRs correlated with lower aMT6s (r=0.652, p=0.001). Among T2D, lower aMT6s and smaller PLR associated with lower sleep efficiency (p=0.029-0.046) and more fragmented sleep (p=0.028-0.066). There was no relationship between PLR or aMT6s with HbA1c in T2D. PLR was smaller in those without vs. with DMLO [0.11 (0.09) vs. 0.29 (0.09), p Conclusion: T2D with DR had dysregulated melatonin rhythm and disrupted sleep, which significantly correlated with the degree of ipRGC dysfunction. Disclosure S. Reutrakul: None. J.C. Park: None. F. Chau: None. T. Baynard: None. M. Priyadarshini: None. S. Crowley: None. J. McAnany: None. Funding University of Illinois at Chicago

Purpose To define characteristic ocular features in a group of patients with autosomal recessive (AR) PROM1 cone-rod dystrophy (CRD). Methods Three males and one female from three unrelated families were first seen at the ages of 15 to 22 years and diagnosed with CRD. Clinical testing available for review included full-field electroretinogram (ERG) in three patients, as well as near-infrared autofluorescence (NIR-AF), spectral-domain optical coherence tomography (SD-OCT), and color fundus photography in all four patients. Whole exome sequencing (WES) was performed on all cases, and whole genome sequencing (WGS) was performed in two families. Results WES found compound heterozygous PROM1 variants in one isolated male, plus heterozygous variants in the remaining patients. WGS uncovered deleterious PROM1 variants in these two families. ERG showed markedly reduced cone-isolated amplitudes and variably reduced rod-isolated amplitudes. The dark-adapted combined rod and cone responses demonstrated notably reduced a-wave amplitudes and moderately reduced b-waves, and the resultant waveform resembled the normal rod-isolated response. On fundus examination, oval-shaped macular lesions were observed, as were several small, circular hypoautofluorescent lesions within the posterior pole on NIR-AF. Three patients showed extramacular circular atrophic lesions. Conclusions The autofluorescence changes, peripheral retinal abnormalities, and ERG findings have not been emphasized in previous reports of AR PROM1, but they became a recognizable phenotype in this cohort of patients. A similar constellation of findings may be observed in CRD due to CDHR1, a functionally related gene. The pattern of abnormalities reported herein may help to focus genetic screening in patients with these findings.

To compare measurements of the full-field photopic negative response (PhNR), as well as intra-subject variation in the PhNR, using time and time–frequency domain analyses. Full-field ERGs were recorded from 20 normally sighted subjects (aged 24–65 years) elicited by a long-wavelength pulse (3 cd s m−2) presented against a short-wavelength adapting field (12.5 cd m−2). Three to 10 waveforms were obtained from each subject, and each waveform was analyzed using standard time domain analyses of the PhNR, as well as a discrete wavelet transform (DWT) to extract time–frequency components that correspond to the PhNR. Three different measures of the PhNR were derived and compared: (1) amplitude at the PhNR trough; (2) amplitude at 72 ms following stimulus onset; (3) energy in the 11 Hz, 60–120 ms DWT frequency bin that corresponds to the PhNR. In addition, the effect of normalizing the PhNR by the b-wave was evaluated for each of the measures. Coefficients of variation (CVs) were computed for each definition to evaluate intra-subject variation. PhNR amplitudes measured at the trough and at 72 ms were significantly correlated (r = 0.88, p

To evaluate rod-isolated, cone-isolated, and combined rod and cone flicker electroretinograms (ERGs) as a possible means to identify electrophysiological abnormalities in carriers of X-linked retinoschisis (XLRS). Full-field ERGs were recorded from six carriers of XLRS (aged 34–66 years) and eight normally sighted subjects (aged 27–59 years) under rod-isolated (ERGR), cone-isolated (ERGC), and combined rod and cone (ERGR+C) conditions. ERGs were obtained using a four-primary LED-based ganzfeld photostimulator and standard recording techniques. The four primaries were modulated sinusoidally in phase to achieve combined rod and cone activation (ERGR+C) or in different phases to achieve ERGR and ERGC by means of triple silent substitution. After 30 min of dark adaptation, 8- and 15-Hz ERGR, ERGC, and ERGR+C responses were obtained at a mean luminance level of 24 scot. cd/m2. Standard ISCEV ERGs were also obtained from each subject. The ISCEV and 15-Hz flicker ERGs were generally within the normal range for the carriers. The 8-Hz ERGR, ERGC, and ERGR+C amplitudes were also generally normal. In contrast, the carriers had ERGR, ERGC, and ERGR+C timing abnormalities, with phase advances beyond the range of normal for the ERGR (four carriers), ERGC (four carriers), and ERGR+C (three carriers). Only one carrier had normal 8-Hz responses under all conditions. The 8-Hz ERG timing abnormalities in five of six carriers indicate that retinal function is not necessarily normal in carriers of XLRS. The 8-Hz flicker ERG may be useful for studying retinal function in these individuals.

Purpose To evaluate the nature and extent of functional abnormality in X-linked retinoschisis (XLRS) by comparing three dark-adapted, full-field measures: the electroretinogram (ERG), pupillary light reflex (PLR), and luminance threshold. Methods ERGs, PLRs (pupil constriction due to light stimulation), and luminance thresholds were measured from seven XLRS subjects and from 10 normally sighted, age-similar controls. ERGs and PLRs were obtained for a range of flash strengths, and these data were fit with Naka–Rushton functions to derive the maximum saturated b-wave (Vmax) and PLR (Pmax) amplitudes. Additionally, semi-saturation constants were obtained for the b-wave (σ) and PLR (s). Values of 1/σ and 1/s provide sensitivity measures. Full-field, dark-adapted luminance thresholds were measured using 465-nm and 642-nm flash stimuli. Results V max and 1/σ were significantly reduced in XLRS compared to the controls (both t ≥ 5.33, P < 0.001). In comparison, Pmax was normal in the XLRS subjects (t = 1.39, P = 0.19), but 1/s was reduced (t = 7.84, P < 0.001). Luminance thresholds for the control and XLRS groups did not differ significantly (F = 3.57, P = 0.08). Comparisons among measures indicated that pupil sensitivity was correlated with luminance threshold for the long- and short-wavelength stimuli (both, r ≥ 0.77, P ≤ 0.04). Correlations among all other measures were not statistically significant. Conclusions The results indicate that the presumed bipolar cell dysfunction in XLRS, indicated by b-wave abnormalities, has complex downstream effects: Dark-adapted luminance threshold and maximum pupil responses are not significantly affected, but pupil sensitivity is reduced.

Purpose To define the nature and extent of temporal frequency abnormalities in diabetics who have mild or no nonproliferative diabetic retinopathy (NPDR) by using the flicker electroretinogram (ERG). Methods Light-adapted flicker ERGs were recorded from 20 diabetics who have no clinically apparent retinopathy, 20 diabetics who have mild NPDR, and 20 nondiabetic, age-equivalent controls. ERGs were elicited by full-field sinusoidal flicker across the temporal frequency range of 6 to 100 Hz and were recorded using conventional techniques. The amplitude and phase of the fundamental and harmonic response components were derived by Fourier analysis and compared among the groups. Results Analysis of variance indicated that compared with the controls, both patient groups had significant amplitude reductions of the fundamental ERG component for temporal frequencies greater than 56 Hz (all P ≤ 0.03). Modeling the amplitude measurements indicated that both patient groups had significant reductions in the high-frequency response cutoff. Response phase, however, did not differ significantly among the groups at any frequency. The amplitude and phase of the high-frequency harmonics (32-96 Hz) of the patients' responses to a low-frequency stimulus (16 Hz) were normal over the temporal frequency range that the fundamental response was abnormal. Conclusions Taken together, the diabetics' fundamental amplitude attenuation for rapid flicker combined with their normal high-frequency harmonic responses generated by slow flicker suggest that the likely site of the abnormal temporal filtering occurs prior to the nonlinearity that generates the harmonic components of the ERG, implicating a photoreceptor origin.

Purpose: To assess the nature and extent of non-linear processes in pupil responses using rod- and cone-isolating visual beat stimuli. Methods: A four-primary photostimulating method based on the principle of silent substitution was implemented to generate rod or cone isolating and combined sinusoidal stimuli at a single component frequency (1, 4, 5, 8, or 9 Hz) or a 1 Hz beat frequency (frequency pairs: 4 + 5, 8 + 9 Hz). The component frequencies were chosen to minimize the melanopsin photoresponse of intrinsically photosensitive retinal ganglion cells (ipRGCs) such that the pupil response was primarily driven by outer retinal photoreceptor inputs. Full-field (Ganzfeld) pupil responses and electroretinograms (ERGs) were recorded to the same stimuli at two mesopic light levels (−0.9 and 0 log cd/m2). Fourier analysis was used to derive the amplitudes and phases of the pupil and ERG responses. Results: For the beat frequency condition, when modulation was restricted to the same photoreceptor type at the higher mesopic level (0 log cd/m2), there was a pronounced pupil response to the 1 Hz beat frequency with the 4 + 5 Hz frequency pair and rare beat responses for the 8 + 9 Hz frequency pair. At the lower mesopic level there were few and inconsistent beat responses. When one component modulated the rod excitation and the other component modulated the cone excitation, responses to the beat frequency were rare and lower than the 1 Hz component frequency condition responses. These results were confirmed by ERG recordings. Conclusions: There is non-linearity in both the pupil response and electroretinogram to rod and cone inputs at mesopic light levels. The presence of a beat response for modulation components restricted to a single photoreceptor type, but not for components with cross-photoreceptor types, indicates that the location of a non-linear process in the pupil pathway occurs at a retinal site earlier than where the rod and cone signals are combined, that is, at the photoreceptor level. Fil: Barrionuevo, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentina Fil: McAnany, J. Jason. University of Illinois; Estados Unidos Fil: Zele, Andrew J.. Queensland University of Technology; Australia Fil: Cao, Dingcai. University of Illinois; Estados Unidos

To evaluate retinal dysfunction in diabetic patients who have mild or no nonproliferative diabetic retinopathy (DR) using the high-frequency flicker electroretinogram.Light-adapted flicker electroretinograms were recorded from 15 diabetic patients who have no clinically apparent retinopathy, 15 diabetic patients who have mild nonproliferative DR, and 15 nondiabetic, age-equivalent controls. Electroretinograms were elicited by full-field flicker at 2 temporal frequencies, 31.25 and 62.5 Hz, and were recorded using conventional techniques. Amplitude and timing of the flicker responses were compared among the groups and correlated with clinical characteristics including age, acuity, disease duration, and HbA1c.The 31.25-Hz flicker amplitude was slightly, but nonsignificantly, smaller for subjects with no DR and mild nonproliferative DR , compared with the control group (both t1.38, P0.31); small, nonsignificant response delays for both patient groups were also observed (both t1.57, P0.12). By contrast, there were significant amplitude reductions for the 62.5-Hz flicker stimulus: mean amplitude was reduced by 32% for subjects with no DR and by 41% for subjects with mild nonproliferative DR (both t2.92 and P0.01). Response timing at 62.5 Hz did not differ significantly from control for either group (both t1.2 and P0.39). Electroretinogram amplitude and timing were not correlated significantly with clinical characteristics.The 62.5-Hz flicker electroretinogram is useful for evaluating retinal dysfunction in diabetic patients who have mild or no DR because this response can be significantly reduced. Attenuation of the high-frequency flicker electroretinogram, which is primarily generated by bipolar cells, suggests a relatively early retinal site of neural dysfunction.

Oxidative stress is a pathogenic feature in vitreoretinal disease. However, the ability of the inner retina to manage metabolic waste and oxidative stress is unknown. Proteomic analysis of antioxidants in the human vitreous, the extracellular matrix opposing the inner retina, identified superoxide dismutase-3 (SOD3) that localized to a unique matrix structure in the vitreous base and cortex. To determine the role of SOD3, Sod3-/- mice underwent histological and clinical phenotyping. Although the eyes were structurally normal, at the vitreoretinal interface Sod3-/- mice demonstrated higher levels of 3-nitrotyrosine, a key marker of oxidative stress. Pattern electroretinography also showed physiological signaling abnormalities within the inner retina. Vitreous biopsies and epiretinal membranes collected from patients with diabetic vitreoretinopathy (DVR) and a mouse model of DVR showed significantly higher levels of nitrates and/or 3-nitrotyrosine oxidative stress biomarkers suggestive of SOD3 dysfunction. This study analyzes the molecular pathways that regulate oxidative stress in human vitreous substructures. The absence or dysregulation of the SOD3 antioxidant at the vitreous base and cortex results in increased oxidative stress and tissue damage to the inner retina, which may underlie DVR pathogenesis and other vitreoretinal diseases.

Purpose To compare differences in contrast threshold among individual Sloan letters presented in additive white luminance noise and in the absence of noise. Methods Contrast threshold for letter identification was measured for three visually normal subjects (aged 22, 25, and 34 years) using letters from the Sloan set (C, D, H, K, N, O, R, S, V, and Z). The letter size was equivalent to 1.5 logMAR (logarithm of the minimum angle of resolution), and the letters were either unfiltered or band-pass filtered to limit the object frequency content (cycles per letter) to a one-octave wide band centered at 1.25, 2.5, 5, and 10 cycles per letter. Letters were presented for an unlimited duration against a uniform adapting field or in the presence of additive white luminance noise. Contrast threshold for each letter was determined using a 10-alternative forced-choice interleaved staircase procedure. Results For standard unfiltered Sloan letters presented against a uniform field, contrast threshold for individual letters differed by as much as a factor of 1.5, consistent with a previous report. When measured in luminance noise, the individual letters differed by as much as a factor of 1.8. Band-pass filtering the letters to include only low object frequencies increased the differences in contrast threshold among the individual letters (about a factor of 3) compared with unfiltered letters and letters filtered into high object frequency bands. Conclusions The addition of white luminance noise had relatively small effects on interletter contrast threshold differences, whereas band-pass filtering had large effects on interletter threshold differences, greatly increasing variation among the letters that contained only low object frequencies. Letters that contain only high object frequencies may be useful in the design of letter charts because the interletter threshold differences are relatively small for these optotypes and the object frequency information mediating identification is known.

Purpose. Diabetes is known to cause alterations in retinal microvasculature and tissue that progressively lead to visual impairment. Optical coherence tomography (OCT) is useful for assessment of total retinal thickening due to diabetic macular edema (DME). In the current study, we determined associations between visual acuity (VA) and retinal layer thickness, reflectance, and interface disruption derived from enface OCT images in subjects with and without DME. Materials and Methods. Best corrected VA was measured and high-density OCT volume scans were acquired in 149 diabetic subjects. A previously established image segmentation method identified retinal layer interfaces and locations of visually indiscernible (disrupted) interfaces. Enface thickness maps and reflectance images of the nerve fiber layer (NFL), combined ganglion cell and inner plexiform layer (GCLIPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor outer segment layer (OSL), and retinal pigment epithelium (RPE) were generated in the central macular subfield. The associations among VA and retinal layer metrics were determined by multivariate linear regressions after adjusting for covariates (age, sex, race, HbA1c, diabetes type, and duration) and correcting for multiple comparisons. Results. In DME subjects, increased GCLIPL and OPL thickness and decreased OSL thickness were associated with reduced VA. Furthermore, increased NFL reflectance and decreased OSL reflectance were associated with reduced VA. Additionally, increased areas of INL and ONL interface disruptions were associated with reduced VA. In subjects without DME, increased INL thickness was associated with reduced VA, whereas in subjects without DME but with previous antivascular endothelium growth factor treatment, thickening of OPL was associated with reduced VA. Conclusions. Alterations in retinal layer thickness and reflectance metrics derived from enface OCT images were associated with reduced VA with and without presence of DME, suggestive of their potential for monitoring development, progression, and treatment of DME.

To evaluate rod and cone contributions to the dark-adapted 15-Hz flicker electroretinogram (ERG) across a broad range of stimulus luminances by comparing rod-isolating (ERGR), cone-isolating (ERGC), and non-receptor-specific (ERGR+C) responses.Dark-adapted, full-field 15-Hz ERGs were obtained from four normally sighted subjects (ages 29-36 years) using a four-primary LED-based stimulating system. The primaries were either modulated sinusoidally in phase (ERGR+C) or were modulated in counter-phase to achieve rod isolation (ERGR) or cone isolation (ERGC) by means of triple silent substitution. Measurements were made for a broad range of luminances (-2.5 to 1.8 log scot. cd/m(2) in 0.2 log unit steps). Fourier analysis was used to obtain the amplitude and phase of the fundamental response component at each stimulus luminance.Stimulus luminance had different effects on response amplitudes and phases under the three paradigms. Specifically, ERGC amplitude and phase increased monotonically as luminance increased. The effects on ERGR+C and ERGR were complex: ERGR+C and ERGR amplitude was small and the phase decreased for low luminances, whereas amplitude and phase increased sharply at moderate luminances. For high luminances, ERGR+C amplitude and phase increased, whereas ERGR amplitude decreased and phase was approximately constant.At low luminances, the ERGR+C and ERGR functions can be attributed to interactions between two rod pathways. At high luminances, the functions can be accounted for by interactions between rod and cone pathways (ERGR+C) or rod insensitivity (ERGR). The ERGR paradigm minimizes cone intrusion, permitting assessment of rod function over a large range of luminance levels.

To evaluate the relationship between electrophysiological measures of retinal ganglion cell (RGC) function in patients who have idiopathic intracranial hypertension (IIH).The pattern electroretinogram (pERG) and photopic negative response (PhNR) were recorded from 11 IIH patients and 11 age-similar controls. The pERG was elicited by a contrast-reversing checkerboard. The PhNR, a slow negative component following the flash ERG b-wave, was recorded in response to a long-wavelength flash presented against a short-wavelength adapting field. The PhNR was elicited using full-field (ffPhNR) and focal macular (fPhNR) stimuli. Additionally, Humphrey visual field mean deviation (HVF MD) was measured and ganglion cell complex volume (GCCV) was obtained by optical coherence tomography.The ffPhNR, fPhNR, and pERG amplitudes were outside of the normal range in 45, 9, and 45% of IIH patients, respectively. However, only mean ffPhNR amplitude was reduced significantly in the patients compared to controls (p 0.01). The pERG amplitude correlated significantly with HVF MD and GCCV (both r 0.65, p 0.05). There were associations between ffPhNR amplitude and HVF MD (r = 0.58, p = 0.06) and with GCCV (r = 0.52, p = 0.10), but these did not reach statistical significance. fPhNR amplitude was not correlated significantly with HVF MD or GCCV (both r 0.40, p 0.20).Although the fPhNR is generally normal in IIH, other electrophysiological measures of RGC function, the ffPhNR and pERG, are abnormal in some patients. These measures provide complementary information regarding RGC dysfunction in these individuals.

This study evaluated the extent to which different types of luminance noise can be used to target selectively the inferred magnocellular (MC) and parvocellular (PC) visual pathways. Letter contrast sensitivity (CS) was measured for three visually normal subjects for letters of different size (0.8°-5.3°) under established paradigms intended to target the MC pathway (steady-pedestal paradigm) and PC pathway (pulsed-pedestal paradigm). Results obtained under these paradigms were compared to those obtained in asynchronous static noise (a field of unchanging luminance noise) and asynchronous dynamic noise (a field of randomly changing luminance noise). CS was measured for letters that were high- and low-pass filtered using a range of filter cutoffs to quantify the object frequency information (cycles per letter) mediating letter identification, which was used as an index of the pathway mediating CS. A follow-up experiment was performed to determine the range of letter duration over which MC and PC pathway CS can be targeted. Analysis of variance indicated that the object frequencies measured under the static noise and steady-pedestal paradigms did not differ significantly (p ≥ 0.065), but differed considerably from those measured under the dynamic noise (both p < 0.001) and pulsed-pedestal (both p < 0.001) paradigms. The object frequencies mediating letter identification increased as duration increased under the steady-pedestal paradigm, but were independent of target duration (50-800 ms) under the pulsed-pedestal paradigm, in static noise, and in dynamic noise. These data suggest that the spatiotemporal characteristics of noise can be manipulated to target the inferred MC (static noise) and PC (dynamic noise) pathways. The results also suggest that CS within these pathways can be measured at long stimulus durations, which has potential importance in the design of future clinical CS tests.

This study compared the effects of exposure duration on letter and grating targets in a visual acuity (VA) task and determined if the broadband nature of letters accounts for their temporal summation characteristics. Log MAR (minimum angle of resolution) VA of five individuals (ages 25–36) was measured with a set of tumbling E optotypes for durations of 24ms to 1s. The Es were either unfiltered or low-pass filtered to determine the object frequencies (cycles per letter; cplE) mediating VA. The retinal frequencies mediating VA for the unfiltered E (cycles per degree; cpdE) were derived from the ratio of cplE to MAR. Values of cpdE were compared to threshold retinal frequency obtained with band-limited Es and gratings to further evaluate the effects of stimulus bandwidth. Both log MAR and log cplE for the unfiltered E decreased as duration increased up to approximately 260ms, and were constant thereafter. VA also improved for gratings and band-pass filtered Es, but over a shorter time course (approximately 150ms). The effect of duration on VA for the broadband E, Gabor, and band-pass filtered E was similar when the object frequencies mediating VA were included in the definition of VA by converting to cpdE. The results indicate that the pattern of temporal integration for the tumbling E is related to its broadband nature. Band-pass filtered letters can simplify the interpretation of VA because the object frequency information mediating VA is known exactly and is independent of duration and letter size.

To investigate psychophysical thresholds in Stargardt disease with the full-field stimulus test (FST).Visual acuity, spectral domain optical coherence tomography, full-field electroretinogram, and FST measurements were made in 1 eye of 24 patients with Stargardt disease. Dark-adapted rod FST thresholds were measured with short-wavelength stimuli, and cone FST thresholds were obtained from the cone plateau phase of dark adaptation using long-wavelength stimuli. Correlation coefficients were calculated for FST thresholds versus macular thickness, visual acuity, and electroretinogram amplitudes.The Stargardt disease patients' FST cone thresholds correlated significantly with visual acuity, macular thickness, and electroretinogram cone response amplitudes (all P0.01). The patients' FST rod thresholds correlated with electroretinogram rod response amplitudes (P0.01) but not macular thickness (P = 0.05). All patients with Stargardt disease with flecks confined to the macula, and most of the patients with flecks extending outside of the macula had normal FST thresholds. All patients with extramacular atrophic changes had elevated FST cone thresholds and most had elevated FST rod thresholds.Full-field stimulus test rod and cone threshold elevation in patients with Stargardt disease correlated well with measures of structure and function, as well as ophthalmoscopic retinal appearance. The Full-field stimulus test appears to be a useful tool for assessing rod and cone function in Stargardt disease.

PURPOSE To evaluate dark-adapted retinal sensitivity in patients with Stargardt disease (STGD1) using a modified MP-1 microperimeter and to compare the sensitivity loss with structural changes observed using spectral domain optical coherence tomography and confocal scanning laser ophthalmoscope infrared imaging. METHODS Twelve STGD1 patients and 10 normally sighted controls participated. Dark-adapted mean sensitivity (MS) was obtained using a MP-1 microperimeter. Additionally, MS percent difference between the patients and the controls was obtained. Sensitivity results were superimposed on confocal scanning laser ophthalmoscope infrared images and compared with corresponding spectral domain optical coherence tomography scans. RESULTS Dark-adapted MS ± standard deviation was 8.34 ± 1.54 dB for the controls and 3.68 ± 1.74 dB for STGD1 patients (P < 0.001). There was a significant reduction in MS of 24.0% in these patients. Sensitivity reductions were observed in areas that showed changes on confocal scanning laser ophthalmoscope infrared images and on spectral domain optical coherence tomography, including disorganizational loss of the retinal pigment epithelium, and abnormal photoreceptor inner segment ellipsoid and external limiting membrane reflectance bands. CONCLUSION With topographical accuracy, dark-adapted MS measurements can be made in STGD1 patients and controls using the MP-1 microperimeter. Sensitivity loss is associated with structural changes. This finding can be useful for the determination of optimal areas for potential improvement of retinal function in patients with Stargardt disease.

To evaluate the nature and extent of changes in the fundamental and harmonic components of the 31-Hz flicker electroretinogram (ERG) during light adaptation. Full-field ERGs were recorded from five visually normal subjects (ages 21–60 years). Following 30 min of dark adaptation, the subjects were exposed to a uniform adapting field of 50 cd/m2. The field, which was presented for approximately 15 min, was intermittently modulated sinusoidally at 31.25 Hz. The ERG was recorded during the sinusoidal modulation, and Fourier analysis was used to obtain the amplitude and phase of the fundamental (F), second (2F), and third (3F) harmonic response components. F amplitude increased by almost a factor of two over approximately 6 min (time constant, τ, of 3.0 min). The 2F amplitude increased by a smaller amount, a factor of 1.4, and the time-course was approximately eight times faster than that of F (τ = 0.4 min). The 3F amplitude increased by a factor of 4.6, an increase that was larger than F or 2F, with a time-course that was between that of F and 2F (τ = 1.4 min). F phase was unaffected by light adaptation, whereas the 2F and 3F phases both increased by approximately 45° over similar time-courses (τ = 2.0 min). Light adaptation had different effects on the fundamental, second, and third harmonic components of the 31-Hz flicker ERG, which resulted in a change in waveform shape during light adaptation. The previously reported flicker ERG amplitude growth is driven primarily, but not entirely, by changes in the fundamental.

Diabetic retinopathy (DR) is the most frequent cause of vision loss among working-age adults in the Western world.1 DR has classically been considered a microcirculatory disease of the retina and the clinical signs of DR primarily involve structural changes of the retinal vasculature, including microaneurysms, hemorrhages, and vascular occlusions. These vascular abnormalities can result in functional losses, particularly in cases of edema, capillary non-perfusion, and retinal detachment. Visual acuity (VA), which is the most common measure of visual function in patients with DR, can be reduced when the vascular abnormalities affect the central macula. In addition to the well-documented vascular changes, neural and optical abnormalities have also been described in patients with DR. Apoptosis has been reported in the retinal ganglion cell layer in these patients2,3 and the loss of cells results in a reduction of the retinal nerve fiber layer thickness.4,5 Furthermore, neural function may be indirectly affected by abnormalities in retinal glia that have been reported in animal models of DR including reactive gliosis,6 impaired neurotransmitter uptake,7 and altered metabolism.8 In addition to neural dysfunction, diabetic patients can have optical defects that include structural changes of the cornea and lens9 and elevated higher-order optical aberrations (HOA).10 The neural abnormalities can alter retinal signal processing and optical abnormalities can degrade the retinal image by reducing contrast and introducing phase shifts. These neural and optical abnormalities may lead to an elevated level of blur within the visual system, which is expected to adversely impact visual function. However, the relative contribution of optical and neural blur to VA loss in patients with DR is not well understood at present. One approach to evaluate the relative contributions of these sources of blur is to measure the total amount of blur within the visual system (i.e. “equivalent intrinsic blur”)11, 12 and then partition the equivalent intrinsic blur measurement into optical and neural components.13 An estimate of optical blur can be derived from the optical point spread function (PSF), whereas neural blur can be defined as the blur that remains once the contributions of optical blur to equivalent intrinsic blur are accounted for. Thus, this definition of neural blur includes neural factors such as apoptosis, as well as factors that indirectly affect neural function such as glial abnormalities, ischemia, microaneurysms, and edema. The purpose of the present study was to characterize the relationships among VA, equivalent intrinsic blur, optical blur, and neural blur in patients with proliferative diabetic retinopathy (PDR). Measurements obtained from patients with PDR were compared to a group of normally-sighted individuals to determine the extent to which equivalent intrinsic blur, optical blur, and neural blur differ from normal.