The relation of the multifocal electroretinographic response to macular layer volume.

PURPOSE: To determine the association of the multifocal electroretinographic (mfERG) response amplitude with the volumes of the inner, postreceptor, and photoreceptor retinal layers in the region stimulated by each mfERG element. METHODS: Sixteen healthy, young adult control subjects were studied. Each of the 103 hexagonal elements of the standard, scaled mfERG were aligned, where possible, with patches of retina imaged using optical coherence tomography. Stimuli falling on the fovea and on the optic nerve head were excluded. Linear mixed-effects modeling was then used to derive estimated coefficients (voltage/volume) for the mfERG response throughout the full 80 ms standard epoch. The resulting predicted response amplitudes originating in each layer were then compared to pharmacologically "dissected" mfERGs obtained from other studies in monkey eyes. RESULTS: Across the duration of the response, the amplitude of the modeled contribution from (1) the inner retina was small-to-modest, (2) the postreceptor retina was larger and contained two prominent peaks, and (3) the photoreceptor response was the largest and most closely paralleled the overall (i.e., intact) response, including late-appearing oscillations. The significance of each layer's contribution was greatest when the absolute amplitude of that layer's response was largest. The contribution of the inner retina was maximally significant in the interval between the prominent troughs and peaks of the intact response. The contributions of the postreceptor and photoreceptor responses were maximally significant at the prominent troughs and peaks of the intact response. CONCLUSIONS: The results of the model were in good overall agreement with previous interpretations of the cellular contributions to the mfERG. There was also fair agreement with pharmacologically dissected monkey mfERG responses. Thus, the estimations of the contributions of the retinal layers to the mfERG so produced appeared plausible.

Cerebral visual impairment in CDKL5 deficiency disorder: vision as an outcome measure.

AIM: To characterize the neuro-ophthalmological phenotype of cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) and assess visual acuity as a reproducible, quantitative outcome measure. METHOD: We retrospectively analyzed clinical data from patients with CDD. Complete neuro-ophthalmological assessments, including visual acuity, were evaluated. RESULTS: Of 26 patients (22 females, four males; median age 4y, interquartile range 2y 1mo-7y 10mo), cerebral visual impairment (CVI), defined as visual dysfunction in the absence of ocular or anterior visual pathway abnormalities, was diagnosed in all those over 2 years of age. Ophthalmological examinations revealed nystagmus in 10 patients and strabismus in 24 patients. Visual acuity was measured in 24 patients, by preferential looking in all and by sweep visual evoked potential in 13. Visual acuities were lower than age expectations and demonstrated improvement in the first 3 years. Adjusting for age and sex, average preferential looking visual acuity after 2 years of age was higher in patients with intact mobility than in those who were non-mobile. INTERPRETATION: CVI was observed in patients with CDD. Visual acuity improved over time and correlated with mobility. Visual acuity, as a quantifiable measure of visual function, should be considered as an outcome measure in pre-clinical and clinical studies for CDD. What this paper adds Cerebral visual impairment is highly prevalent in cyclin-dependent kinase-like 5 deficiency disorder (CDD). Visual acuity is a measurable quantitative outcome measure in CDD. Visual acuity in CDD correlates with gross motor ability.

Dark-adapted threshold and electroretinogram for diagnosis of Usher syndrome.

PURPOSE: To determine the utility of ophthalmology evaluation, dark-adapted threshold, and full-field electroretinogram for early detection of Usher syndrome in young patients with bilateral sensorineural hearing loss. METHODS: We identified 39 patients with secure genetic diagnoses of Usher Syndrome. Visual acuity, spherical equivalent, fundus appearance, dark-adapted threshold, and full-field electroretinogram results were summarized and compared to those in a group of healthy controls with normal hearing. In those Usher patients with repeated measures, regression analysis was done to evaluate for change in visual acuity and dark-adapted threshold with age. Spherical equivalent and full-field electroretinogram responses from dark- and light-adapted eyes were evaluated as a function of age. RESULTS: The majority of initial visual acuity and spherical equivalent results were within normal limits for age. Visual acuity and dark-adapted threshold worsened significantly with age in Usher type 1 but not in Usher type 2. At initial test, full-field electroretinogram responses from dark- and light-adapted eyes were abnormal in 53% of patients. Remarkably, nearly half of our patients (17% of Usher type 1 and 30% of Usher type 2) would have been missed by tests of retinal function alone if evaluated before age 10. CONCLUSIONS: Although there is an association of abnormal dark-adapted threshold and full-field electroretinogram at young ages in Usher patients, it appears that a small but important proportion of patients would not be detected by tests of retinal function alone. Thus, genetic testing is needed to secure a diagnosis of Usher syndrome.

Extracting the ON and OFF contributions to the full-field photopic flash electroretinogram using summed growth curves.

Under cone-mediated (photopic) conditions, an "instantaneous" flash of light, including both stimulus onset and offset, will simultaneously activate both "ON" and "OFF" bipolar cells, which either depolarize (ON) or hyperpolarize (OFF) in response and, respectively, produce positive-going and negative-going deflections in the electroretinogram (ERG). The stimulus-response (SR) relationship of the photopic ON response demonstrates logistic growth, like that manifested in the rod-mediated (scotopic) b-wave, which is driven by a single class of depolarizing bipolar cell. However, the photopic b-wave SR function is importantly shaped by OFF responses, leading to a "photopic hill." Furthermore, both on and off stimuli elicit activity in both ON and OFF bipolar cells. This has made it difficult to produce meaningful parameters for ready interpretation of the photopic b-wave SR relationship. Therefore, we evaluated whether the sum of sigmoidal SR functions, as descriptors of the depolarizing and hyperpolarizing components of the photopic flash ERG, could be used to elucidate and quantitate the mechanisms that produce the photopic hill. We used a novel fitting routine to optimize a sum of simple sigmoidal curves to SR data in five groups of subjects: Healthy adult, 10-week-old infant, congenital stationary night blindness (CSNB), X-linked juvenile retinoschisis (XJR), and preterm-born, both without and with a history of retinopathy of prematurity (ROP). Differences in ON and OFF amplitude, sensitivity, and implicit time among the groups were then compared using parameters extracted from these fits. We found that our modeling procedure enabled plausible derivations of ON and OFF pathway contributions to the ERG, and that the parameters produced appeared to have physiological relevance. In adult subjects, the ON and OFF amplitudes were similar in magnitude with respectively longer and shorter implicit times. Infant, CSNB, and XJR subjects showed significant ON pathway deficits. History of preterm-birth, without or with a diagnosis of ROP, did not much affect cone responses.

Progressive retinal degeneration in a girl with Knobloch syndrome who presented with signs of ocular albinism.

PURPOSE: We report for the first time electroretinographic (ERG) evidence of progressive retinal abnormalities in a girl who presented in infancy with ocular features of albinism and gradually developed choroidal sclerosis and patchy retinal atrophy leading to a diagnosis of Knobloch syndrome (KS, OMIM 267750, COL18A1). METHODS: At age 2 months, nystagmus and esotropia prompted ophthalmic evaluation. The appearance of choroidal sclerosis and atrophic retinal patches led to further evaluation at age 8 years. Genetics consultation was obtained in infancy and again at age 8 years as retinal findings evolved. Full field ERG responses in both scotopic and photopic conditions were recorded at both ages and compared to those in healthy control subjects. RESULTS: At age 2 months ERG response parameters were within normal limits for age and tyrosinase (TYR) gene sequencing revealed one novel mutation, p.S466F, and the temperature-sensitive polymorphism, p.R402Q, suggesting the diagnosis of oculocutaneous albinism type 1 (OCA1). At age 8 years, there was significant attenuation of both scotopic and photopic ERG responses. Genetic re-analysis led to the identification of a homozygous mutation, c.3213dupC, in the COL18A1 gene, thus confirming the diagnosis of Knobloch syndrome. CONCLUSIONS: Our patient with Knobloch syndrome developed abnormal ERG responses similar to those found in col18a1 knockout mice. Thus, we have documented progressive attenuation of the scotopic and photopic responses in KS.

Dermoscopy for Identification of Basal Cell Carcinomas in Basal Cell Nevus Syndrome During Carbon Dioxide Laser Surgery.

Basal cell nevus syndrome (BCNS) is a rare autosomal dominant condition best known for the development of early and multiple basal cell carcinomas (BCCs). Because the condition requires lifetime surveillance for new cancers, an efficient method of identification and treatment is desirable, especially in children. Dermoscopy and carbon dioxide laser have previously been shown to be effective in the identification and treatment, respectively, of BCCs in BCNS. We present here a case illustrating that the use of these modalities in a single session provides patients with safe and effective treatment that is efficient, cosmetically acceptable, and minimally disruptive to their lives.

Vigabatrin can enhance electroretinographic responses in pigmented and albino rats.

PURPOSE: To evaluate the effects of the antiepileptic medication vigabatrin (VGB) on the retina of pigmented rats. METHODS: Scotopic and photopic electroretinograms were recorded from dark- and light-adapted Long-Evans (pigmented) and Sprague Dawley (albino) rats administered, daily, 52-55 injections of 250 mg·kg(-1)·day(-1) VGB or 25-26 injections of 500 mg·kg(-1)·day(-1) VGB, or a corresponding number of sham injections. Sensitivity and saturated amplitude of the rod photoresponse (S, Rm(P3)) and postreceptor response (1/σ, Vm) were derived, as were sensitivity and amplitude of the cone-mediated postreceptor response (1/σ(cone), Vm(cone)). The oscillatory potentials and responses to a series of flickering lights (6.25, 12.5, 25 and 50 Hz) were studied in the time and frequency domains. A subset of rats' eyes was harvested for Western blotting or histology. RESULTS: Of the parameters derived from dark-adapted ERG responses, in both pigmented and albino rats, VGB repeatedly and reliably enhanced electroretinographic parameters; no significant ERG deficits were noted. No significant alterations were observed in ER/oxidative stress or in the Akt cell death/survival pathway. There were migrations of photoreceptor nuclei toward the RPE and outgrowths of bipolar cell dendrites into the outer nuclear layer in VGB-treated rats; these were never observed in sham-treated animals. CONCLUSIONS: Although VGB is associated with retinal dysfunction in patients and VGB toxicity has been demonstrated by other laboratories in the albino rat, in our pigmented and albino rats, VGB did not induce deficits in, but rather enhanced, retinal function. Nonetheless, retinal neuronal dysplasia was observed.

Early morphea mimicking acquired port-wine stain.

We report the case of a 2.5-year-old girl with linear morphea initially diagnosed as an acquired port-wine stain (PWS). She underwent three treatments to the right face using the pulsed dye laser (PDL) before sclerotic changes were observed and the correct diagnosis was confirmed with histopathology. Treatment using the PDL reduced the skin erythema but did not prevent subsequent sclerosis. The sclerosis became most prominent superior to the patient's right ear in an area not treated using the laser. A review of the English-language medical literature identified no cases of morphea triggered using a PDL, but there were several reports of early morphea misdiagnosed as an acquired PWS. Briefly, we review those cases, as well as morphea subtypes, and comment on how the pathophysiology of morphea may lend itself to an early underrecognized inflammatory presentation, delaying diagnosis.

Crusted scabies misdiagnosed as erythrodermic psoriasis in a 3-year-old girl with down syndrome.

Scabies is a highly contagious infestation with the Sarcoptes scabiei var hominis mite. The variety of clinical presentations make timely, accurate diagnosis problematic. We report the case of a 3-year-old girl with Down syndrome and crusted scabies initially misdiagnosed as erythrodermic psoriasis.

Congenital erosive and vesicular dermatosis with reticulated supple scarring: unifying clinical features.

BACKGROUND: Congenital erosive and vesicular dermatosis (CEVD) healing with reticulated supple scarring, a condition usually observed in premature neonates, presents at birth with vesicles and erosions. Lesions typically heal within a few months, leaving behind scarring with a distinctive supple and reticulated texture. OBJECTIVES: We sought to merge existing literature with new cases to further define CEVD. METHODS: We analyzed 19 previous reports of CEVD and added 9 additional patients; we identified unifying characteristics of this cohort. RESULTS: In 28 total cases, notable features included: preterm birth (79%), nail abnormalities (46%), hyperthermia/hypohidrosis (46%), a history of maternal chorioamnionitis (43%), alopecia (43%), neurodevelopmental and ophthalmologic abnormalities (36% each), tongue atrophy (29%), or a combination of these. Patients with CEVD may be prone to postnatal herpetic superinfections. Previously unreported findings included: erosive lichen planus, digital tip gangrene, and hydronephrosis. LIMITATIONS: The small patient sampling makes it difficult to define diagnostic criteria. As certain findings are associated with prematurity, it is unclear to what extent these features result from CEVD, premature birth, or another intrauterine pathology. CONCLUSIONS: Although rare, CEVD should be considered in the differential diagnosis of neonatal vesicles/erosions in the context of a negative infectious workup. This review strengthens the spectrum of CEVD features, thus facilitating its recognition by clinicians.

Next-generation sequencing analysis of gene regulation in the rat model of retinopathy of prematurity.

PURPOSE: The purpose of this study was to identify the genes, biochemical signaling pathways, and biological themes involved in the pathogenesis of retinopathy of prematurity (ROP). METHODS: Next-generation sequencing (NGS) was performed on the RNA transcriptome of rats with the Penn et al. (Pediatr Res 36:724-731, 1994) oxygen-induced retinopathy model of ROP at the height of vascular abnormality, postnatal day (P) 19, and normalized to age-matched, room-air-reared littermate controls. Eight custom-developed pathways with potential relevance to known ROP sequelae were evaluated for significant regulation in ROP: The three major Wnt signaling pathways, canonical, planar cell polarity (PCP), and Wnt/Ca(2+); two signaling pathways mediated by the Rho GTPases RhoA and Cdc42, which are, respectively, thought to intersect with canonical and non-canonical Wnt signaling; nitric oxide signaling pathways mediated by two nitric oxide synthase (NOS) enzymes, neuronal (nNOS) and endothelial (eNOS); and the retinoic acid (RA) signaling pathway. Regulation of other biological pathways and themes was detected by gene ontology using the Kyoto Encyclopedia of Genes and Genomes and the NIH's Database for Annotation, Visualization, and Integrated Discovery's GO terms databases. RESULTS: Canonical Wnt signaling was found to be regulated, but the non-canonical PCP and Wnt/Ca(2+) pathways were not. Nitric oxide signaling, as measured by the activation of nNOS and eNOS, was also regulated, as was RA signaling. Biological themes related to protein translation (ribosomes), neural signaling, inflammation and immunity, cell cycle, and cell death were (among others) highly regulated in ROP rats. CONCLUSIONS: These several genes and pathways identified by NGS might provide novel targets for intervention in ROP.

Alterations of the tunica vasculosa lentis in the rat model of retinopathy of prematurity.

PURPOSE: To study the relationship between retinal and tunica vasculosa lentis (TVL) disease in retinopathy of prematurity (ROP). Although the clinical hallmark of ROP is abnormal retinal blood vessels, the vessels of the anterior segment, including the TVL, are also altered. METHODS: ROP was induced in Long-Evans pigmented and Sprague Dawley albino rats; room-air-reared (RAR) rats served as controls. Then, fluorescein angiographic images of the TVL and retinal vessels were serially obtained with a scanning laser ophthalmoscope near the height of retinal vascular disease, ~20 days of age, and again at 30 and 64 days of age. Additionally, electroretinograms (ERGs) were obtained prior to the first imaging session. The TVL images were analyzed for percent coverage of the posterior lens. The tortuosity of the retinal arterioles was determined using Retinal Image multiScale Analysis (Gelman et al. in Invest Ophthalmol Vis Sci 46:4734-4738, 2005). RESULTS: In the youngest ROP rats, the TVL was dense, while in RAR rats, it was relatively sparse. By 30 days, the TVL in RAR rats had almost fully regressed, while in ROP rats, it was still pronounced. By the final test age, the TVL had completely regressed in both ROP and RAR rats. In parallel, the tortuous retinal arterioles in ROP rats resolved with increasing age. ERG components indicating postreceptoral dysfunction, the b-wave, and oscillatory potentials were attenuated in ROP rats. CONCLUSIONS: These findings underscore the retinal vascular abnormalities and, for the first time, show abnormal anterior segment vasculature in the rat model of ROP. There is delayed regression of the TVL in the rat model of ROP. This demonstrates that ROP is a disease of the whole eye.

The Development of Retinal Function and Refractive Error in Children With Retinopathy of Prematurity.

Purpose: The purpose of this study was to test the hypothesis that retinopathy of prematurity (ROP) prolongs development of rod-mediated thresholds for detection of stimuli at 10 degrees but not 30 degrees eccentricity. In addition, to evaluate the thresholds at each site for an association with visual acuity (VA) and spherical equivalent (SE). Methods: We estimated rod-mediated dark-adapted thresholds (DATs) for the detection of 2 degree diameter, 50 ms, blue (λ < 510 nm) flashes at 10 degrees and 30 degrees eccentric in former preterm subjects (n = 111), stratified by ROP severity: None (n = 32), Mild (n = 66), and Severe (n = 13). We also tested Term-born (n = 28) controls. To determine the age at half-maximal sensitivity (Agehalf) for each group and eccentricity, we fit DATs to logistic growth curves. We obtained VA and SE for Preterm subjects and evaluated the course of threshold development at 10 degrees and 30 degrees for significant association with VA and SE predicted at age 10 years. Results: DAT development at 10 degrees was significantly delayed in ROP (Mild and Severe); ROP did not significantly alter DAT development at 30 degrees. At age 10 years, among Preterm subjects, both VA and SE were significantly associated with group (None,Mild, and Severe). SE was predicted by the course of DAT development at 30 degrees. VA was not associated with the course of DAT development at 10 degrees. Conclusions: At 10 degrees, ROP-whether mild or severe-is associated with significant delays in DAT development, evidence that the late-maturing central retina is vulnerable to ROP. The association of 30 degree threshold and myopia are evidence that more peripheral retina is important to refractive development.

A Simplified Model of Activation and Deactivation of Human Rod Phototransduction-An Electroretinographic Study.

Purpose: To test the hypothesis that a simple model having properties consistent with activation and deactivation in the rod approximates the whole time course of the photoresponse. Methods: Routinely, an exponential of the form f = α·(1 - exp(-(τ·(t - teff)s-1))), with amplitude α, rate constant τ (often scaled by intensity), irreducible delay teff, and time exponent s-1, is fit to the early period of the flash electroretinogram. Notably, s (an integer) represents the three integrating stages in the rod amplification cascade (rhodopsin isomerization, transducin activation, and cGMP hydrolysis). The time course of the photoresponse to a 0.17 cd·s·m-2 conditioning flash (CF) was determined in 21 healthy eyes by presenting the CF plus a bright probe flash (PF) in tandem, separated by interstimulus intervals (ISIs) of 0.01 to 1.4 seconds, and calculating the proportion of the PF a-wave suppressed by the CF at each ISI. To test if similar kinetics describe deactivation, difference of exponential (DoE) functions with common α and teff parameters, respective rate constants for the initiation (I) and quenching (Q) phases of the response, and specified values of s (sI, sQ), were compared to the photoresponse time course. Results: As hypothesized, the optimal values of sI and sQ were 3 and 2, respectively. Mean ± SD α was 0.80 ± 0.066, I was 7700 ± 2400 m2·cd-1·s-3, and Q was 1.4 ± 0.47 s-1. Overall, r2 was 0.93. Conclusions: A method, including a DoE model with just three free parameters (α, I, Q), that robustly captures the magnitude and time-constants of the complete rod response, was produced. Only two steps integrate to quench the rod photoresponse.

Electroretinographic Responses in Retinopathy of Prematurity Treated Using Intravitreal Bevacizumab or Laser.

PURPOSE: Intravitreal injection of bevacizumab (IVB) offers advantages over laser photoablation for treatment of type 1 retinopathy of prematurity (ROP). However, retinal function has not, to date, been quantitatively compared following these interventions. Therefore, electroretinography (ERG) was used compare retinal function among eyes treated using IVB or laser, and control eyes. In addition, among the IVB-treated eyes, ERG was used to compare function in individuals in whom subsequent laser was and was not required. DESIGN: Prospective clinical cohort study. METHODS: ERG was used to record dark- and light-adapted stimulus/response functions in 21 children treated using IVB (12 of whom required subsequent laser in at least 1 eye for persistent avascular retina [PAR]). Sensitivity and amplitude parameters were derived from the a-wave, b-wave, and oscillatory potentials (OPs), representing activity in photoreceptor, postreceptor, and inner retinal cells, respectively. These parameters were then referenced to those of 76 healthy, term-born controls and compared to those of 10 children treated using laser only. RESULTS: In children with treated ROP, every ERG parameter was significantly below the mean in controls. However, these significant ERG deficits did not differ between IVB- and laser-treated eyes. Among children treated using IVB, no ERG parameter was significantly associated with dose or need for subsequent laser. CONCLUSION: Retinal function was significantly impaired in treated ROP eyes. Function in IVB-treated eyes did not differ from that in laser-treated eyes. Functional differences also did not distinguish those IVB-treated eyes that would subsequently need laser for PAR.

Electroretinographic (ERG) responses in pediatric patients using vigabatrin.

The antiepileptic drug vigabatrin is known to cause retinal and visual dysfunction, particularly visual field defects, in some patients. Electroretinography (ERG) is used in an attempt to identify adverse effects of vigabatrin (VGB) in patients who are not candidates for conventional perimetry. We report data from 114 pediatric patients taking VGB referred for clinical evaluation; median age at test was 22.9 (2.4 to 266.1) months, and median duration of VGB use was 9.7 (0.3 to 140.7) months. Twenty-seven of them were tested longitudinally (3 to 12 ERG tests). ERG responses to full-field stimuli were recorded in scotopic and photopic conditions, and results were compared to responses from healthy control subjects. We found that abnormalities of photoreceptor and post-receptor ERG responses are frequent in these young patients. The most frequently abnormal scotopic parameter was post-receptor sensitivity, log σ, derived from the b-wave stimulus-response function; the most frequently abnormal photopic parameter was the implicit time of the OFF response (d-wave) to a long (150 ms) flash. Abnormal 30-Hz flicker response amplitude, previously reported to be a predictor of visual field loss, occurred infrequently. For the group as a whole, none of the ERG parameters changed significantly with increasing duration of VGB use. Four of the 27 patients tested longitudinally showed systematic worsening of log σ with duration of VGB use. In a subset of patients who underwent perimetry (N = 39), there was no significant association of any ERG parameter with visual field defects. We cannot determine whether the ERG abnormalities we found were due solely to the effects of VGB. We caution against over-reliance on the ERG to monitor pediatric patients for VGB toxicity and recommend further development of a reliable test of peripheral vision to supplant ERG testing.

Long-term effects of retinopathy of prematurity (ROP) on rod and rod-driven function.

The purpose of this study was to determine whether recovery of scotopic sensitivity occurs in human ROP, as it does in the rat models of ROP. Following a cross-sectional design, scotopic electroretinographic (ERG) responses to full-field stimuli were recorded from 85 subjects with a history of preterm birth. In 39 of these subjects, dark adapted visual threshold was also measured. Subjects were tested post-term as infants (median age 2.5 months) or at older ages (median age 10.5 years) and stratified by severity of ROP: severe, mild, or none. Rod photoreceptor sensitivity, S (ROD), was derived from the a-wave, and post-receptor sensitivity, log σ, was calculated from the b-wave stimulus-response function. Dark adapted visual threshold was measured using a forced-choice preferential procedure. For S (ROD), the deficit from normal for age varied significantly with ROP severity but not with age group. For log σ, in mild ROP, the deficit was smaller in older subjects than in infants, while in severe ROP, the deficit was quite large in both age groups. In subjects who never had ROP, S (ROD) and log σ in both age groups were similar to those in term born controls. Deficits in dark adapted threshold and log σ were correlated in mild but not in severe ROP. The data are evidence that sensitivity of the post-receptor retina improves in those with a history of mild ROP. We speculate that beneficial reorganization of the post-receptor neural circuitry occurs in mild but not in severe ROP.

Visual cycle modulation in neurovascular retinopathy.

Rats with oxygen-induced retinopathy (OIR) model the pediatric retinal disease retinopathy of prematurity (ROP). Recent findings in OIR rats imply a causal role for the rods in the ROP disease process, although only experimental manipulation of rod function can establish this role conclusively. Accordingly, a visual cycle modulator (VCM) - with no known direct effect on retinal vasculature - was administered to "50/10 model" OIR Sprague-Dawley rats to test the hypotheses that it would 1) alter rod function and 2) consequently alter vascular outcome. Four litters of pups (N=46) were studied. For two weeks, beginning on postnatal day (P) 7, the first and fourth litters were administered 6 mg kg(-1) N-retinylacetamide (the VCM) intraperitoneally; the second and third litters received vehicle (DMSO) alone. Following a longitudinal design, retinal function was assessed by electroretinography (ERG) and the status of the retinal vessels was monitored using computerized fundus photograph analysis. Rod photoreceptor and post-receptor response amplitudes were significantly higher in VCM-treated than in vehicle-treated rats; deactivation of phototransduction was also significantly more rapid. Notably, the arterioles of VCM-treated rats showed significantly greater recovery from OIR. Presuming that the VCM did not directly affect the retinal vessels, a causal role for the neural retina - particularly the rod photoreceptors - in OIR was confirmed. There was no evidence of negative alteration of photoreceptor function consequent to VCM treatment. This finding implicates the rods as a possible therapeutic target in neurovascular diseases such as ROP.