Night Vision and Carotenoids (NVC): A Randomized Placebo Controlled Clinical Trial on Effects of Carotenoid Supplementation on Night Vision in Older Adults.

Twilight and low luminance levels are visually challenging environments for the elderly, especially when driving at night. Carotenoid rich diets are known to increase macular pigment optical density (MPOD), which in turn leads to an improvement in visual function. It is not known whether augmenting MPOD can lead to a decrease in vision related night driving difficulties. Additionally, it is unknown if carotenoid supplementation provides additional measurable benefits to one's useful field of view (UFOV) along with a decreased composite crash risk score. The aim of the study was to evaluate changes in night vision function and UFOV in individuals that took carotenoid vitamin supplements for a six-month period compared to a placebo group. METHODS: A prospective, randomized, double-blind, six-month trial of a 14 mg zeaxanthin/7 mg lutein-based supplement was carried out. Participants were randomized into active or placebo group (approx 2:1). RESULTS: n = 33 participants (26 males/7 females) participated with 93% capsule intake compliance in the supplemented group (n = 24) and placebo group (n = 9). MPOD (mean/standard error SE) in the active group increased in the Right eye from 0.35 density units (du)/0.04 SE to 0.41 du/0.05 SE; p < 0.001 and in the Left eye from 0.35 du/0.05 SE to 0.37 du, p > 0.05). The supplemented group showed significant improvements in contrast sensitivity with glare in both eyes with improvements in LogMAR scores of 0.147 and 0.149, respectively (p = 0.02 and 0.01, respectively), monocularly tested glare recovery time improved 2.76 and 2.54 s, respectively, (p = 0.008 and p = 0.02), and we also noted a decreased preferred luminance required to complete visual tasks (p = 0.02 and 0.03). Improvements in UFOV scores of divided attention (p < 0.001) and improved composite crash risk score (p = 0.004) were seen in the supplemented group. The placebo group remained unchanged. CONCLUSIONS: The NVC demonstrates that augmenting MPOD in individuals with difficulty in night vision showed measurable benefits in numerous visual functions that are important for night vision driving in this small sample RCT. Additionally, we observed an improvement in UFOV divided attention test scores and decreased composite risk scores.

Effects of Prenatal Alcohol Exposure on the Visual System of Monkeys Measured at Different Stages of Development.

Purpose: Fetal alcohol spectrum disorder (FASD) is a developmental disease characterized by behavioral problems and physical defects including malformations of the eye and associated optical defects. How these malformations affect retinal functioning is not well known, although animal models have suggested that scotopic vision is particularly deficient. Age is also known to affect scotopic vision. Here, we determined the combined effects of age and fetal alcohol exposure (FAE) on retinal function using full-field electroretinograms (ERGs) in monkeys (Chlorocebus sabaeus). Methods: ERGs were recorded in monkeys aged 3- to 12-years old, at multiple flash intensities under scotopic and photopic conditions, and functions were fit to the amplitudes of the a- and b-waves. Results: We found that both age and alcohol exposure affected ERGs. In photopic ERGs, amplitudes increased with age, and were higher in FAEs than controls, for data related to the OFF- and ON-pathways. In scotopic ERGs, amplitudes were decreased in young FAE compared with age-matched controls but only for the rod-dominated responses, while at brighter flashes, alcohol exposure led to an increase in the amplitude of the a- and b-waves. Conclusions: The ERGs from the FAE animals closely resembled the data from the older sucrose-control monkeys. This suggests that the FAE monkey retina ages more quickly than the control monkeys. This large sample of nonhuman primates, with carefully monitored ethanol exposure, demonstrates the critical interplay between age and alcohol when assessing the integrity of the retina. We suggest that ERGs might be an important adjunct to diagnosing human FASD.

Apelin protects against NMDA-induced retinal neuronal death via an APJ receptor by activating Akt and ERK1/2, and suppressing TNF-α expression in mice.

Glutamate excitotoxicity mediated by N-methyl-d-aspartate (NMDA) receptors is an important cause of retinal ganglion cell death in glaucoma. To elucidate whether apelin protects against retinal neuronal cell death, we examined protective effects of exogenous and endogenous apelin on neuronal cell death induced by intravitreal injection of NMDA in the retinas of mice. An intravitreal injection of NMDA induced neuronal cell death in both the retinal ganglion cell layer and inner nuclear layer, and reduced the amplitudes of scotopic threshold response (STR) in electroretinography studies. Both cell death and STR amplitudes decrease induced by NMDA were prevented by a co-injection of [Pyr1]-apelin-13, and were facilitated by apelin deficiency. The neuroprotective effects of [Pyr1]-apelin-13 were blocked by an apelin receptor APJ antagonist, and by inhibitors of Akt and extracellular signal-regulated kinase 1/2 signaling pathways. Additionally, an intravitreal injection of tumor necrosis factor-α (TNF-α) neutralizing antibody prevented NMDA-induced retinal neuronal cell death, and exogenous and endogenous apelin suppressed NMDA-induced upregulation of TNF-α in the retina. These results suggest that apelin protects neuronal cells against NMDA-induced death via an APJ receptor in the retina, and that apelin may have beneficial effects in the treatment of glaucoma.

Predicting vision gains with anti-VEGF therapy in neovascular age-related macular degeneration patients by using low-luminance vision.

BACKGROUND/AIMS: To evaluate baseline low-luminance visual acuity (LLVA) as a predictor of visual acuity improvement in patients with neovascular (wet) age-related macular degeneration (wAMD) receiving antivascular endothelial growth factor A (anti-VEGF) therapy. METHODS: In the HARBOR trial, 1084 treatment-naïve patients ≥50 years of age with subfoveal wAMD received intravitreal ranibizumab 0.5 or 2.0 mg monthly or as needed. To measure LLVA, patients read a normally illuminated ETDRS (Early Treatment Diabetic Retinopathy Study) chart with a neutral density filter placed in front of the study eye. Patients were assigned into quartiles based on the magnitude of the difference between best-corrected visual acuity under optimal luminance (BCVA) and LLVA (BCVA-LLVA gap). The association between mean change in BCVA from baseline and BCVA-LLVA gap at baseline was analysed using a general linear model. RESULTS: A smaller baseline BCVA-LLVA gap predicted significantly higher BCVA gains over 24 months (p<0.0001 at each month; Pearson correlation), even after controlling for baseline BCVA or stratifying by treatment arm. Patients in the smallest baseline BCVA-LLVA gap quartile gained an average of +13.4 letters compared with +2.4 letters for patients in the widest baseline BCVA-LLVA gap quartile. At months 12 and 24, the smallest baseline BCVA-LLVA gap quartile had the highest proportion of ≥15-≥30-letter gain, and the widest baseline BCVA-LLVA gap quartile had the highest proportion of ≥15-/≥30-letter loss (p<0.0001; Fisher's exact test). CONCLUSIONS: The baseline BCVA-LLVA gap is a significant predictor of visual acuity response to anti-VEGF treatment in patients with wAMD. TRIAL REGISTRATION NUMBER: NCT00891735; Post-results.

FTY720 protects retinal ganglion cells in experimental glaucoma.

PURPOSE: To investigate the neuroprotective effects of sphingosine-1-phosphate (S1P) analogue fingolimod (FTY720) in experimental glaucoma in rats. METHODS: A unilateral chronic ocular hypertensive model was established by injections of microbeads into the anterior eye chamber of adult Sprague-Dawley rats. Fingolimod was administered to one group of rats intraperitoneally every week for 3 months. The scotopic threshold response (STR) was recorded to assess the function of the inner retina. Changes in cell density in the ganglion cell layer (GCL) were evaluated by hematoxylin and eosin staining on retinal sections and axonal count of the optic nerve was performed using Bielschowsky's silver staining. Effects of drug treatment on activation of Akt and Erk1/2 were evaluated using Western blotting by assessing phosphorylation levels of these proteins. The expression of S1P receptors in the optic nerve head region was also evaluated using Western blotting and immunohistochemistry. RESULTS: Administration of FTY720 reduced the loss of STR amplitude in glaucomatous eyes (P < 0.05). Counting and plotting the cell numbers/axonal density showed significant neural preservation in the GCL and the optic nerve (P < 0.05). An increased phosphorylation level of Akt and Erk1/2 following FTY720 administration was observed. Both S1P1 and S1P5 receptors were found to be expressed in the retina and the expression of S1P1R was upregulated in experimentally-induced glaucoma. CONCLUSIONS: This study demonstrates, for the first time, that FTY720 could act as a neuroprotective agent to protect retinal ganglion cells in experimental glaucoma. Administration of this drug significantly reduces the structural and functional loss of the inner retina elicited indicating that it may potentially be used to attenuate neuronal loss and optic nerve damage in glaucomatous patients.

Cyanidin-3-glucoside extracted from mulberry fruit can reduce N-methyl-N-nitrosourea-induced retinal degeneration in rats.

PURPOSE: To investigate the effect of cyanidin-3-O-glucoside (C3G) on a rat retinal degeneration (RD) model. MATERIALS AND METHODS: Experimental RD was induced in rats by the intraperitoneal injection of N-methyl-N-nitrosourea (MNU) at 50 mg/kg. C3G extracted from mulberry (Morus alba L.) fruit (50 mg/kg) was orally administered, daily for 1, 2 and 4 weeks after MNU injection. The effects of C3G administration on MNU-induced RD retinas were histologically and functionally assessed by hematoxylin and eosin staining and electroretinography (ERG), respectively. The degree of retinal injury in C3G-administered RD rats was evaluated by immunohistochemistry with an antibody against glial fibrillary acidic protein (GFAP). The preferential protective effect of C3G on scotopic vision was examined by western blot analysis. RESULTS: Marked loss of photoreceptors in the outer nuclear layer (ONL) was observed in RD rats at 2 and 4 weeks after MNU injection, while the ONL in the MNU-induced RD rats given C3G was relatively well preserved. Immunohistochemistry with anti-GFAP showed that retinal injury was also reduced in the retinas of the rats given C3G. Functional assessment by using ERG recordings showed that scotopic ERG responses were significantly increased in RD rats given C3G for 4 weeks (p < 0.01) compared with that of untreated RD rats. In the RD rats given short-term C3G (for 1 and 2 weeks), the increase in ERG responses was not significant. In addition, western blot analysis showed that rhodopsin level in the C3G-administered RD retinas significantly increased compared to that in the non-administered RD retinas (p < 0.05), whereas red/green opsin level did not show any significant difference. CONCLUSIONS: Long-term administration of C3G extracted from mulberry fruit could structurally reduce photoreceptor damage and functionally improve scotopic visual functions in the RD rat model induced by MNU.

Negative impact of melatonin ingestion on the photopic electroretinogram of dogs.

Melatonin follows a circadian rhythm entrained by the light/dark cycle and plays a role in promoting light sensitivity at night. It has been suggested that melatonin and dopamine reciprocal inhibition may contribute to the switch between day and night vision. The purpose of this study was to investigate the impact of a high dose of melatonin administration on the photopic and scotopic electroretinogram (ERG) of dogs in the daytime, when it is not thought to be present. Photopic and scotopic ERG luminance response functions were obtained from 7 anaesthetized beagle dogs (3 males and 4 females), once without melatonin (control) and once after oral administration of melatonin (90 mg/dog). Vmax (maximal b-wave amplitude achieved) and logK (retinal sensitivity) were calculated from the derived luminance response function. Photopic flicker ERG was also recorded. In photopic condition, a-wave amplitude (control: -126.90 µV; with melatonin: -49.64 µV; p<0.001) and Vmax (control: 252.50 µV; with melatonin: 115.40 µV; p<0.001) were decreased. A significant reduction of the photopic flicker ERG amplitude was observed after melatonin ingestion. In scotopic condition, an overall difference was reported before and after melatonin ingestion for the a- and b-wave amplitude, but no change was significant for Vmax. Melatonin ingestion at a high dose during the day decreases the photopic amplitude of a- and b-wave, but has no impact on implicit time. This negative impact of melatonin on photopic system may serve to promote night vision.

Differential proteomics and functional research following gene therapy in a mouse model of Leber congenital amaurosis.

Leber congenital amaurosis (LCA) is one of the most severe forms of inherited retinal degeneration and can be caused by mutations in at least 15 different genes. To clarify the proteomic differences in LCA eyes, a cohort of retinal degeneration 12 (rd12) mice, an LCA2 model caused by a mutation in the RPE65 gene, were injected subretinally with an AAV vector (scAAV5-smCBA-hRPE65) in one eye, while the contralateral eye served as a control. Proteomics were compared between untreated rd12 and normal control retinas on P14 and P21, and among treated and untreated rd12 retinas and control retinas on P42. Gene therapy in rd12 mice restored retinal function in treated eyes, which was demonstrated by electroretinography (ERG). Proteomic analysis successfully identified 39 proteins expressed differently among the 3 groups. The expression of 3 proteins involved in regulation of apoptosis and neuroptotection (alpha A crystallin, heat shock protein 70 and peroxiredoxin 6) were investigated further. Immunofluorescence, Western blot and real-time PCR confirmed the quantitative changes in their expression. Furthermore, cell culture studies suggested that peroxiredoxin 6 could act in an antioxidant role in rd12 mice. Our findings support the feasibility of gene therapy in LCA2 patients and support a role for alpha A crystallin, heat shock protein 70 and peroxiredoxin 6 in the pathogenetic mechanisms involved in LCA2 disease process.

Necrostatin-1 protects photoreceptors from cell death and improves functional outcome after experimental retinal detachment.

Necroptosis is a recently discovered programmed necrosis. Evidence demonstrated the importance of necroptosis in neuronal cell death. Necrostatin-1 is a specific inhibitor of necroptosis. In this study, we investigated the role of necrostatin-1 on photoreceptor survival and functional protection after experimental retinal detachment (RD) in rats. Necrostatin-1/inactive analogue of necrostatin-1 was introduced into the subretinal space at RD induction and 6 hours afterward, respectively. We found that necrostatin-1 attenuated retinal histopathological damage and reduced plasma membrane breakdown (a morphological hallmark of necroptosis) in outer retinal layers. Transmission electron microscopy showed that necrostatin-1 directly protected neurons by inhibiting necroptotic, not apoptotic, cell death. Treatment with necrostatin-1 inhibited the induction of receptor-interacting protein kinase phosphorylation after RD (a biomarker of necroptosis). Finally, electroretinographic recording proved that necrostatin-1 contributed to objective functional improvement after RD. These findings indicate that necrostatin-1 is a promising therapeutic agent that protects photoreceptors from necroptosis and improves functional outcome.

Effects of common anesthetics on eye movement and electroretinogram.

High-resolution magnetic resonance imaging (MRI) provides non-invasive images of retinal anatomy, physiology, and function with depth-resolved laminar resolution. Eye movement and drift, however, could limit high spatial resolution imaging, and anesthetics that minimize eye movement could significantly attenuate retinal function. The aim of this study was to determine the optimal anesthetic preparations to minimize eye movement and maximize visual-evoked retinal response in rats. Eye movements were examined by imaging of the cornea with a charge-coupled device (CCD) camera under isoflurane, urethane, ketamine/xylazine, and propofol anesthesia at typical dosages in rats. Combination of the paralytic pancuronium bromide with isoflurane or ketamine/xylazine anesthesia was also examined for the eye movement studies. Visual-evoked retinal responses were evaluated using full-field electroretinography (ERG) under isoflurane, ketamine/xylazine, urethane, and ketamine/xylazine + pancuronium anesthesia in rats. The degree of eye movement, measured as displacement per unit time, was the smallest under 1% isoflurane + pancuronium anesthesia. The ketamine/xylazine groups showed larger dark-adapted ERG a- and b-waves than other anesthetics tested. The isoflurane group showed the shortest b-wave implicit times. Photopic ERGs in the ketamine/xylazine groups showed the largest b-waves with the isoflurane group showing slightly shorter implicit times at the higher flash intensities. Oscillatory potentials revealed an early peak in the isoflurane group compared with ketamine/xylazine and urethane groups. Pancuronium did not affect the a- and b-wave, but did increase oscillatory potential amplitudes. Compared with the other anesthetics tested here, ketamine/xylazine + pancuronium was the best combination to minimize eye movement and maximize retinal function. These findings should set the stage for further development and application of high-resolution functional imaging techniques, such as MRI, to study retinal anatomy, physiology, and function in anesthetized rats.

Post-receptoral contributions to the rat scotopic electroretinogram a-wave.

The electroretinogram is a widely used objective measure of visual function. The best characterised feature of the full-field dark-adapted flash ERG, is the earliest corneal negativity, the a-wave, which primarily reflects photoreceptoral responses. However, recent studies in humans and primates show that there are post-receptoral contributions to the a-wave. It is not clear if such contributions exist in the rat a-wave. We consider this issue in the rat a-wave, using intravitreal application of pharmacological agents that isolate post-receptoral ON-pathways and OFF-pathways. In anaesthetised adult long Evans rats, we show that the ON-pathway (2-amino-4-phosphonobutyric acid, APB sensitive) makes negligible contribution to the a-wave. In contrast, CNQX (6-cyano-7-nitroquinoxaline-2,3-dione) or PDA (cis-piperidine-2,3-dicarboxylic acid) sensitive mechanisms modify the a-wave in two ways. First, for bright luminous energies, OFF-pathway inhibition (CNQX or PDA) results in a 22% reduction to the early phase of the leading edge of the a-wave up to 14 ms. Second, OFF-pathway inhibition removed a corneal negativity that resides between the a-wave trough and the b-wave onset.

gp130 activation in Müller cells is not essential for photoreceptor protection from light damage.

Members of IL-6 family cytokines, such as leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF), activate the common signal-transducing receptor gp130. We and others have previously shown that application of exogenous gp130 ligands promotes photoreceptor survival in light-induced and inherited retinal degeneration in animal models. While there is strong evidence that gp130 plays an essential role in photoreceptor protection, it is not clear whether protection is cell-autonomous in photoreceptors or an effect of Müller cell activation. To investigate the role of Müller cells in gp130-mediated photoreceptor protection, we have generated conditional gp130 knockout (KO) mice in retinal Müller cells using the Cre/lox system. Western blot and immunohistochemical analyses show that in our conditional gp130 KO mice, approximately 50% Müller cells no longer respond to LIF with activation of known downstream signaling proteins, STAT3 and ERK1/2. Despite the loss of gp130 activity in many Müller cells, intravitreal injection of LIF still induced significant degree of photoreceptor protection that was comparable to normal littermates. These data suggest that Müller cell activation of gp130 is not essential for photoreceptor protection, and support the hypothesis that the protection is mediated by cell-autonomous mechanisms in photoreceptors.

A randomized, double-blind, safety and tolerability study to assess the ophthalmic and renal effects of tafenoquine 200 mg weekly versus placebo for 6 months in healthy volunteers.

A randomized, double-blind, placebo-controlled study was conducted to assess the effect of tafenoquine, 200 mg weekly for 6 months on ophthalmic and renal safety. This trial was carried out after observations in previous clinical trials that tafenoquine may be associated with the development of corneal deposits and elevations in serum creatinine. In 120 healthy volunteers who received tafenoquine or placebo in a 2:1 randomization, there was no effect on night vision or other ophthalmic indices measured. Persons taking tafenoquine also showed no difference in mean change in glomerular filtration rate (GFR, mL/s/1.73 m(2)) after 6 months of dosing, with a treatment difference of -0.061 (95% confidence interval, -0.168, 0.045), and non-inferiority margin of -0.247 mL/s/1.73 m(2). Tafenoquine was well tolerated over the course of the study. The results of this study showed no clinically significant effects of tafenoquine on ophthalmic or renal function, and support its continued development as an antimalarial drug.

Intravitreal administration of the anti-TNF monoclonal antibody infliximab in the rabbit.

BACKGROUND: Tumor necrosis factor (TNF) is known to play an important role in various immune-mediated ocular diseases; intravenous administration of the anti-TNF monoclonal antibody infliximab has proved beneficial in such cases. Since intravitreal injection (when available) is a substitute for systemic administration of various drugs targeting the eye, we aimed to evaluate the safety of intravitreal injection of infliximab in the rabbit eye. METHODS: Seven groups of New Zealand white rabbits (four animals in each group) received a single unilateral intravitreal injection (0.1 ml) of increasing doses of infliximab (namely 1, 2, 5, 8, 10 or 20 mg infliximab [Remicade]) or a sham injection respectively. Slit-lamp biomicroscopy, fundoscopy and electrophysiology recordings, i.e. scotopic, photopic and flicker responses, were performed at baseline and after 1, 5, 10, 15, 30 and 45 days. Infliximab-injected eyes were compared with sham-injected and with uninjected fellow eyes (n = 28). Animals were euthanized on day 45 for histopathological examination of the retinas. RESULTS: Clinical examination and electrophysiological testing were consistently unremarkable after either sham or 1 mg or 2 mg infliximab injections. In contrast, electrophysiological recordings were significantly reduced in a dose-dependent manner from day 1 through day 45, after 5, 8, 10 and 20 mg infliximab injections. Flicker responses were the most sensitive in detecting the lower toxic dose of 5 mg. Histopathological findings were similar in uninjected and sham-injected eyes, as well as after 1 mg or 2 mg infliximab injections. Consistent with the functional abnormalities, retinal deformities and diffuse edema were observed after injection of 5 mg or higher doses of infliximab. CONCLUSIONS: Intravitreal infliximab may be safely administered up to a dose of 2 mg in the rabbit eye. Such doses can be used in the design of future clinical trials assessing the effects of infliximab for selected patients with immune-mediated ocular conditions.