Evaluation of a low-resource screening strategy for ophthalmic pathologies and associated neurological morbidity in an older Tanzanian HIV-positive population.

Globally, 43 million people are living with HIV, 90% in developing countries. Increasing life expectancy with combination antiretroviral therapy (cART) results in chronic complications, including HIV-associated neurocognitive disorders (HAND) and eye diseases. HAND screening is currently challenging. Our aim was to evaluate clinical utility of retinopathy as a screening measure of HAND in older cART-treated individuals in Tanzania and feasibility of smartphone-based retinal screening in this low-resource setting. A cross-sectional systematic sample aged ≥ 50-years attending routine HIV follow-up in Tanzania were comprehensively assessed for HAND by American Academy of Neurology criteria and received ophthalmic assessment including smartphone-based retinal imaging. HAND and ophthalmic assessments were independent and blinded. Diagnostic accuracy was evaluated by AUROC curves. Of 129 individuals assessed, 69.8% were visually impaired. Thirteen had retinopathy. HAND prevalence was 66.7%. Retinopathy was significantly associated with HAND but HIV-disease factors (CD4, viral load) were not. Diagnostic accuracy of retinopathy for HAND was poor (AUROC 0.545-0.617) but specificity and positive predictive value were high. We conclude that ocular pathology and HAND appear highly prevalent in this low-resource setting. Although retinal screening cannot be used alone identify HAND, prioritization of individuals with abnormal retinal screening is a potential strategy in low-resource settings.

Assessment of macular choroidal thickness, central macular thickness and retinal nerve fiber layer in patients receiving oral isotretinoin treatment.

PURPOSE: To investigate the impact of oral isotretinoin therapy in choroidal thickness, central macular thickness (CMT), and retinal nerve fibre layer (RNFL) thickness using optical coherence tomography (OCT). PATIENTS AND METHODS: Choroidal thicknesses, CMT, and RNFL thickness of 64 eyes were evaluated at baseline and the end of the third month of isotretinoin therapy by spectral-domain OCT. For assessment of choroidal thickness, OCT measurements were obtained at the fovea with 6 additional measurements at adjacent locations (at 500-1000-1500 µm temporal to the fovea and 500-1000-1500 µm nasal to the fovea). RESULTS: There was not a statistically significant difference between the baseline and third-month follow-up measurements of choroidal thicknesses at seven distinct locations (p > 0.05). Similarly, RNFL thickness and CMT did not change with a mean dose of 30 (±6) mg per day isotretinoin therapy during follow-up (101.82 vs 102.24, p = 0.079; 217.77 vs 217.25, p = 0.731, respectively). CONCLUSION: After the use of oral isotretinoin for 3 months, no significant side effects have been observed in choroidal thickness, CMT, and RNFL thickness by OCT.

Treatment regimens for administration of anti-vascular endothelial growth factor agents for neovascular age-related macular degeneration.

BACKGROUND: Age-related macular degeneration (AMD) is one of the leading causes of permanent blindness worldwide. The current mainstay of treatment for neovascular AMD (nAMD) is intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) agents: aflibercept, ranibizumab, and off-label bevacizumab. Injections can be given monthly, every two or three months ('extended-fixed'), or as needed (pro re nata (PRN)). A variant of PRN is 'treat-and-extend' whereby injections are resumed if recurrence is detected and then delivered with increasing intervals. Currently, injection frequency varies among practitioners, which underscores the need to characterize an optimized approach to nAMD management. OBJECTIVES: To investigate the effects of monthly versus non-monthly intravitreous injection of an anti-VEGF agent in people with newly diagnosed nAMD. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, LILACS, and three trials registers from 2004 to October 2019; checked references; handsearched conference abstracts; and contacted pharmaceutical companies to identify additional studies. SELECTION CRITERIA: We included randomized controlled trials (RCTs) that compared different treatment regimens for anti-VEGF agents in people with newly diagnosed nAMD. We considered standard doses only (ranibizumab 0.5 mg, bevacizumab 1.25 mg, aflibercept 2.0 mg, or a combination of these). DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods for trial selection, data extraction, and analysis. MAIN RESULTS: We included 15 RCTs. The total number of participants was 7732, ranging from 37 to 2457 in each trial. The trials were conducted worldwide. Of these, six trials exclusively took place in the US, and three included centers from more than one country. Eight trials were at high risk of bias for at least one domain and all trials had at least one domain at unclear risk of bias. Seven trials (3525 participants) compared a PRN regimen with a monthly injection regimen, of which five trials delivered four to eight injections using standard PRN and three delivered nine or 10 injections using a treat-and-extend regimen in the first year. The overall mean change in best-corrected visual acuity (BCVA) at one year was +8.8 letters in the monthly injection group. Compared to the monthly injection, there was moderate-certainty evidence that the mean difference (MD) in BCVA change at one year for the standard PRN subgroup was -1.7 letters (95% confidence interval (CI) -2.8 to -0.6; 4 trials, 2299 participants), favoring monthly injections. There was low-certainty evidence of a similar BCVA change with the treat-and-extend subgroup (0.5 letters, 95% CI -3.1 to 4.2; 3 trials, 1226 participants). Compared to monthly injection, there was low-certainty evidence that fewer participants gained 15 or more lines of vision with standard PRN treatment at one year (risk ratio (RR) 0.87, 95% CI 0.76 to 0.99; 4 trials, 2299 participants) and low-certainty evidence of a similar gain with treat-and-extend versus monthly regimens (RR 1.11, 95% CI 0.91 to 1.36; 3 trials, 1169 participants). The mean change in central retinal thickness was a decrease of -166 µm in the monthly injection group; the MD compared with standard PRN was 21 µm (95% CI 6 to 32; 4 trials, 2215 participants; moderate-certainty evidence) and with treat-and extend was 22 µm (95% CI 37 to -81 µm; 2 trials, 635 participants; low-certainty evidence), in favor of monthly injection. Only one trial (498 participants) measured quality of life and reported no evidence of a difference between regimens, but data could not be extracted (low-certainty evidence). Both PRN regimens (standard and 'treat-and-extend') used fewer injections than monthly regimens (standard PRN: MD -4.6 injections, 95% CI -5.4 to -3.8; 4 trials, 2336 participants; treat-and-extend: -2.4 injections, 95% CI -2.7 to -2.1 injections; moderate-certainty evidence for both comparisons). Two trials provided cost data (1105 participants, trials conducted in the US and the UK). They found that cost differences between regimens were reduced if bevacizumab rather than aflibercept or ranibizumab were used, since bevacizumab was less costly (low-certainty evidence). PRN regimens were associated with a reduced risk of endophthalmitis compared with monthly injections (Peto odds ratio (OR) 0.13, 95% CI 0.04 to 0.46; 6 RCTs, 3175 participants; moderate-certainty evidence). Using data from all trials included in this review, we estimated the risk of endophthalmitis with monthly injections to be 8 in every 1000 people per year. The corresponding risk for people receiving PRN regimens was 1 in every 1000 people per year (95% CI 0 to 4). Three trials (1439 participants) compared an extended-fixed regimen (number of injections reported in only one large trial: 7.5 in one year) with monthly injections. There was moderate-certainty evidence that BCVA at one year was similar for extended-fixed and monthly injections (MD in BCVA change compared to extended-fixed group: -1.3 letters, 95% CI -3.9 to 1.3; RR of gaining 15 letters or more: 0.94, 95% CI 0.80 to 1.10). The change in central retinal thickness was a decrease of 137 µm in the monthly group; the MD with the extended-fixed group was 8 µm (95% CI -11 to 27; low-certainty evidence). The frequency of endophthalmitis was lower in the extended-fixed regimen compared to the monthly group, but this estimate was imprecise (RR 0.19, 95% CI 0.03 to 1.11; low-certainty evidence). If we assumed a risk of 8 cases of endophthalmitis in 1000 people receiving monthly injections over one year, then the corresponding risk with extended-fixed regimen was 2 in 1000 people (95% CI 0 to 9). Other evidence comparing different extended-fixed or PRN regimens yielded inconclusive results. AUTHORS' CONCLUSIONS: We found that, at one year, monthly regimens are probably more effective than PRN regimens using seven or eight injections in the first year, but the difference is small and clinically insignificant. Endophthalmitis is probably more common with monthly injections and differences in costs between regimens are higher if aflibercept or ranibizumab are used compared to bevacizumab. This evidence only applies to settings in which regimens are implemented as described in the trials, whereas undertreatment is likely to be common in real-world settings. There are no data from RCTs on long-term effects of different treatment regimens.

Physiological assessment of high glucose neurotoxicity in mouse and rat retinal explants.

One of the tissues of the central nervous system most affected by diabetes is the retina. Despite a growing understanding of the biochemical processes involved in glucose toxicity, little is known about the physiological consequences of chronic high glucose (HG) on individual neurons and neuronal circuits. Electroretinogram recordings suggest that retinal bipolar cells (BCs), which filter and transmit photoreceptor output to the inner retina, are among the first cells affected by diabetic conditions, and may therefore serve as sensitive early biomarkers for incipient neuronal damage caused in diabetes. Here, we comparatively assessed retinal integrity, calcium responses, and the electrophysiological profiles of specific BC types of mouse and rat organotypic retinal explants after 1 to 3 weeks in tissue culture, under moderate glucose (MG) and HG conditions. While the retinal layers of both rodent species displayed a progressively reduced thickness in culture, BCs retained their electrophysiological profiles and remained morphologically identifiable for up to 2 weeks. Responses to glutamate and endogenous inhibitory responses were routinely observed, indicating that the retinal circuitry remained intact during this period. Significant physiological differences between MG and HG conditions were evident in calcium signals and in the time course of responses to glutamate, but the voltage-gated current profiles of BCs displayed only minor variations. Overall, rat retina appeared slightly more sensitive to HG levels compared with mouse. In conclusion, electrophysiological analysis of neuronal function in rodent retinal explants is useful for the study of early damage due to HG neurotoxicity.

Evaluation of retinal function improvement in neovascular age-related macular degeneration after intravitreal aflibercept injections with the use of the assessment of retinal sensitivity: The use of the assessment of retinal sensitivity in anti-VEGF treatment - a STROBE-compliant observational study.

This study compares 2 methods of macular function evaluation: the microperimetric examination (mean central retinal sensitivity and fixation stability) and the distance best-corrected visual acuity (BCVA) examination, which is the most frequently used method of assessing macular function in patients with newly diagnosed wet age-related macular degeneration (AMD) who have been treated with anti-vascular endothelial growth factor (VEGF) drug (aflibercept).Prospective analysis was conducted on 44 eyes of 44 patients treated with intravitreal injection of anti-VEGF (aflibercept) because of newly diagnosed neovascular AMD. According to the research protocol, all patients had a 6-month follow-up. The response to treatment was monitored functionallybyMP-1 microperimetry, fixation, and distance BCVA assessment after injection. Improvement of retinal sensitivity and BCVA was found under aflibercept treatment. There was statistically significant improvement in retinal sensitivity in the MP-1 study 3 and 6 months from the beginning of anti-VEGF therapy. Moreover, a significant improvement in retinal sensitivity between 3 and 6 months of observation was demonstrated. At the same time, up to 3 months from the beginning of treatment, BCVA improved significantly compared to the baseline value. In the 6th month of the study BCVA remained stable without further significant improvement.Microperimetric examination with medium sensitivity and fixation stability assessment is a very valuable test determining the retinal function. It is clear that examining the macular morphology itself in modern diagnostics is not enough to assess retinal function. Microperimetry technique is a valuable tool for functional long-term evaluation of retinal function (also for a period of more than 3 months).

Evolution of retinal changes measured by optical coherence tomography in the assessment of hydroxychloroquine ocular safety in patients with systemic lupus erythematosus.

OBJECTIVE: The objective of this report is to analyse retinal changes over a five-year period, assessed by spectral domain-optical coherence tomography (SD-OCT), in patients from the Lupus-Cruces cohort treated with hydroxychloroquine (HCQ). METHODS: SD-OCT screening was performed annually between 2012 and 2017. Average macular thickness (AMT), ganglion cell layer thickness (GCLT) and qualitative data of retinal pigment epithelium (RPE) and external retina (ExtR) were collected prospectively. We compared data from 2012 (first) and 2017 (second) SD-OCT. RESULTS: We studied 110 patients and 195 eyes. No cases of HCQ toxicity were detected. At the time of the second SD-OCT, 99% patients had taken a daily dose of HCQ ≤5 mg/kg/day. The median time on HCQ was 133 months. The mean AMT and GCLT were significantly lower in both eyes at the second SD-OCT; however, all the differences were clinically insignificant at less than 1%. Qualitative analysis of RPE and ExtR showed no significant changes. Similar results were found among patients with risk factors for retinopathy. The comparison of patients with and without risk factors showed no differences. CONCLUSIONS: This study shows clinically irrelevant retinal changes in an SLE cohort on HCQ treatment over a five-year follow-up. Our findings support the safety of long-term HCQ at doses ≤5 mg/kg/day.

A machine learning approach for automated assessment of retinal vasculature in the oxygen induced retinopathy model.

Preclinical studies of vascular retinal diseases rely on the assessment of developmental dystrophies in the oxygen induced retinopathy rodent model. The quantification of vessel tufts and avascular regions is typically computed manually from flat mounted retinas imaged using fluorescent probes that highlight the vascular network. Such manual measurements are time-consuming and hampered by user variability and bias, thus a rapid and objective method is needed. Here, we introduce a machine learning approach to segment and characterize vascular tufts, delineate the whole vasculature network, and identify and analyze avascular regions. Our quantitative retinal vascular assessment (QuRVA) technique uses a simple machine learning method and morphological analysis to provide reliable computations of vascular density and pathological vascular tuft regions, devoid of user intervention within seconds. We demonstrate the high degree of error and variability of manual segmentations, and designed, coded, and implemented a set of algorithms to perform this task in a fully automated manner. We benchmark and validate the results of our analysis pipeline using the consensus of several manually curated segmentations using commonly used computer tools. The source code of our implementation is released under version 3 of the GNU General Public License ( https://www.mathworks.com/matlabcentral/fileexchange/65699-javimazzaf-qurva ).

Qualitative and Quantitative Assessment of Vascular Changes in Diabetic Macular Edema after Dexamethasone Implant Using Optical Coherence Tomography Angiography.

The aim of this study was to investigate retinal and choriocapillaris vessel changes in diabetic macular edema (DME) after the intravitreal dexamethasone implant (IDI) using optical coherence tomography angiography (OCTA). Moreover, a comparison between morphological and functional parameters of DME and healthy patients was performed. Twenty-five eyes of 25 type 2 diabetic retinopathy patients complicated by macular edema (DME group) and 25 healthy subjects (control group) were enrolled. Superficial capillary plexus density (SCPD) and deep capillary plexus density (DCPD) in the foveal and parafoveal areas, choricapillary density (CCD) and optic disc vessel density (ODVD) were detected using OCTA at baseline and after 7, 30, 60, 90 and 120 days post injection. Best corrected visual acuity (BCVA), retinal sensitivity, and central retinal thickness (CMT) were also evaluated in both groups of patients. A statistically significant difference between the two groups (DME and controls) was found in terms of functional (MP, p < 0.001 and BCVA, p < 0.001) and morphological (CMT, p < 0.001; SCPD in the parafoveal area, p < 0.001; DCPD in the foveal area, p < 0.05 and parafoveal area, p < 0.001; CCD, p < 0.001) parameters. After the treatment, SCPD and DCPD in the foveal and parafoveal areas did not modify significantly during the follow up.

Assessment of Corneal Sensation, Innervation and Retinal Nerve Fiber Layer in Patients Treated with Multiple Intravitreal Ranibizumab Injections.

PURPOSE: To evaluate the effects of repeated intravitreal ranibizumab injections on corneal sensitivity, corneal sub-basal nerve plexus (SBNP) and peripapillary retinal nerve fiber layer (RNFL) thickness in patients with neovascular age-related macular degeneration (AMD). METHODS: Sixty-six eyes of 33 patients who had received unilateral repeated intravitreal ranibizumab injections (0.5 mg/0.05 ml) for the treatment of AMD and 25 eyes of 25 healthy subjects were included in the study. Central corneal sensation was measured using the contact Cochet-Bonnet esthesiometer. The laser scanning in vivo corneal confocal microscope was used to determine corneal SBNP parameters. The peripapillary RNFL thickness was assessed with spectral-domain optical coherence tomography. Data obtained from the ranibizumab-injected eyes were compared with those of the fellow non-treated eyes and the eyes of the healthy control subjects. RESULTS: The mean number of ranibizumab injections per eye was 8.9±5.0 (range 3-20). There were no statistically significant differences in the central corneal sensitivity threshold and corneal SBNP parameters between the ranibizumab-injected eyes and the fellow untreated eyes or between those with neovascular AMD and the healthy control group (P>0.05 for all). The average peripapillary RNFL thickness of the treated eyes did not differ significantly to the fellow eyes (P = 0.237), and the eyes of healthy control subjects (P = 0.918). There were no significant correlations between the number of ranibizumab injections and any of the study parameters. CONCLUSIONS: Multiple intravitreal injections of ranibizumab seem to have no harmful effects on corneal sensitivity, innervation and peripapillary RNFL thickness in patients with AMD.

Noninvasive Electroretinography Assessment of Intravitreal Sustained-Release Methotrexate Microimplants in Rabbit Eyes.

PURPOSE: The purpose of this study is to noninvasively evaluate the safety and toxicity of a chitosan (CS) and polylactic acid (PLA)-based sustained-release methotrexate (MTX) intravitreal microimplant in normal rabbit eyes using electroretinography (ERG). METHODS: PLA-coated CS-based microimplants containing 400 µg of MTX and placebo microimplants (without drug) were surgically implanted in the vitreous of the right and the left eyes, respectively, in each of the 8 New Zealand rabbits using minimally invasive technique. At each predetermined time points (days 5, 12, 19, and 33), ERG was conducted on 2 rabbits to evaluate the safety of the microimplants administered in each eye. ERG was carried out using 2 protocols, scotopic and photopic, on each eye prior to surgery (PS) and prior to euthanasia (PE) conditions. The safety of the microimplants was assessed using statistical analysis of the ERG data (B/A ratio analysis, oscillatory potential analysis, and Naka-Rushton analysis) and subsequently quantifying and comparing functional integrity of the retina between the PS and PE conditions of each eye. RESULTS: Statistical analysis of the ERG data showed no change in retinal functional integrity because of the PLA-coated CS-based MTX microimplant and the placebo microimplant. ERG analysis also revealed absence of any evident bioelectrical dysfunction caused by the microimplants. CONCLUSION: ERGs were performed to determine whether the microimplants containing MTX and the placebo microimplants were associated with any profound retinal bioelectrical dysfunction that might be attributable to toxicity not apparent on histological studies of such eyes. The results shown in this report indicate that there were no such evident adverse effects of the microimplants or contained drug.

Preliminary in vitro and in vivo assessment of a new targeted inhibitor for choroidal neovascularization in age-related macular degeneration.

Choroidal neovascularization (CNV) in age-related macular degeneration usually causes blindness. We established a novel targeted inhibitor for CNV in age-related macular degeneration. The inhibitor CR2-sFlt 1 comprises a CR2-targeting fragment and an anti-vascular endothelial growth factor (VEGF) domain (sFlt 1). The targeting of CR2-sFlt 1 was studied using the transwell assay in vitro and frozen sections in vivo using green fluorescent labeling. Transwell assay results showed that CR2-sFlt 1 migrated to the interface of complement activation products and was present in the retinal tissue of the CR2-sFlt 1-treated CNV mice. Treatment effects were assessed by investigating the VEGF concentration in retinal pigmented epithelial cell medium and the thickness of the CNV complex in the mice treated with CR2-sFlt 1. CR2-sFlt 1 significantly reduced the VEGF secretion from retinal pigmented epithelial cells in vitro and retarded CNV progress in a mouse model. Expression analysis of VEGF and VEGFRs after CR2-sFlt 1 intervention indicated the existence of feedback mechanisms in exogenous CR2-sFlt 1, endogenous VEGF, and VEGFR interaction. In summary, we demonstrated for the first time that using CR2-sFlt 1 could inhibit CNV with clear targeting and high selectivity.

The Role of Multifocal Electroretinography in the Assessment of Drug-Induced Retinopathy: A Review of the Literature.

Multifocal electroretinography (mfERG) is an objective, noninvasive examination for the assessment of visual function. It enables the stimulation of multiple retinal areas simultaneously and recording of each response independently, providing a topographic measure of retinal electrophysiological activity in the central 40-50° of the retina. A clinical application of mfERG represents the assessment of retinal toxicity associated with systemic medications. Drug-induced retinopathy represents a disease that, although not common, requires early recognition: if not detected early, it may progress and cause irreversible retinal dysfunction with subsequent visual impairment. This review aims to evaluate the use of mfERG in the assessment of retinal dysfunction associated with various systemic pharmacological agents based on the currently available literature. The most commonly recognized systemic medications affecting retinal function are included, such as chloroquine and hydroxychloroquine, vigabatrin, deferoxamine, ethambutol, interferon-α, tamoxifen, digoxin, sildenafil, canthaxanthin, amiodarone and nefazodone. The role of mfERG in the early diagnosis of retinal toxicity and the evaluation of disease severity is reviewed, as well as its clinical value in monitoring disease progression or recovery after drug cessation.

Ultrasonographical assessment of implanted biodegradable device for long-term slow release of methotrexate into the vitreous.

Our group has developed a biodegradable drug delivery device (micro-implant) for long-term slow intraocular release of methotrexate (MTX) that can be implanted in the peripheral vitreous. The purpose of this study was to assess the position of the implanted devices and the status of the adjacent vitreous and peripheral retina over time using B-scan ocular ultrasonography (US). In each of the eight New Zealand rabbits used in this study, a chitosan (CS) and poly-lactic acid (PLA)-based micro-implant containing approximately 400 µg of MTX and a placebo micro-implant without MTX were inserted into the peripheral vitreous of the right and left eyes, respective, employing minimally invasive surgery. B-scan US imaging was performed on all of the rabbits immediately after implant insertion and on two rabbits at each of several pre-determined time points post-insertion (post-insertion days 5, 12, 19, and 33) to evaluate the position of the micro-implants and identify any evident morphological changes in the micro-implants and in the peripheral retina and vitreous during treatment. US imaging revealed stable positioning of the PLA-coated CS-based MTX micro-implant and the placebo micro-implant in the respective eyes throughout the study and lack of any changes in size, shape or sonoreflectivity of the micro-implants or abnormalities of the peripheral vitreous or retina in any of the study eyes. In summary, US did not show any evident morphological changes in the micro-implants, shifts in post-insertion position of the micro-implants, or identifiable changes in the micro-implants or peripheral vitreous and retina of the study eyes.

Assessment of vascular regeneration in the CNS using the mouse retina.

The rodent retina is perhaps the most accessible mammalian system in which to investigate neurovascular interplay within the central nervous system (CNS). It is increasingly being recognized that several neurodegenerative diseases such as Alzheimer's, multiple sclerosis, and amyotrophic lateral sclerosis present elements of vascular compromise. In addition, the most prominent causes of blindness in pediatric and working age populations (retinopathy of prematurity and diabetic retinopathy, respectively) are characterized by vascular degeneration and failure of physiological vascular regrowth. The aim of this technical paper is to provide a detailed protocol to study CNS vascular regeneration in the retina. The method can be employed to elucidate molecular mechanisms that lead to failure of vascular growth after ischemic injury. In addition, potential therapeutic modalities to accelerate and restore healthy vascular plexuses can be explored. Findings obtained using the described approach may provide therapeutic avenues for ischemic retinopathies such as that of diabetes or prematurity and possibly benefit other vascular disorders of the CNS.

Intravitreal docosahexaenoic acid in a rabbit model: preclinical safety assessment.

PURPOSE: The purpose of the present study was to evaluate the retinal toxicity of a single dose of intravitreal docosahexaenoic acid (DHA) in rabbit eyes over a short-term period. METHODS: Sixteen New Zealand albino rabbits were selected for this pre-clinical study. Six concentrations of DHA (Brudy Laboratories, Barcelona, Spain) were prepared: 10 mg/50 µl, 5 mg/50 µl, 2'5 mg/50 µl, 50 µg/50 µl, 25 µg/50 µl, and 5 µg/50 µl. Each concentration was injected intravitreally in the right eye of two rabbits. As a control, the vehicle solution was injected in one eye of four animals. Retinal safety was studied by slit-lamp examination, and electroretinography. All the rabbits were euthanized one week after the intravitreal injection of DHA and the eyeballs were processed to morphologic and morphometric histological examination by light microscopy. At the same time aqueous and vitreous humor samples were taken to quantify the concentration of omega-3 acids by gas chromatography. Statistical analysis was performed by SPSS 21.0. RESULTS: Slit-lamp examination revealed an important inflammatory reaction on the anterior chamber of the rabbits injected with the higher concentrations of DHA (10 mg/50 µl, 5 mg/50 µl, 2'5 mg/50 µ) Lower concentrations showed no inflammation. Electroretinography and histological studies showed no significant difference between control and DHA-injected groups except for the group injected with 50 µg/50 µl. CONCLUSIONS: Our results indicate that administration of intravitreal DHA is safe in the albino rabbit model up to the maximum tolerated dose of 25 µg/50 µl. Further studies should be performed in order to evaluate the effect of intravitreal injection of DHA as a treatment, alone or in combination, of different retinal diseases.

Early safety assessment of human oculotoxic drugs using the zebrafish visualmotor response.

INTRODUCTION: Many prescribed drugs can adversely affect the eye by causing damage to the function of visual pathways or toxicity to the retina. Zebrafish have the potential to efficiently predict drugs with adverse ocular effects at pre-clinical stages of development. In this study, we explore the potential of using a semi-automated visual behaviour assay to predict drug-induced ocular toxicity in wild-type zebrafish larvae. METHODS: 3 dpf larvae were treated with six known oculotoxic drugs and five control drugs in embryo medium containing 0.1% DMSO. After 48 h, larvae were assessed using the visualmotor response (VMR), an assay which quantifies locomotor responses to light changes; the optokinetic response (OKR), a behavioural assay that quantifies saccadic eye responses to rotating stimuli; and the touch response, a locomotor response to tactile stimuli. RESULTS: 9 of 10 negative control drugs had no effect on zebrafish visual behaviour. 5 of the 6 known oculotoxic drugs (digoxin, gentamicin, ibuprofen, minoxidil and quinine) showed adverse effects on zebrafish visual behaviour assessed by OKR or the more automated VMR. No gross morphological changes were observed in treated larvae. The general locomotor activity of treated larvae, tested using the touch response assay, showed no differences with respect to controls. Overall the VMR assay had a sensitivity of 83%, a specificity of 100% and a positive predictive value of 100%. DISCUSSION: This study confirms the suitability of the VMR assay as an efficient and predictive pre-clinical approach to evaluate adverse ocular effects of drugs on visual function in vivo.

Polychromatic angiography for the assessment of VEGF-induced BRB dysfunction in the rabbit retina.

PURPOSE: To determine the utility of polychromatic angiography (PCA) in the assessment of VEGF-induced blood retinal barrier (BRB) dysfunction in rabbits. METHODS: Twenty-six eyes of 24 Dutch Belted rabbits were injected intravitreally with 1.25 µg (group A, n = 5), 10 µg (group C, n = 7), or 4 µg (group B, n = 6; group D, n = 4; and group E, n = 4) of VEGF on day 0. Groups D and E were also injected intravitreally with 1.25 µg and 12.5 µg bevacizumab, respectively, on day 2. On days 0, 2, 4, 7, 11, and 14, PCA was performed using a contrast agent mixture composed of fluorescein sodium, indocyanine green, PCM102, and PCM107 and imaged with a modified fundus camera. PCA scores were based on detected leaking fluorophores. RESULTS: On day 7, there was a statistically significant difference between PCA scores of group A (0.6 ± 0.89) and both groups B (2.67 ± 1.37, P = 0.0154) and C (3.33 ± 0.52, P = 0.00085). There was also a statistically significant difference between groups B and E (PCA score 0.75 ± 0.96, P = 0.032) on day 7. On day 11, there was statistically significant difference between group C (1.80 ± 1.1) and both groups A (0, P = 0.021) and B (0.33 ± 0.52, P = 0.037). CONCLUSIONS: A differential response to both increasing VEGF dose and administration of bevacizumab could be discerned using the PCA. PCA allowed stratification of VEGF-induced BRB dysfunction and inhibitory effects of bevacizumab therapy in the rabbit retina.

Impact of the revised american academy of ophthalmology guidelines regarding hydroxychloroquine screening on actual practice.

PURPOSE: To determine the impact of the revised academy guidelines on screening for hydroxychloroquine retinopathy. DESIGN: Retrospective, observational cohort study. METHODS: setting: Private practice of 29 doctors. study population: Total of 183 patients for follow-up and 36 patients for baseline screening. observation procedure: Review of charts, 10-2 visual fields (VFs), multifocal electroretinograms (mfERG), and spectral-domain optical coherence tomography (SD-OCT) images before and after the revised guidelines. main outcome measure: Rates of use of ancillary tests and clinical intervention, costs of screening, follow-up schedules, and comparative sensitivity of tests. RESULTS: New hydroxychloroquine toxicity was found in 2 of 183 returning patients (1.1%). Dosing above 6.5 mg/kg/d was found in 28 of 219 patients (12.8%), an underestimate because patient height, weight, and daily dose were not determined in 77 (35.1%), 84 (38.4%), and 59 (26.9%), respectively. In 10 of the 28 (35.7%), the dose was reduced, in 2 (7.1%) hydroxychloroquine was stopped, but in 16 (57.1%) no action was taken. The cost of screening rose 40%/patient after the revised guidelines. Fundus autofluorescence imaging was not used. No toxicity was detected by adding mfERG or SD-OCT. In no case was a 5-year period free of follow-up recommended after baseline screening in a low-risk patient. CONCLUSIONS: Detection of toxic daily dosing is a cost-effective way to reduce hydroxychloroquine toxicity, but height, weight, and daily dose were commonly not checked. The revised guidelines, emphasizing mfERG, SD-OCT, or FAF, raised screening cost without improving case detection. The recommended 5-year screening-free interval for low-risk patients after baseline examination was ignored.

Optimal preservation of the shark retina for ultrastructural analysis: an assessment of chemical, microwave, and high-pressure freezing fixation techniques.

Recent advances in microwave chemical fixation (MCF) and/or high pressure freezing (HPF) combined with transmission electron microscopy have resulted in superior ultrastructural detail in a variety of tissue types. To date, selachian tissue has been fixed and processed using only standard chemical fixation (CF) methods, and the resulting ultrastructure has been less than ideal. In this study, we compared the ultrastructure of the fragile retinal tissue from the brown banded bamboo shark, Chiloscyllium punctatum, obtained using CF, MCF, and HPF methods. For all fixation protocols, ultrastructural preservation was improved by keeping the tissue in oxygenated Ringer solution until the time of fixation. Both MCF and HPF produced superior retinal ultrastructure compared to conventional CF. Although HPF occasionally resulted in very high quality ultrastructure, microwave fixation was almost comparable, quicker and far more consistent.