Retinal Site Research Articles

IOCT-guided simulated subretinal injections: a comparison between manual and robot-assisted techniques in an ex-vivo porcine model

The purpose of this study is to compare robot-assisted and manual subretinal injections in terms of successful subretinal blistering, reflux incidences and damage of the retinal pigment epithelium (RPE). Subretinal injection was simulated on 84 ex-vivo porcine eyes with half of the interventions being carried out manually and the other half by controlling a custom-built robot in a master–slave fashion. After pars plana vitrectomy (PPV), the retinal target spot was determined under a LUMERA 700 microscope with microscope-integrated intraoperative optical coherence tomography (iOCT) RESCAN 700 (Carl Zeiss Meditec, Germany). For injection, a 1 ml syringe filled with perfluorocarbon liquid (PFCL) was tipped with a 40-gauge metal cannula (Incyto Co., Ltd., South Korea). In one set of trials, the needle was attached to the robot’s end joint and maneuvered robotically to the retinal target site. In another set of trials, approaching the retina was performed manually. Intraretinal cannula-tip depth was monitored continuously via iOCT. At sufficient depth, PFCL was injected into the subretinal space. iOCT images and fundus video recordings were used to evaluate the surgical outcome. Robotic injections showed more often successful subretinal blistering (73.7% vs. 61.8%, p > 0.05) and a significantly lower incidence of reflux (23.7% vs. 58.8%, p < 0.01). Although larger tip depths were achieved in successful manual trials, RPE penetration occurred in 10.5% of robotic but in 26.5% of manual cases (p > 0.05). In conclusion, significantly less reflux incidences were achieved with the use of a robot. Furthermore, RPE penetrations occurred less and successful blistering more frequently when performing robotic surgery.

New approaches to the treatment of Age-Related Macular Degeneration (AMD)

• Choroid and choriocapillaris are potential important targets of therapy early in AMD . • Macular vasculature pathology, like choriocapillaris flow deficits, can be measured using OCT-A. • Subretinal drusenoid deposits result from biogenesis pathways involved in lipid homeostasis . • How to target (over- or under-express) the HtrA1 gene associated with AMD is controversial. • Optimal gene therapies for AMD depend on retinal delivery site and specificity to retinal cell.

Structure-Function Relationship of Retinal Ganglion Cells in Multiple Sclerosis.

The retinal ganglion cells (RGC) may be considered an easily accessible pathophysiological site of degenerative processes in neurological diseases, such as the RGC damage detectable in multiple sclerosis (MS) patients with (HON) and without a history of optic neuritis (NON). We aimed to assess and interrelate RGC functional and structural damage in different retinal layers and retinal sites. We included 12 NON patients, 11 HON patients and 14 healthy controls for cross-sectional multifocal pattern electroretinography (mfPERG) and optical coherence tomography (OCT) measurements. Amplitude and peak times of the mfPERG were assessed. Macula and disc OCT scans were acquired to determine macular retinal layer and peripapillary retinal nerve fiber layer (pRNFL) thickness. In both HON and NON patients the foveal N2 amplitude of the mfPERG was reduced compared to controls. The parafoveal P1 peak time was significantly reduced in HON only. For OCT, parafoveal (pfGCL) and perifoveal (pGCL) ganglion cell layer thicknesses were decreased in HON vs. controls, while pRNFL in the papillomacular bundle sector (PMB) showed reductions in both NON and HON. As the mfPERG derived N2 originates from RGC axons, these findings suggest foveal axonal dysfunction not only in HON, but also in NON patients.

The acute effect of atropine eye drops on the human full-field electroretinogram.

Atropine eye drops are a common and effective treatment for slowing myopia progression, but the site and mode of action of atropine in controlling myopia are unclear. We investigated the early retinal sites of action of atropine by examining its effects on the human full-field electroretinogram (ffERG). Baseline ffERGs were recorded in both eyes of 24 healthy subjects (mean ± SD: 21.0 ± 2.3years; spherical equivalent refraction, range: + 1.63 to - 0.75 D) using 6 standard ISCEV protocols, 30min after bilateral pupil dilation with 1% Tropicamide. Atropine (1 drop, 0.1%) was then instilled into the non-dominant eye. 24h later, ffERGs were again recorded in both eyes. Ratios (post-atropine: pre-atropine) of dark-adapted (DA) and light-adapted (LA) ffERGs were compared between atropine-treated and control eyes using multivariate repeated measures general linear models. Atropine-treated eyes responded with 14% lower DA3.0 OP (oscillatory potential) amplitude (p = 0.003) and 4% delay in the DA10.0 a-wave peak time (p = 0.00099) compared with control eyes. Amplitudes and peak times were not different between atropine-treated and control eyes for DA0.01, LA3.0, and LA3.0 flicker ERGs. While atropine caused a small (1.26mm2, p = 0.03) extra increase in pupil area in the treated eye, atropine-induced changes in ffERG responses bore no relationship with changes in pupil area (R2 = 2-5%, p > 0.05). The observed changes in oscillatory potentials corroborate previous findings that atropine affects neural activity in the inner retina. However, observed changes to the a-wave suggest that atropine also affects activity in photoreceptors.

Morphometric and topograpical analysis of retinal abnormalities in central serous chorioretinopathy

Objective: Quantitative morphometric and topographic analysis of specific changes of the retina in patients with the acute central serous chorioretinopathy (CSC) based on annotated tomograms.Methods: 39 patients with the acute CSC (44 eyes – 45 scans) were examined. A complex ophthalmological examination was carried out including 3D optical coherence tomography of maculae. The data was uploaded into CVAT. Three classes of pathological changes were differentiated: 1) retinal neuroepi‑ thelium detachment; 2) retinal pigment epithelium alteration; 3) percolation zones. The analysis of topographical localization of changes and their morphological relations were assessed with a programming language Python.Results: A moderate trend towards vertical asymmetry of the neuroepithelial detachment zone with an excess of cumulative distribution in the lower part of the macula was revealed. Retinal pigment epithelium alteration sites and percolation zones demonstrated a relative peak of representation in the upper nasal part of the macula. In 69.9% and 80% of cases, respectively, abnormalities of retinal pigment epithelium and percolation zones were localized within the limits of neuroepithelial detachment. Direct correlation between the area of neuroepithelial detachment and the area of percolation zones; the area of percolation zones and the area of retinal pigment epithelium alteration; the area of neuroepithelial detachment and the area of retinal pigment epithelium alteration.Conclusions: Percolation zones and abnormalities of retinal pigment epithelium demonstrate similar trends in topo‑ graphical localization and quantitative characteristics and are related to the area of neuroepithelial detachment in CSC. Thus, the number of retinal pigment epithelium abnormalities can serve as an indicator of disease severity.

Patients with myeloproliferative neoplasms and high levels of systemic inflammation develop age-related macular degeneration.

BackgroundEpidemiological data show that myeloproliferative neoplasms (MPNs) are associated with increased risk of neovascular age-related macular degeneration (AMD). However, knowledge about the retinal findings in these patients is lacking. This study was conducted to examine retinal ageing and the prevalence of a hallmark of AMD; drusen, in patients with MPNs. Further, we examine the role of chronic systemic inflammation, considered central in both AMD and MPNs.MethodsIn this single-centre cross-sectional study, we consecutively enrolled 200 patients with MPNs. The study was divided into three substudies. Firstly, we obtained colour fundus photographs from all patients to evaluate and compare the prevalence of drusen with the published estimates from three large population-based studies. Secondly, to evaluate age-related changes in the various retinal layers, optical coherence tomography images were obtained from 150 of the patients and compared to a healthy control group, from a previous study. Thirdly, venous blood was sampled from 63 patients to determine the JAK2V617F allele burden and neutrophil-to-lymphocyte ratio (NLR), a marker of systemic inflammation, in MPN patients with and without drusen.FindingsPatients with MPNs had an increased risk of having large drusen compared to the three population-based studies OR 5·7 (95%CI, 4·1–8·0), OR 6·0 (95%CI, 4·2–8·4) and OR 7·0 (95%CI, 5·0–9·7). Also, we found that the retinal site of drusen accumulation - the Bruch's-membrane-retinal-pigment-epithelium-complex was thicker compared to healthy controls, 0·43μm (95%CI 0·17–0·71, p = 0·0014), but there was no sign of accelerated retinal ageing in terms of thinning of the neuroretina. Further, we found that MPN patients with drusen had a higher level of systemic inflammation than MPN patients with no drusen (p = 0·0383).InterpretationPatients with MPNs suffer from accelerated accumulation of subretinal drusen and therefore AMD from an earlier age than healthy individuals. We find that the retinal changes are located only between the neuroretina and the choroidal bloodstream. Further, we find that the drusen accumulation is associated with a higher JAK2V617F allele burden and a higher NLR, suggesting that low-grade chronic inflammation is a part of the pathogenesis of drusen formation and AMD.FundingFight for Sight, Denmark and Region Zealand's research promotion fund.

Modeling and Temperature Control of Retinal Laser Therapy

The development of a noninvasive technique to measure tissue temperature during retinal laser treatment allows feedback control approaches to regulate the temperature rise to desired values. The main challenge is to provide fast and consistent good control performance regardless the uncertainty of the dynamics of the temperature increase at the different irradiated spots on the retina, which is due to the large variance of the retinal light absorption. In this paper, we demonstrate a successful experimental application in ex-vivo of robust H∞ PID control to handle such a control problem. The system input is the applied laser power and its output is the temperature increase. Based on measurements of input-output data, we employ system identification to model the range of the system dynamics at different retinal irradiation sites. Then, we use a loop shaping approach to express the performance specifications of the closed-loop system and we synthesize accordingly the controller using efficient robust H∞ synthesis tools for fixed structure controllers. The experimental implementation of the closed-loop system for tracking different reference temperatures demonstrates the achievement of the control objectives consistently at the different irradiation sites.

Retinal Ganglion Cells Die by Necroptotic Mechanisms in a Site-Specific Manner in a Rat Blunt Ocular Injury Model.

Closed-globe injury can cause visual loss in military and civilian populations, with retinal cell death, including retinal ganglion cell (RGC) degeneration, leading to irreversible blindness. RGC and optic nerve (ON) degeneration after eye or head injury is termed traumatic optic neuropathy (TON). There are currently no treatments for RGC loss, therefore novel therapeutics to prevent RGC death or promote axonal regeneration are a priority. We investigated necroptotic signaling mechanisms in a rat blunt ocular injury model. After bilateral blunt trauma, protein expression and retinal localization of necroptosis pathway members (receptor interacting protein kinase 1, RIPK1; receptor interacting protein kinase 3, RIPK3; and mixed lineage kinase domain like pseudokinase, MLKL) were assessed by Western blot and immunohistochemistry (IHC), and potent necroptosis inhibitor Necrostatin-1s (Nec-1s) was delivered by intravitreal injection to one eye and vehicle to the contralateral eye. RGC and photoreceptor survival were assessed by cell counting and outer nuclear layer (ONL) thickness measurements on histology. The neuroprotective effects of Nec-1s were assessed in primary retinal culture by βIII-tubulin+ RGC cell counts. MLKL protein expression were upregulated at 48 h after injury and MLKL immunolocalised to retinal binding protein with multiple splice (RBPMS)+ RGC, inner nuclear cells and ONL cells, specifically at the retinal injury site. RIPK3 expression did not increase but RIPK3 co-immunolocalised with RBPMS+ RGC in intact and injured retinae. In vitro, a Nec-1s concentration of 0.01 pg/µL was RGC neuroprotective. In the blunt ocular injury rat model, Nec-1s prevented RGC death at the center of the impact site but did not protect against ONL thinning or provide functional restitution. RGC degeneration in our blunt ocular injury model is site-specific, with necroptosis driving death at the center of the focal impact site.

AMPLITUDE LOSS OF THE HIGH-FREQUENCY FLICKER ELECTRORETINOGRAM IN EARLY DIABETIC RETINOPATHY.

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 t < 1.38, P > 0.31); small, nonsignificant response delays for both patient groups were also observed (both t < 1.57, P > 0.12). 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 t > 2.92 and P < 0.01). Response timing at 62.5 Hz did not differ significantly from control for either group (both t < 1.2 and P > 0.39). 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.

Association between subfoveal choroidal thickness and leakage site on fluorescein angiography in Beh\xe7et\u2019s uveitis

This study aimed to clarify the association between the retinal leakage site on fluorescein angiography (FA) and subfoveal choroidal thickness (SCT) measured using enhanced depth imaging optical coherence tomography (EDI-OCT). Twenty-two patients with Behçet’s uveitis were retrospectively selected in this study. They underwent EDI-OCT and FA in both the active and convalescent phases. The associations of the changes between the active and convalescent phases in SCT and in FA leakage in various retinal areas (total retina, peripheral retina, macula, and optic disc) were examined. The changing rates of SCT between the two investigated phases were significantly associated with the changes in total FA leakage scores (y = 1.79X+ 11.7, r2 = 0.210, p < 0.05). Furthermore, the changes in FA leakage scores in the macula were correlated with the changing rates in SCT (y = 3.72X+ 13.9, r2 = 0.219, p < 0.05). By contrast, there were no significant associations between the changes in SCT and those in leakage from the peripheral retina or the optic disc on FA. These findings demonstrate that SCT may reflect macular vasculitis as determined using FA, and SCT measurement could be a non-invasive method to investigate inflammation near the macula in Behçet’s uveitis.

Evolution of the eyes of vipers with and without infrared-sensing pit organs

We examined lens and brille transmittance, photoreceptors, visual pigments, and visual opsin gene sequences of viperid snakes with and without infrared-sensing pit organs. Ocular media transmittance is high in both groups. Contrary to previous reports, small as well as large single cones occur in pit vipers. Non-pit vipers differ from pit vipers in having a twotiered retina, but few taxa have been examined for this poorly understood feature. All vipers sampled express rh1, sws1 and lws visual opsin genes. Opsin spectral tuning varies but not in accordance with the presence/absence of pit organs, and not always as predicted from gene sequences. The visual opsin genes were generally under purifying selection, with positive selection at spectral tuning amino acids in RH1 and SWS1 opsins, and at retinal pocket stabilization sites in RH1 or LWS (and without substantial differences between pit and nonpit vipers). Lack of evidence for sensory trade-off between viperid eyes (in the aspects examined) and pit organs might be explained by the high degree of neural integration of vision and infrared detection; the latter representing an elaboration of an existing sense with addition of a novel sense organ, rather than involving the evolution of a wholly novel sensory system.

Molecular interactions and mutational impact upon rhodopsin (G90→D90) for hindering dark adaptation of eye: A comparative structural level outlook for signaling mechanism in night blindness

For night blindness, a detailed structural exploration of the interactions among G-protein receptor rhodopsin, transducin and arrestin was performed. Rhodopsin is responsible for dim light vision while a point mutation (G90→D90) results in an adverse change in its photo-transduction. The validated 3D models of the three proteins were utilized, and upon mutation and interactions, rhodopsin attained higher stability (evaluated through thermodynamic energy calculations, electrostatic surface potential and solvent accessible area), thereby participating strongly with transducin. Conformational switches in mutated rhodopsin also depicted a firm conformation with few 310 helices accompanied by increased percentage of pure α-helices and sheets. All evaluations were corroborated through paired T-tests. Glu33 (glycosylated unit in the N-terminal zone) of rhodopsin plays a chief role in the overall interaction pattern. Arg69 and Glu33 from wild-type rhodopsin participated in ionic interactions, while the latter set of ionic interaction remained preserved even after mutation. Cys323 (C-terminal residue) and Arg69 formed H-bonds from the wild-type rhodopsin. Cys323 exceptionally supports cellular signaling pattern in the non-mutated situation and for the non-sufferers of night-blindness. Ser297 and Tyr43 from mutated rhodopsin reside in helices and interact with Thr32 of transducin, preserving the steady conformation in activated interacted state, even in the dark. Ser297 lies adjoined to Lys296 (retinal attachment site), which resides in NPXXY motif (an "activation switch" for signal transduction). Thus, the molecular facet for involvement of photo-transduction, which holds a paramount zone in ophthalmology, was dealt with. This might instigate the future prospect for drug discovery to prevent such mutations.

The Association of Age With the Retinal Break Site and Postoperative Visual Acuity in Patients With Macula-off Rhegmatogenous Retinal Detachment

The Association of Age With the Retinal Break Site and Postoperative Visual Acuity in Patients With Macula-off Rhegmatogenous Retinal Detachment

Non-linearities in the Rod and Cone Photoreceptor Inputs to the Afferent Pupil Light Response.

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.

D-Serine Induced by Ocular Hypertension is Associated with Retinal Cell Death

Purpose: The purpose of this study is to investigate the role of free D-serine in the death of retinal cells caused by ocular hypertension.Methods: Adult Wistar rats were used as an experimental model of ocular hypertension. Immunohistochemistry was used to identify the retinal sites and expression patterns of D-serine and serine racemase in the rat retina. The concentrations of free D-serine and L-serine in the retina were measured by two-dimensional high-performance liquid chromatography. Retinal cell death was investigated by Immunohistochemistry.Results: D-serine was expressed on the retinal ganglion cell layer in the retinas of rats with ocular hypertension. A serine racemase was specifically expressed in the retinal ganglion cells. The ratio of free D-/L-serine in the retinas with ocular hypertension was higher than that in the retinas with normal tension. Annexing-V-positive cells were observed in the retinal ganglion cell layer in the retinas of the rats with ocular hypertension, and these cells were also co-localized with D-serine expression.Conclusions: We suspect that the up-regulation of serine racemase expression induced by ocular hypertensionleads to an increase in free D-serine converted from free L-serine in retinal ganglion cells and that retinal cell death is associated with D-serine expression.

Moderate perinatal thyroid hormone insufficiency alters visual system function in adult rats

Thyroid hormone (TH) is critical for many aspects of neurodevelopment and can be disrupted by a variety of environmental contaminants. Sensory systems, including audition and vision are vulnerable to TH insufficiencies, but little data are available on visual system development at less than severe levels of TH deprivation. The goal of the current experiments was to explore dose-response relations between graded levels of TH insufficiency during development and the visual function of adult offspring. Pregnant Long Evans rats received 0 or 3 ppm (Experiment 1), or 0, 1, 2, or 3 ppm (Experiment 2) of propylthiouracil (PTU), an inhibitor of thyroid hormone synthesis, in drinking water from gestation day (GD) 6 to postnatal day (PN) 21. Treatment with PTU caused dose-related reductions of serum T4, with recovery on termination of exposure, and euthyroidism by the time of visual function testing. Tests of retinal (electroretinograms; ERGs) and visual cortex (visual evoked potentials; VEPs) function were assessed in adult offspring. Dark-adapted ERG a-waves, reflecting rod photoreceptors, were increased in amplitude by PTU. Light-adapted green flicker ERGs, reflecting M-cone photoreceptors, were reduced by PTU exposure. UV-flicker ERGs, reflecting S-cones, were not altered. Pattern-elicited VEPs were significantly reduced by 2 and 3 ppm PTU across a range of stimulus contrast values. The slope of VEP amplitude-log contrast functions was reduced by PTU, suggesting impaired visual contrast gain. Visual contrast gain primarily reflects function of visual cortex, and is responsible for adjusting sensitivity of perceptual mechanisms in response to changing visual scenes. The results indicate that moderate levels of pre-and post-natal TH insufficiency led to alterations in visual function of adult rats, including both retinal and visual cortex sites of dysfunction.

Characteristic appearances of fundus autofluorescence in treatment-naive and active polypoidal choroidal vasculopathy: a retrospective study of 170 patients.

To investigate the characteristic appearances of fundus autofluorescence (FAF) in patients with treatment-naive and active polypoidal choroidal vasculopathy (PCV). Cases with the diagnosis of treatment-naive and active PCV from November 2012 to May 2017 at Peking Union Medical College Hospital were retrospectively reviewed. All patients underwent comprehensive ophthalmologic examination. Autofluorescence (AF) findings were described at the retinal sites of the corresponding lesions identified and diagnosed using indocyanine green angiography and spectral-domain optical coherence tomography. One hundred seventy patients with 192 affected eyes were included. The logMAR BCVA of the patients were 0.53 ± 0.28. The six AF patterns of 243 polypoidal lesions were confluent hypo-AF with hyper-AF ring (49.8%), confluent hypo-AF (22.6%), hyper-AF with hypo-AF ring (3.7%), granular hypo-AF (7.0%), blocked hypo-AF due to hemorrhage (8.6%), and polyps without apparent AF changes (8.2%). For 146 branching vascular networks (BVNs), 97.3% were granular hypo-AF, and others were blocked hypo-AF due to hemorrhage. In eyes with treatment-naive and active PCV, the polypoidal lesions and BVNs induce characteristic FAF changes. FAF images provide reliable adjunct reference for the diagnosis of PCV.

Visual Evoked Potentials in Glaucoma and Alzheimer's Disease.

Visual responses to gratings alternating in contrast have been studied in humans and several mammalian species. Previous evidence from human patients and animal models of neurodegeneration has highlighted the importance to record simultaneously the pattern electroretinogram (P-ERG) and visual evoked cortical potentials (VEPs) to investigate retinal and post-retinal sites of neurodegeneration.In view of the increasing importance of research on experimental models of neurodegenerative diseases, we present here the parametric properties of visual evoked responses in animal models of glaucoma and Alzheimer's disease. Glaucomaand Alzheimer's disease (AD) are two distinct multifactorial neurodegenerative and progressive diseases, primarily affecting the elderly.

Tolerance of high and low amounts of PLGA microspheres loaded with mineralocorticoid receptor antagonist in retinal target site

Mineralocorticoid receptor (MR) contributes to retinal/choroidal homeostasis. Excess MR activation has been shown to be involved in pathogenesis of central serous chorioretinopathy (CSCR). Systemic administration of MR antagonist (MRA) reduces subretinal fluid and choroidal vasodilation, and improves the visual acuity in CSCR patients. To achieve long term beneficial effects in the eye while avoiding systemic side-effects, we propose the use of biodegradable spironolactone-loaded poly-lactic-co-glycolic acid (PLGA) microspheres (MSs). In this work we have evaluated the ocular tolerance of MSs containing spironolactone in rat' eyes. As previous step, we have also studied the tolerance of the commercial solution of canrenoate salt, active metabolite of spironolactone. PLGA MSs allowed in vitro sustained release of spironolactone for 30days. Rat eyes injected with high intravitreous concentration of PLGA MSs (10mg/mL) unloaded and loaded with spironolactone maintained intact retinal lamination at 1month. However enhanced glial fibrillary acidic protein immunostaining and activated microglia/macrophages witness retinal stress were observed. ERG also showed impaired photoreceptor function. Intravitreous PLGA MSs concentration of 2mg/mL unloaded and loaded with spironolactone resulted well tolerated. We observed reduced microglial/macrophage activation in rat retina compared to high concentration of MSs with normal retinal function according to ERG. Spironolactone released from low concentration of MSs was active in the rat retina. Low concentration of spironolactone-loaded PLGA MSs could be a safe therapeutic choice for chorioretinal disorders in which illicit MR activation could be pathogenic.

Blood flow velocity and thickness of the choroid in a patient with chorioretinopathy associated with ocular blunt trauma

BackgroundChoroidal circulation hemodynamics in eyes with ocular blunt trauma has not been quantitatively examined yet. We quantitatively examined changes in choroidal blood flow velocity and thickness at the lesion site using laser speckle flowgraphy (LSFG) and enhanced depth imaging optical coherence tomography (EDI-OCT) in a patient with chorioretinopathy associated with ocular blunt trauma.Case presentationA 13-year-old boy developed a chorioretinal lesion with pigmentation extending from the optic disc to the superotemporal side in the right eye after ocular blunt trauma. The patient’s best-corrected visual acuity (BCVA) was 0.2 in the right eye. Indocyanine green angiography showed hypofluorescence from the initial phase, with a decrease of mean blur rate (MBR) on LSFG color map, which corresponded to the chorioretinal lesion. The BCVA and foveal outer retinal morphologic abnormality spontaneously improved during follow-up. MBR and choroidal thickness increased by 23–31% and 13–17 μm at the lesion site and by 11–22% and 33–42 μm at the fovea, respectively, during the 6-month follow-up period after baseline measurements in the affected eye. In contrast, these parameters showed little or no changes at the normal retinal site in the affected eye and the fovea in the fellow eye.ConclusionsCurrent data revealed that both blood flow velocity and thickness in the choroid at the lesion site decreased in the acute stage and subsequently increased together with improvements in visual function and outer retinal morphology. These results suggest that LSFG and EDI-OCT may be useful indices that can noninvasively evaluate activity of choroidal involvement in ocular blunt trauma-associated chorioretinopathy.