Decrease of alpha-crystallin A by miR-325-3p in retinal cells under blue light exposure.

Exposure to blue light can lead to retinal degeneration, causing adverse effects on eye health. Although the loss of retinal cells due to blue light exposure has been observed, the precise molecular mechanisms underlying this process remain poorly understood. In this study, we investigate the role of alpha-crystallin A (CRYAA) in neuro-retinal degeneration and their regulation by blue light. We observed significant apoptotic cell death in both the retina of rats and the cultured neuro-retinal cells. The expressions of Cryaa mRNA and protein were significantly downregulated in the retina exposed to blue light. We identified that miR-325-3p reduces Cryaa mRNA and protein by binding to its 3'-untranslated region. Upregulation of miR-325-3p destabilized Cryaa mRNA and suppresses CRYAA, whereas downregulation of miR-325-3p increased both expressions. Blue light-induced neuro-retinal cell death was alleviated by CRYAA overexpression. These results highlight the critical role of Cryaa mRNA and miR-325-3p molecular axis in blue light-induced retinal degeneration. Consequently, targeting CRYAA and miR-325-3p presents a potential strategy for protecting against blue light-induced retinal degeneration.

Protective effect and mechanism of Lycium ruthenicum Murray anthocyanins against retinal damage induced by blue light exposure.

Lycium ruthenicum Murray (LR) is a medicine and edible plant in Northwest China, and L. ruthenicum Murray anthocyanins (LRA) are green antioxidants with various pharmacological activities, such as antioxidant and anti-inflammatory activities. However, the protective effect and mechanism of LRA against retinal damage induced by blue light exposure are poorly understood. This study explored the protective effects and potential mechanisms of LRA on retinal damage induced by blue light exposure in vitro and in vivo. The results showed that LRA could ameliorate oxidative stress injury by activating the antioxidant stress nuclear factor-related factor 2 pathway, promoting the expression of phase II detoxification enzymes (HO-1, NQO1) and endogenous antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), and reducing reactive oxygen species and malondialdehyde levels. Additionally, LRA could inhibit inflammatory response by decreasing the expression of blue light exposure-induced nuclear factor-κB (NF-κB) pathway-related proteins (NF-κB and p-IκBα), as well as interleukin (IL)-6, tumor necrosis factor-α, IL-1ß pro-inflammatory factors and pro-inflammatory chemokine VEGF, and increasing the expression of anti-inflammatory factor IL-10. Furthermore, LRA could ameliorate oxidative stress-induced apoptosis by upregulating Bcl-2 and downregulating Bax and Caspase-3 protein expression. All these results indicate that LRA can be used as an antioxidant dietary supplement for the treatment or prevention of retinal diseases.

Role of inflammation in a rat model of radiation retinopathy.

Radiation retinopathy (RR) is a major side effect of ocular tumor treatment by plaque brachytherapy or proton beam therapy. RR manifests as delayed and progressive microvasculopathy, ischemia and macular edema, ultimately leading to vision loss, neovascular glaucoma, and, in extreme cases, secondary enucleation. Intravitreal anti-VEGF agents, steroids and laser photocoagulation have limited effects on RR. The role of retinal inflammation and its contribution to the microvascular damage occurring in RR remain incompletely understood. To explore cellular and vascular events after irradiation, we analyzed their time course at 1 week, 1 month and 6 months after rat eyes received 45 Gy X-beam photons. Müller glial cells, astrocytes and microglia were rapidly activated, and these markers of retinal inflammation persisted for 6 months after irradiation. This was accompanied by early cell death in the outer retina, which persisted at later time points, leading to retinal thinning. A delayed loss of small retinal capillaries and retinal hypoxia were observed after 6 months, indicating inner blood‒retinal barrier (BRB) alteration but without cell death in the inner retina. Moreover, activated microglial cells invaded the entire retina and surrounded retinal vessels, suggesting the role of inflammation in vascular alteration and in retinal cell death. Radiation also triggered early and persistent invasion of the retinal pigment epithelium by microglia and macrophages, contributing to outer BRB disruption. This study highlights the role of progressive and long-lasting inflammatory mechanisms in RR development and demonstrates the relevance of this rat model to investigate human pathology.

JP4-039, a Mitochondria-Targeted Nitroxide, Mitigates the Effect of Apoptosis and Inflammatory Cell Migration in the Irradiated Mouse Retina.

We hypothesize that the injection of JP4-039, a mitochondria-targeted nitroxide, prior to irradiation of the mouse retina may decrease apoptosis and reduce neutrophil and macrophage migration into the retina. In our study, we aimed to examine the effects of JP4-039 in the mouse retina using fluorescent microscopy, a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and flow cytometry. Forty-five mice and one eye per mouse were used. In Group 1, fluorescent microscopy was used to determine retinal uptake of 10 µL (0.004 mg/µL) of intravitreally injected BODIPY-labeled JP4-039 at 0, 15, and 60 min after injection. In Group 2, the TUNEL assay was performed to investigate the rate of apoptosis after irradiation in addition to JP4-039 injection, compared to controls. In Group 3, flow cytometry was used to determine the extent of inflammatory cell migration into the retina after irradiation in addition to JP4-039 injection, compared to controls. Maximal retinal uptake of JP4-039 was 15 min after intravitreal injection (p < 0.0001). JP4-039-treated eyes had lower levels of retinal apoptosis (35.8 ± 2.5%) than irradiated controls (49.0 ± 2.7%; p = 0.0066) and demonstrated reduced migration of N1 cells (30.7 ± 11.7% vs. 77.7 ± 5.3% controls; p = 0.004) and M1 cells (76.6 ± 4.2 vs. 88.1 ± 3.7% controls, p = 0.04). Pretreatment with intravitreally injected JP4-039 reduced apoptosis and inflammatory cell migration in the irradiated mouse retina, marking the first confirmed effect of this molecule in retinal tissue. Further studies may allow for safety profiling and potential use for patients with radiation retinopathy.

Assessment of gaze direction during head and neck irradiation and dosimetric impact on the retina, macula and papilla in a cohort of 240 patients with paraoptic tumors.

In a prospective cohort of 240 paraoptic tumors patients treated with protons, there was 10° inter-individual gaze angle variability (up to 30°). In a random 21-patient subset with initial CTs versus and adaptive CTs, 6 (28.57 %) patients had at least twice a 10°-difference in their gaze angle, with > 5 Gy difference on the retina/macula or papilla in 2/21 (9.52 %) and 1/21 (4.76 %) based on cumulative dose from rescans, respectively.

Differences between long- and short-wavelength light-induced retinal damage and the role of PARP-1 in retinal injury induced by blue light.

Photobiomodulation (PBM) therapy uses light of different wavelengths to treat various retinal degeneration diseases, but the potential damage to the retina caused by long-term light irradiation is still unclear. This study were designed to detect the difference between long- and short-wavelength light (650-nm red light and 450-nm blue light, 2.55 mW/cm2, reference intensity in PBM)-induced injury. In addition, a comparative study was conducted to investigate the differences in retinal light damage induced by different irradiation protocols (short periods of repeated irradiation and a long period of constant irradiation). Furthermore, the protective role of PARP-1 inhibition on the molecular mechanism of blue light-induced injury was confirmed by a gene knockdown technique or a specific inhibitor through in vitro and in vivo experiments. The results showed that the susceptibility to retinal damage caused by irradiation with long- and short-wavelength light is different. Shorter wavelength lights, such as blue light, induce more severe retinal damage, while the retina exhibits better resistance to longer wavelength lights, such as red light. In addition, repeated irradiation for short periods induces less retinal damage than constant exposure over a long period. PARP-1 plays a critical role in the molecular mechanism of blue light-induced damage in photoreceptors and retina, and inhibiting PARP-1 can significantly protect the retina against blue light damage. This study lays an experimental foundation for assessing the safety of phototherapy products and for developing target drugs to protect the retina from light damage.

Long-term polystyrene nanoparticles exposure reduces electroretinal responses and exacerbates retinal degeneration induced by light exposure.

The impact of plastic pollution on living organisms have gained significant research attention. However, the effects of nanoplastics (NPs) on retina remain unclear. This study aimed to investigate the effect of long-term polystyrene nanoparticles (PS-NPs) exposure on mouse retina. Eight weeks old C57BL/6 J mice were exposed to PS-NPs at the diameter of 100 nm and concentration of 10 mg/L in drinking water for 3 months. PS-NPs were able to penetrate the blood-retina barrier, accumulated at retinal tissue, caused increased oxidative stress level and reduced scotopic electroretinal responses without remarkable structural damage. PS-NPs exposure caused cytotoxicity and reactive oxygen species accumulation in cultured photoreceptor cell. PS-NPs exposure increased oxidative stress level in retinal pigment epithelial (RPE) cells, leading to changes of gene and protein expression indicative of compromised phagocytic activity and cell junction formation. Long-term PS-NPs exposure also aggravated light-induced photoreceptor cell degeneration and retinal inflammation. The transcriptomic profile of PS-NPs-exposed, light-challenged retinal tissue shared similar features with those of age-related macular degeneration (AMD) patients in the activation of complement-mediated phagocytic and proinflammatory responses. Collectively, these findings demonstrated the oxidative stress- and inflammation-mediated detrimental effect of PS-NPs on retinal function, suggested that long-term PS-NPs exposure could be an environmental risk factor contributing to retinal degeneration.

Polydopamine Nanoparticles as Mimicking RPE Melanin for the Protection of Retinal Cells Against Blue Light-Induced Phototoxicity.

Exposure of the eyes to blue light can induce the overproduction of reactive oxygen species (ROS) in the retina and retinal pigment epithelium (RPE) cells, potentially leading to pathological damage of age-related macular degeneration (AMD). While the melanin in RPE cells absorbs blue light and prevents ROS accumulation, the loss and dysfunction of RPE melanin due to age-related changes may contribute to photooxidation toxicity. Herein, a novel approach utilizing a polydopamine-replenishing strategy via a single-dose intravitreal (IVT) injection is presented to protect retinal cells against blue light-induced phototoxicity. To investigate the effects of overexposure to blue light on retinal cells, a blue light exposure Nrf2-deficient mouse model is created, which is susceptible to light-induced retinal lesions. After blue light irradiation, retina degeneration and an overproduction of ROS are observed. The polydopamine-replenishing strategy demonstrated effectiveness in maintaining retinal structural integrity and preventing retina degeneration by reducing ROS production in retinal cells and limiting the phototoxicity of blue light exposure. These findings highlight the potential of polydopamine as a simple and effective replenishment for providing photoprotection against high-energy blue light exposure.

Reduced light exposure mitigates streptozotocin-induced vascular changes and gliosis in diabetic retina by an anti-inflammatory effect and increased retinal cholesterol turnover.

Diabetic retinopathy is not cured efficiently and changes of lifestyle measures may delay early retinal injury in diabetes. The aim of our study was to investigate the effects of reduced daily light exposure on retinal vascular changes in streptozotocin (STZ)-induced model of DM with emphasis on inflammation, Aqp4 expression, visual cycle and cholesterol metabolism-related gene expression in rat retina and RPE. Male Wistar rats were divided into the following groups: 1. control; 2. diabetic group (DM) treated with streptozotocin (100 mg/kg); 3. group exposed to light/dark cycle 6/18 h (6/18); 4. diabetic group exposed to light/dark cycle 6/18 h (DM+6/18). Retinal vascular abnormalities were estimated based on lectin staining, while the expression of genes involved in the visual cycle, cholesterol metabolism, and inflammation was determined by qRT-PCR. Reduced light exposure alleviated vasculopathy, gliosis and the expression of IL-1 and TNF-α in the retina with increased perivascular Aqp4 expression. The expression of genes involved in visual cycle and cholesterol metabolism was significantly up-regulated in RPE in DM+6/18 vs. DM group. In the retina only the expression of APOE was significantly higher in DM+6/18 vs. DM group. Reduced light exposure mitigates vascular changes and gliosis in DM via its anti-inflammatory effect, increased retinal cholesterol turnover and perivascular Aqp4 expression.

Real-Time Cavitation Monitoring During Optical Coherence Tomography Guided Photo-Mediated Ultrasound Therapy of the Retina.

OBJECTIVE: Photo-mediated ultrasound therapy (PUT) is a novel antivascular therapeutic modality based on cavitation-induced bioeffects. During PUT, synergistic combinations of laser pulses and ultrasound bursts are used to remove the targeted microvessels selectively and precisely without harming nearby tissue. In the current study, an integrated system combining PUT and spectral domain optical coherence tomography (SD-OCT) was developed, where the SD-OCT system was used to guide PUT by detecting cavitation in real time in the retina of the eye. METHOD: We first examined the capability of SD-OCT in detecting cavitation on a vascular-mimicking phantom and compared the results with those from a passive cavitation detector. The performance of the integrated system in treatment of choroidal microvessels was then evaluated in rabbit eyes in vivo. RESULTS: During the in vivo PUT experiments, several biomarkers at the subretinal layer in the rabbit eye were identified on OCT images. The findings indicate that, by evaluating biomarkers of treatment effect, real-time SD-OCT monitoring could help to avoid micro-hemorrhage, which is a potential major side effect. CONCLUSION: Real-time OCT monitoring can thus improve the safety and efficiency of PUT in removing the retinal and choroidal microvasculature.

Morphological Biomarkers Related to Visual Acuity in Patients With Radiation Retinopathy Treated With Intravitreal Ranibizumab.

BACKGROUND AND OBJECTIVE: Our objective was to monitor variables via spectral-domain optical coherence tomography (SD-OCT) and identify the most relevant biomarkers related to best-corrected visual acuity (BCVA) in radiation retinopathy (RR). PATIENTS AND METHODS: A post-hoc analysis of the two-year Ranibizumab for Radiation Retinopathy (RRR) trial analyzed vision and OCT parameters including intraretinal fluid, ellipsoid zone (EZ) disruption, retinal pigment epithelium atrophy, hard exudates, retinal hemorrhage, retinal neovascularization, and subfoveal fluid. BCVA and SD-OCT parameters were evaluated by univariate analysis and a mixed-effects model. RESULTS: Forty eyes from the RRR trial were included. Intraretinal cyst vertical size (week 24: P = 0.032; week 48: P = 0.021), neovascularization (week 48: P = 0.028; week 72: P = 0.025), and EZ disruption (week 72: P = 0.029; week 104: P = 0.019) were the clinical parameters most relevant to BCVA by univariate analysis in at least two time points. The mixed-effects model confirmed the relevance of intraretinal cyst vertical size (P = 0.001) and neovascularization (P = 0.001) but not EZ disruption (P = 0.119) over the course of the study. CONCLUSIONS: This study characterizes the course of visual loss in RR by identifying intraretinal cyst vertical size, neovascularization, and EZ disruption as biomarkers of poor BCVA over a span of two years. Larger multicenter studies are needed to confirm these findings. [Ophthalmic Surg Lasers Imaging Retina 2024;55:255-262.].

Light-induced retinal injury enhanced neurotrophins secretion and neurotrophic effect of mesenchymal stem cells in vitro / Lesão de retina induzida por luz aumentou a secreção de neurotrofinas e o efeito neurotrófico das células primordiais mesenquimais in vitro

PURPOSE: To investigate neurotrophins expression and neurotrophic effect change in mesenchymal stem cells (MSCs) under different types of stimulation. METHODS: Rats were exposed in 10,000 lux white light to develop light-induced retinal injury. Supernatants of homogenized retina (SHR), either from normal or light-injured retina, were used to stimulate MSCs. Quantitative real time for polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were conducted for analysis the expression change in basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF) in MSCs after stimulation. Conditioned medium from SHR-stimulated MSCs and control MSCs were collected for evaluation their effect on retinal explants. RESULTS: Supernatants of homogenized retina from light-injured rats significantly promoted neurotrophins secretion from MSCs (p<0.01). Conditioned medium from mesenchymal stem cells stimulated by light-injured SHR significantly reduced DNA fragmentation (p<0.01), up-regulated bcl-2 (p<0.01) and down-regulated bax (p<0.01) in retinal explants, displaying enhanced protective effect. CONCLUSIONS: Light-induced retinal injury is able to enhance neurotrophins secretion from mesenchymal stem cells and promote the neurotrophic effect of mesenchymal stem cells.

OBJETIVO: Investigar a expressão de neurotrofinas e mudança no efeito neurotrófico de células-tronco mesenquimais (MSCs) sob diferentes tipos de estimulação. MÉTODOS: Os ratos foram expostos em 10.000 lux de luz branca para desenvolver a lesão da retina induzida por luz. Os sobrenadantes de homogeneizado de retina (SHR) quer a partir de retina normal ou da lesada por luz, foram usados para estimular as células-tronco mesenquimais. O RT-PCR quantitativa e ELISA foram realizados para análise da alteração de expressão do fator básico de crescimento de fibroblastos (bFGF), do fator neurotrófico derivado do cérebro (BDNF) e do fator neurotrófico ciliar (CNTF) em MSCs após a estimulação. O meio condicionado de células-tronco mesenquimais estimuladas por SHR e controles foram coletadas para avaliação de seu efeito sobre os explantes de retina. RESULTADOS: SHR de retinas de rato lesadas por luz promoveram aumento significativo de secreção de neurotrofinas em MSCs (p<0,01). O meio condicionado de SHR lesado por luz reduziu significativamente a fragmentação do DNA de MSCs (p<0,01), elevação de Bcl-2 (p<0,01) e redução de bax (p<0,01) em explantes de retina, mostrando um aumento do efeito protetor. CONCLUSÕES: A lesão da retina induzidos pela luz é capaz de aumentar a secreção de neurotrofinas e promover o efeito neurotrófico de células-tronco mesenquimais.

Solar retinopathy without abnormal exposure: case report / Retinopatia solar sem exposição anormal: relato de caso

Solar retinopathy is photochemical damage to the retina, usually caused, by direct or indirect solar observation resulting from the use of hallucinogenic drugs, mental disorders or during eclipses. There may be a loss of visual acuity. We report the case of a 38-year-old patient who presented with a clinical diagnosis of solar retinopathy in the left eye, no prior history of sun exposure, normal visual acuity and complaints of metamorphopsia. Optical coherence tomography showed a rupture of the retinal pigment epithelium, confirming class II solar retinopathy. Visual acuity tends to normalize after 3 to 9 months, but not always. Thus, there is a real need to educate people about using eye protection during sun exposure especially given that some people may be highly susceptible to retinal damage, which was presumably the case for this patient. Finally, we note the importance of optical coherence tomography in diagnosing solar retinopathy.

Retinopatia solar é o dano fotoquímico à retina causado, geralmente, pela observação solar, direta ou indireta, devido ao uso de drogas alucinógenas, distúrbios psíquicos ou durante eclipses. Pode haver, ou não, perda de acuidade visual. Relata-se o caso de uma paciente, 38 anos, com quadro de retinopatia solar em olho esquerdo, sem história prévia de exposição solar, apresentando acuidade visual normal e queixa de metamorfopsia. A tomografia de coerência óptica mostrou ruptura do epitélio pigmentar da retina, confirmando retinopatia solar padrão II. A acuidade visual tende a normalizar-se entre 3 a 9 meses, mas nem sempre. Assim, enfatiza-se a necessidade de orientação à população sobre proteção ocular durante exposição solar pela possibilidade de existirem pessoas com susceptibilidade elevada ao dano retiniano, como se presume possa ter ocorrido com esta paciente. Finalmente, destaca-se a importância da tomografia de coerência óptica para o diagnóstico da retinopatia solar.

Retinal incorporation and differentiation of mesenchymal stem cells intravitreally injected in the injured retina of rats / Incorporação e diferenciação retiniana de células tronco mesenquimais intravítreas em ratos

PURPOSE: To evaluate the pattern of retinal integration and differentiation of mesenchymal stem cells (MSCs) injected into the vitreous cavity of rat eyes with retinal injury. METHODS: Adult rat retinas were submitted to laser damage followed by transplantation of DAPI-labeled BM-MSCs grafts. To assess the integration and differentiation of BM-MSCs in laser-injured retina, host retinas were evaluated 2.4 and 8 weeks after injury/transplantation. RESULTS: Our results demonstrated that the grafted cells survived in the retina for at least 8 weeks and almost all BM-MSCs migrated and incorporated into the neural retina, specifically in the outer nuclear layer (ONL), inner nuclear layer (INL) and ganglion cell layer (GCL) while a subset of grafted cells were found in the subretinal space posttransplantation. At 8 weeks immunohistochemical analysis with several retinal specific markers revealed that the majority of the grafted cells expressed rhodopsin, a rod photoreceptor marker, followed by parvalbumin, a marker for bipolar and amacrine cells. A few subsets of cells were able to express a glial marker, glial fibrillary acidic protein. However, grafted cells failed to express pan-cytokeratin, a retinal pigment epithelium marker. CONCLUSIONS: These results suggest the potential of BM-MSCs to differentiate into retinal neurons. Taken together, these findings might be clinically relevant for future mesenchymal stem cell therapy studies concerning retinal degeneration repair.

OBJETIVO: Avaliar o padrão de integração e diferenciação retiniana de células tronco mesenquimais (CTM) injetadas na cavidade vítrea de ratos portadores de lesões retinianas. MÉTODOS: Ratos Wistar adultos foram submetidos a múltiplas lesões retinianas utilizando-se YAG laser e injeção intravítrea de células tronco mesenquimais. A fim de se avaliar a integração e diferenciação retiniana, o tecido retiniano lesado pelo YAG laser / tratado pelas células tronco, foi avaliado 2, 4 e 8 semanas após a lesão. RESULTADOS: As células injetadas na cavidade vítrea sobreviveram na retina por pelo menos 8 semanas e quase todas células tronco mesenquimais migraram e incorporaram-se na retina neural, especificamente nas camadas nucleares externa e interna e camada de células ganglionares. Uma pequena quantidade de células foi encontrada no espaço sub-retiniano. A análise imuno-histoquímica de 8 semanas mostrou que a maioria das células injetadas expressou rodopsina (marcador para fotorreceptores), parvalbumina (marcador para células bipolares e amácrinas), GFAP (marcador de células gliais). As células injetadas não expressaram a pancitoqueratina, que é a marcadora de células do epitélio pigmentar da retina. CONCLUSÕES: Ocorre aparente diferenciação e incorporação de células tronco mesenquimais na retina de ratos após injeção intravitrea destas células.

Estudo experimental da aplicação retiniana do laser infravermelho via transescleral sob condições de baixa visibilidade / Transscleral infrared laser retinal photocoagulation experimental study under low visibility conditions

OBJETIVOS: Pesquisa experimental, com laser de diodo infravermelho, para estimar a segurança, a reprodutibilidade e a permeabilidade da parede ocular à sua atuação clínica, quando aplicado via transescleral, em condições de baixa visibilidade. MÉTODOS: Submetemos olhos de coelhos pigmentados da raça Nova Zelândia à fotocoagulação retiniana por laser de diodo infravermelho. No olho direito, realizamos fotocoagulação via transescleral sob parâmetros de potência e tempo pré-determinados clinicamente. No olho esquerdo, foram repetidos os mesmos valores da potência e tempo usados no olho direito, desta vez, via transpupilar. Imediatamente e após 2 meses, estudos clínicos baseados na retinografia e histopatológicos foram realizados. RESULTADOS: A permeabilidade da parede ocular, quando da aplicação do laser de diodo infravermelho via transescleral, variou entre 58,95 e 63,87 por cento. A média da permeabilidade da parede ocular a 300 mW (63,14 por cento) mostrou-se significativamente superior àquela da permeabilidade da parede ocular encontrada a 500 mW (59,11 por cento), (P<0,05). CONCLUSÕES: Este estudo sugere a existência da relação dose-resposta em relação aos parâmetros empregados na aplicação do laser de diodo infravermelho via transescleral, com permeabilidade da parede ocular mensurável e reprodutível. Nenhuma rotura, hemorragia ou descolamento da retina ou vítreo foi constatado aos exames subseqüentes às aplicações do laser de diodo infravermelho, o que torna o uso da fotocoagulação via transescleral, no modelo experimental, seguro, mesmo sob condições de baixa visibilidade dos meios.

PURPOSE: Retinal photocoagulation under poor visualization condition is often required. Transscleral infrared laser can be used as an alternative to regular transpupillary treatment. Based upon retinographic measurements, we proposed to estimate the reproducibility as well as ocular wall permeability rate for this treatment. Our primary goal was to evaluate whether this technique can deliver adequate photocoagulation at predetermined parameters without direct retinal visualization. METHODS: In New Zealand pigmented rabbits, optimal transscleral infrared diode laser settings were administered to the right eye. With the same parameters, transpupillary photocoagulation was repeated in the left eye. Retinographic and clinical examinations were performed immediately and two months later. RESULTS: Ocular wall permeability rate varied between 58.95 and 63.87 percent. Average permeability using a power of 300 mW (63.14 percent) was found to be higher than that encountered before its enhancement up to 500 mW (59.11 percent), (P<0.05). CONCLUSIONS: Setting parameters showed dose-response effect. No retinal hole or retinal detachment was noticed in any rabbit. Transscleral infrared photocoagulation appeared to be a reproducible and secure method in the experimental model.

Estudo com tomografia de coerência óptica em pacientes com retinopatia solar / Optical coherence tomography study in patients with solar retinopathy

A retinopatia solar é uma afecção ocular que pode ocorrer quando existe observação solar (direta ou indireta) sem proteção adequada. Tradicionalmente, os casos relatados são ligados a comtemplações de eclipses solares em pacientes usuários, ou não, de alucinógenos, rituais religiosos ou distúrbios psiquícos. O achado retiniano típico se constitui em uma lesão branco amarelada localizada na região foveolar. A sua fisiopatogenia tem sido atribuída a ação do comprimento de luz azul do espectro solar (reação fotoquímica). Estudos histopatológicos demonstram a presença de alterações variáveis no epitélio pigmentado e fotorreceptores retinianos em portadores de retinopatia solar. Local: Departamento de Retina e Vítreo do serviço de Oftalmologia da Faculdade de Medicina da Universidade de São Paulo. Objetivo: Descrever dois casos de retinopatia solar aguda avaliados pelo exame de tomografia de coerência óptica (OCT). Método: Avaliação ocular clínica e tomográfica consecutiva em dois pacientes com história recente de retinopatia solar. A tomografia de coer6encia óptica é um novo exame para avaliação da retina, utiliza-se do principio de ondas coerência fazendo cortes tomográficos da retina. O modelo utilizado (OCT-1) foi derivado do protótipo descrito por Hee e colaboradores. Resaultados: Ambos os casos apresentaram história clínica e achados fundoscópicos similares. O exame com tomografia de coerência óptica não demonstrou anormalidadesda área macular em ambos os casos. Conclusão: Mesmo com poucos casos na literatura, é possível que o exame de OCT seja um indicador do prognóstico visual em casos de afecções maculares por retinopatia solar. A ausência de alterações estruturais precoces constatadas nos casos examinados pode ser justificada pelo grau leve de acometimento foveal encontrado.