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Photoreceptor oil droplets (ODs) are spherical organelles placed most commonly within the inner segment of the cone photoreceptors. Comprising neutral lipids, ODs can be either non-pigmented or pigmented and have been considered optically functional in various studies. Among living amphibians, ODs were only reported to occur in frogs and toads (Anura), while they are absent in salamanders and caecilians. Nonetheless, the limited understanding of their taxonomic distribution in anurans impedes a comprehensive assessment of their evolution and relationship with visual ecology. We studied the retinae of 134 anuran species, extending the knowledge of the distribution of ODs to 46 of the 58 currently recognized families, and providing a new perspective on this group that complements the available information from other vertebrates. The occurrence of ODs in anurans shows a strong phylogenetic signal, and our findings revealed that ODs evolved at least six times during the evolutionary history of the group, independently from other vertebrates. Although no evident correlation was found between OD occurrence, adult habits and diel activity, it is inferred that each independent origin involves distinct scenarios in the evolution of ODs concerning photic habits. Furthermore, our results revealed significant differences in the size of the ODs between nocturnal and arrhythmic anurans relative to the length of the cones' outer segment.

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Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by reduced visual acuity, nystagmus, photophobia, and very poor or absent color vision. Pathogenic variants in six genes encoding proteins composing the cone phototransduction cascade (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2) and of the unfolded protein response (ATF6) have been related to ACHM cases, while CNGA3 and CNGB3 alone are responsible for most cases. Herein, we provide a clinical and molecular overview of 42 Brazilian patients from 38 families affected with ACHM related to biallelic pathogenic variants in the CNGA3 and CNGB3 genes. Patients' genotype and phenotype were retrospectively evaluated. The majority of CNGA3 variants were missense, and the most prevalent CNGB3 variant was c.1148delC (p.Thr383Ilefs*13), resulting in a frameshift and premature stop codon, which is compatible with previous publications in the literature. A novel variant c.1893T>A (p.Tyr631*) in the CNGB3 gene is reported for the first time in this study. A great variability in morphologic findings was observed in our patients, although no consistent correlation with age and disease stage in OCT foveal morphology was found. The better understanding of the genetic variants landscape in the Brazilian population will help in the diagnosis of this disease.

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BACKGROUND: Cerebral malaria (CM) is a severe complication resulting from Plasmodium falciparum infection. This condition has usually been associated with cognitive, behavioural and motor dysfunctions, being the retinopathy the most serious consequence resulting from the disease. The pathophysiological mechanisms underlying this complication remain incompletely understood. Several experimental models of CM have already been developed in order to clarify those mechanisms related to this syndrome. In this context, the present work has been performed to investigate which possible electrophysiological and neurochemistry alterations could be involved in the CM pathology. METHODS: Experimental CM was induced in Plasmodium berghei-infected male and female C57Bl/6 mice. The survival and neurological symptoms of CM were registered. Brains and retina were assayed for TNF levels and NOS2 expression. Electroretinography measurements were recorded to assessed a- and b-wave amplitudes and neurochemicals changes were evaluated by determination of glutamate and glutathione levels by HPLC. RESULTS: Susceptible C57Bl/6 mice infected with ≈ 106 parasitized red blood cells (P. berghei ANKA strain), showed a low parasitaemia, with evident clinical signs as: respiratory failure, ataxia, hemiplegia, and coma followed by animal death. In parallel to the clinical characterization of CM, the retinal electrophysiological analysis showed an intense decrease of a- and-b-wave amplitude associated to cone photoreceptor response only at the 7 days post-infection. Neurochemical results demonstrated that the disease led to a decrease in the glutathione levels with 2 days post inoculation. It was also demonstrated that the increase in the glutathione levels during the infection was followed by the increase in the 3H-glutamate uptake rate (4 and 7 days post-infection), suggesting that CM condition causes an up-regulation of the transporters systems. Furthermore, these findings also highlighted that the electrophysiological and neurochemical alterations occurs in a manner independent on the establishment of an inflammatory response, once tumour necrosis factor levels and inducible nitric oxide synthase expression were altered only in the cerebral tissue but not in the retina. CONCLUSIONS: In summary, these findings indicate for the first time that CM induces neurochemical and electrophysiological impairment in the mice retinal tissue, in a TNF-independent manner.

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ABSTRACT Purpose: The aim of the present study was to use enhanced depth imaging optical coherence tomography (EDI-OCT) to investigate choroidal changes in patients with cone dystrophy (CD) and to correlate these findings with clinical and electroretinography (ERG) findings. Methods: This case-control study included 40 eyes of 20 patients with CD and 40 eyes of 40 age- and refraction-matched healthy individuals. Choroidal thickness (CT) measurements were obtained under the foveal center and at 500 and 1,500 μm from the nasal and temporal regions to the center of the fovea, respectively. EDI-OCT and ERG data were analyzed, and the correlations of CT with the best-corrected visual acuity (BCVA) and the central foveal thickness (CFT) were evaluated. Results: The mean subfoveal CTs in the CD and control groups were 240.70 ± 70.78 and 356.18 ± 48.55 μm, respectively. The subfoveal CT was significantly thinner in patients with CD than in the controls (p<0.001). The patients with CD also had significantly thinner choroids than the controls at each measurement location relative to the fovea (p<0.001). The subfoveal CT in the CD group correlated with CFT (p=0.012), but no significant correlation was found between the subfoveal CT and BCVA or photopic ERG responses. Conclusions: The present study demonstrated a significant thinning of the choroid in patients with CD. EDI-OCT is a useful technique for describing the choroidal changes occurring in CD. Future studies investigating the association between choroidal changes and outer retinal destruction or the disease stage may provide a better understanding of the pathophysiology of CD.

RESUMO Objetivo: O objetivo deste estudo foi a utilização de imagens de tomografia de coerência óptica com profundidade aprimorada (EDI-OCT) para investigar alterações da coroide em pacientes com distrofia de cones (CD) e correlacionar esses achados com os achados clínicos e de eletrorretinografia (ERG). Métodos: Este estudo de caso-controle incluiu 40 olhos de 20 pacientes com CD e 40 olhos de 40 indivíduos saudáveis com idades e refração pareados. As medidas da espessura da coroide (CT) foram obtidas sob o centro foveal e a 500 μm e 1.500 μm de distância do centro da fóvea, nas regiões nasais e temporais. Dados de EDI-OCT e ERG foram analisados e as correlações do CT com a acuidade visual melhor corrigida (BCVA) e da espessura foveal central (CFT) foram realizadas. Resultados: As CTs subfoveais médias nos grupos CD e controle foram 240,70 ± 70,78 μm e 356,18 ± 48,55 μm, respectivamente. A CT subfoveal foi significativamente mais fina em pacientes com CD do que nos controles (p<0,001). Os com CD pacientes apresentaram também coroides significativamente mais finas do que os controles, em cada local de medição em relação à fóvea (p<0,001). A CT subfoveal no grupo CD se correlacionou com o CFT (p=0,012), mas nenhuma correlação significativa foi encontrada entre a CT subfoveal e a acuidade visual ou respostas fotópicas da ERG. Conclusões: O presente estudo demonstrou um afinamento significativo da coroide em pacientes com CD. A EDI-OCT é uma técnica útil para descrever as mudanças que ocorrem na coroide de pacientes com CD. Futuros estudos investigando a associação entre as alterações da coroide e a destruição da retina externa ou estágio da doença irão proporcionar uma melhor compreensão da fisiopatologia da CD.

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