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Purpose: To investigate the peripapillary retinal nerve fiber layer thickness (RNFLT), macular RNFLT, ganglion cell layer (GCL), and inner plexiform layer (IPL) thickness in recovered COVID-19 patients compared to controls. Methods: Patients previously diagnosed with COVID-19 were included, while healthy patients formed the historic control group. All patients underwent an ophthalmological examination, including macular and optic nerve optical coherence tomography. In the case group, socio-demographic data, medical history, and neurological symptoms were collected. Results: One hundred sixty patients were included; 90 recovered COVID-19 patients and 70 controls. COVID-19 patients presented increases in global RNFLT (mean difference 4.3; CI95% 0.8 to 7.7), nasal superior (mean difference 6.9; CI95% 0.4 to 13.4), and nasal inferior (mean difference 10.2; CI95% 2.4 to 18.1) sectors of peripapillary RNFLT. Macular RNFL showed decreases in COVID-19 patients in volume (mean difference −0.05; CI95% −0.08 to −0.02), superior inner (mean difference −1.4; CI95% −2.5 to −0.4), nasal inner (mean difference −1.1; CI95% −1.8 to −0.3), and nasal outer (mean difference −4.7; CI95% −7.0 to −2.4) quadrants. COVID-19 patients presented increased GCL thickness in volume (mean difference 0.04; CI95% 0.01 to 0.07), superior outer (mean difference 2.1; CI95% 0.8 to 3.3), nasal outer (mean difference 2.5; CI95% 1.1 to 4.0), and inferior outer (mean difference1.2; CI95% 0.1 to 2.4) quadrants. COVID-19 patients with anosmia and ageusia presented an increase in peripapillary RNFLT and macular GCL compared to patients without these symptoms. Conclusions: SARS-CoV-2 may affect the optic nerve and cause changes in the retinal layers once the infection has resolved.

Allergic conjunctivitis is a disease of increasing prevalence that affects both children and adults and causes significant deterioration of their quality of life and sometimes irreversible visual damage. There are various forms of the disease, some are allergen-induced such as seasonal and perennial allergic conjunctivitis, giant papillary conjunctivitis, and contact allergic blepharoconjunctivitis, whereas others are not always explained by allergen exposure, such as vernal keratoconjunctivitis and atopic keratoconjunctivitis. We review their clinical course, characteristics, and differential diagnosis, and highlight recent advances in their pathophysiology and treatment.

To evaluate the concentrations of pro-inflammatory cytokines in tear and aqueous humour of patients with primary open-angle glaucoma (POAG), relative to healthy controls. Method: Tear and aqueous humour samples were collected from 29 healthy controls and 27 POAG patients. Twenty-seven inflammatory cytokines were analysed: interleukin (IL)-

We studied short- and long-term effects of intravitreal injection of N-methyl-d-aspartate (NMDA) on melanopsin-containing (m+) and non-melanopsin-containing (Brn3a+) retinal ganglion cells (RGCs). In adult SD-rats, the left eye received a single intravitreal injection of 5µL of 100nM NMDA. At 3 and 15 months, retinal thickness was measured in vivo using Spectral Domain-Optical Coherence Tomography (SD-OCT). Ex vivo analyses were done at 3, 7, or 14 days or 15 months after damage. Whole-mounted retinas were immunolabelled for brain-specific homeobox/POU domain protein 3A (Brn3a) and melanopsin (m), the total number of Brn3a+RGCs and m+RGCs were quantified, and their topography represented. In control retinas, the mean total numbers of Brn3a+RGCs and m+RGCs were 78,903 ± 3572 and 2358 ± 144 (mean ± SD; n = 10), respectively. In the NMDA injected retinas, Brn3a+RGCs numbers diminished to 49%, 28%, 24%, and 19%, at 3, 7, 14 days, and 15 months, respectively. There was no further loss between 7 days and 15 months. The number of immunoidentified m+RGCs decreased significantly at 3 days, recovered between 3 and 7 days, and were back to normal thereafter. OCT measurements revealed a significant thinning of the left retinas at 3 and 15 months. Intravitreal injections of NMDA induced within a week a rapid loss of 72% of Brn3a+RGCs, a transient downregulation of melanopsin expression (but not m+RGC death), and a thinning of the inner retinal layers.

SARS-CoV-2 is a highly transmissible virus that spreads mainly via person-to-person contact through respiratory droplets, or through contact with contaminated objects or surfaces from an infected person. At present we are passing through a phase of slow and painful understanding of the origin, epidemiological profile, clinical spectrum, and risk profile of the virus. To the best of our knowledge there is only limited and contradictory evidence concerning SARS-CoV-2 transmission through other routes. Importantly, the eye may constitute not only a potential site of virus replication but also an alternative transmission route of the virus from the ocular surface to the respiratory and gastrointestinal tract. It is therefore imperative to gain a better insight into the potential ophthalmological transmission route of the virus and establish directions on best practice and future models of care for ophthalmological patients. This review article critically evaluates available evidence on the ophthalmological mode of viral transmission and the value of earlier identification of the virus on the eye. More evidence is urgently needed to better evaluate the need for protective measures and reliable ocular diagnostic tests to diminish further pandemic spread.

To analyze the neuroprotective effects of 7,8-Dihydroxyflavone (DHF) in vivo and ex vivo, adult albino Sprague-Dawley rats were given a left intraorbital optic nerve transection (IONT) and were divided in two groups: One was treated daily with intraperitoneal (ip) DHF (5 mg/kg) (n = 24) and the other (n = 18) received ip vehicle (1% DMSO in 0.9% NaCl) from one day before IONT until processing. At 5, 7, 10, 12, 14, and 21 days (d) after IONT, full field electroretinograms (ERG) were recorded from both experimental and one additional naïve-control group (n = 6). Treated rats were analyzed 7 (n = 14), 14 (n = 14) or 21 d (n = 14) after IONT, and the retinas immune stained against Brn3a, Osteopontin (OPN) and the T-box transcription factor T-brain 2 (Tbr2) to identify surviving retinal ganglion cells (RGCs) (Brn3a+), α-like (OPN+), α-OFF like (OPN+Brn3a+) or M4-like/α-ON sustained RGCs (OPN+Tbr+). Naïve and right treated retinas showed normal ERG recordings. Left vehicle-treated retinas showed decreased amplitudes of the scotopic threshold response (pSTR) (as early as 5 d), the rod b-wave, the mixed response and the cone response (as early as 10 d), which did not recover with time. In these retinas, by day 7 the total numbers of Brn3a+RGCs, OPN+RGCs and OPN+Tbr2+RGCs decreased to less than one half and OPN+Brn3a+RGCs decreased to approximately 0.5%, and Brn3a+RGCs showed a progressive loss with time, while OPN+RGCs and OPN+Tbr2+RGCs did not diminish after seven days. Compared to vehicle-treated, the left DHF-treated retinas showed significantly greater amplitudes of the pSTR, normal b-wave values and significantly greater numbers of OPN+RGCs and OPN+Tbr2+RGCs for up to 14 d and of Brn3a+RGCs for up to 21 days. DHF affords significant rescue of Brn3a+RGCs, OPN+RGCs and OPN+Tbr2+RGCs, but not OPN+Brn3a+RGCs, and preserves functional ERG responses after IONT.

Purpose Thrombotic events (TE) represent one of the major complications of SARS-CoV-2 infection. The objective is to evaluate vessel density (VD) and perfusion density (PD) by optical coherence tomography angiography (OCTA) in COVID-19 patients, and compare the findings with healthy controls. The secondary objective is to evaluate if there are differences in OCTA parameters between COVID-19 patients with and without associated TE. Methods Cross-sectional case-control study that included patients with laboratory-confirmed diagnosis of COVID-19 with and without TE related to the infection and age-matched healthy controls. Ophthalmological examination and OCTA were performed 12 weeks after diagnosis. Demographic data and medical history were collected. Macular OCTA parameters in the superficial retinal plexus were analyzed according to ETDRS sectors. Results Ninety patients were included, 19 (20%) COVID-19 patients with associated TE, 47 (49.5%) COVID-19 patients without TE, and 29 (30.5%) healthy controls. Fifty-three (55.7%) were male, mean age 54.4 (SD 10.2) years. COVID-19 patients presented significantly lower VD than healthy controls: central (p = 0.003), inner ring (p = 0.026), outer ring (p = 0.001). PD was also significantly decreased: outer ring (p = 0.003), full area (p = 0.001). No differences in OCTA parameters were found between COVID-19 patients with and without TE. Conclusions OCTA represents a promising tool for the in vivo assessment of microvascular changes in COVID-19. Patients with SARS-CoV-2 infection show lower VD and PD compared to healthy controls. However, no differences were found between COVID-19 when considering TE. Prospective studies are required to further evaluate the retinal microvascular involvement of SARS-CoV-2 and its impact on the vasculature of other organs.