Retinal prostheses have shown some clinical success in patients with retinitis pigmentosa and age-related macular degeneration. However, even after the implantation of a retinal prosthesis, the patient’s visual acuity is at best less than 20/420. Reduced visual acuity may be explained by a decrease in the signal-to-noise ratio due to the spontaneous hyperactivity of retinal ganglion cells (RGCs) found in degenerate retinas. Unfortunately, abnormal retinal rewiring, commonly observed in degenerate retinas, has rarely been considered for the development of retinal prostheses. The purpose of this study was to investigate the aberrant retinal network response to electrical stimulation in terms of the spatial distribution of the electrically evoked RGC population. An 8 × 8 multielectrode array was used to measure the spiking activity of the RGC population. RGC spikes were recorded in wild-type [C57BL/6J; P56 (postnatal day 56)], rd1 (P56), rd10 (P14 and P56) mice, and macaque [wild-type and drug-induced retinal degeneration (RD) model] retinas. First, we performed a spike correlation analysis between RGCs to determine RGC connectivity. No correlation was observed between RGCs in the control group, including wild-type mice, rd10 P14 mice, and wild-type macaque retinas. In contrast, for the RD group, including rd1, rd10 P56, and RD macaque retinas, RGCs, up to approximately 400–600 μm apart, were significantly correlated. Moreover, to investigate the RGC population response to electrical stimulation, the number of electrically evoked RGC spikes was measured as a function of the distance between the stimulation and recording electrodes. With an increase in the interelectrode distance, the number of electrically evoked RGC spikes decreased exponentially in the control group. In contrast, electrically evoked RGC spikes were observed throughout the retina in the RD group, regardless of the inter-electrode distance. Taken together, in the degenerate retina, a more strongly coupled retinal network resulted in the widespread distribution of electrically evoked RGC spikes. This finding could explain the low-resolution vision in prosthesis-implanted patients.

We aimed to develop an outer retinal degeneration pig model induced by temporary intravitreal loading of N-methyl-N-nitrosourea (MNU) during vitrectomy. In a preliminary experiment involving 5 mini-pig cases to determine the appropriate concentration of MNU, the vitreous cavity of each eye was filled with 4, 8, 10, 12, or 16 mg/mL MNU for 10 min, which was then replaced with a balanced salt solution. Multimodal examinations including spectral-domain optical coherence tomography (OCT) images and full-field electroretinography (ffERG) were obtained at baseline and week 2, week 6, and week 12. The retinal degeneration was classified according to the amplitudes of a dark adaptive (DA) 10.0 a-wave amplitude. The degree of moderate retinal degeneration was defined as DA 10.0 a-wave amplitude ≥ 10% and < 60% of baseline amplitude. The degree of severe degeneration was defined as DA 10.0 a-wave amplitude < 10% of baseline amplitude, noise, or flat signal. Hematoxylin and eosin staining and immunohistochemistry were performed at week 12. The main experiments were conducted first with 10 cases of 5 mg/mL and later with 13 cases of 10 mg/mL. In the preliminary experiment, degree of outer retinal degeneration increased with MNU concentration. Use of 4, 8, 10, 12, and 16 mg/mL MNU showed no, moderate, severe, severe, and atrophic changes, respectively. In the main experiments, there were 9 cases of moderate retinal degeneration and 1 case of severe degeneration in 5 mg/mL MNU group. Two cases of moderate degeneration and 11 of severe degeneration were recorded in 10 mg/mL group. Mean thickness of total retina, inner nuclear layer, and outer nuclear layer decreased at week 2 in both groups. The mean amplitudes on ffERG decreased at week 2. The ffERG and OCT findings did not change from week 2 to week 6 or week 12. The results of staining supported those of ffERG and OCT. Temporal MNU loading in a vitrectomized pig-eye model induced customized outer retinal degeneration with changing the concentration of MNU.

A single-center retrospective observational case series was conducted. This case series enrolled patients who showed ophthalmic manifestations within one week after COVID-19 vaccination at Korea University Guro Hospital in Seoul, Korea, from May 2021 to January 2022. The medical records of patients who complained of ocular symptoms and showed ophthalmic adverse events within one week after COVID-19 vaccination were reviewed. Seventeen eyes from 16 patients with a mean age of 63.8 (range 33–83) years were included in the case series, and all symptoms developed within 1–7 days following inoculation. Retinal vein occlusion in nine eyes (52.9%), retinal artery occlusion in one eye (5.9%), newly developed anterior uveitis in one eye (5.9%), exacerbation of previously diagnosed panuveitis in two eyes (11.8%), and angle-closure attack with high intraocular pressure in four eyes (23.5%) were included. Twelve patients (75%) had been vaccinated with the AstraZeneca (AZD1222) and four (25%) with the Pfizer (BNT162b2) vaccines. Of these, 10 patients (62.5%) experienced ocular disease exacerbation after the first dose, 4 (25%) after the second dose, and 2 (12.5%) after the third dose (booster shot). Eleven patients (64.7%) underwent tests for hematological abnormalities, and three of them tested positive for anti-PF4 antibodies, but no abnormal findings were noted. A causal relationship between vaccination and the ocular manifestations could not be determined, which is a limitation of this study. However, clinicians should consider the effect of COVID-19 vaccination on ophthalmic disease. Further studies are required to elucidate the possible effects of COVID-19 vaccination on the eye.

ImportanceFungal endophthalmitis caused by contaminated medical products is extremely rare; it follows an intractable clinical course with a poor visual prognosis.ObjectiveTo report the epidemiologic and clinical features and treatment outcomes of a nationwide fungal endophthalmitis outbreak after cataract surgery as a result of contaminated viscoelastic agents in South Korea.Design, Setting, and ParticipantsThis was a retrospective case series analysis of clinical data from multiple institutions in South Korea conducted from September 1, 2020, to October 31, 2021. Data were collected through nationwide surveys in May and October 2021 from the 100 members of the Korean Retinal Society. Patients were diagnosed with fungal endophthalmitis resulting from the use of the viscoelastic material sodium hyaluronate (Unial [Unimed Pharmaceutical Inc]). Data were analyzed from November 1, 2021, to May 30, 2022.Main Outcomes and MeasuresThe clinical features and causative species were identified, and treatment outcomes were analyzed for patients who underwent 6 months of follow-up.ResultsThe fungal endophthalmitis outbreak developed between September 1, 2020, and June 30, 2021, and peaked in November 2020. An official investigation by the Korea Disease Control and Prevention Agency confirmed contamination of viscoelastic material. All 281 eyes of 265 patients (mean [SD] age, 65.4 [10.8] years; 153 female individuals [57.7%]) were diagnosed with fungal endophthalmitis, based on clinical examinations and supportive culture results. The mean (SD) time period between cataract surgery and diagnosis was 24.7 (17.3) days. Patients exhibited characteristic clinical features of fungal endophthalmitis, including vitreous opacity (212 of 281 [75.4%]), infiltration into the intraocular lens (143 of 281 [50.9%]), and ciliary infiltration (55 of 281 [19.6%]). Cultures were performed in 260 eyes, and fungal presence was confirmed in 103 eyes (39.6%). Among them, Fusarium species were identified in 89 eyes (86.4%). Among the 228 eyes included in the treatment outcome analysis, the mean (SD) best-corrected visual acuity improved from 0.78 (0.74) logMAR (Snellen equivalent, 20/120 [7.3 lines]) to 0.36 (0.49) logMAR (Snellen equivalent, 20/45 [4.9 lines]) at 6 months. Furthermore, disease remission with no signs of fungal endophthalmitis (or cells in the anterior chamber milder than grade 1) was noted in 214 eyes (93.9%).Conclusions and RelevanceThis was a retrospectively reviewed case series of a fungal endophthalmitis outbreak resulting from contaminated viscoelastic material. Findings of this case series study support the potential benefit of prompt, aggressive surgical intervention that may reduce treatment burden and improve prognosis of fungal endophthalmitis caused by contaminated medical products.

No abstract