Structural and functional retinal changes in patients with type 2 diabetes without diabetic retinopathy.

OBJECTIVE: The characteristics of the early changes in preclinical diabetic retinopathy (DR) are poorly known. This study aimed to analyse the changes in the structure and function of the fundus in diabetic patients without diabetic retinopathy (NDR). METHODS: This prospective study enrolled patients with type 2 diabetes and healthy controls from April to December 2020. Retinal sensitivity was measured by microperimetry. The peripapillary retinal nerve fibre layer (p-RNFL) thickness, macular retinal thickness, and retinal volume were measured by optical coherence tomography (OCT). The vessel density (VD) and perfusion density (PD) of the peripapillary area, as well as the foveal avascular zone (FAZ) area, FAZ perimeter, and FAZ circularity, were measured by optical coherence tomographic angiography (OCTA). RESULTS: A total of 71 cases (100 eyes) were enrolled in the study, including 34 cases (51 eyes) in the NDR group and 37 cases (49 eyes) in the control group. The mean retinal sensitivity was lower in the NDR group than in the control group for all sectors (all p < .001). Compared with controls, the NDR group showed thinner p-RNFL in the T sector (76.24 ± 14.29 vs. 85.47 ± 19.66 µm, p = .035). The NDR group had a thinner retina in the N2 sector (304.55 ± 16.07 vs. 312.02 ± 12.30 µm, p = .010). The PD of DCP was lower in the N2 sector in the NDR group (44.92 ± 11.77 vs. 50.27 ± 6.37%, p = .044). The VD was higher in the NDR group in RPCP-S/N/I, and the PD was higher in the RPCP-S/N (all p < .05). The frequencies of perifoveal capillary drop-out, notched or punched out borders of the superficial FAZ, and loss of smooth contour were all higher in the NDR group (all p < .05). CONCLUSION: The structure (p-RNFL thickness, VD, and PD) and function (retinal sensitivity) display some changes in diabetic patients even if they had not been found to have DR.Key messagesDecreased retinal sensitivity was observed in diabetic patients before the onset of diabetic retinopathy.Compared with the control group, we found the changes in vessel density or perfusion density in a certain area, whether in SCP, DCP, or RPCP in the NDR group.Before the onset of diabetic retinopathy, the structure and function of the retina in diabetic patients had changed.

Genetic analysis of RNF213 p.R4810K variant in non-moyamoya intracranial artery stenosis/occlusion disease in a Chinese population.

OBJECTIVES: RNF213 p.R4810K was identified as a susceptibility variant for moyamoya disease in Asia and non-moyamoya intracranial artery stenosis/occlusion disease in Japan and Korea recently. The occurrence of this variant was evaluated in patients with non-moyamoya intracranial artery stenosis/occlusion disease in China. METHODS: Two study populations were used in this study. One was recruited from the Second Hospital of Hebei Medical University from April 2015 to May 2016. The other was the archived DNA samples of intracranial artery stenosis/occlusion patients in XiangYa Hospital collected in 2014. The occurrence of RNF213 p.R4810K was investigated in a total of 715 patients with non-moyamoya intracranial artery stenosis/occlusion disease. The carrier rate of RNF213 p.R4810K in 507 normal individuals was used as control. RESULTS: Six of 715 patients (0.84%) with non-moyamoya intracranial artery stenosis/occlusion disease and 2 of the 507 normal controls (0.39%) had RNF213 p.R4810K variant. The carrier rate of RNF213 p.R4810K was higher in non-moyamoya intracranial artery stenosis/occlusion group than that in the normal group. However, no statistically significant association was observed (Odds ratio, 2.14; 95% confidence interval, 0.43-10.63; p = 0.56). CONCLUSIONS: The carrier rate of RNF213 p.R4810K in Chinese non-moyamoya intracranial artery stenosis/occlusion disease patients was significantly lower than that in Korea or Japan. Genetic heterogeneity was highly indicated. Further systematic genetic epidemiology studies with emphasis on Chinese-specific genetic variants and environmental risk factors of intracranial artery stenosis/occlusion disease in larger population are needed.

Effects of posterior corneal astigmatism on the accuracy of AcrySof toric intraocular lens astigmatism correction.

AIM: To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism. METHODS: Fifty-seven patients with toric intraocular lens (IOL) implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study. The keratometric astigmatism (KA) and total corneal astigmatism (TA) were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation. Toric IOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements. Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis. The cylindrical power of toric IOLs was estimated in all eyes. RESULTS: In all cases, the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant. Of a total of 57 cases, the 50.88% decreased from Tn to Tn-1, and 10.53% decreased from Tn to Tn-2. In all cases, 5.26% increased from Tn to Tn+1. The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group. CONCLUSION: The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera.

Optical performance of toric intraocular lenses in the presence of decentration.

AIM: To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned. METHODS: Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance. RESULTS: Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs. CONCLUSIONS: Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.

Therapeutic potential of semaphorin 3E for the treatment of choroidal neovascularization.

PURPOSE: We investigated the effects of semaphorin 3E (Sema3E)/PlexinD1 signaling in the development of choroidal neovascularization (CNV) and explored the therapeutic potential of the pathway. METHODS: We used a laser-induced CNV model in the mouse. The expression of Sema3E and PlexinD1 was evaluated with immunohistochemistry, real-time RT-PCR, and Western blotting. After the intravitreal injection of Sema3E, the CNV size was measured on immunostained flat mounts. The CNV size was compared between inducible PlexinD1 homozygous mice and heterozygous knockout mice. RESULTS: The presence of PlexinD1 was confirmed immunohistochemically in the endothelial cells of CNV. The expression of PlexinD1 mRNA was elevated after laser photocoagulation with its peak expression at day 5 (1.72 times, compared to baseline; P < 0.01). The intravitreal injection of recombinant Sema3E decreased the CNV size (16,320.9 ± 8316.0 µm(2) in the control eyes versus 9487.4 ± 4424.1 µm(2) in the eyes administered 0.1-µg Sema3E, P < 0.01). This inhibitory effect of Sema3E in the formation of CNV was canceled in the inducible PlexinD1 knockout mice (24,920.8 ± 24,684.8 µm(2) in homozygous knockout mice and 13,152.6 ± 7973.0 µm(2) in heterozygous knockout mice, P = 0.014). CONCLUSIONS: These results indicate that Sema3E-PlexinD1 signaling is involved in the development of CNV. Stimulation of the pathway has therapeutic potential for CNV. Further studies are needed to evaluate the effects for clinical applications.

Clinical and immunological characterization of paraneoplastic retinopathy.

PURPOSE: To report the clinical and immunological characterization of paraneoplastic retinopathy (PR) and to investigate the association between spectral-domain optical coherence tomography (SDOCT) findings and the targets of autoantibodies in PR. METHODS: We retrospectively enrolled eight patients (age range, 57-85 years; four men and four women) suspected of having PR. All patients underwent comprehensive ophthalmic examinations, including best-corrected visual acuity (BCVA) measurement, slitlamp examinations, kinetic visual field testing with Goldmann perimetry, electroretinography (ERG), fundus photography, fluorescein angiography, fundus autofluorescence (FAF), SDOCT, and serum sample tests (Western blot analysis and immunohistochemistry [IHC]). RESULTS: Three patients had a history of malignant tumors, and four patients were newly diagnosed as having neoplastic tumors (small cell lung carcinoma [SCLC], thymoma, pancreatic neuroendocrine neoplasm, and colon cancer). Another de novo malignancy (SCLC) was detected in a patient with a history of malignancy (bladder cancer and liposarcoma). The BCVA in these patients ranged from hand motion to 1.5. Goldmann perimetry revealed island, ring-shaped, concentric, or central scotoma. All patients showed nonrecordable or reduced amplitude results on ERG. Fluorescein leakage was detected in five patients. Hyperautofluorescence and/or hypoautofluorescence on FAF was detected in six patients. The serum sample tests identified anti-retinal antibodies in all patients. Patients whose serum contained anti-photoreceptor or anti-retinal pigment epithelium antibody on IHC showed damage of the outer retina on SDOCT. CONCLUSIONS: In this case series, PR was associated with a variety of neoplasms and autoantibodies. Spectral-domain OCT can be used to characterize morphologic changes, and the changes were associated with the targets of autoantibodies.

Knockout of ccr2 alleviates photoreceptor cell death in a model of retinitis pigmentosa.

Neuroinflammation involving CC chemokines such as monocyte chemoattractant protein-1 (MCP-1) has been demonstrated in the pathological process of retinitis pigmentosa (RP), an inherited degenerative retinal disease. However, the mechanism of MCP-1 and its receptor CCR2 involvement in the disease remains unclear. To investigate the role of MCP1/CCR2 in RP pathogenesis, ccr2 mutant RP mice (ccr2(-/-) rd10) were created and analyzed. The expression of MCP-1, RANTES, stromal cell-derived factor (SDF-1), and tumor necrosis factor-α (TNF-α) in the retinas of wild-type, rd10, and ccr2(-/-) rd10 mice was analyzed using quantitative RT-PCR. Photoreceptor apoptosis (TUNEL staining) and the number of microglia (positive for the F4/80 antibody) in the retina were examined. Retinal function was assessed using electroretinograms, and the structure of the whole retina was analyzed from images obtained using optical coherence tomography (OCT) and by histological examination. The expression levels of MCP-1, RANTES, and SDF-1 increased with time in the rd10 mice but not in the wild-type mice. Rearing the mice in the dark prevented degeneration and resulted in thicker photoreceptor layers at each time point. In those mice, the peaks of chemokine expression shifted to a later time with degeneration, suggesting that the expression of these chemokines was induced during the progression of degeneration. Although the difference was not so obvious, the retina in the ccr2(-/-) rd10 mice was consistently and significantly thicker than that in the rd10 (ccr2(+/+) rd10) mice at all time points. Rhodopsin gene expression was also higher in the ccr2(-/-) rd10 mice than in rd10 (ccr2(+/+) rd10) mice, suggesting photoreceptor survival in the former. Retinal function was also better preserved in the ccr2(-/-) rd10 mice than in the rd10 mice. The number of microglia in the retinas of the ccr2(-/-) rd10 mice was significantly lower than that in the retinas of the rd10 mice. Interestingly, the MCP-1 induction that was observed in the retinas of the rd10 mice was diminished in the retinas of the ccr2(-/-) rd10 mice. Our results suggest that the MCP-1/CCR2 system plays a role in retinal degeneration in rd mouse retinas. Retinal MCP-1 expression in the rd mouse retina may be partially controlled by ccr2-positive circulating cells.

Outer retinal circular structures in patients with Bietti crystalline retinopathy.

BACKGROUND: Bietti crystalline retinopathy (BCR) is a distinct retinal degenerative disease characterised by retinal degeneration with many yellow-white crystals located mainly at the posterior pole area. Using spectral domain-optical coherence tomography (SD-OCT), the structural change in retina was investigated. METHODS: Patients diagnosed with BCR (n=12), retinitis pigmentosa (RP, n=292) and cone dystrophy (n=16) were included in this study. The authors mainly examined fundus photographs and SD-OCT, infrared and fundus autofluorescence images of these patients. RESULTS: Crystalline deposits were detected in portions of the retinal pigment epithelium that lacked patchy degenerated lesions. SD-OCT revealed that most of the observed crystalline deposits were located adjacent to the inner side of retinal pigment epithelium layer. The change most frequently observed was circular hyper-refractive structures in the outer nuclear layer. Although the structures were considered to be previously reported "tubular formation" or "tubular degeneration", we determined that many of these circular structures were slices of spherical structures and were typically noted in areas suspected of ongoing active degeneration. CONCLUSION: BCR has characteristic structures in the outer nuclear layer. Although the incidence of the structure varies, it may be characteristic of retinal degeneration and can be found in many retinal degenerative diseases.

Low-dose-rate, low-dose irradiation delays neurodegeneration in a model of retinitis pigmentosa.

The existence of radiation hormesis is controversial. Several stimulatory effects of low-dose (LD) radiation have been reported to date; however, the effects on neural tissue or neurodegeneration remain unknown. Here, we show that LD radiation has a neuroprotective effect in mouse models of retinitis pigmentosa, a hereditary, progressive neurodegenerative disease that leads to blindness. Various LD radiation doses were administered to the eyes in a retinal degeneration mouse model, and their pathological and physiological effects were analyzed. LD gamma radiation in a low-dose-rate (LDR) condition rescues photoreceptor cell apoptosis both morphologically and functionally. The greatest effect was observed in a condition using 650 mGy irradiation and a 26 mGy/minute dose rate. Multiple rounds of irradiation strengthened this neuroprotective effect. A characteristic up-regulation (563%) of antioxidative gene peroxiredoxin-2 (Prdx2) in the LDR-LD-irradiated retina was observed compared to the sham-treated control retina. Silencing the Prdx2 using small-interfering RNA administration reduced the LDR-LD rescue effect on the photoreceptors. Our results demonstrate for the first time that LDR-LD irradiation has a biological effect in neural cells of living animals. The results support that radiation exhibits hormesis, and this effect may be applied as a novel therapeutic concept for retinitis pigmentosa and for other progressive neurodegenerative diseases regardless of the mechanism of degeneration involved.