Abstract: Since the 21st century, the development of corneal tissue engineering technology has been developing rapidly. With the progress of biomaterials, cell culture and tissue engineering technology, tissue engineering cornea has gained great development in both basic scientific research and clinical application. In particular, tissue engineered corneal scaffolds are the core components of tissue engineered corneas. It is the focus of current research on tissue engineering cornea to search for scaffolds with good biocompatibility, high safety and good biomechanical properties. In this paper, the recent research progress of tissue engineering corneal materials is reviewed.
Abstract: Cornea serves as the partial front barrier and major light reflection organ of the eye. The integrity of corneal surface is essential for ocular function. Injuries or congenital diseases could significantly destruct the homeostasis of the ocular surface, especially the microenvironment of limbal epithelial stem cells (LESCs), and will eventually cause dysfunction of corneal regeneration and diminish of LESCs. The loss of LESCs by different reasons are named limbal stem cell deficiency (LSCD), which is one of the leading cause of vision loss worldwide. To restore the corneal surface, LESC transplantation in the form of tissue or cell cultures is currently a viable and promising method to treat LSCD. In this review, we aim to introduce the characters and niche of LESCs, and discuss different aspects of its application in cornea surface reconstruction.
Keywords: Diabetic macular edema (DME); diabetic macular oedema (DMO); anti-vascular endothelial growth factor (anti-VEGF); laser photocoagulation; randomised clinical trials (RCTs); retina; diabetic retinopathy
Abstract: To describe the current aging population in China and globally, especially as it applies to age-related macular degeneration (AMD). To review the current standards of care for treating both wet (exudative) eAMD and dry (atrophic) aAMD. And to introduce a model for experimentation that is based on the Age-Related Eye Disease Study (AREDS) using eye bank tissue. A literature search that outlines current aging populations, standards of clinical treatment as defined by large, multicenter, randomized clinical trials that present level-I data with a low risk for bias. An experimental model system of AMD is presented that enables scientific analysis of AMD pathogenesis by applying grading criteria from the AREDS to human eye bank eyes. Analysis includes proteomic, cellular, and functional genomics. The standard of care for the treatment of eAMD is currently defined by the use of several anti-vascular endothelial growth (anti-VEGF) agents alone or in combination with photodynamic therapy. Monotherapy treatment intervals may be monthly, as needed, or by using a treat-and-extend (TAE) protocol. There are no proven therapies for aAMD. AMD that is phenotypically defined at AREDS level 3, should be managed with the use of anti-oxidant vitamins, lutein/zeaxanthin and zinc (AREDS-2 formulation). By understanding the multiple etiologies in the pathogenesis of AMD (i.e., oxidative stress, inflammation, and genetics), the use of human eye bank tissues graded according to the Minnesota Grading System (MGS) will enable future insights into the pathogenesis of AMD. Initial AMD management is with lifestyle modification such as avoiding smoking, eating a healthy diet and using appropriate vitamin supplements (AREDS-2). For eAMD, anti-VEGF therapies using either pro re nata (PRN) or TAE protocols are recommended, with photodynamic therapy in appropriate cases. New cellular information will direct future, potential therapies and these will originate from experimental models, such as the proposed eye bank model using the MGS, that leverages the prospective AREDS database.
Background: The usage of the light emitting diode (LED) has been increasingly applied in the illumination setting and electronic equipment. However, the effect of LED lights on the retina remains unclear. In this study, we observed and analyzed the impact of white LED lights at different intensities on the function and morphology of rat retinas.
Methods: Thirty-six Sprague-Dawley rats weighing 150–180 g were randomly divided into six groups (n=6 in each group) including a normal control (NC) group, 4 white LED groups at different light intensities (4,000, 6,000, 7,000, and 10,000 lux), and an ultraviolet B (UVB) lighting group (302 nm, 1,000 μw/cm2). After 24 hours of continuous illumination, full-field flash electroretinogram (FERG) and pathological examination were performed in each group.
Results: As revealed by FERG, the impairment of retinal function gradually worsened with the increase of LED light intensity. In contrast, the UVB group had the most severe retinal function impairment. Particularly, the functional damage of rod cells and inner nuclear layer cells was the main FERG finding in each group. In the NC group, the retina had typical morphologies featured by well-defined structures, clearly visible border between the inner and outer segments, and neatly arranged inner and outer nuclear layer cells. After 24 hours of illumination, the inner and outer parts of the retina in the 4,000 lux group were still neatly arranged, along with a clear border; however, the inner and outer nuclear layers were randomly arranged, and some irregular nuclei and cells were lost. The damage of the internal and external retinal segments and the internal and external nuclear layers became more evident in the 6,000 lux group, 7,000 lux group, and 10,000 lux group. The UVB group had a more obviously disordered arrangement of inner and outer nuclear layers and loss of cells.
Conclusions: Continuous exposure to white LED light can cause structural and functional damage to rat retinas, and such damage is related to the intensity of illumination. Therefore, the risk of retinal damage should be considered during LED illumination, and proper LED illumination intensity may help to maintain eye health.
Background: To investigate the effect of sirolimus (SRL) eye drops on acute alkali-burn-induced corneal neovascularization (CNV) and explore its possible mechanism.
Methods: A total of 57 male Sprague-Dawley rats weighing 160–180 g were randomly divided into four groups including a normal control group (NC group, n=12), an untreated alkali-burned model control group (MC group, n=15), a blank eye drop treatment group (BT group, n=15), and an SRL eye drop treatment group (ST group, n=15). Corneal inflammation and CNV were observed and scored under a slit-lamp microscope 3, 7, and 14 days after alkali exposure. Three rats were randomly sacrificed in each group before modeling and 3, 7, 14 days after modeling, and the corneas of right eyes were harvested for Western blotting to compare the expression levels of VEGFR2 and caspase-3.
Results: Corneal inflammation scoring showed that the corneal edema and conjunctival congestion were severe in the MC, BT, and ST groups 1 day after alkali exposure but were alleviated at day 3. The corneal transparency was significantly higher in the ST group than in the MC and BT groups at days 7 (F=9.77, P<0.05) and 14 (F=5.81, P<0.05). At day 1, the corneal limbal vascular network was markedly filled. SNV was obvious at days 3, 7, and 14. The new blood vessels were shorter and sparser in the ST group than in the MC and BT groups, and the CNV scores showed significant differences among these groups (day 3: F=8.60, P<0.05; day 7: F=11.40, P<0.05; and day 14: F=41.59, P<0.01). Western blotting showed that the expressions of VEGFR2 and caspase-3 were low before modeling and showed no significant difference among the different groups (F=0.52, P>0.05; F=0.98, P>0.05). The corneal expression of VEGFR2 became significantly higher in the MC and BT groups than in the ST group 3, 7, and 14 days after alkali exposure, and there were significant differences in relative gray-scale values among these groups (day 3: F=32.16, P<0.01; day 7: F=85.96, P<0.01; day 14: F=57.68, P<0.01). The increase in the corneal expression of caspase-3 was significantly larger in the ST group than in the MC and BT groups at days 3, 7, and 14, and there were significant differences in relative gray-scale values among groups (day 3: F=32.16, P<0.01; day 7: F=53.02, P<0.01; day 14: F=38.67, P<0.01).
Conclusions: SRL eye drops can alleviate acute alkali-burn-induced corneal inflammation and inhibit alkali-burn-induced CNV in rat models. It can reduce VEGFR2 expression and increase caspase-3 expression in the corneal tissue, which may contribute to the inhibition of alkali-burn-induced CNV.
Abstract: To present spectral domain optical coherence tomography (OCT) findings during treatment in a case of acute isolated cilioretinal artery occlusion (CLRAO) reversed with intravenous systemic administration of mannitol and carbogen inhalation. Close monitoring with OCT thickness topographic map and cross section scans, every 12 hours, during treatment and till complete reversal of retinal nerve fiber layer edema. Fundus photography and fluorescein angiography (FFA) were used to illustrate occlusion and recanalization. After 72 hours of therapy, visual acuity improved from counting fingers (CF) to 7/10, Snellen’s chart. Consecutively OCT scans showed that the initial macular edema was gradually restored to typical 72 hours of treatment initiation. FFA performed after treatment confirmed recanalization of the cilioretinal artery. Early intervention with the combined intravenous administration of mannitol and carbogen inhalation can reverse acute onset loss of vision due to CLRAO. The reflectivity of retinal layers differs significantly regarding stages of acute CLRAO. In our case report increased reflectivity of the innermost layers of the retina was illustrated and a corresponding reduction in the outer retina and the retinal pigment epithelium and choriocapillaris layers. Macular thickness follow-up data recorded the course of intracellular edema to normal.
Background: To investigate the microstructural features of parapapillary gamma zone and beta zone and their relationship with three-dimensional optic disc shape in non-myopic eyes.
Methods: This cross-sectional study included 62 non-myopic eyes with parapapillary gamma or beta zone and 70 control eyes. On the spectral domain optical coherent tomography (SD-OCT) images, we measured the area of gamma zone and beta zone, the length of border tissue, and related disc parameters. The disc ovality index, disc rotation degrees around three axes, Bruch’s membrane opening (BMO) ovality ratio were calculated based on the SD-OCT images.
Results: The parapapillary gamma zone composed by externally oblique border tissue was found in inferior, nasal and temporal quadrants of the non-myopic eyes. The presence of gamma zone in non-myopic eyes was correlated with smaller disc ovality index, larger rotation degree around vertical and horizontal axes, and larger BMO ovality ratio (P<0.001). Compared with the non-temporal gamma zone group, eyes with temporal gamma zone had a longer axial length and rotated more around vertical axes (P<0.001). Multivariate analysis showed that the area of gamma zone was correlated with the disc ovality index (P<0.001). The presence and area of beta zone was correlated with age (P<0.01).
Conclusions: In non-myopic eyes, the parapapillary gamma zone composed by external oblique border tissue was significantly associated with the disc ovality and disc rotations around vertical and horizontal axes. From a biomechanical perspective, parapapillary gamma zone may contribute to the optic disc stability in association with the structure of BMO.
Abstract: Autoimmune retinopathy (AIR) refers to both paraneoplastic and non-paraneoplastic forms of a rare, acquired retinal degeneration thought to be mediated by the production of antiretinal antibodies. However, the mechanisms underlying AIR pathogenesis are incompletely understood, and it remains a diagnosis of exclusion given the lack of definitive testing as well as its protean clinical presentation. This review summarizes the current literature on the epidemiology, diagnosis, and management of AIR, with a focus on non-paraneoplastic disease and the potential role of immunomodulatory therapy. A recent expert consensus statement on diagnosis and management of non-paraneoplastic AIR served as a framework for interpreting the limited data available, a process that was complicated by the small sample sizes, heterogeneity, and retrospective nature of these studies. Additional work is needed to characterize AIR patients on the basis of cytokine and immunogenetic profiling; to establish the pathogenicity of antiretinal antibodies; and to standardize treatment regimens as well as assessment of clinical outcomes.
