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Adjuncts in Vitreoretinal Surgery
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
The ILM may be considered as a supporting membrane for the basal processes of Mueller cells, as well as a delimiting layer [separating posterior hyaloid from the neurosensory retina]. Like other basement membranes, it is acellular and composed predominantly of type 4 collagen. Its thickness varies across the retina and ranges between 2 and 4 µm [being thickest at the parafovea]. It also seems to have an inherent elasticity, so it tends to scroll spontaneously when incised. ILM thickness increases with age, while its elasticity decreases. The idea that ILM peeling may not have any deleterious effect was first observed following surgery for premacular haemorrhage in which the blood was behind the ILM and so had to be removed. There is an increasing trend towards peeling of the ILM as it has been shown to improve the success of macular hole closure, reduce the risk of EMM recurrence, and prevent formation of macular pucker after vitreoretinal surgery for retinal detachment. Although widely discussed, the safety of ILM peeling in patients with diabetic macular edema, vitreomacular traction, myopic foveoschisis, and optic disc pit maculopathy needs further confirmation in prospective trials.
Lutein in Neural Health and Disease
Published in Robert E.C. Wildman, Richard S. Bruno, Handbook of Nutraceuticals and Functional Foods, 2019
The current focus on healthy eating, along with multiple recommendations to consume a diet rich in fruits and vegetables, likely helps to bolster lutein intake in populations adhering to such recommendations. As such, however, studying the effects of lutein-depleted diets is difficult in humans adhering to these recommendations. Although some studies have reported success in administering low-carotenoid diets, compliance is an issue and in some populations, such as infants, consumption of a carotenoid-free diet may be viewed as unethical and oppositional to feeding breastmilk, which contains lutein. A well-studied primate animal model has provided data on the study of short- and long-term effects of lutein depletion across the lifespan. This model has been particularly important for the study of lutein in ocular disease, as nonhuman primates are the only animals with a macular structure closely resembling that in humans. The earliest use of this model described the basic model and study design, where monkeys were raised on normal or xanthophyll-free diets. In this early study, primates consuming the xanthophyll-free diet lacked MP and exhibited multiple abnormalities in the retina, including increased drusen-like bodies within the retinal pigment epithelium (RPE).21 Subsequent reports utilizing this model confirmed no detectable MP in subjects following a xanthophyll-free diet, but also showed that supplementing a portion of the initial subjects with pure lutein and or zeaxanthin (2.2 mg/kg per day) for 24 to 56 weeks resulted in a rapid increase in both serum lutein and zeaxanthin over the first 4 weeks, followed by a leveling off from 16 weeks onward. Peak MP optical density in these supplemented primates increased to a relatively steady level by 24 to 32 weeks in both lutein- and zeaxanthin-fed groups, suggesting that MP density may reach a plateau after a period of supplementation.22 A portion of the supplemented monkeys in this study received acute short-wavelength light exposures in the fovea and parafovea, with results showing that primates fed xanthophyll-free diets had a dip in the RPE cell density profile at the foveal center, rather than exhibiting a normal peak. Supplementation with xanthophylls reversed this abnormality to a more symmetric profile, indicating that RPEs are sensitive to depletion of xanthophylls.23 Utilizing a longer-term supplementation of xanthophylls from 24 to 101 weeks, an isomer of lutein, meso-zeaxanthin, was found to be deposited in the retinas of monkeys supplemented with lutein, although the diet did not contain meso-zeaxanthin. Thus, the discovery of lutein as the precursor of meso-zeaxanthin in the retina was an important finding.24 After long-term xanthophyll deficiency, lutein or zeaxanthin supplementation protected the fovea from blue light–induced damage.25 Lipofuscin accumulation, a marker of RPE cell damage, aging, and retinal disease, was higher in animals fed diets deficient in lutein and zeaxanthin, as well as omega-3 fatty acids. The increase corresponded to a mathematically calculated 12–20 year acceleration in lipofuscin accumulation compared to animals fed a standard diet.26
Analysis of Microvasculature in Children Recovered from COVID-19 Using Swept-Source OCT/OCTA Technology
Published in Ocular Immunology and Inflammation, 2023
Tugba Cetinkaya, Muhammed M. Kurt, Harun Cetinkaya, Cetin Akpolat
The measurements of VD were insignificantly reduced in all quadrants of three retinal layers and choriocapillaris in the COVID-19 group when compared to healthy controls. The mean superficial retinal VD values measured in the fovea and four quadrants of the parafovea are represented in Table 2. Insignificantly lower (but p = 0.012) and parafoveal nasal quadrant (p = 0.014) of the superficial retinal layer in the COVID-19 group when compared to the control group. The mean deep retinal VD measurements obtained from the fovea and four quadrants of the parafovea are represented in Table 3. Similarly, insignificantly lower (but p = 0.026) and parafoveal nasal quadrant (p = 0.029) of the deep retinal layer. The mean outer retinal and choriocapillaris VD measurements were demonstrated and compared between the two groups in Tables 4 and 5, respectively. Similar to the superficial and deep retinal layers, insignificantly lower (but p = 0.025 and p = 0.039) and parafoveal nasal quadrants (p = 0.038 and p = 0.034) of the outer retinal layer and choriocapillaris, respectively, in the COVID-19 groups when compared to the control groups.
Analysis of swept-source optical coherence tomography angiography measurement alterations in adult patients recovered from COVID-19
Published in Clinical and Experimental Optometry, 2022
Tugba Cetinkaya, Muhammed M Kurt, Cetin Akpolat
The mean superficial retinal VD values measured in the fovea and four quadrants of the parafovea were represented in Table 2. All superficial retinal VD measurements were significantly decreased in the COVID-19 group (P < 0.05 for all). The mean deep retinal VD measurements obtained from the fovea and four quadrants of the parafovea were represented in Table 3. All deep retinal VD measurements showed a significant reduction in the COVID-19 group (P < 0.05 for all). The mean choriocapillaris VD measurements were demonstrated and compared between the two groups in Table 4. All VD measurements of the choriocapillaris were also significantly decreased in the COVID-19 group (P < 0.05 for all).
PRPH2-Associated Macular Dystrophy in 4 Family Members with a Novel Mutation
Published in Ophthalmic Genetics, 2022
Hanna Choi, Alan Cloutier, David Lally
The 65-year-old sister was diagnosed with CACD in the right eye and pattern dystrophy in the left eye. Visual acuity was counting fingers at 5 ft. in the right eye and 20/23 in the left eye. Fundus examination showed a round, unifocal atrophic lesion in the central macula of the right eye (Figure 2e). The left eye demonstrated parafoveal yellow lesions with RPE loss and two focal areas of RPE pigmentary changes superotemporally (Figure 2f). SD-OCT showed complete loss of the foveal and parafoveal outer retina and RPE in the right eye (Figure 2e). The left eye showed parafoveal outer retinal disruption, while the RPE was attenuated in the fovea and parafovea (Figure 2f). Macular FAF demonstrated central hypoautoflourence with junctional hyperautofluorescence in the right eye (Figure 2e) and a speckled pattern with a radially and linearly oriented hyper-FAF in the left eye (Figure 2f). The superotemporal RPE changes in the left eye showed hypoautofluorescence (Figure 2f).