Age-Related RPE changes in Wildtype C57BL/6J Mice between 2 and 32 Months.

Purpose: This study provides a systematic evaluation of age-related changes in RPE cell structure and function using a morphometric approach. We aim to better capture nuanced predictive changes in cell heterogeneity that reflect loss of RPE integrity during normal aging. Using C57BL6/J mice ranging from P60-P730, we sought to evaluate how regional changes in RPE shape reflect incremental losses in RPE cell function with advancing age. We hypothesize that tracking global morphological changes in RPE is predictive of functional defects over time. Methods: We tested three groups of C57BL/6J mice (young: P60-180; Middle-aged: P365-729; aged: 730+) for function and structural defects using electroretinograms, immunofluorescence, and phagocytosis assays. Results: The largest changes in RPE morphology were evident between the young and aged groups, while the middle-aged group exhibited smaller but notable region-specific differences. We observed a 1.9-fold increase in cytoplasmic alpha-catenin expression specifically in the central-medial region of the eye between the young and aged group. There was an 8-fold increase in subretinal, IBA-1-positive immune cell recruitment and a significant decrease in visual function in aged mice compared to young mice. Functional defects in the RPE corroborated by changes in RPE phagocytotic capacity. Conclusions: The marked increase of cytoplasmic alpha-catenin expression and subretinal immune cell deposition, and decreased visual output coincide with regional changes in RPE cell morphometrics when stratified by age. These cumulative changes in the RPE morphology showed predictive regional patterns of stress associated with loss of RPE integrity.

Failure to mate enhances investment in behaviors that may promote mating reward and impairs the ability to cope with stressors via a subpopulation of Neuropeptide F receptor neurons.

Living in dynamic environments such as the social domain, where interaction with others determines the reproductive success of individuals, requires the ability to recognize opportunities to obtain natural rewards and cope with challenges that are associated with achieving them. As such, actions that promote survival and reproduction are reinforced by the brain reward system, whereas coping with the challenges associated with obtaining these rewards is mediated by stress-response pathways, the activation of which can impair health and shorten lifespan. While much research has been devoted to understanding mechanisms underlying the way by which natural rewards are processed by the reward system, less attention has been given to the consequences of failure to obtain a desirable reward. As a model system to study the impact of failure to obtain a natural reward, we used the well-established courtship suppression paradigm in Drosophila melanogaster as means to induce repeated failures to obtain sexual reward in male flies. We discovered that beyond the known reduction in courtship actions caused by interaction with non-receptive females, repeated failures to mate induce a stress response characterized by persistent motivation to obtain the sexual reward, reduced male-male social interaction, and enhanced aggression. This frustrative-like state caused by the conflict between high motivation to obtain sexual reward and the inability to fulfill their mating drive impairs the capacity of rejected males to tolerate stressors such as starvation and oxidative stress. We further show that sensitivity to starvation and enhanced social arousal is mediated by the disinhibition of a small population of neurons that express receptors for the fly homologue of neuropeptide Y. Our findings demonstrate for the first time the existence of social stress in flies and offers a framework to study mechanisms underlying the crosstalk between reward, stress, and reproduction in a simple nervous system that is highly amenable to genetic manipulation.

Comparison of quantification of intraretinal hard exudates between optical coherence tomography en face image versus fundus photography.

PURPOSE: To compare the quantification of intraretinal hard exudate (HE) using en face optical coherence tomography (OCT) and fundus photography. METHODS: Consecutive en face images and corresponding fundus photographs from 13 eyes of 10 patients with macular edema associated with diabetic retinopathy or Coats' disease were analyzed using the machine-learning-based image analysis tool, "ilastik." RESULTS: The overall measured HE area was greater with en face images than with fundus photos (en face: 0.49 ± 0.35 mm2 vs. fundus photo: 0.34 ± 0.34 mm2, P < 0.001). However, there was an excellent correlation between the two measurements (intraclass correlation coefficient [ICC] = 0.844). There was a negative correlation between HE area and central macular thickness (CMT) (r = -0.292, P = 0.001). However, HE area showed a positive correlation with CMT in the previous several months, especially in eyes treated with anti-vascular endothelial growth factor (VEGF) therapy (CMT 3 months before: r = 0.349, P = 0.001; CMT 4 months before: r = 0.287, P = 0.012). CONCLUSION: Intraretinal HE can be reliably quantified from either en face OCT images or fundus photography with the aid of an interactive machine learning-based image analysis tool. HE area changes lagged several months behind CMT changes, especially in eyes treated with anti-VEGF injections.

Factors affecting optical coherence tomography angiography signal strength index in patients receiving intravitreal injection treatment.

PURPOSE: To investigate the clinical factors affecting optical coherence tomography angiography (OCTA) signal strength index (SSI) and its change after intravitreal injection treatment in patients with retinal disorders. METHODS: OCTA data from 186 eyes of 166 patients with various retinal disorders including age-related macular degeneration, diabetic macular edema (DME), and retinal vein occlusions who received intravitreal injections were analyzed. The associations between SSI and clinical factors, including age, best-corrected visual acuity (BCVA), media opacity severity, and central macular thickness (CMT), were evaluated both before and after injection. RESULTS: After injection, BCVA improved and CMT decreased significantly, and SSI increased significantly (p = 0.030). BCVA showed a significant positive correlation with media opacity severity before and after injection and with CMT only before injection. In the multivariate analysis, age, presence of DME, BCVA, and media opacity severity were negatively associated with SSI both before and after injection, while CMT was negatively associated with SSI only before injection. After injection, a negative correlation was found between SSI change and both BCVA and CMT change. CONCLUSION: Our findings suggest that OCTA SSI is influenced by various clinical factors, including age, visual acuity, media opacity severity, and macular thickening, especially in cases of DME. The results also indicate that SSI may decrease in patients with macular disorders due to the presence of macular edema and the associated decrease in visual acuity. Therefore, it is crucial to consider these factors when interpreting OCTA data and ensure an adequate level of SSI.

Tractional Retinal Detachment in Eyes with Vitreous Hemorrhage and Proliferative Diabetic Retinopathy and Posterior Vitreous Detachment in Fellow Eye.

PURPOSE: To predict the presence of tractional retinal detachment (TRD) in eyes with dense vitreous hemorrhage (VH) and proliferative diabetic retinopathy (PDR) by evaluating the status of posterior vitreous detachment (PVD) in fellow eyes using optical coherence tomography (OCT). METHODS: A total of 44 eyes from 22 patients who underwent vitrectomy due to dense VH with PDR were enrolled. Using OCT, the PVD status in the fellow eye was divided into two groups (incomplete and complete PVD). The incomplete PVD group included eyes without PVD and eyes with partial PVD. B-scan ultrasonography was performed on eyes with dense VH to evaluate the presence of TRD. Both OCT and B-scan images were reviewed by four ophthalmologists (two novices and two experienced), and the interobserver agreement was evaluated. RESULTS: There was a difference in the interobserver agreement regarding the presence of TRD in eyes with dense VH evaluated by B scan between novice and experienced ophthalmologists (novice, κ = 0.421 vs. experienced, κ = 0.814), although there was no difference between novice and experienced ophthalmologists in the interobserver agreement regarding the status of PVD in the fellow eye evaluated by OCT (novice, κ = 1.000 vs. experienced, κ = 1.000). All observed TRD during vitrectomy occurred in eyes with incomplete PVD in the fellow eye. Logistic regression analysis revealed a statistically significant relation between TRD and the age of the patient (odds ratio [OR], 0.874; p = 0.047), and between TRD and incomplete PVD in the fellow eye evaluated by OCT (OR, 13.904; p = 0.042). CONCLUSIONS: Evaluation of the PVD status in the fellow eye using OCT may be a useful predictor for detecting the presence of TRD in eyes with dense VH and PDR.

Intraoral Approach to Fat Grafting Based on the Mimetic Muscle Unit.

BACKGROUND: Recently, the concepts of anatomic-based fat grafting and mid-facial anatomy have been studied. However, there is no clear consensus on the optimal fat grafting technique. We aimed to introduce a novel intraoral approach to fat grafting based on mid-facial mimetic muscles, wherein a substantial amount of fat was injected into appropriate locations to increase patient satisfaction and decrease the need for additional surgical techniques. METHODS: Sixty-four Asian women (mean age, 41.2 y) who had undergone fat grafting through the intraoral approach between 2014 and 2019 were enrolled. We sequentially performed the following steps: fat harvesting, centrifugation, and fat injection. All patients were followed at an outpatient clinic for 6 to 12 months. We obtained photographs of their face before and at 3 and 6 months postoperatively and conducted a 5-point scale questionnaire survey at the 2 time points postoperatively to evaluate the satisfaction of patients and surgeons. We divided the mid-facial areas into malar eminence, infraorbital, and nasolabial fold areas and evaluated the following items: volume consistency, softness, irregularity, and overall satisfaction. RESULTS: Patients reported "satisfactory" for the postoperative results. There were only 2 cases of complication among the 64 cases which resolved spontaneously. The highest and lowest satisfaction were reported for the malar eminence and nasolabial fold areas, respectively. CONCLUSIONS: Fat grafting through the intraoral approach based on the mimetic muscle unit is an effective and safe method for mid-facial rejuvenation.

Approval status and characteristics of work-related musculoskeletal disorders among Korean workers in 2020.

Background: This study aimed to investigate the characteristics of work-related musculoskeletal disorders (WRMSDs) in occupational disease claims and identify patterns of WRMSDs for each body part by industry and occupation. Methods: This study analyzed the raw data of occupational disease claims for musculoskeletal disorders deliberated by the Occupational Disease Decision Committee of the Korea Workers' Compensation & Welfare Service in 2020. The data was classified into 6 body parts with the highest numbers of occupational disease cases by using the complete enumeration data on principal diagnoses and 4 types of subdiagnoses in the raw data. The characteristics and approval rates of WRMSDs by body part, industry and occupation were examined and summarized. Results: A total of 13,015 occupational disease cases for WRMSDs were classified, and lumbar spinal (back) diseases accounted for the largest proportion of claimed diseases, followed by shoulder, elbow, wrist, knee, and neck diseases in a descending order. The occupations with the highest and second highest numbers of occupational disease cases by body part were found to be automobile assemblers and production-related elementary workers for the neck, school meal service workers and cooks for the back, construction frame mold carpenters and school meal service workers for the shoulder, elementary workers in mining and food service workers for the elbow, food service workers and automobile parts assemblers for the wrist, and ship welders and school meal service workers for the knee. Conclusions: This study examined the characteristics and approval status of WRMSDs by body part and occupation. Based on the study results, management strategies for the prevention of WRMSDs should be established regarding occupations with a high risk of WRMSDs for each body part.

Comparative analysis on intaglio surface trueness, wear volume loss of antagonist, and fracture resistance of full-contour monolithic zirconia crown for single-visit dentistry under simulated mastication.

PURPOSE: This analysis aimed to evaluate the intaglio surface trueness, antagonist's wear volume loss, and fracture resistance of full-contour crowns of (Y, Nb)-stabilized fully-sintered zirconia (FSZ), 4 mol% or 5 mol% yttria-stabilized partially sintered zirconia (4YZ or 5YZ) with high-speed sintering. MATERIALS AND METHODS: A total of 42 zirconia crowns were separated into three groups: FSZ, 4YZ, and 5YZ (n = 14). The intaglio surface trueness of the crowns was evaluated at the inner surface, occlusal, margin, and axial areas and reported as root-mean-square, positive and negative average deviation. Half of the specimens were aged for 120,000 cycles in the chewing simulator, and the wear volume loss of antagonist was measured. Before and after chewing, the fracture load was measured for each group. The trueness values were analyzed with Welch's ANOVA, and the wear volume loss with the Kruskal-Wallis tests. Effect of the zirconia type and aging on fracture resistance of crowns was tested using two-way ANOVA. RESULTS: The intaglio surface trueness measured at four different areas of the crown was less than 50 µm, regardless of the type of zirconia. No significant P in wear volume loss of antagonists were detected among the groups (P > .05). Both the type of zirconia and aging showed statistically significant effects on fracture resistance (P < .05). CONCLUSION: The full-contour crowns of FSZ as well as 4YZ or 5YZ with high-speed sintering were clinically acceptable, in terms of intaglio surface trueness, antagonist's wear volume loss, and fracture resistance after simulated mastication.

Evaluation of intaglio surface trueness, wear, and fracture resistance of zirconia crown under simulated mastication: a comparative analysis between subtractive and additive manufacturing.

PURPOSE: This in-vitro analysis aimed to compare the intaglio trueness, the antagonist's wear volume loss, and fracture load of various single-unit zirconia prostheses fabricated by different manufacturing techniques. MATERIALS AND METHODS: Zirconia crowns were prepared into four different groups (n = 14 per group) according to the manufacturing techniques and generations of the materials. The intaglio surface trueness (root-mean-square estimates, RMS) of the crown was measured at the marginal, axial, occlusal, and inner surface areas. Half of the specimens were artificially aged in the chewing simulator with 120,000 cycles, and the antagonist's volume loss after aging was calculated. The fracture load for each crown group was measured before and after hydrothermal aging. The intaglio trueness was evaluated with Welch's ANOVA and the antagonist's volume loss was assessed by the Kruskal-Wallis tests. The effects of manufacturing and aging on the fracture resistance of the tested zirconia crowns were determined by two-way ANOVA. RESULTS: The trueness analysis of the crown intaglio surfaces showed surface deviation (RMS) within 50 µm, regardless of the manufacturing methods (P = .053). After simulated mastication, no significant differences in the volume loss of the antagonists were observed among the zirconia groups (P = .946). The manufacturing methods and simulated chewing had statistically significant effects on the fracture resistance (P < .001). CONCLUSION: The intaglio surface trueness, fracture resistance, and antagonist's wear volume of the additively manufactured 3Y-TZP crown were clinically acceptable, as compared with those of the 4Y- or 5Y-PSZ crowns produced by subtractive milling.

Vogt-Koyanagi-Harada Disease following mRNA-1273 (Moderna) COVID-19 Vaccination.

PURPOSE: To report a case of Vogt-Koyanagi-Harada (VKH) disease following mRNA-1273 (Moderna) COVID-19 vaccination. METHODS: Retrospective case report. RESULTS: A 50-year-old Korean woman developed bilateral serous retinal detachment 35 days after the first dose of COVID-19 mRNA vaccination (mRNA-1273, Moderna). She experienced adverse effects such as erythema and pain at the injection site, headache, myalgia, and allergy symptoms prior to ocular manifestation. She was diagnosed with Vogt-Koyanagi-Harada (VKH) disease. After treatment with oral prednisolone, the serous retinal detachment resolved and vision improved. CONCLUSION: COVID-19 vaccination might be associated with VKH disease development, and the ingredients of the mRNA vaccine or viral peptide encoded by mRNA may have activated the immunological process and induced VKH disease.

Choroidal vascularity index of patients with coronary artery disease.

We investigated the changes in subfoveal choroidal thickness and choroidal vascularity index (CVI) and their relationship with the severity of coronary artery stenosis in patients with cardiovascular risk factors and symptoms suggestive of coronary artery disease (CAD). Ninety patients who underwent coronary angiography (CAG) for evaluation of their coronary artery status and cardiac symptoms were included. Forty-two patients showed no evidence of CAD; 31 patients had one to two vessel disease; and 17 had a triple vessel disease. There were no significant differences in the subfoveal choroidal thickness among the three groups; however, the CVI in the triple vessel disease group was lower than those in the other groups. The CVI values were good predictors of the presence of triple-vessel disease (p = 0.020). Multivariate logistic regression analysis results revealed that male sex (odds ratio 5.4, p = 0.049), hypertension (odds ratio 4.9, p = 0.017), and CVI (%, odds ratio 0.8, p = 0.016) were significant factors associated with the presence of triple vessel disease. Although CVI may not be a sensitive marker for detecting early changes in the coronary artery, it may be helpful in indicating severe CAD.

AICAR upregulates ABCA1/ABCG1 expression in the retinal pigment epithelium and reduces Bruch's membrane lipid deposit in ApoE deficient mice.

The etiology of age-related macular degeneration (AMD) is diverse; however, recent evidence suggests that the lipid metabolism-cholesterol pathway might be associated with the pathophysiology of AMD. The ATP-binding cassette (ABC) transporters, ABCA1 and ABCG1, are essential for the formation of high-density lipoprotein (HDL) and the regulation of macrophage cholesterol efflux. The failure of retinal or retinal pigment epithelium (RPE) cholesterol efflux to remove excess intracellular lipids causes morphological and functional damage to the retina. In this study, we investigated whether treatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMP-activated protein kinase (AMPK) activator, improves RPE cholesterol efflux and Bruch's membrane (BM) lipid deposits. The protein and mRNA levels of ABCA1 and ABCG1 in ARPE-19 cells and retinal and RPE/choroid tissue from apolipoprotein E-deficient (ApoE-/-) mice were evaluated after 24 weeks of AICAR treatment. The cholesterol efflux capacity of ARPE-19 cells and the cholesterol-accepting capacity of apoB-depleted serum from mice were measured. The thickness of the BM and the degree of lipid deposition were evaluated using electron microscopy. AICAR treatment increased the phosphorylation of AMPK and the protein and mRNA expression of ABCA1 and ABCG1 in vitro. It promoted cholesterol efflux from ARPE-19 cells and upregulated the protein and mRNA levels of ABCA1 and ABCG1 in the retina and RPE in vivo. ApoB-depleted serum from the AICAR-treated group showed enhanced cholesterol-accepting capacity. Long-term treatment with AICAR reduced BM thickening and lipid deposition in ApoE-/- mice. In conclusion, AICAR treatment increased the expression of lipid transporters in the retina and RPE in vivo, facilitated intracellular cholesterol efflux from the RPE in vitro, and improved the functionality of HDL to accept cholesterol effluxed from the cell, possibly via AMPK activation. Collectively, these effects might contribute to the improvement of early age-related pathologic changes in the BM. Pharmacological improvement of RPE cholesterol efflux via AMPK activation may be a potential treatment strategy for AMD.

Electrophysiologic and Morphologic Strain Differences in a Low-Dose NaIO3-Induced Retinal Pigment Epithelium Damage Model.

Purpose: We aimed to explore differences in the NaIO3-elicited responses of retinal pigment epithelium (RPE) and other retinal cells associated with mouse strains and dosing regimens. Methods: One dose of NaIO3 at 10 or 15 mg/kg was given intravenously to adult male C57BL/6J and 129/SV-E mice. Control animals were injected with PBS. Morphologic and functional changes were characterized by spectral domain optical coherence tomography, electroretinography, histologic, and immunofluorescence techniques. Results: Injection with 10 mg/kg of NaIO3 did not cause consistent RPE or retinal changes in either strain. Administration of 15 mg/kg of NaIO3 initially induced a large transient increase in scotopic electroretinography a-, b-, and c-wave amplitudes within 12 hours of injection, followed by progressive structural and functional degradation at 3 days after injection in C57BL/6J mice and at 1 week after injection in 129/SV-E mice. RPE cell loss occurred in a large posterior-central lesion with a ring-like transition zone of abnormally shaped cells starting 12 hours after NaIO3 treatment. Conclusions: NaIO3 effects depended on the timing, dosage, and mouse strain. The RPE in the periphery was spared from damage compared with the central RPE. The large transient increase in the electroretinography was remarkable. Translational Relevance: This study is a phase T1 translational research study focusing on the development and validation of a mouse model of RPE damage. It provides a detailed foundation for future research, informing choices of mouse strain, dosage, and time points to establish NaIO3-induced RPE damage.

Genome editing of hPSCs: Recent progress in hPSC-based disease modeling for understanding disease mechanisms.

Generation of proper models for studying human genetic diseases has been hindered until recently by the scarcity of primary cell samples from genetic disease patients and inefficient genetic modification tools. However, recent advances in clustered, regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology and human induced pluripotent stem cells (hiPSCs) have provided an opportunity to explore the function of pathogenic variants and obtain gene-corrected cells for autologous cell therapy. In this chapter, we address recent applications of CRISPR/Cas9 to hiPSCs in genetic diseases, including neurodegenerative, cardiovascular, and rare diseases.

Age-Related Retinal Changes in Wild-Type C57BL/6J Mice Between 2 and 32 Months.

Purpose: The purpose of this study was to extend our understanding of how aging affects normal retina function and morphology in wild-type C57BL/6J mice, by analyzing electrophysiological recordings and in vivo and post mortem anatomy. Methods: Electroretinograms (ERGs), spectral domain optical coherence tomography (SD-OCT), and confocal scanning laser ophthalmoscope (cSLO) in vivo images were obtained from mice between the ages of 2 and 32 months in four groups: group 1 (<0.5 years), group 2 (1.0-1.5 years), group 3 (1.5-2.0 years), and group 4 (>2.0 years). Afterward, mouse bodies and eyes were weighed. Eyes were stained with hematoxylin and eosin (H&E) and cell nuclei were quantified. Results: With aging, mice showed a significant reduction in both a- and b-wave ERG amplitudes in scotopic and photopic conditions. Additionally, total retina and outer nuclear layer (ONL) thickness, as measured by SD-OCT images, were significantly reduced in older groups. The cSLO images showed an increase in auto-fluorescence at the photoreceptor-RPE interface as age increases. H&E cell nuclei quantification showed significant reduction in the ONL in older ages, but no differences in the inner nuclear layer (INL) or ganglion cell layer (GCL). Conclusions: By using multiple age groups and extending the upper age limit of our animals to approximately 2.65 years (P970), we found that natural aging causes negative effects on retinal function and morphology in a gradual, rather than abrupt, process. Future studies should investigate the exact mechanisms that contribute to these gradual declines in order to discover pathways that could potentially serve as therapeutic targets.

Computational Model-Based Estimation of Mouse Eyeball Structure From Two-Dimensional Flatmount Microscopy Images.

Purpose: Retinal pigment epithelial (RPE) cells serve as a supporter for the metabolism and visual function of photoreceptors and a barrier for photoreceptor protection. Morphology dynamics, spatial organization, distribution density, and growth patterns of RPE cells are important for further research on these RPE main functions. To enable such investigations within the authentic eyeball structure, a new method for estimating the three-dimensional (3D) eyeball sphere from two-dimensional tissue flatmount microscopy images was investigated. Methods: An error-correction term was formulated to compensate for the reconstruction error as a result of tissue distortions. The effect of the tissue-distortion error was evaluated by excluding partial data points from the low- and high-latitude zones. The error-correction parameter was learned automatically using a set of samples with the ground truth eyeball diameters measured with noncontact light-emitting diode micrometry at submicron accuracy and precision. Results: The analysis showed that the error-correction term in the reconstruction model is a valid method for modeling tissue distortions in the tissue flatmount preparation steps. With the error-correction model, the average relative error of the estimated eyeball diameter was reduced from 14% to 5%, and the absolute error was reduced from 0.22 to 0.03 mm. Conclusions: A new method for enabling RPE morphometry analysis with respect to locations on an eyeball sphere was created, an important step in increasing RPE research and eye disease diagnosis. Translational Relevance: This method enables one to derive RPE cell information from the 3D eyeball surface and helps characterize eyeball volume growth patterns under diseased conditions.

Aqueous humor inflammatory cytokine levels and choroidal thickness in patients with macular edema associated with branch retinal vein occlusion.

PURPOSE: We aimed to investigate the association between subfoveal choroidal thickness (SCT) and the level of aqueous humor (AH) inflammatory cytokines in patients with macular edema (ME) associated with branch retinal vein occlusion (BRVO). METHODS: Twenty-eight eyes of 28 BRVO ME patients who underwent intravitreal injection treatment (ranibizumab, bevacizumab, or dexamethasone implant) were prospectively recruited. The concentrations of vascular endothelial growth factor (VEGF)-A and inflammatory cytokines were measured from AH samples. We analyzed clinical factors associated with visual gain or the degree of central macular thickness (CMT) decrease and the association between SCT and inflammatory cytokine levels. RESULTS: On multiple linear regression analysis, the AH interleukin (IL)-8 level was significantly associated with visual gain and CMT reduction at 6 months. Age, systemic hypertension, and AH monocyte chemo-attractant protein 1 level showed a significant association with baseline SCT, and VEGF-A showed a significant association with baseline SCT ratio (BRVO eye SCT/fellow eye SCT). Those with thick SCT showed a higher level of AH soluble VEGF receptors 2 and IL-8 and showed better visual gain and greater CMT reduction at 2 and 6 months compared to the thin SCT group. CONCLUSIONS: The level of AH inflammatory cytokines was significantly associated with the ischemic status of the retina, treatment outcomes, and SCT in BRVO ME patients. Thick baseline SCT might be a predictive sign for better treatment outcomes in BRVO ME patients which are thought to be related to a higher level of intraocular inflammatory cytokines in these patients.

Long-term HbA1c variability and the development and progression of diabetic retinopathy in subjects with type 2 diabetes.

This study aimed to investigate whether long-term HbA1c variability is associated with the development and progression of diabetic retinopathy (DR) in subjects with type 2 diabetes. We retrospectively reviewed 434 type 2 diabetes subjects without DR who underwent regular DR screening. We reviewed fundus findings, collected HbA1c levels, and calculated the coefficient of variation (CV) and average real variability (ARV) of each subject's HbA1c level. DR was developed in 55 subjects and progressed to moderate nonproliferative DR or worse DR in 23 subjects. On Cox proportional hazards regression analysis, HbA1c ARV, but not HbA1c CV, was significantly associated with DR development. However, the association between HbA1c variability and the DR progression rate to moderate nonproliferative DR or worse DR was not significant. The inter-visit HbA1c difference value on consecutive examination predicted DR development well and more careful screening for DR is needed for those with an absolute value change of 2.05%, an absolute increase of 1.75%, and an absolute decrease of 1.45% in HbA1c levels on consecutive examination. These results indicate that long-term glucose variability measured by HbA1c ARV might be an independent risk factor for DR development in addition to the mean HbA1c level in early diabetic subjects.

Morphometric Analysis of Retinal Pigment Epithelial Cells From C57BL/6J Mice During Aging.

Purpose: To quantitatively evaluate the changes in orientation and morphometric features of mouse retinal pigment epithelial (RPE) cells in different regions of the eye during aging. Methods: We segmented individual RPE cells from whole RPE flatmount images of C57BL/6J mice (postnatal days 30 to 720) using a machine-learning method and evaluated changes in morphometric features, including our newly developed metric combining alignment and shape of RPE cells during aging. Results: Mainly, the anterior part of the RPE sheet grows during aging, while the posterior part remains constant. Changes in size and shape of the peripheral RPE cells are prominent with aging as cells become larger, elongated, and concave. Conversely, the central RPE cells maintain relatively constant size and numbers with aging. Cell count in the central area and the overall cell count (approximately 50,000) were relatively constant over different age groups. RPE cells also present a specific orientation concordance that matches the shape of the specific region of the eyeball. Those cells near the optic disc or equator have a circumferential orientation to cover the round shape of the eyeball, whereas those cells in the periphery have a radial orientation and corresponding radial elongation, the extent of which increases with aging and matches with axial elongation of the eyeball. Conclusions: These results suggest that the fluid RPE morphology reflects various growth rates of underlying eyeball, and RPE cells could be classified into four regional classes (near the optic disc, central, equatorial, and peripheral) according to their morphometric features.

INTRAOCULAR AND INTEROCULAR DIFFERENCES IN PARAFOVEAL VASCULAR DENSITY IN DIABETIC PATIENTS WITHOUT DIABETIC RETINOPATHY.

PURPOSE: To evaluate the associations among optical coherence tomography angiography-measured vascular density (VD), intraocular and interocular VD differences, and clinical factors in diabetic patients without diabetic retinopathy. METHODS: We retrospectively reviewed 94 Type 2 diabetic patients without diabetic retinopathy who had undergone optical coherence tomography angiography. Vascular density and vessel skeleton density were measured in a 3-mm central zone in the total capillary plexus, superficial capillary plexus, deep capillary plexus (DCP), and choriocapillaris layers. Intraocular VD difference was determined between the superior and inferior zones, while interocular VD difference was determined between both eyes of the patient. Associations between optical coherence tomography angiography parameters and clinical factors were evaluated. RESULTS: Vascular density and intraocular and interocular VD differences were significantly associated with signal strength of the image, which was related with age and lens opacity. In multivariate analysis, diabetes duration was negatively associated with skeleton density in total capillary plexus and superficial capillary plexus layers, and positively associated with intraocular VD difference in superficial capillary plexus layer. Estimated glomerular filtration rate was negatively associated with intraocular skeleton density difference in total capillary plexus layer, interocular VD, and skeleton density differences in total capillary plexus layer. CONCLUSION: Intraocular and interocular VD difference may be an easy and sensitive way to detect subtle early microvascular changes in diabetic patients.