Brolucizumab in Neovascular Age-Related Macular Degeneration and Diabetic Macular Edema: Ophthalmology and Diabetology Treatment Aspects.

Anti-vascular endothelial growth factor (anti-VEGF) therapies have become the standard of care in the treatment of neovascular age-related macular degeneration (nAMD) and diabetic macular edema (DME), resulting in a remarkable decrease in disease-related vision loss. However, the need for regular injections places a significant burden on patients, caregivers, and the healthcare system and improvements in vision may not be maintained long term. As a result of its drying potency and duration of action, brolucizumab, an intravitreal anti-VEGF therapy approved for the treatment of nAMD and DME, could decrease injection frequency for patients and provide an efficacious treatment; however, balancing its benefits and risks can be challenging. There have been reports of intraocular inflammation (IOI) in patients treated with brolucizumab, which, if left untreated, may result in severe vision loss. Recent evidence, however, indicates that early recognition of IOI and prompt and aggressive systemic corticosteroid treatment in response to posterior segment involvement can lead to favorable outcomes in these relatively rare but severe cases. A series of consensus meetings were conducted in 2022 between Swiss medical retina experts and diabetologists, discussing the current data for brolucizumab and exploring various challenges to its use, including the associated risk of IOI. The outcome is a collation of practical insights and guidance for ophthalmologists on the use of brolucizumab in patients with nAMD and DME, including patient selection and assessment, treatment regimen and monitoring, and the recognition and management of adverse events.

The Predictive Role of Thyroid Hormone Levels for Early Diabetic Retinal Changes in Experimental Rat and Human Diabetes.

Purpose: In diabetic subjects, early visual functional alterations such as color vision deficiencies (CVDs) are known to precede clinically apparent diabetic retinopathy. Prominent photoreceptor outer segment degeneration and an increase in the number of retinal dual cones (co-expressing S- and M-opsins simultaneously) have been described in diabetic rat models, suggesting a connection with the development of CVDs. As cone opsin expression is controlled by thyroid hormones, we investigated the diabetic retina in association with thyroid hormone alterations. Methods: In rat models of type 1 and 2 diabetes, dual cones were labeled by immunohistochemistry, and their numbers were analyzed in relation to free triiodothyronine (fT3) and free thyroxine (fT4) levels. Quantification of dual cones was also performed in human postmortem retinas. Additionally, a cross-sectional case-control study was performed where thyroid hormone levels were measured and color vision was assessed with Lanthony desaturated D15 discs. Results: A higher number of dual cones was detectable in diabetic rats, correlating with fT4 levels. Dual cones were also present in postmortem human retinas, with higher numbers in the three diabetic retinas. As expected, age was strongly associated with CVDs in human patients, and the presence of diabetes also increased the risk. However, the current study failed to detect any effect of thyroid hormones on the development of CVDs. Conclusions: Our results point toward the involvement of thyroid homeostasis in the opsin expression changes in diabetic rats and human samples. The evaluation of the possible clinical consequences warrants further research.

Detailed Evaluation of Possible Ganglion Cell Loss in the Retina of Zucker Diabetic Fatty (ZDF) Rats.

A thinning of the inner retina is one of the earliest potential markers of neuroretinal damage in diabetic subjects. The histological background is uncertain; retinal ganglion cell (RGC) loss and changes in the structure or thickness of the inner plexiform layer (IPL) have been suspected. Studies conducted on animal models on RGC pathology gave contradictory results. Hereby we present RGC numbers, distribution patterns and IPL thickness from Zucker Diabetic Fatty (ZDF) rats. After labelling RGCs on retinal whole mounts, isodensity maps were constructed, RGC numbers and distribution patterns analysed using a custom-built algorithm, enabling point-by-point comparison. There was no change in staining characteristics of the antibodies and no significant difference in average RGC densities was found compared to controls. The distribution patterns were also comparable and no significant difference was found in IPL thickness and stratification or in the number of apoptotic cells in the ganglion cell layer (GCL). Our results provide a detailed evaluation of the inner retina and exclude major RGC loss in ZDF rats and suggest that other factors could serve as a potential explanation for inner retinal thinning in clinical studies. Our custom-built method could be adopted for the assessment of other animal or human retinas.

The effect of ranibizumab and aflibercept treatment on the prevalence of outer retinal tubulation and its influence on retreatment in neovascular age-related macular degeneration.

BACKGROUND: We aimed to analyze the differences in the prevalence of outer retinal tubulation (ORT) in neovascular age-related macular degeneration (AMD) treated with anti-vascular endothelial growth factor (anti-VEGF) agents, either aflibercept or ranibizumab. Our further aim was to examine the changes in the frequency of injections of ranibizumab before and after ORT appearance. METHODS: Two hundred thirty six eyes of 230 patients were included in the study (184 eyes treated with ranibizumab by pro re nata regimen (PRN), 52 eyes with aflibercept bimonthly) and followed for 6-24 months. Using optical coherence tomography (OCT), the first appearance of ORT was documented, and fixed time point evaluations were also made every six months to determine the existence of ORT. The number of injections, the presence or absence of subretinal hyperreflective material (SHRM) at treatment initiation and visual acuity were also noted. RESULTS: The survival analysis with Cox proportional hazard model showed no significant difference between the ranibizumab and aflibercept groups in relation to the development of ORT (p = 0.79, hazard ratio 0.92). In the PRN treated ranibizumab group the number of injections showed significant decrease after ORT development (p = 0.004). When SHRM was present at treatment initiation the chance of developing ORT was 2.75 and 11.14 times higher in the ranibizumab and aflibercept groups, respectively. CONCLUSIONS: The prevalence of ORT increased over time independently from the chosen anti-VEGF drug. Our results suggest that upon the appearance of ORT a decrease in retreatments can be expected.

Investigating the Fractal Dimension of the Foveal Microvasculature in Relation to the Morphology of the Foveal Avascular Zone and to the Macular Circulation in Patients With Type 2 Diabetes Mellitus.

In this study, we examined the relationship between the fractal dimension (FD), the morphology of the foveal avascular zone (FAZ) and the macular circulation in healthy controls and patients with type 2 diabetes mellitus (T2DM) with and with no diabetic retinopathy (DR). Cross-sectional data of 47 subjects were analyzed from a 5-year longitudinal study using a multimodal optical imaging approach. Healthy eyes from nondiabetic volunteers (n = 12) were selected as controls. Eyes from patients with T2DM were selected and divided into two groups: diabetic subjects with mild DR (MDR group, n = 15) and subjects with DM but without DR (DM group, n = 20). Our results demonstrated a higher FD in the healthy group (mean, 1.42 ± 0.03) than in the DM and MDR groups (1.39 ± 0.02 and 1.35 ± 0.03, respectively). Also, a bigger perimeter, area, and roundness of the FAZ were found in MDR eyes. A significant difference in area and perimeter (p ≤ 0.005) was observed for the MDR group supporting the enlargement of the FAZ due to diabetic complications in the eye. A moderate positive correlation (p = 0.014, R2 = 43.8%) between the FD and blood flow rate (BFR) was only found in the healthy control group. The BFR calculations revealed the lowest values in the MDR group (0.98 ± 0.27 µl/s vs. 1.36 ± 0.86 µl/s and 1.36 ± 0.57 µl/sec in the MDR, DM, and healthy groups, respectively, p = 0.2). Our study suggests that the FD of the foveal vessel arborization could provide useful information to identify early morphological changes in the retina of patients with T2DM. Our results also indicate that the enlargement and asymmetry of the FAZ might be related to a lower BFR because of the DR onset and progression. Interestingly, due to the lack of FAZ symmetry observed in the DM and MDR eyes, it appears that the distribution of flow within the retinal vessels loses complexity as the vascular structures distributing the flow are not well described by fractal branching. Further research could determine how our approach may be used to aid the diagnosis of retinal neurodegeneration and vascular impairment at the early stage of DR.

Histological Evaluation of Diabetic Neurodegeneration in the Retina of Zucker Diabetic Fatty (ZDF) Rats.

In diabetes, retinal dysfunctions exist prior to clinically detectable vasculopathy, however the pathology behind these functional deficits is still not fully established. Previously, our group published a detailed study on the retinal histopathology of type 1 diabetic (T1D) rat model, where specific alterations were detected. Although the majority of human diabetic patients have type 2 diabetes (T2D), similar studies on T2D models are practically absent. To fill this gap, we examined Zucker Diabetic Fatty (ZDF) rats - a model for T2D - by immunohistochemistry at the age of 32 weeks. Glial reactivity was observed in all diabetic specimens, accompanied by an increase in the number of microglia cells. Prominent outer segment degeneration was detectable with changes in cone opsin expression pattern, without a decrease in the number of labelled elements. The immunoreactivity of AII amacrine cells was markedly decreased and changes were detectable in the number and staining of some other amacrine cell subtypes, while most other cells examined did not show any major alterations. Overall, the retinal histology of ZDF rats shows a surprising similarity to T1D rats indicating that despite the different evolution of the disease, the neuroretinal cells affected are the same in both subtypes of diabetes.

Improving image segmentation performance and quantitative analysis via a computer-aided grading methodology for optical coherence tomography retinal image analysis.

We demonstrate quantitative analysis and error correction of optical coherence tomography (OCT) retinal images by using a custom-built, computer-aided grading methodology. A total of 60 Stratus OCT (Carl Zeiss Meditec, Dublin, California) B-scans collected from ten normal healthy eyes are analyzed by two independent graders. The average retinal thickness per macular region is compared with the automated Stratus OCT results. Intergrader and intragrader reproducibility is calculated by Bland-Altman plots of the mean difference between both gradings and by Pearson correlation coefficients. In addition, the correlation between Stratus OCT and our methodology-derived thickness is also presented. The mean thickness difference between Stratus OCT and our methodology is 6.53 microm and 26.71 microm when using the inner segment/outer segment (IS/OS) junction and outer segment/retinal pigment epithelium (OS/RPE) junction as the outer retinal border, respectively. Overall, the median of the thickness differences as a percentage of the mean thickness is less than 1% and 2% for the intragrader and intergrader reproducibility test, respectively. The measurement accuracy range of the OCT retinal image analysis (OCTRIMA) algorithm is between 0.27 and 1.47 microm and 0.6 and 1.76 microm for the intragrader and intergrader reproducibility tests, respectively. Pearson correlation coefficients demonstrate R(2)>0.98 for all Early Treatment Diabetic Retinopathy Study (ETDRS) regions. Our methodology facilitates a more robust and localized quantification of the retinal structure in normal healthy controls and patients with clinically significant intraretinal features.

Truncation of retinoschisin protein associated with a novel splice site mutation in the RS1 gene.

PURPOSE: To present the ocular findings of a Hungarian family with X-linked juvenile retinoschisis (XLRS) and to reveal a novel putative splice mutation leading to serious truncation of retinoschisin (RS1) protein. Our genetic results were compared to a mouse model of XLRS. METHODS: Complete ophthalmic examinations were performed on five members (two male patients, two female carriers, and one healthy fraternal male twin) of the family. The examinations included optical coherence tomography (OCT) and full-field and multifocal electroretinography (mfERG). OCT and ERG results were compared to the normative database of our laboratory. All exons and the flanking intronic regions of the RS1 gene were amplified by polymerase chain reaction and directly sequenced in all family members and in 50 male controls. RESULTS: Typical microcystic foveal changes were found on fundoscopy and OCT in two male patients. Large foveal and smaller perifoveal cysts were detected by OCT in the inner nuclear layer and another deeper retinal cleavage in the photoreceptor layer. The standard combined b-wave amplitudes and b/a amplitude ratios of full-field ERGs of the male patients were decreased compared with controls, but the typical "negative-type" ERG was not observed. The amplitudes of mfERGs were reduced in all rings but mainly in the central part of the examined retina. Implicit times were delayed across almost the whole testing field. Female carriers and the healthy fraternal twin brother were without any symptoms and had normal clinical examination results, but the implicit times of female carriers were delayed in all rings. DNA sequence analyses revealed a novel putative splice mutation (c.78+1G>C) in the splice donor site of intron 2 in RS1 of two male patients and two female carriers. Mutations were absent in the 50 control samples. CONCLUSIONS: Male patients exhibited typical bilateral foveal retinoschisis in two retinal layers and characteristic ERG changes. The inheritance of the novel putative splice mutation (c.78+1G>C) followed the classic inheritance of an X-linked recessive disease in two male patients and two female obligate carriers. There are two possible ways the c.78+1G>C splice site mutation may lead to frameshift and introduce a premature termination codon at the beginning of exon 3: after activation of the next cryptic splice site by a 10 bp insertion or after exon skipping by a 26 bp deletion. The splice site mutation in the second intron of RS1 identified in these XLRS patients is practically identical to the N-ethyl-N-nitrosourea (ENU) induced splice site mutation in the mouse model of XLRS described by the Tennessee Mouse Genome Consortium. The genetic findings of the mutant mouse model confirm and support our human results.

Correlation of clinical and genetic findings in Hungarian patients with Stargardt disease.

PURPOSE: Autosomal recessive Stargardt disease (arSTGD) presents with substantial clinical and genetic heterogeneity. This study was conducted to correlate foveolar thickness (FT) and total macular volume (TMV), measured by optical coherence tomography (OCT), with other clinical characteristics and with specific genetic variation in Hungarian patients with arSTGD. METHODS: After a standard ophthalmic workup, both eyes of 35 patients with STGD from Hungary and of 25 age-matched healthy control subjects were tested with OCT. FT and TMV were measured automatically with the OCT mapping software in the nine Early Treatment Diabetic Retinopathy Study areas of 3500 microm in diameter. All patients were screened for mutations by a combination of the ABCR400 microarray and direct sequencing. RESULTS: The patients with STGD presented with markedly thinned retina in the foveola and decreased macular volume, 72 microm and 1.69 mm3, respectively, compared with 169 microm and 2.48 mm3 in the normal subjects, respectively. Statistically significant correlation was observed between visual acuity (VA) and TMV and between VA and FT. Disease-associated mutations were detected in 23 (65.7%) of 35 patients, including 48.5% with both alleles and 17.2% with one allele. The most frequent ABCA4 alleles in Hungarian patients with STGD were L541P/A1038V (in 28% of all patients), G1961E (20%) and IVS40+5G-->A (17%). Specific genotypes correlated with some phenotypic features and allowed for predictions of the disease progression. CONCLUSIONS: Hungarian patients with STGD presented with extensive foveolar thinning and macular volume loss. Genetic analysis detected several ABCA4 alleles at high frequency in the cohort of patients, suggesting founder effect(s). Unusually homogeneous distribution of disease-associated mutations aided genotype-phenotype correlation analyses in this population.