A glimpse at the aging eye

Clinical characteristics of chronic central serous chorioretinopathy patients with insufficient response to reduced-settings photodynamic therapy

Purpose

To identify characteristics of Caucasian chronic central serous chorioretinopathy (cCSC) patients without a complete resolution of subretinal fluid (SRF) after reduced-settings photodynamic therapy (PDT), or with a recurrence of SRF after PDT.

Methods

Chronic CSC patients treated with reduced-settings PDT were divided into a successful PDT group and unsuccessful PDT group. Patients in the successful PDT group did not have any subretinal fluid (SRF) during follow-up after PDT, whereas the unsuccessful PDT group was categorized based on either persistence or recurrence of SRF after PDT treatment. Data on age, sex, best-corrected visual acuity (BCVA), PDT spot size, characteristics on fluorescein angiography (FA), indocyanine green angiography (ICGA), and optical coherence tomography (OCT) were obtained.

Results

Twenty-six patients in the successful PDT group (20 males, 6 females) had a mean age of 51 years (range, 25–78). In the unsuccessful PDT group, 20 males with a mean age of 60 years (range, 34–78) were included. At last visit before PDT, age, percentage of males, and percentage of patients with diffuse leakage > 1 optic disc diameter on FA were higher in the unsuccessful PDT group (p = 0.010, p = 0.029, and p = 0.008, respectively). At last visit before PDT, BCVA and the percentage of patients with intense hyperfluorescence on ICGA were lower in the unsuccessful group (p = 0.017 and p = 0.004, respectively). Patients with intense hyperfluorescence on ICGA were more likely (95% CI 1.3–333 times) to have a successful outcome (p = 0.045). A decrease in SFCT at final visit was observed in both groups (− 111 μm and p = 0.013, and − 141 μm and p = 0.007, respectively). BCVA only improved at final visit in the successful PDT group (5 Early Treatment of Diabetic Retinopathy Study letters, p < 0.001).

Conclusions

Chronic CSC patients with recurrent or persistent SRF after PDT are characterized by a higher percentage of males, more patients with diffuse leakage on FA, more patients without intense hyperfluorescence on ICGA, higher age, and lower pre-PDT and long-term BCVA than in the successful PDT group. A reduction in SFCT after PDT does not necessarily lead to complete resolution of SRF, while a resolution of SRF appears to be required to lead to a significant BCVA improvement in cCSC.

Proteomic analysis of the human retina reveals region-specific susceptibilities to metabolic- and oxidative stress-related diseases

Differences in regional protein expression within the human retina may explain molecular predisposition of specific regions to ophthalmic diseases like age-related macular degeneration, cystoid macular edema, retinitis pigmentosa, and diabetic retinopathy. To quantify protein levels in the human retina and identify patterns of differentially-expressed proteins, we collected foveomacular, juxta-macular, and peripheral retina punch biopsies from healthy donor eyes and analyzed protein content by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Protein expression was analyzed with 1-way ANOVA, gene ontology, pathway representation, and network analysis. We identified a mean of 1,974 proteins in the foveomacular retina, 1,999 in the juxta-macular retina, and 1,779 in the peripheral retina. Six hundred ninety-seven differentially-expressed proteins included those unique to and abundant in each anatomic region. Proteins with higher expression in each region include: heat-shock protein 90-alpha (HSP90AA1), and pyruvate kinase (PKM) in the foveomacular retina; vimentin (VIM) and fructose-bisphosphate aldolase C (ALDOC); and guanine nucleotide-binding protein subunit beta-1 (GNB1) and guanine nucleotide-binding protein subunit alpha-1 (GNAT1) in the peripheral retina. Pathway analysis identified downstream mediators of the integrin signaling pathway to be highly represented in the foveomacular region (P = 6.48 e-06). Metabolic pathways were differentially expressed among all retinal regions. Gene ontology analysis showed that proteins related to antioxidant activity were higher in the juxta-macular and the peripheral retina, but present in lower amounts in the foveomacular retina. Our proteomic analysis suggests that certain retinal regions are susceptible to different forms of metabolic and oxidative stress. The findings give mechanistic insight into retina function, reveal important molecular processes, and prioritize new pathways for therapeutic targeting.

Alterations in glutamatergic signaling contribute to the decline of circadian photoentrainment in aged mice

Robust physiological circadian rhythms form an integral part of well-being. The aging process has been found to negatively impact systems that drive circadian physiology, typically manifesting as symptoms associated with abnormal/disrupted sleeping patterns. Here, we investigated the age-related decline in light-driven circadian entrainment in male C57BL/6J mice. We compared light-driven resetting of circadian behavioral activity in young (1-2 months) and old (14-18 months) mice and explored alterations in the glutamatergic pathway at the level of the circadian pacemaker, the suprachiasmatic nucleus (SCN). Aged animals showed a significant reduction in sensitivity to behavioral phase resetting by light. We show that this change was through alterations in N-Methyl-D-aspartate (NMDA) signaling at the SCN, where NMDA, a glutamatergic agonist, was less potent in inducing clock resetting. Finally, we show that this shift in NMDA sensitivity was through the reduced SCN expression of this receptor's NR2B subunit. Only in young animals did an NR2B antagonist attenuate behavioral resetting. These results can help target treatments that aim to improve both physiological and behavioral circadian entrainment in aged populations.

Epigenetic Treatment of Neurodegenerative Ophthalmic Disorders: An Eye Toward the Future

Eye disease is one of the primary medical conditions that requires attention and therapeutic intervention in ageing populations worldwide. Further, the global burden of diabetes and obesity, along with heart disease, all lead to secondary manifestations of ophthalmic distress. Therefore, there is increased interest in developing innovative new approaches that target various mechanisms and sequelae driving conditions that result in adverse vision. The research challenge is even greater given that the terrain of eye diseases is difficult to landscape into a single therapeutic theme. This report addresses the burden of eye disease due to mitochondrial dysfunction, including antioxidant, autophagic, epigenetic, mitophagic, and other cellular processes that modulate the biomedical end result. In this light, we single out lipoic acid as a potent known natural activator of these pathways, along with alternative and potentially more effective conjugates, which together harness the necessary potency, specificity, and biodistribution parameters required for improved therapeutic outcomes.

NAMPT-Mediated NAD(+) Biosynthesis Is Essential for Vision In Mice

Photoreceptor death is the endpoint of many blinding diseases. Identifying unifying pathogenic mechanisms in these diseases may offer global approaches for facilitating photoreceptor survival. We found that rod or cone photoreceptor-specific deletion of nicotinamide phosphoribosyltransferase (Nampt), the rate-limiting enzyme in the major NAD(+) biosynthetic pathway beginning with nicotinamide, caused retinal degeneration. In both cases, we could rescue vision with nicotinamide mononucleotide (NMN). Significantly, retinal NAD(+) deficiency was an early feature of multiple mouse models of retinal dysfunction, including light-induced degeneration, streptozotocin-induced diabetic retinopathy, and age-associated dysfunction. Mechanistically, NAD(+) deficiency caused metabolic dysfunction and consequent photoreceptor death. We further demonstrate that the NAD(+)-dependent mitochondrial deacylases SIRT3 and SIRT5 play important roles in retinal homeostasis and that NAD(+) deficiency causes SIRT3 dysfunction. These findings demonstrate that NAD(+) biosynthesis is essential for vision, provide a foundation for future work to further clarify the mechanisms involved, and identify a unifying therapeutic target for diverse blinding diseases.