Vessel density changes in choroid, chorio-capillaries, deep and superficial retinal plexues on OCTA in normal ageing and various stages of age-related macular degeneration

Role of IP3R2-Mediated mitochondrial calcium homeostasis in early hypoxic stress injury of retinal pigment epithelial cells

OBJECTIVE

To investigate the regulatory role of IP3R2 on mitochondrial function in retinal pigment epithelial cells during the early stage of hypoxic stress preceding apoptosis.

METHODS

ARPE-19 cell line was cultured in 1 % oxygen to establish an in vitro hypoxic model. The presence of hypoxia and absence of significant apoptosis in RPE cells were confirmed through hypoxia-inducible factor HIF-1α expression and apoptosis assays respectively. Mitochondrial function was evaluated using an ATP assay kit and flow cytometry. Immunoblotting was conducted to ascertain the expression levels of mitochondrial dynamics proteins (MFN2, DRP1, TOMM20) and mitochondrial calcium-related proteins (IP3R1, IP3R2, IP3R3, VDAC1). Mitochondrial morphology was observed using confocal microscopy. The impact of small interfering RNA (siRNA)-mediated IP3R2 knockdown on apoptosis and mitochondrial function was assessed in RPE cells.

RESULTS

Under hypoxic stress before the onset of apoptosis in RPE cells, mitochondrial dysfunction and significant increase in mitochondrial calcium flux were observed, accompanied by a notable upregulation of IP3R2 expression under hypoxia. Knockdown of IP3R2 during the pre-apoptotic stage further impaired RPE function under hypoxia.

CONCLUSION

IP3R2-mediated mitochondrial calcium overload is crucial for maintaining RPE function and mitochondrial homeostasis during the pre-apoptotic stage triggered by hypoxic stress.

Neuroprotection beyond intraocular pressure: game changer or quiet addiction

The topic of neuroprotection in glaucoma and age-related macular degeneration (AMD) is well disseminated in the literature. However, the problem is providing ophthalmologists with clear, evidence-based messages to draw on. This review examines the landscape of neuroprotective therapies for glaucoma and AMD. While promising neuroprotective agents, such as citicoline and nicotinamide, have been explored for their potential to mitigate neurodegeneration in glaucoma, robust clinical evidence validating their efficacy remains limited and there is a need for further large-scale, long-term studies to substantiate the neuroprotective effects of these agents. Maintaining low intraocular pressure plays a vital role in preventing neuronal death in glaucoma. AMD has traditionally been considered a disease affecting the outer retinal layers; however, growing evidence suggests that the inner layers are also involved. Neuroprotection is an emerging area of research, with strategies focusing on alleviating oxidative stress, inflammation and apoptosis. A reassessment of clinical endpoints and methodologies in neuroprotection research is critical to better evaluate the efficacy of these therapies in glaucoma and AMD.

Non-Neovascular Age-Related Macular Degeneration Assessment: Focus on Optical Coherence Tomography Biomarkers

The imagistic evaluation of non-neovascular age-related macular degeneration (AMD) is crucial for diagnosis, monitoring progression, and guiding management of the disease. Dry AMD, characterized primarily by the presence of drusen and retinal pigment epithelium atrophy, requires detailed visualization of the retinal structure to assess its severity and progression. Several imaging modalities are pivotal in the evaluation of non-neovascular AMD, including optical coherence tomography, fundus autofluorescence, or color fundus photography. In the context of emerging therapies for geographic atrophy, like pegcetacoplan, it is critical to establish the baseline status of the disease, monitor the development and expansion of geographic atrophy, and to evaluate the retina's response to potential treatments in clinical trials. The present review, while initially providing a comprehensive description of the pathophysiology involved in AMD, aims to offer an overview of the imaging modalities employed in the evaluation of non-neovascular AMD. Special emphasis is placed on the assessment of progression biomarkers as discerned through optical coherence tomography. As the landscape of AMD treatment continues to evolve, advanced imaging techniques will remain at the forefront, enabling clinicians to offer the most effective and tailored treatments to their patients.