Crosstalk between endoplasmic reticulum stress and mitochondrial homeostasis: A new perspective on ophthalmic disease...

Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are hallmarks of many ophthalmic diseases; however, they have traditionally been examined as isolated pathological processes. Recent evidence indicates that these organelles are inextricably coupled through mitochondria-endoplasmic reticulum contact sites, also known as mitochondria-associated membranes (MAMs), which coordinate Ca²⁺ signaling, lipid transfer, mitochondrial dynamics, redox balance, and cell death decisions. Consequently, dysregulated ER-mitochondria communication has emerged as a key vulnerability that links the cellular stress responses among diverse ocular tissues, including lens epithelial cells, retinal ganglion cells, the retinal pigment epithelium, and corneal endothelial cells. In this review, we summarize the recent advances involving the molecular architecture and regulatory function of ER-mitochondria crosstalk. We focus on how the unfolded protein response signaling, pathological MAM remodeling, Ca²⁺ dysregulation, and disrupted mitochondrial quality control collectively drive disease progression. By integrating evidence from cataract, glaucoma, diabetic retinopathy, age-related macular degeneration, and Fuchs endothelial corneal dystrophy, we reveal that these disorders are not driven by a uniform mechanism of organelle failure, but rather by the dominance of pathological nodes along the ER-mitochondria axis. We propose that ophthalmic diseases should be stratified based on these distinct failure nodes, which provides a mechanistic framework for developing therapeutics. Within this context, interventions targeting maladaptive ER stress, MAM destabilization, bioenergetic failure, or defective mitophagy should be considered complementary and context-dependent strategies. By reframing ophthalmic disorders as diseases of inter-organelle stress integration, this review positions the ER-mitochondria axis as a modifiable upstream determinant of ocular cell fate, which provides a foundation for stage-specific precision therapies.