Photic Sneeze Reflex via Corneal TRP Activation: Trigeminal Convergence Mechanism and Clinical Implications

DescriptionThis paper presents a novel, unified model for the Photic Sneeze Reflex (PSR), integrating molecular, neuroanatomical, and clinical evidence into a single, testable pathway. Unlike previous explanations—such as parasympathetic overflow or non-specific optic–trigeminal summation—this model proposes TRP channel activation in corneal and upper nasal ophthalmic (V1) fibers as the primary trigger, and proposes a trigeminal-centered reflex arc that unites sneezing and tearing as parallel protective mechanisms. The work introduces new clinical evidence from gelatinous corneal dystrophy (GCD) as a natural experiment, demonstrating heightened PSR prevalence and modulation after corneal transplantation. This association, observed in members of an extended family offers compelling support for the proposed corneal–nasal bridge via the nasociliary nerve. The manuscript is organized to first review sneezing mechanisms and relevant literature, then detail the proposed pathway, TRP channel physiology, and functional cross-reflex logic. It closes with predictions, clinical implications, and historical observations from ophthalmic practice. Key contributions include: First mechanistic model to link corneal TRP activation to PSR. Novel use of GCD as clinical evidence for corneal involvement. Unification of sneezing and tearing reflexes through shared trigeminal integration. Predictions for experimental validation and therapeutic exploration. This research reframes PSR as an adaptive, field-protective response rather than a benign oddity, with relevance for ophthalmology, neurology, and sensory physiology. Dr. Ghassan Ahmed Mubasher MohamedsalihNeuro-Ophthalmologist, Hamad Medical Corporation, QatarEmail: [email protected]: https://orcid.org/0009-0000-7926-3150