An Experimental Model of Neuro-Immune Interactions in the Eye: Corneal Sensory Nerves and Resident Dendritic Cells.

The cornea is an avascular connective tissue that is crucial, not only as the primary barrier of the eye but also as a proper transparent refractive structure. Corneal transparency is necessary for vision and is the result of several factors, including its highly organized structure, the physiology of its few cellular components, the lack of myelinated nerves (although it is extremely innervated), the tightly controlled hydration state, and the absence of blood and lymphatic vessels in healthy conditions, among others. The avascular, immune-privileged tissue of the cornea is an ideal model to study the interactions between its well-characterized and dense sensory nerves (easily accessible for both focal electrophysiological recording and morphological studies) and the low number of resident immune cell types, distinguished from those cells migrating from blood vessels. This paper presents an overview of the corneal structure and innervation, the resident dendritic cell (DC) subpopulations present in the cornea, their distribution in relation to corneal nerves, and their role in ocular inflammatory diseases. A mouse model in which sensory axons are constitutively labeled with tdTomato and DCs with green fluorescent protein (GFP) allows further analysis of the neuro-immune crosstalk under inflammatory and steady-state conditions of the eye.

Differential diagnosis of acute ocular pain: Teleophthalmology during COVID-19 pandemic - A perspective.

Ocular pain is a common complaint which forces the patient to seek immediate medical attention. It is the primeval first response of the body to any severe condition of the eye such as trauma, infections and inflammation. The pain can be due to conditions directly affecting the eye and ocular adnexa; or indirect which would manifest as referred pain from other organ structures such as the central nervous system. Paradoxically, there are several minor and non-sight threatening conditions, which also leads to ocular pain and does not merit urgent hospital visits. In this perspective, we intend to provide guidelines to the practising ophthalmologist for teleconsultation when a patient complains of pain with focus on how to differentiate the various diagnoses that can be managed over teleconsultation and those requiring emergency care in the clinic. These guidelines can decrease unnecessary hospital visits, which is the need of the hour in the pandemic era and also beyond. Patients who are under quarantine and those who are unable to travel would be benefitted, and at the same time, the burden of increased patient load in busy hospital systems can be reduced.