Major Arterial Circle of the Iris

Description

Encircling the pupillary margin within the iris stroma, the major arterial circle of the iris forms a circumferential anastomosis near the iris root, just anterior to the ciliary body and posterior to the corneoscleral limbus. Feeding arterioles course radially from the ciliary region toward the pupil, where they interconnect to complete the ring, while the cornea and sclera frame the anterior segment and the crystalline lens sits immediately posterior to the pupil. Posteriorly, the optic nerve exits the globe at the optic disc, with the retinal vasculature spread across the inner surface of the posterior pole. Attention to the major arterial circle matters because it is the principal arterial arcade supplying the iris, and it explains the sectoral perfusion patterns seen in anterior segment ischemia, traumatic iridodialysis, and postoperative inflammation. During cataract surgery, glaucoma filtering procedures, or iridectomy, disruption of iris or ciliary body vessels can alter perfusion of this anastomotic ring, predisposing to hyphema and irregular pupillary reactions; the relationship of the circle to the iris root is a surgical landmark. A short, clear ring. It also helps clinicians understand why neovascularization of the iris (rubeosis iridis) often tracks along preexisting vascular routes in eyes with proliferative diabetic retinopathy or central retinal vein occlusion, even though the initiating ischemia is posterior. Ophthalmology and optometry educators can place this illustration alongside gonioscopy and anterior segment OCT discussions to teach iris vascular anatomy, then link it to operative complications and uveitic patterns of hyperemia. Medical publishers will find it well suited for atlas plates on uveal circulation, chapters on ocular trauma, and patient-facing explanations of hyphema and iris neovascularization. Anatomical accuracy verified by SciePro's Medical Advisory Board.