Rhegmatogenous Retinal Detachment — Diagnosis & Risk Factors

Overview: What "Rhegmatogenous" Means

A rhegmatogenous retinal detachment (RRD) develops when a full-thickness break in the neurosensory retina lets liquefied vitreous pass through and collect in the potential space between the retina and the retinal pigment epithelium (RPE). Once fluid separates the two layers, the photoreceptors lose their metabolic support from the RPE and stop functioning. That dependence is why RRD is treated as urgent. On fundus exam the detached retina stands out as an elevated, wrinkled sheet, out of the plane of focus against the surrounding attached retina, with pale billowing tissue hanging over the red-orange choroid beneath it.

RRD is one of three detachment mechanisms. The other two, tractional and exudative detachment, involve no actual break: tractional detachment comes from membrane contraction pulling the retina away, and exudative detachment comes from fluid leaking out of a sick RPE or choroid. The Greek root rhegma means break, and that break is what defines RRD and dictates its treatment. Surgical repair is built around finding and sealing the break itself, not simply draining the subretinal fluid.

Clinical Presentation

The classic presenting triad is photopsia, floaters, and progressive peripheral field loss. Flashes come from vitreoretinal traction, new floaters from vitreous hemorrhage or pigment released through the break, and the field defect from the detachment itself spreading like a curtain or shadow. Patients typically describe it starting at the edge of vision and advancing toward the center as more retina comes away.

These symptoms often start with an acute posterior vitreous detachment (PVD), the age-related separation of the vitreous gel from the retina. A single new ring-shaped floater with flashes is the classic acute-PVD presentation, and it should prompt a dilated peripheral exam on its own: the same traction that causes a PVD can tear the retina wherever the two are still firmly stuck together. That ring-shaped floater is a Weiss ring, glial tissue that was attached to the optic disc margin and gets torn free along with the posterior hyaloid face during separation. A Weiss ring by itself only confirms PVD, not a break, so it has to be distinguished on exam from the more ominous V-shaped, disc-attached membrane of an actual detachment (see Imaging below).

Risk Factors: Lattice Degeneration and Horseshoe Tears

Lattice degeneration is peripheral retinal thinning marked by a criss-crossing pattern of sclerotic vessels, overlying vitreous liquefaction, and unusually strong vitreoretinal adhesion right at its margins. A thin retina tethered firmly to vitreous that's already mobile and liquefied is a setup for a tear whenever that vitreous shifts, which makes lattice degeneration one of the major risk factors for retinal breaks and the RRD that can follow.

When traction does tear the retina during an acute PVD, the result is often a horseshoe, or flap, tear: a full-thickness break with one edge still pulled open by ongoing vitreous traction on the flap. That traction doesn't resolve on its own, so horseshoe tears carry a standing risk of progressing to RRD and get treated more urgently than a simple round hole.

A retinal hole, by contrast, is round and sharply demarcated, often found incidentally in the far periphery on a dilated exam, with no flap under active traction. Symptomatic or otherwise high-risk holes and tears get laser photocoagulation or cryotherapy, which walls off the break with a chorioretinal adhesion and keeps fluid from tracking underneath it before it ever becomes a detachment.

Lattice degeneration isn't the only major risk factor. Axial myopia carries the strongest refractive risk: eyes with more than about 6 diopters of myopia have up to roughly 39 times the RRD incidence of non-myopic eyes, because progressive axial elongation thins the peripheral retina and liquefies the vitreous earlier than it would in an emmetropic eye. Pseudophakic and aphakic eyes carry their own two- to four-fold increase in risk once cataract surgery disrupts normal vitreous support. Myopia, lattice degeneration, and prior intraocular surgery all act on both eyes at once, so a patient who has already had one RRD carries a real risk of a fellow-eye detachment and should be examined and counseled accordingly.

Exam Findings: Shafer Sign and Retinal Holes

Shafer sign is the clinical name for pigmented cells that look like tobacco dust, dispersed retinal pigment epithelial cells released through a retinal break and seen on slit-lamp exam of the anterior vitreous. It carries a high positive predictive value for an associated retinal tear or RRD, well above a Weiss ring, white cells, or diffuse non-pigmented vitreous hemorrhage as an indicator of a break. In a patient presenting with new photopsia and floaters, Shafer sign at the slit lamp is the single finding most predictive of an underlying break and should trigger an immediate, careful search of the periphery for the tear causing it.

Imaging and Localization

When a dense vitreous hemorrhage or cataract blocks a clear fundus view, B-scan ocular ultrasonography is the modality of choice. It penetrates opaque media, picks up the mobile, highly reflective membrane that marks a detached retina, and can assess macular involvement when direct visualization is impossible. On B-scan, RRD classically shows as a V-shaped, highly reflective membrane converging at the optic disc, producing the funnel configuration seen in more advanced or total detachments. The retina stays anchored at both the disc and the ora serrata, so that convergence at the disc is what separates an RRD membrane from a PVD membrane, which never attaches there and never produces the same funnel.

Once a break is suspected, Lincoff's rules predict its likely location from the shape of the detachment before formal scleral depression even begins. For a superior, non-total, bullous detachment, the primary break usually sits within about 1.5 clock hours of the detachment's highest point, a rule of thumb that narrows the peripheral search and speeds up intraoperative localization.

Classification: Macula-On vs. Macula-Off, Acute vs. Chronic

Once RRD is confirmed, whether the fovea itself has detached is the single most important prognostic variable. A detachment that has reached the fovea is classified macula-off; one that hasn't is macula-on. Macula-off detachments carry a worse visual prognosis no matter how quickly they're repaired. Macula-on detachments get the greater surgical urgency, precisely because prompt repair can still keep the fovea from ever detaching at all. The whole surgical timeline is built around catching the detachment before it crosses that line, not after.

A long-standing detachment can be recognized by a demarcation line, sometimes called a high-water mark: a pigmented line at the border between attached and chronically detached retina, formed by RPE proliferation along that junction. Its presence helps estimate chronicity and tells apart a slow, long-standing detachment from an acute, rapidly progressive one.

Degenerative retinoschisis belongs on the differential too, though it's a distinct entity: a splitting of the retina into two layers rather than a true separation from the RPE. Unlike RRD, it's typically stationary, produces an absolute rather than relative field defect that matches the schisis cavity exactly, and shows none of the pigment demarcation, mobile membrane, or progressive course of a real detachment. That distinction matters whenever a peripheral elevation turns up incidentally and doesn't fit the acute RRD picture.

Related Topics

Continue exploring Retina & Vitreous: