Retinal detachments are classified as rhegmatogenous, tractional, or exudative. The most common are rhegmatogenous retinal detachments (RRDs). The term is derived from the Greek rhegma, meaning “break.” RRDs are caused by fluid passing from the vitreous cavity through a retinal break into the potential space between the sensory retina and the RPE. Tractional detachments are caused by proliferative membranes that contract and elevate the retina; these are less common. Combinations of tractional and rhegmatogenous pathophysiologic components may also lead to retinal detachment. Exudative, or secondary, detachments are caused by retinal or choroidal diseases in which fluid leaks beneath the sensory retina and accumulates there.
The differential diagnosis of retinal detachment includes retinoschisis, choroidal tumors, and retinal elevation secondary to detachment of the choroid. Table 16-2 lists diagnostic features of the 3 forms of retinal detachment.
Rhegmatogenous Retinal Detachment
The Rochester epidemiology project determined that rhegmatogenous retinal detachment has an annual incidence of 12.6 per 100,000 persons in a primarily white population. A given individual’s risk is affected by the presence or absence of certain factors, including myopia, family history, fellow-eye retinal tear or detachment, recent vitreous detachment, trauma, peripheral high-risk lesions, and vitreoretinal degenerations. Current or recent use of fluoroquinolones may also be a risk factor, but the evidence for a causal relationship is controversial.
In 90%–95% of RRDs, a definite retinal break can be found, often with the help of Lincoff rules (Figs 16-13, 16-14). In the remainder, an occult break is presumed to be present. If no break can be found, the ophthalmologist must rule out all other causes of retinal elevation. Half of patients with RRD have photopsias, or floaters. The intraocular pressure is usually lower in the affected eye than in the fellow eye but may occasionally be higher. A Shafer sign, descriptively termed “tobacco dust” due to its small clumps of pigmented cells, is frequently present in the anterior vitreous. The retina detaches progressively from the periphery to the optic nerve head; usually it has convex borders and contours and a corrugated appearance, especially in recent retinal detachments, and undulates with eye movements. In a long-standing RRD, however, the retina may appear smooth and thin. Fixed folds resulting from proliferative vitreoretinopathy (PVR) almost always indicate an RRD. Shifting fluid may occur, but it is uncommon and more typical of serous retinal detachments.
PVR is the most common cause of failure following surgical repair of an RRD. In PVR, retinal pigment epithelial, glial, and other cells grow and migrate on both the inner and outer retinal surfaces and on the vitreous face, forming membranes. Contraction of these membranes causes fixed retinal folds, equatorial traction, detachment of the nonpigmented epithelium from the pars plana, and generalized retinal shrinkage (Fig 16-15). As a result, the causative retinal breaks may reopen, new breaks may occur, or a tractional detachment may develop.
Table 16-2 Diagnostic Features of the 3 Types of Retinal Detachments
Figure 16-13 Using Lincoff rules to find the primary break.
(Used with permission from Kreissig I. A Practical Guide to Minimal Surgery for Retinal Detachment. Vol 1. Stuttgart, New York: Thieme; 2000:13–18. © Thieme.)
Figure 16-14 Color fundus photograph of a horseshoe retinal tear with a bridging vessel and secondary retinal detachment. Intact retinal vessels can bridge a tear, whereas some vessels crossing a flap tear can rupture and bleed into the vitreous cavity. Along with photopsia, initial symptoms may include black spots from the vitreous hemorrhage.
Figure 16-15 Color fundus photograph of a retinal detachment with proliferative vitreoretinopathy. Revised Retina Society classification CP-12 with diffuse retinal contraction in posterior pole (arrow) and single midperipheral starfold (arrowhead). See Table 16-3.
To better compare preoperative anatomy with postoperative outcomes, researchers developed a classification of PVR (Table 16-3). The 1991 classification lists 3 grades of PVR (A, B, and C), which correspond to increasing severity of the disease. Anterior and posterior involvement (CA, CP) are distinguished and subclassified into focal, diffuse, subretinal, circumferential, and anterior displacement. The extent of the pathology is described in clock-hours.
Table 16-3 Classification of Proliferative Vitreoretinopathy, 1991
Han DP, Lean JS. Proliferative vitreoretinopathy. In: Albert DM, Miller JW, Azar DT, Blodi BA, eds. Albert & Jakobiec’s Principles and Practice of Ophthalmology. Philadelphia: Saunders; 2008:chap 183.
Rowe JA, Erie JC, Baratz KH, et al. Retinal detachment in Olmsted County, Minnesota, 1976 through 1995. Ophthalmology. 1999;106(1):154–159.
Management of rhegmatogenous retinal detachment
The principles of surgery for retinal detachment are as follows:
The most important element in management of retinal detachment is a careful retinal examination, first preoperatively and then intraoperatively. Retinal breaks can be closed by several methods, all of which involve bringing the RPE and choroid into contact with the retina long enough to produce a chorioretinal adhesion that will permanently wall off the subretinal space. This process usually involves 1 of 3 approaches: (1) scleral buckling, (2) vitrectomy, or (3) pneumatic retinopexy. For acute, macula-on retinal detachments with symptoms, surgery is performed urgently. In contrast, in eyes with chronic retinal detachments with pigmented demarcation lines, treatment may be delayed or it may not be needed, if the eye continues to be monitored closely (Fig 16-16). See Chapter 20 for a more detailed discussion of these techniques and outcomes.
Figure 16-16 Chronic retinal detachment. At initial examination, patient presented with an asymptomatic large retinal detachment with a pigmented and atrophic demarcation line. No progression was observed over several weeks, and surgery was performed electively.
(Courtesy of Stephen J. Kim, MD.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.