Retinal Tears and Detachment
Retinal breaks may result as the PHM peels away from the retina during the process of PVD. The pathogenesis is presumed to be due to excessive traction of the PHM on an area of the retina predisposed to tearing. Tear formation is usually associated with migration of retinal pigment epithelial cells from under the neurosensory retina into the vitreal cavity. These cells, if present, are seen as pigment granules or fragments in the anterior vitreous and should not be confused with red blood cells (which tend to be smaller and more refractile) (Figure 6). Retinal pigment epithelial cells can also contribute to the symptom of floaters.
Retinal breaks secondary to PVD are usually in the form of horseshoe tears that may occasionally convert to operculated round holes if PHM separation extends anteriorly with time. Rarely, giant retinal tears can develop, especially in predisposed individuals (e.g., in patients with Stickler syndrome). The incidence of retinal tears in patients with symptomatic PVD is reported to be 8% to 22%, and these tears frequently occur in the superotemporal quadrant of the retina.[24,30,31,32,33] Retinal tears can also develop in cases of asymptomatic PVD, with a reported prevalence of 4% to 6%.[24,29]
While it is generally accepted that retinal tear formation represents a one-time event, some eyes do develop successive retinal tears over a period of years. In a recent study, it has been estimated that 3.7% of eyes with initial uncomplicated PVD develop subsequent retinal tears at 6 weeks follow-up.
Retinal detachment, defined as the presence of subretinal fluid extending beyond 1 disk diameter of the edge of the tear, is estimated to occur in 3% to 7% of eyes with symptomatic PVD.[32,36] Why some retinal tears remain flat while others accumulate subretinal fluid is an area of current active research. Furthermore, the progression rate of retinal detachment is highly variable among patients as well as between eyes of the same patient.
Several intrinsic factors increase the risk of rhegmatogenous complications with PVD. Lattice retinopathy and myopia have long been recognized as important risk factors for retinal tears and detachment.[38,39]
Abnormal gel architecture as a risk 172 Comp Ophthalmol Update 6 (4) July-August 2005 ANG factor is equally as important, but it is perhaps less recognized. Characteristic gel changes can be seen in vitreoretinal syndromes such as Stickler syndrome and are diagnostic in most cases. Stickler patients run a high lifetime risk of developing retinal breaks and detachments. Some healthy patients who develop rhegmatogenous complications demonstrate an abnormal gel structure characterized by excessive fibrillary degeneration and syneresis disproportionate to their age and refractive error. The risk of retinal tears and detachments in these patients, however, is not well characterized.
Early onset nuclear sclerotic cataract and family history of retinal tear or detachment are other important intrinsic risk factors to consider.
Acquired risk factors include previous complicated or intracapsular cataract surgery, penetrating eye injury, and uveitis (in particular, panuveitis and infectious uveitis).[40,41,42,43]
© 2005 Comprehensive Ophthalmology Update, LLC
Cite this: Posterior Vitreous Detachment: Current Concepts and Management - Medscape - Jul 01, 2005.