6
Prevention of Retinal Detachment
Retinal detachment is an uncommon disease, affecting approximately 1 in 10,000 people in the general population per year. However, the incidence of retinal breaks is relatively high, affecting 5% to 7% of the population.
Obviously, many retinal breaks have minimal, if any, risk for the possible development of a retinal detachment. This includes macular holes that occur as a degenerative process, and asymptomatic, small, round atrophic holes near the ora serrata. However, equatorial horseshoe tears with relevant symptoms progress to retinal detachment in most cases.
Probably all surgeons would agree that a large horseshoe tear near the equator in the superior temporal quadrant, with new-onset symptoms of flashes and floaters and associated vitreous hemorrhage, should be treated prophylactically to avoid retinal detachment. In contrast, most would not advise treatment of a small, round atrophic hole near the inferior ora serrata in an asymptomatic patient with no history of prior detachment. Between these two obvious examples lies a broad spectrum of retinal breaks for which the surgeon must exercise judgment about instituting prophylactic treatment.
Most of the breaks reported in surveys of asymptomatic patients or in autopsy series are of the atrophic type, and only a small proportion are horseshoe tears. Although there are no specific rules for the selection of patients for treatment, and each case has to be judged on its own characteristics, the application of evidencebased medicine to this topic has modified the opinions of many regarding the genuine value of prophylactic therapy for most retinal breaks.
The American Academy of Ophthalmology has used this approach in developing a Preferred Practice Pattern (PPP) entitled “Posterior Vitreous Detachment, Retinal Breaks, and Lattice Degeneration,” the latest version of which was published in
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2008. The evidence base described in this PPP will be employed in the following discussion.
RISK FACTORS FOR RETINAL DETACHMENT
Characteristics associated with a relatively high risk of retinal detachment in an eye with visible retinal breaks are listed in Table 6–1. Symptoms and signs of PVD place an eye at particularly high risk. Additional factors include a variety of hereditary, congenital, acquired, and iatrogenic problems.
The risk of retinal detachment is substantially different among subgroups of eyes, a fact that influences interpretation of both natural history data and treatment results. For example, since an acute PVD is the primary cause of most retinal detachments, and since most retinal tears occur during or soon after PVD, it is likely that eyes without a PVD have a higher risk of later retinal detachment than eyes with a history of prior PVD. Similarly, vitreous liquefaction and PVD occur with greater frequency in older patients and in myopic and nonphakic eyes. Thus, data regarding lesions in otherwise normal, young, nonmyopic eyes are not comparable with data from cases with other risk factors that greatly increase the likelihood of PVD. Since more than one factor is often present, data analysis is difficult if all features are not recorded. For example, myopic pseudophakic eyes with lattice degeneration and with a history of retinal detachment in the fellow eye have a substantially greater risk of retinal detachment than otherwise normal eyes with lattice degeneration.
Table 6–1. Risk Factors for Rhegmatogenous Retinal Detachment
Symptomatic posterior vitreous detachment (PVD)
Hereditary/congenital/developmental/degenerative lesions
Male gender
Hereditary vitreoretinopathies
Myopia
Lattice degeneration with and without holes
Cystic retinal tuft
Degenerative retinoschisis
Retinal breaks
Symptomatic horseshoe tear
Dialysis
Prior ocular surgery
Aphakia/pseudophakia
Nd:YAG posterior capsulotomy
Other surgery involving vitreous gel
Prior trauma
Inflammation
CMV retinitis
Acute retinal necrosis
Other
Fellow eye non-traumatic retinal detachment
6: Prevention of Retinal Detachment |
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As noted in the Academy PPP, no prospective randomized trials of therapy to prevent retinal detachment have been performed. The few meaningful published studies of treated and untreated comparable eyes have been retrospective, and most reports regarding prophylactic therapy have simply described results of a treatment series.
This chapter briefly discusses published outcomes regarding both the natural course of lesions that predispose an eye to retinal detachment and results of prophylactic therapy for these lesions. A thorough review of treatment techniques is beyond the scope of this chapter, although they will be briefly discussed along with complications of therapy.
SYMPTOMATIC EYES
Patients are considered symptomatic if they describe suddenly increased vitreous floaters and/or photopsia associated with an acute posterior vitreous detachment. Approximately 15% of eyes with an acute symptomatic PVD develop retinal tears of various types. The risk of retinal tears is directly related to the amount of vitreous hemorrhage, and the finding of pigmented cells in the vitreous is a sign associated with a particularly high chance of associated retinal tear(s). In symptomatic eyes, retinal tears associated with persistent vitreoretinal traction are especially likely to cause retinal detachment.
Retinal tears resulting from a symptomatic PVD should be distinguished from preexisting retinal breaks detected after the PVD but not caused by it. Thus, atrophic retinal holes within areas of lattice degeneration are not considered “symptomatic,” even if they were first observed during an examination prompted by symptoms of an acute PVD. Symptomatic retinal tears are subdivided into those with persistent vitreoretinal traction and those in which all traction in the region of the retinal defect has resolved (Figure 6–1).
TEARS WITH PERSISTENT VITREORETINAL TRACTION
Symptomatic horseshoe-shaped tears
Most symptomatic tears with persistent vitreoretinal traction are horseshoe shaped and have a high risk of causing clinical retinal detachment. That risk has been reported to be in the range of 33% to 55% of cases. Treatment of this type of break substantially reduces the risk of retinal detachment, and immediate prophylactic therapy for these lesions is indicated to prevent an accumulation of subretinal fluid (Academy PPP evidence level A:II). A chorioretinal adhesion is created in flat retina immediately adjacent to localized subretinal fluid.
Symptomatic round tears
Rarely, a retinal tear with a free operculum may have persistent vitreoretinal traction as a result of a residual vitreoretinal adhesion near the retinal break, most frequently at the location of a retinal blood vessel. Only two symptomatic operculated retinal breaks have been reported to progress from initial observation to retinal detachment,
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Figure 6–1. Horseshoe tears are associated with persistent vitreoretinal traction upon the flap of the tear (white arrow), whereas operculated tears no longer have traction forces acting upon them (dark arrow) unless there is a nearby vitreoretinal adhesion.
and both were associated with persistent vitreoretinal traction on nearby retinal vessels. In unusual cases in which an operculated retinal hole is the only retinal break associated with a clinical retinal detachment, it is presumed that anomalous persistent vitreoretinal adhesions are located in the vicinity of the retinal tear. Treatment of these breaks may be recommended if the presence of a nearby vitreoretinal adhesion cannot be ruled out (Academy PPP evidence level A:III). Failures following treatment of operculated retinal holes have not been reported.
BREAKS UNASSOCIATED WITH PERSISTENT VITREORETINAL TRACTION
Symptomatic operculated retinal tears
Tears unassociated with persistent vitreoretinal traction in the vicinity of the retinal break have not been reported to progress to clinical retinal detachment. Similarly, although large numbers of these breaks have been treated prophylactically, there are no reports in the literature of a treatment failure. Treatment of this type of retinal break appears to be unnecessary unless the possibility of persistent vitreoretinal traction cannot be excluded (Academy PPP evidence level A:III).
Symptomatic atrophic retinal holes and precursors of retinal breaks
Eyes with symptoms and signs of acute PVD frequently contain atrophic retinal breaks that are not due to acute vitreoretinal traction. For the purposes of this discussion, these lesions are considered to be preexisting and not symptomatic and are discussed in a later section. Similarly, precursors of retinal breaks or detachment, including lattice degeneration, cystic retinal tufts, and age-related retinoschisis, are managed as if they were originally discovered in asymptomatic eyes.