The increased risk of developing rhegmatogenous retinal detachment (RRD) following cataract extraction is well recognized. With the evolution of cataract surgery from intracapsular, aphakic techniques to extracapsular techniques with posterior chamber intraocular lens placement, the incidence of pseudophakic retinal detachment appears to be diminishing.1 It is worthwhile, however, for the anterior segment surgeon to identify eyes that may be at risk and to recognize those cases requiring preoperative prophylactic therapy and/or possible consultation with the vitreoretinal specialist. Familiarity with the mechanism and pathogenesis of RRD and recommended guidelines for pre-surgical and post-surgical management of those eyes at increased risk for RRD permits the anterior segment clinician to play a major role in further diminishing the incidence of retinal detachment following successful cataract extraction.
Mechanism of Rhegmatogenous Retinal Detachment
A retinal detachment is a clinical entity in which the neurosensory retina separates from the retinal pigment epithelium (RPE). There are four major categories of retinal detachment. An RRD develops from a full-thickness retinal break. This type of retinal detachment is most common and is the category that will be discussed here. A traction retinal detachment, such as that developing in proliferative diabetic retinopathy, forms when vitreoretinal tractional adhesions act to separate the neurosensory retina from the retinal pigment epithelium. A combined tractional and rhegmatogenous retinal detachment most commonly occurs in the setting of tractional detachment with secondary retinal break formation. Finally, an exudative retinal detachment develops with loss of the blood-retinal barrier in response to an underlying disorder such as inflammation or tumefaction. The hallmark of this type of detachment is the shifting and dependent nature of the subretinal fluid and the lack of a full-thickness retinal break.
An RRD most often develops when vitreoretinal tractional forces, acting on a full-thickness break, cause liquefied vitreous gel to enter the subretinal space and separate the retina. Eye movement, causing internal eddy currents, may facilitate this process. Full-thickness retinal breaks bearing little or no traction, such as atrophic retinal holes and operculated flap tears, often pose less threat to subsequent detachment.2
Acute posterior vitreous separation often precedes the development of RRD. Aging causes syneresis of the vitreous gel. Large liquefied pockets of gel, also known as lacunae, form.2 With time, the liquefied gel passes into the subhyaloid space creating a true posterior vitreous separation.3 Increased age, increased axial length of the eye, prior intraocular surgery, and prior trauma, among other factors, may accelerate the development of a posterior vitreous detachment.
Following posterior vitreous separation, condensed cortical vitreous gel, in regions adherent to the inner retina, exerts traction on the retina. Typical flap-shaped tears are the result of these tractional forces, often occurring at the posterior insertion of the vitreous base. It is this type of retinal break that most often leads to detachment of the retina.
Pseudophakic Retinal Detachment
Nonphakic eyes are at an increased risk for retinal detachment in their lifetime when compared with phakic eyes. Approximately 40% of retinal detachments occur in the nonphakic eye.4 The incidence of retinal detachment is 0.01% in the general population, 2% to 5% following intracapsular cataract extraction, and 0% to 1.4% following extracapsular cataract extraction.4-12 Crystalline lens extraction is clearly associated with an increase in the rate of vitreous liquefaction and subsequent posterior vitreous detachment. This event is probably a result of the induced changes in the vitreous following lens extraction. An intact posterior capsule diminishes the risk of RRD in the non-phakic eye. A standard, uncomplicated extracapsular cataract extraction with posterior chamber intraocular lens implantation diminishes the risk of RRD when compared with prior techniques.1
The nonphakic retinal detachment has several identifiable characteristics. Multiple retinal breaks are common, and these breaks are often small and slit-like. The detachments most often occur during the first year following lens extraction, and the rate of detachment decreases substantially thereafter.
Nd:YAG laser destruction of the posterior capsule is associated with an increase in the rate of retinal detachment in the nonphakic eye. The rate of retinal detachment following Nd:YAG ablation of the posterior capsule may be greater in aphakic eyes than in eyes following either uncomplicated phacoemulsification or extracapsular cataract extraction.13 Additional associations with retinal detachment in eyes following Nd:YAG laser posterior capsulotomy may include increasing axial length, lattice degeneration, retinal detachment in the fellow eye, and younger age.13,14
Prophylaxis and Prevention of Retinal Detachment
The prevention of retinal detachment is a reasonable goal given the significant patient morbidity of the disease and the potential for visual loss and possible blindness. Successful anatomic retinal reattachment is achieved in approximately 95% of cases. With successful reattachment, visual acuity returns to 20/50 or better in approximately 50% of cases.15
The anterior segment surgeon, by limiting intraoperative complications, may decrease the risk of developing an RRD. Posterior capsular rupture with or without subsequent vitreous loss likely increases the risk of subsequent pseudophakic detachment.16,17 In addition, Nd:YAG laser ablation of the posterior capsule adds an incremental risk of retinal detachment.13,14
However, the primary method of preventing retinal detachment in the pre- and/or post-surgical (i.e., cataract surgery and Nd:YAG laser ablation of the posterior capsule) eye involves the recognition of vitreoretinal lesions at risk for subsequent complications. Performing retinopexy (laser or cryopexy) or observation alone may help limit the development of clinical retinal detachment.
A host of factors put a patient at increased risk for retinal detachment. Myopia, male gender, and family history of retinal detachment (hereditary vitreoretinopathies) are known risk factors for RRD. Others include a history of ocular trauma, retinal detachment in the fellow eye, and ocular inflammatory disease. Pre-existing lesions in the retina, such as lattice degeneration, cystic retinal tufts, and full-thickness retinal breaks, also place an eye at increased risk. Prior surgical interventions, whether cataract extraction, vitrectomy, or Nd:YAG posterior capsulotomy, increase the risk of retinal detachment as well.
It is the clinician’s responsibility to assess the overall risk of the eye to retinal detachment prior to surgical intervention. Retinal detachment occurs most frequently following symptomatic posterior vitreous detachment. Symptoms include photopsia and/or increased floaters that may accompany an acute posterior vitreous detachment. Therefore, asymptomatic eyes that have previously had a posterior vitreous separation without adverse sequelae are probably at less risk of developing an RRD following cataract extraction than are those eyes in which the posterior hyaloid has not separated.
Unfortunately, assessing an eye at risk is usually more involved than simply determining the status of the posterior vitreous. Prophylactic retinopexy for asymptomatic retinal lesions is a controversial therapy, and, to date, no prospective, randomized trial advocating prophylactic prevention has been published.18 When assessing the overall risk of an eye, the first determination is whether the patient is experiencing any symptoms.
A symptomatic patient should probably not undergo cataract extraction until symptoms such as photopsia either resolve or clearly diminish. In addition, symptomatic breaks with associated vitreoretinal traction should be treated with retinopexy to reduce the risk of subsequent detachment. However, asymptomatic retinal breaks without associated vitreoretinal traction can be safely observed.
When evaluating the relative risk of an asymptomatic eye, the surgeon should assess the extent of vitreoretinal pathology and other confounding factors. For instance, patients who have suffered a retinal detachment in their fellow eye are at greater risk for retinal detachment. If vitreoretinal pathology, such as cystic retinal tufts, lattice degeneration, and asymptomatic breaks, is present in a phakic eye, the potential benefit of prophylactic treatment of these lesions is generally accepted but unproven.
Asymptomatic aphakic and pseudophakic eyes are at an increased risk for retinal detachment. This risk is increased if secondary YAG laser capsulotomy is performed. As expected, this risk increases further if the posterior vitreous has not previously separated from the underlying retina. For this reason, prophylactic retinopexy is generally recommended for vitreoretinal lesions in fellow eyes with an adherent posterior vitreous that are nonphakic or that are scheduled to undergo cataract extraction. However, to date, recommendations for treatment are not substantiated by supportive data, and, thus, any intervention is best left to the judgment of the clinician.
When determining appropriate candidates for prophylactic intervention either prior to or following cataract extraction, published studies do not provide clear rules and indications. Clinical judgment, often with the input of both a vitreoretinal specialist and the patient, will often guide therapy. Additionally, it is important to understand that prophylactic retinopexy is not without risks. New retinal breaks, macular pucker, intraretinal and subretinal hemorrhage, and vitreous hemorrhage can be complications of excessive retinopexy.
Surgical Repair of the Nonphakic Retinal Detachment
The repair of the nonphakic retinal detachment may be achieved by several modalities. Conventional scleral buckling in the setting of aphakia and pseudophakia may have a lower initial anatomic success rate than in phakic individuals.19-21 This may be due to the small slit-like breaks often found in the nonphakic eye. Additionally, capsular opacification and fibrosis in the pseudophake can obscure the view of the peripheral fundus, rendering identification of causative breaks challenging.
Pars plana vitrectomy, sometimes in conjunction with scleral bucking, is a reasonable alternative surgical approach to the nonphakic retinal detachment. Recent advances in technology, such as panoramic visualization, liquid perfluorocarbons, and high-speed automated vitreous cutting, have facilitated the surgical management of the nonphakic detachment by vitrectomy. The peripheral retina is often better visualized during vitrectomy, and retinal breaks can be located in most situations, enhancing management. Additionally, drainage of subretinal fluid can be performed internally in a more controlled manner. Retinopexy via endophotocoagulation is applied directly, avoiding excessive and extensive cryopexy. Anatomic and visual outcomes are comparable to scleral buckling alone.22-24
Repair of the pseudophakic detachment with vitrectomy is often reserved for eyes in which there is adequate support of the previously placed intraocular lens. If support is compromised, displacement or dislocation of the intraocular lens may occur either intra- or postoperatively.
Other surgical options include pneumatic retinopexy and Lincoff balloon scleral buckles. Not all eyes are suitable candidates for these procedures. Eyes that respond favorably often have limited vitreoretinal pathology. Pneumatic retinopexy is often reserved for eyes in which the retinal breaks are located in the superior retina.25 Detachments with multiple breaks can be treated successfully with pneumatic retinopexy if the breaks are located in the same quadrant. Adequate postoperative head positioning on the patient's part is essential for a successful outcome.
Lincoff balloon scleral buckles are reserved for eyes in which pathology is quite limited. Detachments caused by small, single breaks often respond most favorably to this modality.26 Detachments with inferior retinal breaks can be treated effectively. Pneumatic retinopexy and balloon scleral buckling are office-based procedures and, as such, limit the incurred operating room expenses.
Cataract Extraction Following Retinal Reattachment Surgery
Anatomic results following cataract surgery in eyes that have undergone successful retinal reattachment surgery are favorable. The risk of complications is low, and visual results are influenced by the prior detachment and underlying retinal disease.27
Cataract extraction in eyes that have had prior vitrectomy presents specific challenges. Posterior capsular defects and focal zonular dehiscences as a result of previous vitrectomy may lead to complications during cataract extraction. Deepening of the anterior chamber during phacoemulsification, enhanced in vitrectomized eyes, can be problematic. However, with experience, surgical complications can often be avoided.
Retinal detachment following cataract surgery is a well-recognized problem. Preoperative prophylactic management in high-risk eyes may be beneficial in reducing this complication. In addition, patient education as to the symptoms and signs of retinal detachment may limit ultimate morbidity and visual loss. A basic understanding of the disease, its pathogenesis, and treatment options can help in optimizing visual outcomes following cataract surgery.