How to manage post-cataract retinal detachment

A comprehensive primer on risks and prevention.

By Kevin Suk, MD

Retinal detachment (RD) is a serious and potentially devastating complication of cataract surgery that occurs more frequently in pseudophakic eyes than phakic eyes. This implicates cataract surgery as a risk factor for RD.¹

The incidence of RD (Figure 1) after cataract surgery is approximately 1%, significant when compared with the general population, estimated at 0.006% to approximately 0.02% a year.^2-6 A recent study of 65,055 cases showed a 10-year cumulative incidence of 0.68%.⁷ The reported incidence, however, has varied widely from 0% to 3.6% depending on the population studied and the length of follow up.

Figure 1: A total retinal detachment. Visual prognosis is typically poor.

This article explores the relative risk of RD among patients undergoing cataract surgery and strategies to prevent this complication and manage it should it occur.

EVALUATING RISKS

Pseudophakia as a risk factor

Despite studies indicating a connection between RD in cataract patients vs. the general population, simply comparing these rates to determine the relative risk of post-cataract RD is problematic. Differences in study population, including patient demographics, axial length of the eye, cataract severity and complication rates make comparing these groups difficult.

To attempt to account for these confounding variables, a study using the Danish National Patient Registry compared the incidence of RD in pseudophakic eyes with the unoperated, phakic fellow eye as the control. The study included 202,226 patients and determined a fourfold increase in the relative risk of RD in pseudophakic eyes.⁸

Several risk factors exist for pseudophakic retinal detachment. Preoperatively, a RD in the fellow eye, male gender, age younger than 65 years and longer axial length (greater than 23 mm) increase the risk of a RD after cataract surgery.⁹ Peripheral lattice degeneration is also a noted risk factor.^9,10 Intraoperatively, surgical complications, including a posterior capsule tear, zonular dehiscence and vitreous loss, increase the risk of a RD. Postoperatively, Nd:YAG capsulotomy may be a risk factor, but the results are conflicting.⁹

Expectations crash down

Patient expectations after cataract surgery are high. With the advent of femtosecond laser-assisted cataract surgery, advanced surgical techniques and specialty IOLs, many patients achieve excellent visual outcomes. A complication as severe as a retinal detachment can be a dramatic deviation from the patient’s and surgeon’s expected outcomes.

When a RD occurs, the single operation success rate after repair is approximately 90% in uncomplicated cases.^11-14 Even with anatomic success, however, the visual outcome can be unpredictable and several factors can influence it.

Evaluating the initial postoperative risk

Understanding the complex pathogenesis of RD after cataract surgery aids in its prevention following surgery. The risk of RD is greatest in the first six months after surgery, increasing approximately ninefold.⁸

In fact, 50% to 75% of RDs occur in the first year after surgery.⁹ After this period, the relative risk decreases to about three times, which persists for 10 years after cataract surgery.⁸

Intraoperative complications

The risk of RD increases with complications during cataract surgery, namely posterior capsular tears and zonular dehiscence. Posterior capsular tears occur at a rate of 0.29% to 2.7% after cataract surgery, and zonular dehiscence occurs at a rate of 0.29% to 0.9%.^15-20

The increased risk of RD is likely secondary to vitreous loss and the resulting undue traction on the peripheral retina. As the pathophysiology of RD after cataract surgery includes excessive vitreous traction, it is understandable that more movement and manipulation of the vitreous will lead to retinal tears.

Risk beyond six months

After the first six months postoperatively, the risk of RD diminishes but still remains higher than in the unoperated phakic eye and persists so for up to 10 years.⁸ This implies a different pathophysiologic process may exist separate from the surgical manipulation, in which changes in the structure of the vitreous promote an anomalous posterior vitreous separation. After cataract surgery, molecular changes occur in the vitreous, with one consequence being that the cortical vitreous becomes more viscous than the anterior vitreous.

INDICATOR OF PROGNOSIS

Role of the fovea

The status of the fovea is the most significant influential factor. Patients with a post-cataract RD that spares the fovea typically fare much better than when the RD involves the fovea. Other factors that can affect the visual outcome include the duration of the detachment and the height of the macular detachment (Figure 2, page 29).^21,22

Figure 2: Visual recovery correlates with the height of the macular detachment.

Even after surgery for fovea-sparing RD, patients may not fully recover their preoperative visual function. Patients can have decreased contrast sensitivity after retinal detachment repair even when the fovea is intact and despite normal OCT findings.²³ The area of the previously detached retina will exhibit decreased retinal sensitivity.²⁴ A scleral buckle, if the surgeon uses this for repair, can induce refractive changes, including higher-order abberations.²⁵

Patients in whom the fovea is detached usually end up with a post-repair VA better than the preoperative measurement, but VA can still be quite poor.²¹ In those who do not fully recover VA, OCT can show disruption of the retinal architecture, such as loss of the inner segment/outer segment junction and external limiting membrane.²⁶ An epiretinal membrane, which occurs in approximately 9% of eyes after RD repair, can also limit post-repair VA.²⁷

PATHOGENESIS

Syneresis and synchisis

Molecular and structural changes in the vitreous, including syneresis and synchisis, typically occur in tandem as the adhesion between the cortical vitreous and the internal limiting membrane weakens, resulting in a physiologic posterior vitreous detachment.

In an anomalous posterior vitreous separation, the vitreous undergoes molecular and physical changes before the posterior vitreous cortex separates from the retina. The resulting imbalance of forces leads to focal traction on areas of vitreoretinal adhesion and formation of retinal tears.

Preventive strategies

When peripheral retinal pathology is asymptomatic, the decision whether to treat is not straightforward. Previous studies have suggested that most asymptomatic lesions do not require treatment,²⁸ but the cohort in these studies was not patients about to undergo cataract surgery. It is somewhat conjecture to translate these findings to the specific case of high-risk pre-surgical eyes. Without good level 1 or 2 evidence, no agreed upon guideline exists for when to treat asymptomatic lattice degeneration or retinal tears.³⁰

I tend to base my decision on a mental “risk score,” with each risk factor adding to the overall decision of whether to treat. High-risk features include retinal detachment in the fellow eye, long axial length, previous trauma and other systemic diseases, such as Marfan’s syndrome. Additional factors are absence of a posterior vitreous separation, evidence of traction on the lesion and associated subretinal fluid.

Peripheral retinal lesions are usually treated when they increase the risk of retinal detachment and include lattice degeneration, cystic retinal tufts and zonular traction tufts.³¹ Finally, cataract surgery, itself, is a risk factor that contributes to the overall risk score.

My threshold to treat is low when patients are to undergo intraocular surgery. Treatment is typically with two to three rows of laser surrounding the retinal tear or lesion (Figure 3, page 30). It is important to treat the retina anterior to the tear and the edges of lattice degeneration particularly well, because retinal tears develop from traction at the posterior and lateral margins, where the vitreous adheres tightly.³¹

Figure 3: Laser photocoagulation spots surround all edges of the retinal tear.

If such a complication arises during cataract surgery, the surgeon should aim all measures at minimizing traction. These include halting phacoemulsification to minimize aspirating vitreous into the needle, and then performing an anterior vitrectomy with visualization using diluted triamcinolone to separate the vitreous in the anterior chamber from the anterior hyaloid.

If any nuclear material has fallen into the vitreous cavity, do not attempt to retrieve it. When “fishing” for nuclear fragments in the vitreous, infusion from the phaco tip pushes the lens material deeper into the vitreous cavity while preferentially aspirating the vitreous (Figure 4). Suture the corneal incisions, then promptly refer the patient to a retina specialist.

Figure 4: “Fishing” for nuclear fragments that fall into the vitreous cavity increases the risk of a retinal tear.

Presence of lattice

Although the presence of lattice is a potentially modifiable risk factor, no consensus exists on the need to treat lattice degeneration or an asymptomatic retinal tear before cataract surgery. The generally accepted dogma is to treat tractional retinal tears when associated with symptoms such as photopsias and floaters.²⁸

Additional contributing factors

Vitreous traction on the peripheral retina from surgical manipulation, either directly in the case of vitreous loss or from the anterior-posterior movement of the anterior vitreous, may contribute to the initial heightened risk. The change in vitreous volume and anatomy after replacement of a large cataractous lens with a small flat IOL likely contributes as well.

Some investigators have suggested a unique pathogenesis, having noted a different pattern of retinal tears and retinal detachment in pseudophakic eyes, similar to findings previously observed in aphakic eyes. Pseudophakic retinal detachments may be less likely to present with vitreous hemorrhage, and the retinal tears are more likely to locate inferiorly. The RD is more likely to be extensive, involving more than three quadrants and also involves the macula more frequently.²⁹

MANAGE THE RISK FACTORS

Most patients do well after cataract surgery. Although RD after cataract surgery is uncommon, the patient can experience significant morbidity when it occurs. Proper identification and prompt management of the modifiable risk factors can help ensure good surgical outcomes. OM

REFERENCES

About the Author
	Kevin Suk, MD, practices at the Retina Institute of California in Arcadia, Calif. His e-mail address is ksuk@retina2020.com. Disclosure: Dr. Suk has no relevant conflicts to disclose.