Dealing with Retinal Conditions in Cataract Surgery Patients
Guidance for our anterior segment colleagues.
STEPHEN G. SCHWARTZ, MD HARRY W. FLYNN, JR., MD
Cataract surgery remains the most common surgical procedure in the United States, with over 2 million performed yearly.1,2 Many of these patients have concomitant retinal disease, which may influence the decision to recommend surgery and may limit the ultimate visual outcome. Certain retinal diseases may be exacerbated by cataract surgery, although the peer-reviewed evidence for this risk is controversial.
In this article, general principles regarding the evaluation of the cataract patient with retinal disease are reviewed. Current recommendations regarding cataract surgery for 3 common groups of retinal patients are targeted: those with diabetic macular edema (DME), age-related macular degeneration (AMD), and peripheral retinal disease.
Figure 1: Optical coherence tomography image showing vitreomacular traction syndrome.
Rather than any particular surgical complication, a not uncommon cause of a disappointing visual result following cataract surgery is unrecognized retinal disease. Therefore, identifying concomitant retinal pathology, which may be subtle, is an important part of the preoperative evaluation as well as the informed consent.
It may be difficult to discriminate between vision loss from cataract and vision loss from retinal pathology. Although potential acuity meter (PAM) testing is frequently helpful, various tests of reading performance may also give useful information.3
In patients with more advanced cataract, ophthalmoscopy as well as fundus photography and fluorescein angiography may be hindered to variable degrees. Optical coherence tomography (OCT) may give surprisingly good images through relatively small pupils and moderately dense lens opacities (Figure 1). OCT is invaluable in patients with an abnormal-appearing macula who are considering cataract surgery. Other testing (such as fluorescein or indocyanine green angiography) may be used, but are not generally used as a screening tool.
In patients with very dense cataract, precluding a good view of fundus details, B-scan echography is generally indicated, primarily to rule out retinal detachment (RD) or other advanced posterior-segment disease (Figure 2). In addition, examination of the fellow eye, when possible, may offer important clues (for example, the presence of macular drusen, diabetic retinopathy, and other conditions). The presence of a relative afferent pupillary defect in the cataractous eye may also indicate advanced retinopathy and/or optic neuropathy.
Previous pars plana vitrectomy (PPV) is a risk factor for complicated cataract surgery due to many factors, including abnormal fluctuations in anterior chamber depth.4 The anterior-segment surgeon should be prepared for capsular rupture and posterior dislocation of lens fragments in these patients. When evaluating patients with macular hole or epiretinal membrane, consideration should be given to cataract surgery either prior to, or concomitant with, PPV.
DIABETIC MACULAR EDEMA (DME)
Figure 2: Dense cataract blocking a view of posterior segment details.
Recommendations from the peer-reviewed data regarding the risk of DME progression following cataract surgery are inconsistent. In the pseudophakic eye, the distinction between DME and pseudophakic (Irvine-Gass) cystoid macular edema (CME) may be difficult. Nevertheless, multiple retrospective studies and small case series have reported an increased risk of progression of diabetic retinopathy, including macular edema, following cataract surgery.5-7 On the other hand, the Early Treatment Diabetic Retinopathy Study Report Number 258 reported: "No statistically significant long-term increased risk of macular edema was documented after lens surgery."
It appears prudent to stabilize any pre-existing diabetic retinopathy prior to elective cataract surgery. Treatment of clinically significant macular edema with photocoagulation or other means (for example, intravitreal triamcinolone acetonide or bevacizumab), prior to cataract surgery, is generally recommended. Similarly, proliferative diabetic retinopathy and CME due to retinal vein occlusions are usually treated, as appropriate, prior to cataract surgery. Ideally, cataract surgery can be delayed until OCT demonstrates improvement of macular edema.
In patients with dense cataract, photocoagulation may not be possible. In this circumstance, treatment may be applied several weeks after cataract surgery, once the incision has healed sufficiently to allow placement of a contact lens.
AGE-RELATED MACULAR DEGENERATION (AMD)
Similar to DME, the true risk of progression of AMD following
cataract surgery is controversial. Pooled data from 3 large population-based studies
indicate a correlation between late AMD (choroidal neovascularization [CNV] or geographic
atrophy) and a history of cataract surgery, although the authors of this study emphasized
that this finding does not necessarily imply a causal link.9
At the present time, unpublished data from the Age-Related Eye Disease Study
show "no definite increased risk of either CNV or geographic atrophy following
(F. Ferris, personal communication).
Occult CNV may be under-recognized in this population. Some patients with CNV lack ophthalmoscopically obvious subretinal fluid, hemorrhage, or lipid exudate, particularly when viewed through a moderately dense cataract. In this setting, OCT is very helpful in identifying CME, subretinal fluid, or sub-retinal pigment epithelial fluid, indicating wet AMD.
Patients with CNV are generally treated prior to cataract surgery, using pegaptanib, bevacizumab, verteporfin, photocoagulation, or other agents as appropriate. Similar to DME, delaying cataract surgery until the OCT indicates improvement of CME and/or subretinal fluid is usually recommended.
Figure 3: Flap retinal tear with bridging vessel treated with argon laser photocoagulation to surround the lesion.
PERIPHERAL RETINAL BREAKS
Independent risk factors for rhegmatogenous RD following cataract surgery include prior history of RD, Nd:YAG capsulotomy, lattice degeneration, increased axial length, myopia, and ocular trauma.10 The 4-year cumulative risk of RD following cataract surgery is probably less than 1%.11 Theoretically, the risk is lower in eyes with a pre-existing posterior vitreous detachment.
The American Academy of Ophthalmology's Preferred Practice Patterns12 offer excellent guidelines. Specifically, flap retinal tears (even when asymptomatic) are usually treated (Figure 3). Round retinal holes, lattice degeneration, white without pressure, and other peripheral retinal abnormalities are typically observed.
In the setting of a dense cataract with a rhegmatogenous retinal detachment, PPV with concomitant pars plana lensectomy is generally recommended. The decision to place an intraocular lens at the time of surgery is individualized for each patient.
In general, retinal diseases with the potential for progression such as DME, CNV, and retinal tears are evaluated and treated, when possible, prior to cataract surgery. Patients with visually significant lens opacities, and stable retinal conditions should be offered cataract surgery when, in the judgment of the physician, they are likely to benefit. Following these general principles, reasonable patient expectations can be emphasized, to avoid the surprise of a less-than-perfect visual outcome from cataract surgery.
Stephen G. Schwartz, MD, and Harry W. Flynn, Jr., MD, are retina specialists affiliated with Bascom Palmer Eye Institute in Miami.
1. Rahmani B, Tielsch JM, Katz J, et al. The cause-specific prevalence of vision impairment in an urban population. The Baltimore Eye Survey. Ophthalmology. 1996;103:1721-1726.
2. Steinberg EP, Javitt JC, Sharkey PD, et al. The content and cost of cataract surgery. Arch Ophthalmol. 1993;111:1041-1049.
3. Stifter E, Weghaupt H, Benesch T, Thaler A, Radner W. Discriminative power of reading tests to differentiate visual impairment caused by cataract and age-related macular degeneration. J Cataract Refract Surg. 2005;31:2111-2119.
4. Cheung CMG, Hero M. Stabilization of anterior chamber depth during phacoemulsification cataract surgery in vitrectomized eyes. J Cataract Refract Surg. 2005;31:2055-2057.
5. Jaffe GJ, Burton TC. Progression of nonproliferative diabetic retinopathy following cataract extraction. Arch Ophthalmol. 1988;106:745-9.
6. Jaffe GJ, Burton TC, Kuhn E, Prescott A, Hartz A. Progression of nonproliferative diabetic retinopathy and visual outcome after extracapsular cataract extraction and intraocular lens implantation. Am J Ophthalmol. 1992;114:448-456.
7. Cunliffe IA, Flanagan DW, George ND, Aggarwaal RJ, Moore AT. Extracapsular cataract surgery with lens implantation in diabetics with and without proliferative retinopathy. Br J Ophthalmol. 1991;75:9-12.
8. Chew EY, Benson WE, Remaley NA, et al. Results after lens extraction in patients with diabetic retinopathy. Early Treatment Diabetic Retinopathy Study Report Number 25. Arch Ophthalmol. 1999;117:1600-1606.
9. Freeman EE, Munoz B, West SK, Tielsch JM, Schein OD. Is there an association between cataract surgery and age-related macular degeneration? Data from three population-based studies. Am J Ophthalmol. 2003;135:849-856.
10. Tielsch JM, Legro MW, Cassard SD, et al. Risk factors for retinal detachment after cataract surgery. A population-based case-control study. Ophthalmology. 1996;103:1537-1545.
11. Norregaard JC, Thoning H, Andersen TF, et al. Risk of retinal detachment following cataract extraction: Results from the International Cataract Surgery Outcomes Study. Br J Ophthalmol. 1996;80:689-693.
12. American Academy of Ophthalmology. Posterior Vitreous Detachment, Retinal Breaks, and Lattice Degeneration, Preferred Practice Pattern. San Francisco: American Academy of Ophthalmology, 2003.