Eyeworld

EW RESIDENTS 33 details of operative techniques, and intraoperative complications. The long period of analysis from 1999 to 2008, while allowing for an in- creased sample size, limited the stan- dardization of patient care due to advances in methods of assessing macular edema and techniques of cataract surgery. One question the authors hoped to answer is whether diabetic retinopathy increases after cataract surgery. Here, they reported progres- sion of diabetic retinopathy in 35% of patients following cataract sur- gery. However, there is no age- matched control of diabetic patients to compare post-op progression of retinopathy with the natural history of the disease. The grading system used for retinopathy classification differed from that used in the Early Treat- ment of Diabetic Retinopathy Study (ETDRS) and the Diabetes Control and Complications Trial (DCCT). We have some specific concerns with the grading system applied. First, the presence of hard exudates in the cur- rent study placed an eye in the mod- erate/severe category, whereas in ETDRS and DCCT, hard exudates in the presence of microaneurysms were considered mild non-prolifera- tive diabetic retinopathy (NPDR). Hard exudates are not a good marker of retinopathy severity as they may actually appear or increase as macu- lar edema is resolving. Second, se- vere retinal hemorrhages in four quadrants would be classified as mild in the current study, but as se- vere NPDR in ETDRS and DCCT. These patients, at risk for progres- sion to proliferative diabetic retinopathy (PDR), would not be identified in the current study. To better understand how this classifi- cation system affected the reported rate of progression, it would have been helpful if the authors had pro- vided data about the percent of pa- tients in each category pre- and post-op. Interestingly, the authors ulti- mately concluded that the observed worsening of retinopathy following cataract surgery is actually "pseudo- progression," attributable to im- proved visualization of previously existing retinopathy following lens extraction. Although speculative, this conclusion seems reasonable. The authors reported a 4% inci- dence of post-op CSME among the study group; however, as the authors pointed out, this rate is low com- pared to previous studies and needs to be interpreted with caution. Al- though macular edema is clearly de- fined in many of the seminal studies of macular edema, these studies were undertaken prior to the devel- opment of OCT. Over the past decade, the development and imple- mentation of OCT technology has improved our ability to detect mac- ula edema. However, standardized OCT criteria for macular edema have not yet been developed. A major weakness of this study is that the authors used different methods of detecting macular edema throughout the study period, such as stereo photography, two-dimen- sional photography, and optical co- herence tomography, and did not clearly define CSME for some of these modalities. Each of these modalities has a different level of sensitivity and specificity. Photogra- phy is less sensitive for detection of macular edema than OCT. Using hard exudates as the sole surrogate marker may inaccurately estimate the rate of development of post-op CSME. Lastly, although OCT was used in evaluation of CME for some of the study patients, the authors did not standardize their definition of macular edema using this modality. Another element that may have contributed to the low incidence of CSME is the possible use of non- steroidal anti-inflammatory agents or steroids, which can be used in the pre-op or post-op setting to reduce the likelihood of macular edema de- velopment post-op. The authors do not comment on whether such med- ications were used in their study population. Finally, the time of the post-op assessment after cataract surgery was not standardized. Although patients were required to have at least one post-op visit within 1 year following cataract surgery, data from the first post-op visit was used. Macular edema often develops after 1 to 2 months in the post-op period. Some patients may have returned for fol- low-up earlier, prior to the develop- ment of macular edema. Using data from a large cohort, this study supports the common practice of performing cataract sur- gery on many patients with diabetic retinopathy with visually significant cataracts. It raises interesting ques- tions about factors associated with post-op visual acuity among diabetic patients undergoing cataract surgery. Not surprisingly, the authors found that post-op visual acuity was posi- tively correlated with pre-op BCVA and negatively correlated with de- gree of retinopathy and age. They also found that patients with a his- tory of focal laser for CSME had a higher risk of not gaining BCVA after cataract surgery. Interestingly, the study did not find a correlation between level of pre-op diabetes control as measured by glycosylated hemoglobin and post-op visual acu- ity. This study excluded patients with prior or planned vitrectomy, active macular edema, and active proliferative diabetic retinopathy. Future studies examining results of cataract surgery in patients who have undergone vitrectomy would help us better understand the merits of cataract surgery in these patients. Overall, this study provides valuable information regarding vi- sual acuity outcomes and prognostic factors in diabetic patients who un- derwent phacoemulsification cataract surgery. However, the study limitations, particularly the ques- tionable grading system of diabetic retinopathy and the lack of stan- dardization in evaluating CSME, pre- vent us from drawing firm conclusions. Further multicenter prospective studies involving na- tional registry databases with stan- dardized techniques for the assessment of CSME and diabetic retinopathy would be helpful to give compelling answers. EW Contact information Loewenstein: john_loewenstein@meei. harvard.edu Visual acuity outcomes and prognostic factors" November 2011 Phacoemulsification cataract surgery in a large cohort of diabetes patients: Visual acuity outcomes and prognostic factors J Cataract Refract Surg (November) 2011; 37: 2006-2012 Christoffer Ostri, M.D., Henrik Lund-Andersen, M.D., D.M.Sc., Birgit Sander, Ph.D., Morten La Cour, M.D., D.M.Sc. Purpose: To assess visual acuity outcomes after phacoemulsification cataract surgery in a large population of diabetic patients with all degrees of diabetic retinopathy. Setting: Diabetology and ophthalmology unit, Copenhagen, Denmark Design: Cohort study Methods: This review of prospectively collected data comprised patients who had small-incision phacoemulsification cataract surgery between 1999 and 2008 (10 years) according to the Danish National Patient Registry. Results: Data of 7,323 diabetic patients were reviewed. Of these pa- tients, 285 had cataract surgery. The corrected distance visual acuity (CDVA) increased significantly after cataract surgery (P<.001; P<.05 in all diabetic retinopathy categories). The post-operative CDVA outcome was positively correlated with pre-operative CDVA and negatively corre- lated with the degree of diabetic retinopathy and age (P<.001). Patients with a history of focal laser treatment for clinically significant macular edema had a higher risk for not gaining from cataract surgery (P=.04; relative risk, 1.6). In post hoc analysis, the proportion of patients in the cohort without diabetic retinopathy appeared to increase the year be- fore cataract surgery (P=.03) and decrease the year after cataract surgery (P<.001). Conclusions: The CDVA increased significantly after phacoemulsifica- tion cataract surgery in diabetic patients regardless of the degree of dia- betic retinopathy. The apparent progression in diabetic retinopathy after modern cataract surgery seems to reflect the masking of low grades of diabetic retinopathy by pre-operative lens opacities. From the November issue of the Journal of Cataract and Refractive Surgery

• Cover