Research conducted on behalf of the UK Diabetic Retinopathy Electronic Medical Record (UK DR EMR) Users Group has shown that the rate of developing “treatment-requiring” diabetic macular oedema (DMO), following cataract surgery, increases dramatically, peaking in the 3-6 months’ postoperative period. In addition, the research demonstrated that patients with moderate and severe non-proliferative diabetic retinopathy (NPDR) are at particularly high risk. The research suggests that outcomes may improve with a pre-operative DR severity status screen and OCT of both eyes, in addition to increased post-operative monitoring.
While changes in the ocular microenvironment following cataract surgery have been previously reported, clinical studies regarding DMO after cataract surgery have been inconclusive and most reported studies have less than 100 patients. The UK researchers undertook a “real world” study to obtain a more accurate picture of the heterogeneous populations seen in clinical practice. As the artificial environment of the traditional randomised controlled trial (RCT) often obscures treatment effects, studying broader population sets provide an opportunity to obtain more accurate and generalizable data useful in managing more efficient clinical care.
The research protocol extracted data on 123,968 eyes from 61,984 patient records, spanning subjects with various diabetic retinopathy grades, and with no diabetic retinopathy. Of the patient records analysed, 33,967 were male and 28,002 were female, while 15 cases of unrecorded gender were additionally included. Following analysis and exclusion of ineligible patients, 4,850 eyes from 3,837 patients were included in the study. These comprised of eyes undergoing cataract surgery in patients with diabetes, with retinopathy grade(s) recorded in the 2 years before and after surgery, and who had not developed DMO requiring treatment prior to study entry. The final study group comprised 1,719 eyes with no apparent diabetic retinopathy (DR), 1,034 with mild NPDR, 1,527 with moderate NPDR, 165 with severe NPDR, and 405 with proliferative DR. Results showed that the percentage of eyes developing a first episode of “treatment-requiring DMO” increased from 2.9% in the year immediately prior to surgery to 5.3% in the first year, and 4.8% in the second year post-surgery; the highest risk period was between 3 and 6 months post-surgery, while 1.7% of eyes developed a first episode of “treatment-requiring DMO” during the initial 3-month period, equating to an annualised risk of 6.8%.
Commenting on the results, the study authors stated, “this analysis of a real world dataset achieved at a large number of centres across the UK indicates an increased rate of developing visually significant DMO in the post-operative phase, with a particularly high risk from 3 to 9 months. The UK requirement for an OCT-defined threshold of DMO to access ranibizumab treatment, and the presence of a clear post-operative DMO spike in this cohort provides further evidence that this is a real increase in DMO and not just an issue of visualisation. We would recommend that assessment prior to cataract surgery for any patient with diabetes should include a record of DR severity status and a macular OCT of both eyes, while recognising that the lens opacities may limit assessment in some eyes. There may also be a role for increased monitoring of patients with even relatively mild diabetic retinopathy during the post-operative phase to help detect DMO and enable earlier treatment.”