To assess the rate of ‘treatment-requiring diabetic macular oedema (DMO)’ in eyes for the two years before and after cataract surgery.Methods
Multicentre national diabetic retinopathy (DR) database study with anonymised data extraction across 19 centres from an electronic medical record system. Inclusion criteria: eyes undergoing cataract surgery in patients with diabetes with no history of DMO prior to study start. The minimum dataset included: age, visual acuity (all time-points), injection episodes, timing of cataract surgery and ETDRS grading of retinopathy and maculopathy. Main outcome measure: rate of developing first episode of treatment-requiring DMO in relation to timing of cataract surgery in the same eye.Results
4850 eyes met the inclusion criteria. The rate of developing treatment-requiring DMO in this cohort was 2.9% in the year prior to surgery versus 5.3% in the year after surgery (p<0.01). The risk of ‘treatment-requiring DMO’ increased sharply after surgery, peaking in the 3–6 months' period (annualised rates of 5.2%, 6.8%, 5.6% and 4.0% for the 0–3, 3–6, 6–9 and 9–12 months' post-operative time periods respectively). Risk was associated with pre-operative grade of retinopathy: risk of DMO in the first year post-operatively being 1.0% (no DR pre-operatively), 5.4% (mild non-proliferative diabetic retinopathy; NPDR), 10.0% (moderate NPDR), 13.1% (severe NPDR) and 4.9% (PDR) (p<0.01).Conclusions
This large real-world study demonstrates that the rate of developing treatment-requiring DMO increases sharply in the year after cataract surgery for all grades of retinopathy, peaking in the 3–6 months' postoperative period. Patients with moderate and severe NPDR are at particularly high risk.