Purpose To evaluate the effect of previous vitrectomy on the incidence of macular oedema (MO) after cataract surgery in diabetic eyes.

Methods Ninety phakic eyes of 70 patients with diabetes undergoing non-emergent vitrectomy surgery were reviewed for rates of postvitrectomy MO, cataract formation and postcataract surgery MO. Preoperative and final best-corrected visual acuity were recorded. Baseline risk characteristics were analysed.

Results Postvitrectomy MO increases initially but then levels off at 28% by 4 years. Cumulative proportion of eyes requiring cataract surgery after vitrectomy climbs steadily, reaching 40% at 4 years and 60% at 8 years. Of those eyes which underwent vitrectomy and then subsequent cataract surgery, the incidence of postvitrectomy MO was 6% at 6 months, and that of postcataract surgery MO was 30% at 6 months (p<0.02). Previous clinically significant macular oedema (CSMO) predicted development of postcataract surgery MO (p<0.04).

Conclusions Previous vitrectomy does not appear to lessen rates of postcataract surgery MO. Cataract formation is common after vitrectomy in diabetic eyes, and risk of postcataract surgery MO is substantial and more likely in eyes with prior CSMO. Cataract formation and risk of postcataract surgery MO should be considered when assessing the long-term benefits of vitrectomy surgery in patients with diabetes.