Management of diabetic macular oedema (DMO)
Reviewed by Kurt Spiteri Cornish

The authors present guidelines on current diagnostic and therapeutic procedures in the management of DMO. Fluorescein angiography (FA) and optical coherence tomography (OCT) are recommended before starting treatment to help diagnose and stage DMO, and can be repeated if there is no response, or to monitor patients. Laser still has a role in the treatment of DMO, as shown in Protocol B of the DRCR.net study, which confirms positive effects of focal / grid laser compared to triamcinolone. Subthreshold laser may also achieve good results while minimising the destructive aspects of conventional laser. Anti-VEGF took over as first-line management in DMO based on a number of studies. DRCR.net Protocol I demonstrates the superiority of ranibizumab therapy over prompt laser therapy, causing a paradigm shift in which laser is no longer seen as first-line treatment. RESTORE study was the first to show that ranibizumab alone provides significantly superior benefit (6.1 letter gain versus 0.8) over laser in patients with visual impairment due to DMO. Its extension study shows that only 3.7 and 2.7 re-treatments were needed in the second and third year respectively. Other studies further confirmed this, including the RISE and RIDE studies. Early therapy with ranibizumab is advisable to achieve best visual outcomes. VISTA DME and VIVID DME subsequently showed similar benefit when using aflibercept instead of ranibizumab. DRCR.net Protocol T suggests superiority of aflibercept over ranibizumab in eyes with visual acuity below 69 letters in the first year of treatment. This was not demonstrable in the second year. Steroids have a role in the treatment of DMO by reducing inflammation and VEGF synthesis as well as improving blood-retinal barrier function. Intravitreal implants of dexamethasone (Ozurdex®) and fluocinolone acetonide (Iliuven®) both have shown improvement in visual acuity and central retinal thickness in eyes with DMO. The main side-effects relate to the incidence of cataract and glaucoma in both treatment groups. The authors recommend steroid therapy in patients who have a history of major cardiovascular events (contraindication of anti-VEGF) and non-responders to anti-VEGF. Surgery (vitrectomy with or without membrane peeling) is reserved in eyes where there is anteroposterior traction, or where there is tangential traction and the response to anti-VEGF or steroid implants is incomplete. Further studies are needed to evaluate effectiveness of surgery in eyes with DMO. 

Guidelines for the management of diabetic macular edema by the European Society of Retina Specialists (EURETINA).
Schmidt-Erfurth U, Garcia-Arumi J, Bandello F, et al.
OPHTHALMOLOGICA
2017;237:185-222.