Abstract
BackgroundIn the UK, macular laser is the treatment of choice for people with diabetic macular oedema with central retinal subfield thickness (CST) < 400 μm, as per National Institute for Health and Care Excellence guidelines. It remains unclear whether subthreshold micropulse laser is superior and should replace standard threshold laser for the treatment of eligible patients.MethodsDIAMONDS is a pragmatic, multicentre, allocation-concealed, randomised, equivalence, double-masked clinical trial that aims to determine the clinical effectiveness and cost-effectiveness of subthreshold micropulse laser compared with standard threshold laser, for the treatment of diabetic macular oedema with CST < 400 μm. The primary outcome is the mean change in best-corrected visual acuity in the study eye from baseline to month 24 post treatment. Secondary outcomes (at 24 months) include change in binocular best corrected visual acuity; CST; mean deviation of the Humphrey 10–2 visual field; change in percentage of people meeting driving standards; European Quality of Life-5 Dimensions, National Eye Institute Visual Functioning Questionnaire-25 and VisQoL scores; incremental cost per quality-adjusted life year gained; side effects; number of laser treatments and use of additional therapies.The primary statistical analysis will be per protocol rather than intention-to-treat analysis because the latter increases type I error in non-inferiority or equivalence trials. The difference between lasers for change in best-corrected visual acuity (using 95% CI) will be compared to the permitted maximum difference of five Early Treatment Diabetic Retinopathy Study (ETDRS) letters. Linear and logistic regression models will be used to compare outcomes between treatment groups. A Markov-model-based cost-utility analysis will extend beyond the trial period to estimate longer-term cost-effectiveness.DiscussionThis trial will determine the clinical effectiveness and cost-effectiveness of subthreshold micropulse laser, when compared with standard threshold laser, for the treatment of diabetic macular oedema, the main cause of sight loss in people with diabetes mellitus.Trial registrationInternational Standard Randomised Controlled Trials, ISRCTN17742985. Registered on 19 May 2017 (retrospectively registered).
Highlights
In the UK, macular laser is the treatment of choice for people with diabetic macular oedema with central retinal subfield thickness (CST) < 400 μm, as per National Institute for Health and Care Excellence guidelines
The Early Treatment Diabetic Retinopathy Study (ETDRS) showed that macular laser reduced the risk of visual loss in patients with clinically significant diabetic macular oedema (CSMO) by 50% at 3 years [1]
There was no significant difference between ranibizumab and laser in the < 300 μm group, but ranibizumab was much more effective than laser in the > 400 group, in which there was no improvement in best corrected visual acuity (BCVA) with laser
Summary
In the UK, macular laser is the treatment of choice for people with diabetic macular oedema with central retinal subfield thickness (CST) < 400 μm, as per National Institute for Health and Care Excellence guidelines. It remains unclear whether subthreshold micropulse laser is superior and should replace standard threshold laser for the treatment of eligible patients. Diabetic macular oedema (DMO) is a leading cause of blindness in people with diabetes mellitus It represents the accumulation of fluid at the macula, the area of the retina responsible for central vision. More recent trials have shown higher rates of visual improvement (≥ 10 letters in 32% of patients at 2 years and in 44% at 3 years) [2, 3] suggesting that macular laser can improve vision
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