A comparison of standard laser with micropulse laser for the treatment of diabetic macular oedema

INTERVENTION: Participants are randomised to one of two groups in a 1:1 ratio by an automated randomisation system to generate the random allocation sequence. Intervention group: Participants undergo treatment with the micropulse laser. This involves the use of a laser technology aimed at minimising damage (“tissue‐sparing”) to choroid and retina but maintaining treatment efficacy by its selective effect on the retinal pigment epithelium (RPE). It is performed using a laser that, instead of delivering a continuous‐wave laser beam, as the standard laser, it provides very small, repetitive, low energy pulses of laser separated by a brief rest period. This rest period allows the tissue to cool down between laser pulses avoiding the increased tissue heat that would be produced by continuous laser and allowing the use of lower laser energy power to achieve an effect. The reduced heat produced in the tissue and the reduced energy power required for the treatment may reduce side effects. Specifically, the technology does not appear to cause retinal burns or scars associated with decreased retinal sensitivity in treated areas. Control group: Participants receive standard treatment. This involves the use of standard threshold laser with any of the devices used currently for this purpose (e.g. frequency‐doubled neodymium‐doped yttrium aluminium garnet (Nd:YAG) 532 nm laser, argon laser, diode [561nm or IQ (577nm)] laser. Standard laser is applied to areas of thickened retina, macular non‐perfusion and leaking microaneurysms, in accordance the modified ETDRS technique. At baseline and again after 4, 8, 12, 16, 20, 24 months, participants undergo an opthamological examination and OCT scan to establish their eligibility for the study and to determine the changes to their eye following laser treatment. Health and vision related quality of life will be evaluated through the use of the EQ‐5D ‐5L, the NEI VFQ‐25 and the VisQoL which will be obtained t baseline and months 12 and 24. CONDITION: Specialty: Ophthalmology, Primary sub‐specialty: Glaucoma; UKCRC code/ Disease: Eye/ Disorders of choroid and retina ; Eye Diseases ; Diabetic Macular Oedema PRIMARY OUTCOME: BCdVA in the study eye is assessed by a BCdVA test (using ETDRS visual acuity charts at 4 meters) at baseline and months 4,8,12,16,20 and 24. INCLUSION CRITERIA: Patients with diabetic retinopathy and centre involving DMO, as determined by using spectral domain optical coherence tomography (SD‐OCT), in one or both eyes with: 1. Central retinal subfield thickness of > 300 but < 400 microns as determined by SD‐OCT due to diabetic macular oedema OR 2. Central retinal subfield thickness of < 300 microns provided that intraretinal and/or subretinal fluid is present in the central subfield (central 1 mm) related to diabetic macular oedema AND 3. Visual acuity of > 24 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (Snellen equivalent > 20/320) 4. Amenable to laser treatment, as judged by the treating ophthalmologist 5. Over 18 years of age SECONDARY OUTCOME: 1. Binocular BCdVA is assessed by a binocular BCdVA test (using ETDRS visual acuity charts at 4 meters) at baseline and 24 months; 2. Central subfield retinal thickness, as determined by spectral domain OCT at baseline and 24 months; 3. Mean deviation (MD) of the Humphrey 10‐2 visual field is assessed by a Humphrey 10‐2 visual field test at baseline, 12 and 24 months; 4. Percentage (%) of people meeting driving standards is assessed by an Esterman binocular visual field test at baseline and 24 months; 5. Visual functioning (NEI VFQ‐25), general health (EQ‐5D‐5L) and vision and quality of life (VisQol) are measured using NEI VFQ25, EQ‐5D 5L and VisQoL questionnaire scores at baseline and 24 months; 6. Incremental cost per quality‐adjusted life year (QALY) gained is assessed by a Markov model based cost‐utility analysis which will extend beyond the trial analysis period to estimate the longer‐term cost‐effectiveness, with costs and benefits discounted at 3.5%. The model will be populated by data from the trial and supplemented by estimates of effectiveness, quality of life and costs from published literature and expert opinion. ; 7. Side effects are measured by a review of the participant’s medical and ophthalmic history at 4, 8, 12, 16, 20, 24 months; 8. Number of laser treatments needed is assessed by the treating ophthalmologist at 4, 8, 12, 16, 20, 24 months; 9. Use of additional treatments (other than laser) is assessed by the treating ophthalmologist at 4, 8, 12, 16, 20, 24 months