The purpose of this study is to determine the risk of failing the visual field criteria to hold a driving license following retinal laser treatment delivered with a multi-spot photocoagulator.

Despite improvements in the management of diabetes, the incidence of severe diabetes -related eye disease remains high. Laser treatment (panretinal photocoagulation (PRP)) is the gold standard treatment for reducing the risk of visual loss. However, evidence suggests that PRP can be damaging on visual field function and thus jeopardize patients' eligibility to drive. In the UK, it is the patient's responsibility to inform the DVLA that they are receiving retinal laser.

With the use of a multi-spot Photocoagulator for application of PRP at Moorfields the investigators are in a unique position to assess the effects of laser applied with this new delivery system on visual fields in a detailed fashion. Thus providing more accurate advice on visual prognosis and visual field function and addressing the risk of losing the ability to drive.

All treatment-naive patients with severe diabetic retinopathy requiring bilateral retinal laser treatment will be identified. Following informed consent these patients will undergo baseline visual field testing which will be of a duration of approximately 30 minutes and complete a quality of life questionnaire. All patients will receive their laser treatment as part of standard clinical care via the multi-spot Photocoagulator which will require approximately four 20 minute sessions. At 6 months following the completion of treatment the patients will undergo repeat visual field testing as conducted at baseline and complete a quality of life questionnaire. The investigators hope to recruit 100 patients.

Analysis of visual fields will principally involve assessment of whether patients have met the UK driving standards on Estermann VF testing. A quantitative assessment of change in retinal sensitivity will be undertaken by comparing retinal sensitivity pre and post-PRP.

Inclusion Criteria:

• Patients of either sex aged 18 years or over.
• Diabetes mellitus (type 1 or type 2).
• Best corrected visual acuity (BCVA) > or equal 6/60 in both eyes.
• Requiring full bilateral PRP.
• No previous laser treatment.
• Subject cooperation sufficient for adequate visual field testing.
• Ability to return for regular study visits.

Exclusion Criteria:

• Co-existent ocular/systemic condition that may affect visual field.
• Visual acuity less than 6/60 that may affect accuracy of visual field test.
• Presence of vitreous haemorrhage.
• Intraocular surgery/other intervention anticipated in either eye during the duration of treatment and VF assessment.
• Previous PRP.
• Age below 18.