The effect of the density and distribution of panretinal photocoagulation (PRP) laser on driving visual fields in people with diabetes

Brief plain language background

Diabetic eye disease is a group of eye problems that can affect people living with diabetes.

People living with diabetic retinopathy – the most common cause of vision loss for people with diabetes – can lose their central vision when abnormal blood vessels grow and leak under the retina, which is the light-sensitive tissue at the back of the eye.

One of the typical treatments for severe levels of diabetic eye disease is panretinal photocoagulation (PRP) laser treatment. Although PRP laser has been shown to halve the risk of severe vision loss and help to stabilise diabetic eye disease in the long term, it causes laser scars that can affect peripheral vision.

What problem/knowledge gap does it help address

Maintaining adequate vision for safe driving is a common concern for people with diabetic eye disease to keep their independence.

The Driver and Vehicle Licensing Agency (DVLA) have a number of eyesight standards needed to hold a driving license, including for peripheral vision. The DVLA requires people who have had PRP laser to undergo visual field testing to confirm whether they meet this standard.

There is great variation in the distribution of scars from PRP laser due to, for instance, the severity of the condition being treated or the time since treatment.

Some evidence shows short-term encouraging results for people with diabetes retaining driving vision after PRP laser treatment; however, the impact of PRP laser scar distribution on this outcome hasn’t been evaluated.

Aim of the project

To generate pilot data on the variation of PRP laser and the impact on driving visual fields and subjective visual function in people with diabetes.

Key procedures/objectives

1. Recruit 74 people with diabetes who had previous symmetrical PRP laser and a post-treatment DVLA driving visual field test.
2. Assign study participants into two groups based on the distribution of PRP laser at the time of the driving visual field test.
3. All study particpants will complete a questionnaire including the outcome of the driving visual field test and the subjective impact of PRP laser on each participants’ visual function.
4. Compare the groups to evaluate whether the distribution of PRP laser correlates with the driving visual field test results and effects on subjective visual function.

Potential impact on people with sight loss

Due to concerns about losing their eligibility to drive, some patients avoid eyecare appointments and PRP treatment, risking severe vision loss. The pilot study and the planned follow-on work aim to provide eye doctors with more specific advice for patients about PRP laser, which has compelling evidence to stablise severe diabetic eye disease and reduce severe vision loss.