Patients treated with multispot laser panretinal photocoagulation (PRP) for proliferative diabetic retinopathy can see well enough to pass driving tests, researchers said.
âThis study demonstrates that at six months after bilateral PRP delivered using a multispot laser, a visual field compatible with driving in the UK is preserved in most patients,â wrote Mala Subash, BM, FRCOphth, of the National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital in London, England, and colleagues.
The finding, published in JAMA Ophthalmology, could indicate a safer alternative to conventional single-spot photocoagulation, the researchers said.
Panretinal photocoagulation has been the standard treatment for proliferative diabetic retinopathy since 1975, they wrote.
Single-spot lasers used in photocoagulation usually deliver about 100 milliseconds of laser energy in a single burn. Although effective, they can cause peripheral visual field loss affecting the patientâs ability to drive. The authors cited estimates that within 6 months of treatment, 11% to 50% of patients suffer visual field defects sufficient to stop them from driving.
By contrast, multispot laser panretinal photocoagulation delivers its energy in pulses lasting 20 to 50 milliseconds, combined with a rapid raster scan application of multiple spots. With similar power levels and spot sizes, the overall fluence (power multiplied by time and divided by area) is reduced, the researchers said.
In theory, this could limit collateral retinal damage and reduce the subsequent expansion in laser spot size. The researchers wanted to know whether these lasers have a different effect on the visual field than single-spot lasers.
They recruited 43 patients to participate in a study of a multi-spot laser from June 27, 2012 through October 14, 2013. They excluded everyone with coexistent ocular or systemic conditions that might have affected their visual field, those with a visual acuity of less than 20/200 that might affect the accuracy of visual field testing, and those with vitreous haemorrhages or planned intraocular surgery.