The laser therapy is applied via a slit lamp. After topical anaesthetic, a contact lens is placed on the eye and the laser applied.
The argon laser is used in retinal laser treatment, and creates thermal burns in the retinal pigment epithelial layer with secondary effects on the retina.
In cases of focal laser therapy to aid the sealing of leaking vessels, the procedure takes about 10 minutes and is relatively pain free.
If pan-retinal photocoagulation is required – e.g., for a proliferative diabetic retinopathy – the patient will need more than 2,000 burns. This can be painful, and so treatment is usually given over several sittings.
Foveal burn. This is a delicate procedure. If the patient looks into the laser light at the moment the ophthalmologist fires a shot, the patient can sustain a foveal burn with a marked permanent reduction in vision. Thankfully this is exceedingly rare.