Abstract
Purpose: :
To review the benefits, limitations and adverse effects of laser photocoagulation, the standard of care for the treatment of diabetic retinopathy (DR), in comparison with newer laser techniques intended to provide at least the same benefits while reducing the treatment’s hardship and collateral side effects.
Methods: :
Literature review and physical/technical considerations.
Results: :
Retinal photocoagulation is the mainstay of treatment for DR. The effectiveness of panretinal photocoagulation (PRP) in reducing the risk of severe visual loss has been shown in various studies. PRP is a lengthy and painful treatment, completed in multiple sessions, and associated with iatrogenic anatomical and functional damage (i.e. moderate visual loss, field abnormalities, worsen color vision, night driving and dark adaptation). Light panretinal photocoagulation (LPRP) protocols have shown efficacy similar to that of conventional panretinal photocoagulation (CPRP) with lower number of treatment sessions and fewer overall complications. A new semi-automated patterned scanning laser system has been introduced to reduce PRP's application time, patients' pain and, possibly, to complete the treatment in one session. Shorter and more uniform PRPs have been reported, but still with some level of patient discomfort and with retinal anatomical and functional damage inherent to the visible burn endpoint. In contrast, new subthreshold diode-laser micropulse (SDM) clinical protocols have suggested that the benefits of laser therapy can be achieved with very light treatments that are better tolerated by the patients, do not cause iatrogenic functional vision deterioration and leave no sign of laser-induced lesion at any time postoperatively.
Conclusions: :
Retinal destruction has never been demonstrated to be necessary or a prerequisite for the benefits of laser therapy. Whatever the elusive mechanisms of action of laser photocoagulation are, photothermal laser therapy can provide long term benefits either when administered with high intensity/low density protocols with inherent large thermal spread and collateral side effects or with low intensity/high density protocols with negligible thermal spread and no collateral side effects. Non-laser treatments are being tested to treat DR, often with great and rapid, but also only transient effects. The combination of the short term beneficial effects of medical treatments with the long term benefits of a less damaging laser therapy appears as a new treatment paradigm that should undergo rigorous investigation.
Keywords: laser • diabetic retinopathy • retina