Catherine Favard (Paris, France)


The Pattern Scanning Laser (Pascal) is a semi-automatic photocoagulator using short pulses of 10 to 20 milliseconds applied in square (2X2 to 5X5 impacts) or grid (14 to 56 impacts) patterns.


Between March 2008 and May 2010, 27 eyes: 15 Ischemic diabetic retinopathies (DR) and 12 ischemic retinal venous occlusions (RVO) were treated by pan retinal photocoagulation (PRP) and 33 eyes (16 DR et 17 branch RVO) with macular edema (ME) were treated using Pascal laser.  ETDRS visual acuity, macular Spectralis ® OCT (S-OCT) and fluorescein angiography (FA) were performed before and every 3 to 6 months after treatment.

Effectiveness / Safety:

Grid pattern automatic treatment for ME with 10 ms impacts was abandoned at 6 months since it seemed to have minimal effect on ME. Single visible impacts of 20 ms seemed to induce ME regression as efficiently as conventional laser. SD OCT showed grid hyper reflective burns reaching the outer nuclear layer and after 4 to 6 months a decrease in ME confirmed at 12 months follow up. Compared to conventional laser, macular and PRP 20ms burns did not enlarge at 12 months follow-up on FA. One to 3 sessions with Pascal laser compared to 4 to 6 sessions with conventional laser were necessary to achieve complete PRP and regression of new vessels. PRP with Pascal induced pain in 10% compared with 50% of eyes treated with conventional laser.

Take home message:

Compared with conventional laser, Pascal laser treatment for PRP shortens the number and duration of laser sessions. Pascal’s 20 ms impacts decrease pain, and enlargement of laser scars. For macular grid, single impacts of 20 ms appear preferable to achieve a precise efficient and safe treatment of ME, with reduced thermal damage of the outer retina.