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Pain responses of Pascal 20 ms multi-spot and 100 ms single-spot panretinal photocoagulation: Manchester Pascal Study, MAPASS report 2
  1. M M K Muqit1,2,
  2. G R Marcellino3,
  3. J C B Gray1,
  4. R McLauchlan1,
  5. D B Henson1,2,
  6. L B Young1,
  7. N Patton1,
  8. S J Charles1,
  9. G S Turner1,
  10. P E Stanga1,2
  1. 1Manchester Royal Eye Hospital, Manchester, UK
  2. 2Faculty of Medicine, University of Manchester, Manchester, UK
  3. 3OptiMedica Corporation, Santa Clara, California, USA
  1. Correspondence to Paulo E Stanga, University of Manchester, Manchester Royal Eye Hospital, Oxford Road, Manchester, M139WL, UK; retinaspecialist{at}


Aims To evaluate pain responses following Pascal 20 ms multi-spot and 100 ms single-spot panretinal photocoagulation (PRP).

Methods Single-centre randomised clinical trial. 40 eyes of 24 patients with treatment-naive proliferative diabetic retinopathy randomised to 20 and 100 ms PRP under topical 0.4% oxybuprocaine. A masked grader used a pain questionnaire within 1 h (numerical pain score (NPS)) and 1 month after treatment (numerical headache score (NHS)). Primary outcome measure was NPS immediately post-PRP. Secondary outcome measures were mean NHS scores and levels of photophobia reported within 4 weeks of primary PRP.

Results Mean laser fluence was significantly lower using 20 ms PRP (4.8 J/cm2) compared to 100 ms PRP (11.8 J/cm2; p<0.001). Mean NPS scores for treatment were 2.4 (2.3) (mild) for 20 ms PRP group compared to 4.9 (3.3) (moderate) in 100 ms PRP group—a significant difference (95% CI 4.3 to 0.68; p=0.006). Mean NHS score within 1 month was 1.5 (2.7) in 20 ms PRP group compared to 3.2 (3.5) in the 100 ms PRP group (p<0.05). The median duration of photophobia after 20 ms PRP was 3 h, and significantly less compared to 100 ms PRP after which 72 h of photophobia was reported (p<0.001).

Conclusions Multi-spot 20 ms PRP was associated with significantly lower levels of anxiety, headache, pain and photophobia compared to 100 ms single-spot PRP treatment. Possible reasons include lower fluence, shorter-pulse duration, and spatial summation of laser nociception with multi-spot Pascal technique.

  • Pascal panretinal photocoagulation
  • pain responses
  • conventional laser
  • proliferative diabetic retinopathy
  • nociception
  • retina
  • treatment lasers
  • clinical trial

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  • This work was presented in May 2009 at the Royal College of Ophthalmologists Annual Congress, Birmingham, UK, and presented in October 2009 at the joint American Academy of Ophthalmology and Pan-American Association of Ophthalmology Annual Meeting.

  • Funding Optimedica Corporation, Santa Barbara, USA.

  • Competing interests GRM is an employee of Optimedica Corporation. PES has received financial support from Optimedica Corporation.

  • Ethics approval This study was conducted with the approval of the Stockport Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.