The impact of pulse duration and burn grade on size of retinal photocoagulation lesion: implications for pattern density

The impact of pulse duration and burn grade on size of retinal photocoagulation lesion: implications for pattern density

Author Palanker, Daniel Google Scholar
Lavinsky, Daniel Autor UNIFESP Google Scholar
Blumenkranz, Mark Scott Google Scholar
Marcellino, George Google Scholar
Institution Stanford Univ
Universidade Federal de São Paulo (UNIFESP)
OptiMedica Corp
Abstract Purpose: Shorter pulses used in pattern scanning photocoagulation (10-20 milliseconds [ms]) tend to produce lighter and smaller lesions than the Early Treatment Diabetic Retinopathy Study standard 100-ms exposures. Smaller lesions result in fewer complications but may potentially reduce clinical efficacy. It is worthwhile to reevaluate existing standards for the number and size of lesions needed.Methods: The width of the coagulated zone in patients undergoing retinal photocoagulation was measured using optical coherence tomography. Lesions of moderate, light, and barely visible clinical grades were compared for 100, 200, and 400 mu m spot sizes and pulse durations of 20 ms and 100 ms.Results: To maintain the same total area as in 1,000 standard burns (100 ms, moderate) with a 400-mu m beam, a larger number of 20-ms lesions are required: 1,464, 1,979, and 3,520 for moderate, light, and barely visible grades, respectively. Because of stronger relative effect of heat diffusion with a smaller beam, with 200 mu m this ratio increases: 1,932, 2,783, and 5,017 lesions of 20 ms with moderate, light, and barely visible grades correspond to the area of 1,000 standard burns.Conclusion: A simple formula is derived for calculation of the required spot spacing in the laser pattern for panretinal photocoagulation with various laser parameters to maintain the same total coagulated area. RETINA 31: 1664-1669, 2011
Keywords laser
photocoagulation
diabetic retinopathy
panretinal photocoagulation
macular grid
Language English
Sponsor Alcon Research Institute
Horngren Foundation
Miller Family Foundation
Angelos and Penelope Dellaporta Research Fund
Date 2011-09-01
Published in Retina-the Journal Of Retinal And Vitreous Diseases. Philadelphia: Lippincott Williams & Wilkins, v. 31, n. 8, p. 1664-1669, 2011.
ISSN 0275-004X (Sherpa/Romeo, impact factor)
Publisher Lippincott Williams & Wilkins
Extent 1664-1669
Origin http://dx.doi.org/10.1097/IAE.0b013e3182115679
Access rights Closed access
Type Article
Web of Science ID WOS:000294456100027
URI http://repositorio.unifesp.br/11600/45220

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