title: Simulation of panretinal laser photocoagulation using geometric methods for calculating the photocoagulation index.
abstract: OBJECTIVE
  To establish geometrically based methods for simulating panretinal laser photocoagulation (PRP) for the photocoagulation index.
  
  
  METHODS
  A formula for calculating the curved surface area of a spherical dome was used for the simulation. If the radius of the dome is c and the height of the dome is h, then the curved surface area (S) of the dome is S = π (c2 + h2). We calculated the area of the whole retina using this formula and the anatomical dimensions of the standard eyeball. To simulate PRP with a 400-μm spot on the retina with 1-spot spacing, we drew 400-μm-diameter circles, separated by 400 μm, on a retinal map. We calculated the ratio of the total retinal photocoagulated area to the whole retina, termed the photocoagulation index, in order to investigate the impact of the extent of the photocoagulated area and the pulse duration on PRP.
  
  
  RESULTS
  The whole retinal area was 1,092 mm2. The numbers of spots in the scattered and full-scattered PRP were 1,222 and 1,814, respectively. The photocoagulation index was 14.1% and 20.9% for scattered and full-scattered PRP, respectively. These values changed to 14.3% (5.6%) and 21.3% (8.3%), respectively, for PRP with a 100-ms pulse or a 20-ms pulse.
  
  
  CONCLUSIONS
  This method will be useful for investigating the impact of various PRP parameters (duration, spacing, intensity of burns, extent of photocoagulated area, etc.) on the photocoagulation index.
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Sakaguchi
authors.affiliation: Department of Ophthalmology, Aichi Medical University, Nagakute - Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kamei
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Shiraki
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Oura
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Wakabayashi
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Hara
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Fukushima
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Sayanagi
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sato
authors.affiliation: Department of Ophthalmology, NTT Osaka Hospital, Osaka - Japan.
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Suita - Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
mesh_terms: D003930:Diabetic Retinopathy / Q000601:surgery*; D006801:Humans; D007511:Ischemia / Q000601:surgery; D017075:Laser Coagulation / Q000379:methods*; D008962:Models, Theoretical; D012160:Retina / Q000601:surgery*