title: Photocoagulation in rabbits: optical coherence tomographic lesion classification, wound healing reaction, and retinal temperatures.
abstract: OBJECTIVE
  The rabbit is the most common animal model to study retinal photocoagulation lesions. We present a classification of retinal lesions from rabbits, that is based on optical coherence tomographic (OCT) findings, temperature data, and OCT-follow-up data over 3 months.
  
  
  METHODS
  Four hundred eighty-six photocoagulation lesions (modified Zeiss Visulas® 532 nm CW laser, lesion diameter 133 µm, exposure duration 200  milliseconds or variable, power variable) were analyzed from six eyes of three chinchilla gray rabbits. During the irradiation of each lesion, we used an optoacoustics-based method to measure the retinal temperature profile. Two hours, 1 week, 1 month, and 3 months after the treatment, we obtained fundus color and OCT (Spectralis®) images of each lesion. We classified the lesions according to their OCT morphology and correlated the findings to ophthalmoscopic and OCT lesion diameters, and temperatures.
  
  
  RESULTS
  Besides an undetectable lesion class 0, we discerned subthreshold lesions that were invisible on the fundus but detectable in OCT (classes 1 and 2), very mild lesions that were partly visible on the fundus (class 3), and 3 classes of suprathreshold lesions. OCT greatest linear diameters (GLDs) were larger than ophthalmoscopic lesion diameters, both increased for increasing classes, and GLDs decreased over 3 months within each class. Mean peak end temperatures for 200  milliseconds lesions ranged from 61°C in class 2 to 80°C in class 6.
  
  
  CONCLUSIONS
  The seven step rabbit lesion classifier is distinct from a previously published human lesion classifier. Threshold lesions are generated at comparable temperatures in rabbits and humans, while more intense lesions are created at lower temperatures in rabbits. The OCT lesion classifier could replace routine histology in some studies, and the presented data may be used to estimate lesion end temperatures from OCT images.
authors.affiliation: Department of Ophthalmology, University Hospital of Schleswig-Holstein, Campus Kiel, House 25, Arnold-Heller-Str. 3, 24105, Kiel, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Koinzer
authors.forename: Carola
authors.initials: C
authors.lastname: Hesse
authors.forename: Amke
authors.initials: A
authors.lastname: Caliebe
authors.forename: Mark
authors.initials: M
authors.lastname: Saeger
authors.forename: Alexander
authors.initials: A
authors.lastname: Baade
authors.forename: Kerstin
authors.initials: K
authors.lastname: Schlott
authors.forename: Ralf
authors.initials: R
authors.lastname: Brinkmann
authors.forename: Johann
authors.initials: J
authors.lastname: Roider
mesh_terms: D000818:Animals; D001831:Body Temperature; D005500:Follow-Up Studies; D017075:Laser Coagulation / Q000379:methods*; D023421:Models, Animal; D011817:Rabbits; D012160:Retina / Q000473:pathology / Q000601:surgery*; D041623:Tomography, Optical Coherence; D014945:Wound Healing
keywords: OCT; animal model; laser; laser photocoagulation; optoacoustics; real-time temperature measurement; spectral domain; subthreshold