Abstract
Purpose: :
To correlate intra-retinal in vivo morphologic changes in spectral domain optical coherence tomography (SD OCT) to infrared, fundus photographic and fluorescein angiographic (FA) findings 3 months following panretinal photocoagulation (PRP).
Methods: :
Twelve consecutive patients with proliferative diabetic retinopathy received panretinal laser treatment using the PASCAL© laser system (Optimedica). At month 3, during a same day examination, infrared fundus imaging, color fundus photography, biomicroscopy and fluorescein angiography were performed. Additionally, all patients were scanned using Spectralis© OCT (Heidelberg Engineering©) and results correlated.
Results: :
At month 3, in biomicroscopy all laser burns appeared as clearly demarcated white lesions with distinct borders showing central pigmentation. In infrared imaging, in each laser lesion two characteristic zones could be identified, a central dense, white disc and a surrounding dark halo. In FA, similar patterns were found, i.e. a central dark disc surrounded by a hyperfluorescent ring. In fundus photography again each laser lesion consisted of a central pigmented disc surrounded by a greyish ring. SD OCT revealed these 2 zones to be morphologically different structures. The inner disc was found to be the remnants of coagulated retinal pigment epithelial and photo receptor cells. The surrounding disc was caused by an area of photo receptor atrophy with obviously healthy retinal pigment epithelium. There was a direct correlation between the greatest linear diameter of the atrophic ring and of the coagulated disc.
Conclusions: :
Each retinal laser lesion consists of two morphologic different zones: A central disc of coagulated cell remnants or migrating RPE cells and a surrounding ring of photo receptor atrophy. Even if these characteristics can be visualized with all investigated imaging techniques, only spectral domain OCT revealed the morphologic details causing this characteristic appearance.
Clinical Trial: :
www.clinicaltrials.gov NCT00682240
Keywords: diabetic retinopathy • laser • imaging/image analysis: clinical