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Stefan O. Koinzer, Susanne Kleemann, Lea Portz, Lars Ptaszynski, Marco Bever, Kerstin Schlott, Ralf Brinkmann, Johann Roider; Clinico-Pathologic Correlation of Photocoagulation Lesions and Wound Healing in Spectral Domain OCT and Histology. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4992.
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© ARVO (1962-2015); The Authors (2016-present)
High resolution tissue imaging such as optical coherence tomography (OCT) has become essential to ophthalmology and is often claimed to display "in vivo histology". However, direct correlation of OCT and histology is of limited access. We compared retinal photocoagulation lesions in OCT and histology.
600 photocoagulation lesions (133 µm, 200 ms), that were 1 hour, 1 week and 4 weeks old, were examined histologically from rabbits. Spectralis OCT® images were obtained at identical timepoints from 155 human lesions (100 µm, 50-200 ms) and from rabbits. Lesions were matched by their appearance and compared.
Due to a thin ganglion layer, rabbit retina is about 50µm thinner than human retina. One hour after photocoagulation, mild lesions became first detectable at the photoreceptor outer segments (POS) in histology, but in the outer nuclear layer (ONL) in OCT. Retinal pigment epithelium (RPE) detachment or full thickness retinal coagulations were noted in both. Retinal thickening and a third nuclear layer at the site of coagulation were specific to histology. After 1 and 4 weeks, both methods detected RPE cell migration or ONL thinning. Fibrotic scarring, however, was clearly visible in specimens, but hardly detectable in OCT.
Both methods have specific artifacts: Histological changes after photocoagulation such as retinal thickening or duplication of the ONL have no correlation in OCT, while scarring of the inner retinal layers is underestimated in OCT. Despite the similar appearance of healthy retina, OCT is not "in vivo histology" of photocoagulation lesions.
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