Background Recent research on macular disease has prompted investigation into the condition of the intersection of the inner and outer segments (IS/OS) and its relationship with retinal photoreceptor abnormalities. Because the relationship between optical coherence tomography (OCT) images and histopathology is unclear, we compared these in an iodoacetic acid (IAA)-induced model of photoreceptor degeneration in rabbits.

Methods IAA (20 mg/kg), which is toxic to photoreceptors, was injected into six coloured rabbits. After IAA administration, nine retinas were used for histopathological study: three from rabbits surviving for 1 day and six from rabbits surviving for 4 months. Four healthy rabbit retinas served as controls. OCT images were taken before euthanasia.

Results In the controls, OCT images revealed the IS/OS as a clear, straight line. In rabbits surviving for 1 day, the structure of the photoreceptor IS/OS was destroyed and the IS/OS boundary was not visible. In rabbits surviving for 4 months, the IS was still preserved, but the structure of the OS was destroyed or partially disorganised, and the IS/OS was observed as a wavy, broken line on the OCT images.

Conclusion The IS/OS on the OCT images reflected the histopathology of the inner and outer segments in a photoreceptor degeneration model.