Abstract
Purpose: :
To non-invasively investigate the effects of nicotine and early stage diabetes on retinal structure using spectral domain optical coherence tomography in an established rodent model.
Methods: :
Sprague-Dawley rats (n=45) were examined using a combination of confocal scanning laser ophthalmoscopy and spectral domain optical coherence tomography (Spectralis®, Heidelberg Engineering) to determine changes in retinal structure in response to nicotine exposure (initiating at 0.3mg/kg to a final dose of 2.1 mg/kg), diabetes (induced with 60 mg/kg body weight streptozotocin) and the combined effects of nicotine exposure and diabetes. Retinal thickness in superior, inferior, nasal and temporal quadrants were determined based on SD-OCT volume scans (20°x20°) centered on the optic disc. Segmentation of discrete retinal layers was performed on a subset of SD-OCT cross-sections to further examine changes in individual layers from each treatment group.
Results: :
The control group did not experience any significant change throughout the study. The nicotine treatment group experienced an average decrease in total retinal thickness (TRT) of 9.4 µm with the majority of the loss localized within the outer nuclear layer. Although the results were not statistically significant, the diabetic group exhibited a trend toward decreasing TRT. However, segmentation did reveal significant thinning within the ONL of the diabetic group. The combination of nicotine and diabetes revealed a significant increase of 8.9 µm in the TRT.
Conclusions: :
We demonstrated significant changes in retinal morphology in response to nicotine exposure, diabetes and with the combined effects of nicotine and diabetes. These findings may have implications in determining treatment strategies for diabetic smokers.
Keywords: drug toxicity/drug effects • retinal degenerations: cell biology • imaging/image analysis: non-clinical