Visualization of Mouse Choroidal and Retinal Vasculature Using Fluorescent Tomato Lectin Perfusion.

Purpose: To develop a reliable and simplified method to assess choroid and retinal vasculature on whole mount and cross sections in mice using tomato lectin (TL; Lycopersicon esculentum). Methods: Albino mice (n = 27) received 1 mg/mL of TL (conjugated to Dylight-594) intravascularly through the tail vein, jugular vein, or cardiac left ventricle. Whole mounts of the retina and choroid were evaluated using fluorescence microscopy. Perfusion with GSL-IB4 conjugated to Dylight-594 and fluorescein isothiocyanate was performed to compare against labeling with TL. Co-labeling of choroidal endothelial cells with perfused TL on cross-sections with antibodies directed against the choriocapillaris-restricted endothelial cell marker CA4 was performed. The percentage of perfused choroidal and retinal vessels was assessed semiquantitatively. One mouse was subjected to thermal laser damage before perfusion to cause retinal and choroidal vasculature ablation. Results: Intravascular injection of TL led to consistent, robust labeling of retinal and choroidal vascular walls. On cross-sections, choriocapillaris was co-labeled with CA4 and TL. On flat mount, TL perfusion resulted in better labeling of choroidal vessels using tail/jugular vein injection compared with cardiac perfusion (P < .01). More consistent labeling of the choroidal and retinal vascular trees was observed with TL than with GSL-IB4. Vascular damage caused by laser ablation was detected readily using this method. Conclusions: TL injection intravascularly can reliably label normal and ablated choroid and retinal vasculature in mouse in a quick, simple manner. Translational Relevance: These data will help to facilitate modeling in rodents for diseases such as age-related macular degeneration, diabetes, and other ischemic/angiogenic processes that can also be used for treatment evaluation.

Correlation of Optical Coherence Tomography and Retinal Histology in Normal and Pro23His Retinal Degeneration Pig.

PURPOSE: We correlate optical coherence tomography (OCT) retinal layer thickness measurements with histology in wild-type and retinal degenerative pigs. METHODS: OCT scans were obtained using the Bioptigen Envisu R2200. In normal pigs, three eyes were imaged in vivo, and three eyes were imaged after enucleation. In the Pro23His retinal degeneration pigs (P23H), one eye was imaged in vivo and four eyes were imaged after enucleation. All eyes were fixed in 4% paraformaldehyde and processed for histology. Corresponding retinal locations on OCT and histology were identified using anatomic landmarks (optic nerve, retinal vessels, visual streak). Individual retinal layer thicknesses were measured by two independent, masked graders, and intraclass correlation coefficients were used to determine agreement. OCT and histologic retinal thickness measurements were averaged and compared. RESULTS: OCT and histologic measurements correlated highly in normal and diseased eyes (R 2 = 0.91 and 0.92, respectively), and scans performed in vivo and ex vivo did not differ significantly. Despite good overall correlation, certain individual retinal layers (e.g., retinal nerve fiber layer [NFL], inner [INL] and outer [ONL] nuclear layers) appeared thicker on OCT compared to histology, while other layers (e.g., retinal pigment epithelium) appeared thinner. No statistically significant difference was found between OCT and histology for any retinal layer thickness measurement. CONCLUSIONS: Retinal layer thickness measurements correlate well with histology in pig eyes, but differences in individual retinal layers may be seen. TRANSLATIONAL RELEVANCE: OCT may be used in pigs to measure retinal thicknesses with good overall correlation to histologic measurements.