Multimodal imaging of laser-induced choroidal neovascularization in pigmented rabbits

Scientific Reports · 6 authors, 2 centres

AI SUMMARY

FIDELITY 88%

POPULATIONSix Dutch Belted pigmented rabbits (12 eyes) aged 2-4 months, weighing 1.9-3.0 kg

INTERVENTIONLaser photocoagulation at 300 mW, 500 μm spot size, 100 ms pulse duration to induce CNV

COMPARISONNo control group; longitudinal imaging before and after laser treatment

This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.

AGENT 01 · STRUCTURED SUMMARY

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TL;DR

This study successfully induced choroidal neovascularization (CNV) in pigmented rabbits using laser photocoagulation with a 100% success rate, and the CNV remained stable for up to 4 months. Multimodal imaging combining photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescein angiography (FA) allowed precise visualization and differentiation of CNV from surrounding tissues. This rabbit model provides a clinically relevant platform for longitudinal studies of CNV pathogenesis and potential treatments for neovascular age-related macular degeneration.

Full summary

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**Background:** Choroidal neovascularization (CNV) is a key pathological feature of neovascular age-related macular degeneration (AMD), a leading cause of blindness. Animal models are essential for studying CNV pathogenesis and testing therapies. While laser-induced CNV models exist in mice, rats, and primates, no successful laser-induced CNV model in pigmented rabbits had been reported. Rabbit eyes share anatomical and physiological similarities with human eyes, making them valuable for translational research. This study aimed to develop a reliable laser-induced CNV model in pigmented rabbits and evaluate it using multimodal imaging including photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescein angiography (FA).

**Methods:** Six Dutch Belted pigmented rabbits (12 eyes) were treated with 12 laser lesions per eye using a 532 nm Nd:YAG laser at 300 mW power, 500 μm aerial spot size, and 100 ms pulse duration. CNV progression was monitored longitudinally over 120 days using color fundus photography, FA, PAM (at 578 nm and 700 nm with indocyanine green dye), and OCT. Histological and immunohistochemical analysis with hematoxylin and eosin (H&E) and alpha-smooth muscle actin (αSMA) antibody was performed at 120 days.

**Key Results:** All treated eyes developed CNV (100% success rate). FA showed hyperfluorescent leakage at laser sites from day 15 onward, with peak fluorescence intensity at day 0 (114.68 ± 23.96 a.u.) decreasing by 46% at day 15 (53.20 ± 19.74 a.u.) and 21% further by day 120 (42.22 ± 14.38 a.u.). CNV area increased from 1.00 ± 0.29 mm² at day 15 to 2.38 ± 0.60 mm² at day 120. OCT revealed CNV thickness of 89.34 ± 13.53 μm at day 30, increasing by 40% at day 90 (123.44 ± 12.20 μm), and stabilizing at day 120 (131.64 ± 16.36 μm). PAM at 700 nm with ICG dye showed a 59-fold increase in PA signal at day 30 (from background 1.34 ± 0.07 a.u. to 79.25 ± 8.24 a.u., p < 0.01), with no significant change from day 90 to 120. CNV vessel density peaked at 0.75 ± 0.11 cm at day 30 and decreased by 11% at day 120 (0.67 ± 0.15 cm, p > 0.05). Histology confirmed CNV with disruption of Bruch's membrane and neovascularization in the subretinal space, and αSMA staining confirmed smooth muscle cells in vessel walls.

**Clinical Implications:** This study establishes a reproducible, high-success-rate laser-induced CNV model in pigmented rabbits with stable CNV for up to 4 months, enabling long-term evaluation of therapies. Multimodal PAM and OCT imaging provides complementary information: OCT offers anatomical details and CNV thickness, while PAM with ICG dye allows specific visualization of CNV margins and differentiation from surrounding tissues. This model and imaging approach can facilitate translational research on neovascular AMD, including testing anti-VEGF therapies and other treatments.

PICO

PPOPULATION

Six Dutch Belted pigmented rabbits (12 eyes) aged 2-4 months, weighing 1.9-3.0 kg

IINTERVENTION

Laser photocoagulation at 300 mW, 500 μm spot size, 100 ms pulse duration to induce CNV

OOUTCOME

CNV development (100% success rate), CNV area, thickness, fluorescence intensity, PA signal, vessel density, and histological confirmation

STUDY TYPE

other

SPECIALTY

ophthalmology

SUMMARISED BY

AI pipeline

FIDELITY CHECK

88% · B

ORIGINAL PAPER

PMC10209159

Multimodal imaging of laser-induced choroidal neovascularization in pigmented rabbits

Scientific Reports

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ABSTRACT

This study aimed to demonstrate longitudinal multimodal imaging of laser photocoagulation-induced choroidal neovascularization (CNV) in pigmented rabbits. Six Dutch Belted pigmented rabbits were treated with 12 laser lesions in each eye at a power of 300 mW with an aerial diameter spot size of 500 μm and pulse duration of 100 ms. CNV progression was monitored over a period of 4 months using different imaging techniques including color fundus photography, fluorescein angiography (FA), photoacoustic microscopy (PAM), and optical coherence tomography (OCT). All treated eyes developed CNV with a success rate of 100%. The margin and morphology of CNV were detected and rendered in three dimensions using PAM and OCT. The CNV was further distinguished from the surrounding melanin and choroidal vessels using FDA-approved indocyanine green dye-enhanced PAM imaging. By obtaining PAM at 700 nm, the location and density of CNV were identified, and the induced PA signal increased up to 59 times. Immunohistochemistry with smooth muscle alpha-actin (αSMA) antibody confirmed the development of CNV. Laser photocoagulation demonstrates a great method to create CNV in pigmented rabbits. The CNV was stable for up to 4 months, and the CNV area was measured from FA images similar to PAM and OCT results. In addition, this study demonstrates that contrast agent-enhanced PAM imaging allows for precise visualization and evaluation of the formation of new blood vessels in a clinically-relevant animal model of CNV. This laser-induced CNV model can provide a unique technique for longitudinal studies of CNV pathogenesis that can be imaged with multimodal imaging.

CITATION EXPORT

Van Phuc Nguyen, Jessica Henry, Josh Zhe et al.. Multimodal imaging of laser-induced choroidal neovascularization in pigmented rabbits. Scientific Reports. (2023). https://doi.org/10.1038/s41598-023-35394-z

AUTHORS

6 · 2 CENTRES

Van Phuc Nguyen, Jessica Henry, Josh Zhe, Justin Hu, Xueding Wang, Yannis M. Paulus

1grid.214458.e0000000086837370Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105 USA
2grid.214458.e0000000086837370Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48105 USA