Comprehensive retinal safety evaluation of photoacoustic microscopy in rabbits

Abstract

Purpose : To determine whether photoacoustic microscopy (PAM) retinal imaging is safe and whether PAM causes damage to retinal structure or function in rabbit eyes.

Methods : 12 pigmented rabbit eyes received 5 consecutive days of PAM imaging with 5% of the ANSI limit laser energy to achieve high quality PAM imaging of more than 50% of the retinal surface area. One rabbit used for positive control by using 500% of the ANSI limit laser energy. Retinal morphology was examined by ophthalmic examination, fundus photography, red-free photography, fundus autofluorescence (FAF), fluorescein angiography (FA), indocyanine green angiography (ICGA), and optical coherence tomography (OCT). Retinal function was assessed by full field electroretinography (ff-ERGs). Retinal structure was evaluated by histopathology and transmission electron microscopy (TEM). Retinal cells apoptosis was examined by TUNEL assay. Evaluation was performed at 3 days, 1, 2, 3, and 4 weeks post PAM imaging.

Results : Retinal morphologic analyses showed no retinal hemorrhage, edema, detachment, vascular, or pigmentary abnormalities in the retina or choroid after PAM imaging. ff-ERG showed no significant difference in scotopic or photopic a- and b-wave amplitudes or implicit times between the control and experimental eyes. Retinal ultrastructural evaluation using TEM showed normal cellular structure after PAM. TUNEL assay showed no evidence of cells undergoing apoptosis. Retinal histopathology indicated that the architecture and thickness of the retinal layers was well preserved in all experimental eyes. The positive control at 500% of the ANSI limit demonstrated significant damage.

Conclusions : A comprehensive retinal safety evaluation demonstrates no damage to retinal structure or function for 4 weeks after retinal PAM imaging.

This is a 2021 ARVO Annual Meeting abstract.