Table 1.

Comparisons of current PA imaging modalities of the eye. NIR: near infrared, PAM: photoacoustic microscopy, PAOM: photoacoustic ophthalmoscopy.

Specification	PAT	PAOM	Vevo LAZR	REFERENCE
Axial Resolution	~15 μm	~15–37 μm	44–75 μm	[23,38-41]
Lateral Resolution	~45 μm	4.1 μm		[19,39,42,43]
Acquisition Time	>10 min	~2.7 s (2 × 2 mm2)–60 s (3 × 3 mm2)	74 s (10 mm)	[27,42,44]
Imaging Depth	~ 5 cm	~1–3 mm	~2 cm	[23]
Field of view (FOV)	30 × 30 mm	<10 × 10 mm2	~14–23 mm wide	[27]
Application	Anterior of the eye: whole eye tissues	Anterior and posterior of the eyes: retinal vessels, choroidal vessels, and capillaries	Anterior of the eye, SO2	[22,34,41]
Wavelength	532, NIR window	405–2100 nm	680–970 nm	[20,38,42]
Transducer	Single element, Linear Arrays, and planar	Single element	Linear Arrays, and planar	[16,18-21,27,38,41]
Coupling media	Ultrasound gel	Ultrasound gel, water, BSS	Ultrasound gel	[23,25,39,42]
Image acquisition Mode	PAT and US	PAM	PAT, US, and Pulse Doppler	[23,38,39,41]