Table 1. A comparison of AO-SLO with FAF, FFA, ICGA and OCT.

Methods	Invasive	aTransverse resolution	1,aField angle	First time available	Applications
AO-SLO	2N	2.5 µm	1.5°	2002[12]	Observing cones, rods, vessel and capillary, nerve fiber layer etc (Table 2).
FAF	N	20 µm	50°	31970s[13]	Retinal pseudodrusen, macular edema, choroidal neovascularis[14] choroquine and hydroxychloroquine retinopathy[15] etc.
FFA	Y	20 µm	50°	1960[16]	Fundus neovascularization, aneurysms, tumor, telangiectasis, edema, vitreous inflammation[14] etc.
ICGA	Y	20 µm	50°	1970 in eye[17]	Choroidal vasculopathy, exudative AMD, inflammation and tumors, central serous chorioretinopathy[15] etc.
OCT	N	420 µm	45°	1991[18]	5Vitreoretinal interface disorders, central serous chorioretinopathy, AMD, diabetic retinopathy[15] etc.

¹Pupil diameter at about 6 mm; ²AO-SLO fluorescein angiography not included; ³Fundus autofluorescence was reported around 1870s^[19], but it was not explored for clinical use until 1970s; ⁴Axial resolution is about 5 µm; ⁵AO-OCT and angio-OCT not included; ^aThe approximate data.