Participants in this arm will receive Na Fluorescein 10% Inj 3mL (300mg) before taking fluorescein angiography.

Participants in this arm will receive Na Fluorescein 10% Inj 1mL (100mg) before taking fluorescein angiography.

Patients will receive Fluorescein Sodium 3mL (300mg) or 1mL (100mg) intravenously prior to fluorescein angiography.

Images from two dose groups will be compared in terms of central and peripheral image quality. Three retinal experts were masked to the fluorescein dose the patients had received. Each expert graded patients' fluorescein angiography images on a scale of 1 to 5 (1:very poor, 2: poor, 3: average, 4: better than average, 5: excellent) with respect to the subjective quality of the image and aid of making a diagnosis. The mean value of the image quality score will be compared between the two dose groups.

Mean vascular pixel intensity was quantitatively measured using ImageJ (version 1.54f, National Institutes of Health). The 8-bit grayscale image was imported into imageJ and processed with a top-hat filter to suppress the background noise. This UWFA image was divided via a customized grid, consisting of 2 rings centered on the fovea. The mean vascular pixel intensity in each of these zones was then automatically measured using imageJ software.