Multispectral imaging (MSI) technology, which employs multiple wavelengths from visible to near infrared, has been reported to visualize choroidal fundus. Also, significant choroidal vascularity index (CVI) reduction has been reported in glaucoma and retinitis pigmentosa 9. Diabetic choroidopathy (DC) may induce loss of choriocapillaris (CC), tortuous blood vessels and reduction of blood flow in sub foveal choroidal vasculature 8. For example, AMD may produce choroidal neovascularization (CNV) 7.
In addition to retinal imaging, choroidal imaging can provide a valuable supplement to traditional retinal imaging for better management of choroidal disorders. Because many eye diseases can affect both central and peripheral regions of the retina, a wide-field fundus photography has demonstrated its utility in the clinical management of eye diseases such as diabetic retinopathy (DR) 1, age-related macular degeneration (AMD) 2, glaucoma 3, hypertensive retinopathy 4, retinal detachments 5, and vascular pathologies (vascular occlusions, vasculitis, etc.) 6 with ocular metastasis. In coordination with a fixation target, the FOV can be readily expanded over the equator of the eye to visualize vortex ampullas.įundus photography is indispensable for screening, diagnosis, and management of eye diseases in ophthalmology. Without the need of pharmacological pupillary dilation, a 140° eye-angle field of view (FOV) is demonstrated in a snapshot fundus image. The 780 nm light image enhances the visibility of choroidal vasculature, and the 970 nm image is predominated by large veins in the choroid. The light efficiency-balanced 530 nm and 625 nm illumination control can be used to produce true-color retinal image with contrast enhancement. In comparison with 530 nm illumination, the 625 nm, 780 nm and 970 nm light efficiencies are 30.25, 523.05, and 1238.35 times higher. 530 nm, 625 nm, 780 nm and 970 nm light emission diodes (LED)s are used to quantitatively evaluate the spectral efficiency of the trans-palpebral illumination. This study is to test the feasibility of true-color retinal imaging using efficiency-balanced visible light illumination, and to validate multiple spectral imaging (MSI) of the retina and choroid. Trans-palpebral illumination has been demonstrated for wide-field fundus photography, but its application for true-color retinal imaging is challenging due to the light efficiency delivered through the eyelid and sclera is highly wavelength dependent. A wide-field fundus camera, which can selectively evaluate the retina and choroid, is desirable for better detection and treatment evaluation of eye diseases.
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