Evaluating Spectral and Geometric Characteristics of Choroidal Nevi through Multispectral Fundus Photography with Trans-Palpebral Illumination

Abstract

Purpose : To investigate the spectral characteristics of choroidal nevi and evaluate the feasibility of quantifying the basal diameter of these nevi using multispectral fundus images captured with trans-palpebral illumination.

Methods : The study employed a widefield fundus camera featuring multispectral trans-palpebral illumination at wavelengths 625 nm, 780 nm, 850 nm, and 970 nm. Geometric features of choroidal nevi, including border clarity, overlying drusen, and lesion basal diameter, were characterized with multispectral fundus images. Clinical imaging modalities, including scanning laser ophthalmoscopy (SLO), autofluorescence (AF), and optical coherence tomography (OCT), were incorporated for comparative analysis.

Results : Multispectral Fundus images captured with trans-palpebral illumination depicted nevi as dark regions with high contrast against the background (Fig. 1). Lesion-background contrast measurements revealed 635 nm SLO (Fig. 1D2) at 11% and 625 nm fundus at 42% (Fig. 1C1). Significantly enhanced contrasts were observed in near infrared (NIR) fundus images at 780 nm (73%), 850 nm (63%), and 970 nm (67%) (Fig. 1C2-C4). For quantitative measurement of nevus basal diameter, the NIR fundus images at 780 nm and 850 nm yielded a deviation of less than 10%, compared to OCT B-scan measurements (Fig. 2).

Conclusions : NIR fundus photography with trans-palpebral illumination enhances the visibility and boundary definition of nevi compared to SLO. The agreement between the measurements of basal diameter of nevi in the NIR fundus image and OCT B-scan confirms the accuracy and reliability of widefield NIR trans-palpebral illumination for measurement of choroidal nevi.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Fig. 1. Representative images of a choroidal nevus, A1) SLO image, A2) enlarged nevus region. Multispectral fundus images at B1) 625 nm, B2) 780 nm, B3) 850 nm, B4) 970 nm trans-palpebral illumination. C) Enlarged nevus in fundus images at C1) 625 nm, C2) 780 nm, C3) 850 nm, C4) 970 nm. Enlarged nevus in D1) green and D2) red channels of SLO, D3) AF, and D4) NIR reflectance images.

 

Fig. 2. (A) The intensity profile of the nevus in the fundus images along the green dashed line in Fig. 1(C1), (B) Nevus intensity in green and red channels of SLO, AF, and NIR reflectance images, (C) Nevus OCT B-scan.