How Does Image Testing Help in Ocular Melanoma?
Ocular melanoma requires imaging to aid in diagnosis, to monitor suspicious lesions, and to monitor post-treatment follow-up. Image testing provides critical insights into the tumor’s dimensions, location, and vascularity, which helps guide treatment decisions and track therapeutic outcomes. Various imaging modalities—ultrasonography (both B-scan and ultrasound biomicroscopy, or UBM), color photography, fluorescein angiography, and optical coherence tomography (OCT)—are each uniquely suited to contribute essential information at each stage of ocular melanoma management (Xu et al, Current Opinion in Ophthalmology, 2021).
1. Ultrasonography
B-Scan Ultrasonography
B-scan ultrasonography is an important tool for diagnosing and monitoring ocular melanoma due to its capacity to visualize intraocular structures and assess tumor characteristics. By emitting sound waves, the B-scan provides cross-sectional images that can identify key tumor features, including its size, internal reflectivity, and growth pattern. Studies demonstrate that the distinct appearance of a melanoma on B-scan, such as its low-to-medium internal reflectivity and dome or mushroom shape, supports its differentiation from benign lesions like choroidal nevi. B-scan is especially beneficial for monitoring patients with suspicious nevi, as it can reveal subtle increases in tumor height or shape, which may indicate transformation to malignant melanoma. Consequently, B-scan ultrasonography is fundamental in ocular melanoma management, guiding both diagnosis and surveillance of potentially malignant nevi. (Solnik et al, Cancers (Basel), 2022).
Ultrasound Biomicroscopy (UBM)
UBM, with its higher frequency sound waves, provides enhanced resolution of structures in the front of the eye, which is important when assessing tumors near the iris or ciliary body. UBM enables ophthalmologists to examine the tumor’s anterior extension, shape, and relation to nearby structures with a high degree of precision. It may help distinguish between benign and malignant iris lesions and for tracking changes in small lesions over time. For patients with iris melanoma or suspicious iris nevi, UBM can document tumor characteristics such as thickness and extension into adjacent tissues. (Conway et al, British Journal of Ophthalmology, 2005).
2. Color Photography
Color fundus photography is a straightforward yet important tool in the assessment of ocular melanomas. It allows for non-invasive documentation of tumor color, borders, and any associated features, such as subretinal fluid or orange pigment. In cases of small or suspicious nevi, color photography serves as a baseline for longitudinal monitoring, making it easier to detect changes in size, pigmentation, or other features over. Furthermore, after radiation therapy, color photos help document tumor response to treatment, as well as side-effects to treatment such as radiation retinopathy or optic neuropathy. Research shows the importance of regular color imaging in detecting subtle yet clinically significant changes in lesion appearance that could prompt early intervention or additional treatment (Aronow, Review of Ophthalmology, 2018).
3. Fluorescein Angiography
Fluorescein angiography is instrumental in assessing the vascular properties of ocular melanomas and detecting complications following treatment. By administering fluorescein dye and capturing its flow through retinal vessels, this imaging technique reveals information about the tumor’s blood supply and potential areas of leakage. Malignant melanomas sometimes exhibit abnormal vascular patterns that can distinguish them from benign nevi. Additionally, fluorescein angiography is invaluable in detecting radiation-related complications, such as radiation retinopathy. By identifying and monitoring these features, fluorescein angiography aids in guiding treatments to manage post-radiation complications effectively, such as laser and injections to the eye. (Garcia-Valenzuela, Medscape, 2024).
4. Optical Coherence Tomography (OCT)
OCT has become a critical imaging modality in ocular oncology for assessing the structural details of ocular melanomas, particularly small tumors in the posterior segment. By using light waves to create detailed images of the retina, OCT allows ophthalmologists to assess tumor-induced changes in the retinal architecture and measure associated subretinal fluid. In the context of choroidal nevi, OCT can detect signs of activity, such as increased subretinal fluid or retinal edema, which may indicate transformation into melanoma. OCT is equally beneficial post-treatment, as it helps identify radiation-related side-effects such as cystoid macular edema or atrophy, which can direct treatment. OCT may detect early retinal changes in melanoma patients, which correlates with treatment efficacy and visual prognosis. As a non-invasive, high-resolution technique, OCT complements other imaging modalities, providing a detailed view of retinal layers that informs both diagnosis and follow-up care. (Obuchowska, Cancers (Basel), 2022.)