Purpose: To investigate the optical density (OD) characteristics and clinical relevance of subretinal fluid in choroidal melanoma and choroidal metastasis.
Methods: Medical records of patients with choroidal melanoma and choroidal metastasis who underwent optical coherence tomography examinations at diagnosis before any intervention and whose optical coherence tomography scans showed sufficient subretinal fluid for sampling were reviewed. The highest quality B-scan containing subretinal fluid was analyzed. Optical density measurements obtained using ImageJ and optical density ratios (ODRs) were calculated as subretinal fluid OD divided by vitreous OD. Patient details and diagnosis were masked during measurements. Nonparametric tests for independent samples were used to detect differences in ODR between groups.
Results: Of the 39 cases of choroidal tumors that met the inclusion criteria, 14 were diagnosed as metastases and 25 as malignant melanoma. There were no significant differences between the groups in age, optical coherence tomography acquisition and parameters of quality, and vitreous OD. Optical density ratio values were significantly lower in metastases cases (mean 0.68, SD ±0.18) than in melanoma cases (0.95 ± 0.33, P = 0.006). Receiver operating characteristic curve analysis yielded an optimal cutoff of ODR = 0.771 (sensitivity = 78.6%, specificity = 72.0%).
Conclusion: Optical density ratio can serve as an additional test to differentiate between choroidal melanoma and choroidal metastases.