Abstract
Purpose :
Although silicone oil 1000 centistokes has been demonstrated to reduce the risk of radiation retinopathy from iodine-125 brachytherapy of uveal melanoma, the feasibility of ultrasonography and measuring tumor thickness in silicone oil filled eyes is unknown. The purpose of this retrospective clinical study was to demonstrate feasibility of ultrasonography in silicone oil filled eyes, and to compare ultrasonographic thickness measurement of uveal melanoma in eyes with (To) and without (T) silicone oil in the vitreous cavity.
Methods :
Sixty-nine uveal melanoma patients who underwent vitrectomy with silicone oil 1000 centistokes placement in the vitreous cavity for radiation attenuation were included. Ultrasonographic thickness measurements in millimeters To and T were performed, either at the time of silicone oil placement or removal from the vitreous cavity. Correlation between To and T was statistically evaluated. Effect of various factors on the strength of correlation was assessed.
Results :
Of 69 patients included in the study, ultrasonographic thickness measurement was feasible at all instances attempted and were recorded at silicone oil placement (before and after oil placement) in 65, and at silicone oil removal (before and after oil removal) in 46 patients. The technique of ultrasonography in silicone oil filled eye is described. In these 111 thickness measurements, thickness (mean ± SD) To was 3.1 ± 1.4 mm, and T was 4.1 ± 2.3 mm. The duration (mean ± SD) between these measurements was 143 ± 115 days. Statistical analysis showed a strong correlation (Pearson correlation coefficient 0.875, p<0.0001) between the two thickness measurements. The relation between the two measurements is given by: To = 0.8 + (0.6*T), with p<0.0001 and R-squared = 0.765 using linear regression analysis. Baseline ultrasonographic tumor thickness had a strong effect, tumor epicenter location had a mild effect, and the duration between two measurements had no effect on the strength of correlation between To and T.
Conclusions :
Obtaining ultrasonographic thickness measurements of uveal melanoma in silicone oil filled eyes was feasible and significantly correlated with tumor thickness obtained without the silicone oil, both before silicone oil placement and after silicone oil removal.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.