Methods

We conducted a retrospective chart review of all patients with ciliary body tumors who were followed up at the Princess Margaret Hospital, Toronto, Canada, between April 1990 and December 2008. All patients with ciliary body tumors of a size within the penetration power of the ultrasound biomicroscope (less than 4 mm) were included in the study.

Cases were evaluated for the presence of sentinel vessels, tumor extension to the anterior chamber or iris, cataract, increased intraocular pressure induced by the tumor, and associated ocular inflammation. Any treatment instituted was documented.

UBM was performed as previously described. The commercial version of the ultrasound biomicroscope with a 50-MHz transducer was used (Humphrey Instruments, San Leandro, California, USA). Radial sections through the greatest thickness of the tumor were obtained using an eye cup with 1% methyl cellulose. Tumors were considered as primarily ciliary body in origin when most of the tumor mass was in the ciliary body region ( Figure 1 ). Tumors with most of the lesion in the iris or choroid were considered primary iris or choroidal tumors, respectively, and were excluded. Height was measured from the internal surface of the sclera to the tumor surface at the thickest portion of the tumor ( Figure 2 ). The primary outcome measure was tumor growth, which was defined as an increase in tumor height of at least 20% from baseline, as measured on 2 consecutive UBM readings. For those receiving treatment, tumor size was evaluated until the time of treatment. Intraobserver and interobserver variability in the reproducibility of UBM measurements can be a factor depending on the definition of the structure measured and the experience of the ultrasonographer. A rate of 20% on 2 consecutive UBM measurements was chosen as a definition for growth to minimize any uncertainty resulting from measurement variability.

(Left) Ultrasound biomicroscopy image of a ciliary body tumor (CBT) with extension into the iris. S = sclera; I = iris; C = cornea. (Right) Clinical photograph of same ciliary body tumor extending into the anterior chamber.

Ultrasound biomicroscopy image of a ciliary body tumor with height measured from the internal surface of the sclera to the tumor surface at the thickest portion of the tumor (arrows).

UBM characteristics, including the internal reflectivity, the internal structure, and features such as hyperechoic and hypoechoic patterns, the presence of cystic spaces, and the outer contour of the tumor, were characterized. Iris extension and anterior extension of the tumor relative to the scleral spur also were documented. These features were described in a previous study.

The data were collected longitudinally. The rate of tumor growth was estimated by using mixed model regression accounting for between-individual variation and within-individual variation. The same modeling technique was applied to estimate the rate of tumor growth in the first 3 years and that in subsequent years. The accumulative incidence of tumor growth was estimated by the Kaplan-Meier method where the event was defined as the increase in tumor height of 20% or more from baseline for 2 consecutive measurements. The time to growth was calculated from the start of follow-up to the first date that the growth, as defined earlier, was recorded. Differences between survival curves were analyzed by the log-rank test. A proportional hazard model was applied to assess the effect of continuous variables such as initial tumor height on tumor growth. Results were considered significant if the P value was .05 or less. The statistical analysis was performed using the SAS software version 9.1 (SAS Institute, Cary, North Carolina, USA).

Results

Forty-two patients with ciliary body tumors less than 4 mm in height were included. Clinical data are shown in Table 1 . The median follow-up was 9.0 years (range 1.0 to 17.2 years). The median age was 55.4 years. Twenty patients were male and 22 were female. Twenty-two were right eyes and 20 were left eyes. Other clinical data were available in all but 1 patient. At presentation, 4 patients had evidence of sentinel vessels, 19 patients had a unilateral cataract, and 2 patients had associated ocular inflammation (1 patient had scleritis and another had uveitis). The intraocular pressure was normal in all patients at presentation.

With UBM, the initial median tumor height was 2.05 mm (range 1.11 to 3.80 mm). The overall rate of growth was 0.0014 mm per year ( P = .68). The Kaplan-Meier curve for growth over time is shown in Figure 3 . By 5 years after diagnosis, 5 tumors (12%) demonstrated at least 20% growth from baseline as measured by UBM on 2 consecutive measurements. By 10 years, 9 tumors (29%) grew significantly. Overall, growth in height occurred in 10 tumors. The average time to growth was 5.4 years (range 1.6 to 13.5 years).

Kaplan-Meier curve for accumulative incidence of ciliary body tumor growth over time. Growth in height was demonstrated in a total of 10 tumors. By 5 years after diagnosis, 5 tumors (12%) demonstrated growth. By 10 years after diagnosis, 9 tumors (29%) demonstrated growth.

Smaller tumor height was a significant risk factor for growth ( P = .01). Tumors with an initial thickness less than or equal to 2 mm had a slow but significant rate of growth of 0.0154 mm per year ( P < 0.0001); whereas, tumors with an initial thickness greater than 2 mm showed a small but significant rate of regression of 0.0125 mm per year ( P = 0.04) ( Figure 4 ). Nine of the 19 smaller tumors (47.4%) progressed while only 1 of the 23 larger tumors (4.3%) progressed. However, the rate of growth for the smaller tumors was only significant in the first 3 years after diagnosis (0.054 mm per year; P = 0.0001), after which tumor size appeared to stabilize and the rate of growth was not significant (0.0044 mm per year; P = 0.22) ( Figure 4 ).

Graph showing average height of ciliary body tumors over time. Tumors with an initial thickness less than or equal to 2 mm (n = 19) had a significant but slow rate of growth of 0.0154 mm per year ( P < 0.0001) but size appeared to stabilize after 3 years ( P = 0.22). Tumors with an initial thickness greater than 2 mm (n = 23) showed a small but significant declining trend in growth of 0.0125 mm per year ( P = 0.04).

Ten patients were offered treatment over the course of follow-up ( Table 2 ). Nine patients had a larger initial tumor size (> 2 mm) and one patient had a smaller initial tumor size (≤ 2 mm). The median initial tumor height was significantly larger in patients offered treatment (2.67 mm; range 1.84 to 3.80 mm) versus those not offered treatment (1.91 mm; range 1.11 to 3.80 mm) ( P = 0.008). Four patients were offered treatment due to growth in tumor height. Three patients were offered treatment because of growth in base or a change in shape and volume of the tumor. One patient was offered treatment due to the presence of extrascleral extension on the initial examination. This patient declined and is still being followed almost 18 years after the initial presentation even though the intraocular and extraocular portions of the tumor have consistently grown. Finally, 2 patients were offered treatment before undergoing cataract surgery despite the stable size of the tumor.

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