Authors: Daisy Liu
Author Disclosure Block: D. Liu: None.

Abstract Body:

Purpose: To evaluate the incidence and progression of iridociliary cysts presenting to a Canadian tertiary care centre using Ultrasound Biomicroscopy (UBM).

Study Design: Retrospective chart review.

Methods: Charts of patients referred for iris elevation between March 2016 and October 2019 were reviewed. All included patients received a diagnosis of an iridociliary cyst using UBM. Data was collected on age, sex, type (iris versus ciliary body), laterality, size, location in clock hours, and additional features including multicystic or multiloculated cysts on initial appointments and subsequent follow ups.

Results: 154 eyes with iris cysts were seen between March 2016 to October 2019. Of these, more were found in females compared to males (63.8% and 36.2%). The highest incidence of iris cysts occurred in females of 21-30 years of age (17.0%) and in males aged 11-20 (9.2%). 82.2% involved iris pigment epithelium and 14.9% involved the ciliary body. The size of cysts ranged between 0.5-4.41mm in diameter. Cysts larger than 1mm in diameter were more common (78.7%). 90% of cysts occurred unilaterally. 12% were multi-cystic and 8.5% were described as multiloculated and 1% showed both features. All patients were told to follow up in 1 year to reassess. Of the 141 subjects, a total of 30 (21.3%) attended follow up appointments with UBM. 43.3% (13) of iris cysts were stable, with no appreciable change in size, while 16.7% (5) had increased in size and 6.7% (2) saw a reduction in size on UBM. Iris cyst growth was found at 4 months in one patient, while the rest were found in follow up appointments after one or two years. Temporal iris cysts were the most common, consisting of 48.3% and 37.7% in the right and left eyes, respectively.

Conclusions: Evidence for the incidence and risk of progression for iris cysts is scarce. These otherwise benign cysts can grow in size and cause corneal touch and narrowed angles. Given the low rates of progression, the risk of significant growth of iris cysts is rare. Iris cysts likely do not require annual follow up in asymptomatic patients.