Predictive factors and tumour dynamics in choroidal osteoma: A multimodal imaging-based longitudinal analysis.

Purpose: To evaluate longitudinal multimodal imaging changes in choroidal osteoma (CO) and analyse factors predisposing to sequelae.

Design: Retrospective, observational study PARTICIPANTS: Patients with a diagnosis of choroidal osteoma.

Methods: Baseline clinical characteristics and age-wise distribution of various multimodal imaging parameters, like total osteoma area, area of retinal pigment epithelium (RPE) atrophy, and area of de-calcified choroidal atrophy (d-CA), were analysed. Eyes with well-documented longitudinal follow-up were also analysed.

Main outcome measures: Multimodal imaging features of choroidal osteoma in the calcified and de-calcified areas. To identify changes in the CO lesion parameters and factors predisposing to CO sequelae.

Results: The study included 92 eyes of 73 patients (37 males and 36 females) with a mean age of 32±13.6 years. At baseline, uncomplicated CO was noted in 17.4% of eyes, while d-CA was seen in 39.1% of eyes, and RPE atrophy without underlying d-CA in 35.9% of eyes. Choroidal neovascularisation (CNVM) was seen in 47.8% of eyes. Subretinal fluid without CNVM was present in 14 eyes (15.2%). Thirty-five eyes were included for longitudinal analysis. On regression analysis, factors associated with the presence of CNVM at baseline were the presence of d-CA (p=0.04), RPE atrophy (p=0.04), and macular involvement (p=0.001). A higher rate of increase in the d-CA area was associated with a higher total baseline area of the osteoma (p=0.02) and the presence of CNVM (p=0.04). RPE atrophy (p=0.03) was associated with a faster rate of reduction of osteoma thickness. A faster increase in osteoma thickness was associated with subretinal fluid appearance (p=0.04). Three zones could be identified clinically in eyes with d-CA, i.e. a calcified area with no RPE atrophy, a transition zone of calcified area with overlying RPE atrophy, and a d-CA area. Conclusions RPE atrophy and d-CA are clinically important and quantifiable prognostic factors in the natural history of CO lesions. Three different CO subtypes and zones could be identified that had unique clinical significance.