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Kam-lung, Kelvin Chong, Tiara Iao, Frank Lai, Danny Siu Chun Ng, Joy Leung, Alvin Au, TC Ko, Alvin L Young; Choroidal thickness (CT) in thyroid associated orbitopathy (TAO). Invest. Ophthalmol. Vis. Sci. 2017;58(8):5156. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Subfoveal CT measured by spectral-domain optical coherence tomography (SD-OCT) was recently found to be increased in patients with TAO compared to healthy control and correlated with clinical activity score (CAS) in 2 separate Turkish cohorts. We conducted a prospective observational cross-sectional study to compare different topographic measurements of CT in Chinese patients with TAO and age-matched healthy subjects and to examine if similar correlations were present.
CT was measured with enhanced-depth imaging (EDI) by SD-OCT at the subfoveal, parafoveal (1 and 2 mm from central fovea) and peripapillary regions at each quadrant in TAO (n=104) and controls (n=52) by a masked, experienced operator. Comprehensive ophthalmic examinations including CAS and Hertel exophthalmolmetry were performed by an experienced oculoplastic surgeon unaware of the CT measurements. Generalized estimating equation models were used to compare the CT between eyes with TAO and control, and to evaluate the association of subfoveal CT with demographic and ocular parameters in TAO patients.
Age, gender ratio, intraocular pressure (IOP), axial length (AL) and best-corrected visual acuities (BCVA) were comparable between TAO patients and healthy subjects (all p>0.5). Comparing TAO with control eyes, the CT was significantly increased at subfoveal (p=0.003) and parafoveal regions at 1mm and 2mm from the central fovea of each quadrant (all p<0.05), except 2mm inferior to the central fovea (p=0.164) and each of the peripapillary region (superior, p= 0.238; nasal, p=0.576, inferior, p=0.565; temporal, p=0.104) after adjusting for age, AL, IOP, spherical equivalent and exophthalmometry readings. In multivariate analyses, thinner subfoveal CT was associated with proptosis (p=0.043), poorer BCVA (p=0.017), older age (p=0.04) and longer AL (p<0.001). Neither IOP (p=0.44) or CAS (p=0.1) was found to be significantly associated with the CT in this TAO cohort.
We confirmed the findings of 2 prior studies on the increase in subfoveal CT of TAO patients compared to control while we reported for the first time, similar increase in parafoveal but not in peripapillary CT. Proptosis and poorer BCVA but not CAS was found to be associated with thinner subfoveal CT in this Chinese TAO cohort.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Typical example of a thyroid-associated orbitopathy patient with asymmetric disease. The more proptotic eye showed a thinner subfoveal choroidal thickness.
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