Objective: It is uncertain whether there is an increased retinal vessel density in patients with thyroid-associated ophthalmology (TAO), or if ocular hemodynamic changes are associated with their vision. Many techniques have been applied to analyze ocular hemodynamic changes in TAO patients; however, they suffer from limitations. Optical coherence tomography angiography (OCTA) is more sensitive to hemodynamic changes. We performed OCTA to determine whether there is an increased retinal vessel density in TAO patients, and investigate associations with their vision.
Methods: Twenty TAO patients (right eye) and 20 normal controls (right eye) were recruited for the study. Three-dimensional OCTA images were generated with 6 × 6-mm angiographic OCT scans of the superficial retinal layer (SRL) and deeper retinal layer (DRL) of the macular retina for each eye. We calculated the microvascular (MIR) and macrovascular (MAR) densities and compared MIR, MAR, and total MIR (TMI) density in the healthy control and TAO groups separately. We used the annular partition (C1-C6) and quadrant partition method to analyze retinal vessel density alterations. Correlation analyses were used to examine the association of MIR density and visual acuity.
Results: In the SRL, STMI (superficial TMI) and SMIR (superficial MIR) density increased in the macular area of TAO patients ( P<.05). For the DRL, the density of DMIR (deeper MIR) increased in macular area only ( P<.05). However, with the annular partition method, TAO patients showed significantly increased SMIR density in the C1 and C2 regions ( P<.05), and increased DMIR density only in the C1 region ( P<.05). In the SRL, the correlation coefficient of the STMI/SMIR density in the TAO group was -0.538 ( r = -0.538, P = .032), and visual acuity was -0.624 ( r = -0.624, P = .010).
Conclusion: OCTA findings suggest that active TAO patients present with an increased retinal MIR density. Moreover, increased macular STMI and SMIR density might affect visual acuity.
Abbreviations: CDI = color Doppler imaging; DMIR = deeper MIR; DRL = deeper retinal layer; EDV = end diastolic velocity; FAZ = foveal avascular zone; GO = Graves ophthalmopathy; MAR = macrovascular; MIR = microvascular; OCT = optical coherence tomography; OCTA = optical coherence tomography angiography; RI = resistance index; ROC = receiver operating characteristic; SMIR = superficial MIR; SOV = superior ophthalmic vein; SRL = superficial retinal layer; SSADA = split-spectrum amplitude-decor-relation angiography; STMI = superficial TMI; TAO = thyroid-associated ophthalmology; TMI = total MIR.