Abstract
Purpose :
Recent published evidence suggests that the central retinal thickness in patients with choroideremia (CHM) is initially increased before undergoing slow thinning due to degeneration. We therefore chose to evaluate the early structural changes in young CHM patients with well-preserved fovea and normal visual acuity in more detail by investigating the foveal, choroidal and ellipsoid zone thickness using spectral domain optical coherence tomography (SD-OCT) with comparison made to age and refraction matched normal controls.
Methods :
A single centre retrospective case analysis of OCT from patients with confirmed genetic diagnosis of CHM was conducted at a tertiary eye centre. Data was collected on the above mentioned retinal parameters and compared against data from age and refraction-matched normal controls.
Results :
Twenty-four eyes from 12 male patients (n=24) with early stage CHM were analysed alongside 24 control eyes from 16 normal patients. Mean age at first visit was 21.5 years (Range: 16-40 years), comparable to the mean age of the control group of 23.9 years (Range 16-40 years). The mean refraction was -0.82D in the CHM group (SD: 2.0, SEM: 0.41) and -0.74D in the control group (SD: 1.9, SEM: 0.39). There was no statistical difference between the two groups (p=0.60). The central ellipsoid zone thickness in CHM was reduced in comparison to the control group (mean 68.3 μm in CHM vs. 83.8 μm in control) and the difference was significant (p<0.0001). The central foveal thickness measured at baseline visit was 244 μm (SD 25.3 μm) in CHM compared with 228 μm (SD 14.0 μm) in the control group, which was not statistically significant (p=0.31). There was also no difference found in the choroidal thickness between both groups (234 μm in CHM vs. 235 μm in control, p=0.99).
Conclusions :
Our findings show that there is no difference in the central foveal and choroidal thickness in patients with early stage CHM when compared with age matched controls. However, there is a small but statistically significant reduction in the ellipsoid zone thickness in our small cohort of CHM patients, a finding that warrants further evaluation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.