Choroidal Thickness in Normal Eyes Measured Using Cirrus HD Optical Coherence Tomography

Abstract

PURPOSE To examine choroidal thickness and area in healthy eyes using spectral domain optical coherence tomography (SD-OCT). DESIGN Retrospective, observational case series METHODS Thirty-four eyes (34 subjects), with no retinal or choroidal disease, underwent high definition raster scanning using SD-OCT with frame enhancement software. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500 μm intervals up to 2500 μm temporal and nasal to the fovea. The central 1 mm area of the choroid was also measured, along with foveal thickness of the retina. All measurements were performed by two independent observers. Statistical analysis was used to correlate inter-observer findings, choroidal thickness and area measurements with age, and choroidal thickness with retinal foveal thickness. RESULTS The 34 subjects had a mean age of 51.1 years. Reliable measurements of choroidal thickness were obtainable in 74% of eyes examined. Choroidal thickness and area measurements had strong inter-observer correlation (r =0.92, P < 0.0001) and (r =0.93, P < 0.0001) respectively. Area had a moderate negative correlation with age (r =-0.62, P < 0.0001) that was comparable to the correlation between mean subfoveal choroidal thickness and age (r =-0.61, P < 0.0001). Retinal and choroidal thickness were found to be poorly correlated (r =-0.23, P = 0.18). Mean choroidal thickness showed a pattern of thinnest choroid nasally, thickening in the subfoveal region, and then thinning again temporally. Mean subfoveal choroidal thickness was found to be 272 μm (SD, +/- 81 μm). CONCLUSIONS Choroidal thickness can be measured using SD-OCT high definition raster scans in the majority of eyes. Choroidal thickness across the macula demonstrates a thin choroid nasally, thickest choroid sub-foveally, and again thinner temporally, and a trend toward decreasing choroidal thickness with age.