Choroidal thickness in normal eyes measured using Cirrus HD optical coherence tomography.

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-microm intervals up to 2500 microm 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 2 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 < .0001 and r = 0.93, P < .0001 respectively). Area had a moderate negative correlation with age (r = -0.62, P < .0001) that was comparable to the correlation between mean subfoveal choroidal thickness and age (r = -0.61, P < .0001). Retinal and choroidal thickness were found to be poorly correlated (r = -0.23, P = .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 microm (SD, +/- 81 microm). 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 subfoveally, and again thinner temporally, and a trend toward decreasing choroidal thickness with age.