Measurement Of Peripapillary Choroidal Thickness In Normal And Glaucomatous Eyes Using Optical Coherence Tomography

Abstract

Purpose: : To measure in-vivo choroidal thickness using spectral domain optical coherence tomography (SD-OCT) in normal eyes, eyes with primary open angle glaucoma (POAG), and eyes with normal tension glaucoma (NTG). It is unclear whether the thickness of the choroid is changed in glaucoma, as previous histological studies have reported both thickening and thinning. It has recently become possible to examine the choroid directly in-vivo through the use of spectral domain optical coherence tomography (SD-OCT).

Methods: : A single eye from 38 healthy participants (mean age 62±9yrs) , 24 individuals with POAG (mean age 62±8) and 16 individuals with NTG (mean age 63±9) was imaged using SD-OCT (Spectralis HRA-OCT; Heidelberg Engineering). A 360º scan approximately 3.45 mm in diameter centered on the optic nerve head was used. Choroidal thickness was measured at 24 discrete points spaced at even 15° intervals across the peripapillary perimeter. These 24 measurements were averaged to produce a mean thickness for each choroid measured. A diagnosis of glaucoma was defined as thinning of the neuroretinal rim (diffuse or focal) and/or a visual field defect as measured using a Humphrey Visual Analyzer (HFA II, Carl Zeiss Meditec) and was defined as early or moderate using a modified Hodapp classification.

Results: : The average thicknesses measured for normal eyes, POAG eyes, and NTG eyes were 121±32 υm, 124±38 υm, and 117±36 υm; there was no significant difference between normal, POAG, and NTG eyes, although there was a trend for the NTG eyes to have the thinnest choroids. The peripapillary choroidal thickness was relatively uniform except for a consistent, abrupt thinning in the inferior quadrant.

Conclusions: : Choroidal thickness does not vary significantly between normal and glaucomatous eyes. The choroid is thinnest in the inferior quadrant in all eyes, a region of interest in early glaucoma.

Keywords: choroid • imaging/image analysis: clinical