Choroidal Imaging in Inherited Retinal Disease Using the Technique of Enhanced Depth Imaging Optical Coherence Tomography

Abstract

Purpose: : The aim of this study is to image and describe the in vivo choroidal changes in various retinal dystrophies using the technique of enhanced depth imaging (EDI) optical coherence tomography (OCT).

Methods: : Twenty patients attending the medical retina clinics at Moorfields Eye Hospital (MEH) underwent EDI choroidal scans as part of the scanning protocol when they underwent routine OCT imaging with the Spectralis HRA and OCT. The choroidal images were obtained by moving the Spectralis camera close enough to obtain an inverted image of the retina. The scans were then read by two experienced OCT readers assessing the subfoveal choroidal thickness as well as observing if there were any focal areas of choroidal thinning corresponding to the areas of retinal dystrophy. The spectrum of patients included those with Stargardt Macular dystrophy, macular dystrophies secondary to known mutations such as peripherin/RDS, uncharacterised macular dystrophies, Best vitelliform macular dystrophy, bifocal chorioretinal atrophy, Bietti’s crystalline retinal dystrophy and choroideraemia.

Results: : Twenty patients (38 eyes) underwent choroidal scans using the technique of EDI. The choroidal appearance was symmetrical in all patients who had both eyes scanned. Ten patients showed no choroidal changes, 5 had mild to moderate focal choroidal thinning, 3 had severe focal choroidal thinning, and 2 patients had severe diffuse choroidal thinning.

Conclusions: : The extent and pattern of choroidal thinning is highly variable between patients in the various retinal dystrophies but highly symmetrical between the two eyes in any given patient. Mild focal choroidal thinning may represent choriocapillaris atrophy secondary to retinal pigment epithelial cell death whereas more severe thinning may be due to genetic factors causing atrophy of the larger choroidal vessels.

Keywords: retinal degenerations: hereditary • choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)