Optical Coherence Tomography of Pigmented Choroidal Lesions Using 1060 nm Wavelength

Abstract

Introduction: : Optical Coherence Tomography of Pigmented Choroidal Lesions using 1060 nm wavelength

Purpose: : To investigate optical coherence tomography (OCT) findings of pigmented choroidal lesions with a 1060 nm prototype spectral domain OCT device.

Methods: : 9 eyes of 9 patients with pigmented choroidal lesions were imaged using conventional spectral domain OCT (Cirrus OCT, Carl Zeiss Meditec, Inc.). Additionally, an experimental OCT device with a wavelength of 1060 nm was used to investigate effects of enhanced depth of penetration on the visualization of choroidal lesions. Volumetric data sets with a sampling of 512 x 128 x 1024 voxels at ~5 µm axial resolution and 27.000 depth scans (830 nm) and 512 x 512 x 512 voxels at ~8 µm axial resolution and 47.000 depth scans per second (1060 nm) were acquired across a 20° or 36° scanning angle.

Results: : Choroidal pigmented lesions that were imaged included choroidal nevi and suspected choroidal melanomas. All those lesions could be imaged in full lateral extension. 1060 nm OCT enables greater penetration of depth, but the scleral border could not be captured in all lesions. Disruption of the retinal pigment epithelium and adjacent photoreceptor band can be seen over some lesions. Enhanced depth penetration across a critically sampled three-dimensional scan into the choroid enhances the recognition of the extension of tumor lesions and its margins. Particularly small choroidal lesions can be imaged in full depth. Furthermore, in the marginal regions of the lesions choroidal structures can be seen in greater detail due to the denser sampling. Integrated high resolution data sets, the most similar processing protocol to the 830 nm device, further improve the visibility of deeper and finer structures.

Conclusions: : 1060 nm OCT imaging demonstrated greater depth penetration into the normal and pathological choroid than at 830 nm. Higher scattering of nevus melanocytes in some choroidal lesions prevents full depth penetration to the choroidal-scleral interface. However, compared to conventional OCT additional information such as depth extension can be obtained under similar imaging conditions. This information might be helpful in documentation and follow-up of pigmented choroidal lesions suspected of growth and potential malignant transformation at an earlier stage than with current technology.

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