Slit-Lamp-Adapted Fourier-Domain OCT for Anterior and Posterior Segments: Preliminary Results and Comparison to Time-Domain OCT

Abstract

Purpose: To evaluate the diagnostic potential of a slit-lamp (SL)-adapted Fourier-domain (= spectral radar, SR) optical coherence tomography (OCT)—SL-SR-OCT—instrument as an in vivo imaging device for use in examinations of the anterior and posterior segments.

Materials and Methods: In a pilot study, 88 eyes from 70 healthy volunteers and patients were examined using a prototype Fourier-domain SL-SR-OCT system. Results were compared to those from the following commercially available systems: the 1310-nm SL-OCT (Heidelberg Engineering, Heidelberg, Germany) for anterior segment and the Stratus OCT (Zeiss Meditec, Jena, Germany) for posterior segment imaging. Our SL-SR-OCT provides 1025 axial scans, 5000 Hz line-scan frequency, scan length of up to 8 mm, axial depth in air of 3.5 mm, and resolution of 9 μm. For posterior visualization, a hand-held 78-diopter ophthalmoscopic lens was used.

Results: Our SL-SR-OCT system allowed simultaneous scanning with direct biomicroscopic and SL imaging of anterior and posterior segment structures. Anatomical structures and pathological changes were displayed with high resolution and excellent contrast. Measurements of corneal and retinal thickness were possible. In comparison to images obtained by the SL-OCT, our SL-SR-OCT boasted a higher resolution, thus providing more clinically relevant details of the corneal epithelium, internal structure of filtering blebs, etc. Complete imaging of the chamber angle was limited, however, due to the backscattering properties of the sclera at 830 nm. For posterior segment imaging, excellent delineation of the macula and optic nerve head details, with a distinct portrayal of macular pathology and retinal edema, was possible with SL-SR-OCT.

Conclusion: SL-SR-OCT enables detailed imaging of physiological and pathological anterior and posterior segment structures. As a multi-purpose device, it offers a wide spectrum of applications, with high-quality OCT-imaging, in a comfortable setting without the need to move the patient.

KEYWORDS::

• 830 nm
• Fourier-domain OCT
• Slit-lamp adaptation
• Spectral radar OCT
• Time-domain OCT

ACKNOWLEDGMENT

We thank Haag-Streit, Könitz, Switzerland for providing the slit-lamp (and Heidelberg Engineering, Heidelberg, Germany for providing the SL-OCT.)

Declaration of interest: G. Huettmann is a member of the Supervisory Board at Thorlabs HL AG. The authors alone are responsible for the content and writing of the paper.