Ultrahigh Speed Ophthalmic Surgical OCT for Intraoperative OCT Angiography and Widefield Imaging

Abstract

Purpose : Ultrahigh speed optical coherence tomography (OCT) enables functional imaging such as OCT angiography (OCTA) that require repeated scanning and widefield imaging with densely sampled data sets. We have developed an ultrahigh speed OCT system with a scanner attachment that shares the optical path of a surgical microscope, enabling compatibility among varying microscope models.

Methods : The galvanometer-based OCT module was attached to the Topcon OMS-800 microscope below the objective lens (Fig. 1A). The OCT system uses a 400 kHz, 1050 nm wavelength vertical cavity surface emitting laser (VCSEL) swept source with 80 nm sweep length and ~8 µm axial resolution in tissue. The measured optical power was within the 1.9 mW safety limit. OCTA was performed with 500x500 A-scan, 5 repeated B-scan volumes acquired in 3.6 s. Widefield 1000x1000 A-scan volumes were acquired in 2.9 s. The OCT data was acquired during surgery and reviewed postoperatively.

Results : Fig. 1B-F shows 6x6 mm² OCTA and structural OCT data from an 82-year-old patient during epiretinal membrane surgery. Imaging was performed with an 80D Topcon OFFISS non-contact lens. OCTA was also performed using a GRIESHABER DSP contact lens (Fig. 2A-E). By increasing the scan range, the 80D lens allowed for a 12x12 mm² widefield OCT volume (Fig. 2F-H) of the same patient. The OCT system is capable of assessing anterior ocular structures during cataract surgery of a 72-year-old patient (Fig. 2I-K).

Conclusions : Ultrahigh speed will improve the OCT data quality and bring functional and widefield imaging to the surgical suite. For future work, we will utilize GPU processing for real-time OCT feedback.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Fig. 1 (A) The OCT scanner attachment to the Topcon OMS-800 surgical scope. (B) 6x6 mm² OCTA and (C) structural en-face projections, (D) depth color-encoded flattened 3D rendering, and (E-F) 5 averaged cross sections acquired through an 80D OFFISS lens during epiretinal membrane surgery. Scale bars: 1 mm.

 

Fig. 2 (A) 3.8x3.8 mm² OCTA and (B) structural enface projections, (C) depth color-encoded flattened 3D rendering, and (D-E) cross-sections acquired with a contact lens. (F) Widefield 12x12 mm² structural enface projection and (G-H) cross-sections through an 80D OFFISS lens. (I) Structural enface of the anterior eye with (J-K) cross-sections of the lens capsule. All cross-sections were averaged 5 times. Scale bars: 1 mm.