Fig. 1. System schematic of the TD-OCT system. SLD: super luminescent diode; FOC: fiber optic couplers; PC: polarization modulators; PM: phase modulator; D: detector; DM: demodulator

Fig. 2. HHOCT probes developed by Boppart et al^[39]. (a) The structure of the HHOCT probe; (b) Eye scan using HHOCT probe; (c) Real-time OCT imaging of the cornea

Fig. 3. Two dimensional MEMS scanning mirror^[50]. (a) Layout of the scanning system; (b) Packaged MEMS scanning mirror

Fig. 4. HHOCT probes developed by Lu et al^[42]. (a, b) The probe and its structure; (c) HHOCT imaging of the macula

Fig. 5. Needle-based HHOCT probes. (a-c) 25G needle-based fiber HHOCT probe designed by Joos et al^[57]; (d-f) 23G needle-based fiber HHOCT probe designed by Asami et al^[56]

Fig. 6. OCT-integrated surgical instruments. (a) SMART micro forceps^[58]; (b, c) OCT-integrated micro forceps designed by Yu et al^[61]; (d) Approaching goat retinal using OCT-integrated micro forceps^[61]

Fig. 7. Research-grade MIOCT systems. (a) MIOCT scanner coupled onto the camera port of a microscope^[64]; (b, c) MIOCT integrated prior to the objective^[68]

Fig. 8. Commercialized MIOCT system: Zeiss RESCAN 700. (a) RESCAN 700 system^[3]; (b) Surgeon using RESCAN 700 during ocular surgeries^[69]; (c) Microscope imaging of the RESCAN 700 system^[68]; (d) OCT imaging of the RESCAN 700 system^[71]

Fig. 9. Intrasurgical live 2D imaging with MIOCT. (a) Retinal imaging using single B-scan^[71]; (b) Corneal imaging using two orthogonal B-scans^[73]; (c) Retinal imaging using 5 parallel B-scans^[69]

Fig. 10. Real-time images of anterior segment surgery(canaloplasty) from the microscope-integrated swept-source optical coherence tomography (MIOCT) system^[78]. (a, b) MIOCT image after incision of a superficial scleral flap; (c, d) MIOCT image after insertion of a custom-made trabeculotomy; (e, f) Confirming expansion of the collector vessel using MIOCT image

Fig. 11. Experimental results of ophthalmic surgeries navigated by swept-frequency OCT-based MIOCT. (a) Intraoperative OCT image; (b) Postoperative suture analysis using OCT; (c) Accuracy test results. Trial 1: comparison of the results with (+) and without (-) MIOCT; Trial 2: accuracy of traditional microscope guided surgeries with (+/－) and without (－/－) MIOCT training (* represents statistically significant difference)

Fig. 12. 4D MIOCT real-time imaging. (a) Observing a ceramic ball on the retina^[82]; (b) Real-time image of a surgical tool grasping the retinal pigment epithelial cell layer^[83]; (c) 2D and 3D images of subretinal fluid during vitrectomy^[84]

Fig. 13. HUD-integrated MIOCT for 3D visualization^[79]. (a) HUD-integrated MIOCT in use during a surgery; (b) Real-time image displayed on both oculars

Fig. 14. MIOCT images with enhanced volume rendering^[81]. (a) Original MIOCT image of human eye; (b) Enhanced MIOCT image of human eye; (c) Original MIOCT image of an epiretinal membrane (ERM) and a macular hole (MH); (d) Enhanced MIOCT image of an epiretinal membrane (ERM) and a macular hole (MH)

Fig. 15. Original and colorized MIOCT images of retinal membrane peeling^[87]. (a) Intraoperative MIOCT image; (b) Colorized MIOCT image