Role of Optical Coherence Tomography on Corneal Surface Laser Ablation

Abstract

This paper focuses on reviewing the roles of optical coherence tomography (OCT) on corneal surface laser ablation procedures. OCT is an optical imaging modality that uses low-coherence interferometry to provide noninvasive cross-sectional imaging of tissue microstructure in vivo. There are two types of OCTs, each with transverse and axial spatial resolutions of a few micrometers: the time-domain and the fourier-domain OCTs. Both have been increasingly used by refractive surgeons and have specific advantages. Which of the current imaging instruments is a better choice depends on the specific application. In laser in situ keratomileusis (LASIK) and in excimer laser phototherapeutic keratectomy (PTK), OCT can be used to assess corneal characteristics and guide treatment decisions. OCT accurately measures central corneal thickness, evaluates the regularity of LASIK flaps, and quantifies flap and residual stromal bed thickness. When evaluating the ablation depth accuracy by subtracting preoperative from postoperative measurements, OCT pachymetry correlates well with laser ablation settings. In addition, OCT can be used to provide precise information on the morphology and depth of corneal pathologic abnormalities, such as corneal degenerations, dystrophies, and opacities, correlating with histopathologic findings.

Stromal Bed Thickness Measurement During Laser in Situ Keratomileusis Using Intraoperative Optical Coherence Tomography

“…11 Previous studies on agreement between USP and OCT measurements of central corneal thickness have reported thinner readings obtained by OCT compared with USP. USP relies on accurate perpendicular placement of the probe on the cornea to yield reliable measurements, which is based on the examiner's subjective judgment, whereas for OCT imaging, the corneal apical reflection will be an objective indication to ensure correct scanning position.…”

Miniature forward‐imaging B‐scan optical coherence tomography probe to guide real‐time laser ablation

“…After further improvements and testing, this miniature forward-imaging OCT probe may have the potential for guiding laser surgery. Previous studies have shown that real-time OCT imaging of laser ablation is possible through an external imaging system and through large probes [1][2][3][4][5][6][7][8][9], but not with a 0.5 mm diameter handheld probe.…”

“…Optical coherence tomography (OCT) has emerged as an important medical imaging tool to evaluate structures within the eye, skin, heart, larynx, and teeth amongst other biological tissues before and after surgical ablation [1][2][3][4][5][6][7][8][9]. Optical coherence tomography imaging of laser ablation has been previously achieved through an external imaging system and through large probes [1][2][3][4][5][6][7][8][9], but not through a miniature forward-imaging probe 0.5 mm in diameter. Moreover, most studies have used OCT to evaluate the tissue after completion of the laser ablation and not continuously during the actual lasing process.…”

Ultrafast laser ablation and machining large-size structures on porcine bone

“…The advantages of using lasers to produce these holes include the feasibility of incorporating real-time sensing and feedback mechanisms for high accuracy and precision, 3,30 which is critical to applications such as pedicle screw placement. There are several issues in using laser ablation on hard tissue, such as thermal damage to collateral tissue, shallow penetration depth and difficulty in producing large-diameter and deep holes, and time-consuming drilling time.…”