Purpose
To describe the role of anterior segment Fourier Domain optical coherence tomography (FD-OCT) in limbal epithelial stem cell transplantation.
Methods
Eight eyes of 8 patients undergoing cultivated limbal stem cell transplantation for total limbal stem cell deficiency were included in this prospective, interventional case series. Pre- and peri-operatively, supine FD-OCT scans were performed using an iVue mounted on iStand (Optovue, Germany). The standard pachymetry protocols were repeated more than once and the best quality scans were used to determine corneal pannus and central corneal thickness. Follow-up of central corneal thickness was performed for a mean of 10.6 months (using the RT-Vue (Optovue, Germany) using the same protocol. For corneas with a thickness outside the range of 300 - 800µm, three manual measurements were obtained using the measuring callipers available on the OCT software (iVue software 1.9, RTVue software 5.1, Germany) and the mean of thinnest and thickest zones per scan recorded. The measurements for corneal pannus and epithelium thickness were similarly obtained.
Results
The results of this study indicate that the FD-OCT is an effective tool for obtaining corneal tomography with pachymetry even in highly pathologic corneas with thick fibrovascular panni (Fig 1 and 2A,B). Intra-operatively, the FD-OCT allowed clear visualization of the pannus as an irregular hyperreflective layer (mean thickness: 156 ± 73µm). Blood vessel lumen were visible throughout as well demarcated, circular, hyporeflective regions of varying diameter (Fig 2B). Postoperative images showed presence of the transplanted graft and temporary amniotic membrane patch (Fig 2C). By one month postoperatively, all grafts (n=8) showed integration into the anterior stroma and presence of a 49.6 ± 13µm epithelial layer.
Conclusions
The FD-OCT offers a non-contact method for rapid, high resolution, supine, intraoperative corneal cross sectional imaging with pachymetry mapping. Guided fibrovascular pannus removal could be performed without the danger of intraoperative perforation or induction of ectasia, perforation or wound dehiscence in the early post operative period. The FD-OCT imaging further aided in graft detection and corneal epithelial thickness measurements as well as pachymetry monitoring during post operative follow-up.
Keywords: 721 stem cells •
482 cornea: epithelium •
550 imaging/image analysis: clinical