**7.2 Detection of corneal graft rejection**

Basement membrane thickening has previously been established as evidence of graft rejection in solid organs transplantation [78, 79]. Abou Shousha et al. demonstrated that thickening of the En/DM also occurs in corneal graft rejection (**Figure 6**) [80]. This study was limited by the resolution of HD-OCT as it was not possible to differentiate

#### **Figure 5.**

*A prototypical cross-sectional UHR-OCT image of a human cornea with Fuchs' endothelial dystrophy; sub-epithelial vesicle (red star), Descemet membrane appeared as a thickened band with two opaque lines; the anterior line (yellow arrow) was smooth while the posterior line (white arrow) was wavy and irregular with areas of focal thickening.*

#### **Figure 6.**

*A prototypical cross-sectional UHR-OCT image of a full thickness corneal transplant with active rejection: Descemet membrane appeared as a thickened band with two hyper-reflective lines; the anterior line (yellow arrow) was smooth while the posterior line (white arrow) was wavy, broader with occasional nodular excrescences.*

**13**

*Corneal Microlayer Optical Tomography Review DOI: http://dx.doi.org/10.5772/intechopen.84750*

**7.3. Monitoring surgical patients**

**8. Corneal graft screening**

**9. Future directions**

corneal anatomy and disease.

**10. Conclusions**

and classifications.

**Conflict of interest**

of the En/DM complex in rejected corneal grafts [30].

to predict endothelial cell loss after phacoemulsification [81].

ing results to screen grafts for early endothelial changes [84].

between Descemet membrane, endothelium, and a potential retro-corneal membrane. Subsequent *ex vivo* data revealed that Descemet membrane is responsible for thickening

Transient corneal edema seen after phacoemulsification was caused by changes

Donor tissue quality is critical in the outcome of corneal transplantation [82]. Specular microscopy is the current gold standard for corneal graft screening, but only evaluates the health of the endothelium. We do not currently have an efficient method to screen for epithelial and stromal pathology such as prior refractive surgery, keratoconus or stromal opacities [82]. UHR-OCT can evaluate response to tissue processing in lamellar keratoplasty by revealing interface debris and cavitation bubbles after treatment with femtosecond laser, which may be used to correlate with post-operative outcomes [83]. Our unpublished data demonstrated the use of UHR-OCT to measure the En/DM complex thickness in donor corneas in a sterile container, and has promis-

Future developments include clinical application of the technique to screen donor corneas before transplantation. The newest generation of imaging, micro-OCT (μOCT), uses an isotropic spatial resolution of 1–2 μm. It can detect key cellular and subcellular components such as keratocytes, collagen fibers and corneal nerves. This new technology has the potential to improve our understanding of

UHR-OCT of the anterior segment enables us to perform an optical biopsy of the tear film and all layers in the cornea in normal subjects and those with pathology. These advancements provide understanding about pathological changes in microlayers of the cornea. The main advantages of the OCT include the rapid, non-invasive, in vivo imaging of structures with quantitative measurements. Recent improvements in OCT technology have led to an increase in clinical and research applications. Novel developments, such as the new-generation micro-OCT and artificial intelligence, have the potential to revolutionize corneal disease diagnosis

Vatookarn Roongpoovapatr, Jane Cook and Taher K. Eleiwa—None to declare.

in the central corneal thickness, stroma and En/DM complex. There were no significant post-operative changes in Bowman's layer or epithelium. Pre-operative En/DM thickness may indicate the integrity of the endothelium and could be used between Descemet membrane, endothelium, and a potential retro-corneal membrane. Subsequent *ex vivo* data revealed that Descemet membrane is responsible for thickening of the En/DM complex in rejected corneal grafts [30].
