Corneal Epithelial Thickness Mapping: A Major Review
Sayed mohammadali Abtahi Forushani1 *
- TUMS
Abstract: Te corneal epithelium (CE) is the outermost layer of the cornea with constant turnover, relative stability, remarkable plasticity,
and compensatory properties to mask alterations in the underlying stroma. Te advent of quantitative imaging modalities capable
of producing epithelial thickness mapping (ETM) has made it possible to characterize better the diferent patterns of epithelial
remodeling.
Methods: In this comprehensive synthesis, we reviewed all available data on ETM with diferent methods, including very highfrequency
ultrasound (VHF-US) and spectral-domain optical coherence tomography (SD-OCT) in normal individuals, corneal or
systemic diseases, and corneal surgical scenarios. We excluded OCT studies that manually measured the corneal epithelial
thickness (CET) (e.g., by digital calipers) or the CE (e.g., by confocal scanning or handheld pachymeters). A comparison of
diferent CETmeasuring technologies and devices capable of producing thickness maps is provided. Normative data on CET and
the possible efects of gender, aging, diurnal changes, refraction, and intraocular pressure are discussed.
Results: We also reviewed ETM
data in several corneal disorders, including keratoconus, corneal dystrophies, recurrent epithelial erosion, herpes keratitis,
keratoplasty, bullous keratopathy, carcinoma in situ, pterygium, and limbal stem cell defciency. Te available data on the potential
role of ETM in indicating refractive surgeries, planning the procedure, and assessing postoperative changes are reviewed.
Conclusion: Alterations in ETM in systemic and ocular conditions such as eyelid abnormalities and dry eye disease and the efects of contact
lenses, topical medications, and cataract surgery on the ETM profle are discussed
