Review Article

Corneal Epithelial Thickness Mapping: A Major Review

Table 2

Studies on the repeatability of different devices in eyes with different conditions.

Author/yearDevice type/brandNo. of subjectsSignificant findings

Studies on normal eyes only
Shen et al. 2013 [56]RTVue (SD-OCT) and CB-OCT (UHR-OCT)NL: 18ICC:
CB-OCT: 0.82–0.97
RTVue: 0.78–0.92
(Higher repeatability toward the center)
Kanellopoulos and Asimellis 2013 [57]RTVue (SD-OCT)NL: 373SW: 0.88 ± 0.71 μm in the center
Wasielica-Poslednik et al. 2015 [58]RTVue (SD-OCT)NL: 23ICC: 0.780–0.952
Beer et al. 2018 [59]CB PS-OCTNL: 20WCV ≤3%
(Very good repeatability)
Hashmani et al. 2022 [60]RTVue (SD-OCT)NL: 220ICC:
Inner circle: 0.703–0.812
Middle circle: 0.712–0.917
Outer circle: 0.796–0.930
(Good-to-excellent reproducibility)
Sikorski 2022 [48]REVO NX, Optopol (SD-OCT)NL: 137ICC: 0.64–0.95
(Higher repeatability toward the center)

Studies on post-LRS eyes ± normal eyes
Reinstein et al. 2010 [23]Artemis VHF-USPost-LASIK: 10SW:
0.58 μm at the corneal vertex
0.43–1.36 μm at the central 6 mm
Ge et al. 2013 [41]RTVue (SD-OCT), Visante (TD-OCT), and 2 CB-OCT devices (UHR-OCT and UL-OCT)NL: 20
Post-LASIK: 18
ICC: >0.84
SW:
<2.2 μm in NL
<4.8 μm in post-LASIK
(Higher optical resolution ∼ better repeatability)
Ma et al. 2013 [61]RTVue (SD-OCT)NL: 35
Post-LASIK: 45
ICC:
≥0.917 in normal
≥0.891 in post-LASIK
Ryu et al. 2017 [62]RTVue (SD-OCT)Post-FS-LASIK: 62
Post-SMILE: 113
SW:
0.8 μm at center
1.2–1.5 μm at midperiphery
(Higher repeatability toward the center)
Sedaghat et al. 2018 [63]RTVue (SD-OCT)Pre and post-PRK: 52SW:
1.73 μm pre-PRK
4.50 μm 6 months post-PRK
Latifi and Mohammadi 2020 [52]RTVue (SD-OCT) (6 mm vs. 9 mm scan)Myopic: 95
Post-PRK: 117
WCV:
In 6 mm scan:
<3.08% (myopic) and <4.80% (post-PRK)
In 9 mm scan:
<5.14% (myopic) and <5.18% (post-PRK)

Studies on eyes with ocular surface disorders ± post-LRS or normal eyes
Li et al. 2012 [7]RTVue (SD-OCT)NL: 75
KCN: 35
SW:
0.7 μm in NL
1.0 μm in KCN (at central 2 mm)
Kanellopoulos and Asimellis 2014 [64]RTVue (SD-OCT)NL: 160
KCN: 160
SW:
0.89 μm in NL
1.78 μm in KCN (at central 2 mm)
Ma et al. 2018 [65]RTVue-XR (SD-OCT)NL: 12
CL user: 12
DED: 11
Post-PRK/LASIK: 12
KCN: 14
SW:
≤2.6 μm in all groups
0.7–1.5 μm in NL
1.0–2.6 μm in CL users
0.9–2.0 μm in DED
0.7–2.5 μm in post-PRK/LASIK
1.1–2.3 μm in KCN (highest in inferior peripheral zones, except for KCN eyes)
Sella et al. 2018 [66]RTVue (SD-OCT)NL: 12
CL user: 12
DED: 12
Post-LRS: 12
KCN: 12
SW:
0.9 μm in NL
1.2 μm in eye with corneal conditions (at central 2 mm)
Similar repeatability in all groups, except DED eyes with lower repeatability (2.0 and 2.4 μm in superior and inferior 2–5 mm ring for DED vs. 0.8–1.3 and 0.8–1.1 μm for other groups); an inverse correlation with DED severity was suggested
Vega-Estrada et al. 2019 [46]MS-39NL: 60
KCN: 107
SW:
1.24 μm in NL
2.03 μm in KCN (at central 3 mm)
Lu et al. 2019 [67]RTVue-XR (SD-OCT)NL (myopic): 75
Post-PRK: 68
Post-SMILE: 61
Post-LASIK: 75
Mild KCN: 20
Advanced KCN: 53
WCV:
1.7–3.5% in NL (myopic)
2.3–6.3% in post-LRS
2.5–6.2% in mild KCN
3.5–8.0% in advanced KCN
(More variable in post-LRS and KCN eyes)
Mohr et al. 2020 [68]RTVue-XR (SD-OCT)KCN: 59
PMD: 10
ICC:
0.827–0.986 in KCN
0.753–0.998 in PMD
(Reduced repeatability toward the periphery)
Li et al. 2021 [69]REVO NX, Optopol SD-OCTKCN ± CXL: 212ICC:
>0.86 in KCN/CXL−
>0.83 in KCN/CXL+
Schiano-Lomoriello et al. 2022 [70]MS 39 SD-OCTKCN: 44WCV < 5% (for central CET)
Feng et al. 2022 [43]Anterion SS-OCT and Avanti SD-OCTNL: 90
KCN: 122
Post-LRS: 46
SW:
By Anterion:
0.88 (NL), 1.08 (post-LRS), 1.26 (KCN) μm
By Avanti:
1.12 (NL), 1.62 (post-LRS), 1.52 (KCN) μm
(In 0–7 mm area)
(Anterion was superior)

CB: custom-built, CL: contact lens, CXL: collagen cross-linking, DED: dry eye disease, FS: femtosecond, ICC: intraclass correlation coefficient, KCN: keratoconus, LASIK: laser-assisted in situ keratomileusis, LRS: laser refractive surgery, NL: normal, OCT: optical coherence tomography, PMD: pellucid marginal degeneration, post: postoperative, pre: preoperative, PRK: photorefractive keratectomy, PS-OCT: polarization sensitive OCT, SD: spectral domain, SMILE: small incision lenticule extraction, SS: swept source, SW: within-subject standard error, UHR-OCT: ultra-high resolution OCT, UL-OCT: ultra-long OCT, VHF-US: very high-frequency ultrasound, and WCV: within-subject coefficient of variation.