Assessment of central corneal thickness in normal, keratoconus, and post-laser in situ keratomileusis eyes using Scheimpflug imaging, spectral domain optical coherence tomography, and ultrasound pachymetry.
OBJECTIVE
To compare the central corneal thickness (CCT) in normal eyes, eyes with keratoconus, and eyes after laser in situ keratomileusis (LASIK) using 3 methods.


METHODS
Cornea Clinic, Grewal Eye Institute, Chandigarh, India.


METHODS
In this study, CCT was measured by sequential Scheimpflug imaging, spectral-domain anterior segment optical coherence tomography (AS-OCT), and ultrasound (US) pachymetry.


RESULTS
Each of the 3 groups comprised 50 eyes. There were no differences between the 3 groups in age, sex, or intraocular pressure. In normal eyes, CCT was statistically significantly higher by US pachymetry (mean 525.8 microm +/- 41.4) [SD] than by Scheimpflug imaging (mean 519.4 +/- 40.9 microm) and AS-OCT (mean 517.9 +/- 41.5 microm) (both P<.001). In keratoconus eyes, CCT by US pachymetry (mean 446.4 +/- 57.9 microm) was statistically significantly higher than by Scheimpflug imaging (mean 439.6 +/- 62.1 microm) (P = .002) and AS-OCT (mean 441.8 +/- 58.4 microm) (P = .007). In post-LASIK eyes CCT by US pachymetry (mean 462.4 +/- 44.7 microm) was significantly higher than by Scheimpflug imaging (mean 457.9 +/- 33.6 microm) (P = .012) and AS-OCT (mean 455.4 +/- 43.2 microm) (P<.001). In all groups, CCT measured by Scheimpflug imaging and AS-OCT was similar.


CONCLUSIONS
There was a statistically significant difference between Scheimpflug imaging and US pachymetry and AS-OCT, with US pachymetry measurements being consistently thicker. Thus, CCT should be interpreted in the context of the instrument used.
Grewal
Dilraj S
DS
Grewal Eye Institute, Chandigarh, India. dilraj@gmail.com
Brar
Gagandeep S
GS
Grewal
Satinder P S
SP
D000293:Adolescent; D000328:Adult; D003315:Cornea / Q000033:anatomy & histology* / Q000473:pathology*; D003430:Cross-Sectional Studies; D003952:Diagnostic Imaging / Q000379:methods*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000150:complications*; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D011184:Postoperative Period; D012016:Reference Values; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D055815:Young Adult