Table 4 Previous studies on forme fruste keratoconus (FFKC) with optical coherence tomography (OCT)
From: Early diagnosis of keratoconus using corneal biomechanics and OCT derived technologies
Utilized OCT | Authors | Country | Age (years) | Male (%) | Cases, eyes | Definition of FFKC | Main results | |||
|---|---|---|---|---|---|---|---|---|---|---|
Slit-lamp examination | Topography | Others | Fellow eye | |||||||
RTVue | Pavlatos et al. [100] | US | – | – | 26, 26 | No signs of KC | Normal topography from Scheimpflug or a scanning slit topographer | CDVA of 20/20 or better | Clinical or subclinical KC | Classification accuracy with ectasia index, computed from pachymetry and posterior surface mean curvature, was 63% ± 21% |
Hwang et al. [48] | US | 31.8 ± 13.4 | 57 | 30, 30 | No signs of KC | No definitive abnormalities with Scheimpflug imaging and OCT | CDVA of 20/20 or better | Clinical KC | No individual OCT metric yielded an AUROC > 0.75. Combining 11 OCT thickness metrics ↑ AUROC to 0.96. Combining Scheimpflug/ OCT metrics ↑ AUROC to 1.0 | |
ANTERION | Saad et al. [95] | France | 33.2 ± 7.6 | – | 43, 43 | No signs of KC | No abnormality with specular corneal topography assisted by Nidek Corneal Navigator analysis | CDVA of 20/20 or better | Clinical KC | Among curvature and thickness parameters, I-S value yielded the highest AUROC of 0.850, followed by the magnitude of inferior decentration of posterior steepest keratometry |
CASIA SS-1000/ CASIA2 | Fukuda et al. [101] | Japan | 33.9 ± 14.4 | 76 | 25, 25 | No signs of KC | No topographic signs of KC | Anterior corneal surface curvature metrics of 0% KCI and 0% KSI through the KC screening program involving Placido-disk corneal topography | Clinical KC | Among anterior and posterior keratometric parameters, elevation, topographic parameters, regular and irregular astigmatism and pachymetric parameters, posterior corneal elevation had the highest predictive accuracy (AUROC of 0.912) |
Kitazawa et al. [103] | Japan | 29.5 | 79 | 14, 14 | No signs of KC | Normal anterior topography map by Scheimpflug imaging | – | Unilateral KC | The anterior–posterior ratio of corneal surface area derived from elevation maps yielded AUROC of 0.986 | |
Itoi et al. [102] | Japan | 28.2 ± 6.4 | 85 | 13, 13 | No signs of KC | No topographic signs of KC | TMS-4 keratoconus screening program with 0% KCI | Clinical KC | The anterior–posterior ratio of corneal surface area derived from elevation maps showed AUROC of 0.980 | |
Maeno et al. [99] | Japan | 40.7 ± 9.5 | 68 | 50, 50 | No signs of KC | No topographic signs of KC | Anterior corneal surface curvature metrics of 0% KCI and 0% KSI with the KC screening program involving Placido-disk corneal topography, and the criterion of an I-S value of less than 1.4 D at 6 mm on the topographic map | Clinical KC | In Fourier analysis of corneal power distribution, posterior asymmetry (AUROC 0.778) and higher-order irregularity (AUROC 0.709) showed the best discrimination among single components | |
Shiga et al. [105] | Japan | 22.0 ± 8.5 | 78 | 23, 23 | No signs of KC | No topographic signs of KC | Normal corneal tomography, 0% KCI with Placido-disk corneal topography and 0% diagnosis probability with the ectasia screening score obtained by using AS-OCT | Clinical KC | Combining the Fourier posterior corneal asymmetry and central corneal thickness gave an AUROC of 0.893. Adding SP-A1 from biomechanical assessment \(\uparrow\) AUROC to 0.947, though there was no significant difference between using each device alone or in combination | |