Anterior Segment Optical Coherence Tomography: Assisted Topographic Corneal Epithelial Thickness Distribution Imaging of a Keratoconus Patient
We present the case of a 25-year-old male subject, diagnosed with topographic and topometric asymmetrically manifested KCN among his two eyes. Informed consent was obtained from the subject.\nThe right eye (OD) had an uncorrected distance visual acuity of 20/20 and a manifest refraction of plano −0.50 × 170°. Corrected distance visual acuity with this prescription was 20/20+. The left eye (OS), the more symptomatic one, had an uncorrected distance visual acuity of 20/80 and a manifest refraction −7.00 −3.50 × 75°. Corrected distance visual acuity with this prescription was 20/30. The KCN diagnosis was further confirmed by corneal tomography imaging, obtained by WaveLight® OculyzerTM II (Alcon Surgical, Ft. Worth, Tex., USA) which is a Pentacam HR (high-resolution) Scheimpflug imaging camera [2[GA1]]. Examples of anterior corneal surface sagittal curvature maps are shown in fig. for OD and fig. for OS.\nFour consecutive corneal scans in each eye were obtained by AS-OCT RTVue-100 (Optovue Inc., Fremont, Calif., USA), software version A6 (9, 0, 27). Examples of OD and OS epithelial pachymetry maps (6 mm diameter) are provided in fig. , respectively. Repeatability, which can be assessed by the standard deviation of the central epithelium of the 4 scans, was 0.60 and 1.50 μm in OD and OS, respectively.\nAs shown in fig. , OD had a central epithelial thickness (Epi CT) of 52.23 ± 0.60 μm. Overall epithelial thickness (Epi Average) was computed by taking the average of the 17 segment thickness points shown in fig. . The values displayed in each of the 17 segments are the average of the epithelial thickness measurements within each segment. OD had an Epi Average of 51.97 ± 0.70 μm. OS had an Epi CT of 56.75 ± 1.50 μm and an Epi Average of 55.65 ± 1.22 μm.\nThe epithelial topographic thickness variability (Epi Variability, fig. ) was calculated as the standard deviation of the 17 thickness points. Our results show that on average, the Epi Variability was 1.53 ± 0.21 μm for the less affected OD, while it was 9.80 ± 0.41 μm for the more affected OS.