we have introduced and reported   a potential novel clinical indicator for keratoconus ( kcn ) cornea instability assessment based on consistent , increased overall corneal epithelial thickness .
as in our previous report , most epithelial measurements have been performed in vivo , by high - frequency scanning ultrasound biomicroscopy ( hf - ubm ) .
we report herein similar data using anterior segment optical coherence tomography ( as - oct ) .
we present the case of a 25-year - old male subject , diagnosed with topographic and topometric asymmetrically manifested kcn among his two eyes .
 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
the kcn diagnosis was further confirmed by corneal tomography imaging , obtained by wavelight oculyzer ii ( alcon surgical , ft .
, usa ) which is a pentacam hr ( high - resolution ) scheimpflug imaging camera [ 2[ga1 ] ] .
four consecutive corneal scans in each eye were obtained by as - oct rtvue-100 ( optovue inc . ,
examples of od and os epithelial pachymetry maps ( 6 mm diameter ) are provided in fig .
repeatability , which can be assessed by the standard deviation of the central epithelium of the 4 scans , was 0.60 and 1.50 m in od and os , respectively .
2a , od had a central epithelial thickness ( epi ct ) of 52.23  0.60 m
. overall epithelial thickness ( epi average ) was computed by taking the average of the 17 segment thickness points shown in fig .
1c , d. 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 m . os had an epi ct of 56.75  1.50 m and an epi average of 55.65  1.22 m . the epithelial topographic thickness variability ( epi variability , fig .
our results show that on average , the epi variability was 1.53  0.21 m for the less affected od , while it was 9.80  0.41 m for the more affected os .
hf - ubm has known intrinsic examiner operative challenges ( both for capture and interpretation ) , and although available for over a decade , it has seen very little clinical use and mainstream practice acceptance
. clinical availability of corneal epithelial mapping by as - oct is currently in practice , and introduces a simple and effective clinical tool for corneal epithelial mapping .
the data are very easily captured and epithelial thickness parameters are automatically calculated by a novel software algorithm and presented in topographic imaging [ 3 , 4 ] . this case illustrates a vivid agreement with previous findings by kanellopoulos et al .   that an overall thicker epithelium with large variations can be observed in the topographically evident kcn eye , and to a much lesser degree in the less affected eye .
qualitatively , the defining feature of the epithelium in kcn is the pattern , such that there is a thin epithelium over the cone surrounded by a thicker epithelium  as can be seen in fig .
1d . quantitatively , epithelial thickness variations can be expressed as the topographic thickness variability and are computed by the standard deviation of the 17 segment thickness points .
specifically , in our case , it was  9.80 m in the affected kcn eye and  1.53 m in the less affected eye . in fig .
2b , the graph compares the corresponding values of epithelial thickness from the hf - ubm study   and the case described herein .
this case not only confirms our findings regarding the increased overall epithelial thickness in ectatic eyes , but also that the new as - oct feature of epithelial imaging may illustrate these differences in a more pronounced way , as indicated by the data shown in fig .
the ease of use of as - oct epithelial imaging in comparison to hf - ubm as well as the increased predictability that may be offered by as - oct epithelial imaging may hold promise for wider clinical application , such as the screening of young adults for early kcn and , in a much wider perspective , potential candidates for laser cornea refractive surgery .
 purposeto evaluate safety , efficacy and ease of measurement of epithelial thickness in a keratoconic patient based on anterior segment optical coherence tomography ( as - oct).methodsa 25-year - old male patient , previously diagnosed with keratoconus , with highly asymmetric manifestation among the two eyes , was subjected to as - oct corneal epithelial imaging . 
 we investigated epithelial thickness and epithelial topographic thickness distribution.resultsmean epithelial thickness was 51.97  0.70 for the less affected right eye ( od ) , and 55.65  1.22 for the more affected left eye ( os ) . 
 topographic epithelial thickness variability for the od was 1.53  0.21 m , while for the os it was 9.80  0.41 m.conclusionsthis case further supports our previous findings with high - frequency ultrasound measurements of the increase in overall epithelial thickness in keratoconic eyes in comparison with normal eyes . as - oct 
 further offers ease of use and possibly higher predictability of measurement . 
 this case report , based on as - oct imaging , verifies increased overall epithelial thickness in keratoconic eyes , as introduced by a previous study [ kanellopoulos et al . 
 : clin ophthalmol 2012;6:789800 ] , based on high - frequency scanning ultrasound biomicroscopy imaging . 
Introduction
Case Report
Discussion
Conclusions
Disclosure Statement