title: Application of high resolution OCT to evaluate irregularity of Bowman's layer in asymmetric keratoconus.
abstract: Irregularity of the Bowman's layer (BL) in keratoconus (KC, sample size (n) = 28) and forme fruste keratoconus (FFKC, n = 18) eyes was evaluated. Subjects underwent high resolution OCT imaging (Bioptigen Inc., USA) and corneal tomography (Pentacam v1.20r41, OCULUS Optikgeräte GmbH, Germany). Anterior edge of the BL was segmented. A Bowman's roughness index (BRI) was defined as the sum of the enclosed areas between segmented edge and a smooth 3rdorder polynomial fit to the edge. BRI was compared with corneal aberrations, Keratoconus percentage index (KISA), Cone location magnitude index (CLMI) and Belin-Ambrosio enhanced ectasia display overall deviation index (BAD-D). Area under the curve (AUC) was determined with logistic regression (LR). Mean BRI (×10-3) was 2.12 mm2, 1.81 mm2and 1.7 mm2in normal (n = 26), FFKC and KC eyes, respectively (p < 0.001). BAD-D (0.79) and BRI (0.74) had the best AUC for FFKC. By combining BAD-D and BRI, the AUC improved to 0.85 (p = 0.01). For KC eyes, KISA (0.94), CLMI (0.88), BAD-D (0.96) and aberrations had comparable AUC (p > 0.05). However, LR with BRI and other indices didn't improve the AUC in KC eyes (p > 0.05). BRI was significantly reduced in FFKC and KC eyes. It improved the detection of FFKC but not KC eyes.
authors.affiliation: Cornea and Refractive Surgery Division, Narayana Nethralaya, #258A Hosur Road, Bommansandra, Bangalore, 560099, India.
authors.forename: Natasha
authors.initials: N
authors.lastname: Pahuja
authors.affiliation: Cornea and Refractive Surgery Division, Narayana Nethralaya, #258A Hosur Road, Bommansandra, Bangalore, 560099, India.
authors.forename: Rushad
authors.initials: R
authors.lastname: Shroff
authors.affiliation: Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
authors.forename: Pratik
authors.initials: P
authors.lastname: Pahanpate
authors.affiliation: Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
authors.forename: Mathew
authors.initials: M
authors.lastname: Francis
authors.affiliation: Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
authors.forename: Leio
authors.initials: L
authors.lastname: Veeboy
authors.affiliation: Cornea and Refractive Surgery Division, Narayana Nethralaya, #258A Hosur Road, Bommansandra, Bangalore, 560099, India.
authors.forename: Rohit
authors.initials: R
authors.lastname: Shetty
authors.affiliation: Department of Ophthalmology, Maastricht University Medical Center, The Netherlands.
authors.forename: Rudy M M A
authors.initials: RMMA
authors.lastname: Nuijts
authors.affiliation: Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Sinha Roy
mesh_terms: D000328:Adult; D003315:Cornea / Q000000981:diagnostic imaging*; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D006801:Humans; D007640:Keratoconus / Q000000981:diagnostic imaging*; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D055815:Young Adult
keywords: Bowman's layer; Pentacam; cornea; keratoconus; optical coherence tomography