title: Three-dimensional mapping of the orientation of collagen corneal lamellae in healthy and keratoconic human corneas using SHG microscopy.
abstract: Keratoconus is an eye disorder that causes the cornea to take an abnormal conical shape, thus impairing its refractive functions and causing blindness. The late diagnosis of keratoconus is among the principal reasons for corneal surgical transplantation. This pathology is characterized by a reduced corneal stiffness in the region immediately below Bowman's membrane, probably due to a different lamellar organization, as suggested by previous studies. Here, the lamellar organization in this corneal region is characterized in three dimensions by means of second-harmonic generation (SHG) microscopy. In particular, a method based on a three-dimensional correlation analysis allows to probe the orientation of sutural lamellae close to the Bowman's membrane, finding statistical differences between healthy and keratoconic samples. This method is demonstrated also in combination with an epi-detection scheme, paving the way for a potential clinical ophthalmic application of SHG microscopy for the early diagnosis of keratoconus. SHG image acquired with sagittal optical sectioning (A) of a healthy cornea and (B) of a keratoconic cornea. Scale bars: 30 μm.
authors.affiliation: National Institute of Optics, National Research Council (INO-CNR), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Mercatelli
authors.affiliation: Institute of Applied Physics "N. Carrara" (IFAC-CNR), Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Ratto
authors.affiliation: Institute of Applied Physics "N. Carrara" (IFAC-CNR), Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Rossi
authors.affiliation: Institute of Applied Physics "N. Carrara" (IFAC-CNR), Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tatini
authors.affiliation: U.O. Oculistica Nuovo Ospedale S. Stefano, Via Suor Niccolina Infermiera 20, 59100, Prato, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Menabuoni
authors.affiliation: U.O. Oculistica Nuovo Ospedale S. Stefano, Via Suor Niccolina Infermiera 20, 59100, Prato, Italy.
authors.forename: Alex
authors.initials: A
authors.lastname: Malandrini
authors.affiliation: C.S.O S.r.l, Via degli Stagnacci 12/e, 50018, Scandicci, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Nicoletti
authors.affiliation: Institute of Applied Physics "N. Carrara" (IFAC-CNR), Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Pini
authors.affiliation: National Institute of Optics, National Research Council (INO-CNR), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy.|European Laboratory for Non-Linear Spectroscopy (LENS), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy.|Department of Physics, University of Florence, Via G. Sansone 1, 50019, Sesto Fiorentino, Italy.
authors.forename: Francesco Saverio
authors.initials: FS
authors.lastname: Pavone
authors.affiliation: National Institute of Optics, National Research Council (INO-CNR), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy.|European Laboratory for Non-Linear Spectroscopy (LENS), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Cicchi
mesh_terms: D003094:Collagen / Q000648:ultrastructure*; D003315:Cornea / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D007640:Keratoconus / Q000000981:diagnostic imaging*; D008853:Microscopy / Q000379:methods*
chemical_list: D003094:Collagen
keywords: Second-Harmonic Generation (SHG) microscopy; collagen; cornea; keratoconus