The significance of Vogt's striae in keratoconus as evaluated by in vivo confocal microscopy

To evaluate the association of the presence, extent and width of Vogt's striae with other microstructural corneal alterations in keratoconus using in vivo confocal microscopy (IVCM).

Sixty-eight keratoconic corneas of 68 patients were evaluated with slit-lamp examination (SLE), corneal topography and IVCM. For each eye, the presence, extent and width of alternating light and dark bands (Vogt's striae) observed using IVCM was recorded together with keratocyte and endothelial cell densities, stromal nerve thickness, subbasal nerve density and thickness. The refractive status and the mean and steepest corneal curvatures were noted.

Vogt's striae were present in 43 (63.2%) eyes on SLE and dark bands were present in 53 (77.9%) eyes on IVCM. Compared with patients without dark bands, patients with dark bands had significantly higher refractive errors in spherical equivalents (SE; -8.15 +/- 3.70 vs. -5.18 +/- 2.46 diopters [D], P = 0.007), higher astigmatic errors (-5.88 +/- 2.69 vs. -4.10 +/- 1.84 D, P = 0.027), higher steepest corneal curvatures (54.33 +/- 4.38 vs. 51.23 +/- 3.72 D, P = 0.018), lower anterior stromal keratocyte densities (1106 +/- 172 vs. 1222 +/- 171 cells/mm(2), P = 0.022) and lower nerve fibre densities (18.74 +/- 6.54 vs. 22.66 +/- 6.47 nerves/mm(2), P = 0.054). Compared with patients in whom dark bands were confined to the posterior stroma, patients with dark bands extending into the anterior stroma had significantly higher refractive errors in SE (-11.17 +/- 2.25 vs. -6.34 +/- 3.48 D, P < 0.001), higher astigmatic errors (-7.44 +/- 2.56 vs. -4.69 +/- 2.22 D, P = 0.006) and wider bands (6.0 +/- 2.1 vs. 9.6 +/- 3.1 microm, P < 0.001).

Vogt's striae appear to be more prevalent in keratoconic corneas than can be appreciated clinically. The presence of Vogt's striae may be associated with corneal topographic and microstructural changes.