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Javier Belmonte, Raquel Moral, Silvia Vallcanera, Carlos Belmonte, Jose Belmonte, Juana Gallar, M C. Acosta; Evolution of Mechanical and Chemical Corneal Sensitivity and Innervation after Penetrating Keratoplasty. Invest. Ophthalmol. Vis. Sci. 2011;52(14):360.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the recovery of corneal innervations and sensitivity, 3 to 12 months after unilateral penetrating keratoplasty (PK).
Fifteen patients (9 men, 6 women; 17-79 years) participated voluntarily in the study. Initial diagnosis was keratoconus (n=3), leukoma (n=4), edematous pseudophakic keratopathy (n=5) or previous graft opacification (n=3). Contralateral eyes served as control. At 3, 6, 9 and 12 months after surgery, corneal sensitivity to mechanical (0-200 ml/min flow warm air jets) and chemical stimulation (increasing % of CO2 in air) were analyzed in the center of the cornea of both eyes with the CRCRT-Belmonte esthesiometer. Patients were also explored with confocal microscopy (Confoscan 3) to analyze the presence of corneal nerves. Endothelial cell density and cell area were also evaluated.
Sensitivity threshold to mechanical stimulation was higher in operated eyes but recovered with time, becoming close to control at 12 months (*p<0.01, ANOVA). Chemical threshold appeared slightly higher at 3 months, and recovered afterwards. Subepithelial nerve plexus was absent inside the graft even 12 months after PK, while the presence of stromal nerve trunks increased with time after PK. No significant changes were observed in endothelial cells, which in some donor corneas appeared in better conditions in PK eye than in contralateral.
After PK, stromal and subbasal nerves degenerate inside the graft, and there is a significant decrease in central corneal sensitivity. Sensitivity recovers slowly afterwards, reaching control values in about 12 months, despite the persistent absence of subbasal nerves. Recovered central corneal sensitivity may be mediated by epithelial nerve fibers sprouting from the peripheral host cornea that are not observable by confocal microscopy
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