Edward Lum1, Blanka Golebiowski2, Helen A Swarbrick2. 1. School of Optometry and Vision Science, University of New South Wales, Sydney, Australia. Electronic address: e.lum@unsw.edu.au. 2. School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
Abstract
PURPOSE: To investigate the recovery of orthokeratology (OK)-induced changes in corneal nerve morphology and sensitivity following lens wear discontinuation, over a 3-month period. METHODS: Sixteen myopic subjects who wore OK lenses during sleep for 3 months discontinued lens wear for 3 months. Corneal nerve morphology and sensitivity were assessed on the right eye only 3 h after waking at the pre-lens wear baseline and after lens wear discontinuation. Corneal nerve fiber density (NFD) and global nerve fiber orientation (GNFO) were assessed by sampling a 1 mm2 area of the subbasal nerve plexus at the corneal apex and temporal mid-periphery using in vivo confocal microscopy. Corneal sensitivity was measured using the Cochet-Bonnet aesthesiometer at similar corneal locations. RESULTS: Significant changes in corneal sensitivity, NFD, and GNFO were observed at various corneal locations during the lens wear discontinuation period. In the central cornea, NFD and corneal sensitivity increased during the 3-month non-lens wear period (p < 0.01); no significant changes in NFD or corneal sensitivity were noted in the mid-peripheral cornea. Central corneal sensitivity recovered to pre-lens wear levels after 1 month of non-lens wear. Central NFD appeared to remain slightly decreased after 3 months of non-lens wear compared to pre-lens wear levels, but this difference did not reach statistical significance (p = 0.09). GNFO did not change significantly at the central cornea during the 3-month non-lens wear period, but altered in a counter-clockwise rotational direction (reversal of OK-induced change) at the mid-peripheral cornea (p < 0.05), although it did not appear to fully recover to pre-lens wear orientation (p = 0.05). CONCLUSIONS: OK lens-induced reduction in corneal sensitivity recovers with cessation of lens wear, returning to pre-lens wear levels shortly after lens wear discontinuation. Changes to nerve morphology induced by OK lens wear, however, appear to recover more slowly towards pre-lens wear levels. This requires confirmation in a longer non-lens wear period.
PURPOSE: To investigate the recovery of orthokeratology (OK)-induced changes in corneal nerve morphology and sensitivity following lens wear discontinuation, over a 3-month period. METHODS: Sixteen myopic subjects who wore OK lenses during sleep for 3 months discontinued lens wear for 3 months. Corneal nerve morphology and sensitivity were assessed on the right eye only 3 h after waking at the pre-lens wear baseline and after lens wear discontinuation. Corneal nerve fiber density (NFD) and global nerve fiber orientation (GNFO) were assessed by sampling a 1 mm2 area of the subbasal nerve plexus at the corneal apex and temporal mid-periphery using in vivo confocal microscopy. Corneal sensitivity was measured using the Cochet-Bonnet aesthesiometer at similar corneal locations. RESULTS: Significant changes in corneal sensitivity, NFD, and GNFO were observed at various corneal locations during the lens wear discontinuation period. In the central cornea, NFD and corneal sensitivity increased during the 3-month non-lens wear period (p < 0.01); no significant changes in NFD or corneal sensitivity were noted in the mid-peripheral cornea. Central corneal sensitivity recovered to pre-lens wear levels after 1 month of non-lens wear. Central NFD appeared to remain slightly decreased after 3 months of non-lens wear compared to pre-lens wear levels, but this difference did not reach statistical significance (p = 0.09). GNFO did not change significantly at the central cornea during the 3-month non-lens wear period, but altered in a counter-clockwise rotational direction (reversal of OK-induced change) at the mid-peripheral cornea (p < 0.05), although it did not appear to fully recover to pre-lens wear orientation (p = 0.05). CONCLUSIONS: OK lens-induced reduction in corneal sensitivity recovers with cessation of lens wear, returning to pre-lens wear levels shortly after lens wear discontinuation. Changes to nerve morphology induced by OK lens wear, however, appear to recover more slowly towards pre-lens wear levels. This requires confirmation in a longer non-lens wear period.