Abstract
Purpose: :
To investigate the anatomy of corneal nerve trunks distribution using confocal microscopy.
Methods: :
Subjects: The study consisted of ten eyes from four males and one female. Subjects had no history of ocular surgery or diseases. Each patient was placed before the confocal microscope. Two passes were performed in each of the four quadrants (3, 6, 9, 12 o’clock positions) one half millimeter from the limbus, the first in an anterior to posterior direction, and the second in a posterior to anterior direction. Corneal nerve trunks were counted in each quadrant. Small subepithelial nerves were not included.
Results: :
Using the confocal microscope, it was determined that the mean number of corneal nerve trunks in the superior quadrant was 2.1 with a standard deviation (SD) of 0.7, while in the nasal quadrant, it was 2.2 with SD of 1.5. The difference in the number of corneal nerve trunks between the superior and nasal quadrants was statistically not significant, with a resulting GEE (generalized estimating equation) p–value of 0.77. The GEE methodology has been used to account for the fact that there are 2 eyes per patient.
Conclusions: :
According to our data, there was no statistically significant difference between the number of corneal nerve trunks in the superior and nasal quadrants. This would imply that there is no difference in induced corneal hypoesthesia caused by LASIK flaps with hinges in these quadrants. Our study indicates that both nasal hinged and superior hinged flaps transect approximately the same number of nerves and therefore the decision to create either flap in LASIK surgery should be made on other factors, for example flap stability, and surgeon's preference.
Keywords: cornea: clinical science • innervation: sensation • refractive surgery: LASIK