Shifting of the Line of Sight in Keratoconus Measured by a Hartmann-Shack Sensor

Purpose To evaluate ocular wavefront aberrations owing to keratoconus compared with normal controls and to describe the changes in the axis of line of sight (LoS) among keratoconic patients. Design Prospective case-control study. Participants Fifty-five eyes of 30 patients with keratoconus and 100 eyes of 50 refractive surgery candidates with normal corneas. Methods Ocular aberrations over a 4.5 mm (undilatated) pupil were measured with a Hartmann-Shack sensor. Corneal topographic measurement was performed with a Tomey corneal topographer. The axis of the displacement of LoS was calculated by vector analysis. Main Outcome Measures Root mean square (RMS) and higher order RMS values, ocular aberrations up to the 6th Zernike order and the distance of the LoS from the pupillary center ( x and y offset values) in keratoconic and normal eyes were measured with aberrometry. The steepest and average keratometric values and the axis of the steepest meridian were measured in keratoconic eyes with topography. Correlations were made between the size and the direction of the shift in the LoS and ocular aberrations. Results The following parameters were significantly higher in the keratoconus group compared to the control group: higher order RMS ( P