Abstract
Purpose: :
To define the cut-off values of wavefront aberrations by comparing in normal eyes with keratoconic suspect, LASIK, or cataractous eyes.
Methods: :
Wavefront sensing was performed in 65 normal eyes (N), 46 keratoconic suspect eyes (KCS), 50 LASIK eyes (L) and 111 cataractous eyes (CAT) with a Shack-Hartmann aberrometer (KR-9000PW, Topcon). The ocular wavefront aberrations were analyzed with normalized Zernike polynomials up to 4th order for 4-mm diameter circular area and with normalized Zernike polynomials up to 6th order for 6-mm. Means and standard deviations (SD) were calculated with RMS of total high-order aberrations (TH-RMS). In each category, the receiver operating characteristic (ROC) between normal and the category was analyzed. Cut-off values of the RMS were determined with both sensitivity and the specificity.
Results: :
TH-RMSs for each category were 0.09±0.03(mean±SD) µm (N), 0.36±0.26 µm (KCS), 0.19±0.07µm (L), and 0.27±0.14µm (CAT) for 4-mm diameter, and 0.30±0.11 µm (N), 1.05±0.65 µm (KCS), 0.74±0.24 µm (L), and 0.74±0.33 µm (CAT) for 6-mm diameter. The mean of TH-RMS for the normal eye was in agreement with previous studies(Howland, 2002). The ROC analysis showed the cut-off values of N to KCS, to L, and to CAT with 4mm TH-RMS (area under ROC curve) were 0.13 µm (0.928), 0.13 µm (0.909), and 0.15 µm (0.957) respectively. The cut-off of 6mm TH-RMS were 0.43 µm (0.908), 0.49 µm (0.987), and 0.45 µm (0.954).
Conclusions: :
We determined the cut-off value from the average of three ROC results. The cut-off value of TH-RMS was 0.14 µm in 4-mm pupil and 0.46 µm in 6-mm pupil. If we suppose the distribution of TH-RMS of normal eyes is Gaussian , 95%( mean±1.96SD) of the normal eyes lie between 0.03 to 0.15 for 4-mm diameter and 0.08 to 0.52 for 6-mm diameter. This is consistent with the cut-off values we obtained in this study.
Keywords: aberrations • cataract • keratoconus