title: Total spherical aberration of the cornea in patients with cataract.
abstract: OBJECTIVE
  To investigate the distribution of corneal spherical aberration in patients with cataract using the Pentacam HR.
  
  
  METHODS
  Consecutive cataract patients were examined using the Pentacam HR high-resolution rotating Scheimpflug camera (Oculus, Wetzlar, Germany). In one eye of each patient, the root-mean-square (RMS) of anterior, posterior, and total corneal spherical aberration Z4(0) was calculated by ray-tracing on an area of 6 mm diameter. The Pearson correlation coefficient (r) was used to assess correlations between Z4(0) RMS values and age/total corneal refractive power. The χ2 test was used to compare the proportion of eyes qualifying for spherically neutral or negatively aspheric (-0.17 and -0.27 μm) intraocular lenses (IOLs) by targeted level of residual spherical aberration.
  
  
  RESULTS
  Fifty-seven men and 92 women were included (mean [±SD] age, 71.73 [±9.12] years). The RMS mean (±SD) values of Z4(0) were +0.353 (±0.132) μm, -0.121 (±0.034) μm, and +0.328 (±0.132) μm, respectively, for the anterior, posterior, and total cornea. The anterior, posterior, and total Z4(0) were on average significantly higher (p < 0.001) in women than in men. In both sexes, statistically significant (p < 0.05) age-related changes were found for the anterior and total Z4(0) but not for the posterior Z4(0) (p > 0.05). The total Z4(0) and total corneal refractive power were significantly correlated in men (p = 0.01) but not in women (p = 0.14). For postoperative targets of 0 ± 0.05/+0.10 ± 0.05 μm residual Z4(0), the proportion of eyes that would have qualified for implantation of negatively aspheric IOLs with -0.17 and with -0.27 μm was similar (61.1 and 56.3%, respectively; p = 0.09); significantly fewer eyes (6.7%) would have qualified for implantation of neutrally aspheric IOLs (p > 0.05).
  
  
  CONCLUSIONS
  Total corneal Z4(0) measured by Pentacam HR might be higher than that reported in previous studies. In most patients, the implantation of commercially available negatively aspheric IOLs would partially compensate for the positive total corneal Z4(0).
authors.affiliation: *MD, PhD †MD Department of Surgical Sciences, Ophthalmology Institute, University of Turin, Turin, Italy (all authors).
authors.forename: Ugo
authors.initials: U
authors.lastname: de Sanctis
authors.forename: Luisa
authors.initials: L
authors.lastname: Vinai
authors.forename: Elena
authors.initials: E
authors.lastname: Bartoli
authors.forename: Piero
authors.initials: P
authors.lastname: Donna
authors.forename: Federico
authors.initials: F
authors.lastname: Grignolo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000503:physiopathology*; D003315:Cornea / Q000503:physiopathology*; D057108:Corneal Wavefront Aberration / Q000503:physiopathology*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000295:instrumentation