Comparison of specular microscopy and ultrasound pachymetry before and after cataract surgery.
PURPOSE
To compare specular microscopy (Topcon SP-3000P, Topcon Corporation, Tokyo, Japan) and ultrasound (US) technology when evaluating central corneal thickness (CCT) prior to and after phacoemulsification.


METHODS
Corneal edema was assessed in phacoemulsification patients due to senile cataract by measuring CCT preoperatively and 1 day, 1 month, and 3 months postoperatively. Bland-Altman analysis was performed to assess interchangeability between pachymetry techniques for each visit. Repeated measures analysis of variance was performed to evaluate variation in CCT agreement depending on the degree of corneal edema.


RESULTS
One hundred and eighteen patients aged 73.9 ± 10.1 years were recruited. Topcon SP-3000P provided significant (p < 0.0001) lower CCT values than US with and without induced corneal edema. Mean differences between CCT techniques for baseline, 1 day, 1 month and 3 months after cataract surgery were -28.9 ± 22.6, -30.5 ± 41.4, -32.3 ± 16.2 and -33.0 ± 16.9 μm, respectively. The systematic bias observed was not significantly different among the 4 visits (p = 0.59). The estimated limits of agreement (based on 1.96 standard deviation) were substantial, being 90.5, 165.8, 64.9 and 67.5 um at baseline, 1 day and 1 and 3 months.


CONCLUSIONS
Topcon SP-3000P provides similar systematic bias in comparison with US technique for CCT measurements regardless of the degree of corneal edema after phacoemulsification, which should be reduced after applying a constant calibration adjustment of ∼30 μm. However, interchangeability between techniques may be still limited by the notable random measurement error.
['López-Miguel|Alberto|A|', 'Sanchidrián|María|M|', 'Fernández|Itziar|I|', 'Holgueras|Alfredo|A|', 'Maldonado|Miguel J|MJ|']
D000368:Aged D000369:Aged, 80 and over D003315:Cornea D015715:Corneal Edema D063171:Corneal Pachymetry D005260:Female D005500:Follow-Up Studies D006801:Humans D008297:Male D008853:Microscopy D008875:Middle Aged D018918:Phacoemulsification D011183:Postoperative Complications D011184:Postoperative Period D057234:Preoperative Period D015203:Reproducibility of Results D013997:Time Factors
Comparison Specular microscopy Pachymetry Corneal edema