Evaluating soft contact lens quality: a manufacturer's perspective

This study was designed to compare quality control between six aphakic contact lens brands. The methodology eliminates the sampling and experimental variables of previous studies. The lenses were all purchased new at +13.00 D power, with the same number of lenses and distribution of manufacturing batch/lots per brand. We measured or assessed 120 study lenses (20 per brand) for diameter, front sagittal height, power and image quality, center thickness, surface and edge quality, and edge design. The base curve radius was calculated accurately using lens cross-sectioning techniques. The reproducibility of measured lens parameters (precision) and conformance to label claims (accuracy) were tabulated separately and the lens brands were ranked and grouped statistically. The tabulated results are represented graphically in one spread sheet where selected American National Standards Institute (ANSI) tolerances were used as a standard to which all lens brands were compared. Lens brands coded as Brand A and Brand B rated the highest using our criterion for ranking overall quality control.