Testing the dioptric power accuracy of exact-power-labeled intraocular lenses.
OBJECTIVE
To test the accuracy of exact-power-labeled intraocular lenses (IOLs) in a limited independent study.


METHODS
U.S. Food and Drug Administration Optical Testing Lab.


METHODS
Hydrophilic acrylic IOLs were measured using a new confocal laser method for dioptric power measurement per International Organization for Standards standard 11979-2 and American National Standards Institute standard Z80.7. Some of the IOLs were measured at 22 degrees C and 35 degrees C.


RESULTS
For the 18 IOLs tested, the mean difference between the manufacturer's exact labeled power (D(EL)) and the power measured in the study (D(M)) was 0.18 diopter (D) +/- 0.12 (SD) and between D(M) and the usual normal rounded-off (0.50 D steps) dioptric power (D(UL)) labeling, 0.23 +/- 0.09 D (difference 0.05 D). For 15.00 to 20.0 D IOLs, the mean difference between D(M) and D(EL) was 0.08 +/- 0.05 D and between D(M) and D(UL), 0.17 +/- 0.06 D (difference 0.09 D). For IOLs of 20.00 D or greater, the mean difference between D(M) and D(EL) was 0.24 +/- 0.11 D and between D(M) and D(UL), 0.27 D +/- 0.08 D (difference 0.03 D). When the IOL hydration temperature increased from 22 degrees C to 35 degrees C (4 IOLs tested), the IOL power increase on average was approximately 0.13 D.


CONCLUSIONS
The small improvement in power-prediction accuracy for exact-power-labeled IOLs decreased in IOLs of 20.00 D or greater. For IOLs of 15.00 to 20.00 D, the increased accuracy (+/-0.09 D) was statistically significant and could increase predictability of postoperative refractions. Acrylic dioptric power was directly proportional to temperature.
Hoffer
Kenneth J
KJ
University of California, Los Angeles, California, USA. khoffermd@aol.com
Calogero
Don
D
Faaland
Robert W
RW
Ilev
Ilko K
IK
D003941:Diagnostic Techniques, Ophthalmological; D007910:Lenses, Intraocular; D008689:Methacrylates; D055095:Optics and Photonics; D011108:Polymers; D019904:Polymethyl Methacrylate; D012015:Reference Standards; D015203:Reproducibility of Results; D014481:United States; D014486:United States Food and Drug Administration
D008689:Methacrylates; D011108:Polymers; C104020:poly(methylmethacrylate-co-ethylhexylmethacrylate); D019904:Polymethyl Methacrylate