Eyes implanted with the lens demonstrated greater astigmatic tolerance.
Reviewed byKarolinne Maia Rocha, MD, PhD
The Tecnis Eyhance (DIB00; Johnson & Johnson Vision), a monofocal intraocular lens (IOL) designed to extend the depth of focus, provides greater tolerance to against-the-rule (ATR) astigmatism compared with a standard monofocal IOL (Tecnis ZB00; Johnson & Johnson), according to lead study author Karolinne Maia Rocha, MD, PhD, and colleagues from the Medical University of South Carolina, Storm Eye Institute, Charleston, South Carolina.
In this recently developed category of IOLs designed to lengthen the focal point, this IOL design under discussion modifies the higher-order aspheric anterior optic surface to produce a continuous increase in power from the periphery to the center of the IOL, the investigators explained, that has resulted in improved intermediate vision.
The attempt to improve vision following cataract surgery has been extended to a study of how the IOL is affected by astigmatism. In the current study, the investigators evaluated the tolerance of astigmatic defocus on visual performance in pseudophakic eyes implanted with the DIB00 IOL compared with eyes implanted with a standard monofocal ZCB00 IOL.
The DIB00 IOL is a 1-piece, hydrophobic acrylic, aspheric refractive foldable posterior chamber IOL with the same lens geometry as the Tecnis ZCB00 monofocal IOL.
Rocha and her colleagues conducted a prospective, observational study1 in which they compared the results of the 2 IOLs. Twenty patients each were implanted with either the DIB00 (mean patient age, 66.0 ± 11.0 years) or the ZCB00 IOL (mean patient age, 72.4 ± 4.2 years).
Astigmatic defocus ranging from +0.5 to +2.0 diopters (D) was induced for each astigmatic orientation, ie, ATR, with-the-rule (WTR), and oblique. The outcome measures were the comparisons of the mean visual acuity (VA) at each step of defocus, astigmatic defocus curves, and near and intermediate VAs, the authors recounted.
The secondary outcomes were the mean uncorrected distance VA, the mean corrected distance VA, the mean monocular distance-corrected near VA at 40 cm, and the mean monocular distance-corrected intermediate VA at 66 cm.
The results indicated that the eyes implanted with the DIB00 IOL demonstrated “greater astigmatic tolerance and were more likely to maintain 20/40 or better VA with up to +2.00 D of induced ATR and oblique astigmatism than the ZCB00 IOL.”
The patients with the DIB00 IOL had 1.3 lines of better VA at 2.00 D of ATR astigmatic defocus and 1 line better than the patients with the ZCB00 IOL at 1.50 D of oblique astigmatic defocus.
The distance VAs were comparable between the 2 groups; however, the near and intermediate VAs (both distance-corrected and uncorrected) were better in the eyes with the DIB00 IOL compared with the standard ZCB00 IOL, the authors reported.
The current results agreed with previous reports on how the 2 IOLs tolerated defocus in WTR astigmatism up to +2.00 D .2-5 However, the DIB00 IOL showed significantly better tolerance to induced astigmatism from +0.50 D of defocus to +2.00 D in ATR astigmatism. The DIB00 IOL also performed better than the ZCB00 IOL in oblique astigmatism.
“This study provides insights into the potential role of monofocal IOLs with extended depth of focus features in achieving greater tolerance to residual refractive error,” the investigators commented.
The current results also showed the superiority of the DIB00 IOL in the near and intermediate distance-corrected and uncorrected VAs compared with the standard ZCB00 IOL, which confirms the improved intermediate results reported previously.6-9
The researchers also performed a subanalysis to compare the visual outcomes of the 2 IOLs after controlling for pupillary size.
Rocha and her colleagues noted the results showed a similar statistical trend toward better near and intermediate VAs with the DIB00 IOL compared with the standard monofocal IOL, confirming that the findings achieved in the current study are independent of the pupil size.
“Our study demonstrated that the enhanced monofocal DIB00 IOL had greater tolerance to astigmatism, particularly in the induced ATR orientation compared to the standard monofocal ZCB00 IOL,” the researchers concluded. “Knowledge of the astigmatic tolerance of IOLs is an essential component of surgical planning, because residual astigmatism beyond the IOL’s limit of tolerance may affect visual outcomes.”