Refractive lens exchange

Posterior corneal astigmatism in refractive lens exchange surgery

PURPOSE

To assess the anterior, posterior and total corneal spherical and astigmatic powers in patients undergoing refractive lens exchange (RLE) surgery.

METHODS

In 402 consecutive patients planned for RLE at Koskelas Eye Clinic, Luleå, Sweden, right eye data from pre- and postoperative subjective refraction, preoperative IOLMaster(®) biometry and Pentacam HR(®) measurements were collected. Postoperative Pentacam HR(®) data were collected for 54 of the patients. The spherical and astigmatic powers of the anterior and posterior corneal surfaces and for the total cornea were assessed and compared, and surgically, induced astigmatism was calculated using vector analysis.

RESULTS

The spherical power of the anterior corneal surface was 48.18 ± 1.69D with an astigmatic power of 0.83 ± 0.54D. The corresponding values for the posterior surface were -6.05 ± 2,52D and 0.26 ± 0.15D, respectively. The total corneal spherical power calculated with ray tracing was 42.47 ± 2.89D with a 0.72 ± 0.48D astigmatic power, and the corresponding figures obtained by estimating the posterior corneal surface were 43.25 ± 1.51D (p < 0.001) with a 0.75 ± 0.49D astigmatic power (p = 0.003). In eyes with anterior astigmatism with-the-rule, the total corneal astigmatism is overestimated if the posterior corneal surface is estimated; in eyes, with against-the-rule astigmatism it is underestimated. Had the posterior corneal surface been measured in this material, 14.7% of the patients would have received a spheric instead of a toric IOL, or vice versa.

CONCLUSION

Estimating the posterior corneal surface in RLE patients leads to systematic measurement errors that can be reduced by measuring the posterior surface. Such an approach can potentially increase the refractive outcome accuracy in RLE surgery.

A prospective randomized clinical evaluation of 3 presbyopia-correcting intraocular lenses after cataract extraction

PURPOSE

To compare contrast sensitivity, visual acuity (VA), and halos in subjects bilaterally implanted with 1 of 3 FDA-approved presbyopia-correcting intraocular lenses.

DESIGN

Prospective, randomized, partially masked, multicenter clinical trial.

METHODS

Seventy-eight subjects were randomized sequentially for bilateral implantation with the Crystalens AO (Bausch & Lomb Surgical), AcrySof IQ ReSTOR +3.0 (Alcon Laboratories), or Tecnis Multifocal (Abbott Medical Optics) lenses. Subjects were evaluated through visit 4 (4 to 6 months after surgery) with the following monocular and binocular assessments: high- and low-contrast VA, contrast sensitivity without glare, halos or starbursts, defocus curves, optical scatter, retinal point spread function, and safety.

RESULTS

The Crystalens AO and ReSTOR +3.0 demonstrated better monocular and binocular contrast sensitivity without glare at low to mid spatial frequencies compared with the Tecnis Multifocal lens. Binocular uncorrected distance VA was not significantly different between the 3 lenses. The Crystalens AO had significantly better binocular low-contrast distance-corrected VA than the ReSTOR +3.0 and better mean monocular low-contrast DCVA than the Tecnis Multifocal lens. The Crystalens AO demonstrated significantly better monocular and binocular uncorrected and distance-corrected intermediate VA than the ReSTOR +3.0 or Tecnis Multifocal lenses. The ReSTOR+3.0 lens had significantly better monocular and binocular uncorrected and distance-corrected near VA tested at 40 cm compared with the Crystalens AO and Tecnis Multifocal lens. The Crystalens AO elicited significantly less halos than the Tecnis Multifocal lens and less optical scatter than the ReSTOR +3.0 or Tecnis Multifocal lens.

CONCLUSIONS

The Crystalens AO had statistically better uncorrected intermediate VA and distance-corrected intermediate VA than the ReSTOR +3.0 or Tecnis Multifocal lenses and fewer photic phenomenon than the Tecnis Multifocal lens. Both multifocals had better distance-corrected near VA and uncorrected near VA than the Crystalens AO. These findings may guide intraocular lens selection for individual patients seeking to optimize vision at specific vergences or lighting conditions.

Visual performance of patients with bilateral vs combination Crystalens, ReZoom, and ReSTOR intraocular lens implants

PURPOSE

To compare the visual performance of patients with bilateral vs combination Crystalens, ReZoom, and ReSTOR intraocular lens (IOLs) implants.

DESIGN

Prospective, nonrandomized study.

METHODS

Forty-nine patients were implanted with bilateral Crystalens (Eyeonics, Aliso Viejo, California, USA), ReSTOR (Alcon Laboratories, Fort Worth, Texas, USA), and ReZoom (American Medical Optics, Santa Clara, California, USA) or combined Crystalens and ReSTOR or Crystalens and ReZoom IOLs after phacoemulsification. Monocular and binocular testing four to six months after surgery included uncorrected and best-spectacle corrected visual acuity at distance, intermediate, and near vision; mesopic contrast sensitivity function with and without glare; and quality-of-life and vision surveys six months after surgery.

RESULTS

Monocular testing showed that eyes with Crystalens accommodating IOL had statistically better best-spectacle corrected distance, uncorrected and distance-corrected intermediate, and best-corrected near vision. Eyes with the ReSTOR multifocal IOL had better uncorrected near vision, required the lowest reading add, and had the lowest uncorrected and distance-corrected intermediate vision. Monocular mesopic contrast sensitivity with and without glare was better with the Crystalens IOL vs either multifocal IOL at specific spatial frequencies. The binocular subjective quality of vision and quality of life questionnaires were favorable for the bilateral Crystalens group.

CONCLUSIONS

Any combination of Crystalens in one or both eyes was better for intermediate vision. Any combination of ReSTOR in one or both eyes was better for near vision. The Crystalens and ReSTOR combination had better mean intermediate and near vision overall. A multifocal IOL in one or both eyes was associated with lower contrast sensitivity and more subjective reports of photic phenomena. The accommodating and multifocal IOL combinations elicited less night glare symptoms than in patients with either bilateral multifocal IOL, but more than with bilateral Crystalens implantation.