June-July 2020

CATARACT

Study compares small-aperture IOL implantation in one or both eyes


by Liz Hillman Editorial Co-Director


Undilated eye with IC-8

Dilated eye with IC-8
Source (all): Robert Ang, MD

 

When ophthalmologists talk about using small aperture optics to enhance a patient’s depth of focus for increased spectacle independence, most would consider using such technology in the patient’s non-dominant eye. But research involving an IOL that draws on pinhole principles is showing that bilateral implantation might give patients even better visual satisfaction than simply going monolateral.
“The notion of monolateral implantation came from the KAMRA inlay [AcuFocus],” said Robert Ang, MD. “There is an impression that bilateral small aperture will be too dim, visual field constricted, and contrast sensitivity decreased.”
But that’s not what Dr. Ang found in his prospective, non-randomized, non-comparative study that used the IC-8 IOL (AcuFocus), which is not yet approved in the U.S.1 In the study, Dr. Ang implanted a monofocal IOL in one eye of 10 patients and IC-8 in the other. A second group had the IC-8 implanted in both of their eyes, self-selecting to receive IC-8 in the second eye after a positive experience with the first. Visual acuity, patient satisfaction, task performance, visual symptoms, defocus curves, and contrast sensitivity were tracked for at least 12 months and compared between the two groups.
Overall, Dr. Ang found that “the combination of small-aperture IOL and micromonovision allows an improvement of visual performance, especially in the near and intermediate near range,” he wrote in the study. All patients achieved 20/32 or better for uncorrected and corrected distance visual acuity at all distances, regardless of contralateral or bilateral implantation. But uncorrected intermediate and near visual acuity was 0.5–1 line greater in patients who received IC-8 in both eyes. IC-8 implanted bilaterally extended depth of focus range by 0.25 D. Bilateral patients also reported better satisfaction and ease with near tasks and with spectacle independence. Contrast sensitivity was similar in both groups, but bilateral patients reported slightly more glare and halo, while the monolateral group had slightly more blurry or fluctuating vision and double vision (none of these symptoms were statistically significant).
Even with these results, Dr. Ang told EyeWorld that not all patients will be able to tolerate bilateral implantation of a small-aperture IOL. He stressed careful patient selection. “Patient preference has been a good predictor for us in recommending bilateral implantation. We think patients can only decide after they have seen the visual outcome of the first eye,” he said. “Patients who are not satisfied after first eye implantation of IC-8 should not be advised to have the second eye implanted with the same IC-8.”
A previous study published in 2018 compared clinical outcomes of IC-8 implanted in one eye vs. bilaterally.2 This study, in contrast to Dr. Ang’s results, found better intermediate and near vision in the single eye IC-8 group.
“This difference may be attributed to a difference in enrollment criteria. In our study, only patients who voluntarily expressed their desire to have the IC-8 IOL in their second eye after their first eye was treated were enrolled into the study,” Dr. Ang wrote in his study. “Additionally, if the patient reported dissatisfaction with the range of vision in the first treated eye, the target refraction could be adjusted for the second eye to compensate for that dissatisfaction.”
Dr. Ang told EyeWorld that while monolateral implantation of IC-8 is the standard of care in countries where the lens is available, ongoing experience with the lens led to “several justifications … to explore bilateral implantation.”
“Unlike the inlay, which was implanted in the cornea, the IC-8 is implanted behind the pupil and is closer to the nodal point. This allows it to function like the new pupil,” he said. “If the results are very good and patients are satisfied with IC-8 in one eye, there had to be scientific data to answer the question why the lens cannot be implanted in the fellow eye as well. Most patients with corneal irregularities or high aberrations have this problem in both eyes.”
Dr. Ang went on to say that the hesitation in implanting the IC-8 bilaterally stems from the presumption that small aperture optics in both eyes will significantly decrease contrast, constrict the visual field, and affect nighttime vision.
“In accepting only patients who request second eye implantation, we have selected patients who are not symptomatic of these problems and improve the chance of achieving high patient satisfaction after bilateral implantation,” he said.

About the doctor

Robert Ang, MD
Asian Eye Institute
Makati City, Philippines

References

1. Ang RE. Visual performance of a small-aperture intraocular lens: first comparison of results after contralateral and bilateral implantation. J Refract Surg. 2020;36:12–19.
2. Dick HB, et al. Binocular and monocular implantation of small-aperture intraocular lenses in cataract surgery. J Refract Surg. 2018;34:629–631.

Relevant disclosures

Ang
: AcuFocus

Contact

Ang: angbobby@hotmail.com


IC-8 for corneal irregularities

While perhaps originally created as a presbyopia-correcting IOL, others are finding utility in IC-8 addressing corneal irregularities. A prospective study published earlier this year described IC-8 in 17 patients with non-progressive keratoconus, previous penetrating keratoplasty, post-RK, or ocular trauma scarring. Corrected distance visual acuity and uncorrected visual acuity at distance, intermediate, and near improved in all patients postop. Scores on a quality of life assessment also improved.

Reference

Shajari M, et al. Safety and efficacy of a small-aperture capsular bag-fixated intraocular lens in eyes with severe corneal irregularities. J Cataract Refract Surg. 2020;46:188–192.

Study compares small-aperture IOL implantation in one or both eyes Study compares small-aperture IOL implantation in one or both eyes
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