Depth-of-focus enhancement makes target easier to hit

Digital Edition, Ophthalmology Times: October 1, 2021, Volume 46, Issue 16

Lens an option for complicated eyes, astigmatism, monovision candidates.


Special to Ophthalmology Times®

I recently began implanting the Tecnis Eyhance IOL (ICB00, Johnson + Johnson Vision), a new monofocal/monofocal toric IOL with an optimized power profile.

It has quickly become our default lens choice for any patient having premium cataract surgery who is a not a candidate for a presbyopia-correcting IOL.

In our practice, this includes anyone undergoing femtosecond laser surgery with correction for astigmatism (toric IOL and/or arcuate incisions).

Optical bench testing showed that the ICB00 is comparable to the Tecnis Monofocal 1-Piece IOL, model ZCB00 in terms of distance image quality, while providing better simulated intermediate vision.1

Hitting the distance target
The biggest advantage of using the lens, for me, is being able to meet patients’ expectations for distance vision.

We know high-quality distance vision demands that the refractive result be within 0.5 D of emmetropia, with minimal residual astigmatism. Yet ophthalmologists achieve this target only about 70% of the time.2

The ICB00 lens is designed to slightly extend the depth of focus. This increase is not as great as other presbyopia-correcting and extended depth-of-focus lenses, but it is enough to give a broader landing zone.

If the patient has a +0.25 D to +0.50 D outcome, they will see well at distance. If the outcome is –0.25 D to –0.50 D, they will see well at distance and possibly have a little better intermediate visual acuity.

Thus far, our distance results are excellent. In the first 42 eyes I implanted the lens in, 10 had conditions such as diabetic retinopathy or an epiretinal membrane (ERM) that limited visual potential.

Of the 32 eyes with no other ocular pathology (mean patient age, 74), the mean distance acuity was 20/25.

The slight depth of focus may also help to mask small amounts of residual astigmatism; studies with other IOLs have shown that greater depth of focus improves tolerance to astigmatism.3-5

Although useful in many cases, a patient’s improved tolerance to astigmatic error could be particularly beneficial for surgeons who do not have intraoperative aberrometry, digital marking, or a femtosecond laser to help them position toric lenses precisely on the steep axis.

I have found the broader landing zone particularly helpful in those eyes for which IOL power calculation is challenging.

For example, one patient with a very large ERM had 20/30 uncorrected distance acuity on day 1 after surgery and claims not to even notice the central distortion much anymore.

It is hard to predict refractive outcomes in such eyes because the ERM tugs on the retina and can make the patient more myopic than intended.

Additionally, if the patient later requires a membrane peel, that may cause the retina to sit about 100 µm more posteriorly, changing the refraction by up to 0.25 D.

With the slight extension in depth of focus in the ICB00 lens, I can give patients with ERM good vision now and enable them to retain it later even if they eventually require a membrane peel.


An IOL with a boost

Preclinical studies showed an improvement over the Tecnis monofocal through –1.00 to –2.00 D of defocus, a gain of about 0.1 logMAR.1

Historically, we have not measured intermediate or near vision in patients with monofocal IOLs, but in patients with the ICB00 lens we are checking near vision at a functional distance of about 20 inches.

At this distance, 97% of patients have a Jaeger (J) score of 10 or better.

A few patients have presented for postoperative appointments with surprisingly good near vision.

One such patient, with +4.0 D hyperopia, had enjoyed good vision after LASIK but since the onset of presbyopia had been struggling to see well at any distance without correction.

He wore contact lenses but, as an avid windsurfer, was unhappy that if he lost a lens or if the wind was irritating his eyes, he could not see well.

We implanted the ICB00 lens in both eyes. At 1 month, he could see 20/20 and J5 in one eye and 20/20 and J1 in the other. This is an unusually good near result, and certainly not one that I would promise patients preoperatively.

It is possible that the high lens power implanted in this case (28 D) or some corneal aberrations from the earlier LASIK procedure contributed to the result.

As we gain more experience with this lens, we may understand better which eyes are likely to get better than average results.

Being designed to provide a small extension in depth of focus may also make the ICB00 a good lens to use when a monovision target is planned. Mini-monovision works quite well for taller people with long arms.

In my practice, this lens fills a gap. I expect it to replace standard monofocal and monofocal toric IOLs in about 40% of my cases.

About the author

Carlton Yuen, MD
E: dr.yuen@hotmail.com

Yuen is in practice at Aloha Vision Consultants in Honolulu, Hawaii. He served as chairman of the Department of Ophthalmology at Kuakini Medical Center in Honolulu and chief of the Ophthalmology Division at Hawaii Medical Center West in Ewa Beach. He is a consultant for Johnson + Johnson Vision.

Caitlin Yuen is an ophthalmic assistant at Aloha Vision Consultants who compiled the data on Tecnis Eyhance patients.

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References

1. Alarcon A, Cánovas C, Koopman B, Weeber H, Auffarth GU, Piers PA. Enhancing the intermediate vision of monofocal intraocular lenses using a higher order aspheric optic. J Refract Surg. 2020;36(8):520-527. doi:10.3928/1081597X-20200612-01

2. Ma J, El-Defrawy S, Lloyd J, Rai A. Prediction accuracy of intraoperative aberrometry compared with preoperative biometry formulae for intraocular lens power selection. Can J Ophthalmol. Published online July 22, 2021. doi:10.1016/j.jcjo.2021.06.024

3. Carones F. Residual astigmatism threshold and patient satisfaction with bifocal, trifocal and extended range of vision intraocular lenses (IOLs). Open J Ophthalmol. 2017;7(1):1-7. doi:10.4236/ojoph.2017.71001

4. Ang RE. Comparison of tolerance to induced astigmatism in pseudophakic eyes implanted with small aperture, trifocal, or monofocal intraocular lenses. Clin Ophthalmol. 2019;13:905-911. doi:10.2147/OPTH.S208651

5. Ben Yaish S, Zlotnik A, Raveh I, Yehezkel O, Belkin M, Zalevsky Z. Intraocular omni-focal lens with increased tolerance to decentration and astigmatism. J Refract Surg. 2010;26(1):71-76. doi:10.3928/1081597X-20101215-12