Implantation of a non-diffractive extended depth-of-focus IOL and a monofocal IOL after myopic corneal laser refractive surgery: a randomized controlled trial.

In 1998 the FDA gave the first approval for LASIK (laser in situ keratomileusis) surgery, a safe procedure to adjust the refractive status of the cornea in pre-presbyopic and pre-cataract patients.(1) The population of post-LASIK patients requiring cataract surgery and seeking spectacle independence is expected to increase in the coming years. However, using presbyopia correcting multifocal intraocular lenses (mIOLs) after preceding corneal refractive surgery is controversial due to the potential side-effects of these mIOLs such as halos and glare, and less predictable postoperative refractive outcomes. This unpredictability arises from changes of the ratio between the anterior and posterior corneal curvatures, leading to inaccuracies in total corneal refractive power estimation and ineffective lens position predictions with the standard IOL calculation formulas.(2-4)

Currently, the standard care for cataract surgery after corneal laser treatment involves the implantation of the Clareon monofocal lens, which is widely regarded as the standard option. Patients preferring greater spectacle independence can opt for an Extended Depth of Focus (EDOF) IOL, such as the Alcon Clareon Vivity®, if no medical contraindications exist. However, these patients must perform co-payment for this EDOF IOL. 

The Alcon Clareon Vivity® is an EDOF IOL that consists of a central 2.2 mm wavefront-shaping area with smooth continuous anterior surface transitions from the periphery to the center for providing the extended focal range. The wavefront-shaping area stretches and shifts the wavefront, which results in an extended focal range of > 1.5 diopters (D). This design provides continuous vision from distance to intermediate distances and preserves the contrast sensitivity. Besides, this IOL has a monofocal visual disturbance profile without the halos and glare that are frequently experienced by patients after mIOL implantation.(5) For this reason, the non-diffractive IOL design could become a preferred choice for post-LASIK patients.

Despite promising outcomes for EDOF lenses in retrospective and prospective cohort studies, no robust evidence currently supports their superiority over monofocal lenses in post-corneal laser patients.(6-8) Moreover, post-LASIK patients face an increased risk of residual refractive error (target deviation) after IOL implantation, with the risk and its impact on visual acuity varying by lens design. Scientific data on the risks and visual impact of such deviations remain limited, further emphasizing the need for a comparative study.

This study aims to address this knowledge gap by conducting a double-masked, randomized, prospective clinical trial comparing the visual function of bilateral non-diffractive advanced monofocal Alcon Clareon Vivity® IOL implantation with the standard Alcon Clareon monofocal IOL, both targeted for mini-monovision, in patients with previous myopic laser corneal surgery. By providing insight into visual performance, this trial seeks to clarify whether the EDOF IOL offers significant advantages over the monofocal IOL in this specific patient group.


References:
1. Solomon KD, Fernández de Castro LE, Sandoval HP, Biber JM, Groat B, Neff KD, 
et al. LASIK world literature review: quality of life and patient satisfaction. 
Ophthalmology. 2009;116(4):691-701.
2. Seitz B, Langenbucher A, Nguyen NX, Kus MM, Küchle M. Underestimation of 
intraocular lens power for cataract surgery after myopic photorefractive 
keratectomy11The authors have no proprietary interest in the development or 
marketing of this or any competing instrument or piece of equipment. 
Ophthalmology. 1999;106(4):693-702.
3. Chan TC, Liu D, Yu M, Jhanji V. Longitudinal evaluation of posterior corneal 
elevation after laser refractive surgery using swept-source optical coherence 
tomography. Ophthalmology. 2015;122(4):687-92.
4. Wang L, Hill WE, Koch DD. Evaluation of intraocular lens power prediction 
methods using the American Society of Cataract and Refractive Surgeons 
Post-Keratorefractive Intraocular Lens Power Calculator. J Cataract Refract 
Surg. 2010;36(9):1466-73.
5. van Amelsfort T, Webers VSC, Bauer NJC, Clement LHH, van den Biggelaar F, 
Nuijts R. Visual outcomes of a new nondiffractive extended depth-of-focus 
intraocular lens targeted for minimonovision: 3-month results of a prospective 
cohort study. J Cataract Refract Surg. 2022;48(2):151-6.
6. Bucci FA, Jr. Patient Satisfaction, Visual Outcomes, and Regression Analysis 
in Post-LASIK Patients Implanted With Multifocal, EDOF, or Monofocal IOLs. Eye 
Contact Lens. 2023;49(4):160-7.
7. Christopher KL, Miller DC, Patnaik JL, Lynch AM, Davidson RS, Taravella MJ. 
Comparison of Visual Outcomes of Extended Depth of Focus Lenses in Patients 
With and Without Previous Laser Refractive Surgery. J Refract Surg. 
2020;36(1):28-33.
8. Ferreira TB, Pinheiro J, Zabala L, Ribeiro FJ. Comparative analysis of 
clinical outcomes of a monofocal and an extended-range-of-vision intraocular 
lens in eyes with previous myopic laser in situ keratomileusis. J Cataract 
Refract Surg. 2018;44(2):149-55.

The primary objective of this study is to compare the mean binocular DCIVA at 
66 cm under photopic conditions 3 months after cataract surgery, in a series of 
patients, who previously underwent myopic laser surgery, bilaterally implanted 
with the non-diffractive advanced monofocal Clareon Vivity® IOL 
(intervention-group) versus the Alcon monofocal Clareon IOL 
(control-group) both targeted for mini-monovision.

The design of this study is a multicenter, double masked, prospective 
randomized controlled trial. Patients who previously underwent myopic corneal 
refractive surgery on both eyes and now suffering from cataract which requires 
cataract surgery on both eyes will be included in the study. This study will be 
conducted in 3 different centers in 2 different countries. 
The study consists of two study-groups: intervention group (bilateral 
implantation with the non-diffractive advanced monofocal Clareon Vivity® 
IOL) and the control-group (bilateral implantation with the Alcon monofocal 
Clareon IOL both targeted for mini-monovision. A total of 48 
patients will be randomized into either the intervention-group or the 
control-group at a 1:1 ratio. Patients and study-optometrists/research 
assistants doing the postoperative measurements will be masked. Surgeons are 
impossible to mask, due to the difference in (optical) design between both 
IOLs. All surgeries will be performed by experienced surgeons, performing >250 
cataract surgeries per year. Cataract extraction will be performed using either 
the conventional or Femtosecond-laser assisted cataract surgery, according to 
the preference of the surgeon.

The IOL power calculation will be performed according to the optical biometry 
assessment of the IOLMaster700 and the Barrett True K formula will be used 
among all participants, using the Barrett True K toric calculator. The surgeons 
will use their personalized lens constants for optimal results. The power 
calculation will be targeted on mini-monovision in all participants, for the 
dominant eye we choose an emmetropic target closest to zero, and the 
non-dominant eye a myopic target between -0.25 and -0.75D is selected. Eye 
dominance is determined using the Miles test (triangle test).

Patients will be examined pre-operatively and 1 week, and 1 and 3 months 
postoperatively. All patients will undergo delayed sequential bilateral 
cataract surgery (DSBCS) with the following post-operative examinations: one 
week after surgery of the first operated eye, one week after surgery of the 
second operated eye, and 1-, and 3-months postoperative visits at which both 
eyes will be examined in the same visit. Both eyes are examined simultaneously 
at 1, and 3 months postoperatively in order to minimize the number of 
postoperative follow-up visits for patients. Consequently, with DSBCS, at 1 
months postoperatively, the first eye will be 5 weeks after surgery and the 
second eye 3 weeks. At 3 months postoperatively, the first eye will be 13 weeks 
after surgery and the second eye 11 weeks. We assume that this time difference 
does not affect the results.

All patients will receive a standard cataract surgery on both eyes with the 
phacoemulsification technique. One group receives bilateral implanation with 
the Clareon  Vivity IOL (EDOF IOL - intervention-group) and the other group 
receives bilateral implanation with the Clareon  Monofocal IOL (Monofocal IOL 
- controlgroup). total of 48 patients will be randomized into either the 
intervention-group or the control-group at a 1:1 ratio.

In this study, all participants will receive their cataract surgery according 
to standard procedure. As with any type of intraocular surgery, there is a 
possbility of complications due to anesthesia, drug reactions, and surgical 
problems. Both Alcon Clareon Vivity and Clareon Monofocal IOLs, used in this study, are 
CE-marked and commercially available in the countries in which the study will 
be conducted.
Postoperatively, there will be one extra postoperative visit in addition to the 
standard cataract surgery follow-up. All additional measurements during this 
visit are non-invasive. And lastly, the participants will be asked to fill out 
questionnaires at 3 months posoperatively regarding patient satisfaction, 
quality of vision and spectacle independence. 
Postoperatively there may still be residual refractive errors leading to a 
suboptimal patient satisfaction. Laser-treatment or spectacles may be needed to 
correct these errors. In addition, optical disturbances (halos and glare) can 
occur postoperatively, but usually these become less apparent after 
neuroadaptation has taken place. According to the literature, EDOF and 
monofocal IOLs carry comparable risks for these optical disturbances after 
surgery. 
Enrolled patients will receive travel compensation during the last 
postoperative visit (19 cent per km). If participants travel by public 
transport, a full refund for these costs will be offered.