Cataract and lens refractive surgery have reached a very high level of safety because of advances in technology used for lens extraction. Meanwhile, improvements in the accuracy of IOL power predictions and IOL technology continue to be a focus for improving surgical outcomes. Although the number of advanced technology IOLs continues to increase, for reasons of cost or issues related to ocular comorbidities, most patients choose or are only candidates for surgery with a monofocal IOL.
The aim of surgery with a monofocal IOL is to provide the targeted refractive outcome and clear vision that will be maintained over time. Selecting an implant that will meet these goals and the patient’s expectations should consider outcomes from bench testing and clinical research. According to available evidence, IOL material, optic design, including asphericity and edge profile, and haptic characteristics are all important factors influencing refractive predictability, postoperative visual quality, and long-term outcome stability. Then, from the surgeon’s perspective, IOL handling, delivery, and unfolding behavior are important because these characteristics impact operating room efficiency as well as safety.
We believe that all of these issues are well addressed with the CT LUCIA 621P, which is the latest entry from Carl Zeiss Meditec AG into the important market of monofocal IOLs. Made of a hydrophobic acrylic material with a heparin-coated surface, the CT LUCIA 621P is a modified aspheric (aberration-correcting) single-piece IOL with a 6.0 mm optic and overall length of 13.0 mm.
The CT LUCIA 621P has an aberration profile (ZO, Figure 6) that was engineered based on the realistic Liou-Brennan eye model and aims to create an ideal balance between aberration correction and aberration neutral effects. The central zone of the CT LUCIA 621P has negative spherical aberration to provide improved image quality by compensating for positive corneal aberration while there is positive spherical aberration in the periphery of the optic that confers increased tolerance to IOL decentration.
Figure 6. The aberration profile of the CT LUCIA621P has a non-uniform power distribution that provides an ideal balance between aberration correction and neutral effects.
As another feature, the CT LUCIA 621P has a 360° posterior square edge, which limits the development of posterior capsule opacification. In addition, it has long, step-vaulted C-loop haptics and a rigid optic-haptic junction that serve to maintain IOL positional stability and contact between the optic edge and posterior capsule.
The CT LUCIA 621P comes fully preloaded in the BLUESERT injector system that avoids unnecessary manipulation of the IOL and allows smooth and easy one-handed delivery of the IOL into the capsular bag (Figure 7).
Figure 7. Implantation of the fully preloaded CT LUCIA 621P. Video courtesy of Dr. Antonio Cuttitta
With its heparin-coated surface*, the CT LUCIA 621P unfolds in a controlled fashion that enables its positioning. All of these features add up to quick, safe, and easy implantation.
Proof of performance
To confirm our impressions about outcomes with the CT LUCIA 621P and support decisions to choose it for monofocal IOL cases, we conducted a prospective clinical study. In addition to recording and analyzing standard clinical and surgical data, we collected patient-reported outcome measurements (Cataract and Lens Ophthalmic Questionnaire = CLOQ) that reflect how well the surgery improved performance of routine daily tasks and its ability to meet the individual’s visual needs.
We enrolled patients undergoing cataract surgery who did not want a premium toric or presbyopia-correcting IOL and only excluded those with expected postop visual acuity worse than ≥0.40 logMAR. Our population included eyes with amblyopia (1), epiretinal membrane (1), cornea guttata (2), pseudoexfoliation (2), and glaucoma (4) as well as eyes with higher astigmatism. IOL power calculations were done with the IOLMaster 700 using the manufacturer’s A-constant (120.2) and the Haigis TK formula, which considers the anterior and posterior corneal curvature.
A total of 43 patients (median age 76 years) were enrolled in the study, and the total number of IOLs implanted was 65 (22 patients had a binocular procedure). Analyses of the postoperative refractive data showed no statistically significant difference comparing outcomes at 1 and 6 months after surgery. The stability of the refractive outcomes in our study corresponds with findings of a study conducted by Antonio Cuttitta, MD, who examined positional stability of the CT LUCIA 621P by measuring anterior chamber depth (ACD) with the IOLMaster 700.1 In the latter study, which included 60 eyes of 60 patients, there was no statistically significant difference comparing mean ACD at 1 week (5.36 mm) versus 1 month (5.34 mm). Subgroup analyses showed stability of ACD depth in both hyperopic and myopic eyes.
In our study, mean relative prediction error for spherical equivalent at 6 months was +0.16 D, and the absolute prediction error was ≤0.5D in 77% of eyes. It should be noted that our study group included eyes with astigmatism up to -4.25 D (median -0.75 D), and our results are from cases that represent our first experience with the CT LUCIA 621P and using the manufacturer’s A-constant. We are confident that we can improve the refractive accuracy in the future through constant optimization and recommend using the IOLcon A-constant value (119.7).
Mean monocular and binocular logMAR uncorrected distance visual acuity (UDVA) at 6 months was 0.10 and 0.05, respectively. LogMAR UDVA was between 0.04 and 0.15 for 95% of eyes and ranged from 0.00 to 0.10 for 95% of patients in binocular testing. LogMAR UDVA ≥0.2 was achieved by 78% of eyes, which is remarkable considering that almost half of the eyes operated on had significant astigmatism ranging from 0.7 to 4.25 D. Mean uncorrected near VA was ≤ 0.4 logMAR. These results are in good accordance with reported outcomes.1,2,3,4
Corresponding with the above clinical results, patient reported outcomes were very good. Ninety-three percent of patients were satisfied with the surgery and 87% reported no difficulties with uncorrected vision in daily life activities. Most patients indicated they were totally satisfied with their ability to perform common tasks (reading, watching TV, working at a computer, driving, recognizing faces and recognizing uneven surfaces). Only a single patient reported experiencing more than seldom difficulties with vision.
Some patients experienced photic phenomenon. Glare was reported more often than halo and starburst. However, most patients still experienced no more than seldom glare, and it is our impression that the occurrence of any of these visual symptoms was no different than that associated with other monofocal IOLs. In addition, when interpreting reports of glare after cataract surgery it is important to recognize that the potential for its development and its severity are affected by a variety patient-related factors, such as pupil size, dry eye, and cataract density.
Manufacturers of IOLs have continued in the quest to develop better lenses for presbyopia correction. However, the vast majority of patients who undergo cataract surgery are implanted with a monofocal IOL. For that reason, it is important for surgeons to be aware of the research and development that has occurred with this technology.
We found in our clinical reported outcome measurements that the CT LUCIA 621P monofocal IOL offers excellent UDVA at 6 months after surgery, and our patient reported outcome measurements show that it resulted in very high patient satisfaction. For all IOLs, personalization of lens constants is always recommended to achieve the best possible outcomes. We already modified the IOL constant for the CT LUCIA 621P based on the data we collected so far and will further refine the value as more outcomes are available.
* Fragment of heparin used in IOL surface coating with no pharmacological, immunological or metabolic action.
Part 1: Preparing for surgical success