Examining stability of aspheric IOL in cataract patients

Special to Ophthalmology Times®

Patients who wish to reduce their reliance on glasses have high expectations for visual outcomes after cataract surgery.

To meet their demands, lens technology has advanced significantly, particularly with the introduction of aspheric IOLs, which are designed to reproduce the natural shape of the crystalline lens to improve visual quality and contrast sensitivity.¹

To achieve the best visual outcomes from advanced lens technology, lens stability in the capsular bag is essential.

I recently studied the anterior chamber stability of the newly introduced CT Lucia 621P (Carl Zeiss Meditec), a monofocal aspheric hydrophobic acrylic IOL with a heparin-coated surface (Figure 1).

Related: Curvature-changing IOL: New frontier in cataract and presbyopia surgeries

It is important to know the patient’s anterior chamber depth before surgery, which allows us to calculate the IOL power accurately. After surgery, it helps us determine the stability of the IOL in the capsular bag and assess the patient’s refractive outcome.

Lens design
The bi-sign design of CT Lucia IOLs compensates for a number of aberrations resulting from IOL misalignment or the corneal contour, providing the benefits of neutral and correcting aspheric IOLs and improving retinal image quality.²

The single-piece C-loop CT Lucia 621P follows the previously introduced monofocal spherical CT Lucia 211P and aspheric 611P(Y), in addition to other Zeiss monofocal IOLs.

It has a 6-mm-diameter optic and 13-mm total diameter and is available from +0.0 to +34.0 D in 0.5-D increments.

Related: Light-adjustable IOL offers positive refractive results in patients

The lens has step-vaulted haptics and a reinforced optic-haptic junction to promote stability in the capsular bag, for improved lens centration, refractive predictability, and long-term visual outcomes.

The use of the injector is a key consideration for surgeons and surgical staff. This lens comes fully preloaded in a redesigned injection system that makes injection easier, faster, and safer than before.

As the injector is advanced to the intermediate position, there is an audible click. The ramp stop helps the surgeon apply the correct pressure to the thumb flange to release the IOL.

Assessing lens stability
Within a 1-month period, I implanted this monofocal lens in 60 eyes of 60 patients aged from 51 to 91 years. It was used in every patient having cataract surgery; there were no specific inclusion or exclusion criteria.

Related: Early clinical experience with next-generation lens

Therefore, this protocol reflected our daily experience as cataract surgeons in performing routine cataract surgery with monofocal IOLs and demonstrated the typical clinical behavior of the IOL in this setting.

I examined the stability of the IOL by measuring anterior chamber depth with biometry (IOLMaster 700; Carl Zeiss Meditec). Preoperatively, the mean anterior chamber depth was 3.13 mm.

After surgery, the anterior chamber depth was measured twice: after 1 week and then 1 month later.

Anterior chamber depth measurements indicated good stability within the capsular bag, without the IOL position changing significantly, whether patients were hyperopic or myopic.

At 1 week, the mean anterior chamber depth was 5.36 mm and at 1 month it was 5.34 mm.

No patients had complications, nor did they report glare or other light-related disturbances.

Related: Small-aperture single-piece IOL could fill unmet need in patients

They had very good refractive outcomes that were consistent with the expected calculations of the biometer, indicating that the lens was very stable in the bag from the first week after surgery. The mean corrected visual acuity was 10/10.

The injector system was very easy to use and performed well with the 60 lenses we implanted. One lens got stuck in the injector, but this was remedied and otherwise we had no issues.

The learning curve was very easy; our experience was reproducible, and we demonstrated good reliability.

The IOL opens very quickly when injected and there were no problems with the optics. When the manufacturer questioned surgeons and nurses about the system, most reported that they preferred it over their reusable injector of choice.³

Surgical pearls
Based on my experience with the CT Lucia 621P, I would like to offer some advice for implanting it.

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It also is very important to use the correct amount of viscoelastic during the procedure to help the IOL slide across the injector and unfold correctly in the capsular bag.

If too much viscoelastic is used, the lens will slide across the injector but open slowly in the capsular bag because the haptic will stick to the plate of the lens.

In contrast, if there is not enough viscoelastic, the lens will not slide across the injector properly and a haptic may break.

It is also necessary in general to be especially careful with higher-power lenses because they are thicker and a bit more rigid. However, we did not have problems with higher-power versions of this lens.

Related: Haptic flanging reduces IOL dislocations after cataract surgery

Conclusion
In my experience, the CT Lucia 621P maintained stability in the capsular bag 1 week and 1 month after implantation and provided good refractive outcomes.

The redesigned injector system was easy to use and provided smooth delivery of the IOL into the capsular bag.

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Antonino Cuttitta, MD
e:studiooculisticocuttitta@gmail.com
Cuttitta is head of ophthalmology at Clinica Andros in Palermo, Italy. He has no financial disclosures related to this article.

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References
1. Schuster AK, Tesarz J, Vossmerbaeumer U. The impact on vision of aspheric to spherical monofocal intraocular lenses in cataract surgery: a systematic review with meta-analysis. Ophthalmology. 2013;120(11):2166-2175. doi:10.1016/j.ophtha.2013.04.011

2. Portney V. New bi-sign aspheric IOL and its application. Optom Vis Sci. 2012;89(1):80-89. doi:10.1097/OPX.0b013e3182376ba8

3. Carl Zeiss Meditec. CT LUCIA 621P. Surgeon evaluation report (April to September 2019). Report on surgery performance of CT LUCIA 621P injector.