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IOL technology’s leaps and bounds

It’s come a long way in a short time.

When Sir Harold Ridley developed and implanted the first IOL in a cataract patient some 65 years ago, his accomplishment was critical: Physicians now had a tool and method to restore the clarity of their patients’ vision.

But his accomplishment also created an IOL template that ophthalmic innovators would use to devise and advance the field now known as refractive surgery.

Considering that cataract surgery is the most common surgical procedure performed in the United States, with an estimated three million plus performed yearly in this country alone, Dr. Ridley’s advancement would have been monumental without the technology side of the accomplishment. But it surpassed even monumental because of the technological world it helped create: not only IOLs, but the tools to make the patient’s vision as close to perfect (if not perfect) as possible: aberrometers, lasers, microkeratomes, cross-linking.

What follows are some of the most important advances I have seen since becoming a surgeon 19 years ago.

HISTORY REVIEW

It was not until the early 1980s that the FDA approved the implantation of intraocular lenses at the time of cataract surgery, and these were anterior chamber models. Foldable IOLs were subsequently developed, which enabled the surgeon to perform through a much smaller incision.

As technology has advanced, surgeons have had reduced intra- and post-operative complications, and concomitantly brought about a significant improvement in the quality of outcomes.

THE ASPHERIC SOLUTION

Aspheric intraocular lenses have been developed to help reduce overall positive spherical aberration postoperatively. In 2009 Advanced Medical Optics’ Tecnis (now owned by Johnson & Johnson Vision) gave U.S. surgeons the first negative spherical aberration lens based on research that demonstrated an average value of +0.27 um of positive spherical aberration in the human optical system.1,2 Since that time, various lenses have been marketed with different degrees of asphericity, including ones with zero spherical aberration. Zero aberration lenses are particularly helpful in patients undergoing cataract surgery with irregular corneas. It has been theorized that the surgeon can obtain preoperative measurements to determine a patient’s corneal spherical aberration. Then he can subsequently pick the appropriate IOL to match that individual’s optical system and create an overall spherical aberration of zero.

In my practice

I find that achieving target refractive outcomes is the single most important factor for a successful outcome. I therefore tend to utilize a lens for which I have significant experience, and I constantly personalize my biometry to ensure an ideal outcome. In the specific situation when I expect a high chance of decentration, I will choose a zero-aberration implant, as these will induce minimal spherical aberration even when they are not perfectly centered.

ADDRESSING ASTIGMATISM

Correction of astigmatism has enabled surgeons to offer excellent options to their patients who wish to reduce or eliminate their need for spectacles. Toric IOLs have proven to be a safe and reliable alternative to monofocal implants in patients with a greater than 1.0 diopter of corneal astigmatism. In this country, there are two monofocals, one accommodating, one multifocal, and one extended-depth-of focus-toric that are approved. There are very few contraindications to placing this type of technology.

In my practice

Astigmatism reduction is routinely offered to all patients during the surgical consultation. In patients who have less than 1.0–1.25 diopters of astigmatism, femtosecond laser is offered to reduce these smaller amounts. In patients with greater than 1.25 diopters of astigmatism, the toric implant is discussed as the best option (Figure 1). Preoperative irregular astigmatism that is neutralized with hard contact lenses, such as in advanced keratoconus patients or those individuals who have had prior penetrating keratoplasty, is best left alone. It is explained to these patients that they are simply poor candidates for the technology. Preoperative counseling, realistic expectations and accurate biometry are the keys to success with these types of implants.

Figure 1. Toric IOL immediately after implantation.

ADDRESSING PRESBYOPIA

Presbyopia-correcting IOLs have provided the ophthalmology community with another excellent option to reduce spectacle dependence. The original products available for U.S. surgeons, multifocal intraocular lenses (MFIOLs), originally did not have toric options. Depending on which model is utilized, refractive and diffractive optics tend to permit the patient to see not only distance, but intermediate and near as well (Figures 2 and 3). Most models now come with varying degrees of magnification or presbyopia correction. This enables the surgeon to determine with the patient preoperatively what is the priority and then attempt to correct for it with the appropriate type of implant.

Figure 2. Multifocal IOL immediately after implantation.

Figure 3. Another view of the multifocal IOL.

Careful preoperative screening is important to eliminate noncandidates for the technology. The ocular surface and overall corneal quality must be thoroughly examined. The optic nerve and macula have to be screened for disease. If the eye appears healthy, then the patient is still considered for the technology. The overall personality of the patient has to be analyzed as well. Visually astute individuals may not be the best candidates. Engineers, designers, photographers and people with a discernable eye should be approached with caution, as they may not tolerate the nuances with their vision postoperatively.

In my practice

I have a thorough discussion with the patient about the technology and most importantly, I comprehensively discuss the drawbacks. I have found that under-promising results is much more important than guaranteeing outcomes to ensure a successful post-operative relationship with the patient.

When I do proceed with MFIOLs I place a low add in the dominant eye, and a medium add in the nondominant eye. I find this gives an excellent range of vision that patients tolerate extremely well.

The AcrySof IQ ReSTOR +2.5 D and the +3.0 D Multifocal Toric IOLs (Alcon) have enabled surgeons to include entire groups of people that were previously thought to be noncandidates, namely patients with mild to moderate amounts of corneal astigmatism. The early results have similar side effect profiles to those of regular multifocal implants.

CONCLUSION

Traditionalists will argue that cataract surgery was developed to restore the quality of vision to a compromised optical system, and they are 100% correct. But I have found that embracing new technology has helped to grow my practice and moreover, patients tend to value physicians and surgeons who constantly change and adapt to provide the highest level of technology and care.

If the next 65 years in our field are anything like the last six decades plus, physicians won’t have much of a choice. OM

REFERENCES

  1. Guirao A, Gonzalez C, Redondo M, et al. Average optical performance of the human eye as a function of age in a normal population. Invest Ophthalmol Vis Sci. 1999;40:203-213.
  2. Holladay, JT, Piers PA, Koranyi G, et al. A new intraocular lens design to reduce spherical aberration of pseudophakic eyes. J Refract Surg. 2002;18:683-691.
  3. Siedlecki D, Jozwik A, Zaja M, Hill-Bator A, Turno-Krecicka A. In vivo longitudinal chromatic aberration of pseudophakic eyes. Optom Vis Sci. 2014; 91:240-246.
  4. Siedlecki D, Ginis HS. On the longitudinal chromatic aberration of the intraocular lenses. Optom Vis Sci. 2007; 84:984-989.

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