This activity is produced by SLACK Incorporated and sponsored by Alcon.
Robert Lehmann, MD, FACS
Lehmann Eye Center
A notable achievement in IOL technology is the Alcon AcrySof IQ IOL platform. Its proven performance provides cataract treatment and, due to its proprietary BioMaterial, the AcrySof IQ IOL offers high capsular adhesion rates, decreased incidence of Nd:YAG laser treatments and reduced incidence of glistenings.1,2
Robert Lehmann, MD, FACS, discusses his clinical experience with the AcrySof IQ IOL.
Capsular adhesion is important because the surface of an IOL should maintain a strong bond with the existing fibronectin protein structure on the capsular bag in order for the lens to stay in place.3 Fibronectin, a glycoprotein present in human serum and blood aqueous barrier around the eye, acts as an adhesive that binds the IOL to the capsule. Furthermore, fibronectin’s natural properties help stabilize the lens in the capsular bag postoperatively. In theory, the greater the amount of fibronectin bound to an IOL, the greater the likelihood that the IOL will adhere to the capsule more efficiently.3
AcrySof IQ IOLs are made of a copolymer of phenylethyl acrylate and phenylethyl methacrylate, cross-linked with butanediol diacrylate. The AcrySof material has been shown in in vitro studies to have the highest levels of fibronectin bioadhesion.2
Although it is a procedure that has a proven track record, there are risks associated with Nd:YAG posterior capsulotomy, including cystoid macular edema, retinal detachment and increased intraocular pressure.4
Overall a lower percentage of patients receiving the AcrySof IQ IOL required Nd:YAG laser treatment after cataract surgery.5
Glistenings, or microvacuoles, are tiny inclusions of water present after implantation of an IOL. The presence of glistenings in lens material has been noted in almost all IOL materials, including PMMA, silicone and hydrophobic acrylic.1 Glistening formation relies partially on the water absorption rate of IOL material, and for hydrophobic IOLs, the rate is less than 1%. According to Werner, absorbed water is not typically visible because it is present in the polymer architecture as water vapor.6 However, if the water vapor collects in a void within the polymer network, a visible water drop forms. Additionally, since the refractive index of water droplets (1.33) is significantly different than that of the IOL polymer (1.55 for AcrySof IOLs), light is refracted and scattered, which can create a sparkling appearance — hence the term 'glistenings.'6
AcrySof IOLs manufactured in 2012 demonstrated a decrease in glistening severity, compared to IOLs manufactured in 2003.1 Although further study is needed, recent evaluations of glistening formations within hydrophobic IOLs indicate that there are continual improvements in reducing or eradicating glistenings altogether.
Mutlu Karakelle, PhD, provides invaluable insight on AcrySof's BioMaterials as the former head of IOL research at Alcon, and the pioneer behind the development of the AcrySof IQ IOL.
A large body of peer-reviewed literature demonstrates that glistenings do not adversely affect visual function, as measured using best-corrected visual acuity, contrast sensitivity, glare testing or wavefront measurements in human eyes. Glistenings also appear to have no measureable effect on lens optics when measured in a laboratory setting.7
AcrySof IQ monofocal IOLs were evaluated in the control arm of a clinical study to evaluate the effectiveness of an investigational IOL. The investigators reported any observations on the IOL, such as debris, glistenings on the IOL or forcep marks on the lens surface, among other observations noted at postoperative visits.8
At the final study visit, which occurred 4-6 months post-implantation, 96.3% of AcrySof IQ monofocal IOL patients had no observations of glistenings in the first implanted eye, and 95.6% of AcrySof IQ monofocal IOL patients had no observations of glistenings in the second implanted eye.8
The modern day cataract surgeon must possess a good understanding of all IOL materials to select the right IOL for every patient. IOL choice impacts the techniques and tools that the surgeon will use, and can reduce the risk of complications that may compromise the patient’s visual outcomes. The BioMaterial characteristics of the AcrySof IQ IOL platform are a good choice for promoting clear capsules postoperatively.
Dr. Lehmann is a paid consultant for Alcon.
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