Elimination of Posterior Capsule Opacification

In their influential 2001 study, “Eradication of Posterior Capsule Opacification: Documentation of a Marked Decrease in Nd:YAG Laser Posterior Capsulotomy Rates Noted in an Analysis of 5416 Pseudophakic Human Eyes Obtained Postmortem,” Apple et al1Apple D.J. Peng Q. Visessook N. et al.Eradication of posterior capsule opacification: documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem.Ophthalmology. 2001; 108: 505-518Abstract Full Text Full Text PDF PubMed Scopus (245) Google Scholar (see page S29) provided valuable insight into factors with bearing on the development of posterior capsule opacification (PCO) occurring after cataract surgery in a comparative autopsy tissue analysis of 5416 pseudophakic postmortem eyes collected between January 1988 and January 2000. Eyes studied had received 8 different intraocular lenses (IOLs) that were available in the United States, including rigid and foldable IOLs. The authors developed a computerized model that allowed them to predict trends or timelines of neodymium:yttrium–aluminum–garnet (Nd:YAG) laser rates for each IOL design, and they identified 6 factors related to surgical technique and IOL choice that seemed to influence PCO. Addressing these factors ultimately may well eradicate PCO, the second most common cause of reversible visual loss worldwide after cataract. The conclusions of these authors were that the older IOL designs show high rates of PCO and Nd:YAG laser treatment (between 20.3% and 33.4%), that the foldable IOLs were associated with lower Nd:YAG laser rates than rigid IOLs (14.1% vs. 31.1%, respectively), and that modern biomaterials like silicone and acrylic were associated with reduced Nd:YAG laser rates of 17.1% and 0.9%, respectively. They defined 6 factors influencing PCO: hydrodissection before phacoemulsification, in-the-bag fixation of the IOL, an appropriately sized anterior capsulorhexis, the use of highly biocompatible IOL biomaterial (hydrophobic acrylic seemed to behave better than silicone), optimal contact of the IOL optic and posterior capsule, and an IOL optic geometry with square, truncated edges. Between 2001 and 2019, these recommendations have been taken seriously by the industry and ophthalmologists worldwide, giving rise to new lens designs and biomaterials. The predictions by Apple et al regarding the hydrophobic acrylic turned out to be correct for early postoperative follow-up. However, a recent study of a German claims database suggests that the PCO rate after 4 years remains relatively high2Kossack N. Schindler C. Weinhold I. et al.German claims data analysis to assess impact of different intraocular lenses on posterior capsule opacification and related healthcare costs.Z Gesundh Wiss. 2018; 26: 80-90Crossref Scopus (17) Google Scholar: 31.7% for the hydrophobic IOLs compared with 56.6% for the hydrophilic IOLs and necessitating a still high rate of Nd:YAG laser capsulotomies. The use of a hydrophobic IOL reduced the healthcare cost of cataract surgery as a whole by 75% according to these authors. Recently, Ursell et al3Ursell P.G. Dhariwal M. Majirska K. et al.Three-year incidence of Nd-YAG capsulotomy and posterior capsule opacification and its relationship to monofocal acrylic IOL biomaterial: a UK real world evidence study.Eye (Lond). 2018; 32: 1579-1589Crossref PubMed Scopus (37) Google Scholar confirmed, in a total cohort of 52 126 eyes, the superiority of the hydrophobic IOLs over the hydrophilic IOLs when implanted in the bag. Can we take these conclusions for granted? When looking at longer-term follow-up results, Rönbeck and Kugelberg4Rönbeck M. Kugelberg M. Posterior capsule opacification with 3 intraocular lenses: 12-year prospective study.J Cataract Refract Surg. 2014; 40: 70-76Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar did not find any difference in PCO or overall survival of the capsule without capsulotomy 12 years after surgery when comparing acrylic IOLs and silicone IOLs. However, they did find a significantly higher PCO rate for rigid polymethyl methacrylate IOLs. To optimize the relationship between the IOL and the capsular bag, different devices have been proposed to standardize the anterior capsulorhexis. An historical overview of the anterior capsulotomy has been described beautifully by Packard.5Packard R. The evolution of the anterior capsulorhexis.in: Tassignon M.J. Ni Dhubhghaill S. Van Os L. Innovative Implantation Technique, Bag-in-the-lens Cataract Surgery. Springer Nature, Basel, Switzerland2019: 61-76Crossref Scopus (3) Google Scholar The effect of the most recently developed devices, that is, the Zepto (Mynosys Cellular Devices Inc, Freemont, CA) and CapsuLaser (EXCEL-LENS Inc, Livermore, CA), have not yet proven the superiority of a precisely calibrated anterior capsulorhexis compared with more variably sized manual capsulorhexis with regard to PCO prevention. These devices are not yet used routinely in daily cataract surgery to allow for conclusions to be drawn. When considering the importance of IOL geometry, it seems that the most critical issue is in the manufacture of square-edged IOL optics and haptics. Based on variability in the exact geometry of this edge from one lens to another and other variables that have not been studied under controlled conditions, the full effect of geometry on PCO prevention remains incompletely understood. Prediction of outcomes using mathematical models is extremely difficult because of the variability of the myriad parameters that influence posterior capsular opacification over time. Improvement in the surgical devices used to remove the lens material through a very small incision, using ultrasound or femtosecond laser technology, all likely contribute to PCO rates and must be incorporated into future predictive models. Modification of the variables studied by Apple et al in 2001 has proved to reduce rates of PCO substantially and to delay onset, but this postoperative complication has not yet been eliminated. Further modifications of lens design and surgical technique we hope will result ultimately in the eradication of PCO and the need for capsulotomy after cataract surgery. Eradication of Posterior Capsule Opacification: Documentation of a Marked Decrease in Nd:YAG Laser Posterior Capsulotomy Rates Noted in an Analysis of 5416 Pseudophakic Human Eyes Obtained PostmortemOphthalmologyVol. 127Issue 4Preview(1) To report the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy rate (%) of eight rigid and foldable intraocular lens (IOL) designs in a series of 5416 pseudophakic human eyes obtained postmortem, accessioned in our center between January 1988 and January 2000. (2) To identify factors that are instrumental in reducing the incidence of posterior capsule opacification, (PCO, secondary cataract) and hence the need for Nd:YAG laser posterior capsulotomy. Full-Text PDF Eradication of posterior capsule opacification: Documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortemOphthalmologyVol. 108Issue 3Preview(1) To report the neodymium:yttrium–aluminum–garnet (Nd:YAG) laser posterior capsulotomy rate (%) of eight rigid and foldable intraocular lens (IOL) designs in a series of 5416 pseudophakic human eyes obtained postmortem, accessioned in our center between January 1988 and January 2000. (2) To identify factors that are instrumental in reducing the incidence of posterior capsule opacification, (PCO, secondary cataract) and hence the need for Nd:YAG laser posterior capsulotomy. Full-Text PDF