BLOG: To YAG or not to YAG? Dealing with PCO and ACO
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When to perform a Nd:YAG capsulotomy for correction of posterior capsular opacification is an age-old question. Early capsulotomy can provide better visual quality and a happier patient — unless you are going to need to perform an IOL exchange, in which case you’d rather have that posterior capsule intact.
This has always been a conundrum. It stands to reason that the advanced optical designs in today’s presbyopia-correcting IOLs might make patients even more sensitive to PCO, justifying earlier intervention. It also makes sense that capsular folds or opacification would have an impact on vision, given what we know about the need for a clear optical pathway in order to achieve optimal visual performance with presbyopia-correcting IOLs.
Using double-pass retinal imaging (HD Analyzer, Visiometrics), we assessed the impact of PCO on retinal image quality before and after Nd:YAG capsulotomy in 26 pseudophakic eyes.
After Nd:YAG capsulotomy, there were statistically significant improvements in corrected distance visual acuity (CDVA, P = .007), objective scatter index (OSI, P = .001), modulation transfer function cutoff frequency (P = .001) and Strehl ratio (P = .020).
Even in a subgroup of 10 eyes with pre-Nd:YAG CDVA of 0.10 logMAR (20/25) or better, there was a 35% decrease in light scatter. Many people would assume that a 20/20 eye is unaffected by PCO, but in addition to the improvements in OSI after Nd:YAG capsulotomy, we also saw the visual acuity in some eyes improve to 20/16 or 20/12. We believe that capsular opacification in general is a leading factor affecting the elusive effective lens position, and earlier intervention may mean earlier relative stabilization.
As a result of our findings, we routinely screen for symptoms of capsular opacification with early clinical findings. More and more, this leads to earlier capsulotomy in order to achieve more LASIK-like outcomes for our refractive cataract patients.
Anterior chamber opacification is less common than PCO; however, in severe cases it may be more problematic because it can more adversely affect lens position, particularly in patients with zonulopathy. Like PCO, optical design may affect ACO. A major advantage of the Tecnis IOL platform (Johnson & Johnson Vision), in my opinion, is that it has a very low propensity to form ACO or capsular contraction syndrome. The design seems to protect the capsule from lens epithelial cell proliferation, as this interesting film festival video from the 2017 ASCRS meeting explores.
Prevention of ACO and early intervention in cases of PCO can contribute to stabilization of effective lens position. By avoiding ACO, one can potentially reduce internal coma and allow for maintenance of proper IOL centration, which is particularly important with diffractive IOL technology and/or eyes at greater risk of decentration due to zonulopathy. Lens designs that accomplish this goal can help patients maintain clear capsules and enjoy vibrant vision for many years after cataract surgery.
References:
Chang DH, et al. Am J Ophthalmol. 2014;doi:10.1016/j.ajo.2014.06.028.
Hartman M, et al. Clin Ophthalmol. 2018;doi:10.2147/OPTH.S172251.
Kahraman G, et al. Br J Ophthalmol. 2014;doi:10.1136/bjophthalmol-2013-303841.
McMillin JC, et al. Arq Bras Oftalmol. 2019;doi:10.5935/0004-2749.20190039.
Disclosure: Waring reports he is a consultant for Johnson & Johnson Vision and a member of the Johnson & Johnson Vision optics advisory board.