Posterior Capsule Opacification Severity, Assessed with Straylight Measurement, as Main Indicator of Early Visual Function Deterioration

Abstract

To study the effect of posterior capsule opacification (PCO) morphology and severity on different aspects of visual function (VF): the small-angle domain (visual acuity [VA], contrast sensitivity [CS]) and large-angle domain (straylight; logarithm of the straylight parameter s [log{s}]). To evaluate whether straylight is a valuable additional indicator for appropriate posterior capsulotomy referral. Prospective, comparative study. For the study population, 240 pseudophakic eyes with PCO and a capsulotomy indication were selected. For the reference population, 99 pseudophakic eyes without PCO were selected. The relation between PCO morphology and PCO severity and the precapsulotomy and postcapsulotomy logarithm of the minimum angle of resolution (logMAR), logarithm of CS (log[CS]), and log(s) values were determined. The PCO severity was assessed with retroillumination using evaluation of posterior capsule opacification (EPCO) software. Precapsulotomy logMAR and log(s) values were used to predict functionally significant logMAR and log(s) improvement after capsulotomy. The logMAR, log(CS), and log(s) improvements of ≥0.20 log units were considered functionally significant (i.e., treatment effect). Precapsulotomy logMAR and log(s) values, above which a treatment effect (improvement≥0.20 log units) can be expected with ≥50% probability, were determined and called cutoff values. Postcapsulotomy VF improvement was related to precapsulotomy VF values: Postcapsulotomy improvement was largest in cases with substantially impaired precapsulotomy VF parameters. Visual function deterioration was related to PCO severity rather than PCO morphology. The PCO severity (EPCO score) assessed with retroillumination has a progressive, linear relation with log(s) and a curvilinear relation with logMAR. Reflected light examination is expected to overestimate functional PCO severity. The precapsulotomy cutoff value was ≥1.44 for log(s) and ≥0.21 for logMAR. The linear relation between retroillumination PCO severity and log(s) indicates that log(s) is sensitive to low PCO severity, whereas the curvilinear relation between PCO severity and logMAR indicates that logMAR is unaffected by low PCO severity. Straylight is a sensitive, additional indicator for capsulotomy referral, especially in less severe cases of PCO. In ophthalmic practice, the precapsulotomy log(s) cutoff value of 1.44 can be used as an indicator for beneficial capsulotomy referral. The author(s) have no proprietary or commercial interest in any materials discussed in this article.