Comparison of methods to quantify posterior capsule opacification using forward and backward light scattering
Nino Hirnschall1, Alja Crnej1, Vinod Gangwani1
1From Moorfields Eye Hospital NHS Foundation Trust (Hirnschall, Crnej, Gangwani, Findl), London, United Kingdom; the Department of Ophthalmology (Hirnschall, Findl), Vienna Institute for Research in Ocular Surgery, a Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria.
Purpose:
To compare forward and backward light scattering measurements to quantify posterior capsule opacification (PCO).
Setting:
Vienna Institute for Research in Ocular Surgery, Vienna, Austria.
Design:
Prospective single-center study.
Methods:
This observational study comprised consecutive patients scheduled for neodymium:YAG (Nd:YAG) capsulotomy for regeneratory PCO. The corrected distance visual acuity (CDVA) using Early Treatment of Diabetic Retinopathy Study charts and the contrast sensitivity under mesopic and photopic conditions using Pelli-Robson charts were assessed before an Nd:YAG capsulotomy was performed. Retroillumination images, rotating Scheimpflug scans (Pentacam HR), and straylight meter (C-Quant) and point-spread function (PSF) meter (Optical Quality Analysis System) measurements were performed before and after Nd:YAG capsulotomy.
Results:
The study enrolled 50 eyes of 50 patients. The mean uncorrected distance visual acuity and CDVA were 0.76 logMAR ± 0.18 (SD) and 0.68 ± 0.2 logMAR, respectively. The mean log contrast sensitivity (logCS) was 1.2 ± 0.15 logCS under photopic conditions and 1.05 ± 0.15 logCS under mesopic conditions. There was a moderate correlation between the Scheimpflug score and the Automated Quantification of After-Cataract score (r(2) = 0.37, P=.03). Furthermore, a moderate and close to significant correlation between the PSF meter and the straylight meter was observed (r(2) = 0.32; P=.07).
Conclusion:
Each of the 4 devices assesses different aspects of a patient's quality of vision. Further developments should focus on methods that measure forward scatter of light in a large visual angle and are not too patient or examiner dependent.
