The degree of postoperative filtering bleb scarring is an important factor that determines the success or failure of trabeculectomy. The combined use of antimetabolites for suppressing scarring dramatically increased success rates; however, there are currently no methods to quantitatively evaluate scarring. Although severely scarred filtering blebs can be assessed by slit-lamp microscopy, it is essential to detect the signs of early scarring. The qualitative characteristics of the interior of the filtering bleb cannot be assessed with normal anterior segment optical coherence tomography (OCT). In principle, we developed a new-generation polarization-sensitive OCT that can visualize scarring within the tissue. In filtering blebs with decreased function, the polarization phase difference increased and internal scarring was confirmed; however, this was limited to qualitative assessment, and investigating detailed early postoperative changes was difficult. Thus, herein, we quantified the polarization phase difference to analyze post-trabeculectomy scarring changes quantitatively and over time. There was no increase in the polarization phase difference up to the second postoperative week; however, this had significantly increased at 1 month postoperatively. Of the cases with increased polarization phase difference at 1 month postoperatively, 55.6% cases had a decreased filtering bleb function, whereas among cases in which the polarization phase difference had not increased at 1 month postoperatively, only 7.7% cases had a decreased filtering bleb function. Detecting increased polarization phase difference in the early postoperative period was thus suggested to be an effective predictor of subsequent filtering bleb function. This paper reviewed the history of imaging of filtering blebs by anterior segment OCT and the new-generation polarization-sensitive OCT. It also investigated and summarized the relationships with clinical findings, including polarization OCT, and predicted the prognosis of filtering bleb function.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 122: 851-858, 2018.