Abstract
Purpose: :
To correlate clinical bleb function with characteristics as detected by confocal in–vivo microscopy.
Methods: :
In a case–matched, cross–sectional study, 52 eyes of 48 patients were analysed one day to 12,8 years after trabeculectomy (median 36.5 days). Twenty–six eyes with a bleb clinically graded as failing were matched with 26 eyes graded as functioning in pairs of a comparable time after surgery. In both groups 9 "early blebs" (examination within the first 7 postoperative days) were distinguished from 17 "late blebs" (examination anytime after the 7th day). Function was graded clinically according to IOP and Wuerzburg filtering bleb classification score (Picht and Grehn). The patients were examined by slit–lamp and by confocal in–vivo microscopy (Rostock Cornea Module/HRT II, Heidelberg Engineering Inc., Germany). Stromal fiber patterns, the number of epithelial and stromal cystic spaces, and the amount of cellular infiltrates were evaluated in the superficial 40 microns of the central bleb.
Results: :
Cystic spaces were found in the epithelium and in the stroma. Epithelial cysts were associated with good function in late blebs (15/17 vs. 7/17 in failure), while they were equally distributed in early blebs (6/9 in both groups). In contrast, stromal cysts suggest a good function in early blebs (6/9 vs. 3/9), while in late blebs the number was similar in both groups (good function 10/17 vs. failure 11/17). Of the 4 stromal patterns (trabecular, reticular, corrugated, compacted) invisible to slit–lamp biomicroscopy, the trabecular pattern occured only in functioning blebs (8/26), particularly in early functioning blebs (5/9). In failing blebs, the corrugated pattern predominated. In functioning as well as in failing early and late blebs we found intraepithelial and stromal round cell infiltrates.
Conclusions: :
Confocal in–vivo microscopy allows to assess bleb structures that are invisible biomicroscopically. Morphologic features detected with this technique may characterize the bleb concerning time after surgery and function. The predictive value of these features deserves further clarification in a prospective longitudinal study.
Keywords: imaging/image analysis: clinical • wound healing • conjunctiva