Abstract
Purpose: :
To describe the microstructural findings of filtering blebs using non-contact confocal in vivo microscopy and to correlate these with the clinical features.
Methods: :
Forty blebs of 32 patients ranging in duration from several months to fifteen years after trabeculectomy underwent non-contact in vivo confocal microscopy using the Heidelberg Retina Tomograph Rostock Cornea Module (50x non-contact Nikon lens, 1 µm resolution, field of vision: 300 x 300 µm, Heidelberg Engineering, Germany). Blebs were clinically classified as: low diffuse and hypovascular (14), elevated, domed and encapsulated (17), and cicatrized non-filtering, and flat (9). Multiple sequence images were taken over the flap at 1.5-2 mm from the limbus. All images were analyzed and compared with the clinical findings.
Results: :
Sequence images of all diffuse blebs showed small to medium size epithelial and stromal cystic spaces with scattered hyperreflective collagen-like networks. Elevated, encapsulated blebs revealed medium to large size stromal cystic spaces surrounded by hyperreflective connective tissue walls. Flat blebs showed diffuse hyperreflective dense stroma, increased vascularization, and no cystic spaces. The microscopic findings of all blebs correlated with the clinical morphology and are consistent with previous reports of contact confocal microscopy. The quality of the images of the epithelial layer was lower than those obtained with contact methods because of strong surface reflections and lack of gel use to balance refractive index differences.
Conclusions: :
The non-contact in vivo confocal microscopy avoids potential changes in bleb anatomy and reduces the risk of bleb microinjuries, leaks, and infections especially in thin-walled blebs. It is preferred in the early postoperative period after filtering surgery where unnecessary contact to the bleb should be avoided. This promising non-contact approach needs to be further studied and optimized for imaging surface tissues in order to improve our understanding of the healing stages of filtering surgery.
Keywords: wound healing • imaging/image analysis: clinical • microscopy: confocal/tunneling