Imaging of trabeculectomy blebs with Visante anterior segment optical coherence tomography after digital ocular...

We investigated changes in intrableb morphology of functioning trabeculectomy blebs with anterior segment optical coherence tomography (AS-OCT) after digital ocular compression.

Sixty-eight patients who underwent fornix-based trabeculectomy were recruited from Seoul St. Mary's Hospital. Intraocular pressure (IOP) and AS-OCT images were taken before and after ocular compression. Bleb height and wall thickness and height and length of the internal cavity were measured by AS-OCT. The hyporeflective areas and number of microcysts were checked on both vertical and horizontal images. AS-OCT parameters for IOP change, bleb morphology, and interval between surgery and examination were compared.

Ocular compression yielded significant changes for all AS-OCT parameters other than maximum bleb wall thickness in the 6- to 12-month period after surgery. Correlation between IOP change and AS-OCT parameters was greatest for the horizontal and vertical length of the internal cavity (Spearman rank correlation coefficient ρ = 0.717, P < 0.0001, and ρ = 0.866, P < 0.0001, respectively). Response to ocular compression in cystic blebs was mainly enlargement of the internal cavity and increase in bleb height. However, in diffuse filtering blebs, increases in the size of the hyporeflective areas and the number of microcysts were the main findings. From 12 months postoperatively, changes in AS-OCT intrableb parameters were significantly reduced, showing no difference after ocular compression.

Digital ocular compression may be useful in maintaining bleb morphology when it is used for 6 months postoperatively. Response to ocular compression as assessed by bleb morphology was different.