Ultrasound biomicroscopy in deep sclerectomy

To evaluate by ultrasound biomicroscopy (UBM) the anatomical characteristics and the intraocular pressure (IOP) lowering mechanisms of deep sclerectomy after long-term follow-up.

In all, 22 eyes of 21 consecutive patients who had deep sclerectomy were examined by UBM. Several UBM variables were prospectively evaluated, including the presence and maximum length and height of the intrascleral space, the minimum thickness of residual trabeculo-Descemet membrane (TDM), the presence and type of subconjunctival filtering bleb, and the presence of other possible drainage sites, for example suprachoroidal. Surgical success was considered to be achieved when the IOP was <22 mmHg and the IOP was lowered by more than 20% without the use of any medication. The possible association between UBM variables and the surgical outcome was determined.

The mean time between surgery and the UBM examination was 12.0+/-5.3 months. The mean IOP decreased significantly from a preoperative value of 23.7+/-4.0 to 16.0+/-3.9 mmHg at the time of UBM (P<0.01). There was a poor correlation between the level of IOP at the time of UBM and the length of intrascleral space (r2=0.0016), the height of the intrascleral space (r2=0.136), or the thickness of remaining TDM (r2=0.0009). The presence and type of filtering bleb were not associated with the success.

In patients undergoing deep sclerectomy, UBM examination after long-term follow-up showed the presence of an intrascleral space and a filtering bleb in most patients. The surgical outcome was not associated with the UBM variables of the surgical area.