Ocular Hypotony after Glaucoma Surgery

Background: Postoperative hypotony is associated with choroidal effusion, suprachoroidal haemorrhage, aqueous misdirection syndrome (malignant glaucoma), choroidal folds and hypotony maculopathy, anterior chamber (AC) shallowness or loss and subsequent failure of the original filtration of procedure. This work aimed to study the causes, risk factors, adverse effects, and management plans of ocular hypotony after different glaucoma surgeries. Methods: This retrospective study was carried out on 205 eyes underwent glaucoma surgery with follow up for more than 3 months. Patients were divided into two groups: 30 cases were diagnosed with post-operative hypotony, 175 eyes were without hypotony. Patients were subjected to glaucoma diagnosis, type of glaucoma operation and recorded IOP for 3 months at least. Results: CPC, Visco-Trab, Phaco Visco-Trab Visco and express valve were significantly different between the two groups (P=0.049, P=0.012, P=0.043 and P<0.001 respectively) and other types of operation were insignificantly different between the two groups. IOP was significantly decreased at first diagnosis of hypotony and at last follow up compared to before operation (P value <0.001). IOP at last follow up was significantly increased compared to first diagnosis of hypotony (P value <0.001). Criteria of hypotony eyes were insignificantly different between patients needed surgical intervention and no surgical intervention. Conclusions: Postoperative hypotony was most common in pseudo-exfoliative glaucoma cases compared to other glaucoma types. While the most type of glaucoma surgery that was associated with postoperative hypotony was viscocanalostomy combined with express shunt. The adverse effects reported in our study were choroidal effusion and hypotony maculopathy.