Relationship between corneal biomechanical properties and optic nerve head changes after deep sclerectomy.

PURPOSE: To evaluate corneal biomechanical properties and optic nerve head (ONH) changes following deep sclerectomy (DS) and the relation to each other. METHODS: Forty-nine eyes with primary open-angle glaucoma that underwent DS were studied. Corneal biomechanical properties were assessed using the Ocular Response Analyzer and the ONH was evaluated by Spectralis optical coherence tomography with enhanced depth imaging technology before surgery and 3 months postoperatively. Changes in corneal hysteresis (CH), corneal resistance factor (CRF), optic nerve cupping, prelaminar tissue thickness, and lamina cribrosa depth and thickness were registered. A correlation matrix and multiple linear regression models were used to determine predictors of ONH changes. RESULTS: At 3 months after surgery, mean corneal compensated intraocular pressure (IOPcc) significantly decreased by 27.9% (p<00.001) and mean Goldmann-correlated IOP (IOPg) decreased by 30.52% (p<00.001). Mean CH increased and CRF decreased by 18.4% and 10.1%, respectively (p<00.001). There was a significant reversal of ONH cupping mainly due to a prelaminar tissue thickening (p<00.001). Significant associations were found between ONH cupping reversal and prelaminar tissue thickening with preoperative IOPcc (p = 0.046), IOPg (p = 0.02), and CRF (p = 0.002) and with changes in IOP, CH, and CRF (p<00.001, p = 0.004, p = 0.018, respectively) after surgery. CONCLUSIONS: Corneal hysteresis increased and CRF decreased significantly 3 months after DS. Corneal resistance factor was the single largest preoperative factor influencing cupping reversal changes. Despite the influence of preoperative variables, postoperative IOP reduction was the only independent factor influencing changes observed in the ONH after surgery.

Comparison of lidocaine 2% gel versus retrobulbar anaesthesia for implantation of Ahmed glaucoma drainage.

PURPOSE: To compare patient comfort and the efficacy of lidocaine 2% gel versus retrobulbar anaesthesia for Ahmed glaucoma implant surgery. PATIENTS AND METHODS: This prospective study included 32 eyes of 32 patients scheduled to undergo implantation of an Ahmed glaucoma drainage device for refractory glaucoma in one institution, randomized to receive either topical lidocaine 2% gel or retrobulbar anaesthesia. Sixteen eyes were randomized to each group. Patient assessment of pain was recorded during delivery of anaesthesia, during surgery and after surgery, using a visual analogue pain scale. The need for additional anaesthesia during tissue manipulation was recorded. Surgeon assessments of operative conditions, patient co-operation and intraoperative complications were also recorded. RESULTS: The patients in the retrobulbar group reported significantly more discomfort during administration of the anaesthetic agent than the patients in the topical anaesthesia group (p = 0.000). There was no significant difference in patient-reported pain scores intraoperatively (p = 0.317) or postoperatively (p = 0.875). Surgeon assessment showed similar levels of patient co-operation in both groups (p = 0.615). The overall operating conditions were overwhelmingly positive in each group (p = 0.186). The mean duration of surgery was significantly longer in the topical group compared with the retrobulbar group (p = 0.049). CONCLUSIONS: Lidocaine 2% gel is a safe alternative to retrobulbar anaesthesia for Ahmed drainage implant surgery and avoids the significantly greater pain associated with the administration of retrobulbar anaesthesia. It provides a reasonably safe and comfortable surgical environment and is well tolerated by patients.