Changes in macular thickness and depth of anterior chamber in patients after filtration surgery

The prospective study was undertaken to analyze retinal thickness of the macula and anterior chamber depth in patients undergoing filtration surgery at different times of follow-up.

Forty-four patients (45 eyes) were included. The thickness of the fovea and the extrafoveal retina were measured using optical coherence tomography (OCT). Anterior chamber depth was determined using the IOLMaster. All standard clinical examination and measurements were performed prior to surgery, at the 2nd day (1-3 days), 1 week, 1 month and 3 months after surgery.

Preoperative IOP under topical medication was 25.5+/-7.5 mmHg. IOP was significantly decreased at all postoperative visits ( P<0.0001): 10.8+/-5.9 mmHg at the 2nd day, 10.4+/-5.2 mmHg after 1 week, 11.7+/-4.4 mmHg after 1 month and 11.4+/-3.6 mmHg after 3 months. No patient in our study suffered from prolonged postoperative hypotony (IOP<5 mmHg). Foveal thickness at the 2nd day, 1 week and 1 month were elevated compared with baseline ( P<0.004). Macular thickness changed from 164+/-20 microm before surgery to 168+/-20 microm after 2 days, 170+/-21 microm after 1 week, 173+/-19 microm after 1 month and 165+/-16 microm after 3 months. Mean thickness of the extrafoveal retina did not change significantly. Also, there were no significant changes in anterior chamber depth. There was no significant correlation between reduction of IOP and retinal thickness or anterior chamber depth.

The reduction of IOP after filtration surgery leads to a moderate increase in foveal retinal thickness over approximately 1 month and is not associated with shallowing of the anterior chamber, provided that prolonged postoperative hypotony is avoided with the surgical technique used.