Early Macular Thickness Changes after Trabeculectomy and Combined Phaco-Trabeculectomy

To assess postoperative changes in central retinal thickness (RT) following trabeculectomy and combined phaco-trabeculectomy using spectral domain-optical coherence tomography.

In a prospective interventional comparative study, 64 consecutive glaucoma patients who underwent trabeculectomy (32 eyes) or phaco-trabeculectomy (32 eyes) were included. A macular thickness map using the Early Treatment Diabetic Retinopathy Study circles of 1 mm, 3 mm, and 6 mm was the standard to evaluate the 9-subfield thickness preoperatively and again at 1 and 3 months after surgery. Four subfields in each of the 3 mm and 6 mm rings were considered parafoveal and perifoveal regions, respectively.

Preoperative measurements were similar in the two groups, except patients in the combined group which were older (P = 0.002). The mean RT in the combined phaco-trabeculectomy group at month 1 was significantly higher than baseline measurements at central subfield retinal thickness (CSRT) (P = 0.01), temporal (P = 0.001), and inferior (P = 0.04) parafoveal and temporal (P = 0.01), superior (P = 0.02), and nasal (P < 0.001) perifoveal quadrants; however, RT changes in the trabeculectomy-only group were not statistically significant at months 1 and 3 (P > 0.05). The increase in the temporal perifoveal RT of the combined phaco-trabeculectomy group persisted at month 3 (P = 0.01), while the RT in other sectors returned to preoperative values. The two treatment groups did not differ in terms of changes in the CSRT over time (P = 0.37). In addition, no difference was observed between the treatment groups regarding the parafoveal RTs at each time points (0.06 ≤ P ≤ 0.29).

There was no significant difference in the pattern of changes of CSRT and parafoveal RT between trabeculectomy and combined phaco-trabeculectomy treatment groups up to 3 months after surgery. Some detectable increase in RT in the combined phaco-trabeculectomy will reverse to baseline values 3 months after surgery, except in the temporal perifoveal region.