Assessment of retinal function before and after idiopathic macular hole surgery

Purpose: To evaluate preoperative and postoperative retinal function in patients who underwent macular surgery for idiopathic macular hole.

Design: Prospective, comparative, interventional case series.

Methods: Thirty eyes of 30 patients with idiopathic macular hole were included in the study. Patients underwent pars plana vitrectomy and peeling of the internal limiting membrane (ILM). ILM visualization was improved in 15 patients by using triamcinolone acetonide and in the remaining 15 patients by using infracyanine green dye. Spectral-domain optical coherence tomography examination was performed to document macular hole closure. Retinal function was assessed preoperatively and postoperatively over a period of 12 months by best-corrected visual acuity (BCVA) measurement (ETDRS chart), MP-1 microperimetry, and focal electroretinogram recording (fERG). Focal electroretinograms were recorded in response to a sinusoidally modulated (41 Hz), uniform field presented to the macular (18 degrees) and foveal (2.25 degrees) region.

Results: Macular hole closure was achieved in all patients in both groups. At 12 months, visual acuity improved in both groups (P < .001), and there were no statistically significant differences between groups. Mean macular sensitivity within the central 2 and 8 degrees increased in both groups, and there were no statistically significant differences between groups at any follow-up. In the triamcinolone acetonide group, 12 months after surgery the amplitude of the fERG's first harmonic (1F) increased both in the macular region (P < .001) and in the foveal region (P < .05). In the infracyanine green group, at 12 months the amplitude of the first harmonic (1F) decreased in both areas. The decrease was significant in the macular region (P < .05) and not significant in the foveal region (P = .095).

Conclusion: Vitrectomy and ILM peeling assisted with either triamcinolone acetonide or infracyanine green staining improves visual acuity and mean macular sensitivity at 12 months in patients affected by idiopathic macular hole. However, triamcinolone acetonide staining is associated with an increase of fERG's first harmonic amplitude in the foveal and macular region, whereas in the case of infracyanine green staining it seems to decrease after surgery. The reduction of the amplitude of fERG's first harmonic suggests that infracyanine green may have a late toxic effect on photoreceptor cells.