Assessment of Possible Toxic Effect of Indocianine Dye Applied in Macular Hole Surgery

Abstract

Abstract: : Purpose: To evaluate the change in macular function as a result of successful macular hole surgery (internal limiting membrane /ILM/ removal with and without indocyanine green /ICG/ staining) in cases of idiopathic macular holes and to assess the possible toxic effect of the dye applied. The only objective functional method to prove the possible toxicity of the dye is multifocal electroretinography (mfERG). Patients and methods: 27 eyes of 23 patients underwent macular hole surgery. In 16 eyes – Group A – ICG staining was used for visualisation of the membrane. In 11 eyes – Group B – no dye was applied. The pre, –and postoperative (3, 6, 10 and 20 months) examination protocol included: visual acuity (VA), slit lamp biomicroscopy and multifocal electroretinography (mfERG). The mfERGs (FOK) were obtained binocularly, by using the equipment "RETIscan" of Roland Consult. The central 30° (radius) of the retina was stimulated by 61 hexagons. "ERG jet" was used as a different electrode. In both groups response density (RD) of b–wave in the 2 central area was evaluated. Results: The macular hole closed in all patients. VA significantly improved in both groups compared to baseline. The improvement was more pronounced in Group B (p=0.015) then in Group A (p=0.039) after 20 months. (VA was better in Group B compared to Group A (p=0.03) after 20 months). The mfERG responses recorded preoperatively were subnormal in each case. Response densities of b–waves decreased in Group A and Group B at 3, 6 and 10 months postoperatively. After 20 months a statistically significant increase of response densities were measured in both groups (p=0.02). Comparing the response densities in Group A and Group B after 20 months, significantly higher increase in group B than in group A (p=0,043) was found. Conclusions: 1.A significant improvement in function of the outer retina – measured by mfERG – was found between 10 and 20 months postoperatively. 2. The higher significance in VA and RD improvement in Group B suggests the possible toxicity of ICG dye.

Keywords: electroretinography: clinical • macular holes • vitreoretinal surgery