Is multifocal ERG a reliable index of macular function after triamcinolone acetonide injection in diffuse diabetic...

To investigate the changes and the reliability of multifocal electroretinogram (mfERG) after intravitreal triamcinolone acetonide (IVTA) injection in diffuse diabetic macular edema (DDME).

Twenty-four eyes with DDME were treated with an intravitreal injection of 4 mg of triamcinolone acetonide. Visual acuity (VA), central macular thickness (CMT), mfERG, and intraocular pressures (IOP) were evaluated in the preinjection period and the 15th day, third month, and sixth month after IVTA injection.

Age and gender of the patients were not significantly correlated to logMAR VA (p=0.888 for age, p=0.192 for gender), CMT (p=0.282 for age, p=0.625 for gender), or P1/N1 amplitudes/implicit times in mfERG at baseline (p>0.05 for age and gender). The correlation between logMAR VA and CMT at baseline also was not significant (r=0.069, p=0.750). The VA increased significantly at the 15th day (p<0.001). The VA increase persisted until the third month and decreased to preinjection values at the sixth month (p=0.324). CMT decrease was significant at the 15th day (p=0.012) but insignificant at the third and sixth months (p=1.000 for both). Correlations between logMAR VA change/CMT change at the 15th day were not significant (r=-0.043, p=0.843). Moreover, the correlation of CMT change with P1/N1 amplitude/implicit time changes was not significant (p>0.05 for all).

The positive effect of IVTA injection in DDME is reversible until the sixth month. Monitoring of the improvement in visual function by mfERG is violated possibly by irreversible macular dysfunction due to long duration of macular edema and primary neurophysiologic effects of diabetes on the retina.