Dear Editor,

In the article entitled 'Electrophysiological effects of intravitreal Avastin (bevacizumab) in the treatment of exudative age-related macular degeneration (ARMD)' by Karanjia et al (Br J Ophthalmol 2008), the authors examine the sensitivity of multifocal-electroretinogram (mfERG) at measuring changes in retinal electrical activity in response to Avastin treatment for ARMD. In this interesting paper the authors study the changes of P1 response amplitude and support that this is the first study to demonstrate a statistically significant change in retinal electrical activity post-bevacizumab in patients with ARMD. I would like to draw attention to the authors of this article that in our prospective study 'Intravitreal use of bevacizumab (Avastin) for choroidal neovascularization due to ARMD: a preliminary mfERG and OCT study' by Moschos MM et al (Doc Ophthalmol 2007; 114:37-44) really for the first time we evaluated the macular function before and after intravitreal use of Avastin. In our paper based on the study of 18 eyes, 1 month after treatment the retinal response density of mfERG really shows an improvement but 3 months after treatment no difference was found between baseline and 3 months.

Our results show that there are anatomical correlates to support the concept of disease amelioration 1 month after treatment. This is mainly the decrease of macular thickness as measured by OCT in an extremely significant degree (p<0.001) the first month after treatment. On the contrary the mean visual acuity improved only by 0.03 the first month after treatment and by 0.02 three months after treatment. On the contrary the mfERG improvement did not follow the decrease of macular thickness and is significant only the first month after treatment. These findings show that the increase of visual acuity, as also the improvement of electrical responses of the macular area is disproportional to the decrease of macular thickness. This may be explained by the fact that macular edema is only a parameter that may affect visual acuity and electrophysiological responses in the beginning of the disease. Atrophy of the retina, particularly of the photoreceptors, atrophy of the pigment epithelium and scarring are all unmeasured variables, which influence vision [1, 2].

References

1. Moschos M, Brouzas D, Apostolopoulos M, et al. Intravitreal use of bevacizumab (Avastin) for choroidal neovascularization due to ARMD: a preliminary multifocal-ERG and OCT study. Doc Ophtalmol 2007;114:137-144.

2. Moschos M, Panayotidis D, Theodossiadis G, et al. Assessment of macular function by electroretinography in age-related macular degeneration before and after photodynamic therapy. J Fr Ophtalmologie 2004;27:1001-1006.

Marilita M Moschos, MD, PhD Department of Ophthalmology, University of Athens, Athens, Greece

Correspondence and reprints: Moschos M. Marilita MD, PhD 144, Kountouriotou Str 185 35 Piraeus Greece Tel : ++30 6944887319 Fax: ++30 210 4122139 E-mail: moschosmarilita@yahoo.fr