Intravitreal use of bevacizumab (Avastin) for choroidal neovascularization due to ARMD: a preliminary multifocal-ERG and OCT study
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- Moschos, M.M., Brouzas, D., Apostolopoulos, M. et al. Doc Ophthalmol (2007) 114: 37. doi:10.1007/s10633-006-9036-7
To evaluate by MFERG and OCT the macular function before and after intravitreal use of bevacizumab (Avastin) in eyes suffering from CNV due to ARMD.
Eighteen eyes with subfoveal CNV due to ARMD were studied before and after intravitreal use of bevacizumab with MFERG and OCT. The post treatment follow up was three months.
Before treatment, OCT shows an increase of the retinal thickening of the fovea and the electrical response densities in the fovea and parafovea were decreased in all patients. Three months after treatment, OCT showed a real resolution of the subretinal fluid. The electrical responses in the fovea and parafovea remained the same or slightly improved in some cases. The intraocular pressure remained normal and no inflammation was observed.
The intravitreal use of bevacizumab may provide anatomical correlates that support the concept of disease amelioration but the functional improvement of the macula three months after treatment is not obvious. However the method is promising and needs further evaluation.
KeywordsAge related macular degeneration (ARMD)Bevacizumab (Avastin)Choroidal neovascularization (CNV)Multifocal Electroretinogram (MFERG)Optical Coherence Tomography (OCT)
Choroidal neovascularization (CNV) is a leading cause of loss of central vision in developed countries . The neovascularization originates from choroidal blood vessels and grows through Bruch’s, membrane usually at multiple sites into the sub-retinal pigmented epithelial space and disrupts the anatomy of retinal pigment epithelium photoreceptors complex [2–4]. While about 10–15% of cases of ARMD involve leaky revascularizations forming in the choroid behind macula, they account for roughly 90% of the cases of severe and relatively rapid visual loss attributable to ARMD.
The potentially poor natural history of many subfoveal CNV lesions and the limitations of thermal laser photocoagulation for these lesions have prompted the search for alternative treatment modalities, including photodynamic therapy [5–7]. More recently agents that block the effects of vascular endothelial growth factor (VEGF) have been used to treat CNV secondary to age macular degeneration. The role, efficacy and safety of anti-VEGF therapies for use in the treatment of age macular degeneration was first established by clinical trials of pegaptamid sodium (Macugen) and then later by clinical trials for ranibizumab (Lucentis). Patients treated with pegaptamid had a modest, but statistically significant, benefit as compared with patients not treated with pegaptamid . However, only 6% of patients had improvement of visual acuity after the first year of treatment with pegaptamid . In more recent studies Phase III clinical trials for ranibizumab demonstrated superior results at year one, showing that the majority of patients treated with ranibizumab had less vision loss than those treated with placebo. Bevacizumab binds all biologically active forms of VEGF, as ranibizumab does. It is currently approved for use in humans but is labeled for cancer treatment . In our study, we offered off-label intravitreal use of bevacizumab to patients with CNV due to ARMD not expected to respond to conventional methods of treatment. The criteria leading to intravitreal use of Avastin was extensive subretinal neovascularization more than 3.0 disc diameter and less than 50% classic component. Visual function before and after treatments is assessed by decimal Snellen optotype visual acuity (VA) measurement. However, the visual acuity represents a single parameter of the impaired visual function resulting from the CNV.
The purpose of this study is to record the electroretinographic changes of the foveal and perifoveal area by means of MFERG in eyes with subfoveal CNV concurrently with OCT changes before and after intravitreal use of bevacizumab and to assess objectively its efficacy. The MFERG, introduced by Sutter and Tran  allows the simultaneous derivation of 61 or 103 local ERGs signals in a central visual field of 30° diameter around the fovea. This technique allows the functional mapping of the retina and contributes to the detailed evaluation of the retinal function especially in regional disorders of the outer retinal layers.
Materials and methods
The present study includes 18 eyes of 18 consecutive patients with CNV secondary to ARMD treated with off-label intravitreal bevacizumab. All eyes had large occult or minimally classic lesions. In these cases no benefit would be expected by using any alternative method of treatment.
The study protocol was approved by the local institutional review board of our hospital and all the patients signed a written consent statement particularly in the regard to the off-label use of intravitreal use of bevacizumab.
Clinical data of patients with CNV due to ARMD before, 1 and 3 months after treatment
VAa before treatment
VAa 1 month after treatment
VAa 3 months after treatment
Also none of the patients had ocular diseases such as high myopia, central or diffuse retinal degeneration that might influence the MFERG recording.
All patients at presentation underwent a complete ophthalmic examination, including measurement of best-corrected visual acuity, fundus examination, intraocular pressure measurement, fluorescein angiography, OCT scan and MFERG recording.
Best corrected visual acuity was measured by means of standard Snellen chart and two masked evaluators were used to determine visual acuity at baseline, 1 and 3 months after treatment.
The procedure was carried out in the operation theatre. Topical proparacaine hydrochloride 0.5% was applied to the ocular surface followed by preparation with 5% povidone iodine. A cotton-tipped applicator soaked in proparacaine hydrochloride was then applied to the injection site 4 mm posterior to the limbus. The intravitreal dose of bevacizumab (Avastin) was 1.25 mg/0.05 ml. Bevacizumab was placed in a 0.5-ml syringe with an integrated 31-gauge needle and 0.05 ml was injected into the vitreous. Indirect ophthalmoscopy was used to confirm uneventful intravitreal placement of the suspension.
Visual acuity and MFERG monitored the functional response to treatment. The anatomical improvement was assessed by OCT central macular thickness measurement at 1 and 3 months after in injection.
Optical coherence tomography (OCT)
OCT examination was performed with the Humphrey model 3000. (Humphrey Instruments, Carl Zeiss, Inc, Dublin, California). The retinal mapping software was used calculating averaged retinal thickness of the central ring. All eyes were scanned in a radial spoke pattern centered on the foveola with scan length of 5 mm.
The subjects were asked to gaze at the fixation light within the machine and the foveolar fixation was confirmed by observing the retinal through the infrared monitoring camera. The retinal thickness was calculated as the distance between the two boundaries along each A-scan using the attached automatic boundary detection software. The software automatically detects the vitreoretinal junction as the inner retinal boundary and the chorioretinal junction as the outer boundary.
For the recording of the MFERG, the VERIS III (Visual Evoked Response Imaging System; Tomey, Nagoya, Japan) was used. The stimulus matrix consisted of 61 hexagonal elements displayed on a CRT color monitor driven at a frame of 75 Hz. These hexagons elicit approximately equal signal amplitude at all locations on a normal retina.
Each hexagon was independently alternated between black and white at a rate of 75 Hz, and the stimulation technique allowed a retinal response from each stimulus. The luminance of the stimulus for white was 200 cd/m2 and the contrast was 99.3%. The radius of the stimulus array subtended approximately 20° high and 25° wide. The bandwidth of the amplifier was 10–300 Hz (-6bd/oct), and the amplification was ×10,000.
The pupils of the patients were dilated by means of tropicamide 0.5% and phenylephrine 5% and the eyes were optically corrected for near vision to see clearly the small fixation spot in the center of the stimulus matrix. For signal acquisition a bipolar contact lens was used in which the active and the reference electrodes were incorporated in the contact lens. The ground electrode was attached to earlobe. The fellow eye was closed and the duration of the data acquisition was 4 min divided into eight sessions of 30 s. During test the room light was left on. The recording procedure was repeated if there were spurious potentials from eye blinks or if ocular movement were recorded.
The response density (amplitude per unit retinal area, nV/deg2) of each local response was estimated as the dot product between the normalized response template and each local response.
The MFERG stimuli location and anatomic areas corresponded roughly as follows: ring 1 to the fovea, ring 2 to the parafovea, ring 3 to the perifovea, ring 4 to the near periphery and ring 5 to the central part of the middle periphery. The amplitude of each group was scaled to reflect the angular size of the stimulus hexagon, which produces the response. These averages give a more accurate view of the relative response densities of each group. The average of retinal response density of the retinal area corresponding to ring 1 (fovea) is approximately 22.97 nV/deg2, to ring 2 (parafovea) is 12.17 nV/deg2, to ring 3 (perifovea) is 11.8 nV/deg2, to ring 4 (near periphery) is 10.0 nV/deg2 and to ring 5 is roughly 10.0 nV/deg2. The retinal response density decreases with eccentricity, although there is no further decrease from ring 4 to ring 5.
The paired two-tailed t-test was used to calculate the significance of the mean differences between baseline values and 1 and 3 months values. The Kolmogorov–Smirnov test was used to test the normality of distribution. If the data fail the normality test the non-parametric Wilcoxon matched-pairs signed-rank test was used. If the pairing was not effective the unpaired t-test with Welch correction was used.
At presentation visual acuity ranged from 0.05 to 0.9 and the mean visual acuity was 0.24 (SD 0.27). One month after treatment the visual acuity ranged from 0.05 to 0.9 and the mean visual acuity improved to 0.27 (SD 0.26) and the difference was statistically significant (P < 0.05). Three months after treatment best-corrected visual acuity ranged from 0.05 to 0.9 and the mean visual acuity was 0.25 (SD 0.267). No significant difference was found between VA at baseline and 3 months after treatment (P = 0.2261) (Table 1).
OCT and MFERG recordings of area 1 and 2 before, 1 and 3 months after treatment
1 month after treatment
3 months after treatment
1 month after treatment
3 months after treatment
Before treatment, the retinal response density of MFERG of central area (area 1) ranged from 0.92 to 14.25 nV/deg2 and the mean value was 4.09 nV/deg2 (SD 3.79). One month after injection the retinal response density ranged from 2.08 to 14.96 nV/deg2 and the mean value was 5.25 nV/deg2 (SD 3.77) and the difference is statistically significant (P < 0.05). Three months after treatment the retinal response density of MF-ERG ranged between 1.95 and 14.5 nV/deg2 and the mean value was 4.73 nV/deg2 (SD 3.35). No difference was found between baseline and 3 months (P = 0.1285) (Table 2).
It should be stressed that 3 months after treatment, the retinal response density of area 1 improved more than 1 nV/deg2 in eight cases (case no 4, 5, 9, 10, 13, 15 and 17), decreased in two cases (case no 8 and 12) and remained almost stable in the remaining eight cases. The retinal response density of area 2 recorded by MFERG improved of more than 1 nV/deg2 in four cases (case no 3, 5, 7 and 8) and remained almost unchanged in the remaining 14 cases.
Finally, at presentation the mean intraocular pressure (IOP) ranged from 12 to 18 mmHg to the mean value was 15.44 mmHg (SD 1.69). One month after treatment the IOP ranged from 14 to 18 mmHg, mean value 15.77 mmHg (SD 1.55) and 3 months after treatment, the IOP ranged from 14 to 18 mmHg, mean value 15.72 mmHg, (SD 1.56). No statistically significant difference was found between baseline and 1 and 3 months after treatment (P = 0.4688 and 0.791, respectively).
The treatment of choroidal revascularization in ARMD has changed enormously during the last decade. While 10 years ago there was only argon laser coagulation, today we have several treatment options for different types of CNV . Recent studies have suggested that VEGF may be an important stimulus for neovascular age-related macular degeneration. Bevacizumab is a recombinant humanized, full length, anti-VEGF monoclonal antibody that binds all isoforms of VEGF-A. Latest studies show that the intravitreal use of bevacizumab may offer in the treatment of the CNV due to age macular degeneration [12–14].
In this retrospective study 18 eyes with CNV due to ARMD were treated with intravitreal bevacizumab. Our results show that there are anatomical correlates to support the concept of disease improvement. 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. Also the MFERG improvement did not follow the decrease of macular thickness and is significant the first month after treatment (P < 0.05).
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 the vision. Three months after treatment all studied parameters seem to return to pretreatment level. However MFERG results, 3 months after treatment, show a little rise of the electrical activity of area 2 (P < 0.05), which may be attributed to the decrease of the macular edema more than to the improvement of the macular function [15, 16].
It is important to stress that no patient manifested ocular or systemic side effects or IOP increase.
The short-term results of this study showed an important decrease of macular thickening the first month after intravitreal injection of bevacizumab, a smaller increase of visual acuity and an improvement of electrophysiological responses of macular area. However the anatomical improvement is very promising and further investigation should be performed.