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Fixation stability and implication for multifocal electroretinography in patients with neovascular age-related macular degeneration after anti-VEGF treatment

Pedersen, K. B.; Sjølie, A. K.; Vestergaard, A. H.; Andréasson, Sten LU and Møller, F. (2016) In Graefe's Archive for Clinical and Experimental Ophthalmology 254(10). p.1897-1908
Abstract

Purpose: To quantify fixation stability in patients with neovascular age-related macular degeneration (nAMD) at baseline, 3 and 6 months after anti-vascular endothelial growth factor (anti-VEGF) treatment and furthermore asses the implications of an unsteady fixation for multifocal electroretinography (mfERG) measurements. Methods: Fifty eyes of 50 nAMD patients receiving intravitreal anti-VEGF treatment with either bevacizumab or ranibizumab and eight eyes of eight control subjects were included. Fixation stability measurements were performed with the Eye-Link eyetracking system and the retinal area in degrees2 (deg2) containing the 68 % most frequently used fixation points (RAF68) was calculated. MfERG P1... (More)

Purpose: To quantify fixation stability in patients with neovascular age-related macular degeneration (nAMD) at baseline, 3 and 6 months after anti-vascular endothelial growth factor (anti-VEGF) treatment and furthermore asses the implications of an unsteady fixation for multifocal electroretinography (mfERG) measurements. Methods: Fifty eyes of 50 nAMD patients receiving intravitreal anti-VEGF treatment with either bevacizumab or ranibizumab and eight eyes of eight control subjects were included. Fixation stability measurements were performed with the Eye-Link eyetracking system and the retinal area in degrees2 (deg2) containing the 68 % most frequently used fixation points (RAF68) was calculated. MfERG P1 amplitude and implicit time were analyzed in six concentric rings and as a summed response. Patients were examined at baseline, 3 and 6 months. Four different mfERG recordings were performed for the control subjects to mimic an involuntary unstable fixation: normal central fixation, 2.4°, 4.8°, and 7.1° fixation instability. Results: For control subjects, a fixation instability of 2.4° (corresponding to the central hexagon) did not reduce mfERG ring amplitudes significantly, whereas 4.8° and 7.1° fixation instability reduced the amplitudes significantly in rings 1 and 2 (p <0.001) as well as in the peripheral rings in the 7.1° instability condition (p <0.001). Fixation stability improved non-significantly for patients at 3 and 6 months. The size of the retinal area of fixation was at baseline, 3 and 6 months negatively correlated to visual acuity (VA) (rbaseline = −0.65, r3 months = −0.60, and r6 months = −0.66 respectively, p <0.001) and mfERG amplitudes of the three innermost rings (rbaseline = −0.29, p = 0.042, r3 months = −0.43, p = 0.003 and r6 months = −0.31, p = 0.042). The VA cutoff for a fixation area less than 5 deg2 (approximately the central hexagon) was 65, 77, and 68 ETDRS letters (corresponding a maximal Snellen equivalent of 0.31) at baseline, 3 and 6 months, respectively. Conclusions: MfERG amplitudes in recordings of nAMD patients are at substantial risk of being reduced due to poor fixation as a large number of patients may use a fixation area of more than 5 deg2. Fixation monitoring during recording as well as interpretation of results should be performed with care, especially in patients with poor visual acuity.

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organization
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type
Contribution to journal
publication status
published
subject
keywords
Age-related macular degeneration, Anti-VEGF, Electrophysiology, Fixation stability, Multifocal ERG, Retinal area of fixation (RAF68)
in
Graefe's Archive for Clinical and Experimental Ophthalmology
volume
254
issue
10
pages
12 pages
publisher
Springer
external identifiers
  • Scopus:84963743676
  • WOS:000387129400005
ISSN
0721-832X
DOI
10.1007/s00417-016-3323-0
language
English
LU publication?
yes
id
8a0fc10c-8f13-4dbf-ad5c-919b19cd1c11
date added to LUP
2016-06-17 16:12:11
date last changed
2017-01-02 12:19:39
@article{8a0fc10c-8f13-4dbf-ad5c-919b19cd1c11,
  abstract     = {<p>Purpose: To quantify fixation stability in patients with neovascular age-related macular degeneration (nAMD) at baseline, 3 and 6 months after anti-vascular endothelial growth factor (anti-VEGF) treatment and furthermore asses the implications of an unsteady fixation for multifocal electroretinography (mfERG) measurements. Methods: Fifty eyes of 50 nAMD patients receiving intravitreal anti-VEGF treatment with either bevacizumab or ranibizumab and eight eyes of eight control subjects were included. Fixation stability measurements were performed with the Eye-Link eyetracking system and the retinal area in degrees<sup>2</sup> (deg<sup>2</sup>) containing the 68 % most frequently used fixation points (RAF68) was calculated. MfERG P1 amplitude and implicit time were analyzed in six concentric rings and as a summed response. Patients were examined at baseline, 3 and 6 months. Four different mfERG recordings were performed for the control subjects to mimic an involuntary unstable fixation: normal central fixation, 2.4°, 4.8°, and 7.1° fixation instability. Results: For control subjects, a fixation instability of 2.4° (corresponding to the central hexagon) did not reduce mfERG ring amplitudes significantly, whereas 4.8° and 7.1° fixation instability reduced the amplitudes significantly in rings 1 and 2 (p &lt;0.001) as well as in the peripheral rings in the 7.1° instability condition (p &lt;0.001). Fixation stability improved non-significantly for patients at 3 and 6 months. The size of the retinal area of fixation was at baseline, 3 and 6 months negatively correlated to visual acuity (VA) (r<sub>baseline</sub> = −0.65, r<sub>3 months</sub> = −0.60, and r<sub>6 months</sub> = −0.66 respectively, p &lt;0.001) and mfERG amplitudes of the three innermost rings (r<sub>baseline</sub> = −0.29, p = 0.042, r<sub>3 months</sub> = −0.43, p = 0.003 and r<sub>6 months</sub> = −0.31, p = 0.042). The VA cutoff for a fixation area less than 5 deg<sup>2</sup> (approximately the central hexagon) was 65, 77, and 68 ETDRS letters (corresponding a maximal Snellen equivalent of 0.31) at baseline, 3 and 6 months, respectively. Conclusions: MfERG amplitudes in recordings of nAMD patients are at substantial risk of being reduced due to poor fixation as a large number of patients may use a fixation area of more than 5 deg<sup>2</sup>. Fixation monitoring during recording as well as interpretation of results should be performed with care, especially in patients with poor visual acuity.</p>},
  author       = {Pedersen, K. B. and Sjølie, A. K. and Vestergaard, A. H. and Andréasson, Sten and Møller, F.},
  issn         = {0721-832X},
  keyword      = {Age-related macular degeneration,Anti-VEGF,Electrophysiology,Fixation stability,Multifocal ERG,Retinal area of fixation (RAF68)},
  language     = {eng},
  number       = {10},
  pages        = {1897--1908},
  publisher    = {Springer},
  series       = {Graefe's Archive for Clinical and Experimental Ophthalmology},
  title        = {Fixation stability and implication for multifocal electroretinography in patients with neovascular age-related macular degeneration after anti-VEGF treatment},
  url          = {http://dx.doi.org/10.1007/s00417-016-3323-0},
  volume       = {254},
  year         = {2016},
}