The area of fixation covaries with short-term changes in visual acuity after anti-vascular endothelial growth factor treatment in patients with diabetic macular oedema

Abstract

Purpose: Diabetic maculopathy can be treated with intravitreal injection of vascular endothelial growth factor (VEGF) inhibitors. However, the therapy is not effective in all patients, and it would be desirable to have parameters for differentiating patients who will benefit from treatment from those who will not. Retinal fixation has been shown to be impaired in patients with low visual acuity (VA) secondary to macular disease, but the changes in fixational eye movements after anti-VEGF treatment for diabetic maculopathy have not been investigated. Methods: Retinal fixation was studied in 29 patients with diabetic macular oedema before three monthly anti-VEGF injections, and 1 and 4 months after the last injection. The change in VA was correlated with changes in area, frequency, amplitude and total number of fixational saccades. Results: During three monthly injections, best-corrected visual acuity (BCVA) increased from (mean ± SD) 74.0 ± 11.5 Early Treatment Diabetic Retinopathy Study (ETDRS) letters to 78.3 ± 9.8 ETDRS letters, (p = 0.003) and central retinal thickness (CRT) decreased from (mean ± SD) 441.7 ± 107.0 μm to 339.5 ± 74.2 μm, (p = <0.0001), which was followed by the opposite changes after treatment (BCVA reduced nonsignificantly to 77.5 ± 10.4 ETDRS letters (p = 0.06), and CRT increased to 393.0 ± 9.8 μm, p = <0.0001). Both improvement and worsening of BCVA correlated with the fixation area (r2 = 0.28, p = 0.003 and r2 = 0.14, p = 0.045, respectively), but only improvement of BCVA correlated with the frequency (r2 = 0.15, p = 0.037) and total number of saccades (r2 = 0.18, p = 0.02). BCVA showed no correlation with the amplitude and most frequently occurring saccade amplitude. Conclusion: Fixational eye movements may be used to monitor short-term effects of anti-VEGF treatment on diabetic macular oedema. Future studies should aim at investigating a possible predictive value of fixational eye movements for visual function in the long term.