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F. Moeller, M.L. Laursen, A.K. Sjolie; Binocular Fixation Topography in Patients With Diabetic Macular Oedema – Relation to Visual Acuity and Retinal Thickness . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1477.
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Purpose: During retinal photocoagulation for diabetic maculopathy there is a potentional risk of foveal burns and laser scars may increase over time to involve retinal areas within 1/3 of a disc diameter from the centre of the fovea. The increased laser scars may possibly be sight threatening when involving retinal areas previous used during fixation. Since the retinal area used during binocular steady fixation has been found to vary considerably in normal test person, and central fixation may be even further compromised in patients with diabetic maculopathy, the sight threatning side effects could possibly be reduced by taking into account the fixation area individually. However, no study has described and quantified the retinal area of fixation binocularly in patients with clinically significant macular oedema (CSME). Methods: Sixteen diabetic patients with CSME in one or both eyes were examined. Each examination included visual acuity testing (ETDRS chart), a standard eye examination, central retinal thickness assessment by Optical Coherent Tomography, fluorescein angiography and binocular quantification of fixational eye movements using an infrared recording technique. Results: A negative correlation was found between the visual acuity and the mean microsaccadic amplitude (r=0.48, p=0.009). The maximal retinal extension of the fixation area ranged between 1.0 and 3.0 degrees, and in 2 eyes with CSME this area was estimated to exceed 800 microns on the retinal plane. No correlation was found between the retinal thickness and the visual acuity, the retinal area of fixation, the maximal extension of the fixation area or the mean microsaccadic amplitude. Conclusions: Large interindividual differences in the quantitative measures of the binocular fixational eye movements were found among the patients. The mean amplitude of the fixational eye movements was not correlated to the central retinal thickness, and the fixation area could only partly be predicted by the visual acuity. Two eyes with CSME had an estimated maximal extension of the fixation area exceeding the central 800µm on the retinal plane, thus the possible benefit of individualising central photocoagulation according to precise measures of the fixation area needs to be investigated on a larger population.
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