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The relation between visual acuity and the size of fixational eye movements in patients with diabetic and
Purpose:
To study fixational eye movements as a function of visual acuity (VA) in patients with diabetic maculopathy and in patients with non-diabetic macular disease.
Material:
Two groups of patients each with VA ranging between 0.05-0.77 were studied, i.e. 24 patients with diabetic maculopathy and 23 patients with non-diabetic macular lesions. Fixational eye movements were quantified from video recordings of the ocular fundus obtained with the Rodenstock scanning laser ophthalmoscope.
Results:
Within both groups of patients we found a similar significantly negative relation between the amplitude of fast saccadic eye movements and the VA. Patients with VA > 0.20 showed a normal directional pattern with larger amplitudes of the fast saccadic movements in the horizontal than in the vertical plane, whereas for patients with VA < or = 0.20 the amplitudes of the saccadic movements in the vertical plane had enlarged to equal the saccadic amplitude in the horizontal plane. Four patients with VA < or = 0.10 had the fixation centre located more than three degrees (approximately 500 microns at the retinal plane) from the centre of the foveal avascular zone, whereas the fixation centre of the remaining 43 patients was within one degree of the centre of this zone.
Conclusion:
Patients with VA < or = 0.20 may have retinal areas of fixation located more than 500 microns from the fovea. This fact should be taken into account when planning retinal photocoagulation in macular disease.