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M.D. Bailey, L. Sinnott, D.O. Mutti; Oscillations of the Crystalline Lens Following Saccadic Eye Movements . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5854.
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To determine if tension on the crystalline lens can be assessed in vivo by measuring the amplitude and duration of oscillations of the crystalline lens following saccadic eye movements.
Ten subjects, ages 20 to 50, made abducting saccadic eye movements (20°) between two targets at distance (dilated and undilated at 3.4 meters) and during accommodation (25 cm, undilated). Purkinje images I and IV of the right eye were monitored with a video camera at a rate of 1000 frames/second throughout the saccade. The difference in horizontal position between Purkinje I and IV during and following the saccade yielded the amplitude and duration (half–period) of the oscillations of the crystalline lens following the saccade. The mean of the differences across measurement conditions was compared to zero using paired t–tests.
The difference in amplitude of the oscillations between undilated distance (mean = 1.69°) and accommodated (mean = 3.29°) conditions was significantly different from zero (mean difference ± SE = 1.6° ± 0.39, p = 0.002), as was the difference between undilated distance (mean = 1.69°) and dilated distance (mean = 2.04°) conditions (mean difference ± SE = 0.35° ± 0.15, p = 0.04). The difference in the half–period of the oscillations between undilated distance (mean = 14.9 msec) and accommodated (mean = 17.6 msec) conditions was also significantly different from zero (mean difference ± SE = 3.0 msec ± 1.0, p = 0.004).
The amplitude and duration of oscillations of the crystalline lens increased under accommodated conditions, indicating that the crystalline lens is held with reduced zonular tension during accommodation. It appears that the amplitude and duration of the oscillations of the crystalline lens following saccadic eye movements may be a useful measurement of the tension on the crystalline lens. This measurement could be used in research on theories of accommodation and to evaluate mechanical factors related to refractive error development.
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