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Victor M Hernandez, Marco Ruggeri, Fabrice Manns, Jean-Marie A Parel; Measurement of Accommodation with High Dynamic Range Using a Shack-Hartmann Wavefront Sensor and Dual Channel Accommodation Stimulus. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6010.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a combined Shack-Hartmann wavefront sensor and modified extended range dual-channel Badal optometer stimulus for the dynamic refractive measurement of accommodation with high dynamic range without refractive correction, and with a long working distance to allow coupling with an Optical Coherence Tomography system for simultaneous lens biometry.
We designed a system that combines a superluminescent diode emitting at 750 nm and a Shack-Hartmann wavefront sensor (WFS150-5C, Thorlabs; Newton, NJ) equipped with a 4-f relay system via a hot mirror to a two channel (far/near) accommodation stimulus (Figure 1). The 4f relay system uses f=100 mm lenses to provide a working distance sufficient to allow future combination with an anterior segment OCT system. The accommodation stimulus was designed to present a 10 D stimulus in subjects with refractive error ranging from -10 D to +6 D. The far target channel is used as a baseline and adjusted to provide a stimulus at the far point of the subject. The near target channel is adjusted manually to provide the desired amount of accommodation stimulus. The stimulus is presented via a microprocessor-controlled 1.8” liquid crystal display. Switching the displays on/off provides a step-stimulus that allows measurement of the dynamic accommodative response. The system was mounted on an adjustable motorized slit-lamp table. Preliminary experiments were performed on 4 subjects (age range: 24-49, refractive error range: -8 D-+1.75 D) following an IRB-approved protocol. The accommodative response to a stimulus ranging from 0 D to -6 D in 2 D was measured for the right eye of each subject.
The system was able to measure the accommodative response in all subjects when the stimulus was switched from far to near.
The preliminary experiments demonstrate the feasibility of the design.
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