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Juan Carlos Ondategui Parra, Jaume Pujol, Rosa Borras Garcia, Alfonso Sánchez-Magan, Juan Marcos Muñoz; New system based on HMD to objectively and automatically assess visual function and to perform visual therapy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):755.
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© ARVO (1962-2015); The Authors (2016-present)
Up to day, diagnosis of visual function disabilities in a clinical optometric examination is carried out through a battery of tests. Multiple parameters are evaluated sequentially, mainly subjectively and mostly with 2D stimuli. This is time-consuming, leads to patient fatigue and may be clinically misleading. Vision therapy is worse as the patient is prone to fatigue and the therapist works on subjective patient responses. A new Head Mounted Display (HMD) fully autonomous system is allowing for precise, objective and fast measurement of most visual function clinical parameters while the patient plays a true-3D (stimulating vergence and accommodation) short video game (<5min).
The system generates 3D images on two displays (one for each eye) where the different optotypes are presented, allows for measuring and correcting the patient’s refractive state, stimulates and relaxes patient’s vergence movements (through image disparity), as well as eyes accommodation (through variable focal distance), and records eyes and pupils movements. The system shows an interactive and engaging video game keeping patient interest on the stimuli while recording information. Preliminary system validation has been performed on a prototype. Key optometric parameters as Visual Acuity (VA) and phoria angle of deviation (Ph) have been measured and compared with conventional subjective measurements in a group of 15 healthy subjects with no previous history of strabismus or amblyopia. VA has been assessed in two different conditions: central static VA (csVA) with isolated optotypes and central dynamic VA (cdVA). The Ph was measured when cover and uncover test were performed.
csVA and cdVA results show <0.05 logMAR difference compared with standard clinical measure. cdVA presents an inversely proportional increase ratio of the VA and stimulus presentation speed. Ph results show a difference lower than 1,2 prismatic diopters and a clear dependence on the time of occlusion. All data have a correlation factor between 0.765 and 0,932.
The developed system is a powerful tool for objective assessment of the visual function. Preliminary validation data correlate well with conventional optometric results. Future work shall validate most visual function parameters and will exploit accurate data on patient responses to dynamic true-3D stimuli not at the reach of traditional methods.
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