Author: Michael Carlson (United States)
Co-authors: Santosh Mahapatra, Sai Chavala, Subrata Batabyal, Gayatri Kanungo, Sanghoon Kim, Samarendra Mohanty
Purpose
Severe to near-total loss of vision in patients occurs due to a variety of ocular diseases including inherited retinal degenerations, age-related macular degeneration, and glaucoma. In the case of low vision patients, measurement of functional vision is challenging and requires multiparametric test methods to distinguish between patient sub-groups. Though there exists a number of devices to measure visual function in low-vision subjects, individually, these methods provide a measure of a single parameter. Further, it is unclear if these existing tests measure a clinically meaningful outcome, and therefore, are not widely accepted as a primary efficacy endpoint for low-vision studies. Low Vision Multi-Parameter Test (LVMPT) was developed to quantitively measure the visual level of low vision patients in clinical use and evaluate the progression of vision recovery after treatment
Setting/Venue
The LVMPT device was deployed in a clinical study to evaluate functional vision and therapeutic outcome of patients with Advanced Retinal Degeneration having poor vision (no better than PL and HM). The study was conducted after approval from the Drug Controller General of India (DCGI) registered Institutional Ethical Committee of a tertiary eye care center in eastern India.
Methods
The LVMPT device consists of two modalities: Two-dimensional (2D) LCD display to emulate real-world interaction with tablets and cell phones, and three-dimensional (3D) objects to emulate everyday interaction with objects. 2D display creates optical flow at different speeds and directions which tests the ability of subjects to recognize optical flow. Different shapes and sizes of objects are displayed on the 2D screen for the evaluation of low vision subjects. The 3D LVMPT device consists of a 3D enclosure with a top-lit LED panel, 3 possible object placement and is equipped with a slot containing sensors for object recognition. Subjects are evaluated based on correctly demonstrating the ability to recognize and pick up the directed object. The randomization of objects, light level control, recording of exact location and accuracy of the subject’s tap are automated by software.
Results
The LVMPT device was deployed in a clinical study with advanced retinal degenerated subjects. The functional vision evaluated by the LVMPT device was well correlated to the patient-reported outcome (evaluated by NEI VFQ-25 Questionnaire). The LVMPT-measured accuracy in shape recognition and/or threshold intensity, size, and speed of optical flow was found to correlate with visual acuity and functional vision measured by behavioral performance (light guided navigation test) of low-vision subjects. LVMPT device was able to discern between various subgroups of low vision patients.
Conlusions
The LVMPT device allows ophthalmologists to quantitatively measure low vision function and has wide use for quantifying degradation of vision and evaluation of drugs and therapeutic interventions. Further validation of the LVMPT in low-vision subjects will provide a correlation of clinically meaningful outcomes with treatment in various clinical trials focused on the advanced retinal degenerated patient population.
Financial Disclosure
Nanocospe Instruments Inc-Employee and Equity(Michael Carlson, Sanghoon Kim, Samarendra Mohanty) Nanocospe Therapeutics Inc-Employee and Equity(Sai Chavala, Samarendra Mohanty, Subrata Batabyal)
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