Lowering the cost of improved measurements of VA in real-world older patients

About This Grant

Project Summary Visual acuity (VA) is a key metric of retinal status in clinical trials and patient management, but measurements are often inaccurate due to the optical artifacts that are common in the aging eye. It is often unclear whether the retina, the optics, or both are the cause of reduced VA. The aging of the population has greatly increased visual impairment and blindness. The many treatment trials for age-related macular degeneration and diabetes make better VA measurements crucial. Critical barriers to accurate VA measurements remain with current wall charts or displays, whether computer screens or goggles. Pupil size is variable and usually decreased in older eyes, retinal illuminance is uncontrolled, and wavefront aberrations vary with pupil size and are uncontrolled. Wide field glare and crowding are problematic, especially for cataract patients with ghost images. Subjective refraction is typically prior to VA measurements. Traditional VA methods are problematic with an autorefractor, due to an unspecified or too large pupil and wavefront aberrations. The commonly used pinhole can reduce unwanted scattered light and defocus, but has decreased retinal illuminance and is sometimes difficult to position. Current VA methods lack quantification of variability. Two bottlenecks in patient flow are a) requiring subjective refraction instead of autorefraction b) measuring VA before pupil dilation. To address these, Aeon built a series of Potential Vision Tester (PVT) prototypes that project visual stimuli using Maxwellian view and a 3 mm pupil. Data to date indicate that PVT VAs are better than VAs from a wall chart or electronic display, when correcting sphere and cylinder. Correction of higher order aberrations thus far does not improve VA or SD. To demonstrate the feasibility of a more accurate VA test in the price range of electronic VA tests, in Aim 1 we will design, build, and optimize a new visual stimulation channel with tunable sphere and astigmatism correction. We will test 10 controls using the new tunable lenses, measuring wavefront aberrations for Zernike orders 1 – 6 for both the PVT and subject, then compare objective vs. subjective sphere settings and the resulting VAs. To reduce bottlenecks and inaccuracy in VA measurements due to anterior or posterior segment pathologies, in Aim 2 we will compare PVT VA vs. standard BCVA in selected groups (10 Ss/group). In Aim 2.1 we will compare VA measured with pupil dilation to > 5 mm vs. natural pupil using the PVT+pupil camera. In Aims 2.2 and 2.3, we will compare and model data for PVT VA vs. the BCVA with the DRCR/standard clinical protocol for patients with a) cataract, b) posterior capsule opacification post surgery, c) cylinder > 2.5D, d) coma > 0.4 microns for 3rd + 5th order Zernike polynomials, and probe combinations of measured higher order aberrations. An improved VA test device could lower barriers to new treatments and individual patient care, improve screening, or benefit AI models by leveraging robotic ophthalmic instruments with on board pupil alignment, as either a stand-alone or combination unit.