Polarization Perception in Health and Disease. Testing a New Sight Test: The TaNSiT Study

The recently described high sensitivity of the human eye to differentiate small angular differences in linear polarization and evidence supporting its macular origin (Misson, Anderson; 2017) suggests that human polarization sensitivity might be a useful diagnostic tool for macular disease. This augments a previous study in which we demonstrated the ability of the human visual system to detect isochromatic isoluminant polarization modulated pattern stimuli (Misson et al 2015).

This is an exploratory 'proof-of-concept' study to determine the clinical value of polarization pattern perception, PPP, in health and disease. We further propose that PPP might be valuable for the diagnosis, monitoring and early detection of macular disease. The latter includes common blinding conditions such as age related macular degeneration and diabetic retinopathy. It is also intended to investigate the effect of cataracts and cataract surgery on PPP: cataract surgery modifies the optics of the eye so might also modify PPP.

PPP is measured using a modification of the methodology described in (Misson et al 2015) and (Misson, Anderson; 2017) whereby polarization modulated patterns are presented on a modified LCD display. The observer's task is to report if they see an image and to describe the image. Images comprise simple patterns or traditional optotypes. A standard set of images are presented in pseudorandom order and the response recorded. A total score, the polarization pattern perception score PPP is then determined from the number of images seen/identified. A more refined metric, the polarization visual acuity pVA, will be derived from the response to the optotype stimuli. These data are then compared to conventional tests of visual structure and function including logMAR visual acuity, ocular examination and OCT scan data.

The study in anticipated to comprise:

Phase 1. Normative Evaluation: observational prospective cross-sectional.. A preliminary normative study will be undertaken on staff members. The aim is to quantify normative values in preparation for the clinical studies.