Pattern glare (sensitivity to patterns) and photophobia (light sensitivity) have known association with a range of conditions, including neurological conditions such as migraine, photosensitive epilepsy, autism, dyslexia, multiple sclerosis, and visual stress. Symptoms include difficulties with balance, depth perception, visual memory and cognitive deficits, double or blurred vision, and reading difficulties. Cortical hyperexcitability can occur following a stroke, and sensitivity to patterns and light are also often reported. These symptoms are reported by individuals with visual stress and are relieved with individually prescribed precision tinted lenses (PTLs).

 

Members of the Ophthalmic Research Group conducted several studies into Visual Stress and stroke at Aston University. Case studies and controlled research investigated and reported on the effects of precision tinted filter lenses on post-stroke symptoms. The papers are listed below and the following notes provide a recap of their statements and findings. 

 

A research team from the Aston University’s Ophthalmic Research Group recognized that stroke and Visual Stress report similar effects and symptoms including cortical hyperexcitability. Other symptoms reported for both include eyestrain, headaches, and light and pattern sensitivity, as well as illusions of colours, shapes and motion. They published a case study [1] that describes Visual Stress symptoms resulting from a stroke and their subsequent reduction with spectral filters and precision tinted ophthalmic lenses. The case also highlights that the spectral properties of the tint may need to be modified if the disease course alters. 

 

Stroke survivors often report reading difficulties. Words may appear to change or disappear, blur in and out and sentences or paragraphs may seem overwhelming. The cause of these difficulties may be Visual Stress; where lines of text (a pattern) trigger misperceptions and reading becomes difficult and even painful.

 

The second - controlled study [2] was undertaken to determine the effect of optimal spectral filters on reading performance following a stroke. This study reports that the use of the individually prescribed spectral filter led to an increased reading speed of 8% and a reduction of 50% in mistakes. The study concluded that spectral filters could immediately improve reading speed and accuracy following a stroke. While this study tested for prolonged use results, the benefits remained constant and did not significantly increase over time.