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 coloured lenses (PCLs).
Members of the Ophthalmic Research Group conducted several studies into visual stress and stroke at Aston University in the UK. Case studies and controlled research investigated, and report 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 finding.
A research team in 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  that describes visual stress symptoms resulting from 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 of text may seem overwhelming. The cause of these difficulties may be visual stress; where lines of text (a pattern) trigger misperception and reading becomes difficult and even painful. The second controlled study  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 50% reduction in mistakes. The study concluded that 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 increase significantly over time.
 Beasley IG, Davies LN. Visual stress symptoms secondary to stroke alleviated with spectral filters and precision tinted ophthalmic lenses: a case report. Clinical and Experimental Optometry 2013 Jan;96(1):117-20.