Prism glasses allow people with muscular eye degeneration to look upwards or downwards more easily.
Glass prism with cut glass handles, probably England, 19th century. On display in Enquire, Level 5, National Museum Of Scotland
Nerve damage surrounding the eyes can make it difficult or painful for a person to control their eye movement, preventing them from looking wherever they please. Patients with Progressive Supranuclear Palsy (PSP) or other eye muscle degeneration often experience this problem of a fixed gaze, with the inability to look up or down. Being unable to look up or down can make it difficult to read a book, eat a meal, or even look at the person you are having a conversation with. Everyday tasks become much more complicated when you can’t control where you look.
In an effort to treat the fixed gaze symptom caused by Progressive Supranuclear Palsy, optical clinician and expert, Dr. Anne Silk, created prism glasses, changing the way PSP patients experience and see the world.
“Look right down and fix your gaze on the floor. Now imagine that you want to have a conversation with a friend opposite you but you can’t look up – you can see their feet but not their face. The same might happen when you want to watch TV. Now consider the opposite effect: your gaze is fixed looking up so you can’t read or see your meal on the table but you can only gaze at the ceiling.- Dr. Anne Silk, 2016
Prism glasses, as their name suggests, are glasses with prisms in their lenses. Through the use of multiple reflective surfaces, images can be rotated through 90 degrees. This fairly simple mechanism shifts previously unseen images into the wearer’s line of sight.
These glasses have helped tremendously to treat the symptoms of PSP. Although not useful while walking, prism glasses have made eating, in particular, much easier for PSP patients, as wearers can now easily find the food on their plates.
People suffering from PSP can request a free pair of prism glasses from PSP Association.