Studying the crowding effect in nystagmus 

People with infantile nystagmus syndrome are unable to control their eye movements. This near-constant movement of the visual world makes their vision blurry and impairs everyday tasks like reading and finding people in crowds.

Moorfields is seeing an increasing number of children and adults with nystagmus who seek further information, treatment and support due to the significant effect of nystagmus on their lives. 

We’re supporting Dr John Greenwood, UCL Experimental Psychologist, and Dr Vijay Tailor, an orthoptist at Moorfields Eye Hospital, to advance research into nystagmus and understand how the crowding effect impacts patients’ lives.

Infantile nystagmus syndrome is a visual disorder characterised by rhythmic and involuntary eye movements that develop around birth and persist throughout adulthood. 

Several factors, including albinism, can cause this condition or in cases of ​‘idiopathic’ nystagmus there is no apparent cause.

The most widely characterised visual deficit in nystagmus is reduced visual acuity - the ability to focus on objects or fine detail.

Vision in nystagmus is further disrupted by elevations in ​‘crowding’, an effect where objects, like letters, that are usually clear and visible on their own become challenging to recognise when surrounded by other objects.

We funded a PhD project for Dr Vijay Tailor, under the supervision of Dr John Greenwood, to study the crowding effect in adults with nystagmus due to albinism and in idiopathic nystagmus. 

People with albinism lack the pigment melanin, which affects the development of the light-sensing retina at the back of the eye and their eyesight. 

This study aimed to determine if eye movements cause the elevated crowding in nystagmus on a moment-by-moment basis (e.g., because objects become blurred together) or due to the inability of the brain to separate individual images (sensory deficit).

These findings pave the way for a better understanding of nystagmus and potential improvements in treatment strategies.

The crowding effect in nystagmus has been studied exclusively in adults, while childhood nystagmus remains an under-researched area. 

As well as affecting the quality of life, the constant eye movements have a pronounced effect on visual function.

It is essential to understand how these affect vision in children.

We continue to support Drs. Greenwood and Tailor to study the visual experience of children with nystagmus. This new study aims to measure the extent of the crowding effect in children with nystagmus and how this compares to children without nystagmus. 

Their findings could provide insight into the development of visual deficits associated with crowding in both albinism and idiopathic nystagmus in children and any changes in the brain’s visual areas that can occur in these conditions.

Suppose this research shows that the elevation of the crowding effect in children is severe. In that case, it could provide evidence to include crowding screening during diagnosis and clinical management. People experiencing this could start receiving specific guidance on coping with the crowding effect.

This could ultimately improve the screening for nystagmus and therapeutic approaches.

This project is funded from money for nystagmus research raised through Nystagmus Network supporters’ hard work and dedication.

Dr Vijay Tailor is a clinical vision scientist and research orthoptist and has completed his PhD. Vijay has extensive nystagmus expertise and works with patients in the nystagmus clinic at Moorfields Eye Hospital. 

Dr John Greenwood is an Associate Professor at the UCL Department of Psychology and has extensive experience with visual psychophysics in both healthy and clinical populations, as well as methods of eye tracking and testing vision in children.