Achromatopsia Might not be as Progressive as Previously Thought
By Andi M Skilton, on 8 September 2014
A recent publication from the UCL Institute of Ophthalmology, Moorfields Eye Hospital, and the Medical College of Wisconsin indicates that for the majority of people with achromatopsia, the condition may not be as progressive as previously suggested.
Data from this study by Aboshiha et al. demonstrated that for the majority of people with achromatopsia (a rare, inherited genetic disease of the eye) vision and the structure of the retina (the light-sensitive layer at the back of the eye) doesn’t worsen over time, and in the small number of people where it does, these changes in vision are slow and unrelated to a person’s age or to the genetic cause of their condition.
Published in the journal of Investigative Ophthalmology and Visual Science, this UK and US collaboration is the largest and longest follow up of patients with achromatopsia published to date with 38 people (20 men and 18 women, aged between 6 and 52) with genetically confirmed achromatopsia assessed for progression over an average of approximately two years.
Until fairly recently achromatopsia was described as being stationary i.e. that it did not change over time. However, a number of recently published studies using new retinal imaging techniques have suggested a possible worsening of achromatopsia as people age. Nearly all previous studies have been small cross-sectional studies (i.e. a range of different people were monitored and data collected at a set point in time) where as this study is longitudinal (i.e. we have monitored a range of different people but collected data over a period of time), which has helped to clarify the role of progression in achromatopsia.
Prof Michel Michaelides, Professor of Ophthalmology at the UCL Institute of Ophthalmology and Consultant Ophthalmologist at Moorfields, lead the study –
“In conditions where there is progressive worsening as people get older we often need to treat as early as possible to see a benefit. Currently there are no treatments for achromatopsia but due to promising results reported for gene therapy studies in animals, there are plans for human clinical trials in the near future. The data from this study indicates that because progression of achromatopsia is indeed quite minimal more people may be able to benefit from treatments in the future then we previously thought.”
- You can read the full paper on the IOVS website at: http://www.iovs.org/content/early/2014/08/06/iovs.14-14937.long
Achromatopsia causes the dysfunction of the light sensitive cone cells in the eye in approximately 1 in 30,000 people and is characterised by involuntary and repetitive movement of the eyes (nystagmus), poor clarity of vision (visual acuity) and sensitivity to light (photophobia). People with achromatopsia have mutations in one of five genes important for vision: CNGA3 and CNGB3, which account for 70% of all cases, as well as GNAT2, PDE6C and PED6H.
In 2013 the UCL Institute of Ophthalmology received a £2.1 million grant from the Medical Research Council to conduct an early phase I/II gene therapy clinical trial over the next five years in people with achromatopsia caused by defects in the CNGB3 gene. The clinical trial will assess if adding normal CNGB3 into the cells of the eye is safe and has any potential benefit for vision.