We’ve read several posts by parents saying they’ve been advised the optimum age for performing surgery to correct nystagmus is before age two (primarily on the American Nystagmus Network e-mail discussion list and Facebook page). As Jack is 18 months there is only a six month window of opportunity for him, so we’ve sought advice from experts to check we are doing the best we can for his eyesight.
I contacted Dr Dell’Osso to ask about the advantages of having surgery earlier rather than later and whether there is any research to prove the benefits. He said that he recently posted the following on a pediatric ophthalmology list about this subject.
“It is not known how much early intervention in INS (infantile nystagmus syndrome) improves final visual function. In cases with good foveation periods, even if not optimal, I don’t believe there would be a significant difference. My data for that is from the many, including myself, who had improved INS as a result of therapy late in life and whose acuity improved immediately to the same value that would be expected from their NAFX* values (i.e., there was no evidence of a sensory deficit). However, those INS patients with either associated afferent visual deficits and/or poor foveation periods, a case for early intervention could be made to avoid possible failure of the visual system to develop to its full potential. Without eye-movement data to determine foveation-period quality, early intervention may improve final visual function in the latter cases and would not diminish it in the former.”
*Note: The NAFX function uses uses eye movement measurements to predict the best possible visual acuity a person with nystagmus can achieve
He confirmed that there is not enough definitive research regarding the benefits of early therapy of INS as yet. However, early therapy can only help and will not hurt the development of the visual system. Only eye-movement recordings and NAFX analysis can determine which group a person is in in. Dr Hertle has equipment to check these at the Ackron Hospital, Ohio in the USA.
We’ve learned from a recent hospital visit that Professor Gotlobb’s team in Leicester, UK, also have the equipment. It’s currently being used on adults and they hope to start using it for children too in the future.
As it would be difficult for us to travel to the US to see Dr Hertle, we’ve asked Jack’s doctor if they think he falls into the “good foveation periods” category (to rule out the possibility his eyes may not develop to their full potential if he doesn’t have an operation before age two). We’ll write a follow up post when we know more. In the meantime, if you have any information or personal experiences relating to this we’d welcome hearing from you.