Variety of Vision Problems Common With Angelman Syndrome

Eye issues from astigmatism to jerky movements can hamper development

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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A “wide spectrum” of vision impairments can be common in people with Angelman syndrome but may not be fully recognized, causing further difficulties in their cognitive and functional development, a study reported.

Based on the findings, researchers recommend that children diagnosed with Angelman undergo routine vision assessments so that early interventions can be given, if needed.

The study, “Neurovisual profile in children affected by Angelman syndrome,” was published in the journal Brain & Development.

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 Several eye issues most evident in Angelman patients with microdeletions

Eye-related abnormalities are common in people with Angelman syndrome. For example, many individuals exhibit strabismus, where the eyes do not line up with each other. However, studies exploring vision-related outcomes for people with Angelman are lacking.

“Data regarding basic visual functions in [Angelman] such as visual acuity are extremely limited and inconsistent due to the clinical profile of these patients that make assessment very challenging,” the researchers wrote.

“A comprehensive understanding of neurovisual profile in [Angelman] is needed to provide better clinical care since vision plays a central role in child development,” the team added, noting that “visual impairment may further interfere with adaptive, cognitive, and behavioral skills.”

To learn more, a team led by scientists in Italy conducted detailed eye assessments on 37 people with Angelman.

The patients ranged in age from just under 2 to nearly 21 years, and 23 were female. Most (70%) had a specific type of Angelman-causing mutation called a chromosomal microdeletion. All of the patients’ parents reported delays in motor development during early childhood, a common manifestation of Angelman.

Eye-related abnormalities were detected in all 37 patients. The most common were refractive problems like astigmatism — an imperfection in the curvature of the eye that interferes with how the eyes take in light and leads to blurred vision, and that can be corrected with interventions like prescription glasses. These problems were detected in all but one of the patients.

“The high prevalence of these easily correctable refractive errors in patients affected by [Angelman] underlines the importance of early screening to limit their negative sequelae on daily life activities, cognitive development and reading skills,” the researchers wrote.

Most of the patients (84%)  had abnormalities related to eye movement, such as unusually jerky movements. Nearly two-thirds (62%) had strabismus, and over half (57%) had fundus hypopigmentation (a reduction in coloration at the back of the eyes, where the light-sensing cells are housed).

In 25 patients ages 6 and older who could undergo visual acuity assessments, one had normal vision, 12 had near-normal vision, and another 12 had low vision, while none had very low vision. Contrast sensitivity — the ability to differentiate an object from the background — was reduced in 35% of the patients.

“Most of our study participants showed decreased visual acuity, while contrast sensitivity was compromised in about one third of the cases,” the researchers wrote.

They noted that reduced visual acuity may occur due to problems like refractive errors or fundus hypopigmentation. Abnormalities in how the brain processes visual data also likely contribute, according to the scientists.

“Considering this wide spectrum of visual impairments, we recommend a neurovisual evaluation at the time of diagnosis and annually,” the researchers concluded, noting that early intervention to manage visual problems “can improve children’s visual, neuromotor and cognitive outcomes.”

Statistical analyses showed that reduced contrast sensitivity, fundus hypopigmentation, and problems smoothly moving the eyes to follow objects were more common among patients with microdeletions than those with other type of mutations. These findings support the idea that patients with a microdeletion tend to develop more extensive eye-related abnormalities, the scientists said.

The team noted that this study is limited by its small sample size and the use of qualitative measures of eye function.