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A new eye exam has been shown to be useful for testing vision in children with CLN2 disease – also known as late childhood Batten disease – who took part in a pilot study, its developer, Objective, has announced. Acuity (OAL).

Called the threshold visual acuity test, the test shows promise for use in children with CLN2 disease who are unable to cooperate with traditional vision tests, such as eye charts, due to losses in cognitive skills. , motor and linguistic.

The study was conducted in collaboration with Regenxbio, a biotechnology company developing gene therapies for a range of diseases, including CLN2 disease.

His conclusions,Pilot study of a new visual acuity test based on optokinetic nystagmus in children with CLN2 disease,were presented by Christina Ohnsman, MD, Senior Clinical Development Manager for Regenxbio, at the 2021 ARVO Annual Meeting.

The study included 23 children (aged 3 to 9 years) with CLN2 disease who were followed at the Hamburg-Eppendorf University Medical Center in Hamburg, Germany.

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Visual acuity readings for both eyes (binocular) and each eye separately (monocular) were obtained using the threshold visual acuity test.

This test is based on an involuntary reflex of the eyes, called optokinetic nystagmus (OKN), which occurs upon sight of a moving object or pattern. As such, it does not require any intervention from the child being tested.

OAL’s technology uses a camera to track eye movements as the child looks at a screen displaying a special pattern that the researchers called a “drift stimulus”. Camera data is analyzed using OAL’s proprietary algorithms to detect OKN. The presence of OKN indicates that the child can see the drifting stimulus, while its absence indicates the opposite.

Seventeen (74%) children had measurable binocular visual acuity, while six (26%) had no detectable OKN.

To assess the usefulness of the new test, the researchers sought to establish a relationship between visual acuity readings and measurements of central retinal thickness (CRT). According to the company, a progressive symmetrical loss of CRT has been well characterized in CLN2 disease.

CRT was measured under anesthesia using a noninvasive technique called SD-OCT, short for spectral domain optical coherence tomography. SD-OCT allows researchers to take detailed pictures inside the eye.

Binocular visual acuity was found to be strongly correlated with CRT. Monocular visual acuity readings were obtained in 12 right eyes and 11 left eyes, and were highly symmetrical between right and left eyes. They also correlated with CRT.

Binocular visual acuity readings were also obtained using preferential gaze – a vision test commonly used in young children unable to identify pictures or letters. However, these measures were poorly correlated with the CRT.

Based on these promising results, Regenxbio has signed an agreement to use OAL’s technology in future studies of RGX-381, an experimental gene therapy for CLN2 disease that is delivered directly into the retina to correct ocular CLN2 manifestations. .

“We are satisfied with the results of this study. Objective measurement of visual acuity obtained using OAL technology could allow Regenxbio to obtain additional data on the scope, severity and impact of visual impairment in patients with the disease CLN2 as we advance our gene therapy candidate to treat ocular manifestations of the disease,” Ohnsman said.

“It’s exciting to work with Regenxbio and see OAL’s technology potentially deployed in Regenxbio’s studies,” added Adam Podmore, CEO of OAL.

Regenxbio plans to provide updates on RGX-381 before the end of this year.