New eye exam shows promise of vision testing in children with CLN2

A new eye exam has been found useful for testing vision in children with CLN2 disease – also known as infantile late batten disease – who participated in a pilot study, its developer, Objective acuity (OAL), ad.

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

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

Its 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 ARVO 2021 Annual Meeting.

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

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Visual acuity readings of 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 when seeing a moving object or pattern. As such, it does not require any input from the tested child.

OAL technology uses a camera to track eye movements as the child watches a screen displaying a special pattern that researchers have called a “drift stimulant.” Camera data is analyzed using OAL proprietary algorithms to detect OKN. OKN’s presence 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 non-invasive technique called SD-OCT, short for optical coherence tomography in the spectral domain. SD-OCT allows researchers to take detailed photos inside the eye.

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

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

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

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

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

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


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