Long-term therapy stabilizes eye health in Fabry disease, study finds
Patients maintained stable vision, eye structures over median of 6.5 years
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A long-term study found that adults and children with Fabry disease receiving enzyme replacement or chaperone therapy generally maintain stable vision and eye structures over a median of 6.5 years.
While the nerve fiber layer in the retina — the light-sensitive tissue at the back of the eye — showed slight thinning over time, measurements remained within normal ranges.
The study, “Longitudinal assessment of the retinal phenotype in patients with Fabry disease undergoing continuous enzyme replacement and/or chaperone therapy,” was published in the Orphanet Journal of Rare Diseases.
Patients received ERT, chaperone therapy, or both
In Fabry, a lack of the enzyme alpha-galactosidase A (alpha-Gal A) causes fatty substances to build up inside cells and accumulate to toxic levels within tissues. This can gradually damage different organs, including the eyes. While available treatment options can help slow progression of the disease, their benefits for eye-related symptoms remain unclear.
In this study, researchers focused on two types of treatment: enzyme replacement therapy (ERT), which provides a functional version of alpha-Gal A, and chaperone therapy, which uses small molecules to help alpha-Gal A fold correctly and become functional.
The researchers reviewed medical records from 28 adults and children whose eyes were examined at the beginning of the study. However, only 21 patients, representing 42 eyes, were included in the final analysis. Seven patients were excluded because four stopped attending follow-up visits and three discontinued treatment.
Patients had a median age of 48 years. Most (71%) had classic Fabry disease, which typically manifests in childhood or adolescence, while the remaining (29%) had late-onset Fabry disease, which often develops later. All patients included in the final analysis continued receiving ERT, chaperone therapy, or a combination of both for a median of 6.5 years.
Median visual acuity was 20/20 at first and final examinations
Eye examinations measured several features, including best-corrected visual acuity, or how clearly a patient can see with the best possible vision correction; eye pressure; and the health of the front and back of the eye. The researchers also used optical coherence tomography (OCT) to produce detailed pictures of the retina.
The median visual acuity was 20/20 at both the first and final examinations, indicating normal vision. The researchers also examined hyperreflective foci, which are small, bright spots visible on OCT images. These spots may reflect changes in retinal tissue. The number and severity of these spots remained largely unchanged.
Another feature examined was retinal vessel tortuosity, which describes how twisted or curved the blood vessels in the retina appear. These blood vessels often look more twisted in Fabry disease. However, their appearance remained stable throughout the study, although male patients generally had more pronounced changes than female patients.
In conclusion, retinal manifestations in [Fabry disease] remained largely stable. Neither significant progression nor reversal of retinal alterations was observed over time.
Central retinal thickness, which indicates the thickness of the retina at its center, remained stable and within the normal range. Retinal nerve fiber layer thickness, which reflects the thickness of nerve fibers that carry visual information to the brain, decreased significantly by an average of 2.9 micrometers in males and 2.8 micrometers in females. However, measurements remained within the normal range.
The researchers also measured lyso-Gb3, a fatty substance that builds up in Fabry disease. Higher levels of lyso-Gb3 were associated with more hyperreflective foci and more twisted retinal blood vessels. However, lyso-Gb3 did not change significantly during follow-up.
“In conclusion, retinal manifestations in [Fabry disease] remained largely stable,” the researchers wrote. “Neither significant progression nor reversal of retinal alterations was observed over time,” they added.
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