Study Finds Good Vision in Fabry Patients Despite Eye Changes

Eye symptoms may be 'clue' to diagnose disease in children

Steve Bryson, PhD avatar

by Steve Bryson, PhD |

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The image of a human eye is captured in the lens of a giant telescope as a person looks at the stars.

Despite disease-related eye changes, visual acuity — the sharpness of a person’s vision, with 20/20 denoting perfect clarity of sight — was “good” in children and adults with Fabry disease, a study showed.

Eye involvement was not associated with disease severity in adults with Fabry, and overall vision-related quality of life also was reported as good.

Researchers noted that opacities or scarring in the eye lens or cornea, the transparent layer on the eye surface, may suggest Fabry disease in children.

“Early ophthalmological signs could be a clue to help early [Fabry] diagnosis,” the team wrote.

The study, “Visual outcome, ocular findings, and visual quality of life in patients with Fabry disease,” was published in the journal Ophthalmic Genetics.

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Understanding eye issues in Fabry

Fabry disease is marked by the toxic accumulation of fatty molecules, primarily globotriaosylceramide (Gb3 or Gl-3), inside cells, causing tissue damage. While the disease mainly affects the heart, kidneys, brain, and spinal cord, it also causes cloudy-looking eyes in patients.

An estimated 90% of people with Fabry have corneal opacities — brown, grey, or yellowish streaks that appear on the cornea. At first, they may appear cloudy over the cornea but become more streak-like with time. Blood vessels in the eyes also may look twisted and/or slightly enlarged.

Although corneal opacities do not seem to affect vision, they are considered important for early diagnosis and disease monitoring. As such, additional knowledge of eye abnormalities in Fabry patients may help with diagnosis and avoid treatment delays.

To that end, researchers at the Karolinska Institutet, in Sweden, conducted a detailed eye examination of 26 people with Fabry disease to investigate visual disease, outcomes, and vision-related quality of life.

Participants included 16 males, ages 5–57, and 10 females, ages 30–63 years.

Enzyme replacement therapy was prescribed to 12 male and five female patients, and one male and one female were receiving Galafold (migalastat).

Higher (worse) FASTEX total severity scores to assess disease stability/progression significantly correlated with older age, but there were no differences between men and women.

Eight male and six of eight female patients (information was missing for two) reported poor vision, sensitivity to light, or dry eyes. Glasses were worn by 10 males and nine females, and five individuals had reduced visual acuity in one eye.

One male patient had amblyopia, also called lazy eye, while another had severe astigmatism, or imperfect eye curvature, which improved to full vision during follow-up. One woman had amblyopia and another cataract (cloudy eye lens). The team reported a lack of binocular vision, and difficulties with depth perception in four adults, and one had problems with eye movements.

Twisted and/or slightly enlarged blood vessels in the eye were observed in nine males and five females, and chemosis, a type of eye inflammation, occurred in two males. Cornea opacities were detected in 14 male and nine female patients, while lens opacities or cataracts occurred in 12 males and seven females.

Among the children, the most common abnormal finding was twisted blood vessels, present in four boys, followed by opacities in three, and cataracts in three.

Corneal topography, which measures the shape of the corneal surface, and tomography, a three-dimensional section of the cornea, was conducted on 12 participants (five women, five men, and two boys).

WTR or “with the rule” astigmatism — when the corneal curvature is steepest in the vertical direction — occurred in seven patients (two boys, three men, and two women). Meanwhile, oblique astigmatism, like a crossing pattern, was found in two men. In the women, astigmatism was mixed in different eyes, including WTR and oblique, as well as ATR or “against the rule” astigmatism, when curvature is steepest in the horizontal direction.

One of the women also was diagnosed with early-stage Fuchs dystrophy, in which fluid builds up in the cornea, causing swelling and thickening. Optical coherence tomography (OCT), which measures the light-sensing retina at the back of the eyes, was abnormal in two women who also had small cysts.

Fundus photography of the inner eye surface found evidence of either mild or moderate twisted blood vessels in 14 males and six of nine females. No sex-specific differences were seen.

Eight men and seven women completed the visual function questionnaire 25 (VFQ25) to evaluate vision- and health-related quality of life, with scores ranging from 0 (worst) to 100 (best). Overall, the VQF25 score was 93.6, with women scoring 90.6 and men 94.5. For distance activity subscore, women reported 83.3 and men 95.8.

Statistical analysis found a significant relationship between lower VQF25 scores for general health and worse FASTEX total severity scores.

“A majority of patients with [Fabry disease] had ocular changes,” the researchers concluded. “Despite ocular changes, [visual acuity] was usually good.”