Eye dryness, floaters common in hATTR-PN, but more research needed
Review study finds patients often experience ocular complications
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People with hereditary transthyretin amyloidosis with polyneuropathy (hATTR-PN) often experience eye-related complications such as eye dryness and floaters in the field of vision, according to a review study.
However, available scientific evidence does not allow researchers to determine exactly how common these eye manifestations are. The study’s researchers are therefore calling for greater efforts to explore exactly how and how often the eyes are impacted in hATTR-PN and related diseases.
The study, “Ophthalmological Manifestations of Hereditary Amyloidosis due to Transthyretin: A Systematic Review,” was published in the Journal of Ophthalmology.
Most studies in review showed medium, high risk of bias
Hereditary ATTR refers to a group of progressive diseases caused by mutations in the TTR gene that result in the buildup of toxic clumps of a faulty transthyretin protein in tissues, causing damage.
The disease typically appears in two main forms. In hATTR-PN, transthyretin toxic clumps accumulate mainly in the nerves outside the brain and spinal cord. In hereditary transthyretin amyloid cardiomyopathy (hATTR-CM), this accumulation occurs mainly in the heart. Increasing evidence shows that many people with hereditary ATTR may experience both nerve and heart problems (mixed profile).
Eye-related problems have been reported in people with hereditary ATTR, most commonly the hATTR-PN form, but it’s not clear what types are most common. Seeking to learn more, a team of scientists in Brazil conducted a review, combing through the available scientific literature to determine what’s currently known about eye involvement in hereditary ATTR.
The review included 16 studies covering 1,792 patients, with more than 90% carrying Val30Met, the most common hATTR-PN-causing mutation. Most studies involved people with hATTR-PN.
Most of the studies showed a medium or high risk of bias, indicating a likelihood that their results may be distorted by flaws in design, conduct, or reporting.
“Additionally, it is important to note that the studies included in this work varied significantly in design, population, and outcome assessment methods and [did] not always provide numerical data,” the researchers wrote. “Another point to consider is that most articles had small patient samples, limiting the ability to perform meaningful statistical associations or inferences.”
High amount of variability between studies
Most studies (87.5%) assessed the presence of vitreous opacities, also known as floaters, which are buildups in the eye that cause specks or threads to appear in the vision. On average, vitreous opacities were reported in just over a third of patients. However, the researchers noted that there was substantial variability in this rate across studies, suggesting that simply looking at the average may not be a reliable measure.
The presence of dry eye was assessed in half of the studies, with an average prevalence of 47.8%. Again, however, there was substantial variability across studies, making it hard to draw a reliable estimate of exactly how common this symptom is.
Other eye symptoms, such as abnormal pupils and glaucoma (damage to the nerve connecting the eyes to the brain), showed similar trends. Available studies made it clear that these symptoms affect many people with hereditary ATTR, but because there was so much variability between studies, it wasn’t possible to draw any reliable conclusions.
The researchers noted that bleeding at the back of the eye was documented in only a handful of studies, suggesting this complication is not common in this patient population.
Because the available data were highly variable and low-quality, the researchers also weren’t able to conduct reliable analyses to compare eye manifestations between hATTR-PN and hATTR-CM patients. Overall, the scientists said their review highlights the ongoing need for further study of how the eyes are affected in hereditary ATTR.
“There remains a continuous need for research in this field to address knowledge gaps and improve the quality of ophthalmic care provided to patients with [hereditary ATTR],” the team concluded.
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