Collagen deficiency in Alport syndrome leads to retina dysfunction due to changes in the retina’s cellular structure, finds a new study, “En face optical coherence tomography findings in a case of Alport syndrome,” that appeared in the Indian Journal of Ophthalmology.
Alport is caused by a genetic mutation that attacks collagen structures in the basement membrane – a thin matrix layer that connects internal and external organ tissues. This condition is mainly characterized by kidney dysfunction that can progress to kidney failure. But patients commonly experience other symptoms such as hearing loss and vision problems.
These include dot-and-fleck retinopathy characterized by small, yellowish dots in the retina, alterations on the retina structures, anterior lenticonus (deformed eye lens), and corneal dystrophy caused by a buildup of material on the cornea.
All these symptoms are well-recognized as being related to Alport. However, scientists don’t fully understand the specific alterations that may affect each retinal layer in this illness.
In the study, a team led by In Hwan Cho of South Korea’s Soonchunhyang University Cheonan Hospital used a non-invasive technique called en face optical coherence tomography (OCT) to conduct a detailed analysis of all retina layers in a 24-year-old Alport patient.
The normal retina needs collagen fibers to form its internal limiting membrane (ILM) and retinal pigment epithelium (RPE). The ILM is the physical barrier that protects the retina from toxins or physical traction, and the RPE is the cellular layer that connects with the optical sensory cells. Altering these membranes can significantly damage the adjacent structures and change visual acuity.
With the use of en face OCT, the research team was able to detect different areas on the ILM and RPE retina layers that were reflecting too much or not enough light. This finding suggested that the primary effects of Alport collagen deficiency were on the ILM and RPE basement membrane, and consequently in adjacent cell layers.
In addition, visual data collected using this advanced technology led researchers to suggest that dot-and-fleck lesions — which often plague Alport patients — could actually represent alterations in the RPE layer.
Taken together, this study’s findings support the conclusion that Alport patients may have localized retinal dysfunction.
“En face OCT may be useful in evaluating retinal abnormalities and understanding the underlying pathophysiology of Alport syndrome,” researchers wrote.