People with Alport syndrome who do not have the eye abnormalities usually found in this disease may still have a significantly smaller diameter in the crystalline lens and poorer lens power, a study in seven patients reports.
Researchers suggest that these might be signs for ophthalmologists that support an early diagnosis of the condition, especially when genetic testing is not available.
The study, “Alport Patients without Classic Ocular Symptoms Have Smaller Lens Diameter” was published in Medical Science Monitor.
Alport syndrome is characterized by progressive kidney disease, hearing loss and eye abnormalities like dot-and-fleck retinopathy, but symptoms evident in many patients are limited to blood and protein in the urine.
The disease can be diagnosed by a genetic test, urine test, kidney or skin biopsy, and vision screening.
Genetic testing is generally replacing more invasive diagnostic approaches like biopsies, but examining a small amount of tissue under a microscope (a biopsy) remains the first-line diagnosis procedure in different parts of the world.
Researchers at the University of Debrecen in Hungary studied the presence of ocular symptoms in Alport patients while looking for early signs of the disease to help improve and speed its diagnosis.
They examined the eyes of seven recently diagnosed Alport patients (two men and five women, mean age of 29), paying special attention to changes on the crystalline lens — which focuses light that enters the eye — and the retina, the back portion of the eye that senses light and converts it into neural signals sent to the brain for visual recognition.
These patients were compared to seven healthy subjects (one man and six women, average age 29.6 years). All patients underwent kidney biopsy, and tissue analysis results were all consistent with Alport syndrome.
Typical ocular symptoms were observed in one patient, an 18-year-old woman. She had unusual yellowish and/or whitish flecks or dots of pigment on the retina (dot-and-fleck retinopathy) and cellular changes in her cornea consistent with posterior polymorphous corneal dystrophy (PPMD), both often seen in Alport syndrome. She also had blurry vision at all distances (astigmatism), great difficulty seeing objects in the distance (myopia), and a family history of the disease.
All patients had blood and protein in their urine. People with Alport also had a significantly smaller lens diameter and a lesser lens power in comparison to the control group. They also tended to have thicker lenses than controls, but this difference was not significant.
No differences were found in terms of visual acuity (clarity or sharpness of vision) between study and control groups. Compared to healthy individuals, patients appeared to have myopia, but the difference again was not significant.
Results indicate that thicker, smaller lenses (spherophakia) may a first sign of Alport syndrome, which can be diagnosed by ultrasound biomicroscopy, a non-invasive imaging of the anterior part of the eye.
“This finding also underlines the importance of ophthalmological testing in possible Alport patients, which, combined with ultrasound biomicroscopy, might be a diagnostic tool for the screening of patients with kidney abnormalities,” the team concluded.
These researchers recommend that doctors not only look for the classical signs of the disease, but also explore their patients’ crystalline lens size, particularly if genetic testing is not an option.