Researchers have shown for the first time how cells across different tissue layers in the eye are affected in people with choroideremia – a rare genetic disorder that leads to blindness. The researchers combined traditional eye imaging techniques with adaptive optics, a technology that improves imaging resolution.
The researchers used adaptive optics and indocyanine green dye to view live retinal cells, such as light-sensing photoreceptors, retinal pigment epithelium (RPE), and choroidal blood vessels. They could see in great detail how choroideremia disrupts these tissues, which could aid in developing effective treatments for this and other diseases. The RPE of the retina is a layer of pigmented cells necessary for photoreceptor nourishment and survival.
Choroideremia affects men more than women because the disease-causing gene is on the X chromosome. Because men have only one copy of the X chromosome, a gene mutation causes males to develop more severe symptoms. Females, who have two copies of the X chromosome, usually have milder symptoms, as they have one working copy of the gene on the other X chromosome.
The RPE cells in males and females with choroideremia are dramatically enlarged. Female participants in the study showed a mix of enlarged and healthier-looking RPE cells. It may explain why women with choroideremia have milder symptoms.