A novel case of CNGA-3 achromatopsia: Structural changes seen over time

Author(s):

Contrary to the traditional understanding that this disorder remains stable, long-term structural changes were observed through spectral-domain optical coherence tomography (SD-OCT) imaging.

(Image Credit: AdobeStock/Alessandro Grandini)

Investigators reported long-term structural changes observed on spectral-domain optical coherence tomography (SD-OCT) images in patients with cyclic nucleotide-gated channel subunit alpha 3 (CNGA-3)-related achromatopsia. This finding is in contrast to the conventional notion that the disorder remains stable, according to Haaris Khan, MD, first author of the study. He is from the University of British Columbia, Vancouver, British Columbia, Canada.

The investigators reported the case of a 16-year-old girl who was followed annually over 10 years. The follow-up included obtaining annual SD-OCT images. Genetic testing confirmed the diagnosis of achromatopsia, which showed heterozygosity for the CNGA3 gene. Her clinicians measured her best-corrected visual acuity (BCVA) and evaluated the structural changes in the fovea of the hyperreflective external limiting membrane, ellipsoid zone disruptions, optically empty spaces, choroidal hypertransmission defects, and hyperreflective foci.

The investigators reported that over the 10 years of evaluation, the BCVA was stable; however, in the fovea, they saw “progressive structural changes” on the images. The first changes were the hyperreflective external limiting membrane and a disrupted ellipsoidal zone.

Optically empty spaces were then visualized; which indicated loss of the photoreceptors, deficits in choroidal hypertransmission, and hyperreflective foci present in the outer nuclear layer and the ellipsoidal zone, they reported.

They commented that the findings in this case were contrary to the belief that achromatopsia is a static disease.

Khan pointed out, “Despite the stable BCVA, long-term structural changes were seen in OCT imaging. The progressive disruption of the ellipsoidal zone, the appearance of hyperreflective foci and optically empty spaces indicate the progressive nature of the disease. To our knowledge, this is one of the longest follow-ups reported in literature.”