Optical coherence tomography of the macula in congenital achromatopsia

It is known that symptoms of congenital achromatopsia are caused by the lack of functioning cones, but there are very few published data on histologic changes in the retina in these cases. This study was conducted to examine in vivo the anatomic structure of the retina of patients with achromatopsia.

Fifteen eyes of eight patients with congenital achromatopsia and 18 eyes of nine control subjects were examined by optical coherence tomography. Radial 6-mm scans were taken of the macula. The thickness of the neuroretina was measured both automatically and manually. Measurements were taken at the foveola and at distances of 1.5 and 3 mm. Total macular volume and the retinal thickness in the nine ETDRS regions were also calculated.

In patients with achromatopsia, statistically significant reductions were found in total macular volume and in the thickness of the central retina. Remarkable differences were found between the results obtained from different methods of measuring retinal thickness. Automated methods underestimated retinal thickness compared with manual measurements.

The structure of the macula in achromats differs from that in normal subjects. A possible reason for the structural alteration is the qualitative and/or quantitative disorder of the cone photoreceptors, as the morphologic change is most expressed in the foveola. The automated methods are not always suitable for measuring retinal thickness in the foveola. The structural changes seen in the central retina of the patients could provide useful information for future gene therapy.