Why the macula?

Abstract

The regional susceptibility of the retina to diseases has been well known by clinicians for many years. It is surprising that the implications of these observations have not spawned major research efforts to characterise the structural and functional attributes of the outer retina in different regions of a foveate retina. Without such an effort, the understanding of the disease mechanisms in retinal dystrophies will remain limited and may hamper therapeutic efforts. That outer retinal disease is responsible for over 50% of blind registration in the western world underlines the importance of these considerations.

Fig. 1

Blue reflectance images of the right (a) and left (b) eyes in a patient with Type 2 macular telangiectasis showing scatter in a well-defined area centred on the fovea. Photoreceptor loss will occupy this area over time but will not extend beyond it.

Fig. 2

Autofluorescence image of the right macula (a) and left macula (b) of a patient with Bulls eye dystrophy due to mutations in the ABCA4 gene. A dark ring round the fovea indicates loss of RPE with surrounding heightened autofluorescence implying RPE stress.

Fig. 3

Autofluorescence images of the right eye of a patient with a A3243G mitochondrial mutation showing loss of RPE as dark patches circumferentially distributed in the macula and diffuse changes of RPE as speckled change over a wider area (a). Five years later, the areas of RPE loss have extended but the fovea has survived (b). A similar appearance is seen in the left eye (c).

Fig. 4

Autofluorescence of a left eye with geographic atrophy as a manifestation of age-related macular disease showing atrophy of the RPE round the fovea and evidence of RPE stress as irregular autofluorescence with sparing of the fovea.

Fig. 5

Autofluorescence of right and left eye images of a patient with Stargardt disease due to mutations in the ABCA4 gene showing RPE loss as dark patches round the fovea with prominent foveal sparing and more widespread RPE abnormality manifest as irregular autofluorescence (a, b).

Fig. 6

Autofluorescence image of the left eye of a patient with a 172 mutation in the PRPH2 gene showing absence of RPE as a juxta foveal dark patch with irregular autofluorescence extending to the optic disc indicating RPE stress.

Fig. 7

Autofluorescence image of the left eye of a patient with autosomal dominant Best disease due to a mutation in the VMD2 gene showing accumulation of autofluorescent material at the fovea. Elsewhere the autofluorescence appears normal.

Fig. 8

NR2E3. Autofluorescence images of the right and left eyes in a patient with early retinitis pigmentosa due to a mutation in the NR2E3 gene showing atrophy in an arc at 12 -20⁰ of eccentricity in the temporal fundus (a, b).