Optical Coherence Tomography Assessment of Apparent Foveal Swelling in Patients with Foveal Sparing Secondary to Geographic Atrophy

Geographic Atrophy and Foveal-Sparing Changes Related to Visual Acuity in Patients With Dry Age-Related Macular Degeneration Over Time

“…Until recently, GA research groups mainly focused on the atrophic region, the lesion size progression, and the junction zone between GA and healthy retina. FS is attracting increased interest because of its presumed protective effect in specifically preserving the central retina and because it is crucial for preserved VA in patients with GA. 6,7,9,10 The delimitation of residual retina in FS is challenging when conventional methods are used. 32 In previous studies, our group defined SDOCT criteria that allowed healthy and diseased tissue to be differentiated in eyes with GA. 19,21,23 We studied the impact of disease progression on the foveal region, and therefore on BCVA, by grading the area of atrophy in SDOCT volume scans over a period of 18 months along with spared areas in the 2 concentric circles (in the central millimeter and in the central 3 mm centered on the foveola) present in the ETDRS grid containing the fovea.…”

“…[4][5][6] This phenomenon is referred to as foveal sparing (FS) and is evaluated using blue light fundus autofluorescence (FAF), fundus photography, and optical coherence tomography (OCT). [6][7][8][9][10][11] The pathophysiologic background of this phenomenon is not clear, but FS in GA may be related to the high density of cones in the central retina, the possible protective effect of the macular pigment, and/or the unique choroidal blood supply of the fovea. [12][13][14][15][16] Another hypothesis is a primary dysfunction of rods in the perifoveal area, which is supported by the loss of dark adaptation in patients with AMD.…”

Foveal Sparing in Stargardt Disease

“…Because foveal sparing can be present in phenotypes that are independent of ABCA4 mutations, including AMD and mitochondrial retinal dystrophy, 6,[8][9][10][11][12]17,20,25,44,45 genetic factors other than ABCA4 mutations are likely involved. These factors could include single nucleotide polymorphisms (SNPs) and even mutations in retina-specific genes other than ABCA4, which suggests that a digenic or triallellic trait-in combination with the identified ABCA4 mutations-may underlie the degenerative pattern observed in our patients.…”

“…When forming a diagnosis, foveal sparing-associated clinical entities other than late-onset STGD should be considered, including geographic atrophy in AMD, mitochondrial retinal dystrophy associated with the m.3243A>G mutation, central areolar choroidal dystrophy, and pseudo-Stargardt pattern dystrophy. 6,9,10,27,29 Importantly, misdiagnosing this condition can lead to inappropriate genetic counseling (these diseases display unique inheritance patterns) and/or an inaccurate estimate of the prognosis. Furthermore, in the event of an incorrect diagnosis of AMD, prescribing vitamin A-rich nutritional supplements can accelerate the accumulation of all-trans-retinal-derived toxins and increase the rate of disease progression, as shown in the retinas of homozygous Abca4knockout mice.…”

“…Foveal sparing is an intriguing phenomenon in which retinal atrophy surrounds a relatively preserved fovea, leaving central visual acuity largely unaffected. Although foveal sparing has been reported in a variety of conditions, including Stargardt disease (STGD1), [3][4][5] mitochondrial retinal dystrophy associated with the m.3243A>G mutation, 6 and geographic atrophy in age-related macular degeneration (AMD), [7][8][9][10][11] its etiology remains poorly understood.…”