Within-subject assessment of foveal avascular zone enlargement in different stages of diabetic retinopathy using en face OCT reflectance and OCT angiography

Abstract

Enlargement of the foveal avascular zone (FAZ) due to progressive capillary nonperfusion is associated with visual deterioration in patients with diabetic retinopathy. The FAZ area has long been considered an important clinical marker of advancing retinopathy. However, a large body of literature shows that the FAZ area varies considerably in healthy eyes, resulting in substantial overlap between controls and diabetics, thus reducing its discriminatory value. In this study, within-subject FAZ area enlargement was obtained by the comparison of the structural FAZ area to the functional FAZ area using simultaneouslyacquired, corresponding en face OCT reflectance and OCT angiography images. Our study suggests that en face OCT reflectance images provide useful anatomic baselines of structural FAZ morphology prior to the onset of disease. Measurements of within-subject FAZ area enlargement appear to be a more sensitive method for identifying the onset of diabetic retinopathy as compared to using OCT angiographic measurements of FAZ alone.

Interocular asymmetry of foveal avascular zone morphology and parafoveal capillary density in sickle cell retinopathy

“…A representative patient with such asymmetry is illustrated in Fig 5. Greater parafoveal capillary nonperfusion is seen in the left eye compared to the right. This decrease in perfusion is particularly evident in the temporal parafovea of the more severe eye, which is consistent with previous studies [19,30]. Greater asymmetry was seen in P-SCR than in NP-SCR patients for all FAZ and global parafoveal capillary density metrics, suggesting that asymmetric differences in disease severity seen earlier in the disease course may continue to progress asymmetrically.…”

“…This type of interocular asymmetry has been documented in other conditions such as glaucoma and diabetic retinopathy [15,16], for which relationships to asymmetric upstream blood flow has been reported [17,18], However, to the best of our knowledge, no studies have quantitatively compared the severity of vascular trauma between eyes in SCR. In this study, we examined interocular asymmetry of FAZ and parafoveal capillary density metrics in SCR patients and unaffected controls using OCT-A [19,20].…”

Preservation of the Foveal Avascular Zone in Achromatopsia Despite the Absence of a Fully Formed Pit

“…While our youngest subject was 10 years old, the FAZ normally forms prenatally. 1 Thus, we cannot rule out that there was no FAZ at birth in any of our patients and that vascular remodeling (such as that occurs in diabetic retinopathy 9 ) occurred postnatally to effectively create a FAZ. The normal area of the FAZ in ACHM would argue against this, although the decreased circularity/roundness of the FAZ in ACHM could be considered consistent with this alternate interpretation.…”

“…3 This is made possible by the high density of cone photoreceptors, 4 the specialized "private line" circuitry between cones and midget ganglion cells, 5,6 and increased cortical sampling of foveal inputs in V1. 7,8 Given that foveal structure and function is affected in a wide range of retinal diseases that lead to severe visual impairment, [9][10][11][12][13] there is significant interest in understanding how the fovea develops, especially the relationship between different foveal specializations.…”

Progress in Multimodal En Face Imaging: feature introduction

“…Giselle Lynch et al [15] demonstrate that en face OCT reflectance images provide useful anatomic baselines of structural foveal avascular zone (FAZ) morphology prior to the onset of diabetic retinopathy. In this study, within-subject FAZ area enlargement was obtained by the comparison of structural FAZ area to the functional FAZ area using simultaneously-acquired, corresponding en face OCT reflectance and OCT angiography images.…”