In patients with idiopathic foveal hypoplasia (IFH), vascular density, skeletal density, and fractal dimension are reduced at the superficial capillary plexa (SCP) and deep capillary plexa (DCP) levels, according to findings from a group of researchers in France. Optical coherence tomography angiography (OCT-A) may be used to analyze these specific anatomical and vascular characteristics to evaluate the severity of IFH.
Foveal hypoplasia is characterized by an abnormal anatomical absence of the foveal pit. In some cases, foveal hypoplasia can be isolated and found in patients with normal visual function. Isolated foveal hypoplasia is also known as idiopathic foveal hypoplasia. Because patients with IFH often have good visual acuity, the relationship between the presence of a foveal pit and visual function begged further examination, according to researchers. While fluorescein angiography reveals a reduced foveal avascular zone in eyes with IFH, it enables the visualization of only 1 of 3 capillary plexa, according to investigators. OCT-A produces high-resolution images of the retinal microvasculature, including the SCP, DCP, and intermediate capillary plexa.
Researchers sought to evaluate vascular density, fractal dimension, and skeletal density using OCT-A in the eyes of patients with IFH. To conduct this retrospective consecutive observational case series, patients presenting with IFH between January 2015 and October 2018 were age-matched to healthy controls. A pair of graders classified eyes as having IFH. Both IFH and healthy subjects received comprehensive ophthalmic exams, including spectral domain OCT and OCT-A. Eyes with epiretinal membranes and those with difficulties in fixation were excluded.
In total, 36 eyes of 21 patients (18 eyes with IFH, n=9 patients, and 18 healthy control eyes, n=11 patients) were included. The mean age was approximately 62.8 years in patients with IFH and 68.6 years in healthy patients (P =.17). Researchers found a decrease of vascular density at the level of the SCP and DCP in eyes with IFH compared with healthy control eyes (P =.005 for VD at the level of the SCP and P =.003 for VD at the level of the DCP, respectively). On the central 1 mm2, VD was decreased in healthy eyes (32.3% ± 4.8) at the level of the SCP compared to IFH eyes (55.6% ± 46.3) (P <.001). Skeletal density was decreased in IFH eyes in both SCP and DCP (P <.001). Fractal dimension was lower in IFH eyes in both SCP and DCP (P <.001).
Investigators note several limitations to their study, including its small sample size and the lack of data concerning axial length.
Le HM, Souied EH, Pedinielli A, et al. Idiopathic foveal hypoplasia: quantitative analysis using optical coherence tomography angiography. Retina. 2020;40(12):2325-2331. doi:10.1097/IAE.0000000000002777.