Researchers employed optical coherence tomography angiography (OCT-A) to determine that the vessel densities (VD) of nasal, inferior-nasal, inferior-temporal, superior-temporal and superior-nasal radial peripapillary capillaries (RPC) are positively correlated with large vertical cup/disc ratio (CDR). They also identified that the VDs of the inferior-nasal and temporal peripapillary regions are marginally lower in patients with juvenile ocular hypertension (JOHT), according to a cross-sectional study published in BMC Ophthalmology.
The researchers wanted to evaluate RPC and the macular VD of the superficial retinal vascular plexus (SVP) to help clinicians know when and whether they can use OCT-A to evaluate the VD in JOHT.
The team recruited study participants at the glaucoma clinic of the Eye, Ear, Nose, and Throat Hospital of Fudan University in Shanghai and provided each an eye exam that included the following tests: slit-lamp biomicroscopy, best-corrected visual acuity (BCVA), refractive error, intraocular pressure (IOP), axial length (AL) and central corneal thickness (CCT), A-scan ultrasound, dilated fundus examination, standard automated perimetry (SAP), spectral-domain optical coherence tomography (SD-OCT) and OCT-A. They also calculated their mean arterial pressure (MAP) and the mean ocular perfusion pressure (MOPP).
The researchers evaluated patients between 3 years and 40 years old who had normal open-angles on gonioscopy, a BCVA greater than 12/20, AL larger than 26.50 mm and refractive error less than -6.00 D, average RNFL and ganglion cell complex (GCC) thickness, and at least 2 reliable normal visual fields. The researchers excluded any subject with previous intraocular surgeries, nonglaucomatous optic neuropathy, retinopathies or secondary elevated IOP, hypothyroidism, cardiovascular diseases, or diabetes mellitus.
The researchers examined 86 eyes of 45 control subjects (who had normal optic disc and IOP lower than, or equal to, 21 mm Hg with no history of elevated IOP and 65 eyes of 34 patients with JOHT using OCT-A scans to quantify the VD of both the optic disc and the macula. They compared the 2 groups’ radial peripapillary capillaries vessel density (RPC-VD) and the superficial vascular plexus vessel density (SVP-VD) in perifoveal regions.
Corrected IOP of subjects with JOHT was higher than that of the subjects in the control group (P <.001) and the VD of the inside disc was lower in subjects with CDR larger than 0.6 (r = -13.304, P <.001). Average RPC-VD and nasal, inferior nasal, inferior temporal, superior temporal and superior nasal regions of RPC-VD strongly correlated positively with CDR less than 0.6 (r = 2.621, P < .001; r = 4.425, P <.001; r = 3.11, P <.001; r = 2.153, P =.001; r = 1.642, P =.019; r = 2.463, P =.006, respectively). The only region that did not show correlation with CDR was the temporal region (r = .926, P =.152). The superior and nasal of SVP-VD were somewhat lower in subjects with high IOP (r = -1.877, P =.023; r = -1.693, P =.049).
“OCT-A proves the difference of capillary VD caused by high IOP in JOHT subjects and could serve as a precise method to monitor disease development, although longitudinal data are still needed to fully evaluate this possibility,” the researchers said.
The main limitation of the study was its small sample size, particularly of subjects with JOHT who experienced both high IOP and normal CDR, the researchers said.
Chen X, Wang X, Hu X and Sun X. The evaluation of juvenile ocular hypertension by optical coherence tomography angiography. BMC Ophthalmology. 2020; Published online October 21, 2020. doi.org/10.1186/s12886-020-01641-4