Amblyopia is a common ophthalmic disease in children. Although eye examination does not show any organic lesion, the corrected visual acuity cannot reach the normal level. During the critical period of visual development, children are prone to amblyopia due to binocular abnormal action or form stripping. The incidence of amblyopia in China is 2–4% [
Optical coherence tomography angiography (OCTA) is a new ophthalmological imaging method, which is applied to the vascular imaging of the retina, choroid, and optic nerve. Compared with traditional fundus angiography, OCTA has the advantages of being noninvasive and fast, offers high-resolution and three-dimensional imaging, and can more accurately measure the size of capillary non-perfusion area and neovascularization [
Thirty-two children with monocular hyperopic anisometropia and severe amblyopia who were treated in the Department of Ophthalmology of the First Affiliated Hospital of Gannan Medical College from January 2020 to December 2020 were included in the study. Eyes with amblyopia (
All selected patients underwent comprehensive ophthalmologic examination including slit lamp, eye position, visual acuity, optometry, eye movement, intraocular pressure, ocular axis, and fundus examination; all kinds of organic lesions were excluded. Moreover, the general indices of all candidates were recorded and analyzed, including age, sex, visual acuity, intraocular pressure, equivalent spherical optometry, and axial length. Objective optometry under the condition of ciliary paralysis was performed according to the expert consensus on the prevention and treatment of amblyopia in children (2021 Chinese Edition).
All included children were examined by the same experienced doctor for OCTA examination. The examination procedures were fully explained to the children at the start, and their cooperation was obtained. In this study, all subjects were performed by the AngioVue OCTA tester (OPTOVUE, USA), and ImageJ software was used to analyze all data. In this study, OCTA adopted a
(a) Superficial vessel density of macula. (b) Inner thickness of macula, defined as the distance between the internal limiting membrane (ILM) and inner plexiform layer (IPL). (c) Full thickness of macula, defined as the distance from the ILM to the retinal pigment epithelium (RPE). The parafoveal and the foveal rim were divided into the upper, lower, nasal, and temporal quadrants. The macula was divided into nine regions, and their thickness values were displayed, respectively.
SPSS21.0 software (IBM Corporation, Armonk, NY, USA) was used for statistical analysis, and the quantitative data in accordance with normal distribution were expressed as the
This study included 32 children (64 eyes, 18 male and 14 female) with monocular hyperopic anisometropia and severe amblyopia. Thirty-two eyes with amblyopia were included in the study group, and 32 contralateral healthy eyes were included in the control group. The mean age of the children was
Characteristics of eyes with amblyopia and healthy eyes.
Characteristic | Amblyopia eyes ( | Healthy eyes ( | ||
---|---|---|---|---|
Best-corrected visual acuity | 45.28 | <0.001 | ||
Mean intraocular pressure (mmHg) | 0.407 | 0.687 | ||
Spherical equivalent refraction (D) | 15.55 | <0.001 | ||
Length of optic axis (mm) | 7.219 | <0.001 |
The vessel density of macular OS, II, OI, OT, and SCP in amblyopic eyes was lower than that in the control eyes (
Comparison of superficial vessel density at different locations between eyes with amblyopia eye and healthy eyes.
Location (%, | Amblyopia eyes ( | Healthy eyes ( | ||
---|---|---|---|---|
IS | 1.946 | 0.061 | ||
OS | 5.988 | <0.001 | ||
IN | 2.063 | 0.048 | ||
ON | 1.851 | 0.074 | ||
II | 4.313 | <0.001 | ||
OI | 3.368 | 0.002 | ||
IT | 1.816 | 0.079 | ||
OT | 12.158 | <0.001 | ||
C | 11.950 | <0.001 |
SD: standard deviation; IS: inner superior; OS: outer superior; IN: inner nasal; ON: outer nasal; II: inner inferior; OI: outer inferior; IT: inner temporal; OT: outer temporal; C: central.
Results of superficial vessel density at different locations between amblyopia eye and healthy eye control (
The RT in the inner layer of macular OT in amblyopic eyes was thicker than that in the control eyes (
Comparison of macular retinal thickness at different locations between amblyopia eye and healthy eye controls.
Location | Amblyopia eyes ( | Healthy eyes ( | ||
---|---|---|---|---|
Macular inner retinal thickness ( | ||||
IS | 1.305 | 0.201 | ||
OS | 0.181 | 0.857 | ||
IN | 0.469 | 0.643 | ||
ON | 1.806 | 0.081 | ||
II | 1.238 | 0.225 | ||
OI | 1.341 | 0.190 | ||
IT | 1.848 | 0.074 | ||
OT | 8.057 | <0.001 | ||
C | 1.240 | 0.224 | ||
Macular full retinal thickness ( | ||||
IS | 8.965 | <0.001 | ||
OS | 8.790 | <0.001 | ||
IN | 7.550 | <0.001 | ||
ON | 12.386 | <0.001 | ||
II | 6.711 | <0.001 | ||
OI | 7.282 | <0.001 | ||
IT | 7.660 | <0.001 | ||
OT | 7.313 | <0.001 | ||
C | 8.185 | <0.001 |
SD: standard deviation; IS: inner superior; OS: outer superior; IN: inner nasal; ON: outer nasal; II: inner inferior; OI: outer inferior; IT: inner temporal; OT: outer temporal; C: central.
Results of macular retinal thickness at different locations between amblyopia eye and healthy eye controls (
In the past, OCT was usually used to study retinal thickness, but OCT cannot detect changes to the retinal microcirculatory system. With the continuous development of medical imaging technology, magnetic resonance imaging (MRI), functional MRI (fMRI), OCT, and OCTA are now commonly used to study amblyopia. In particular, OCTA technology has recently emerged and played a revolutionary role in the study of retinal microvascular system [
Recent studies [
Our results showed that in the study of retinal SCP vessel density in children with monocular hyperopic anisometropic amblyopia, the SCP vessel density in amblyopic eyes was significantly lower than that in contralateral healthy eyes in the macular OS, II, OI, OT, and C regions; however, there were no significant intergroup differences in SCP vessel density in the macular IS, IN, ON, and IT regions. This study also found that the inner layer RT of macular OT in amblyopic eyes was significantly higher than that in the contralateral healthy eyes, while the inner layer RT in the remaining eight regions only showed minor changes, but these changes were not significantly different between the two groups. The full-layer RT in nine macular regions of amblyopic eyes was thicker than that of contralateral healthy eyes, and the difference was statistically significant. At present, most studies on retinal vessel density and RT of amblyopia have not been classified according to the type of amblyopia and refractive state. The etiology of amblyopia and refractive state may affect the retinal vessel density and RT.
In this study, OCTA was used to analyze the retina of children with severe amblyopia caused by monocular hypermetropia, and the results were more comparable, which may be why our results are distinct from other studies. At present, most researchers study the average thickness and mean vessel density of the macular fovea, and few scholars subdivide the macular region into nine regions for comparative analyses. The decrease of vessel density in amblyopic eyes may indicate that these eyes need less nutrition to receive retinal artery blood supply, resulting in abnormal macular fovea development and retardation in amblyopic eyes. Because the nasal side of the retinal vascular system develops earlier than the temporal side and the microcirculation in different regions is not uniformed, we thought it was more meaningful to subdivide the macula into nine regions in this study.
Our study has some limitations. First, the sample size of the study is small. Second, the data accuracy was affected by the poor matching degree detected by OCTA in children. Third, the control group of myopic anisometropic amblyopia and other types of amblyopia have not been established at the same time. Fourth, the effects of equivalent spherical lens and ocular axis on retinal vessel density and retinal thickness cannot be excluded. Last, the current OCTA technique cannot detect the vessel velocity of retinal microcirculation and the elasticity and diameter of the microvessels.
In conclusion, the emergence of OCTA technology has significant advantages to study the retinal microvascular system changes. The clinical application of OCTA may have a certain exploration value in the pathogenesis, diagnosis, and treatment of amblyopia and is expected to play an important role in its diagnosis and treatment.
The data can be found at OCTA Article original data of figure files.
The authors declare that they have no conflicts of interest.