Comparisons of size of foveal avascular zone area among children with posterior microphthalmos, high hyperopia, and normal eyes

Correlation of the macular microvasculature to the axial length in pediatric patients with high axial refractive errors

AIMS

To compare the vascular density (VD) of the macular superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC), and the foveal avascular zone (FAZ) among high hyperopic, high myopic, and emmetropic children using optical coherence tomography angiography (OCTA).

METHODS

This was a cross sectional comparative study of otherwise healthy children with different refractive errors. Patients were recruited from Cairo University Children's Hospital. OCTA imaging was performed using the RTVue XR Avanti device with AngioVue software. Both the 3 × 3 and 6 × 6 mm macular scans were utilized. Automated measurements were obtained from the built-in machine software. Axial length (AL) measurements were done using Lenstar LS 900 optical biometer.

RESULTS

Ninety eyes from 51 healthy children were included. Among high myopes, there was significant thinning of the parafovea (p < 0.001). SCP-VD was also lower in high myopes in all areas except the fovea (all p < 0.001). The DCP-VD was significantly lower in high myopes in the parafovea and perifovea. High hyperopes had lower subfoveal CC-VD. Despite high myopes showing a significantly lower OCTA signal strength, linear regression analysis revealed that AL was an independent and significant predictor for the FAZ-area, as well as parafoveal and perifoveal SCP and DCP-VD.

CONCLUSION

High myopia results in a reduction of VD in both the SCP and DCP, which can be non-invasively detected and monitored using OCTA. While lower VD may, in part, be attributed to lower OCTA image quality, our findings demonstrate that AL independently and significantly predicts macular vascular parameters on OCTA in children.

Correlation between refractive errors and ocular biometric parameters in children and adolescents: a systematic review and meta-analysis

BACKGROUND

Refractive errors are one of the most common ocular conditions among children and adolescents, with myopia showing an increasing prevalence and early onset in this population. Recent studies have identified a correlation between refractive errors and ocular biometric parameters.

METHODS

A systematic search was conducted in electronic databases including PubMed, EMBASE, Cochrane Library, Web of Science, and Medline from January 1, 2012, to May 1, 2023. Various ocular biometric parameters were summarized under different refractive states, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), corneal curvature (CC), Corneal curvature radius (CR),axial length-to-corneal radius ratio (AL/CR ratio), choroidal thickness (ChT), retinal thickness (RT), retinal nerve fiber layer thickness (RNFL), and retinal blood density (VD). The differences in these parameters among different refractive states were analyzed using Stata software with fixed or random-effects models, taking into account the assessed heterogeneity level.

RESULTS

This meta-analysis included a total of 69 studies involving 128,178 eyes, including 48,795 emmetropic eyes, 60,691 myopic eyes, 13,983 hyperopic eyes, 2,040 low myopic eyes, 1,201 moderate myopic eyes, and 1,468 high myopic eyes. The results of our study demonstrated that, compared to the control group (emmetropic group), the myopic group and low, moderate, and high myopic groups showed significant increases in AL, AL/CR ratio, and ACD, while the hyperopic group exhibited significant decreases. Compared to the control group, the myopic group had a significantly increase for CC, while CR, CCT, perifoveal RT, subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal (except nasal) ChT, and pRNFL (except temporal) significantly decreased. Compared to the control group, the hyperopic group had a significantly increase for subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal ChT, and nasal pRNFL. Compared to the control group, the low and moderate myopic groups had a significantly decreases for the CCT, parafoveal RT (except nasal), perifoveal RT (except nasal), and pRNFL (except superior and temporal). Compared to the control group, the high myopic group had a significantly increase for CR, while LT, perifoveal ChT (except nasal), parafoveal RT, perifoveal RT, and pRNFL (except temporal) had significant decreased.

CONCLUSION

The changes of ocular biometric parameters in children and adolescents are closely related to refractive errors. Ocular biometric parameters devices, as effective non-invasive techniques, provide objective biological markers for monitoring refractive errors such as myopia.

Normative Vascular Features on OCT Angiography in Healthy Nepalese Eyes

PURPOSE

To establish normative data on morphological characteristics and quantitative parameters of Foveal Avascular Zone (FAZ) as well as their systemic and ocular associations using OCT angiography (OCT-A) in healthy Nepalese subjects.

PATIENTS AND METHODS

A prospective, cross-sectional, population-based study recruiting 210 healthy samples (420 eyes) aged 10 to 70 years was conducted. All the samples underwent detailed comprehensive eye examination followed by Optical Coherence Tomography Angiography (OCTA) and Enhanced Depth Imaging performed in each eye using Spectral Domain Optical Coherence Tomography. Foveal avascular zone area and vessel density in superficial and deep retinal plexus and Sub foveal Choroidal Thickness (SFCT) were evaluated. Ocular and systemic associations of these parameters were also studied in a multivariate analysis utilizing linear regression.

RESULTS

The mean superficial and deep FAZ area was 459.96 ± 124.75 μm (95% confidence interval [CI], 443.08-476.83) and 589.0 ± 141.39 μm (95% CL, 570.77-609.02), respectively. The vessel density in superficial capillary plexus was 54.03 ± 9.34% (95% CL, 53.98-54.11) while the vessel density in deep capillary plexus was 25.91 ± 38% (95% CL, 25.85-25.96). The mean SFCT in this study was 308.89 ± 68.87μm (95% CL, 299.64-318.14 μm). There was no statistically significant inter-eye difference in the FAZ parameters. Myopic eyes had smaller FAZ, lesser vessel density and thinner SFCT. Association was observed between superficial FAZ area and systolic blood pressure, and deep FAZ area and diastolic blood pressure.

CONCLUSION

This study reports the normative data on FAZ parameters in healthy Nepalese subjects which can serve as references for interpreting these parameters in different retinal-choroidal diseases.