Assessment of Macular Microvasculature in Healthy Eyes of Infants and Children Using OCT Angiography

Abstract

Purpose: To assess macular vasculature in healthy infants and children using OCT angiography (OCTA).

Design: Prospective cross-sectional study.

Participants: One hundred thirty-five normal maculae of 89 healthy infants and children (mean age, 8.5±5.3 years; range, 9 weeks-17 years) treated at the Duke University Eye Center.

Methods: We imaged 135 maculae of 89 pediatric patients using the standard Spectralis tabletop and investigational Spectralis with Flex module devices, both equipped with investigational OCTA software (Heidelberg Engineering, Heidelberg, Germany). OCT angiography images of the superficial vascular complex (SVC) and deep vascular complex (DVC) were analyzed for foveal avascular zone (FAZ) area and superficial and deep vessel density. We assessed effects of age, gender, race, axial length (AL), and central subfield thickness on FAZ and vessel density. Patients with both eyes imaged were assessed for agreement between the FAZ and vessel densities of the left and right eyes.

Main outcome measures: The FAZ area, as well as vessel area density (VAD) and vessel length density (VLD) in the SVC and DVC.

Results: The FAZ varied significantly with race; white patients showed a significantly smaller FAZ than black patients (mean difference, 0.11 mm²; P = 0.004). The FAZ did not vary with age, gender, or AL (P > 0.05). In the SVC, VAD and VLD varied significantly with age (P < 0.001) and AL (R² = 0.46; P < 0.001) but not gender (P > 0.05). The SVC VLD was significantly different between races and ethnicities (P = 0.037), but VAD was not (P < 0.05). In the DVC, VAD and VLD also varied significantly with age (P < 0.001) and AL (R² = 0.46; P < 0.001) but not gender or race (P > 0.05). There was excellent agreement between the right and left eyes for FAZ (intraclass correlation [ICC], 0.97), SVC VLD (ICC, 1.00), and DVC VLD (ICC, 1.00).

Conclusions: Quantitative studies of pediatric perifoveal vasculature should consider age, race, and AL. In eyes with unilateral disease, the perifoveal vasculature in the unaffected eye may be used as a control comparison because there is excellent agreement between eyes.

Figure 1.

MATLAB (MathWorks, Natick, MA)-processed OCT angiography images of the superficial vascular complex (SVC) and deep vascular complex (DVC) of a 14-month-old infant undergoing an examination under anesthesia for persistent hyperplastic primary vitreous in the fellow eye. The original images were binarized by comparing the intensity of each pixel against a local threshold that is the average intensity of pixels inside the 7×7-pixel box centered at the pixel of interest. Then the vessel area density (percentage) was measured by calculating the percentage of the overall 10°×10° scan that was occupied by vessels, excluding the foveal avascular zone (FAZ) area. The images were also skeletonized to measure vessel length density per millimeter. The original DVC image was filtered to facilitate automatic measurement of the FAZ.

Figure 2.

Graphs showing vessel density in the superficial vascular complex (SVC) and deep vascular complex (DVC) reported in terms of both vessel area density (VAD [percentage]) and vessel length density (VLD [per millimeter]) in linear (red line) and quadratic (green line) regression models with age. For the SVC, both linear and quadratic models were significantly predictive of VAD and VLD (P < 0.001 for all). The relationship between age and vessel density (VAD and VLD) was better fit when using the quadratic (adjusted R² = 0.57 and adjusted R² = 0.54, respectively) rather than linear model (R² = 0.38 and R² = 0.27, respectively). For the DVC, the linear and quadratic regression models were a poor fit for both VAD (linear R² = 0.10, quadratic adjusted R² = 0.27) and VLD (linear R² = 0.03, quadratic adjusted R² = 0.27), indicating that although age significantly predicted the DVC VAD and VLD (P < 0.001, quadratic fit), most of the variation in the data was not explained by age.