Abstract
Purpose:
Recently, the optical coherence tomography (OCT) reflectivity of intra- or subretinal fluid (SRF) has attracted the interest of researchers evaluating retinal diseases; however, it is unclear which components affect OCT reflectivity. We studied the relationship between blood components and OCT reflectivity using an animal model in which aqueous humor was substituted with different experimental solutions without changing the integrity of the retina.
Methods:
The aqueous humor of an enucleated swine eye was replaced with plasma obtained from healthy volunteers. The OCT reflectivity of the anterior chamber filled with each plasma was calculated from individual OCT images, and was expressed by an arbitrary unit (AU). The concentration of blood components such as cholesterol, hemoglobin, and bilirubin of each individual was measured, and the correlation between each of them and the OCT reflectivity of aqueous humor in an enucleated swine eye was analyzed. Using the same model, the effects of the single plasma component, which was diluted in a balanced salt solution (BSS), on OCT reflectivity was examined. The examined components involved albumin, bilirubin, fibrinogen, γ-globulin, hemoglobin, and triglyceride. The concentration corresponded to the normative database.
Results:
Blood samples were obtained from 24 individuals. CT reflectivity was 30.68 +/- 14.8 AU (average +/- SD), ranging from 11.11 to 60.31 AU. OCT reflectivity correlated significantly with the concentration of triglycerides (R=0.634, P=0.001) and total cholesterol (R=0.488, P=0.015) using Spearman’s rank correlation coefficient. While a partial correlation analysis showed that it correlated significantly with triglyceride (R = 0.60, P =0.003), but not total cholesterol. OCT reflectivity was highest in a BSS with hemoglobin (average 42.05 AU), followed by fibrinogen (8.08 AU), bilirubin (6.12 AU), and γ-globulin (2.85 AU). Albumin did not increase the reflectivity of the BSS with a normal concentration (0.73 AU) compared to the control balanced salt solution alone (1.36 AU). Because triglyceride was not dissolved in BSS, reflectivity was not increased (0.41 AU).
Conclusions:
OCT reflectivity was most strongly affected by the presence of triglyceride among the blood components of healthy individuals. Some molecules such as hemoglobin and fibrinogen significantly increase OCT reflectivity. This information is helpful for interpreting OCT findings correctly.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
550 imaging/image analysis: clinical