The Quantification of Retinal Vein and Artery Trajectories Using Second-Order Polynomial Equation in Eyes with Diabetic Retinopathy

PURPOSE: To quantify retinal artery and vein trajectory alterations using a quadratic polynomial model, which may reveal associations with diabetic retinopathy (DR) severity and HbA1c levels.
METHODS: To quantify the retinal artery and vein trajectory in diabetic retinopathy using the quadratic polynomial equation. The ideal curves of the right (OD) and left (OS) eyes for the retinal artery (RA) and vein (RV) trajectories were determined. The transformed coordinates were applied to a quadratic polynomial (ax2/100 + bx + c) equation. The coefficient 'a' denotes the curvature of the vascular path; decreased values reflect steeper curves, which may be associated with retinal retraction or tractional changes.
RESULTS: The analysis involved 334 eyes of 167 patients, 74 males and 93 females, with a mean age of 58.1 years (34-76 years). Background, Preproliferative, and Proliferative Diabetic Retinopathy (BDR, PPDR, PDR) were assessed. HbA1C levels were higher in PDR than in BDR (p<0.05). RAT in OD "a" values were higher in control than BDR, PPDR, and PDR. (p<0.05) Retinal vein trajectory (RVT) in OD values was lower in PDR (p=0.031). Positive correlations existed between HbA1C levels and "a" value of RAT in OS and the mean value of RAT for both eyes in PDR (r=0.737, p=0.002; r=0.669, p=0.006).
CONCLUSION: These alterations in RAT, particularly in PDR, may reflect underlying tractional forces and could potentially serve as non-invasive markers of disease severity. However, further research is needed to fully understand their clinical implications and relationship with the HbA1C level.