Table 1.

Quartiles and functional fits of the vessel geometric parameters

	25th percentile	50th percentile	75th percentile	Curve fit models		Fitted parameters
Length (μm)	22	38	66	Lognormal	$\frac{1}{x\sigma \sqrt{2\pi }}{e}^{-\frac{{(\ln x-\mu )}^2}{2{\sigma }^2}}$	μ = 3.6; σ = 0.8
Tortuosity	1.02	1.06	1.14	Exponential	$\lambda e^{-\lambda (x-x_0)},x_0=1$	λ = 11
Inclination (deg)	39	60	78	Logistic	$\frac{L}{1+e^{-k(x-x_{50})}}$	L = 0.04; x50 = 21; k = 0.12
Polar orientation (deg)	20	43	67	Uniform	$\frac{1}{x_{\max }-x_{\min }}$	xmin = 0; xmax = 90

For reference, the LC is about 3500 μm in diameter, 300 μm in thickness, and about 600 μm from top to bottom (height is larger than thickness because the LC is curved). This means that the median vessel segment is about 1% of LC diameter and 12% of its thickness [45]. Tortuosity varies from 1 for a straight segment to infinity. For comparison, vessels in the porcine ONH have tortuosities from 1 to 1.35 [2]. In terms of the interpretation of the fitted parameters: the logistic model is a function to generate an S-shaped curve, where x₅₀ is the x value of the midpoint, k is the steepness of the curve, L is the maximum value of the curve. The parameters x_min, x_max of the uniform model are values at the extremes of the range.