Purpose
To demonstrate the feasibility of quantitative analysis of microvascular network of the lid wiper area of the human eye imaged with our functional slit-lamp biomicroscopy (FSLB).
Methods
FSLB was adapted from a traditional slit-lamp microscope by attaching a digital camera to image the conjunctiva to take images of the lid wiper area, which were compared to the images of the tarsus. Nine human subjects including 3 habitual contact lens wearers were imaged twice at one visit. Only the left eye was imaged. Custom software for automated segmenting the microvascular network has been developed and described in our previous publication (Jiang et al. Microvascular Research, 2014;92:62-71). The same software was used to segment the microvascular network of the lid wiper and tarsus. We used the fractal analysis toolbox from Benoit™ (TruSoft Benoit Pro 2.0, TruSoft Inc., St. Petersburg, FL) to analyze the fractal dimension of the microvascular network. Multifractal analysis (D0) was performed to quantify the fractality (density and complexity) of the vascular network of the lid wiper area (Fig. 1) and the tarsal conjunctiva (Fig. 2). The coefficient of repeatability (CoR) of the tests was analyzed.
Results
D0 of the lid wiper area was 1.556 ± 0.209 (mean ± SD) for the first session and 1.572 ± 0.213 for the second session. The CoR of these measurements was 7.7%. D0 was 1.358 (SD: 0.213) in contact lens wearers and 1.667 (SD: 0.116) in healthy subjects (P = 0.057). D0 of the tarsus was 1.706 ± 0.053 for the first time and 1.709 ± 0.053 for the second time. The CoR of these measurements was 3.5%. D0 was 1.703 (SD: 0.005) in contact lens wearers and 1.719 (SD: 0.064) in healthy subjects (P = 0.246). The difference of the microvascular network was significant (P = 0.046) between the lid wiper and tarsus.
Conclusions
This is the first time to demonstrate the feasibility of quantitatively analyzing the microvascular network of the lid wiper area and the tarsal area using FSLB. Further studies will need to be done on a large sample of subjects and patients with diseases and conditions. The approach could be applied to study dry eye, contact lens wear and other ocular surface diseases involving the damage and inflammation of the lid wiper and tarsal conjunctiva.