Bulbar conjunctival microcirculation and microvascular network in habitual contact lens wearers

Abstract

Purpose : This study was to investigate the morphometry and hemodynamics of the bulbar conjunctival microvasculature between habitual contact lens wearers and non-contact lens wearers.

Methods : Custom built Functional Slit-lamp Biomicroscope (FSLB) was used to image the temporal bulbar conjunctiva of contact lens wearers and non-contact lens wearers. All of the measurable venules were processed to yield vessel diameters and blood flow velocities. Fractal analysis using box counting (D_box) and multifractal analysis (D₀) representing microvascular network density and complexity was used to quantitatively analyze microvascular network. Ten habitual contact lens wearers (5 males, 5 females, age 25.7 ± 5.3 yrs) and 20 non-contact lens wearers (10 males, 10 females, age 29.6 ± 4.9 yrs) were enrolled. The average contact lens wearing history for habitual contact lens wearers was 9.1 ± 3.9 yrs (range: 3 to 16 years).

Results : The averaged blood flow velocity of habitual contact lens wearers was 0.81± 0.24 mm/s, which was significantly faster than non-contact lens wearers (0.47 ± 0.15 mm/s, P < 0.001). However, microvascular network density and complexity (D_box = 1.63 ± 0.04, D₀ = 1.62 ± 0.05) in contact lens wearers were not different compared to that (D_box = 1.69 ± 0.03, D₀ =1.68 ± 0.05) in non-contact lens wearers (both P > 0.05). There was no significant difference in vessel diameter between contact lens wearers(16.5 ± 2.3 µm) and non-contact lens wearers (17.3 ± 1.7 µm, P > 0.05).

Conclusions : Although there was no difference in microvascular network between two groups, increased blood flow velocity in habitual contact lens wearers indicates the vascular responses to contact lens, which may have a protective mechanism for successful lens wear.Future longitudinal studies with large sample sizes may validate the view point.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.