Abstract
Purpose: :
Since dry eye syndrome has been observed either before the onset of blepharospasm or with blepharospasm, it has been thought that dry eye might trigger the onset of the disease. The aim was to characterize tear distribution on ocular surface on patients with Blepharospasm using optical coherence tomography (OCT).
Methods: :
Six patients with primary Blepharospasm (12 eyes) and three normal controls (6 eyes) were recruited. The tears on ocular surface along with the central vertical line were imaged using a custom built corneal OCT. OCT images were taken before (baseline), immediately after instillation of a drop of artificial tears (GenTeal, Ciba) and at 10 minutes. The subjects were asked to hold their eyes open as long as they can during OCT imaging. Eight to twelve images before and after blinks were processed to yield the results using custom software. Processed variables included central tear film thickness and tear meniscus height, curvature and area at upper and lower eyelids. Non–invasive tear breakup time was measured using a Keeler tearscope.
Results: :
At baseline, significantly greater lower tear meniscus was found in patients (t–test: p<0.05 of all parameters of lower tear meniscus), although no significant differences of tear film thickness and parameters of upper tear meniscus were found (t–test: p>0.05). The patients had shorter NITBUT measured at baseline (t–test: p<0.01). Immediately and 10 minutes after instillation of artificial tears, greater increase of lower tear meniscus and tear film thickness were found significantly in patients (t–test, p<0.05).At 10 minutes, thicker tear film thickness was found in patients compared to controls (t–test: p<0.05), although there was no significant difference immediately after instillation.
Conclusions: :
Blepharospasm patients have increased lower tear meniscus and shorter NITBUT. Large lower tear meniscus and thick tear film in patients after instillation of artificial tears might relate to weak lid action (to clear the tears) during blinking or poor drainage system.
Keywords: cornea: tears/tear film/dry eye • anterior segment • image processing