Abstract
Purpose: :
To test the adaptation of a Heidelberg Retina Angiograph (HRA) for objective quantification of the corneal epithelial barrier function by means of fluorophotometry.
Methods: :
A standard HRA–II was equipped with an additional front lens (focal distance 40 mm) for non–contact fluorophotometric measurements. Following ethics committee approval normal healthy volunteers (n=11), contact lens users (n=6), patients with severe dry eye (n=10) and patients after penetrating keratoplasty (n=9) were examined. After baseline measurements 40 µl of 0.5% fluorescein were instilled into the conjunctival sack. The intensity of fluorescein was measured 0, 5, 15, 30, 60 minutes after applying the dye. The data were analyzed with the Mann–Whitney–U–Test.
Results: :
In comparison with the healthy controls the intensity of fluorescein was from 5 minutes on significantly higher (p=0,002) on patients with corneal surface disease in severely dry eyes and after keratoplasty. No difference was found between the contact lens users and the control group. The method had a sensitivity of 91.7% (95%–confidence interval 77.5%–98.3%) and a specificity of 100% (95%–confidence interval 87.3%–100.0%).
Conclusions: :
A modified HRA–II can be used with good specificity and sensitivity to quantify the corneal epithelial barrier function. This widely available instrument offers a new simple, cost–efficient method for corneal fluorometry.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • cornea: epithelium • cornea: tears/tear film/dry eye