The Sparkle of the Eye: The Impact of Ocular Surface Wetness on Corneal Light Reflection

PURPOSE: To measure the sparkle of the human eye evaluated by the intensity of corneal light reflection in normal subjects and dry eye patients to investigate whether ocular surface wetness has an impact on the sparkle of the eye. DESIGN: Prospective case-control study. METHODS: We examined a consecutive series of eight dry eye patients with Sjogren syndrome (SS, 15 eyes), as well as eight normal subjects (16 eyes). The specular corneal surface light reflection was quantitatively measured with an ophthalmic slit-lamp microscope and image capturing system under fixed conditions of light source, incident angle, and detector sensitivity. The intensity of images from subjects' corneal light reflection was quantified with image analysis software along with the measurement of grade of self-reported brilliancy of the eye, corneal fluorescein staining score, tear film break-up time, and Schirmer test value. The intensity of corneal light reflection was also compared before and after dry eye treatment. RESULTS: The mean intensity of corneal light reflection was significantly lower in dry eye patients (125.0 +/- 40.1) than normal subjects (167.6 +/- 36.6, P = .004). Grade of self-reported brilliancy of the eye, corneal fluorescein staining scores, tear film break-up time, and Schirmer test values showed good correlation to the intensity of corneal light reflection. After punctal plug treatment, the intensity of corneal light reflection significantly increased from 125.0 +/- 40.1 to 167.2 +/- 45.0 (P < .0001). CONCLUSIONS: The intensity of corneal light reflection representing the sparkle of the eye was significantly more intense in normal subjects compared to dry eye patients, and was increased after punctal plug treatment. The intensity of corneal light reflection appeared to correlate well with tear film stability, volume, and ocular surface desiccation. We showed that tears contributed not only to ocular surface wetness but also to the extent of the light reflection from the eye. (Am J Ophthalmol 2011;151:691-696. (C) 2011 by Elsevier Inc. All rights reserved.)