Compare of performance of two brands of Lissamine green strips : the difference between two brands of Lissamine green dye to determining their staining ability in cornea, conjunctiva, Lid wiper and presenting Marx line

Abstract

Background Ophthalmic dyes are organic compounds widely used for diagnostic purposes. Lissamine Green (LG) is a vital dye with ability to stain ocular surface epithelial cells, unprotected by mucin or glycocalyx, also LG stains damaged cells. In European clinics GREEN GLO HUB LG strips were popular in past years but has recently been replaced by I-DEW GREEN strips. However, the staining ability of the new strips has been questioned. The purpose of this study was to compare the performance of two brands and in distinguishing staining of anterior surface and lid margins. Methods The cross over, randomized and comparative study was performed in 45 patients, in two consecutive days. One brand of LG was applied to one eye and the other brand to the other eye. The second day, the brands were switched to opposite eyes. Ocular surface disease index (OSDI) questionnaire was answered prior to the examination. The LG strips (1.5 mg concentration per strip) were diluted by a drop of sterile saline before a single controlled instillation in each eye. Two minutes after applying LG, OCULUS keratograph M5 was used for taking digital photos from nasal and temporal conjunctiva, cornea and the everted lower lids. The photos were then anonymized before grading of corneal and conjunctival staining and grading of lid wiper epitheliopathy (LWE). Marx line appearance was recorded as present or absent. Burning sensation was recorded from 0(no sensation) to 3(severe sensation) based on the patients’ subjective opinion. Results In this study, there is a significant difference in ocular surface staining between the two brands of LG p=2.46 e-05 (p < 0.001). The mean value for Oxford grading of the ocular surface for LG1 was 0.74 and for LG2 was 0.046. In grading of the LWE for LG1 27.89% had grade 1 or above. For LG2 none of the photos showed any LWE, so all of them graded as 0. Also, none of the photos with LG2 showed Marx line, whereas 60.46% showed Marx line with LG1. In subjective reporting of burning sensation there was no significant mean difference between the two brands of LG (p=0.4309). Discussion This study showed that there is significant difference in staining performance between two brands. The results show higher mean scores in Oxford grading for LG1 compared to LG2. These results might prove weak performance of LG2 in staining of ocular surface. Also, LG2 didn’t show LWE and Marx line in any of the photos, whereas LG1 showed LWE and Marx line in a significant number of photos. Due to no LWE and absence of Marx line in all cases related to LG2, it seems this brand is unable to be the proper diagnostic dye in detecting eye structures’ changes, especially lid margin changes. Conclusion There was significant difference in performance between two brands of LG in Oxford staining, LWE and Marx line showing up. There was no difference in reporting burning sensation between the two LG brands.