Improvement of ferning patterns of lubricant eye drops mixed with various electrolytes and carboxymethylcellulose

Abstract

PurposeTo investigate the effect of the addition of electrolytes, basic tear solution (BTS), and sodium carboxymethylcellulose (SCMS) on the tear ferning (TF) patterns of Blink Contact Soothing Eye Drops® and Refresh Plus Tears®. MethodSamples of Blink Contact Soothing Eye Drops® and Refresh Plus Tears® (10 μL) were mixed with different volumes (3–30 μL) of several electrolytes, namely sodium chloride, potassium chloride, calcium chloride, magnesium chloride hexahydrate, sodium hydrogen carbonate, and sodium dihydrogen phosphate, BTS, and SCMS. Samples (1 μL) of the mixtures were dried on a glass slide at room temperature and the TF patterns were inspected using a light microscope, graded using the Masmali five-point grading scale and compared to the corresponding TF grades of the artificial tears. ResultsThe TF grades of Blink Contact Soothing Eye Drops® and Refresh Plus Tears® improved from 1.2 and 1.5, respectively to 0.2 when calcium chloride was used as the electrolyte. Improvements in TF grades were also observed when other electrolytes (e.g., sodium dihydrogen phosphate), BTS, and SCMS were used. ConclusionThe tear ferning test can be used to evaluate the effect of the addition of electrolytes to an artificial tear in-vitro. The TF patterns of artificial tear solutions such as Blink Contact Soothing Eye Drops® and Refresh Plus Tears® can be improved with the addition of various concentrations of electrolytes, BTS, and SCMS, however further research is still needed to understand the clinical relevance of TF patterns with respect to the management of dry eye symptoms and their potential role in the development of new artificial tears.