The Effect of the Addition of Electrolyte Solutions on the Ferning Patterns of Tears Collected from Normal Eye Subjects

Abstract

SIGNIFICANCEThe current study is the first report to describe the improvement of ferning patterns of human tears using electrolyte solutions. The results can help in the production of new artificial tears to improve the quality of tears.PURPOSEThis study aimed to investigate the effect of the addition of different volumes of various electrolyte solutions on ferning patterns of human tears.METHODSTear samples (20 μL) were collected from the right eye of 13 subjects (5 men and 5 women) aged 19 to 36 years (27.1 ± 5.1 years) with normal eyes. Then, 1 μL of each tear sample was dried on a microscopic glass slide, and obtained ferns were observed using light microscopy and graded using the 5-point tear ferning (TF) grading scale. Homogenous mixtures of each tear sample (0.5 μL) and different volumes (0.5 to 5 μL) of each electrolyte were prepared. A sample (1 μL) of each mixture was dried, and the ferns obtained were graded and compared with those of the corresponding tears collected from subjects before the addition of electrolyte solutions.RESULTSAfter the addition of electrolyte solutions, the TF grades of tears collected from healthy humans were generally improved. Significant (Wilcoxon test) improvements have been seen in the TF grades of the tear samples after the addition of a solution of potassium chloride (P = .03), calcium chloride (P = .01), magnesium chloride hexahydrate (P = .002), and sodium dihydrogen phosphate (P = .002). No significant improvements in the TF grades were seen after the addition of sodium chloride solution (P = .33).CONCLUSIONSFerning grades of human tears improved with most of the electrolytes used.

Effect of monovalent electrolyte solutions on the human tear ferning pattern

“…The dilution effect on the TF patterns of tears was tested in which different proportions of water were added to the tear samples (1:1 to 1:5). No changes were noticed in the TF grades of tears after the addition of water, which is consistent with a previous report [27]. Two masked examiners graded the TF patterns.…”

“…It has been reported that the TF grades of tears collected from humans and animals and eye drops improved after the addition of electrolyte solutions [25][26][27]. Generally, divalent electrolytes lead to greater improvement in TF grades compared with monovalent ones [25][26][27].…”

“…It has been reported that the TF grades of tears collected from humans and animals and eye drops improved after the addition of electrolyte solutions [25][26][27]. Generally, divalent electrolytes lead to greater improvement in TF grades compared with monovalent ones [25][26][27]. However, no improvements were observed in the TF grades of the tears collected from sheep after the addition of solutions containing a large quantity (680 mg in 100 mL of water) of NaCl [25].…”

“…However, various limitations have been associated with these reports, such as low sample size, lack of statistical analysis, and limited or no improvements in TF grades after the addition of NaCl and KCl solutions. Therefore, the current study was conducted to overcome some of the limitations associated with the previous related report [27]. We report an improvement in TF grades of tears collected from humans after the addition of a low concentration of NaCl and KCl solutions.…”

“…In recent years, the effect of the addition of electrolyte solutions on the TF patterns of human, animal, and artificial tears was investigated [24][25][26][27]. However, various limitations have been associated with these reports, such as low sample size, lack of statistical analysis, and limited or no improvements in TF grades after the addition of NaCl and KCl solutions.…”