Application of a new grading scale for tear ferning in non-dry eye and dry eye subjects.

PURPOSE: To apply the Masmali tear ferning (TF) grading scale on non-dry eye (NDE) and dry eye (DE) subjects to test the validity of the grading scale in practice, and to describe the grading scale range for NDE and DE.

METHOD: Forty NDE subjects (20 males, 20 females) and 40 DE subjects (23 males, 17 females) ranging in age from 19 to 53 years (mean±SD: 25.3±5.5) with no other ocular disease, no contact lens wear, and not pregnant or breastfeeding were recruited. McMonnies scores were used for subject grouping. Phenol red thread (PRT) and slit-lamp test were used. A tear sample was collected from right eye, which was then dried to produce a ferning pattern, that was observed using a digital microscope, and graded.

RESULTS: Mean McMonnies, PRT and TF grade in NDE subjects were 7.1±3.8, 27.4±4.3 mm and 0.78±0.40, respectively. Median McMonnies, PRT and TF grade in DE subjects were 16.5±3.0, 9.0±2.0 mm and 2.3±1.48, respectively. In NDE subjects, grades 0.0-1.8 were observed (82.5% Grade 0.0-1.00). Grades 2.0-4.0 were observed in DE subjects (72.5% Grades 2.0-3.0). For all subjects, there were large correlations between TF grade and PRT (r=-0.79), PRT and McMonnies (r=-0.60), and TF and McMonnies (r=0.73).

CONCLUSIONS: The Masmali TF grading scale showed good validity in describing the TF patterns. Grades ≥2 can be classified as abnormal patterns. The TF test has the potential to be used in the clinic.