Finalist: Una Kelly
Project: Comparison of tear ferning and dry eye signs and symptoms prior to and following soft contact lens wear using various soft contact lens multipurpose solutions
Supervisor: Dr Veronica O’Dwyer
As explained by Una Kelly at the start of her presentation, ‘Tear ferning is the process of collecting a sample of a subject’s tear and observing the dried sample under a microscope, a fern like pattern is formed, as shown below, morphology of the pattern used to evaluate the tear film quality.’ The patterns are then graded from 0.5 to 3.0. Figure 1 shows a pattern graded as 0.5.
The aims of this ambitious project were to firstly use tear ferning to assess patients prior to contact lens insertion and then after a period of wear of lenses which had first been soaked in one of a range of multipurpose solutions (Optifree Pure Moist, Biotrue, Synergi and ReNu). In this way, it might be seen if tear ferning could be used to detect differences in MPS impact upon tears and also whether ferning compared with other methods of tear and dry eye symptom assessment.
The procedure was as follows;
1 Take tear sample from each eye, without stimulating reflex tearing. Allow tear to dry at room temperature and grade tear ferning.
2 OSDI questionnaire.
3 Grade dry eye signs.
4 Subject given three contact lens cases, each containing two lenses.
5 Subject to return after two to four hours of lens wear. Repeat steps one to three.
6 Two days later, repeat steps one to three with next pair of lenses, and two days subsequently with final pair.
As Kelly pointed out, ‘this double-blind procedure will prevent bias. Note each subject received unique instructions regarding which eye and in what order to wear the lenses. Ideally at the same time of day as Lens A and B were evaluated to minimise variation. Each lens was soaked in a different solution, including two lenses soaked only in saline.’
Results
‘Contact lens wear had an effect on all methods of dry eye observation utilised and these changes varied according to the multipurpose solution used – corneal staining, conjunctival staining, tear break up time (TBUT), tear meniscus height (TMH), OSDI questionnaire and tear ferning.’
Some key findings included;
- Biotrue solution created the greatest deviation from baseline in terms of tear ferning (2.25 ± 0.94) and corneal staining (0.83 ±1.29).
- The least variation in each of these factors was attributed to the saline solution: (1.67 ±0.70) and (0.16 ±0.25) respectively.
- Subjects showed the lowest TMH (0.19mm ±0.06) and TBUT after use of both saline and Specsavers/Synergi.
- Renu Fresh recorded the highest mean ODSI score (27.69 ±17.08) and Optifree the greatest conjunctival staining (1.50 ±0.83).
- Figure 2 summarises dry eye changes after different lens wear.
Figure 2: Ocular changes post contact lens wear
With regard to tear ferning, Kelly suggested the following conclusions. ‘Tear ferning was shown to correlate positively with all other objective methods of dry eye analysis, most strongly with corneal staining (0.89) and most weakly with TBUT (0.55). Tear ferning also showed a strong positive correlation with dry eye symptoms as measured by the OSDI questionnaire (0.80).
Conclusions
Norn (1994) showed that tear ferning deteriorated in patients with severe dry eye disease. This article reported sensitivity and specificity of tear ferning close to that of commonly used Schirmer 1 and TBUT.1 Tear ferning has been described as useful in diagnosis of dry eye disease, while having a weak relationship with tear film stability and subjective patient comfort.2 Results gleaned from this project support these prior writings on tear ferning’s relationship with dry eye signs, but found a stronger connection between tear ferning and dry eye symptoms than previously reported.
A well-structured study as all the judges agreed.
References
1 Norn, M (1994). Quantitative tear ferning. Acta ophthalmologica, 72(3), 369-72.
2 Evans, KS, North, RV, and Purslow, C (2009). Tear ferning in contact lens wearers. Ophthalmic and Physiological Optics, 29(2), 199-204.