Factors responsible for tear ferning

The biochemical agents involved in fern formation on drying tears were investigated by studying the different patterns of ferning of tears from normal and pathological eyes, mucus glycoprotein, saliva, serum, and various salt solutions. We conclude that the ferning phenomenon observed when a drop of tears is allowed to dry at room temperature on a clean microscope slide is to a large extent determined by the electrolyte concentration, especially the ratio of monovalent sodium and potassium ions to divalent calcium and magnesium ions. The presence of a biopolymer is essential, but this need not specifically be mucus as previously thought. The test may therefore be useful clinically in indicating the need for further tear analysis.     

The basis of tear ferning

Fern-like crystallisation occurs in many body fluids when sampled and dried, including the tears. Tear ferning has been proposed as a diagnostic test of keratoconjunctivitis sicca (KCS), but the mechanism of reduced ferning in the dry eye is poorly understood. By microscopic examination of tear ferns and review of gynaecological and crystallographic literature, we seek an explanation for the reduced tear ferning in KCS. The physico-chemical variables controlling the crystal ‘habit’ (viscosity, osmolality, protein content, and mucous quality or quantity) are examined to ascertain which might be responsible for the decreased ferning of dry eye tear samples. We hypothesise that a shift in the salt-to-macromolecule ratio, increased lipid contamination of mucus and altered tear rheology are the features of dry eye which best explain the altered ferning patterns in this condition.     

Tear mucus ferning in patients with Sjögren's syndrome

The purpose of this study is to evaluate the possibility of using the mucus ferning phenomenon of the tears as a diagnostic test for Keratoconjunctivitis sicca in patients with Sjögren's syndrome. Using a polarising light microscope dried samples were tested for ferning phenomenon collected from (1) 36 healthy controls, (2) 21 patients with primary Sjögren's syndrome, and (3) 15 patients with secondary Sjögren's syndrome. Patients with Sjögren's had xerostomia, abnormal salivary gland biopsy and at least two positive tests for Keratoconjunctivitis sicca. Patterns of mucus crystallization were classified into 5 types according to uniformity, branch spreading and integrity (types I, II normal, types III, IV, V abnormal). Abnormal ferning was found in tear samples of 8 out of 72 normal control eyes, 38 out of 42 with primary Sjögren's syndrome and 25 out of 30 with secondary Sjögren's syndrome. The differences between both primary and secondary Sjögren's syndrome, in comparison to healthy controls, were significant (p<0.001). The sensitivity of the method was found 90% for primary Sjögren's syndrome and 80% for secondary Sjögren's syndrome. According to our data, tear mucus ferning test is a simple, sensitive and specific test to estimate Keratoconjunctivitis sicca in patients with Sjögren's syndrome.     

Tear ferning and other lacrimal tests in normal persons of different ages

Summary We investigated in normal persons of different ages ranging from 4 months to 85 years the frequency of different ferning types as well as the results of the Schirmer I test, break-up time and tear protein profile. With increasing age, ferning types of higher degree were significantly more frequent. Furthermore, a correlation was found between the ferning test and low Schirmer test values (p < 0.05) as well as break-up time (p < 0.1). No correlation exists between ferning the test and tear protein pattern. These results indicate that tear ferning is independent from single tear proteins but in correlation with secreted watery volume and plays some role in tear film stability. Furthermore, these normal values of ferning and protein pattern can be used as references for different ages.     

The role of apoptosis in induction ocular changes in patients with cystic fibrosis

PURPOSE: To evaluate the concentration of sFas in tear film of cystic fibrosis patients. MATERIAL AND METHODS: Tear samples were collected from 20 patients with cystic fibrosis and 20 patients from control group. The sFas levels were determined by immunoenzymatic assay ELISA. RESULTS: We found statistically increased levels of sFas in tear film of patients with cystic fibrosis compared with control group. CONCLUSIONS: Apoptosis may play role in the pathogenesis of ocular changes in cystic fibrosis patients. The above results are important for the choice of the treatment of dry eye syndrome in patients with cystic fibrosis.     

Ocular Ferning Test: A Qualitative Test for Mucus Deficiency

A new qualitative test for the study of conjunctival mucus has been developed. Conjunctival scrapings were obtained from 196 patients. Microscopic mucus ferning (arborization) was observed in 148 (91%) patients with various forms of acute conjunctivitis. Six patients (18%) with cicatrizing conjunctivitis (diffuse conjunctival cicatrization, ocular pemphigoid, Stevens-Johnson syndrome) had mucus ferning in their conjunctival scrapings specimens. Mucus ferning was significantly absent (P < 0.005) in patients with diffuse conjunctival cicatrization when compared to mucus ferning in other forms of conjunctivitis. Ocular mucus ferning test is a simple inexpensive office test for the evaluation of patients with mucus deficiency.     

Ocular ferning during the menstrual cycle in healthy women

PURPOSE: The aim of the study is to investigate whether tear ferning patterns change during different phases of the menstrual cycle. METHODS: The tear ferning test was performed on twelve normal women of childbearing age at three day intervals throughout one complete menstrual cycle. Serum hormone levels (progesterone, estrogen, testosterone) were measured. RESULTS: Eight women showed type I ferning, and the other four had type II ferning initially. These patterns did not change during the menstrual cycle. Serum hormone levels were all in the normal range. Since no change in ferning pattern was detected during the menstrual cycle, the ferning test can be done at any time in women. CONCLUSIONS: This study showed no effect of different menstrual cycle phases on tear ferning patterns.     

Ferning test in Down's syndrome.

The tear film was evaluated by the ferning test. We tested tear film in right and left eye on 28 subjects (total 56 eyes), of whom 14 were affected by Down's syndrome, age range 18 to 35 years. The results obtained show that there exists an alteration of the tear ferning in subjects affected by Down's syndrome. We did not find any difference between the right or left eye in each individual. This anomaly could be responsible for frequent infectious pathologies found in the anterior eye segment in these subjects.     

Ocular Ferning test - effect of temperature and humidity on tear Ferning patterns

BACKGROUND: The ocular ferning test is used as a diagnostic aid to evaluate patients with dry-eye disease. The ferning phenomenon is a dendritic growth form of dried tear fluid. The influence of temperature and relative humidity (rH) on the morphology of tear ferning patterns was investigated. METHODS: Two microliters of tear fluid of 5 volunteers with normal tear function were dropped onto a microscope slide with a pipette and were dried in a climatic chamber at four different temperatures (20, 22, 24 and 26 degrees C) and at four different grades of rH (30, 40, 50 and 60%) at each temperature. The dried droplet was divided according to distinct morphological features into a center, transition zone and margin. The center of the dried droplet was classified into four types according to the system of Rolando. RESULTS: In the temperature range between 20 and 26 degrees C, rH has a strong influence on the ferning patterns. At these temperatures, increasing rH resulted in a deterioration of type I ferning obtained at 30% rH to type II or type III at 60% rH in all subjects. Otherwise, at rH of 30, 40 and 50%, no definite influence of temperature between 20 and 26 degrees C was observed. At an rH of 60%, the ferning patterns changed with increasing temperature from 20 to 26 degrees C from type II to type III. CONCLUSION: High humidity can modify and deteriorate the ferning patterns of tear fluid from subjects with normal tear function. To obtain reproducible results using the ocular ferning test, stable conditions are necessary. An rH not higher than 50% at a temperature range between 20 and 26 degrees C produced ferning patterns without interstitial spaces which could be related to the best quality according to the system of Rolando.     

Ocular surface alteration after long-term treatment with an antiglaucomatous drug.

BACKGROUND: This study was undertaken to see whether long-term locally applied ocular medications produced any alterations in the ocular surface, and, in particular, whether it caused damage to the mucus layer of the tear film. METHODS: The authors studied the ocular surface of 40 control subjects (group 1), 21 patients (group 2) chronically treated with a commercial preparation of 0.5% timolol maleate, and 20 previously untreated glaucomatous patients (group 3) in need of treatment with the same drug. Parameters studied were Schirmer's test, lacrimal meniscus height, break-up time, fluorescein and rose Bengal stains, conjunctival impression cytology, mucus staining, and the ferning test. RESULTS: Patients in groups 2 and 3 showed a significant decrease (P less than 0.001) in the number of normal Schirmer's and break-up time tests. All had positive vital stains. Results showed a significant decrease (P less than 0.001) in goblet-cell density, mucus granules, and reticular sheets, and an increase (P less than 0.001) in pathologic crystallization patterns. CONCLUSION: These results demonstrate that chronic application of a commercial preparation of timolol maleate damaged the ocular surface, especially the mucus layer of the tear film.     

Tear osmolality and ferning patterns in postmenopausal women.

PURPOSE: To compare tear osmolality and ferning patterns in postmenopausal women (PMW) with and without dry eye symptoms. METHODS: Thirty-seven healthy PMW (>50 years of age), not on hormone replacement therapy, were categorized as being symptomatic or asymptomatic of dry eye based on their responses to an Allergan "Single-Item Score Dry Eye Questionnaire" (SIDEQ). They subsequently completed the Allergan "Ocular Surface Disease Index" (OSDI) questionnaire. Tear samples were collected from participants to evaluate osmolality and ferning patterns. A novel freezing point depression osmometer (Advanced Instruments Inc., Model 3100 Tear Osmometer), was used to measure the osmolality of the tear film. The tear ferning test was performed and evaluated for the quality of ferning based on the Rolando grading system. RESULTS: SIDEQ responses revealed 21 symptomatic and 16 asymptomatic participants. The OSDI total score was 6.5 +/- 5.9 for the non-dry-eyed (NDE) group and 25.7 +/- 12.4 for the dry-eyed (DE) group. The subscores for the DE group were significantly greater than the NDE group (p < 0.001). Osmolality values in DE individuals were significantly different from NDE (328.1 +/- 20.8 vs. 315.1 +/- 11.3 mOsm/kg; p = 0.02). Fifty percent of the DE participants showed type II ferning patterns and 29% of the DE participants showed type III ferning patterns, whereas the NDE participants showed either type I (44%) or II (66%) ferning patterns. There was a significant difference between the DE and NDE participants for the ferning patterns (p = 0.019). There was no significant correlation between tear osmolality and tear ferning (DE: r = 0.12; p > 0.05, NDE: r = -0.17; p > 0.05). CONCLUSIONS: Osmolality in mild and moderately DE PMW is higher than in NDE PMW and tear ferning is a rapid, simple, noninvasive laboratory procedure that indicates altered tear quality in PMW with symptoms of dry eye.     

Tear functions in patients with pinguecula

PURPOSE: To investigate the tear flow, tear film stability and condition of mucus in patients with pinguecula. METHODS: The Schirmer I and ferning tests were performed and break-up time (BUT) was determined in 57 patients with pinguecula [random eyes; 34 males and 23 females, 18 to 70 years of age (mean +/- SD: 39.1 +/- 13.5 years)] and in 57 age-matched subjects (control) [random eyes; 35 males and 22 females, 11 to 70 years of age (mean +/- SD: 37.8 +/- 15.2 years)], and the test results were statistically analysed. RESULTS: The mean Schirmer test value was 22.72 +/- 12 mm in the eyes with pinguecula and 22.7 +/- 8.5 mm in the control eyes. There was no statistically significant difference (t = 0.01, p = 0.99) between the groups. The mean BUTs were 11.42 +/- 6.89 s in the eyes with pinguecula and 15.46+/-5.85 s in the control eyes. Comparison of BUTs between the groups revealed a statistically significant difference (t = 3.37, p = 0.0010). Also, ferning types were found to be significantly abnormal in the eyes with pinguecula (p < 0.01). CONCLUSION: The alteration in the mucin layer is a possible change inducing pinguecula formation, or it may reflect an already existing pathology in the cells on the ocular surface.     

The tear ferning test: a simple clinical technique to evaluate the ocular tear film

A healthy tear film is very important for many major functions of the ocular surface. Dry eye disease is a significant clinical problem that needs to be solved but the poor correlation between clinical signs and reported symptoms makes it difficult for the clinician to apply a scientific basis to his clinical management. The problem is compounded by the difficulties of evaluating the tear film due to its transparency, small volume and complex composition. Practical insight into tear film composition would be very useful to the clinician for patient diagnosis and treatment but detailed analysis is restricted to expensive, laboratory‐based systems. There is a pressing need for a simple test. The tear ferning test is a laboratory test but it has the potential to be applied in the clinic setting to investigate the tear film in a simple way. Drying a small sample of tear fluid onto a clean, glass microscope slide produces a characteristic crystallisation pattern, described as a ‘tear fern’. This test is currently not widely used because of some limitations that need to be overcome but several studies have demonstrated its potential. Such limitations need to be resolved so that tear ferning could be used in the clinic setting to assess the tear film.     

Relationship of impression cytology and tear ferning to reports of dry eye.

PURPOSE: This study investigated whether there is a significant correlation between mild-to-moderate patient reports of dry eye and results on the tear ferning and impression cytology tests. METHODS: One hundred and four subjects were surveyed for presence or absence of dry eye symptoms. Membrane impression cytology and tear ferning were performed on each subject. Impression cytology specimens were evaluated for the presence of goblet cells, presence of epithelial cell sheets, and epithelial cell morphology. Tear specimens were evaluated for quality of ferning. RESULTS: A significant correlation was found between subjective dry eye symptoms and impression cytology results (cc = 0.28, p = 0.003). However, there was no statistically significant correlation between dry eye symptoms and tear fern results (cc = 0.072, p = 0.458). CONCLUSIONS: Impression cytology appeared to be a better predictor of mild-to-moderate dry eye symptoms than tear ferning.     

An interesting use of the study of tear ferning patterns in contactology

A study of tear ferning patterns in normal and keratoconjunctivitis sicca eyes led to the classification into 4 types by Rolando [1984]. We practised this in our laboratory and observed specific and distinct tear ferning patterns for electrophoretic types 1 and 2 which Liotet et al. [1983] described as abnormal tear proteins modification found in patients who repeatedly and rapidly clog their hydrophilic lenses. In a general way, a study of tear ferning patterns can result in an appreciation of tear quality in contactology.     

The eye in cystic fibrosis

PURPOSE: To investigate modifications of ocular surface and lens transparency in patients with cystic fibrosis in relation to the stage of digestive insufficiency. METHODS: Forty consecutive patients with cystic fibrosis and 24 age- and sex-matched healthy volunteers were examined. The tear tests (Schirmer's basic test, tear film break-up time) and conjunctival exfoliative cytology (CC) were used to study the ocular surface. The lens transparency was measured with the Opacity Lens Meter 701 (OLM 701, Interzeag AG, Switzerland). Digestive insufficiency was evaluated by the steatocrit method. RESULTS: Significant changes in conjunctival cytology and lens opacity, and abnormal tear tests were detected in CF patients; the alterations were more pronounced in patients with severe digestive insufficiency. CONCLUSIONS: Cystic fibrosis patients present ocular surface abnormalities and lens transparency modifications and their severity is related to the digestive insufficiency. Simple, rapid and non-invasive tear tests and cytological procedures might be used as additional tests for assessing the severity of cystic fibrosis.     

The ocular surface in cystic fibrosis

Seventeen patients with cystic fibrosis and 17 age-, race-, and sex-matched controls were examined under standardized conditions. Testing included slit-lamp biomicroscopy, fluorescein staining, rose bengal staining, Schirmer's basic tear test, tear film break-up time, tear pH, tear lysozyme, tear protein, lid and conjunctival cultures, and conjunctival impression cytology. Cystic fibrosis patients showed a statistically significant increase in the incidence of fluorescein staining and clinical blepharitis, as well as significantly decreased Schirmer testing and tear lysozyme. Ocular surface abnormalities in these patients may be attributable to aqueous and lipid tear film deficiencies. Cystic fibrosis patients showed normal conjunctival epithelial cell morphology, grew no pathogenic organisms, and had a decreased incidence of conjunctival bacterial colonization.     

Forecasting of hydrophilic contact lens tolerance by means of tear ferning test

· Background: The ability of the tear ferning test to predict future hydrophilic contact lens tolerance was studied. · Methods: The tear ferning test (TFT) was performed on one randomly chosen eye of each of the 116 subjects who came to our contact lens clinic for hydrophilic contact lens application. The TFT was performed at the time of enrollment (T0) and then 1 month (T1), 3 months (T2) and 6 months (T3) after contact lens fitting. The specificity and the sensitivity of the TFT in identifying future contact lens tolerance was then studied. The statistical significance of the differences in behavior through the study period among the subjects with different pre-fitting TFT results was evaluated by means of survival curves. · Results: When only type I ferning was considered as a marker of good tear film conditions, the ability of the TFT to forecast contact lens tolerance had 78.95% sensitivity, 78.35% specificity and 78.45% diagnostic precision. The TFT showed sensitivity of 100%, specificity of 86.6% and diagnostic precision of 97.4% when performed after 1 month of contact lens wearing (T1). Survival curve analysis showed a statistically significant difference in behavior between the group of subjects with pre-fitting ferning type I and the other three groups (P<0.001). · Conclusion: The TFT appears to have good sensitivity and specific for prediction of contact lens tolerance in a clinical setting. Received: 2 May 1997 Revised version received: 28 July 1997 Accepted: 9 September 1997     

Measurement of acute response to draught in the eye

In order to assess the sensitivity to draught of 7 different tests, 41 volunteer subjects were exposed experimentally: 18 to 1.0 m/s and 9 to 0.5 m/s in a climate chamber: 14 to an average of 0.67 m/s in an air-conditioned car. All exposures were at 21-22 degrees C. Exposures were for 30 min indoors, 45 min in the car. Break-up Time (BUT) of the pre-corneal film after a blink was observed before and after exposure in the laboratory. There was a significant decrease after exposure to 1.0 m/s (P less than 0.01) but not to 0.5 m/s. The variance of the observed BUT increased after exposure to 0.5 m/s (P less than 0.05). The Norn Lacrimal Dilution test showed increased tear flow after the climate-chamber exposures (P less than 0.05). Self-reported BUT(S) was always several times longer than BUT. There was a significant correlation between these measures (P less than 0.05) before exposure, but not after. BUT(S), like BUT, decreased after exposure to 1.0 m/s (P less than 0.01), but not after 0.05 m/s. However, the variance of BUT(S) did not increase significantly after 0.5 m/s; it decreased significantly after 1.0 m/s (P less than 0.01). A significantly improved mucus ferning pattern was observed after draught exposure (P less than 0.005), presumably due in part to increased lacrimal flow. There was no significant effect of draught on the albumin content of tear samples taken before and after exposure. Lissamine Green staining performed before and after exposure revealed no effect on micro-damage to the conjunctival epithelium.     

Quantitative tear ferning. Methodologic and experimental investigations

The reproducibility of different tear-ferning methods has been investigated by double tests on 122 subjects. Rough grading according to Rolando gives identical recovery in only 42 to 50%. Quantitative test (mm2 ferning per 1 microliter) of conjunctival fluid drawn with a glass rod according to Rolando gave a coefficient of variation of 99 to 128%. Aspiration with a quantitative pipette acc. to Norn 79%, and 55% for a standardized dilution (2.5 microliters of water) in the same pipette. The coefficient of variation was lower between tear samples aspirated through a thin capillary tube (1 mm = 0.5 microliter) from the lateral part of the tear meniscus (35%), and with a standardized tear volume (2.5 microliters) only 6.4%. Ferning is obstructed by ointment, fat emulsion dropped on the conjunctiva and mucous thread, but not by a glass slide rubber with stearin. A quantitative test with a capillary tube (2.5 microliters of aspirated lacrimal fluid) showed reduced ferning 30 sec after instillation of methylcellulose (2.5%) and arachis oil, and after expression of meibomian gland secretion. No significant alteration was observed after instillation of water or stimulation of the tear secretion by nasal inhalation of NH4OH.