Ali Masmali

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.

Development of a new grading scale for tear ferning

PURPOSE This paper reports on the development of a new tear ferning (TF) subjective grading scale, and compares it with the Rolando scale. METHOD TF patterns obtained from tear film samples collected from normal and dry eye subjects in previous studies were collated into a large image library. From this library, 60 images were selected to represent the full range of possible TF patterns, and a further sub-set of 15 images was chosen for analysis. Twenty-five optometrists were asked to rank the images in increasing order between extreme anchors on a scale of TF patterns. Interim statistical analysis of this ranking found 7 homogeneous sub-sets, where the image rankings overlapped for a group of images. A representative image (typically the mean) from each group was then adopted as the grade standard. Using this new 7-point grading scale, 25 optometrists were asked to grade the entire 60 image library at two sessions: once using the 4-point Rolando scale and once using the new 7-point scale, applying 0.25 grade unit interpolation. RESULTS Statistical analysis found that for the larger image set, the Rolando scale produced 3 homogeneous sub-sets, and the 7-point scale produced 5 homogeneous sub-sets. With this refinement, a new 5-point TF scale (Grades 0-4) was obtained. CONCLUSIONS The Rolando grading scale lacks discrimination between its Type I and II grades, reducing its reliability. The new 5-point grading scale is able to differentiate between TF patterns, and may provide additional support for the use of TF for both researcher and clinician.

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.

Comparative study of repeatability of phenol red thread test versus Schirmer test in normal adults in Saudi Arabia.

Objective: To investigate the repeatability of the phenol red thread (PRT) and Schirmer tests in healthy Saudi adults. Additionally, we compared the PRT mean value with those reported previously because of significant differences between Hong Kong-Chinese, Japanese, and US subjects. Methods: Thirty healthy young Saudi adults (7 men and 23 women; 60 eyes) with a mean age of 22.37±2.31 years were recruited. Participants provided consent and completed a McMonnies questionnaire. Dry eye subjects were excluded based on this questionnaire and slit-lamp examination. Both eyes of each subject were examined using the PRT and Schirmer tests. Each test was repeated three times for each eye, five minutes apart. The PRT test was applied first, followed by the Schirmer test 15 minutes later under anesthesia to avoid any inconsistency of the measurements due to reflex tears. Results: The PRT and Schirmer tests both demonstrated good repeatability with no statistically significant differences. There was a poor correlation between the 2 tests (r=0.286). There was no statistically significant difference between OD and OS in the two tests. The mean PRT values in normal Saudi subjects were higher than those reported previously for Hong Kong-Chinese, Japanese, and US subjects. Conclusions: Both the PRT and Schirmer tests displayed good repeatability; however, there was a poor correlation between the tests, as reported previously. The mean PRT value in normal Saudis was higher, when compared with those reported previously for other ethnic groups.

A computer-based image analysis for tear ferning featuring

The present work focuses on the development of a novel computer-based approach for tear ferning (TF) featuring. The original TF images of the recently developed five-point grading scale have been used to assign a grade for any TF image automatically. A vector characteristic (VC) representing each grade was built using the reference images. A weighted combination between features selected from textures analysis using gray level co-occurrence matrix (GLCM), power spectrum (PS) analysis and linear specificity of the image were used to build the VC of each grade. A total of 14 features from texture analysis were used. PS at different frequency points and number of line segments in each image were also used. Five features from GLCM have shown significant differences between the recently developed grading scale images which are: angular second moment at 0° and 45°, contrast, and correlation at 0° and 45° these five features were all included in the characteristic vector. Three specific power frequencies were used in the VC because of the discrimination power. Number of line segments was also chosen because of dissimilarities between images. A VC for each grade of TF reference images was constructed and was found to be significantly different from each others. This is a basic and fundamental step toward an automatic grading for computer-based diagnosis for dry eye.

Crystal structure of 2-tert-butyl-1,3-thia-zolo[4,5-b]pyridine.

The title compound, C10H12N2S, does not contain any strong hydrogen-bond donors but two long C—H⋯N contacts are observed in the crystal structure, with the most linear interaction linking molecules along [010]. The ellipsoids of the tert-butyl group indicate large librational motion.

Tear ferning test in healthy dogs

PURPOSE To evaluate and compare three tear sampling methods using two grading scales for administering the tear ferning test (TFT) to healthy dogs. METHODS In total, 90 dogs (180 eyes) were subjected to tear sampling using millimetered strips, reused after the Schirmer tear test (STT) (Schirmer group, SG). Then, the dogs were subdivided into three groups according to sampling approach: micropipette (MPG), microcapillary (MCG), and Schirmer sample 2 (S2G). The collected tears were dried on a clean microscope glass slide at room temperature and humidity. The ferning patterns were observed under a polarized light microscope and classified according to the Rolando and Masmali grading scales. RESULTS Although all three methods were feasible, the STT was easier to perform in clinical settings. Type I and Grade 1 were the most commonly observed (64.17% and 61.7%, respectively) regardless of collection method. There was no significant difference between the STT median values and the TFT classifications. CONCLUSIONS The TFT is appropriate for dogs and can be performed using the three suggested sampling methods, with a higher frequency of Type I and Grade 1. Thus, it is possible to use both grading scales in the classification of tear ferning in dogs.

Analysis of basal and reflex human tear osmolarity in normal subjects: assessment of tear osmolarity

Purpose: The aim of this study is to evaluate the difference between reflex and basal tear osmolarity among healthy normal subjects. Method: The right eyes of 20 healthy normal male subjects aged 20 to 40 years were recruited for this study. The inclusion criteria for the subjects were the Ocular Surface Disease Index questionnaire score of less than 12 and wetting length of the phenol red thread of more than 10 mm. Tear film osmolarity was assessed using TearLab osmometer. Basic tear osmolarity was measured normally without inducing any irritation to the eye. In order to stimulate reflex tear, subjects were asked to open their eye as long as they can till they feel ocular surface irritation (minimum 20 s). Results: The mean score on the Ocular Surface Disease Index questionnaire was 5.5 ± 3. The mean value obtained from the phenol red thread was 21 ± 4.5 mm. There were no statistically significant differences between the osmolarity readings of basal and reflex tear osmolarity (p > 0.05). The mean value was 308 ± 12 and 306 ± 9 mOsm/l for basic and reflex tear osmolarity, respectively. Conclusion: This study found that the osmolarity of the basal and reflex tears fell within the same range. The values found in this study are in agreement with published results for normal subjects.

Evaluation of lacrimal production, osmolarity, crystallization, proteomic profile, and biochemistry of capuchin monkeys’ tear film

To evaluate the composition and characteristics of capuchin monkey (CM) tear film.

Ocular dryness assessment in Saudi employees working indoors and outdoors

Objective To investigate dry eye disease in Saudi employees working in indoor and outdoor environments. Methods A single-center randomized controlled study was carried out in an optometry clinic, to assess the ocular dryness of 24 male employees (12 indoor and 12 outdoor employees, mean age 36.4±2.5 years). The Ocular Surface Disease Index questionnaire was used to assess ocular dryness. Tear film assessment was carried out using phenol red thread (PRT), tear film osmolarity test, and fluorescein tears breakup time (FTBUT) with slit-lamp biomicroscopy. Results Both indoor and outdoor employees showed mild-to-moderate ocular dryness. A significant difference (P=0.004) was found for the tear quality test (FTBUT) between the indoor (8.58±4.8) and outdoor (5.54±1.3) employees. However, no significant differences for the tear quantity tests (tear osmolarity and PRT) between the indoor and outdoor employees were observed. Conclusion Dry eye cases were detected in both groups. This might be due to the hot dry environment in Riyadh and the use of air conditioners commonly used indoors. A significant difference was observed for the tear film stability, which might be due to the effect of environment and/or visual display unit use.