Dr. Pankaj Choudhary, C08132, Dr. Priyanka Agnihotri
INTRODUCTION :
The superficial lipid layer of tear film is thin and oily,[1] around 0.1 μm thick[2] and is derived mainly from the tubuloacinarmeibomian glands in the upper and lower eyelids.[3]Meibomian gland dysfunction (MGD) is a chronic disease usually caused by obstruction of the secretory meibomian glands. The subsequent reduction of gland secretion results in a decreased amount of lipids in the tear film which causes faster evaporation of the tear film thus resulting in an evaporative dry eye.MGD alone is responsible for about 60% of all cases and in combination with aqueous deficiency for a further 20% of dry eyes.
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’. Tabbara and Okumoto(4) as well as Rolando(5) proposed the use of tear ferning patterns to evaluate tear quality. Specific ferning pattern is due to an interaction between various electrolytes in the tears and macromolecules such as proteins.(6) An increased salt concentration in tears and other changes in tear composition may cause an alteration in the ferning patterns observed. (7)
AIM: To evaluate the role of tear ferning test inMeibomian gland dysfunction.
METHODology: 40 eyes of 40 patients of age 20-55 years withMeibomian gland dysfunction were included in this prospective nonrandomized observational study of one year duration in department of Ophthalmology at tertiary centre in central India. All subjects had a comprehensive eye examination, which included slit lamp assessment to establish baseline anterior segment health and determine participant eligibility. Informed consent was obtained from all subjects after the procedures were explained. The examination started by evaluating the tear film by usingSchirmer tear test I, Tear film breakup time and tear ferningtest,for tear ferning test about 1 μl of unstimulated tears were collected from the lower meniscus of the subject’s right eye using a capillary tube when the subject was seated with the head resting comfortably. The sample was then dropped onto a precleaned microscope slide and allowed to air dry for 10 min. The samples were observed using a light microscope and the photographs of each sample were taken immediately to avoid any changes in the ferning pattern. Rolando’s tear ferningclassification (5) was used to categorise the ferning pattern.
RESULTS:The maximum numbers of patients were found in the age group 40-50 years which is 37.5%% of the cases. The mean TBUT was± 7.1 sec. The meanSchirmer tear test score was13.4 ± 7.32mm. Abnormal fern pattern type III was observed in 9 (11.25%) eyes and type IV in 6(7.5%)with Meibomian gland dysfunction..
Discussion-
Clinical signs and symptoms of dry eye are poorly correlated makes its management difficult in Meibomian gland dysfunction.Rolando(5) identified dissimilarity among tear ferning patterns and presented a classification system, which has become a useful diagnostic tool in tear ferning studies. It has been classified into four qualitative categories, which are based on the size, the appearance and density of the ferns observed. Rolando noted that normal tear film often showed a type I pattern (with lots of ferns and tightly packed together) or type II pattern (abundant ferning but with spaces in between them), whereas type III (reveals scarce or single ferns) and type IV (absence of ferns) demonstrated poor tear ferningpatterns. Tearferning is relatively uncommon test but is a useful and comparable test to diagnose dry eye. Studies conducted by Rolando (5) and Kogbe et al (8) found that more than 80% of normal eyes showed type I and type II patterns and in keratoconjunctivitissicca patients, more than 90% had type III and type IV ferningpatterns. In our study Abnormal fern pattern (type III and IV) were observed in 15 (18.75%) eyesof patients with meibomeian gland dysfunction.Tear ferning patterns have been investigated in association with overnight variation,(9) post-menopausal women(10) after pterygium excision(11) and in contact lens wearers(12) These studies have shown that ferning patterns were worse upon waking, dry eye sufferers amongst post-menopausal women and in CL wearers. All these studies proved that tear ferning test is useful in assessing the pre-ocular tear film and dry eye. Limitation to study is small sample size so further study is required and this test is currently not widely used because of some limitations that need to be overcome so that tear ferning could be used in the clinic setting to assess the tear film.
CONCLUSIONS: As pattern of ferning depends on the composition of the tear soferning test is easy and cost effective simple test for tear film quality at a gross biochemical level and can be used in Meibomian gland dysfunction. A combination of the tear ferning test with other tear film tests in the clinic may then provide a real evaluation of the tear film and dry eye and may help in the treatment of dry eye
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href=”https://www.ncbi.nlm.nih.gov/pubmed/19236590″>PubMed]
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