Purpose:To investigate age- and sex-related differences in tear film parameters of normal Indian population and study interparametric relationships.MethodsHealthy subjects with no ocular disease (median ocular surface disease index = 0) were subjected to an automated evaluation of tear meniscus height (TMH), non-invasive tear breakup time (NIBUT) using Keratograph 5M (OCULUS GmbH, Wetzlar, Germany), and tear osmolarity using the TearLab Osmolarity System (TearLab Corporation, California, USA). A mixed-effects model with random intercepts at the patient level was used to evaluate the relationships between explanatory (age, gender, and tear osmolarity) and outcome variables (TMH and NIBUT).ResultsA total of 237 subjects (474 eyes; 150 males) were enrolled with a mean age of 40 ± 17 years (range, 10-78 years). The mean values (± standard deviation) of TMH, NIBUT, and tear osmolarity were 0.34 ± 0.07 mm, 10.95 ± 2.02 s and 289.0 ± 5.8 mOsm/L, respectively. Age had a significant positive relationship with TMH (p < 0.0001; 0.002 mm/year; r = 0.12), but there was no effect on NIBUT (p = 0.26) and tear osmolarity (p = 0.27). There were no sex-based differences in tear film parameters. Interparametric relationship revealed no significant association between TMH and NIBUT (p = 0.12) or tear osmolarity and TMH (p = 0.83) or tear osmolarity and NIBUT values (p = 0.48).ConclusionsIn a normal Indian population, TMH is weakly affected by age and is independent of sex, NIBUT, and tear osmolarity. Tear breakup time and osmolarity show no significant age- and sex-related variation.
Lacrimal and meibomian glands contribute to the aqueous and lipid components of tear film, respectively. Their evaluation remains central to diagnosing and managing dry eye disease (DED). The review discusses the differences and reliability of various diagnostic tests and commercially available devices used for DED diagnosis. Slit-lamp-based techniques are direct palpebral lobe and tear flow assessment, Schirmer test, meibum quality and expressibility, and evaluation of tear meniscus height. Non-invasive tear meniscus height (TMH), tear break-up time (TBUT), lipid layer thickness (LLT), and meibography are machine-based diagnostic tests. The structure–function correlation of the tear-producing glands gives more comprehensive details than either information alone. Many devices are available in the market, which make DED diagnosis an easy feat, but the tests should be interpreted keeping in mind the intra-observer and inter-observer repeatability. Also, the tear film displays a huge variability as per the environmental conditions and impact of blinking. Hence, the examiner should be well versed with the techniques and repeat the test two to three times to obtain an average reading, which is more reliable. The recommended sequence of tests for diagnosing DED is a dry eye questionnaire, TMH, LLT, NIBUT (FBUT if non-invasive test is unavailable but should be performed after osmolarity), tear osmolarity, meibography, and ocular surface staining. Invasive tests such as Schirmer should be performed after the non-invasive tear film diagnostic testing.
PurposeTo investigate the effects of lacrimal drainage obstructions on the lacrimal gland activity and if there exists a potential link between the two.MethodsDirect assessment of the lacrimal gland activity from the palpebral lobe was performed in consecutive patients diagnosed with unilateral primary acquired nasolacrimal duct obstruction (PANDO), along with Ocular Surface Disease Index (OSDI), non-invasive tear break up time (NIBUT; Oculus K5M), tear meniscus height and Schirmer I. The primary outcome measure was the difference in the tear flow rate between the eye with PANDO and the contralateral uninvolved eye.ResultsThirty patients (median age, 45.5 years; 25 females) with unilateral PANDO had epiphora for a mean duration of 20 months. The mean OSDI score was 6.3. NIBUT (mean 11.56 vs 11.58 s; p=0.49) and Schirmer I values (mean 18.83 vs 19.4 mm; p=0.313) were not significantly different between PANDO and non-PANDO eyes. The morphology of the palpebral lobe (size 29.3 vs 28.6 mm2, p=0.41) and the number of lacrimal ductular openings (median 2 vs 2.5) were similar between the two eyes. The mean tear flow from the lacrimal glands of the PANDO side was significantly reduced compared with the contralateral uninvolved side (0.8 vs 0.99 µL/min; p=0.014)).ConclusionTear flow rate from palpebral lobes of patients with unilateral lacrimal outflow obstruction shows a significant reduction compared with the contralateral side. The potential ways of communications between the tear drainage and the tear production mechanisms need to be explored further.
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