Dry Eye Group Research Articles

Clinical signs and symptoms in post‐menopausal females with symptoms of dry eye

To characterize clinical signs and symptoms in a group of post-menopausal (PM) females who present with and without symptoms of dry eye. Eighty-three healthy PM females were categorized as being symptomatic or asymptomatic of dry eye based on their response to the Allergan Ocular Surface Disease Index (OSDI) questionnaire. Non-invasive tear breakup time (NITBUT) was evaluated using the ALCON Eyemap. Tear volume was assessed using the phenol red thread (PRT) test and bulbar conjunctival hyperaemia was measured using objective and subjective methods. The total OSDI score (TOS) and subscores for the non-dry eye (NDE; n = 39) and dry eye (DE; n = 44) groups were significantly different (TOS: NDE = 7.43 +/- 7.71 vs DE = 24.87 +/- 13.89; p < 0.001). The DE group exhibited a shorter NITBUT (5.3 +/- 1.7 s vs 7.0 +/- 2.7 s; p = 0.0012). Tear volume was lower for the DE group (19.3 +/- 5.1 mm vs 16.3 +/- 5.6 mm; p = 0.031). Bulbar hyperaemia was higher in the DE group for both subjective grading using a modified CCLRU scale (48.4 +/- 10.0 vs 40.6 +/- 10.4; p = 0.0011) and objective measurement by spectrophotometer (Commission Internationale de l'Eclairage u' value = 0.285 +/- 0.006 vs 0.282 +/- 0.006; p = 0.005). OSDI can be used to separate PM females who demonstrate clinical signs of ocular dryness. PM women with dry eye symptoms demonstrate shorter NITBUT, lower tear volume and increased bulbar conjunctival hyperaemia than those who have no symptoms.

MUC1 and estrogen receptor α gene polymorphisms in dry eye patients

Dry eye syndrome is a collection of common disorders of multifactorial etiology. Although the epidemiology of dry eye has been well studied, reports of genetic patterns that might influence susceptibility to dry eye are few. We reported that the frequency of non-Sjögren's aqueous-deficient dry eye patients expressing only the MUC1/A splice variant of the mucin MUC1 may be lower than that of a normal control group [Imbert, Y., Darling, D.S., Jumblatt, M.M., Foulks, G.N., Couzin, E.G., Steele, P.S., Young, W.W., Jr., 2006. MUC1 splice variants in human ocular surface tissues: possible differences between dry eye patients and normal controls. Exp. Eye Res. 83, 493–501]. Also, He et al. [He, Y., Li, X., Bao, Y., Sun, J., Liu, J., 2006. The correlation of polymorphism of estrogen receptor gene to dry eye syndrome in postmenopausal women. Yan. Ke. Xue. Bao. 22, 233–236] reported a difference between Chinese dry eye and control groups in the frequency of a polymorphism in estrogen receptor α (ERα). In the present study we determined the statistical significance and generality of these observations and tested if the MUC1 splice variant difference between subject groups reflected a difference in the MUC1 variable number of tandem repeat (VNTR) size class. There was a perfect correlation between the MUC1/A or MUC1/B splice variant pattern and the SNP genotype frequency of the SNP (rs4072037) controlling that splicing event. In contrast, western and Southern blotting indicated that MUC1 VNTR size class corresponded to the MUC1 SNP genotype in only 80% of cases. We determined the status of the MUC1 SNP in normal and dry eye populations all of whom were female Caucasians. The MUC1 SNP genotype frequency of the normal control group was statistically different from both the non-Sjögren's aqueous-deficient dry eye group with ocular surface staining (P=0.017) and the evaporative dry eye group (P=0.015). We also tested SNP rs2234693 to analyze the polymorphism in the ERα gene and found no significant difference in the SNP genotype frequency between the control group and either of the dry eye subtypes. Thus, among Caucasians there is no evidence for an association of the ERα gene polymorphism with dry eye syndrome as previously described in a Chinese population. In conclusion, the etiologies of evaporative dry eye and non-Sjögren's aqueous-deficient dry eye are known to be different. However, our results suggest that both of these subtypes of dry eye disease may share a common mechanism or factor related to MUC1 genotypic differences that affects susceptibility to ocular surface damage. This altered susceptibility may not be related to the MUC1 VNTR size class. Therefore, mechanisms influencing protection of the ocular surface against inflammation and damage in different types of dry eye disease warrant further investigation particularly in relation to MUC1 genotype.

Prevalence of dry eye among adult Chinese in the Beijing Eye Study

To study the prevalence and associations of dry eye symptoms in adult Chinese. The Beijing Eye Study is a population-based study in northern China, which included 4439 of 5324 subjects invited to participate with an age of 40+ years (response rate: 83.4%). For the present study, a random sample was taken consisting of 1957(44.1%) subjects (1112 women; 56.9%). Dry eye symptoms were evaluated with (1) an interviewer-assisted questionnaire; (2) measurement of the tear-film break-up time; (3) assessment of the fluorescein staining of the cornea; (4) slit-lamp-based examination of a meibomian gland dysfunction; and (5) Schirmer's test. Symptoms of a dry eye felt 'often' or 'at all times' were present in 411 subjects (21.0%). In a multivariate analysis, dry eye symptoms were significantly associated with age (P<0.001), female gender (P<0.001; odds ratio (OR): 1.56; 95% confidence intervals (CI): 1.23, 1.98), urban region (P<0.001;OR: 1.89; 95% CI: 1.46, 2.48), low degree of nuclear cataract (P=0.02), and undercorrection of refractive error (P=0.005; OR: 1.42; 95% CI: 1.11, 1.82). All tests for dry eye did not vary significantly between the dry eye group and the normal group. The dry eye symptoms as evaluated subjectively in a questionnaire occurred in about 21% of the adult population in China, with associations to age, female gender, urban region, and undercorrection of a refractive error. Measurement of the tear-film break-up time, assessment of the corneal fluorescein staining, slit-lamp-based examination of a meibomian gland dysfunction, and Schirmer's test were not significantly associated with dry eye symptoms.

Preoperative Characteristics and a Potential Mechanism of Chronic Dry Eye after LASIK

To determine whether measurable preoperative characteristics predispose patients to chronic dry eye after laser in situ keratomileusis (LASIK). The study consisted of 24 eyes of 24 patients who underwent LASIK. Tear breakup time, Schirmer testing with and without anesthesia, rose bengal staining, central corneal sensitivity, nucleus-to-cytoplasmic ratio, and goblet cell density were evaluated 2 weeks before and 1 week, 3 months, and 9 months after surgery. Patients were classified into two outcome groups, the nondry-eye group (NDEG) and the chronic dry-eye group (CDEG), on the basis of dry eye status 9 months after surgery. The authors tested whether preoperative values of each parameter were associated with the development of chronic dry eye. All parameters, except rose bengal staining, deteriorated significantly after surgery but returned to preoperative levels within 3 to 9 months. The CDEG had significantly lower preoperative Schirmer test values with and without anesthesia and were delayed in recovery after surgery in goblet cell density, rose bengal staining, Schirmer test values without anesthesia, and tear breakup time. Results of preoperative Schirmer tests without anesthesia positively correlated with tear breakup time 9 months after surgery. Preoperative tear volume may affect recovery of the ocular surface after LASIK and may increase the risk for chronic dry eye.

Keratoconjunctivitis Sicca Modifies Epithelial Stem Cell Proliferation Kinetics in Conjunctiva

The objective of this study was to examine the epithelial stem cell proliferation kinetics in a rat model with keratoconjunctivitis sicca (KCS). Wistar rats received a daily injection of 5-bromo-2-deoxyuridine (BrdU) at a dose of 5 mg/100 g of body weight for 2 weeks. Dry eye was induced in 2 groups of rats by subcutaneous injection of scopolamine and placed in a desiccating environment: The first group received dry eye treatment at the beginning of BrdU labeling for 2 weeks; the second group received dry eye treatment after BrdU labeling for 4 weeks. Rats receiving no dry eye treatment were used as controls. Aqueous tear production, tear clearance, and corneal barrier function of dry eye rats were compared with those of control rats. Ocular epithelial morphology and goblet cell density were also evaluated in histologic sections. One month after BrdU injection, epithelial stem cell proliferation kinetics was assessed by BrdU labeling. Significant decreases in tear fluid secretion and tear clearance were noted in rats 5 days after dry eye treatment, with significantly increased corneal carboxy fluorescein uptake. Changes in ocular surface epithelial morphology and significantly reduced density of conjunctival goblet cells were found in dry eye groups. The number of conjunctival BrdU label-retaining cells in the rats with dry eye was significantly decreased compared with control rats (P < 0.01 for both groups). Furthermore, BrdU labeling in the before dry eye induction group showed more label-retaining basal cells in the conjunctiva than labeling in the dry eye state group (P < 0.01). Experimentally induced KCS in rats causes significant modification of epithelial stem cell proliferation kinetics in conjunctiva. The modification of epithelial stem cell proliferation kinetics in conjunctiva may play a crucial role in the development of KCS and may be a therapeutic target for this condition.

Involvement of Oxidative Stress on Corneal Epithelial Alterations in a Blink-Suppressed Dry Eye

To investigate whether oxidative stress is involved in the etiology of the corneal disorder in blink-suppressed dry eye in a clinically relevant in vivo rat model. A series of treatments were performed under continuous exposure to low-humidity airflow. Rats were placed on a jogging board (JB) made of a plastic pipe for 7.5 h/d, and for 16.5 hours, they were placed in individual cages without a JB. This protocol was repeated for up to 30 days. Corneal surface alteration was evaluated by the score of punctate fluorescein staining. To assess oxidative stress status, the levels of damaged DNA, and the protein modification by reactive aldehydes in corneal epithelia were detected by immunohistochemistry, using 8-hydroxy-2-deoxyguanosine, 4-hydroxynonenal- and malondialdehyde-specific antibodies. Significant increases in the fluorescein staining score were observed from days 1 to 30 compared with the initial value. The average score for the dry eye group was significantly increased compared with that for the nontreatment group at all time points throughout the experiment. Immunoreactivity of all oxidative stress markers increased in the dry eye treatment. Quantitative analysis of the positive-stained cells showed a significant increase in the number of positive cells after 10 and 30 days in the dry eye treatment group compared with the nontreatment group. These results suggest a relationship between the accumulation of oxidative stress and the etiology of corneal epithelial alterations in blink-suppressed dry eye.

Tear Film Normalization Test

To evaluate the normalization of the tear film (tear film normalization test [TNT]) as a diagnostic test for dry eye syndrome. The uncorrected distance vision of 20 patients with dry eyes (40 eyes) and 20 normals (40 eyes) before and after instillation of carboxymethyl cellulose 0.5% (CMC; Refresh Plus; Allergan, Irvine, CA) was recorded. We used study early treatment diabetic retinopathy (ETDRS) vision charts to test vision in each eye. Tear film breakup time (TBUT), presence or absence of superficial punctate erosions (SPE), tear film meniscus height, meibomian gland function, and ocular surface disease index (OSDI) questionnaire scores were evaluated. CMC improved visual acuity in the dry eye group (P < 0.0001). Response operator's curve (ROC) analysis showed that vision improvement of 2 lines or more after tear normalization was associated with an 82.5% (95% CI: 66.6%-92.1%) sensitivity and 100% (95% CI: 89.1%-100%) specificity for dry eye. There was a significant correlation between vision improvement and OSDI score in the dry eye group (P = 0.003). The TNT is a highly sensitive and specific test for dry eyes and is available in every eye care professional's office. The more symptomatic the dry eye, the greater the improvement.

The Effects of Artificial Tear Application on Contrast Sensitivity in Dry and Normal Eyes

Purpose To investigate the effects of artificial tear application on contrast sensitivity in dry and normal eyes. Methods A total of 55 patients with normal (10/10) corrected or uncorrected visual acuity referring to GATA Gulhane Military Medical Academy Haydarpasa Ophthalmology Outpatient Clinic were evaluated in regard to dry eye diagnostic criteria, and assigned into the dry eye group (Group 1; 35 patients) and the control group (Group 2; 20 patients). All patients were given a contrast sensitivity testing at low and high spatial frequencies using the gradual contrast sensitivity chart before and at 5 minutes after application of artificial tears, and the two groups were compared. Wilcoxon test was used in statistical analysis, accepting a p value of &lt;0.05 as significant. Results In the dry eye group, there was a statistically significant increase in contrast sensitivity scores both at low and high frequencies after application of artificial tears (p&lt;0.05). In the control group, although there was a significant increase in low frequency scores after artificial tear application (p&lt; 0.05), there was not a significant change in high frequency scores (p&gt;0.05). Conclusions The decreased contrast sensitivity in dry eyes improves with application of artificial tears. Therefore, the impeded quality of vision seen in dry eye patients could be restored closer to normal with artificial tear therapy. Besides, contrast sensitivity testing could be used in the follow-up of artificial tear therapy.

Contrast sensitivity and disability glare in patients with dry eye

To evaluate contrast sensitivity and disability glare in patients with dry eye using the Contrast Glaretester 1000. Contrast sensitivity and disability glare were determined in 33 eyes of 33 patients with dry eye and 30 eyes of 30 healthy control subjects for six target sizes with a visual angle of 6.3-0.7 degrees using the Contrast Glaretester 1000, whose working mechanism is similar to that of the conventional perimetry instrument. Contrast sensitivity was significantly worse in dry eye group when viewing all target sizes (reduction of 0.10-0.25 log contrast units, p < 0.01) except at 6.3 degrees. In the presence of glare, differences in log contrast sensitivity between the groups (0.10-0.25 units) were significant (p < 0.01) for all target sizes, with the dry eye group showing worse results. The reduction in contrast sensitivity induced by glare (disability glare) was significantly worse in the dry eye group versus the control group but only for the 2.5-degree size target, where 0.14 log contrast units were lost. Contrast sensitivity with and without glare was significantly reduced in patients with dry eye compared with control subjects, but the number of log contrast units lost with glare (disability glare) was similar in the two groups, except for the 2.5-degree size target.

Increase in central corneal thickness in dry and normal eyes with application of artificial tears: a new diagnostic and follow‐up criterion for dry eye*

To investigate the effect of artificial tear application on central corneal thickness (CCT) in dry and normal eyes. Forty eyes of 40 patients with symptomatic dry eyes and 20 eyes of 20 controls were included in the study. A combination artificial tear therapy was given to both groups for 1 week. The CCT was measured with ultrasonic pachymetry before and after the therapy. In addition, at the beginning of the study, 11 dry eye patients and eight control patients were evaluated separately as a subgroup: they received artificial tears every 10 min for an hour to determine whether this might constitute a diagnostic criterion. Results were analysed with a Wilcoxon test, accepting p < 0.01 as significant. The mean CCT in the dry eye group before and after 1-week therapy was 531.5 +/- 16.5 and 559.6 +/- 26.1 microm, respectively (p < 0.0001); thus yielding an average CCT increase of 28.1 +/- 9.4 microm (=5.30%: 1.65% minimum; 7.03% maximum) from baseline. The mean CCT in the control group before and after 1-week therapy was 549.2 +/- 37.8 and 552.3 +/- 39.8 microm, respectively (p = 0.001); thus, yielding an average CCT increase of 3.1 +/- 1.9 microm (=0.56%: 0.00% minimum; 1.18% maximum) from baseline. When the subgroup was evaluated separately, the average increase from baseline in 11 dry eye patients was 10.4 +/- 4.0 microm (=1.89%: 0.60% minimum; 4.26% maximum) after 1 h of artificial tear application, while it was 2.9 +/- 2.0 microm (=0.51%: 0.00% minimum; 0.58% maximum) in eight control patients (p < 0.0001). The CCT in dry eyes increases rapidly and significantly compared to normal eyes after application of artificial tears. It is suggested that this increase could be used as a criterion in the diagnosis and follow up of dry eyes, and that this increase in thickness should be considered in intra-ocular pressure measurements as well as in refractive surgical procedures.

Distribution of Conjunctival HLA-DR Expression and the Pathogenesis of Damage in Early Dry Eyes

To examine the expression of HLA-DR, a marker of inflammation, in the early stages of dry eye disease and to locate the appearance of this marker on specific areas of the bulbar conjunctiva. Dry eye patients were identified and their condition classified as mild (n = 16) or moderate (n = 16) based on Schirmer testing, vital staining, tear break-up time, and symptom questionnaire scores. Brush cytology was used to collect epithelial cells from the nasal, temporal, and superior conjunctivae of patients and age-matched controls. HLA-DR positive cells were detected by immunohistochemical staining and quantified. Patients with moderate dry eye had the highest rate of conjunctival HLA-DR-positive cells, with significantly higher rates than controls regardless of which region of the conjunctiva was sampled (P < 0.01). The mild dry eye group had similar rates of HLA-DR-positive cells in the superior conjunctival region compared with controls. However, in the nasal and temporal regions, they displayed a significantly higher rate of HLA-DR-positive cells than controls (P < 0.01) and the nasal region showed a significant difference (P < 0.01) when compared with the temporal one. Some of these mild dry eyes had no vital staining. The HLA-DR expression pattern in mild and moderate dry eyes appears to reflect disease progression. Overexpression of HLA-DR in mild dry eyes showing no vital staining suggests that inflammation may be a primary cause of ocular surface damage. These data support the use of immunomodulatory drugs in the treatment of dry eye disease.

Estudio comparativo del test de Schirmer y BUT en relación con la etiología y gravedad del ojo seco

To determine possible differences between the Schirmer test and the tear break up time (BUT) in relation to the etiology and severity of the dry eye syndrome. We present a prospective study of 206 eyes in 106 patients (38 males and 68 females). Both the Schirmer test and BUT were performed on all of them. We divided the patients into ten etiologic groups according to the Madrid triple classification of dry eye etiology and into four groups according to clinical severity. Both the Schirmer test and BUT results decrease according to the severity of symptoms and we found significant differences between clinical groups. In regard to etiology, we found lower values of the Schirmer test especially in immunological, senile and traumatic dry eye groups. BUT measures were lower in immunological, inflammatory and tantalic dry eye groups. Although we found differences between Schirmer test results and BUT values according to dry eye etiology, these differences were only statistically significant between the immunological group and the other groups. Differences between etiological groups decreased with worsening of the illness due to a general affectation of the lacrimal glands.

Reduced Corneal Thickness Values in Postmenopausal Women With Dry Eye

To study and compare the corneal thickness values of postmenopausal women with dry eye and postmenopausal women without dry eye. The corneal thickness value of 30 postmenopausal women with dry eye (dry eye group; aged 52 to 55 years) and 32 postmenopausal women without dry eye (normal group; aged 51 to 55 years) was analyzed with the Orbscan Topography System II. Each woman underwent a tear breakup test, the Schirmer test, fluorescein staining of the cornea, and an analysis of the meibomian gland by slit lamp before corneal thickness measurement. The statistical analysis was performed by means of the unpaired Student t test. The mean corneal thickness value was significantly decreased in postmenopausal women with dry eye (P < 0.001 at each corneal location). The central cornea had the thinnest mean values in dry eyes and normal eyes (533.10 +/- 4.74 microm and 547.63 +/- 15.11 microm, respectively), whereas superonasal cornea had thicker mean values in both groups (632.43 +/- 6.11 microm and 648.78 +/- 14.98 microm in dry eye and normal eyes, respectively). Postmenopausal women with dry eye have lower corneal thickness values than postmenopausal women without dry eye. Special care must be taken with these reduced corneal thickness values when selecting postmenopausal women for surgery involving corneal photoablation.

Sialic Acid in Human Tear Fluid Decreases in Dry Eye

To evaluate the association between tear mucin and dry eye, we compared tear fluid sialic acid concentration in dry eye patients with that in normal volunteers. We also compared the sialic acid concentration with the results of several different types of dry eye examinations. Subjects comprised 16 age-matched, normal healthy controls and 45 dry eye patients. Dry eye examinations included fluorescein staining, rose bengal staining, Schirmer I test, cotton thread test, and fluorescein breakup time. Tear samples were collected with a micropipette after the instillation of 50 microl saline. The sialic acid concentration was measured by high-performance liquid chromatography. The sialic acid concentration was significantly lower in the dry eye group (5.3 +/- 4.3 microg/ml) than in the control group (37.1 +/- 28.3 microg/ml) (P < 0.001). Also, the sialic acid concentration correlated significantly with the results of dry eye examinations (P < 0.0002). The different sialic acid levels in the control and dry eyes may imply differences in the quantity or quality of glycoprotein in tears between these two groups. Thus, sialic acid, a component of mucin, may play a key role in the dry eye condition.

The conjunctival epithelium in dry eye subtypes: Effect of preserved and non-preserved topical treatments

Purpose. To determine the effect of topical treatments on the conjunctiva in dry eye. Methods. N = 134 dry eye subjects were diagnosed using a protocol of McMonnies dry eye symptom survey score > 14, fluorescein break up time (FBUT) < 10s and presence of rose Bengal staining. Differential diagnosis of dry eye subtypes was based on biomicroscopic signs and ocular/medical history. Superficial perilimbal bulbar conjunctival epithelial samples were collected using impression cytology. The nucleo-cytoplasmic ratio (N/C), goblet cell density (GCD) and expression of monoclonal antibodies HLA DR and CD23 were determined. The ocular surface characteristics of untreated subjects, those receiving preserved dry eye treatments and those receiving non-preserved treatments were compared with each other and with controls. Ocular surface characteristics of dry eye subtypes were also examined. Results. An increase in N/C (p = 0.011), reduction in GCD (p = 0.0001) and increase in expression of HLA DR (p = 0.0001) and CD23 (p = 0.0001) were detected in the untreated group compared to controls. No significant differences were found between the group receiving non-preserved dry eye treatments and untreated dry eye group. The group receiving preserved treatments had a reduced GCD (p = 0.0003) and increased expression of HLA DR (p = 0.0003) and CD23 (p = 0.0001) compared to the group receiving non-preserved treatments. Dry eye subtype specific differences in HLA DR and CD23 expression were noted. Conclusions. The conjunctival inflammation and reduced goblet cell density of dry eye is exacerbated by use of preserved topical agents, and is not significantly improved by use of non-preserved artificial tear supplements alone. Therapeutic strategies for dry eye should aim to increase goblet cell density and control ocular surface inflammation.

Decrease in Corneal Sensitivity and Change in Tear Function in Dry Eye

Our purpose was to investigate the relationship between insufficient tear secretion and decreased corneal sensitivity. We studied 59 patients with dry eye, 15 of whom had Sjögren's syndrome (SS), and 26 healthy subjects. Corneal sensitivity was measured by the esthesiometer of Cochet and Bonnet. Schirmer test with or without anesthesia, tear clearance rate, tear function index, and rose bengal and fluorescein staining were also evaluated. The mean corneal sensitivity of either dry-eye group (4.6 +/- 1.2 and 4.5 +/- 1.2 cm for non-SS and SS dry eye, respectively) was significantly lower than that of the control (5.8 +/- 0.4 cm, p < 0.001). Corneal sensitivity correlated significantly with the Schirmer values with anesthesia and the tear function index in the two dry-eye groups and the control (p < 0.05). There were significant relationships between corneal sensitivity and the rose bengal and fluorescein scores in the three groups (p < 0.05). Hyposecretion of tears in dry eye may lead to pathologic changes in corneal epithelium and a decline in corneal sensitivity. Prompt treatment of dry eye is essential to maintain a normal corneal protective mechanism.

Ocular surface cooling in dry eye — a pilot study

Infrared thermography was employed to measure the change in ocular surface temperature on eye opening within agroup of 11 dry-eye patients and seven control subjects. Qualitatively, the colour coded thermograms were found to be disorganised and irregular in the dry-eye group. Quantitatively, the decrease in temperature was found to be much more rapid in the dry-eye group (0.88 ± 0.23°C in 7s) compared with the control group (0.21 ± 0.27°C) (P<0.0001). This faster rate of cooling can be explained in terms of a greater evaporation rate and the increased ocular surface temperature on eye opening in a dry eye. This observation, if confirmed on a larger study group, potentially offers a new, objective, non-invasive system for analysis of the tear-film and dry-eye therapies.

Tear meniscus measurement in the diagnosis of dry eye.

Assessment of the tear film meniscus is a quantitative, minimally invasive, direct measurement of tear film quantity. The aim of this study was to assess the efficacy of tear meniscus parameter measurement in the diagnosis of dry eye. Tear meniscus radius of curvature, height, width and cross-sectional area (TMC, TMH, TMW, XSA) were determined by photographing an optic section of the inferior tear meniscus (colored with a min volume of fluorescein) at 12 x magnification, and then scanning developed images into a computer analysis program. Fifteen dry eye subjects and 15 age-matched controls were assessed. Dry eye subjects satisfied the criteria of a rose bengal staining score >/= 1, and a mean phenol red thread 15s wetted length </= 10 mm. TMC, TMH and XSA were all reduced in magnitude in the dry eye group compared to the control group (mean +/- SD; TMC: 0.314 +/- 0.160 mm vs. 0.545 +/- 0.259 mm, TMH: 0.244 +/- 0.089 mm vs. 0.461 +/- 00.173 mm, XSA: 0.0082 +/- 0.0048 mm2 vs. 0.0176 +/- 0.0103 mm2, ANOVA, p < 0.05). Both TMC and TMH showed good diagnostic accuracy (166.7% and 160% respectively), with a dry eye referent value of </=0.35 mm for each parameter. TMC and TMH also showed strong correlations with the cotton thread test, non-invasive breakup time, and ocular surface staining scores (p < 0.01). TMH was the most powerful predictor of tear film insufficiency. This study has shown tear meniscus assessment to be a useful alternative to existing tests for dry eye.

Infrared thermography of the tear film in dry eye.

Infrared ocular thermograms were recorded for a group of 36 dry eye patients and for 27 age- and sex-matched controls. Mean ocular surface temperature was greater in the dry eye group (32.38 +/- 0.69 degrees C) compared with the control group (31.94 +/- 0.54 degrees C; p < 0.01). In addition, there was a greater variation of temperatures across the ocular surface in the dry eye group, illustrated by the difference in temperature between the limbus and the centre of the cornea (0.64 +/- 0.20 degrees C in dry eye patients compared with 0.41 +/- 0.20 degrees C in the control group; p < 0.001). This parameter was also shown to be greater in dry eye patients who displayed either a fast tear break-up time or a poor Schirmer's test result. Infrared thermography is a non-invasive and objective technique that may prove a useful research tool for study of the tear film, its deficiencies and its various treatment modalities.