Effect of light-emitting diodes with different color rendering indexes on the ocular tissues of rat

To investigate the effectiveness of lacrimal gland ultrasonography in the assessment of chronic ocular graft-versus-host-disease (oGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and to establish the correlation between the ocular surface and ultrasonographic results. The cross-sectional study included 57 participants aged 18 and older, who were at least 100 days after allo-HSCT. The study was conducted at the oGVHD clinic of Peking University People's Hospital between March to June 2023. Patients were categorized into groups according to the International Chronic oGVHD (ICCGVHD) consensus group diagnostic criteria or the 2005 National Institutes of Health (NIH) classification criteria for Chronic GVHD. Demographics and transplantation-related information were collected for all participants, including age, gender, donor-recipient HLA matching, donor-recipient ABO matching, donor-recipient gender combination and duration after allo-HSCT. The disease activity of oGVHD and the severity of ocular surface involvement were assessed using various parameters such as Ocular Surface Disease Index (OSDI), Schirmer test, tear film break-up time (BUT), tear meniscus height, corneal/conjunctival staining and meibomian gland dropout. Lacrimal gland structures were assessed by B-mode and Doppler ultrasonography to measure parameters such as the long diameter, thick diameter, homogeneity and parenchymal vascularization. Statistical analyses were performed to determine differences in ocular surface conditions and lacrimal gland ultrasonographic parameters between groups as well as to determine the correlation between ocular surface condition and lacrimal gland ultrasonographic findings. (1) Patients with definite and probable oGVHD exhibited a significantly longer duration after allo-HSCT compared to non-oGVHD patients (H=11.264, p<0.01), The median durations were 247(164,894) days and 525(310,928) days, respectively, compared to 204(169,323.25) days for non-oGVHD patients. (2) Compared to non-oGVHD patients, both definite oGVHD patients and probable oGVHD patients showed lower average of Schirmer test (H=31.188, p<0.01), TBUT (H=11.853, p<0.01), tear meniscus height (H=13.630, p<0.01) and higher average of OSDI (F=27.992, p<0.01), corneal staining scores (χ²=23.66, p<0.05) and temporal conjunctival staining scores (χ²=14.84, p<0.05). (3) The B-mode and Doppler ultrasonography parameters in lacrimal glands including long diameter, thick diameter, homogeneity and parenchymal vascularization did not exhibit significant differences between the three groups. (4) The long diameter in lacrimal ultrasonography had significantly positive correlations with tear meniscus height (r=0.297, p<0.05) and significantly negative correlations with temporal conjunctival staining scores (r=-0.313, p<0.05) and staining total scores (r=-0.285, p<0.05). The thick diameter in lacrimal ultrasonography demonstrated significantly positive correlations with tear meniscus height (r=0.404, p<0.01), and significantly negative correlations with OSDI (r=-0.273, p<0.05), corneal staining scores (r=-0.264, p<0.05), nasal conjunctival staining scores (r=-0.271, p<0.05) and staining total scores (r=-0.312, p<0.05). Homogeneity and parenchymal vascularization were not found to be significantly correlated with ocular surface status. The ocular surface condition in oGVHD patients is worse than that observed in non-GVHD patients. The main manifestations include keratoconjunctival injury and a reduction in tear secretion and tear film stability. These effects appear to be a common result of chemoradiotherapy-induced inflammation and rejection-associated responses. There were no significant differences in the morphology of lacrimal glands as revealed by ultrasonography. This suggests that ocular rejection may not be the primary cause of lacrimal gland changes in oGVHD patients. While ultrasonography can provide insight into tear secretion, its efficacy in diagnosing oGVHD appears limited.

To investigate the regulatory roles of the members of the peroxisome proliferator-activated receptor (PPAR) family in lacrimal gland dysfunction under conditions of desiccating stress or diabetes. Quantitative polymerase chain reaction (qPCR) was used to examine the expression of PPARs in the cornea, conjunctiva, meibomian gland, and lacrimal gland in adult rats. The rats were divided into 3 groups: a control group, dry eye group, and diabetic group. The phenol red threads test, tear film break-up time (BUT) test and fluorescein staining were carried out to evaluate the development of dry eye. Based on bioinformatics research, qPCR was used to examine the expression level of PPARγ, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), sirtuin 1 (Sirt1), myeloid differentiation factor 88 (MyD88) and transforming growth factor-β (TGF-β) in the lacrimal glands. PPARα and PPARβ/δ were mainly expressed in the conjunctiva and the lacrimal gland, respectively. However, PPARγ was expressed in both the conjunctiva and lacrimal gland, at much higher levels than those measured for PPARα and PPARβ/δ. Dry eye rats and diabetic rats both showed decreased tear secretion, shortened BUT, and increased corneal staining. Significant changes in gene expression were observed compared with the control group. In the lacrimal glands of dry eye rats and diabetic rats, expression of PPARγ decreased (P<0.05), expression of Sirt1 also decreased (P<0.01), whereas expression of TNF-α, IL-1β, IL-6, MyD88, and TGF-β increased (P<0.05). Among PPARs, PPARγ might play a dominant role in the regulation of metabolic- and inflammatory-signaling pathways on the ocular surfaces and in lacrimal glands. Down-regulation of PPARγ is highly relevant to lacrimal gland dysfunction under desiccating-stress and diabetic conditions. PPARγ, thus, is a potential therapeutic target in the treatment of environment- or diabetes-induced dry eye diseases.

High-Fat Diet–Induced Functional and Pathologic Changes in Lacrimal Gland

Lacrimal Gland in Sjögren's Syndrome

Previous studies have shown that ovariectomy (OVX) induces lacrimal gland regression and that androgens are implicated. This study explored the effects of estrogen and androgen on tear secretion and matrix metalloproteinase 2 (MMP-2) expression in lacrimal glands of ovariectomized rats. Sixty-four adult female Wistar rats were randomly divided into three groups (control, sham operated, and OVX). Bilateral OVX was performed in the OVX group. After 5 months, the OVX group was further divided into six subgroups receiving topical ophthalmic or systemic treatment with corn oil vehicle, estradiol, or testosterone for 6 weeks. Schirmer test (SIT), assessment of tear film breakup time (BUT), corneal fluorescein staining, and measurement of estradiol and testosterone levels were performed before OVX and 1, 2, 3, 4, and 5 months after OVX, as well as after 6 weeks of treatment. Lacrimal glands were assessed for MMP-2 mRNA and protein expression. The mean (SD) tear film BUT decreased from 10.53 (0.79) to 9.98 (1.00) seconds (P < 0.01) in the first month after OVX, and the mean (SD) SIT result decreased by 50% from 7.32 (1.61) to 3.39 (1.15) mm (P < 0.01) in the third month after OVX. The mean (SD) corneal fluorescein staining score increased from 0.35 (0.11) to 6.02 (1.34) (P < 0.05) in the fourth month after OVX. The values increased or decreased in parallel with the time course (P < 0.01). In serum, ovariectomy resulted in a mean (SD) decline in estradiol levels from 44.38 (9.78) to 23.00 (3.78) pg/mL (P < 0.01), and the mean (SD) testosterone levels decreased from 2.42 (0.26) to 1.87 (0.15) ng/mL (P < 0.05). The mean (SD) estradiol level was elevated to 35.38 (3.34) pg/mL by systemic estradiol administration for 6 weeks, which also led to further mean (SD) decreases in tear film BUT from 5.28 (0.81) to 3.65 (0.55) seconds (P < 0.01) and in SIT result from 2.19 (1.01) to 1.47 (0.85) mm (P < 0.05), as well as a higher mean (SD) corneal fluorescein staining score from 7.39 (1.34) to 9.89 (1.27) (P < 0.05). However, the mean (SD) testosterone level was increased to 3.53 (0.67) ng/mL by systemic testosterone administration for 6 weeks. As a result, the mean (SD) tear film BUT increased from 5.08 (0.40) to 6.03 (1.48) seconds (P < 0.05), and the mean (SD) SIT result increased from 2.38 (1.20) to 3.66 (1.90) mm (P < 0.05). The mean (SD) corneal fluorescein staining score declined from 7.45 (0.73) to 4.56 (1.21) (P < 0.05). In the nontreated OVX group, the mean (SD) MMP-2 mRNA (0.66 [0.10]) and protein (0.55 [0.13]) expression in lacrimal glands was significantly increased compared with that in the sham-operated group (0.50 [0.09] and 0.40 [0.07], respectively) (P < 0.05). Systemic estradiol administration further increased the mean (SD) MMP-2 mRNA (0.83 [0.10]) and protein (0.69 [0.12]) expression (P < 0.05), while systemic testosterone administration decreased the mean (SD) MMP-2 mRNA (0.12 [0.04]) and protein (0.27 [0.07]) expression (P < 0.01). Topical ophthalmic administration of two sex hormones had no effect on the mean (SD) MMP-2 mRNA (0.59 [0.12] for estradiol and 0.57 [0.14] for testosterone) or protein (0.49 [0.11] for estradiol and 0.46 [0.13] for testosterone) expression (P > 0.05). Ovariectomy-induced ocular surface impairment may be associated with androgen deficiency. A pathogenetic role for estrogen in dry eye may involve upregulation of MMP-2 expression, while androgen suppresses MMP-2 expression.

PurposeTo determine the effect of obstructive sleep apnea syndrome (OSA) on lacrimal gland function and its mechanism.MethodsMale mice aged seven to eight weeks were housed in cages with cyclic intermittent hypoxia to mimic OSA, and the control group was kept in a normal environment. Slit-lamp observation, fluorescein staining, and corneal sensitivity detection are used to assess cornea changes. Tear secretion was detected by phenol red cotton thread, and the pathological changes of lacrimal gland were observed by hematoxylin and eosin staining, oil red O staining, cholesterol and triglyceride kits, immunofluorescence staining, immunohistochemical staining, real-time polymerase chain reaction, transmission electron microscopy, and Western blot.ResultsStudies revealed a decreased tear secretion, corneal epithelial defects and corneal hypersensitivity. Myoepithelial cell damage, abnormal lipid accumulation, reduced cell proliferation, increased apoptosis and inflammatory cell infiltration in the lacrimal gland were also seen. Hifα and NF-κB signaling pathways, moreover, were activated, while Pparα was downregulated, in the lacrimal glands of OSA mice. Fenofibrate treatment significantly alleviated pathological changes of the lacrimal gland induced by OSA.ConclusionOSA disturbs the Hifα/Pparα/NF-κB signaling axis, which affects lacrimal gland structure and function and induces dry eye.

Perspective: Lacrimal gland biopsy, is it important?

Objective To explore the occurring and developing characteristics of dry eye syndrome in type 1 diabetic mouse model induced with streptozotocin (STZ)-intraperitoneal injection. Methods Completely randomized design method was performed.Sixty SPF degree male C57BL/6 mice (6-8 weeks old) was randomly divided into diabetic group and control group, which were intraperitoneally injected with citrate buffer and STZ-citrate buffer (50 mg/kg per day), respectively.The average weight, blood glucose level and lacrimal gland weight were examined before injection and 1 month, 2 months, 4 months after the last injection; meanwhile, phenol cotton thread and rose bengal staining methods were used to check tear formation and ocular surface condition; corneal perception meter was used to test corneal sensitivity; periodic acid-schiff (PAS) staining method was used to test the density of conjunctival goblet cells; histopathological staining and Masson staining methods were used to test the tissue changes of lacrimal gland. Results Compared with before injections, the body weight and lacrimal gland weight in diabetic group were not significantly changed 1 month, 2 months and 4 months after injection (all at P>0.05), but these measurements in diabetic group 1 month, 2 months and 4 months after injection were significantly lower than those in control group at corresponding time points (all at P<0.05). Compared with before injections and control group at corresponding time points, the blood glucose level were dramatically higher and the tear formation were significantly decreased in diabetic group at 1 month, 2 months, 4 months after injection (all at P<0.05). The ocular surface of diabetic model mice showed positive rose bengal staining 2 months after STZ injections.The corneal sensitivities were significantly lower in diabetic model mice 2 months and 4 months after injection than those before injection and in control group at corresponding time points (all at P<0.05). The density of conjunctival goblet cells in diabetic group 4 months after injection was significantly decreased than those before injection in diabetic group and 4 months after injection in control group (all at P<0.05). The apparent collagen fibrosis and inflammatory cell infiltration were observed at lacrimal gland in diabetic model mice 4 months after injection. Conclusions The major early stage manifestations of STZ induced type 1 diabetes mice include retarded growth of lacrimal gland and decreased tear secretion volume, which gradually develop along the course of diabetes; in the later stage, the manifestations include decreased corneal sensitivity, ocular structural damage, structural changes of lacrimal gland and decreased conjunctival goblet cell density. Key words: Diabetes mellitus; Dry eye; Tear formation; Lacrimal gland; Corneal sensitivity

Objective To explore the relationships of neutrophil gelatinase-associated lipocalin (NGAL) with severity of skin lesions in children with psoriasis and peripheral neutrophil count, and to evaluate in vitro effect of NGAL on expression of tumor necrosis factor-α (TNF-α) and interleukin-22 (IL-22) by a human immortalized keratinocyte cell line HaCaT. Methods From January 1st 2017 to December 31st 2018, 98 children who newly developed psoriasis were enrolled from Department of Dermatology of 6 hospitals in China, including 51 males and 47 females. Their age was 7.00 ± 2.99 years (range: 3-14 years) , and their course of disease was 7.4 ± 5.85 days (range: 3-28 days) . The serum level of NGAL was detected in all the patients before and two weeks after treatment, and the relationships of NGAL with psoriasis area and severity index (PASI) scores and peripheral neutrophil count were evaluated. Western blot analysis and reverse-transcription (RT) -PCR were performed to determine the protein and mRNA expression of TNF-α and IL-22 in HaCaT cells, respectively, after 12-hour treatment with NGAL at concentrations of 0 (control group) , 0.125, 0.25, 0.5, 1 mg/L. Statistical analysis was carried out with SPSS 16 software. by using t test and one-way analysis of variance. Results After 2-week treatment, the PASI score, neutrophil count and NGAL level in children with psoriasis significantly decreased (1.80 ± 1.19, [6.16 ± 0.76] × 109/L, 90.86 ± 0.75 μg/L, respectively) compared with those before the treatment (10.38 ± 3.42, [11.01 ± 2.85] × 109/L, 113.48 ± 21.26 μg/L, respectively; t = 31.42, 18.34, 16.37 respectively, all P < 0.001) . Before the treatment, the serum level of NGAL in the patients was positively correlated with the PASI score and peripheral neutrophil count (r = 0.918, 0.799 respectively, both P < 0.05) . The mRNA and protein expression of IL-22 in HaCaT cells significantly differed among these groups treated with different concentrations of NGAL (F = 176.31, 296.96 respectively, both P < 0.001) , so did the mRNA and protein expression of TNF-α (F = 193.28, 318.80 respectively, both P < 0.001) . Additionally, the protein and mRNA expression of IL-22 and TNF-α in HaCaT cells was significantly higher in the 0.125-, 0.25-, 0.5- and 1-mg/L NGAL group than in the control group (all P < 0.05) . The NGAL level was positively correlated with the protein and mRNA expression of TNF-α and IL-22 in HaCaT cells (all P < 0.05) . Conclusions The serum level of NGAL was high in children with psoriasis, and positively correlated with severity of skin lesions and peripheral neutrophil count. NGAL can upregulate the expression of TNF-α and IL-22 in HaCaT cells in vitro. Key words: Psoriasis; Child; Tumor necrosis factor-alpha; Interleukin-22; Neutrophil gelatinase associated lipocalin

Purpose:This study evaluates the radiographic appearance of lacrimal gland tissue after placement of a glaucoma drainage implant (GDI) to characterize the impact of the device on the gland's imaging patterns.Methods:We performed retrospective chart review of departmental records at two urban academic medical centers, which were systematically searched using procedure codes to identify adult glaucoma patients who underwent unilateral superotemporal GDI from January 1995 to December 2015. Radiology records were cross-checked to identify the subset of patients who underwent postoperative orbital CT or MRI. Chart review collected data on glaucoma diagnosis, management, examination findings, and clinical complaints. Imaging studies were reviewed for orbital changes using qualitative assessment of the radiographic appearances and computer-guided calculations to quantify asymmetries.Results:A review of all eye operations in the inclusion period identified 315 patients with GDI, 13 of whom were eligible for inclusion. Elapsed time from device placement to imaging averaged 41.9 months, and the average clinical follow-up was 56.4 months. Radiographic lacrimal gland changes were appreciable in 69% (9 of 13) of patients, most commonly with posterior displacement and flattening of the gland (7 of 13). ImageJ analysis revealed significantly smaller lacrimal glands in orbits with GDI (P = 0.04). No clear correlation was found between gland changes and clinical dry eye symptoms.Conclusion:GDI placement was associated with radiographically-appreciable lacrimal gland changes in two-thirds of patients, with changes occurring in a predictable pattern of lacrimal gland flattening, posteriorization, and volume loss. Radiographic changes correlated with clinical symptoms in few patients.

This study investigated the impact of hyperglycemia in type 2 diabetes mellitus (T2DM) on the circadian rhythms and function of lacrimal glands (LGs) in contributing to dry eye syndrome. We assessed the effects of hyperglycemia on circadian gene expression, immune cell recruitment, neural activity, and metabolic pathways, and evaluated the effectiveness of insulin in restoring normal LG function. Using a T2DM mouse model (db/db mice), circadian transcriptomic changes in LGs were analyzed through RNA sequencing over a 24-hour period. Rhythmic expression of core clock genes, immune and neural activity, and metabolic pathways were evaluated. The effects of insulin treatment on these parameters were also assessed. Hyperglycemia disrupted the circadian expression of core clock genes in LGs, leading to a 50% reduction in rhythmic gene expression. This was associated with altered immune cell recruitment, impaired neural activity, and metabolic changes. Insulin treatment lowered blood glucose levels but did not restore normal circadian function or tear secretion, exacerbating dry eye syndrome in diabetic mice. T2DM significantly disrupts circadian rhythms and function in lacrimal glands, contributing to dry eye syndrome. The limited efficacy of insulin in restoring circadian regulation suggests that hyperglycemia-induced dysfunction in LGs is not solely dependent on blood glucose levels, highlighting the need for therapies targeting circadian rhythms in diabetic ocular complications.

To explore changes in lacrimal gland and tear inflammatory cytokines in thyroid-associated ophthalmopathy (TAO) patients. Patients with TAO were divided into active and inactive TAO groups. These two TAO groups and the control completed the Ocular Surface Disease Index (OSDI), underwent thorough ophthalmologic examinations, and underwent orbital magnetic resonance scan to measure the size of the lacrimal gland. Basal tears, reflex tears induced by nasal stimulation and serum samples, were collected to analyze the concentrations of interleukin (IL)-1β, IL-6, IL-7, IL-17A, interferon γ, and tumor necrosis factor α by multiplex bead analysis. The coronal lacrimal gland area was significantly larger in active (P < 0.000) and inactive TAO (P = 0.002) than in the control, and the axial lacrimal gland area was significantly larger in active (P < 0.000) and inactive TAO (P = 0.001) than in the control. The coronal lacrimal gland width was significantly greater in active (P < 0.000) and inactive TAO (P = 0.001) than in the control, and axial lacrimal gland width was significantly greater in active (P < 0.000) and inactive TAO (P = 0.035) than in the control. In TAO patients, the axial area was positively correlated with IL-1β and IL-17A concentrations in tears (r = 0.357, P = 0.013; r = 0.359, P = 0.012), and both coronal and axial areas were positively correlated with IL-6 concentrations in tears (r = 0.346, P = 0.016; r = 0.340, P = 0.018). Increased inflammatory cytokines play an important role in ocular surface damages, and might be associated with the inflammatory involvement of the lacrimal gland.

Therapeutic doses of radiation (RTx) causes dry eye syndrome (DES), dry mouth, and as in other sicca syndromes, they are incurable. The aims of this work are as follows: (a) to evaluate a mouse model of DES induced by clinically relevant doses of radiation, and (b) to evaluate the protective effect of erythropoietin (Epo) in preventing DES. C3H female mice were subjected to five sessions of RTx, with or without pre-RTx retroductal administration of the AdLTR2EF1a-hEPO (AdEpo) vector in the salivary glands (SG), and compared with naïve controls at Day 10 (10d) (8 Gy fractions) and 56 days (56d) (6 Gy fractions) after RTx treatment. Mice were tested for changes in lacrimal glands (LG), tear secretion (phenol red thread), weight, hematocrit (Hct), and markers of inflammation, as well as microvessels and oxidative damage. Tear secretion was reduced in both RTx groups, compared to controls, by 10d. This was also seen at 56d in RTx but not AdEpo+RTx group. Hct was significantly higher in all AdEpo+RTx mice at 10d and 56d. Corneal epithelium was significantly thinner at 10d in the RTx group compared with AdEpo+RTx or the control mice. There was a significant reduction at 10d in vascular endothelial growth factor (VEGF)-R2 in LG in the RTx group that was prevented in the AdEpo+RTx group. In conclusion, RTx is able to induce DES in mice. AdEpo administration protected corneal epithelia and resulted in some recovery of LG function, supporting the value of further studies using gene therapy for extraglandular diseases.

Dry eye disease can be a consequence of lacrimal gland insufficiency in Sjögren’s Syndrome or increased tear film evaporation despite normal lacrimal gland function. To determine if there is a correlation between severity effects in these models and underlying pathophysiological responses, we compared the time dependent changes in each of these parameters that occur during a 6 week period. Dry eye was induced in 6-week-old female C57BL/6 mice by exposing them to an Intelligently Controlled Environmental System (ICES). Sixty mice were housed in ICES for 1, 2, 4 and 6 weeks respectively. Twelve were raised in normal environment and received subcutaneous injections of scopolamine hydrobromide (SCOP) 3 times daily for 5 days. Another sixty mice were housed in a normal environment and received no treatment. Corneal fluorescein staining along with corneal MMP-9 and caspase-3 level measurements were performed in parallel with the TUNEL assay. Interleukin-17(IL-17), IL-23, IL-6, IL-1, TNF-α, IFN-γ and TGF-β2 levels were estimated by real-time PCR measurements of conjunctival and lacrimal gland samples (LGs). Immunohistochemistry of excised LGs along with flow cytometry in cervical lymph nodes evaluated immune cell infiltration. Light and transmission electron microscopy studies evaluated LGs cytoarchitectural changes. ICES induced corneal epithelial destruction and apoptosis peaked at 2 weeks and kept stable in the following 4 weeks. In the ICES group, lacrimal gland proinflammatory cytokine level increases were much lower than those in the SCOP group. In accord with the lower proinflammatory cytokine levels, in the ICES group, lacrimal gland cytosolic vesicular density and size exceeded that in the SCOP group. ICES and SCOP induced murine dry eye effects became progressively more severe over a two week period. Subsequently, the disease process stabilized for the next four weeks. ICES induced local effects in the ocular surface, but failed to elicit lacrimal gland inflammation and cytoarchitectural changes, which accounts for less dry eye severity in the ICES model than that in the SCOP model.

The objectives of this study were: (i) to determine tear film breakup times (BUTs) in young healthy cats; (ii) to determine tear film BUTs in feline eyes within 8-20 h following general anesthesia; (iii) to determine if tear film BUTs vary significantly preoperatively when compared with values obtained 8-20 h postoperatively; (iv) to determine if Schirmer tear test (STT) values correlate with tear film BUTs in young healthy cats; and (v) to determine if the isolation of particular etiologic agents from conjunctival swabs of healthy cats affects tear film BUTs. We studied eighteen healthy Domestic Short-haired (n=14) and Domestic Long-haired (n=4) cats, with normal ocular examinations, ranging in age from 0.5 to 3 years. Complete ophthalmic examinations, including tear film BUTs, were performed on all cats. Conjunctival swabs from each eye of all cats and blood samples from all cats were collected and submitted for polymerase chain reaction screening for feline herpes virus, Chlamydophila felis, Mycoplasma spp., and calicivirus. In 10 of 18 cats, STT values and tear film BUTs were measured before general anesthesia was administered and again within 8-20 h following the end of anesthesia. Mean preanesthesia tear film BUTs for all 18 cats were 17.4+/-4.6 s OD and 16.0+/-4.5 s OS. Mean postanesthesia tear film BUT results were 12.5+/-4.3 and 13.1+/-4.0 s OD and OS, respectively. Postanesthesia tear film BUTs were significantly more rapid than those measured before anesthesia (OD only). There was also a positive correlation, both before and after anesthesia, between STT values in both eyes (OU) and tear film BUTs OU. The isolation or lack of isolation of conjunctival microorganisms using PCR did not significantly affect tear film BUTs. Mean tear film BUT in young healthy domestic cats is 16.7+/-4.5 s. Tear BUT is positively correlated with STT values. Although mean tear film BUTs OD at 8-20 h following anesthesia were more rapid than preanesthesia values, this difference did not appear clinically relevant.