Effect of light intensity on the tear production, central corneal thickness, and intraocular pressure in broiler chickens.

OBJECTIVE: The objective of the present study was to examine the effect of different light intensities on tear production, corneal thickness, and intraocular pressure in broilers. ANIMALS STUDIED: Both eyes of 72 male broilers were evaluated in this study. MATERIALS AND METHODS: Broilers were divided into the following three groups: low light intensity (n = 24, 5 lux), moderate light intensity (n = 24, 20 lux), and high light intensity (n = 24, 80 lux). The eyes of all birds (n = 72) underwent a complete ophthalmic examination, which included the Schirmer tear test (STT-I), intraocular pressure (IOP), and the central cornea thickness measurement (CCT). The effect of light intensity on the Schirmer test, intraocular pressure, and central corneal thickness values was examined at eye and animal level (right and left eyes separately and cumulatively/no distinguishing left or right) by using one-way ANOVA. RESULTS: At the animal level, without discrimination of left and right eye measurements, statistically significant differences were found between 5-20 and 20-80 lux groups on IOP measurements (p < .05). The difference in CCT measurements between the 5 and 20 lux groups was statistically significant (p < .05), and the corneal thickness of the 5 lux group animals was found to be statistically significant and higher than the 20 lux group (p < .05). CONCLUSIONS: In conclusion, light intensity has an influence on eye health in broilers. Present results may attribute to the future studies as a reference value for broilers raised under different light intensities.

Effects of intense pulsed light treatment on tear cytokines and clinical outcomes in meibomian gland dysfunction.

Meibomian gland dysfunction (MGD) has become a prevalent ocular surface disorder. Its pathogenesis is regarded as a self-perpetuating inflammatory vicious circle. Intense Pulsed Light (IPL) treatment was recently applied to improve the meibomian gland function and reduce symptoms of MGD. However, studies investigating the change of specific inflammatory cytokines during IPL treatment remained sparse. To further figure out how IPL treatment modulates the inflammatory cytokines in tears of MGD, we therefore performed a cross-sectional study and enrolled 32 patients from March 2019 to December 2020. The patients received 3 sessions of IPL treatment (10 to 16 J/cm2) at 4-week interval. The signs and symptoms of MGD were evaluated by ocular surface disease index (OSDI), tear film breakup time (TBUT), and meibomian gland yield secretion score (MGYSS). The clinical evaluators and tear samples were analyzed at baseline and at each IPL treatment session. Concentrations of (chemokine ligand) CXCL1, (C-C motif chemokine) CCL11, (tumor necrosis factor) TNF-α, (interferon) IFN-γ, (interleukin) IL-2, IL-6 and (tissue inhibitor of metalloproteinase) TIMP-1were measured by Quantibody Human Dry Eye Disease Array1. OSDI significantly decreased after IPL treatment compared with baseline. TBUT and MGYSS increased consecutively during treatment. CXCL1, CCL11, TNF-α, IFN-γ, IL-2, IL-6 presented significantly decrease and TIMP-1 showed significantly increase from the pretreatment baseline. The changed concentrations of TNF-α, IFN-γ, IL-2, TIMP-1 correlated with TBUT, the changed values of CXCL1, TNF-α, IFN-γ, CCL11, IL-2, IL-6, TIMP-1 correlated with MGYSS, and the changed concentrations of CXCL1, IFN-γ, CCL11, IL-2, IL-6 correlated with TIMP-1. The data supported IPL treatment could significantly relieve both signs and symptoms of MGD. The therapeutic effect of IPL treatment may originate from regulation of inflammatory cytokines including CXCL1, TNF-α, IFN-γ, CCL11, IL-2, IL-6, and TIMP-1.

Clinical and Demographic Characteristics of Tearing in Patients after Radioiodine Ablation for Differentiated Thyroid Cancer.

Background: Radioiodine ablation is a frequent procedure for the management of thyroid cancer. In several cases, this treatment is followed by secondary acquired nasolacrimal duct obstruction (SALDO). Risk factors for the development of SALDO are not defined yet.Aim - to provide clinical and demographic characteristics of tearing in patients after radioiodine treatment.Materials and methods: Material was obtained by a phone survey of 588 patients who underwent radioiodine treatment. Age and gender of the respondent, strength of administered medication, and time since the end of treatment were taken into account. Patients were asked if they had dry mouth and/or tearing at the time of the survey. Differences in values were found using parametric and nonparametric criteria, Pearson's χ2 test. Differences were considered statistically significant at p ≤ 0.05.Results: Severe tearing was reported by 8.8% of patients after single-dose radioiodine treatment and 23.9% of patients after repeated one. The age of patients with severe tearing and without it showed statistically significant difference in patients after single-dose radioiodine treatment and no statistically significant difference in patients after repeated radioiodine treatment. Administration of 4 GBq or more in patients aged 61-71 years results in 4-fold increase of the risk of severe tearing. Dry mouth causes 3.6-fold increase of the risk of developing severe tearing.Conclusion: Finding risk factors for SALDO development after radioiodine therapy in the future will contribute to an individualized approach to the prevention of this complication. Development of preventive measures is one of the tasks facing researchers.

Investigation of light-induced lacrimation and pupillary responses in episodic migraine.

The purpose of this pilot study was to investigate the light-induced pupillary and lacrimation responses mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) in migraine. Ten participants with episodic migraine and normal tear production, as well as eleven visually normal controls participated in this study. Following an initial baseline trial (no light flash), participants received seven incremental and alternating red and blue light flashes. Pupillometry recording of the left eye and a 1-min anesthetized Schirmer's test of the right eye (using 0.5% proparacaine) were performed simultaneously. Intrinsic and extrinsic ipRGC photoactivities did not differ between migraine participants and controls across all intensities and wavelengths. Migraine participants, however, had significantly lower lacrimation than controls following the highest blue intensity. A positive correlation was found between melanopsin-driven post-illumination pupillary responses and lacrimation following blue stimulation in both groups. Our results show that participants with self-reported photophobia have normal ipRGC-driven responses, suggesting that photophobia and pupillary function may be mediated by distinct ipRGC circuits. The positive correlation between melanopsin-driven pupillary responses and light-induced lacrimation suggests the afferent arm of the light-induced lacrimation reflex is melanopsin-mediated and functions normally in migraine. Lastly, the reduced melanopsin-mediated lacrimation at the highest stimulus suggests the efferent arm of the lacrimation reflex is attenuated under certain conditions, which may be a harbinger of dry eye in migraine.

Intense Pulsed Light Therapy for Patients with Meibomian Gland Dysfunction and Ocular Demodex Infestation.

To observe the clinical changes of meibomian gland dysfunctipn (MGD) and ocular Demodex infestation after intense pulsed light (IPL) treatment to further examine the mechanism of IPL treating patients with MGD and ocular Demodex infestation. The medical records of 25 patients (49 eyes) with MGD treated with IPL, were retrospectively examined to determine outcomes. Associated ocular-surface parameters (ocular surface disease index, OSDI; lipid layer thickness, LLT; noninvasive first breakup time, NIF-BUT; noninvasive average breakup time, NIAvg-BUT; tear film breakup area, TBUA; Schirmer I Test, SIT; corneal fluorescein staining, CFS), eyelid margin abnormalities, meibum quality and expressibility, MG morphological parameters (macrostructure and microstructure), and the number of Demodex infestation were examined before and after treatment. The MG microstructure and the Demodex infestation were examined via in vivo confocal microscopy (IVCM). The results showed that there were statistically significant differences in associated ocular-surface parameters (all P<0.05) before and after IPL treatment, except SIT (P=0.065). Eyelid margin abnormalities, meibum quality and expressibility obviously improved in upper and lower eyelid after IPL treatment (all P<0.0001). MG macrostructure (MG dropouts) decreased in upper (P=0.002) and lower eyelid (P=0.001) after IPL treatment. The nine parameters of MG microstructure in upper and lower eyelid all distinctly improved after IPL treatment (all P<0.0001). The mean number of Demodex mites on the upper lid margin (6.59±7.16 to 3.12±3.81/9 eyelashes) and lower lid margin (2.55±2.11 to 1.29±1.53/9 eyelashes) significantly reduced after IPL treatment (all P<0.0001). The Demodex eradication rate was 20% (8/40) in upper lid margin and 34.15% (14/41) in lower lid margin. These findings indicate that IPL shows great therapeutic potential for patients of MGD and ocular Demodex infestation.

Tear-film dynamics by combining double-pass images, pupil retro-illumination, and contrast sensitivity.

Tear-film dynamics were analyzed by a synchronizing recording of double-pass (DP) and pupil retro-illumination (RI) images with contrast sensitivity (CS) measurements. Simultaneous DP and RI images were acquired in three subjects wearing contact lenses while keeping the eye open. Changes in contrast sensitivity for an 18 c/deg green grating were also estimated. From the DP retinal images, the effect of the tear film is described through the objective scattering index (OSI). This presented a negative correlation with the increase in CS during tear-film deterioration (as observed by RI imaging). These results show a relationship between visual outcome degradation due to tear-film breakup and the increase in intraocular scattering. This work shows a combined methodology for the evaluation of tear-film dynamics.

Intense pulsed light treatment and meibomian gland expression for moderate to advanced meibomian gland dysfunction.

BACKGROUND: The aim was to evaluate the efficacy of periocular intense pulsed light therapy combined with meibomian gland expression for chronic dry eye due to moderate to advanced meibomian gland dysfunction. METHODS: This single-institution, open-label prospective study involved 26 participants who received bilateral treatments using a proprietary intense pulsed light device (E > Eye, E-Swin, Paris, France) combined with therapeutic meibomian gland expression at baseline, Week 2 and Week 6. Clinical evaluations performed at baseline, Week 4, Week 8 and Week 12 were symptom scores (Ocular Surface Disease Index [OSDI], Ocular Comfort Index [OCI], daily lubricant use, tear break-up time and ocular surface staining). Tear secretion, tear osmolarity, InflammaDry tear immunoassay, corneal sensation, meibomian secretion quality and expressibility, bulbar conjunctival, limbal and lid margin redness and eyelid margin bacterial swab for cultures and colony counts were performed at baseline and Week 8 only. RESULTS: Significant improvements occurred at Week 8 in meibomian gland expressibility (p = 0.002), meibum quality (p = 0.006), tear break-up time (p = 0.002), corneal staining (p = 0.001), lid margin redness (p = 0.001), bulbar redness (p = 0.05) and limbal redness (p = 0.001). Symptom survey outcomes, eyelid margin bacteria colony counts, Schirmer I test, tear osmolarity, corneal sensitivity and daily lubricant use were unchanged. At Week 12, significant improvements in symptoms (OSDI p = 0.025; OCI p = 0.003), tear break-up time (p = 0.001) and corneal staining (p = 0.001) occurred. Improvement in OSDI score was correlated to the improvement in ocular surface staining (R = 0.43, p = 0.03) and associated with baseline meibomian gland expressibility (Kendall tau: the distributions are ordered the same, p = 0.1). There were no adverse effects of treatment. CONCLUSIONS: Serial intense pulsed light therapy combined with meibomian gland expression significantly improved dry eye symptoms and clinical signs, including meibomian gland secretion quality and expressibility and ocular surface inflammation. Treatment effects were cumulative and sustained for at least six weeks after the final treatment.

Influence of Light Emitting Diode-Derived Blue Light Overexposure on Mouse Ocular Surface.

PURPOSE: To investigate the influence of overexposure to light emitting diode (LED)-derived light with various wavelengths on mouse ocular surface. METHODS: LEDs with various wavelengths were used to irradiate C57BL/6 mice at an energy dose of 50 J/cm2, twice a day, for 10 consecutive days. The red, green, and blue groups represented wavelengths of 630 nm, 525 nm, and 410 nm, respectively. The untouched group (UT) was not exposed to LED light and served as the untreated control. Tear volume, tear film break-up time (TBUT), and corneal fluorescein staining scores were measured on days 1, 3, 5, 7, and 10. Levels of interferon (IFN)-γ, interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α were measured in the cornea and conjunctiva using a multiplex immunobead assay at day 10. Levels of malondialdehyde (MDA) were measured with an enzyme-linked immunosorbent assay. Flow cytometry, 2'7'-dichlorofluorescein diacetate (DCF-DA) assay, histologic analysis, immunohistochemistry with 4-hydroxynonenal, and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining were also performed. RESULTS: TBUT of the blue group showed significant decreases at days 7 and 10, compared with the UT and red groups. Corneal fluorescein staining scores significantly increased in the blue group when compared with UT, red, and green groups at days 5, 7, and 10. A significant increase in the corneal levels of IL-1ß and IL-6 was observed in the blue group, compared with the other groups. The blue group showed significantly increased reactive oxygen species production in the DCF-DA assay and increased inflammatory T cells in the flow cytometry. A significantly increased TUNEL positive cells was identified in the blue group. CONCLUSIONS: Overexposure to blue light with short wavelengths can induce oxidative damage and apoptosis to the cornea, which may manifest as increased ocular surface inflammation and resultant dry eye.

Phototoxic effects of an operating microscope on the ocular surface and tear film.

PURPOSE: We evaluated light exposure-induced dry eye syndrome by investigating the phototoxic effects of an operating microscope on the ocular surface and tear film in rabbits. METHODS: Sixty eyes of 30 rabbits were divided into 3 groups based on the intensity of light exposure received from an operating microscope: Control group, no exposure to light; group A, 40,000-lx intensity for 30 minutes; and group B, 100,000-lx intensity for 30 minutes. To evaluate the potential damage to the ocular surface and tear film, Schirmer tests, rose bengal staining, and conjunctival impression cytology were performed before the light exposure and at 1, 3, and 5 days afterward. In addition, the expression of interleukin 1-beta was analyzed in tear samples. The expression of mucin 5AC was evaluated using immunofluorescence staining, and periodic acid-Schiff staining was conducted on conjunctival tissues. Corneal and conjunctival tissues were observed by means of electron microscopy. RESULTS: Potential damage to the ocular surface and tear film was found in the light-exposed groups as evidenced by decreased aqueous tear production, devitalized corneal and conjunctival epithelial cells, squamous metaplasia of conjunctival epithelial cells, decreased conjunctival goblet cell density, decreased expression of mucin 5AC, ultrastructural cellular damage to corneal and conjunctival tissues, and increased interleukin 1-beta expression in tears. This damage was more noticeable in group B than in group A (P < 0.05). CONCLUSIONS: Light exposure from an operating microscope had phototoxic effects on the ocular surface and tear film in this in vivo experiment. These changes seemed to intensify as the intensity of the light increased. Therefore, excessive light exposure during ophthalmic procedures could be a pathogenic factor in dry eye syndrome after a surgery is performed.

Changes in conjunctival cytology and tear function tests with radioiodine treatment for hyperthyroidism.

OBJECTIVES: Radioiodine (RAI) is used in the treatment of hyperthyroidism and differentiated thyroid cancer. Radioiodine therapy is associated with dry eyes and some side effects are seen especially due to beta rays. In this study, the functional and cytological status of lacrimal glands after RAI therapy was evaluated. METHODS: Twenty-five patients with a mean age of 55.16 years with planned low-dose RAI therapy were evaluated. Just before and 6 months after the treatment, the lacrimal glands were evaluated with tear break-up time (BUT), Schirmer's test, impression cytology and "Ocular Surface Disease Index (OSDI)" questionnaire. RESULTS: The mean value of Schirmer's test was 16.20 ± 3.61 pre-treatment and 11.28 ± 4.39 post-treatment for the right eye, and 15.76 ± 3.27 and 10.60 ± 4.42 for the left eye, respectively. The mean value of Schirmer's test decreased significantly post-treatment in both eyes (p = 0.0001). The BUT score also decreased significantly post-treatment (p = 0.001). The mean value of OSDI score was 27.5 ± 8.02 pre-treatment and 46.36 ± 10.27 post-treatment. The mean value of OSDI score increased post-treatment (p = 0.0001). The impression scores also increased post-treatment in both eyes (p = 0.0001). CONCLUSION: Even low-dose (≤30 mci) RAI treatment affects lacrimal gland functions. Low-dose RAI causes a decrease in the value of Schirmer's test and the BUT test, and an increase in the value of OSDI score and impression scores.

Antioxidant content and ultraviolet absorption characteristics of human tears.

PURPOSE: Dry eye syndrome is a common age-related disorder, and decreased antioxidant/ultraviolet (UV) radiation protection in tears may be part of the cause. This study aimed to compare the tear antioxidant content and flow rate in young and older adults. The total antioxidant content and UV absorbing properties of various commercially available ophthalmic solutions used to alleviate dry eye symptoms were also examined. METHODS: Minimally stimulated tears were collected from 120 healthy Chinese adults with no ocular pathology. Two age groups were studied: 19 to 29 years (n = 58) and 50 to 75 years (n = 62). Tear samples from each subject and 13 ophthalmic solutions were analyzed for total antioxidant content (as the Ferric Reducing/Antioxidant Power value). Tear flow rates were estimated from time taken to collect a fixed volume of tear fluid. UV absorbance spectra of pooled fresh reflex tear fluid and the ophthalmic solutions were determined. RESULTS: Results showed that the antioxidant content of minimally stimulated tears from older subjects (398 ± 160 µmol/l) was not significantly lower than that of younger subjects (348 ± 159 µmol/l; p = 0.0915). However, there was a significant difference in the tear flow rates between the two groups (p < 0.0001), with the younger group having three to four fold higher flow rate. None of the commercial preparations tested had detectable antioxidant content, and none showed the UV absorption characteristics of natural reflex tears. CONCLUSIONS: The effect of low flow rate on the dynamic antioxidant supply to the corneal surface indicates that older subjects have poorer overall defense against photooxidative and other oxidative processes. This could predispose older persons to corneal stress and development of dry eye syndrome. The commercially available artificial tears tested lack both the antioxidant content and UV absorbing characteristics of natural tears. Artificial tears formulations that help restore natural antioxidant and UV absorbing properties to the tear film of the aging eye may help prevent or improve dry eye symptoms and promote ocular health.

A study on photochemical behavior of lysozyme-bromophenol blue complex and its analytical application.

It was found that macromolecular complexes were formed between lysozyme and bromophenol blue (BPB) with the electrostatic attraction in acetate medium (pH 6.5). The binding constant and the number of binding site for lysozyme-BPB complex were obtained, and the thermodynamic parameters were given. In addition, a remarkable enhancement of resonance light scattering (RLS) intensity for the macromolecular complex was observed with a scattering peak at 336 nm. And the increment of RLS intensity was proportional to the concentration of lysozyme in the range of 5 ng ml(-1) to 10.0 microg ml(-1). The influence of experimental conditions including pH, BPB concentration, and ionic strength on RLS system were tested, especially the effect of temperature was examined in detail. The proposed method was successfully applied to determine lysozyme in human saliva and tear samples without any special pretreatment. Compared with other methods the proposed method is of higher sensitivity and wider linear range.

Effects of inhibition of urokinase-type plasminogen activator (u-PA) by amiloride in the cornea and tear fluid of eyes irradiated with UVB.

The purpose of the present study was to test our hypothesis that amiloride, a specific u-PA inhibitor, effectively decreases u-PA activity in cornea as well as in tear fluid and favourably affects corneal healing. Therefore, comparative histochemical and biochemical studies of u-PA and the effects of amiloride were performed on rabbit corneas and tear fluid using the sensitive fluorogenic substrate Z-Gly-Gly-Arg-7-amino-4-trifluoromethylcoumarin. Rabbit eyes were repeatedly irradiated with UVB for 9 days and during the irradiation topically treated with amiloride (1 mg/ml saline) or placebo (saline) (dropwise, 5 times daily). Results show that in placebo-treated eyes, UVB evoked the appearance of u-PA activity in cornea and tear fluid in early stages of irradiation, and u-PA levels increased during irradiation. Corneal epithelium was gradually lost and remnants of the epithelium as well as keratocytes in the upper part of corneal stroma showed high u-PA activity. Finally, corneas lost their epithelium completely. In corneal stroma, numerous u-PA-containing inflammatory cells were present. Corneas were vascularized. When amiloride was dropped on the eye surface on the first day of irradiation and subsequently daily until the end of the experiment, u-PA activity in both cornea and tear fluid was strongly inhibited. Corneas were covered with a continuous epithelium until the end of the experiment. The number of inflammatory cells was significantly decreased. Corneal vascularization was reduced by 50%. In conclusion, early application of amiloride inhibited u-PA activity in UVB-irradiated corneas as well as in tear fluid and diminished the development of corneal pathology.

Ocular surface changes and tear film alterations associated with sun gazing during a solar eclipse.

PURPOSE: A solar eclipse occurred in central Europe on August 11th, 1999. Following the eclipse, patients with ocular symptoms were investigated. Gazing at the sun without protection is liable to damage the retina. Our attention was focused on changes of the ocular surface and the tear film. METHODS: Forty-three patients were investigated within one week after the solar eclipse as baseline. 33 of them were followed up one year later. Visual acuity and the central visual-field were measured, and the ocular surface and the fundus were examined using a slit lamp. The quality of the lacrimal tear film was examined using Schirmer's test for the aqueous layer, break-up time for the mucous layer and interference observation for the lipid layer, measured by a slit lamp and a tearoscope. RESULTS: At the baseline 19 patients had non-specific visual problems. Pathological alterations of the tear film were seen in all three tear-film layers: Schirmer's test was pathological in 87%, break-up time decreased in 85%, the interference pattern of the lipid layer changed in 67% and there were changes in 87% using the tearoscope. One year later the non specific visual disorders had disappeared. Schirmer's test did not reveal much change from the baseline: 51% pathological, 24% remained pathological in break-up-time and the lipid layer was normalized except in 9%. Using the tearoscope, lipids were better than grade 3 in all patients. CONCLUSION: After gazing at a solar eclipse the ocular surface and tear film changed. While the aqueous layer remained pathological in many patients, the lipid layer and the mucous layer recovered spontaneously.

The appearance of active plasminogen activator of urokinase type (u-PA) in the rabbit anterior eye segment irradiated by UVB rays. A histochemical and biochemical study.

Repeated irradiation of the rabbit eye with UV rays of 312 nm wavelength (UVB) evoked the appearance of active plasminogen activator of urokinase type (u-PA) in the anterior eye segment. Using histochemistry, active u-PA appeared first in the corneal epithelium followed by the corneal endothelium, inflammatory cells in the corneal stroma and the lens epithelium. With a semiquantitative fluorescent method active u-PA was also found in the tear fluid and aqueous humour. UV rays of 365 nm wavelength (UVA) under the same conditions did not cause the appearance of active u-PA in the anterior eye segment.

Do human tears absorb ultraviolet light?

We analyzed human tears by ultraviolet (UV) spectrophotometry for transmittance of UV light. Ultraviolet light was readily transmitted through human tears in the UV-A (320-400 nm) and UV-B (290-320 nm) ranges. Tears partially absorbed UV light in the UV-C (100-290 nm) range. The clinical implications of these findings include prevention of phototoxic ocular damage and effects upon excimer laser corneal photoablative techniques.

Quantification of lacrimal function after D-shaped field irradiation for retinoblastoma.

To study the quantitative effects of megavoltage external beam irradiation in a D-shaped field in patients with retinoblastoma, biomicroscopy was performed in 61 patients and tear function tests (Schirmer-lactoferrin and lysozyme tests) on 45 eyes in 34 irradiated patients. The results were compared with those obtained in 25 non-irradiated control eyes. The Schirmer test was significantly diminished (p < 0.001) in irradiated eyes, as were the lactoferrin and lysozyme values (p < 0.001). A mild to severe keratitis was found in 17 of the 61 patients (28%). A significant correlation (p < 0.005) was found between the severe keratitis and the mean Schirmer values; the mean lactoferrin and lysozyme values were diminished in all patients but did not correlate significantly with the corneal abnormalities. These quantitative data, obtained in patients treated for retinoblastoma, affirm the qualitative data found in patients irradiated for other reasons such as orbital or sinus tumours. Irradiation for retinoblastoma is not a harmless treatment and serious late side effects have to be considered.