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A New, Specular Reflection-Based, Precorneal Tear Film Stability Measurement Technique in a Rabbit Model: Viscoelastic Increases Tear Film Stability
摘要： PURPOSE. To develop a safe, noninvasive, noncontact, continuous in vivo method to measure the dehydration rate of the precorneal tear film and to compare the effectiveness of a viscoelastic agent in maintaining the precorneal tear film to that of a balanced salt solution. METHODS. Software was designed to analyze the corneal reflection produced by the operating microscope’s coaxial illumination. The software characterized the shape of the reflection, which became distorted as the precorneal tear film evaporated; characterization was accomplished by fitting an ellipse to the reflection and measuring its projected surface area. Balanced salt solution Plus (BSS+) and a 2% hydroxypropylmethylcellulose viscoelastic were used as the test agents. The tear film evaporation rate was characterized and compared over a period of 20 minutes in 20 eyes from 10 New Zealand white rabbits. RESULTS. The ellipse axes ratio and surface area were found to decrease initially after each application of either viscoelastic or BSS+ and then to increase linearly as the tear film began to evaporate (P < 0.001) for eyes treated with BSS+ only. Eyes treated with BSS+ required 7.5 ± 2.7 applications to maintain sufficient corneal hydration during the 20-minute test period, whereas eyes treated with viscoelastic required 1.4 ± 0.5 applications. The rates of evaporation differed significantly (P < 0.043) between viscoelastic and BSS+. CONCLUSIONS. The shape and surface area of the corneal reflection are strongly correlated with the state of the tear film. Rabbits’ corneas treated with viscoelastic remained hydrated significantly longer than corneas treated with BSS+.
关键词： evaporation,corneal hydration,precorneal tear film stability,viscoelastic,balanced salt solution
更新于2025-09-23 15:22:29
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Agreement of non-invasive tear break up time measurement between Tomey RT-7000 Auto Refractor-Keratometer and Oculus Keratograph 5M
摘要： Background: It is difficult to standardize assessment of dry eye in different clinical settings. Increasingly, tear stability is recognized to be important for the definition and assessment of patients with dry eye. Recently, two commercially available instruments have been made available for objectively measuring noninvasive tear break-up time (NIBUT), as an indicator of tear stability: the Tomey RT-7000 Auto Refractor-Keratometer and Oculus Keratograph (K)5M. We aim to assess the agreement of NIBUT measurements using these modalities. Methods: This prospective cross-sectional study was carried out in a tertiary referral eye center and involved 126 consecutive dry eye patients. NIBUT assessment was performed on the right eyes of participants with both the RT-7000 and the K5M techniques, with the order of assessment randomized. The Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaires were administered to assess dry eye symptoms in the 2 weeks before assessment. Results: The age of the participants was 56.0±14.3 years (69.84% females). Measurements for both modalities were non-normally distributed (right-skewed). The median RT-7000 and K5M readings were 4.2 (range 0.1–10.0) and 6.4 (0.1–24.9) seconds, respectively. RT-7000 and K5M readings were poorly correlated (ρ=0.061, P=0.495). Intraclass correlation coefficient between the modalities was 0.187 (95% confidence interval -0.097 to 0.406). The Bland–Altman plot showed no systematic differences between the readings with these machines. The agreement between machines was not different in different SPEED categories. Conclusion: While there are theoretical and practical benefits of NIBUT for assessment of tear stability over dye-based methods, the agreement between the two modalities was poor. Hence, studies and trials assessing NIBUT should avoid using these modalities interchangeably for NIBUT assessment. More research is needed to improve consensus on how to determine NIBUT.
关键词： tear film,tear break-up time,Tomey RT-7000,dry eye,Oculus Keratograph
更新于2025-09-23 15:21:01
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Randomised double-masked placebo-controlled trial of the cumulative treatment efficacy profile of intense pulsed light therapy for meibomian gland dysfunction
摘要： Purpose: To assess long-term cumulative treatment effects of intense pulsed light (IPL) therapy in meibomian gland dysfunction (MGD). Methods: Eighty-seven symptomatic participants (58 female, mean±SD age, 53±16 years) with clinical signs of MGD were enrolled in a prospective, double-masked, parallel-group, randomised, placebo-controlled trial. Participants were randomised to receive either four or five homogeneously sequenced light pulses or placebo treatment to both eyes, (E-Eye Intense Regulated Pulsed Light, E-Swin, France). Visual acuity, dry eye symptomology, tear film parameters, and ocular surface characteristics were assessed immediately before treatment on days 0, 15, 45, 75, and four weeks after treatment course completion on day 105. Inflammatory and goblet cell function marker expression, and eyelid swab microbiology cultures were evaluated at baseline and day 105. Results: Significant decreases in OSDI, SPEED, and SANDE symptomology scores, and meibomian gland capping, accompanied by increased tear film lipid layer thickness, and inhibited Corynebacterium macginleyi growth were observed in both treatment groups (all p<0.05). Sustained clinical improvements occurred in both treatment groups from day 75, although significant changes from day 45, in lipid layer quality, meibomian gland capping, OSDI and SANDE symptomology, were limited to the five-flash group (all p<0.05). Conclusions: IPL therapy effected significant improvements in dry eye symptomology, tear film lipid layer thickness, and meibomian gland capping in MGD patients. Five-flash IPL treatment showed superior clinical efficacy to four-flash, and an initial course of at least four treatments is suggested to allow for establishment of sustained cumulative therapeutic benefits prior to evaluation of overall treatment efficacy.
关键词： lipid layer,Intense pulsed light,ocular surface,dry eye,tear film,meibomian gland
更新于2025-09-16 10:30:52
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Clinical results of Intraductal Meibomian gland probing combined with intense pulsed light in treating patients with refractory obstructive Meibomian gland dysfunction: a randomized controlled trial
摘要： Background: This study aims to optimize the therapeutic regimen for refractory obstructive meibomian gland dysfunction (o-MGD) patients by combining intraductal meibomian gland probing (MGP) and intense pulsed light (IPL) to enhance their positive effects and reduce their limitations. Methods: This randomized, assessor blind study includes 45 patients (90 eyes) with refractory o-MGD who were divided into 3 groups via allocation concealment: IPL (group I, received an IPL treatment course: 3 times at 3-week intervals), MGP (group II, received MGP one time), and combined MGP-IPL (group III, MGP first followed by an IPL treatment course). Standard Patient Evaluation of Eye Dryness score (SPEED), tear break-up time (TBUT), corneal fluorescein staining (CFS), meibum grade, and lid margin finding results were assessed at baseline, 3 weeks after final treatment for groups I and III, 3 and 12 weeks after MGP for group II. Six months after final treatment, the SPEED and willingness to receive any treatment again were also collected for all groups. Paired Wilcoxon, Mann-Whitney U with Bonferroni correction, and Kruskal-Wallis tests were used for data analysis. Results: For all 3 groups, all previously mentioned indexes improved significantly following treatment (P<0.01). MGP-IPL was better than IPL and MGP in terms of post-treatment SPEED, TBUT, meibum grade, and lid telangiectasia (P<0.05/3). Furthermore, the MGP-IPL was better than IPL in terms of lid tenderness and better than MGP in terms of orifice abnormality (P< 0.05/3). Six months later, the SPEED for the MGP-IPL was also significantly lower than other groups (P<0.05/3). Moreover, no patients in the MGP-IPL group expressed the need to be treated again compared to 35.7% or 20% of patients in the IPL or MGP groups, respectively. Conclusions: Compared with IPL or MGP alone, the combination MGP-IPL produced best results in relieving all signs and symptoms and helping patients attain long-lasting symptom relief.
关键词： Intraductal meibomian gland probing,Tear film,Intense pulsed light,Obstructive meibomian gland dysfunction,Meibum
更新于2025-09-11 14:15:04
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Functional Visual Acuity
摘要： Dry eye (DE) causes irregularity of the ocular surface and reduces the quality of vision. An intact, regular tear ?lm is essential for high-quality retinal images; however, visual tasks requiring sustained gazing can disrupt the tear ?lm, eventually degrading visual function. A functional visual acuity (FVA) measurement system has been uniquely developed in Japan to evaluate visual function related to tear stability in patients with DE. FVA has been shown to correlate with optical quality. The system measures the change in visual acuity (VA) over time automatically in aqueous-de?cient DE and short tear breakup tear ?lm DE characterized by decreased tear stability and minimal epithelial damage. It is also useful to detect minimal visual deterioration correlated with minimal ocular surface abnormality and vision-related quality of life otherwise undetectable by conventional VA testing, to assess and quantify vision-related symptomatology, and to determine the ef?cacy of treatments for DE disease. Recently, its use has been expanded, such as for the analysis of visual function accompanying lens, cataract and cataract-related disease, retinal disease, refractive surgery, contact glaucoma, amblyopia, presbyopia, and vehicle driving. Its use has revealed that FVA re?ects not only visual function related to tear dynamics, but also visual function related to quick recognition of the target. This simple, noninvasive, and sensitive FVA measurement system may be expected to be used worldwide.
关键词： tear film,visual function,dry eye,functional visual acuity,tear breakup time
更新于2025-09-09 09:28:46
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Characterization of the thickness of the tear film lipid layer using high resolution microscopy
摘要： Interferometry is an optical technique that have been used to quantify the lipid layer of the precorneal tear film, and to investigate the relationship between lipid layer thickness and tear film evaporation. However, the relationship between lipid layer thickness and the rate of evaporation is far from consistent. One possible reason is the inherent limit of contemporary interferometric systems, which employ objectives with relatively long depth of focus (DOF) (>15 μm or more), which tend to collect excessive extra-planar noise. This limitation may negatively affect the accuracy of the characterization and thickness measurement of the lipid layer. The current system incorporated an objective with limited DOF (~1.5 μm) into a custom-built optical microscope to image the tear film lipid layer in humans. An algorithm was also developed to process these images. One major outcome of this system is that thick lipid layers exhibit higher variation in thickness values than thin or normal-thickness lipid layers. The variations may reflect the structural differences of the lipid layer, which may offer a novel dimension to explain the missing correlation between lipid layer thickness and evaporation. In summary, the development of the high resolution microscopy system and associated data processing algorithm may provide new insights into the lipid layer structure, topography and their relation to the tear film evaporation rate.
关键词： tear film,dry eye,interferometry,lipid layer thickness
更新于2025-09-04 15:30:14