In Vivo Human Lacrimal Gland Imaging Using an Ultrasound Biomicroscopy.

PURPOSE: In the present study, we introduce human lacrimal gland imaging using an ultrasound biomicroscopy (UBM) with a soft cover and show their findings. METHODS: The representative UBM findings of palpebral lobes in seven subjects (four with non-Sjögren dry eye syndrome, one with Sjögren syndrome, and two healthy subjects) were described in this study. To prolapse the palpebral lobe, the examiner pulled the temporal part of the upper eyelid in the superotemporal direction and directed the subject to look in the inferonasal direction. We scanned the palpebral lobes longitudinally and transversely using UBM. We used an Aviso UBM with a 50 MHz linear probe and ClearScan. RESULTS: In UBM of two healthy subjects, the echogenicity of the lacrimal gland was lower than that of the sclera and homogeneous. But the parenchyma of a patient with Sjögren dry eye syndrome was quite inhomogeneous compared to the healthy subjects. In two patients with dry eye syndrome, we were able to observe some lobules in the parenchyma. We could find excretory ducts running parallel at the surface of the longitudinal section in some subjects. In the longitudinal UBM scan of a subject, we observed a tubular structure at a depth of 1,500 µm that was considered a blood vessel. It ran from the superonasal to the inferotemporal direction. In a subject, we observed a large cyst beneath the conjunctiva. CONCLUSIONS: Lacrimal gland imaging using UBM has both advantages of optical coherence tomography and sonography, and could be useful for evaluating dry eye syndrome.

Association of Meibomian Gland Dysfunction with Oral Statin Use.

This retrospective cross-sectional study aimed to determine the association of oral statin use, dry eye disease (DED), and meibomian gland dysfunction (MGD). A total of 93 subjects were included and divided into two groups: statin users (n = 45) and nonstatin users (n = 47). Significant differences were observed in the total cholesterol (p = 0.013), low-density lipoprotein (LDL) (p = 0.005), and meiboscore (p = 0.000) levels between the two groups. For stratified analysis, the statin group was divided into subgroups according to the type or dose of statin and total duration of statin use. However, there were no differences in clinical features between the subgroups. In multiple regression analysis, meiboscore was significantly associated with age (slope = 0.05, p = 0.00) and statin use (slope = -1.19, p = 0.00), with an R2 of 0.44. Thus, older adults and participants who do not use statin appeared to have higher scores. In conclusion, although the mechanism is unclear, statins may exert a protective effect on the meibomian gland. Further lipidomic studies are required to determine the pharmacological effects of statins on the meibomian gland and other meibum components.

Association of Serum Lipid Level with Meibum Biosynthesis and Meibomian Gland Dysfunction: A Review.

The primary role of meibomian glands (MGs) is to actively synthesize and secret lipids and proteins spread onto the tear film, and the glandular lipids promote tear stability, prevent evaporation, and reduce friction. Meibomian gland dysfunction (MGD) is the leading cause of dry eye disease and one of the most common ophthalmic problems worldwide. MGs are densely innervated and regulated by hormones and growth factors. However, since the polar and nonpolar lipids are produced through processes in MGs that are not completely understood, a relevant question has been raised: Would the altered systemic lipids metabolism affect the physiology and structure of MGs? This review introduces the recent update regarding the relationships between serum lipid and MGD in clinical and basic research while providing answers to this question. A causal relationship remains to be established; however, serum lipid level or dyslipidemia may be related to MGD directly or indirectly, or both. Further studies are warranted to establish the role of serum lipid level and meibocyte differentiation/maturation and lipid synthesis.

A new noncontact tonometer using corneal photoelasticity: porcine eye study.

PURPOSE: To propose a new noncontact tonometer based on corneal photoelasticity. METHOD: In this study, we experimented with 18 enucleated porcine eyes. The anterior chamber was infused with a physiological solution. A circular polarizing filter was attached to an ophthalmic surgical microscope. Color fringe changes at the peripheral cornea related to its photoelasticity were recorded using an ophthalmic surgical microscope equipped with a charge-coupled device camera while intraocular pressure (IOP) changes were determined by the height of the physiological solution bottle. A peak intensity of the color fringes was determined by Image J software. RESULTS: Circular, rainbow-like color fringes, a phenomenon that is the basis of photoelasticity, were detected in the peripheral cornea. When IOP increased from 7 to 29 mm Hg, the color fringes moved more peripherally becoming narrower with their peak intensity increasing. At an IOP of 7, 15, 22 and 29 mm Hg, the mean peak intensity of the color fringes had a gray value of 113.6, 114.2, 114.7 and 115.5, respectively. Correlation analysis between IOP and peak intensity of the color fringes in these porcine eyes showed a significant positive correlation with a Pearson correlation coefficient of 0.993 (p < 0.01). CONCLUSIONS: The proposed noncontact tonometer based on photoelasticity of the cornea could become a true noncontact device that could be used for the screening of glaucoma or as an IOP follow-up for glaucoma patients.

Relationships between keratometry and collagen fibrillar structure of cornea by circular polarization biomicroscopy.

PURPOSE: To evaluate the relationships between keratometry and collagen fibrillar structure of cornea by circular polarization biomicroscopy. METHODS: Thirty-four subjects (63 eyes) were included in this study. Intraocular pressure (IOP) was measured, and keratometry was done with an automated keratometer. When the corneal astigmatism was larger than 0.75 diopter, corneal topography was done. After pupil dilation, the examiner placed a circular polarizing filter in front of the subject's eye. The images were captured by a camera connected to the slit lamp. Interfocal distance and angle were measured with ImageJ. The correlations between corneal astigmatism and interfocal distance-angle were examined by double angle vector diagram. Scalar analyses were done for the correlations between subject age and interfocal distance, between IOP and interfocal distance, and between mean cornea power and interfocal distance. RESULTS: The mean age of the 34 subjects was 59 ± 16 years. Mean interfocal distances and angles determined by double angle vector diagram were 4.67 mm and -20.5 degrees in the right eye and 3.73 mm and +24.2 degrees in the left eye. The correlation between age and interfocal distance and between IOP and interfocal distance were statistically insignificant (P = 0.913 and 0.361, respectively). The interfocal distance and angle showed no statistically significant correlation with corneal astigmatism by vector analysis (P = 0.221 and 0.850, respectively). The fibrillar structure pattern in circular polarizing biomicroscopy showed no statistically significant relationship with the bow tie pattern in corneal topography (P = 0.762). However, analysis of the correlation between mean corneal power and interfocal distance showed a statistically significant, but weak positive correlation (r = 0.326, P = 0.019). CONCLUSIONS: Interfocal distance determined through circular polarizing biomicroscopy showed a positive correlation with mean corneal power. But age, IOP, and corneal astigmatism did not show a significant correlation with interfocal distance and angle.

Endothelial damage of a donor cornea depending on the donor insertion method during Descemet-stripping automated endothelial keratoplasty in porcine eyes.

PURPOSE: To compare endothelial damage of the donor cornea in relation to the method of inserting the donor cornea into the recipient anterior chamber during Descemet-stripping automated endothelial keratoplasty (DSAEK). METHODS: Fifteen enucleated pig eyes were used. The donor corneoscleral buttons were mounted in an artificial anterior chamber. The anterior lamella was excised using a microkeratome and punched using a trephine. The following methods were employed to insert the donor cornea into the recipient anterior chamber: (1) The donor was folded over, grasped using forceps, and inserted ("taco" technique). (2) The forceps were inserted and the edge of the donor was grasped and dragged into the chamber. (3) A loop was made at the edge of the donor by suturing with nylon. A hook was inserted to drag the donor by the loop into the chamber. After insertion, the incision on the recipient eye was extended, and the donor cornea was removed for examination. After vital staining, the samples were examined under a light microscope and a scanning electron microscope. RESULTS: With the taco technique, endothelial damage (17.9%) was observed in areas where the forceps held the donor. In the drag technique using forceps, endothelial damage (17.3%) was observed where the forceps made contact and in the folds in this area. In the drag technique using a suture, endothelial damage (18.8%) was observed in the area of the needle puncture and in folds in this area. CONCLUSION: The amount of endothelial damage did not differ significantly among the three different methods of donor insertion during DSAEK in this animal model, but each method exhibited a different endothelial damage pattern.