Local synthesis of sex hormones:are there consequences for the ocular surface and dry eye?

Sex hormones are associated with the physiology and pathophysiology of almost all organs in the body, as well as most diseases. Interest in the associations between sex hormones and ocular tissues has increased in recent years. Androgens may have a positive effect on dry eye, whereas the effects of oestrogen on ocular conditions remain unclear. Intracrinology, the local synthesis and metabolism of hormones that is unique to humans, is of relevance to the eye and may help to explain why studies of the relationship between oestrogens and dry eye signs and symptoms are inconclusive. Knowledge of the pathways of hormone formation and metabolism is crucial to understanding the pathogenesis of ocular disease including dry eye. This review examines the mechanisms of steroidal sex hormone biosynthesis and reviews the significance of locally produced sex hormones, with a focus on ocular surface tissues. Much of the current literature is based on animal studies, which may not be transferable to humans due to the absence of intracrine production in animals. A large proportion of the human studies investigate systemic hormone levels rather than local levels. There is subsequently a need for additional studies to provide a better understanding of the local production of sex hormones within the human eye and ocular surface and to clarify the relationships between ocular levels of sex hormones and conditions including dry eye

Mapping the Corneal Sub-Basal Nerve Plexus in Orthokeratology Lens Wear Using in vivo Laser Scanning Confocal Microscopy

PURPOSE. This study was designed to map the sub-basal nerve plexus (SBNP) in the cornea of orthokeratology (OK) lens wearers. METHODS. Laser scanning confocal microscopy (LSCM) was performed in vivo on three subjects: a non-lens wearer and two OK lens wearers. Scans were performed on the right eye while the left eye fixated a moving target. A total of 575, 430, and 676 contiguous images of the SBNP were taken from the non-lens wearing and the OK lens wearing subjects, respectively, and used to construct maps of the central to midperipheral SBNP. RESULTS. In the non-lens wearing eye, nerves radiated towards a whorl-like complex centered nasally and inferiorly in an overall pattern consistent with previously reported studies. In the OK lens wearing eyes, this whorl pattern was absent, replaced by a tortuous network of nerve fibers centrally, and thicker curvilinear fibers mid-peripherally, particularly in the nasal, inferior, and temporal regions. CONCLUSIONS. This study maps the corneal SBNP in OK lens wearers and provides compelling evidence that OK lens wear alters the normal SBNP distribution observed in healthy, nonlens wearing eyes. (Invest Ophthalmol Vis Sci

Biophysical characteristics of the tear film in school-aged children

Purpose : The ocular surface and tear film in children are not as well characterised as in adults. Biophysical properties of tears are associated with their ability to spread on the ocular surface and reduce surface tension to form a stable tear film. The aim of this study was to investigate biophysical properties of tears in school-aged children and examine the relationship with age. Methods : Unstimulated tears were collected from 21 healthy children (age 6-14 years, 71% female) using glass capillary tubes. For each participant, tears were spread on the surface of an artificial tear solution reflecting the salt composition of tears and maintained at the physiological pH (7.4) and temperature (35°C) in a Langmuir trough. The tear film was compressed and expanded with two barriers and surface pressure was continually recorded with a pressure sensor to give pressure-area profiles. Pressure-area profiles were qualitatively compared between all participant tear samples. Maximum surface pressure at the highest compression for each participant sample was determined from profiles. Associations between maximum surface pressure and age were examined using Pearson correlation, and male and female samples were compared using Mann-Whitney U test. Profiles were also compared with a representative historical adult tear sample (35 y, female, normal ocular surface). Results : Pressure-area profiles of tear films of all participants indicated features of a stable, highly compressible liquid film with continuous increase in pressure without any collapse of the film. Profiles of child participants were similar and comparable to the profile of the historical adult sample. Group mean maximum surface pressure at the highest compression for child participants was 33 ± 3.5 mN/m. There were no significant relationships between maximum surface pressure and age (p=0.8) or sex (p=0.7). Conclusions : Biophysical characteristics of tears in school-aged children are comparable with adult tears and are not affected by age or sex. Many components including lipids and proteins contribute to the surface pressure of tears. Surface pressure of adult tears is known to be higher than surface pressure of lipid component alone because of additional contribution from proteins. Future investigations will examine the contribution of different components in children’s tears to overall tear stability

Dry eye signs and symptoms in aromatase inhibitor treatment and the relationship with pain

Purpose: Aromatase inhibitors (AIs) limit the synthesis of oestrogen in peripheral tissues thus lowering levels of oestrogen. The primary aim was to evaluate whether women treated with AIs have altered dry eye symptoms and signs. A sub-aim was to investigate whether symptoms of dry eye in postmenopausal women were associated with symptoms of non-eye pain, ocular pain and self-rated pain perception.  Methods: This cross-sectional, observational, single visit study recruited 56 postmenopausal women (mean age 64.1 + 7.9 years) and 52 undergoing AI treatment (mean age 66.6 + 9.0). Ocular symptoms (OSDI, MGD14) and pain questionnaires (PSQ, OPAS) were administered and signs of dry eye and meibomian gland dysfunction were evaluated.  Results: Almost half of each group reported dry eye symptoms, defined as OSDI>12 (48% control, 46% AI). The PSQ score was significantly higher in the AI group (p = 0.04). Neither frequency or severity of dry eye (or MGD) symptoms scores were significantly different between groups. In the AI group, meibomian gland expressibility score was worse (p = 0.003); there were no differences in any other signs. Higher OSDI scores were associated with higher OPAS eye-pain scores (r = 0.49, p < 0.001), but not OPAS non-eye pain (r = 0.09, p = 0.35). Pain perception (PSQ) showed a moderate positive association with OPAS eye-pain (r = 0.30, p = 0.003).  Conclusions: In this study elevated ocular symptoms were observed in both the AI treated and the untreated groups, with no difference between the groups. Women undergoing AI treatment for early stage breast cancer had worse meibum expressibility score and increased pain perception compared to an untreated group of women

Ocular surface sensitivity repeatability with cochet-bonnet aesthesiometer

Purpose. To determine the repeatability of ocular surface threshold measurements using the Cochet-Bonnet esthesiometer on the same day and 3 months apart. Methods. Two separate studies were conducted to determine the repeatability of ocular surface threshold measurements made on the same day (n = 20 subjects) and 3 months apart (n = 29 subjects). The Cochet-Bonnet esthesiometer was used to measure corneal and inferior conjunctival thresholds using the ascending method of limits. The pressure exerted by the Cochet-Bonnet esthesiometer was determined using an analytical balance, for both the 0.08- and 0.12-mm-diameter filaments. This calibration was then used to convert filament length measurements to pressure. Repeatability was determined using a Bland and Altman analysis. Results. The pressure exerted at each filament length differed between the two filament diameters. The measured pressure also differed from values provided by the manufacturer. Repeatability of threshold measurements at the central cornea was shown to be good, with better repeatability for same-day measurements (coefficient of repeatability [CoR] = T0.23 g/mm2) than for those 3 months apart (CoR = T0.52 g/mm2). Threshold measurements at the inferior conjunctiva, in contrast, were poorly repeatable (CoR = T12.78 g/mm2). Conclusions. Cochet-Bonnet esthesiometry is repeatable when performed on the central cornea on the same day and 3 months apart, but this instrument is not recommended for conjunctival threshold measurements. (Optom Vis Sci 2015;92:183Y189) Key Words: Cochet-Bonnet esthesiometer, repeatability, ocular surface sensitivity, corneal mechanical threshold, conjunctival mechanical threshol

A Possible Association between Dry Eye Symptoms and Body Fat:A Prospective, Cross-Sectional Preliminary Study

Objectives: To examine the relationship between dry eye symptoms and adiposity in a population study. Methods: A prospective cross-sectional single-visit preliminary study was designed to sample ocular symptoms and indices of adiposity in the general adult population. Patients recruited from the UNSW optometry clinic, the university campus and surrounding community, and overseas were invited to complete a survey composed of the short form Dry Eye Questionnaire (SFDEQ) (Dry Eye Questionnaire-5 or Contact Lens Dry Eye Questionnaire-8) and the Ocular Comfort Index (OCI) via hardcopy or online. Participants self-measured their weight, height, waist circumference (WC), and body fat % (optional). Associations between measures of adiposity (Body mass index [BMI], WC, and body fat %) and ocular symptoms scores (SFDEQ and OCI) were determined using Spearman correlation coefficients. Group differences were compared using independent t test. Results: Three hundred and five participants including 52 contact lens wearers completed the study and 78 of them measured body fat %. There was a moderate correlation between body fat % and dry eye symptoms (SFDEQ r=0.34, P=0.003; OCI r=0.32, P=0.004). The interaction between body fat % and gender, wear of contact lenses, and older age were shown to be significant predictors of less ocular comfort in multivariate analysis (F (3,74) =12.13, P&lt;0.001). Conclusions: An association between adiposity measured by body fat % and symptoms of dry eye was demonstrated in the general adult population. Confirmation of these findings in a large study is required.</p