Ocular Impression-Taking-Which Material Is Best?

OBJECTIVES: To assess the efficacy and effect on clinical signs of a polyvinylsiloxane (Tresident; Shütz Dental Group GmbH, Germany) compared with an irreversible hydrocolloid (Orthoprint; Zhermack SpA, Badia Polesine, Italy) for ocular impression-taking. METHODS: Twenty subjects were recruited (13 female and 7 male), with mean age 31.1±4.6 years (SD) (range 25.8-39.7). Subjects attended for 2 sessions, each of 1-hr duration, on 2 separate days. Each session was scheduled at the same time on each day. At each visit, the subject underwent an ocular impression procedure, using either Tresident or Orthoprint, in random order and to one eye only. Investigator 2 was blind to this assignment. Two experienced practitioners conducted the study, investigator 1 performed the ocular impression procedures and investigator 2 observed and assessed the clinical signs: logMAR visual acuity, ocular surface staining, tear break-up time (TBUT), and ocular hyperemia. RESULTS: Visual acuity was unaffected by either material; TBUT was marginally disrupted by both materials, but was not clinically significant according to published criteria; ocular redness increased with both materials; and corneal staining was significantly greater after Orthoprint impression. Less redness and clinically insignificant staining after impression-taking, with fewer clinical complications, was found after use of Tresident. CONCLUSIONS: Tresident offers a quicker, more effective, and clinically viable method of obtaining ocular impression topography compared with the traditional Orthoprint, and Orthoprint causes significantly more superficial punctuate staining of the corneal epithelium than Tresident.

Budget impact model of Mydrane®, a new intracameral injectable used for intra-operative mydriasis, from a UK hospital perspective.

BACKGROUND: During cataract surgery, maintaining an adequate degree of mydriasis throughout the entire operation is critical to allow for visualisation of the capsulorhexis and the crystalline lens. Good anaesthesia is also essential for safe intraocular surgery. Mydrane® is a new injectable intracameral solution containing two mydriatics (tropicamide 0.02% and phenylephrine 0.31%) and one anaesthetic (lidocaine 1%) that was developed as an alternative to the conventional topical pre-operative mydriatics used in cataract surgery. This study aimed to estimate the budget impact across a one year time frame using Mydrane® instead of topical dilating eye drops, for a UK hospital performing 3,000 cataract operations a year. METHODS: A budget impact model (BIM) was developed to compare the economic outcomes associated with the use of Mydrane® versus topical drops (tropicamide 0.5% and phenylephrine 10%) in patients undergoing cataract surgery in a UK hospital. The outcomes of interest included costs and resource use (e.g. clinician time, mydriasis failures, operating room time, number of patients per vial of therapy etc.) associated with management of mydriasis in patients undergoing cataract surgery. All model inputs considered the UK hospital perspective without social or geographical variables. Deterministic sensitivity analyses were also performed to assess the model uncertainty. RESULTS: Introduction of Mydrane® is associated with a cost saving of £6,251 over 3,000 cataract surgeries in one year. The acquisition costs of the Mydrane® (£18,000 by year vs. £3,330 for eye drops) were balanced by substantial reductions in mainly nurses' costs and time, plus a smaller contribution from savings in surgeons' costs (£20,511) and lower costs associated with auxiliary dilation (£410 due to avoidance of additional dilation methods). Results of the sensitivity analyses confirmed the robustness of the model to the variation of inputs. Except for the duration of one session of eye drop instillation and the cost of Mydrane®, Mydrane® achieved an incremental cost gain compared to tropicamide/phenylephrine eye drops. CONCLUSIONS: Despite a higher acquisition cost of Mydrane®, the budget impact of Mydrane® on hospital budgets is neutral. Mydrane® offers a promising alternative to traditional regimes using eye drops, allowing for a better patient flow and optimisation of the surgery schedule with neutral budget impact.

Relationship between Corneal Sensation, Blinking, and Tear Film Quality.

PURPOSE: To examine the possible role of corneal sensitivity and tear film quality in triggering a blink by investigating the relationship between blink rate, central corneal sensitivity threshold (CST), ocular surface temperature (OST), tear meniscus height (TMH), tear film quality (noninvasive tear break-up time [NIBUT]), and tear film lipid pattern under normal conditions. METHODS: Forty-two volunteers (average age, 27.76 ± 5.36 years; 11 males) with good ocular health (Ocular Surface Disease Index, <15.0) were recruited for this cross-sectional cohort study. Blink rate, CST (noncontact corneal air gas aesthesiometry, NCCA), minimum and maximum OST in the central and inferior cornea between blinks (thermal infrared camera), TMH, NIBUT, and lipid pattern of the tear film (Keeler Tearscope Plus) were recorded on the right eye only. RESULTS: Median blink rate was 11 blinks/min (interquartile range [IR], 6.95 to 17.05), CST was 0.35 mbars (IR, 0.30 to 0.40), minimum OST in the central cornea was 35.15°C (IR, 34.58 to 35.50), and NIBUT was 34.55 s (IR, 12.45 to 53.80). Moderate but statistically significant correlations were observed between CST and NIBUT (r = 0.535, p < 0.001), CST and blink rate (r = -0.398, p < 0.001), lipid pattern and OST (r = 0.556, p < 0.001), and between CST and OST (r = 0.371, p = 0.008). The correlations between blink rate and NIBUT (r = -0.696, p < 0.001) and between OST and NIBUT (r = 0.639, p < 0.001; Spearman test) achieved higher significance; this was highlighted by the linear regression model where NIBUT and minimum central and inferior OST were identified as significant predictor variables. CONCLUSIONS: There is strong evidence for significant interactions between corneal sensitivity, NIBUT, OST, and blink frequency, emphasizing that ocular surface conditions represent a possible important trigger for the initiation of a blink. However, the mechanisms involved in the initiation of a blink are complex, with local ocular sensory input as only one trigger, along with other external influences and internal factors under cortical control.

Comparing self-reported optometric dry eye clinical practices in Australia and the United Kingdom: is there scope for practice improvement?

PURPOSE: The aim of this study was to compare the self-reported clinical practice behaviours of optometrists in Australia and the United Kingdom (UK) with respect to the diagnosis and management of dry eye disease (DED). We also sought to examine whether the reported practices of clinicians in each region were consistent with current evidence-based recommendations for DED. METHODS: An online survey was distributed to optometrists (Australia, n = 654; UK, n = 1006). Respondents provided information about practice modality, years of optometric experience, preferred diagnostic and management strategies (stratified by DED severity) and the information/evidence base used to guide patient care. RESULTS: A total of 317 completed surveys were received (response rates, Australia: 21%, UK: 17%). Optometrists in both regions demonstrated similarly strong knowledge of tear film assessment and adopted both subjective and objective techniques to diagnose DED. Patient symptoms were considered the most important, valuable and commonly performed assessment by both Australian and UK respondents. UK practitioners valued and utilised conjunctival signs and tear meniscus height assessments more than Australian optometrists (p < 0.05), who placed relatively greater emphasis on sodium fluorescein tear break-up time to diagnose DED (p < 0.05). Clinicians in both locations tailored DED therapy to severity. While practitioners in both regions predominantly managed mild DED with eyelid hygiene and tear supplementation, Australian optometrists indicated prescribing topical corticosteroid therapy significantly more often than UK practitioners for moderate (14% vs 6%) and severe (52% vs 8%) disease (p < 0.05). The major source of information used to guide practitioners' dry eye management practices was continuing education conferences. CONCLUSIONS: This study highlights a range of parallels and divergences in dry eye clinical practice between Australian and UK optometrists. Our data identify both areas of strength in the adoption of evidence-based practice, as well as some potential to improve international translation of dry eye research evidence into practice.

Impact of Eye Cosmetics on the Eye, Adnexa, and Ocular Surface.

Despite the fact that cosmetic products undergo rigorous testing to ensure they are safe for human use, some users report mild discomfort following their application. The cutaneous changes, such as allergic dermatitis, are well reported, but the ocular changes associated with eye cosmetic use are less so. Some pigmented cosmetic products may accumulate within the lacrimal system and conjunctivae over many years of use, but immediate reports of eye discomfort after application are most common. Changes to the tear film and its stability may occur shortly after application, and contact lens wearers can also be affected by lens spoliation from cosmetic products. Additionally, creams used in the prevention of skin aging are often applied around the eyes, and retinoids present in these formulations can have negative effects on meibomian gland function and may be a contributing factor to dry eye disease. The aim of this review is to summarize current knowledge regarding the impact of cosmetic products on the eye, ocular surface, and tear film.

Budget impact assessment of Aprokam® compared with unlicensed cefuroxime for prophylaxis of post-cataract surgery endophthalmitis.

BACKGROUND: Intracameral cefuroxime is recommended as prophylaxis against postoperative endophthalmitis (POE) following cataract surgery. Aprokam is the only licensed product for prophylaxis of POE, although unlicensed intracameral cefuroxime may be administered using pre-filled syringes (PFS), either prepared in hospital by reconstituting cefuroxime via serial dilution (prepared PFS), or commercially purchased (purchased PFS). This study aimed to estimate the potential budget impact of using Aprokam over unlicensed cefuroxime for intracameral administration. METHODS: A budget impact model (BIM) was developed from UK NHS hospital perspective to estimate the economic impact of adopting Aprokam compared with purchased PFS or prepared PFS for the prophylaxis of POE following cataract surgery over a 5-year time horizon. The BIM incorporated direct costs only, associated with the acquisition, delivery, storage, preparation, and administration of cefuroxime. Resource utilisation costs were also incorporated; resource utilisation was sourced from a panel survey of hospital pharmacists, surgeons, and theatre nurses who are involved in the delivery, storage, preparation, quality assurance, or administration of cefuroxime formulations. Unit costs were sourced from NHS sources; drug acquisition costs were sourced from BNF. The model base case used a hypothetical cohort comprising of 1000 surgeries in the first year and followed a 5.2 % annual increase each year. RESULTS: The model predicts Aprokam is cost saving compared with purchased PFS, with a modest increase compared prepared PFS over 5 years. There are total savings of £ 3490 with Aprokam compared with purchased PFS, driven by savings in staff costs that offset greater drug acquisition costs. Compared with prepared PFS, there are greater drug acquisition costs which drive an increased total cost over 5 years of £ 13,177 with Aprokam, although there are substantial savings in staff costs as well as consumables and equipment costs. CONCLUSIONS: The lower direct costs of using Aprokam compared with purchased PFS presents a strong argument for the adoption of Aprokam where purchased PFS is administered. The additional benefits of Aprokam include increased liability coverage and possible reduction in dilution errors and contaminations; as such, in hospitals where unlicensed prepared PFS is used, modest additional resources should be allocated to adoption of Aprokam.

Migration of Cosmetic Products into the Tear Film.

PURPOSE: To examine, record, and quantify the migration of a conventional eye cosmetic pencil when applied to periocular skin in two different locations: behind the lash line (ELI) and along the periocular skin (ELO). METHODS: This was a pilot study (prospective, randomized crossover design) involving two visits on separate days. Three female subjects were randomly assigned one of two eyeliner application conditions: ELI (inside the lash line) or ELO (anterior to the lash line). Pencil eyeliner ("Glimmerstick" in Graphite; Avon, Northampton, United Kingdom) was applied to the subject's upper and lower right eyelid by the examiner. Slitlamp video recording of glitter particles suspended within the tear film was conducted for 30 sec on 10 occasions up to 2 hr post-eyeliner application. The number of glitter particles suspended in the tear film, analyzed using ImageJ software, is reported. RESULTS: The migration of the glitter particles occurred more readily in ELI application, with maximum contamination of the tear film achieved 5 to 10 min post-application. The migration of eyeliner following ELO application was comparatively slower and reduced compared with ELI application. The quantity of glitter particles suspended in the tear film varied between subjects; however, 2 hr post-application, contamination of the tear film from pencil eyeliner was negligible. CONCLUSIONS: Pencil eyeliner migrates most readily and maximally contaminates the tear film when applied posterior to the lash line. This has implications for contact lens wearers and patients with dry eye syndrome or sensitive eyes. Eye cosmetic usage for participants involved in anterior eye and contact lens research should be carefully considered in the design of studies.

Repeatability and Diurnal Variation of Tear Ferning Test.

OBJECTIVES: To investigate tear ferning (TF) test repeatability between sessions by observing changes in the tear fern pattern during the day. METHODS: Twenty-three healthy young adults (15 men and 8 women), ranging in age from 20 to 32 years (mean ± SD: 22.9 ± 3.3 years) without signs or symptoms of dry eye disease, ocular disease, or contact lens wear were enrolled in the study. Schirmer I, tear break-up time (TBUT) test, and McMonnies questionnaire were used to screen volunteers. Schirmer I and TBUT tests were applied to both eyes in each subject. Four samples of tear fluid were collected from the right eye of each subject using glass capillaries at set intervals during a single day (9 AM, 11 AM, 2 PM, and 4 PM). The TF patterns obtained from samples were classified according to the Masmali TF grading scale to increments of 0.1. RESULTS: The median values obtained from the McMonnies, Schirmer, and TBUT tests were 4.0 ± 2.0, 30.0 ± 7.0 mm (OD), and 16.0 ± 10.0 sec (OD), respectively. There were no statistically significant differences between the TF grades for tear samples collected at different times of the day (Wilks' Lambda, P = 0.351). The majority (84.8%) of TF grades was between 0.0 and 1.5; the remaining 15.2% of subjects had TF between grades 1.6 and 1.9. The overall mean grade for the TF was 1.1 ± 0.3. There were small insignificant correlations between TF grades and the McMonnies questionnaire (r = 0.1.30) and TBUT (r = 0.248) and a negligible correlation with Schirmer test (r = -0.046). CONCLUSIONS: The results found no significant differences within the TF for tear samples collected at different times of the day, suggesting that there is little diurnal variation evident.

The relationship between tear meniscus regularity and conjunctival folds.

PURPOSE: To investigate the capability of a new portable digital meniscometer (PDM) to measure tear meniscus radius (TMR) and tear meniscus height (TMH) at different locations along the lower lid and to evaluate relationships between tear meniscus regularity and the degree of lid-parallel conjunctival folds (LIPCOFs). METHODS: Using the PDM, the TMR and TMH of 42 subjects were measured at three locations along the lower lid of one eye: central, perpendicularly below the pupil center (TMR-C, TMH-C), and temporal (TMR-T, TMH-T) and nasal (TMR-N, TMH-N), perpendicularly below the limbus. Nasal and temporal LIPCOF grades were recorded. Correlations between the measurements were analyzed using the Pearson coefficient (or Spearman rank in nonparametric data), and the differences were evaluated by paired t tests or analysis of variance and post hoc Fisher least significant difference test. RESULTS: Temporal TMR was 0.041 mm flatter (p = 0.002) and TMH-T was 0.063 mm higher (p < 0.001), whereas TMR-N was 0.026 mm flatter (p = 0.038) and TMH-N was 0.046 mm higher (p < 0.001) than TMR-C and TMH-C. Temporal LIPCOF grades were significantly correlated to temporal alterations in TMH (r = 0.590; p < 0.001) and TMR (r = 0.530; p < 0.001), and nasal LIPCOF grades were significantly correlated to nasal alterations in TMH (r = 0.492; p = 0.001) and TMR (r = 0.350; p = 0.023). CONCLUSIONS: The PDM is able to noninvasively detect significant differences in TMR and TMH along the lower lid. The flatter TMR and higher TMH at the nasal and temporal locations are associated with increased LIPCOF. Because increased LIPCOF scores may affect tear film disruption along the lower lid, measuring TMR and TMH at the central position below the pupil may provide the best intersubject reliability.

A new portable digital meniscometer.

PURPOSE: The aims of this study were (i) to develop a new portable slit-lamp mounted digital meniscometer (PDM) and (ii) to test its accuracy and repeatability compared to the existing Yokoi et al. videomeniscometer (VM). METHODS: We developed a novel application for an iPod or iPhone, which created an illuminated target of parallel black and white bands. This was used as a portable device with which to perform reflective meniscometry. The medians of three consecutive measurements on five glass capillaries (internal radii, 0.100 to 0.505 mm) were compared between VM and PDM at two different sessions. Also, the central lower tear meniscus radius (TMR) in 20 normal subjects (10 males and 10 females; mean [SD] age, 32.3 [9.3] years) was measured using both techniques. Correlations between the instruments were analyzed using the Pearson coefficient. Differences between sessions and instruments were analyzed using Bland-Altman plots, coefficient of repeatability, and paired t-tests. RESULTS: The PDM and VM were accurate in vitro (95% confidence interval [CI] of difference: PDM -0.0134 to +0.0074 mm, p = 0.468; VM -0.0282 to + 0.0226 mm; p = 0.775) and reproducible between sessions (95% coefficient of repeatability, 0.019 and 0.018, respectively). The mean difference between the PDM and VM in vitro was 0.0002 mm (95% CI, -0.0252 to + 0.0256; p = 0.984). In human subjects, mean (SD) TMR measured with the PDM (0.34 [0.10] mm) and VM (0.36 [0.11] mm) was significantly correlated (r = 0.940; p < 0.001), and there was no statistically significant difference between the measured TMR of the instruments (p = 0.124). CONCLUSIONS: This new slit-lamp mounted digital meniscometer produces accurate and reliable measurements and provides similar values for tear meniscus radius, in human studies, to the existing VM. The instrument is suitable for use in both research and clinical practice.

Branch retinal vein occlusion in an asymptomatic adult with cystic fibrosis.

PURPOSE: This article aims to describe a case of asymptomatic branch retinal vein occlusion (BRVO) in a patient with cystic fibrosis (CF) and discuss the possible link between the two. CASE REPORT: A young adult (aged 35 years) with CF who presented for routine ocular examination was found to have a superior temporal BRVO in the left eye. Visual acuity was unaffected, measuring -0.06 LogMAR, and intraocular pressure was 10 mm Hg. Optical coherence tomography showed no macular involvement. Regarding the patient's general health, blood pressure was within the normal range, and there was no diabetes. Exploratory blood tests revealed elevated fibrinogen levels. CONCLUSIONS: It is hypothesized that BRVO occurred secondary to raised fibrinogen levels, a common feature in CF resulting from chronic pulmonary infection and inflammation. Practitioners should be aware of the possible link between BRVO and CF.

Comparison of Javal-Schiøtz keratometer, Orbscan IIz and Pentacam topographers in evaluating anterior corneal topography.

CLINICAL RELEVANCE: Inter-instrument variation in anterior corneal shape (ACS) measurement has a consequence for ocular clinical practice. BACKGROUND: To consider inter-instrument variability in keratometry measurements across the ACS and to explore instrument protocols for determining ACS keratometric analogues (KAs). METHODS: Mean keratometry/KAs of the right eye were recorded using Javal-Schiøtz keratometer (J-S), Orbscan IIz and Pentacam from 124 subjects (78 females; mean ± SD age: 24.71 ± 6.61 years). Mean radii of curvature were obtained for 1-mm wide annular zones extending up to 6 mm (horizontally) and 4 mm (vertically) from the apex for Orbscan and Pentacam. Zonal mean radius of curvature was calculated by averaging keratometry values for all measured points within the zone. RESULTS: KA (mean ± SD): Horizontal: Orbscan (7.80 ± 0.31 mm) and J-S (7.82 ± 0.29 mm) were not significantly different (p = 0.072). Pentacam (7.86 ± 0.29 mm) was significantly flatter than J-S (p < 0.001) and Orbscan (p < 0.001). Vertical: Orbscan (7.64 ± 0.31 mm) was significantly steeper than J-S (7.67 ± 0.29 mm, p < 0.005) and Pentacam (7.70 ± 0.29 mm, p < 0.001). Pentacam was significantly flatter than J-S (p < 0.001) and significant flatter than Orbscan across the entire profile (1-4 mm zones horizontal and vertical, p < 0.001).                        LoAs (CI): J-S/Orbscan: ±0.75 mm (0.05-0.18); J-S/Pentacam: ±0.72 mm (0.01-0.12); Pentacam/Orbscan: ±0.16 mm (0.04-0.08). There was a +0.03 mm positive bias for Orbscan compared to J-S, +0.06 mm positive bias for Orbscan compared to Pentacam and -0.03 mm negative bias for Pentacam compared to J-S. CONCLUSIONS: Algorithms used by Orbscan and Pentacam to solve the peripheral paraxial ray problem produce significantly different KAs. Instrument-specific KAs cannot be used inter-changeably between instruments. Differences in KA between instruments are not significant for ocular surgery, but may influence rigid contact lens fitting. Pentacam measures flatter than Orbscan and J-S.

Demodex Blepharitis: A Survey-Based Approach to Investigate Knowledge, Attitudes, and Practices Among Optometrists in India.

Purpose: To investigate the knowledge, attitudes, and practice towards Demodex blepharitis among optometrists in India. Methods: The study was conducted in the form of an online survey using Research Electronic Data Capture (REDCap). The survey link was distributed via direct e-mail and social media platforms, and it was comprised of 20 questions divided into two sections. The first section focused on the practitioners' demographics and their views on the general health of the eyelid. The second section of the survey was specific and aimed at obtaining information on identifying and treating Demodex blepharitis, and was only completed by those respondents who looked for Demodex mites. Results: The survey was completed by 174 optometrists. The prevalence of blepharitis in the general population was judged by the respondents to be 40%, whereas the prevalence of Demodex mites was estimated to be 29%. Interestingly, the prevalence of Demodex mites in people with blepharitis was estimated to be 30%. This estimated prevalence was substantially lower than that reported in the literature on the subject. 66% of participants believed Demodex mites to be a significant cause of ocular discomfort, whereas only 30% of participants would intervene to diagnose and manage Demodex blepharitis in their patients. Optometrists differed in their preferred method of diagnosis and management of Demodex infestation in eyelids. Conclusion: The result of this survey suggests that Demodex blepharitis is a highly under-diagnosed condition in India, with nearly 30% of surveyed optometrists managing this condition. The study also observed a lack of awareness and consensus among surveyed optometrists with regards to diagnosis and appropriate treatment methods to control Demodex infestation in eyelids.

A comparison of an eyelid-warming device to traditional compress therapy.

PURPOSE: To assess the warming and humidifying effect and ocular safety of the Blephasteam® eyelid-warming device vs. warm and moist compresses in healthy volunteers. METHODS: Twenty subjects (8 females, 12 males; mean age 39.2 years) were included in the study. Temperature and relative humidity were measured over a period of 10 min at the lower eyelid margin of one randomly selected eye during application of the Blephasteam device and, 1 h later, during application of warm compresses (in a randomized order). Ocular signs and visual acuity were assessed before and after each application. RESULTS: The mean duration of warming (temperature ≥38°C) was significantly longer with Blephasteam than with compresses (7.5 vs. 1.0 min; p < 0.01). There was no significant difference between treatments in the duration of 100% relative humidity. Compared with pretreatment values, visual acuity significantly improved after Blephasteam treatment (p < 0.05) but significantly decreased after treatment with compresses (p < 0.05). Limbal redness, eyelid redness, and corneal staining scores all improved significantly after Blephasteam treatment (p < 0.05 for all). Ocular signs did not change after compress treatment except conjunctival redness, which was significantly increased (p = 0.01 vs. pretreatment). CONCLUSIONS: The Blephasteam eyelid-warming device appeared to provide more effective warming than warm and moist compresses in a group of healthy volunteers. Visual acuity, limbal redness, and eyelid redness were improved after Blephasteam use but not after treatment with compresses.

Eye cosmetic usage and associated ocular comfort.

PURPOSE: Eye cosmetics usage is commonplace and whilst some products such as eyeliner are applied with close proximity to the ocular surface, there is little knowledge of the short- and long-term ocular effects of eye cosmetic formulations. This study aimed to investigate the use of eye cosmetics and identify any relationships between ocular comfort and cosmetic usage. METHODS: Results were collated from an online survey comprising 23 questions that recorded demographics, Ocular Surface Disease Index (OSDI) score, extent and range of eye cosmetic use and perceived comfort differences with and without eye cosmetics. RESULTS: The 1360 female respondents (median age 25, interquartile range 20-34 years) completed the survey; 83% reported using eye cosmetics regularly (≥ 3 times per week) with mascara being most commonly used. Fifty three per cent used at least three different eye cosmetics products regularly. OSDI scores of cosmetics users were similar to non-users (p = 0.083), but perceived comfort was greater when cosmetics were not used (p < 0.001). In occasional cosmetics users (use of products < 3 times per week), 65% reported a reduction in comfort when cosmetics were used. Median OSDI scores suggested a trend towards reduced comfort amongst eyeliner users (p = 0.07) although frequency and type of cosmetic products used did not appear to influence OSDI scores. CONCLUSIONS: This study shows the use of multiple eye cosmetics is extensive and associated with the perception of ocular discomfort. With such widespread use of these products, more research is required to assess the effect on the ocular surface and tear film, which may be underestimated.

Provocation of the ocular surface to investigate the evaporative pathophysiology of dry eye disease.

PURPOSE: To investigate whether standard clinical measures of tear film stability, meniscus height and symptomology reflect changes in evaporation rate induced by ocular surface provocations. METHODS: Forty participants (23.8 ± 4.5 years, 53 % female) with healthy to mild dry eyes underwent two tear film provocations in random sequence on separate occasions: playing a tablet computer high concentration game (http://slither.io/) for 30 min; and receiving treatment with humidity goggles for 10 min followed by liposomal spray application. Measures at baseline and 30 min later were: Symptom Assessment iN Dry Eye (SANDE) questionnaire, tear film lipid layer thickness (LLT), non-invasive tear film break-up time (NIBUT), tear meniscus height (TMH), dynamic tear film lipid layer pattern (DLP) and tear film evaporation (TFE). RESULTS: There were no differences in the baseline measurements before each provocation (p > 0.05). Dry eye symptoms significantly worsened with concentration task (p < 0.001) and improved with treatment (p < 0.001). DLP and LLT significantly increased with treatment (p < 0.05), but was unaffected with the concentration task (p > 0.05). NIBUT declined with the concentration task (p = 0.015), but was not enhanced with treatment (p = 0.142). TMH increased after treatment (p = 0.001) and decreased with the concentration task (p = 0.006). While evaporation decreased with the concentration task (p < 0.001), treatment had no effect (p = 0.333). LLT was associated with evaporation (p = 0.036) and additionally with symptom severity (p = 0.002) and tear volume (p = 0.017). CONCLUSIONS: Sub-classifying dry eye based on an 'evaporative' component to inform treatment seems over-simplistic. However objective TMH, NIBUT and LLT seem to be the key clinical metrics that drive ocular comfort.

Quantitative measurement of mechanical properties in wound healing processes in a corneal stroma model by using vibrational optical coherence elastography (OCE).

Corneal wound healing, caused by frequent traumatic injury to the cornea and increasing numbers of refractive surgeries, has become a vital clinical problem. In the cornea, wound healing is an extremely complicated process. However, little is known about how the biomechanical changes in wound healing response of the cornea. Collagen-based hydrogels incorporating corneal cells are suitable for replicating a three-dimensional (3D) equivalent of the cornea in-vitro. In this study, the mechanical properties of corneal stroma models were quantitatively monitored by a vibrational optical coherence elastography (OCE) system during continuous culture periods. Specifically, human corneal keratocytes were seeded at 5 × 105 cells/mL in the hydrogels with a collagen concentration of 3.0 mg/mL. The elastic modulus of the unwounded constructs increased from 2.950 ± 0.2 kPa to 11.0 ± 1.4 kPa, and the maximum thickness decreased from 1.034 ± 0.1 mm to 0.464 ± 0.09 mm during a 15-day culture period. Furthermore, a traumatic wound in the construct was introduced with a size of 500 µm. The elastic modulus of the neo-tissue in the wound area increased from 1.488 ± 0.4 kPa to 6.639 ± 0.3 kPa over 13 days. This study demonstrates that the vibrational OCE system is capable of quantitative monitoring the changes in mechanical properties of a corneal stroma wound model during continuous culture periods and improves our understanding on corneal wound healing processes.

CLEAR - Contact lens wettability, cleaning, disinfection and interactions with tears.

Contact lens materials have undergone significant changes over the past 20 years, particularly with respect to the introduction of silicone hydrogel materials. Whilst this development addressed hypoxic issues, other important areas relating to contact lens success, notably comfort, require further research. Contact lens wettability remains a crucially important part of biocompatibility. Contact lenses can be made more wettable by incorporation of surfactants into blister packs, internal wetting agents, surface treatments or care solutions. However, there remains no clear association between contact lens wettability and comfort, making it challenging to determine the potential for these approaches to be of significant clinical benefit. Most contact lenses are used on a daily wear, reusable basis, which requires them to be disinfected when not worn. The ideal disinfecting solution would also improve comfort during wear. However, balancing these requirements with other factors, including biocompatibility, remains a challenge. Soft lens materials invariably take up and subsequently release certain components of disinfecting solutions onto the ocular surface. This may affect tear film stability and the normal ocular microbiome, and further research is needed in this area to determine whether this has any affect on comfort. Finally, contact lens materials sorb components of the tear film, and these interactions are complex and may change the biochemistry of the tear film, which in turn may affect their comfort. In conclusion, the interaction between lens materials, tear film and disinfection solution plays an important role in the biocompatibility of lenses. However, the exact role and whether this can be altered to improve biocompatibility and comfort during wear remains debatable. This report summarises the best available evidence to examine this complex relationship and the opportunities for practitioners to enhance in-eye comfort of contemporary lenses, along with providing suggestions for areas of study that may provide further information on this topic.

A survey of UK practitioner attitudes to the fitting of rigid gas permeable lenses.

PURPOSE: Rigid gas permeable (GP) contact lenses may provide the safest option for lens wear, but prescribing rates are in decline. This study investigated the effect of practitioner attitudes on GP lens prescribing. METHODS: A questionnaire was developed using a focus group and a pilot study. Questions addressed clinical time spent fitting GP lenses, specialist equipment requirements and perceived safety and comfort. With ethical approval, the questionnaire was sent to 1000 randomly selected UK registered eye care practitioners (ECPs). RESULTS: In general, ECPs enjoy the challenge of fitting GPs, although fitting takes longer than soft lens fitting. There is a difference in attitude between longer qualified and more recently qualified ECPs. Longer qualified ECPs more frequently reported enjoyment of the fitting challenges, recommended GP lenses to patients and were less likely to believe that GP lenses were becoming obsolete. ECPs are in strong agreement on the ocular health advantages of fitting GPs. They do not feel specialist equipment is generally needed, although some reported a topographer to be advantageous. The large majority of ECPs do not have access to the specialist equipment they perceive to be normally associated with GP fitting (radiuscope, V-gauge). They believe that initial fitting discomfort of GP fitting is a major drawback to their fitting, and while they feel this greatly improves with adaptation, they do not feel it reaches soft lens wear comfort. A total of 30.3% of ECPs feel it is clinically acceptable to use topical anaesthetic during GP fitting, but only 1.4% of ECPs regularly do so. CONCLUSIONS: ECPs are aware of the benefits that GP lenses provide in terms of ocular health. They find GPs take longer to fit, but they enjoyed the challenge of fitting, which suggests that they are not lacking in clinical skill, nor any specialist equipment. However, they are unhappy with initial patient comfort, and are not yet prepared to use topical anaesthetics during initial fitting. As a consequence, ECPs believe that GP lenses are becoming obsolete. Negative practitioner attitudes toward various aspects of GP fitting may mean fewer recommendations to patients and reduced GP prescribing.

Improved Demodex diagnosis in the clinical setting using a novel in situ technique.

PURPOSE: To compare existing and novel diagnostic techniques for confirming ocular Demodex infestation and to recommend the most reliable method for routine use by eye care practitioners, based on yield and clinical applicability. METHODS: Fifteen participants with a prior Demodex blepharitis diagnosis or featuring typical cylindrical dandruff (CD) collarettes, and seven healthy controls were enrolled. Demodex presence was assessed using five techniques, applied consecutively, on a minimum of two different eyelashes on each eyelid of every participant, for each test, in situ: 1. using fine-point forceps and 25-40x biomicroscopy magnification, by eyelash rotation as proposed by Mastrota (ROT); 2. by removing cylindrical dandruff and exposing the eyelash insertion point at the lid margin (CDR); and 3. by laterally tensioning the eyelash (LET) following CDR. The typical appearance of cigar-shaped mite tails protruding from each assessed eyelash follicle was observed, and mite tails counted and averaged per participant for each assessment technique. 4. Lash epilation, and mite presence evaluated using bright-field microscopy at 10-40x magnification (EPI). 5. Finally, eyelash follicles were imaged using in vivo confocal microscopy (IVCM) and the images visually inspected for mite presence. RESULTS: In the Demodex group, the highest numbers of mites/eyelash were identified by LET (3.8 ± 1.4), versus CDR (2.4 ± 1.6) and ROT (1.1 ± 1.2), alone (all p < 0.002). An average of 1.0 ± 0.8 mites/lash was identified by EPI. IVCM failed to offer unequivocal evidence of Demodex presence even in confimed cases. CONCLUSIONS: A novel technique for the clinical diagnosis and grading of Demodex in situ is described. By removing cylindrical dandruff and applying static, lateral tension to the eyelash without epilation, large numbers of mites are visible at the exposed eyelash follicle. The proposed method is convenient and clinically applicable, requiring only forceps and 25-40x biomicroscope magnification, and allowing rapid, efficient evaluation of large numbers of eyelashes.