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Dive into the research topics where Katharine Evans is active.

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Featured researches published by Katharine Evans.


Ophthalmic and Physiological Optics | 2009

Tear ferning in contact lens wearers.

Katharine Evans; R. V. North; Christine Purslow

Tear ferning (TF) has shown good sensitivity and specificity in the diagnosis of dry eye, but is a relatively uncommon test, especially in contact lens wearers. The aim of this study was to investigate the relationship between TF, ocular comfort and tear film stability amongst contact lens (CL) wearers and non‐contact lens (NCL) wearers. Subjects (36 NCL, 24 CL; mean age 23.2 ± 4.8 years) underwent assessment of non‐invasive tear break up time (NIBUT), fluorescein tear break up time (FBUT) and completed the Ocular Comfort Index (OCI) questionnaire. Non‐stimulated tears were collected from the inferior tear meniscus with a glass capillary. Samples of 1.5 μL were air dried, observed by light microscopy and the TF pattern quantified according to Rolando’s grading scale. Significantly higher grades of TF pattern and discomfort (higher OCI scores) were observed in CL wearers compared to NCL wearers (Mann–Whitney U‐test; p < 0.005 and p < 0.05 respectively). Differences in tear film stability were not significant between groups. Even when asymptomatic (low OCI scores) CL and NCL subjects were compared, TF remained significantly different (p < 0.005). In both CL and NCL subjects, TF displayed poor correlation with tear film stability tests and OCI scores. Higher TF grades in CL wearers, even if asymptomatic, indicate an unfavourable ratio of salt to macromolecule concentration within the tear film of such subjects. The lack of significant difference in TF between symptomatic CL and NCL wearers could suggest similar aetiology (tear film hyperosmolarity) in each cohort. The TF technique demonstrates limited sensitivity and specificity for the prediction of ocular surface comfort in both CL and NCL wearers.


Ophthalmic and Physiological Optics | 2012

Eye cosmetic usage and associated ocular comfort

Alison Ng; Katharine Evans; R. V. North; Christine Purslow

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.


Eye & Contact Lens-science and Clinical Practice | 2016

Impact of eye cosmetics on the eye, adnexa, and ocular surface

Alison Ng; Katharine Evans; R. V. North; Lyndon Jones; Christine Purslow

Abstract: 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.


Eye & Contact Lens-science and Clinical Practice | 2015

Migration of cosmetic products into the tear film

Alison Ng; Katharine Evans; R. V. North; Christine Purslow

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 subjects 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.


Computational and Mathematical Methods in Medicine | 2016

Defining the Optimal Region of Interest for Hyperemia Grading in the Bulbar Conjunctiva

María Luisa Sánchez Brea; Noelia Barreira Rodríguez; Antonio Mosquera González; Katharine Evans; Hugo Pena-Verdeal

Conjunctival hyperemia or conjunctival redness is a symptom that can be associated with a broad group of ocular diseases. Its levels of severity are represented by standard photographic charts that are visually compared with the patients eye. This way, the hyperemia diagnosis becomes a nonrepeatable task that depends on the experience of the grader. To solve this problem, we have proposed a computer-aided methodology that comprises three main stages: the segmentation of the conjunctiva, the extraction of features in this region based on colour and the presence of blood vessels, and, finally, the transformation of these features into grading scale values by means of regression techniques. However, the conjunctival segmentation can be slightly inaccurate mainly due to illumination issues. In this work, we analyse the relevance of different features with respect to their location within the conjunctiva in order to delimit a reliable region of interest for the grading. The results show that the automatic procedure behaves like an expert using only a limited region of interest within the conjunctiva.


Optometry and Vision Science | 2017

Impact of Dry Eye Symptoms and Daily Activities in a Modern Office

Mirjam M. van Tilborg; Paul J. Murphy; Katharine Evans

PURPOSE Modern offices and the use of electronic devices are increasing factors in work-related eye symptoms. However, symptoms of eye fatigue or dry eye sensation can be mixed and confusing. This study surveys the eye symptoms reported during a working day at modern offices to investigate the possible inhibition on daily work activities. METHODS Two online digital surveys were sent to three different work locations, by direct e-mail. Survey A consisted of 14 questions that investigated eye symptoms experienced during daily activities at work and the impact on daily activities. Survey B consisted of four general questions, the Dutch Ocular Surface Disease Index, the Work Productivity and Activity Index, and the Illness Perception Questionnaire. RESULTS A total of 505 participants completed survey A, and 213 completed survey B. The participants reported that a high proportion of their day was spent working on a computer (60%). The majority experienced an air draft (79.1%) and had no adjustable light (81.5%) at their workspace. Dry eye-related symptoms were reported at a significantly higher frequency at work than at home (P < .001). Up to 70% experienced some inhibition of daily activity at work due to eye symptoms, with more than 5% experiencing symptoms most or all of the time. Indoor environment, work environment, and general health were perceived as the main reasons for developing dry eye. Compared with males, females showed a statistically significant higher Ocular Surface Disease Index score (P < .001) and experienced more inhibition and adverse effects on daily life and work productivity. CONCLUSIONS This investigation shows that dry eye symptoms have a negative impact on daily activities at work. These findings suggest that multidisciplinary understanding of the negative impact of dry eye by a range of specialists will be of help in managing work-related dry eye.


Optometry and Vision Science | 2017

Investigating the Short-term Effect of Eyelid Massage on Corneal Topography

Britta Riede-Pult; Katharine Evans; Heiko Pult

PURPOSE The aim of this study was to evaluate the short-term effect of eyelid massage, after the use of warm compresses, on corneal topography. METHODS Corneal topography was evaluated on 20 subjects (mean age, 47.0 [SD ±17.3] years) using the Oculus Keratograph (Oculus, Wetzlar, Germany). Corneal eccentricity (Epsilon) was compared between topography measurements before eyelid warming (using warm compresses) (T1), after eyelid warming (T2), directly after eyelid massage (T3), and 30 minutes after eyelid massage (T4). Differences in corneal eccentricity between the enrolment measurement (T1) and consecutive measurements (T1-4) were analyzed. The contralateral eye-treated by warm compresses, but not by eyelid massage-was the control. Visual acuity (decimal), bulbar conjunctival hyperemia, and corneal staining (Cornea and Contact Lens Research Unit grading scale) were evaluated at T1 and T4 to assess clinical safety. RESULTS No significant differences were found between consecutive eccentricity measurements overall and with the central radii (repeated-measures analysis of variance, P > .238 (massaged eyelid: Epsilon T1: 0.48 [95% confidence interval, ±0.07], T2: 0.49 [±0.05], T3: 0.49 [±0.06], T4: 0.48 [±0.06]; horizontal radii T1: 7.76 [±0.13] mm, T2: 7.74 [±0.13] mm, T3: 7.75 [±0.13] mm, T4: 7.76 [±0.13] mm; vertical radii T1: 7.56 [±0.12] mm, T2: 7.55 [±0.10] mm, T3: 7.54 [±0.10] mm, T4: 7.58 [±0.11] mm). Decimal visual acuity significantly improved at the end of the study (massaged eyelid: T1: 1.1 [±0.1]; T4: 1.3 [±0.1]; P < .032). No significant differences were detected between the consecutive evaluation of corneal staining (Wilcoxon test; P > .285). Redness was not significantly different between time points (repeated-measures analysis of variance; P = .187) in the colateral eyes. Hyperemia was significantly reduced in the massaged eyes (T1: 2.0 grade units [±0.3]; T4: 1.9 [±0.3]; P = .021). CONCLUSIONS Eyelid warming followed by eyelid massage appears to be a safe procedure, without any clinically relevant short-term effects on the cornea.


Middle East African Journal of Ophthalmology | 2016

Characteristics of keratoconic patients attending a specialist contact lens clinic in Kenya

Zahra Aly Rashid; Michel Millodot; Katharine Evans

Purpose: To describe the characteristics of keratoconus (KC) patients seen in a contact lens clinic of a children′s hospital in Kenya. Methods: This was a retrospective study of patient′s records with KC. Data collected included gender, age at presentation, source of referral, main complaint at referral, severity of KC, best-corrected visual acuity (BCVA), and management before the presentation and following assessment. Results: A total of 254 patients′ records were analyzed. Mean age at presentation to the clinic was 20.97 ± 11.13 year (range, 6-84 years) with 75% between the ages of 6 and 25 years. There was a preponderance of males (59.8%). Most patients were referred by an ophthalmologist. All patients were Africans. The most common complaints were blurred vision (50%), poor visual acuity with spectacles (33.5%), contact lens intolerance (11.8%), and other (unspecified). Most cases were severe (71%) followed by moderate (22.9%) and mild (6.2%). Mean BCVA was 0.24 ± 0.23 (6/11). An optical correction was provided in 98% of cases; 34.6% with spectacles, 31.1% with gas permeable lenses and the remaining with both. Referral for keratoplasty was warranted in 16.5%. Conclusion: This is the first study of KC conducted in Kenya. KC presented at a very early age and tended to be severe. Ophthalmologists were the main source of referral. The main presenting symptom was reduced vision. Optical correction was the most common management and the percentage of patients referred for surgery concurred with other studies.


Optometry and Vision Science | 2014

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

Rachel Hiscox; Christine Purslow; R. V. North; Ian Ketchell; Katharine Evans

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.


international symposium on neural networks | 2017

Assessment of the repeatability in an automatic methodology for hyperemia grading in the bulbar conjunctiva

Luisa Sánchez Brea; Noelia Barreira Rodríguez; Antonio Mosquera González; Katharine Evans

When the vessels of the bulbar conjunctiva get congested with blood, a characteristic red hue appears in the area. This symptom is known as hyperemia, and can be an early indicator of certain pathologies. Therefore, a prompt diagnosis is desirable in order to minimize both medical and economic repercussions. A fully automatic methodology for hyperemia grading in the bulbar conjunctiva was developed, by means of image processing and machine learning techniques. As there is a wide range of illumination, contrast, and focus issues in the images that specialists use to perform the grading, a repeatability analysis is necessary. Thus, the validation of each step of the methodology was performed, analyzing how variations in the images are translated to the results, and comparing them to the optometrists measurements. Our results prove the robustness of our methodology to various conditions. Moreover, the differences in the automatic outputs are similar to the optometrists ones.

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Antonio Mosquera González

University of Santiago de Compostela

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Michel Millodot

Hong Kong Polytechnic University

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Hugo Pena-Verdeal

University of Santiago de Compostela

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