Non-contact Lens Wearers Research Articles

Long-Term Impacts of Orthokeratology Treatment on Sub-Basal Nerve Plexus and Corneal Sensitivity Responses and Their Reversibility.

To examine the effects of one year of overnight orthokeratology (OK) treatment on the sub-basal nerve plexus (SBNP) and corneal sensitivity and to assess the reversibility of these effects one month after treatment interruption. Thirty-two subjects with low-moderate myopia underwent OK treatment for one year. Fifteen non-contact lens wearers served as controls. At the time points baseline, one year of treatment, and one month after removing the OK lenses, two tests were conducted: corneal sensitivity (Cochet-Bonnet esthesiometer) and SBNP imaging by in vivo confocal microscopy. In participants wearing OK lenses, significant reductions over the year were produced in SBNP nerve density (P=0.001 and P=0.006) and number of nerves (P<0.001 and P=0.001) in the central and mid-peripheral cornea, respectively. Differences over the year were also detected in central objective tortuosity (P=0.002). After lens removal, baseline values of nerve density (P=0.024 and P=0.001) and number of nerves (P=0.021 and P<0.001) for the central and mid-peripheral cornea, respectively, were not recovered. At one month post-treatment, a difference was observed from one-year values in central corneal sensitivity (P=0.045) and mid-peripheral Langerhans cell density (P=0.033), and from baseline in mid-peripheral objective tortuosity (P=0.049). Direct correlation was detected at one year between nerve density and tortuosity both in the central (P<0.01; r=0.69) and mid-peripheral cornea (P<0.01; r=0.76). Long-term OK treatment led to reduced SBNP nerve density and this was directly correlated with corneal tortuosity. After one month of treatment interruption, nerve density was still reduced.

The effect of the timing of the cessation of contact lens use on the results of biometry.

Current guidelines vary regarding when to remove contact lenses prior to performing biometry, and there is no clear evidence behind these guidelines. This study aimed to determine the effect of soft contact lens wear on biometric measurements by examining the change in predicted lens power for emmetropia at several time points following removal of soft contact lenses. A prospective, controlled study of healthy soft contact lens wearers. Biometry was performed immediately after removing contact lenses and then after 2, 4 and 7 days of no contact lens use. Healthy non-contact lens wearers were used as controls. All measurements were taken with the Zeiss IOLMaster. In all, 14 subjects and 13 controls were recruited. There was no significant difference in age or gender between groups. Eight of the fourteen subjects wore daily disposable CLs, two wore 2-weekly and four wore monthly soft CLs. Measurements from controls and contact lens-wearing subjects showed similar degrees of variation over time. The within-subject SD in predicted intraocular lens (IOL) power for emmetropia for contact lens wearers was 0.20 D (95% CI 0.16-0.25 D) compared to 0.18 D (95% CI 0.12-0.26 D) for controls. There is a significant variation in UK practice regarding advice on the timing of cessation of contact lens wear prior to having biometry performed. Our study suggests that it is likely that soft contact lens wearers are currently being advised to remove their contact lenses for an unnecessarily long period of time prior to having biometry performed.

Ocular surface and tear film status among contact lens wearers and non-wearers who use VDT at work: comparing three different lens types.

To analyze differences in the ocular surface appearance and tear film status of contact lens wearers and non-wearers in a group of visual display terminals (VDT) workers and additionally to assess differences between lens materials. Cross-sectional study of 236 office workers, of whom 92 were contact lens wearers. Workers provided information on their contact lenses (conventional hydrogel, silicone hydrogel or rigid gas permeable lenses) and exposure to VDT at work. Ocular surface and tear film status were determined by the presence of bulbar, limbal and lid redness, lid roughness and corneal staining type, and by Schirmer's and tear break-up time tests (TBUT). A generalized linear model was used to calculate the crude (cRR) and age- and sex-adjusted (aRR) relative risk to measure the association between ocular surface and tear film abnormalities and contact lens use and type. The aRR of ocular surface abnormalities was higher in contact lens wearers compared to non-wearers: bulbar redness (aRR 1.69; 95% CI 1.25-2.30), limbal redness (aRR 2.87; 1.88-4.37), lid redness (aRR 2.53; 1.35-4.73) and lid roughness (aRR 7.03; 1.31-37.82). VDT exposure > 4h/day increased wearers' risk of limbal and lid redness. Conventional hydrogel wearers had the highest risk of ocular surface abnormalities, followed by silicone hydrogel wearers. Both contact and non-contact lens wearers had a high prevalence of altered TBUT (77.3 and 75.7% respectively) and Schirmer (51.8 and 41.3%). Regular contact lens use during VDT exposure at work increases risk of bulbar, limbal and lid redness, and lid roughness, especially in soft contact lens wearers. The high prevalence of altered TBUT and Schirmer's results in all participants suggests that VDT use greatly affects tear film characteristics.

Changes in Tear Cytokines Following a Short Period of Daily and Overnight Silicone Hydrogel Lens Wear

Background and Objective: To investigate changes in ocular surface inflammatory markers after daily and overnight silicone hydrogel contact lens wear in healthy wearers.&#x0D; Material and Methods: Twenty-six experienced soft contact lens subjects were evaluated at baseline, after 1-day of silicone hydrogel lens wear, and after 1-night of wear. Basal tears were collected at each visit and tear cytokine concentrations were quantified using multiplex [interleukin (IL)-1β, IL-6, IL-10, IL-12(p70), IL-17A and tumor necrosis factor (TNF)-α] or ELISA (IL-8) kits. A historical control group of 27 non-contact lens wearers was used to compare absolute concentrations and diurnal variations in tear cytokine concentrations. Changes in cytokine concentrations were analyzed using linear mixed models. Linear regression with bootstrapping was used to assess whether changes in IL-1β concentrations were associated with changes in other cytokines.&#x0D; Results: IL-8 concentrations decreased after 1 day of silicone hydrogel contact lens wear and returned to baseline levels the next morning (p=0.04). This same diurnal fluctuation was seen in non-contact lens wearers (p=0.03). With daily contact lens wear, there was a significant positive correlation between the changes in IL-1β and IL-8, TNF-α, IL-10 and IL-12(p70) (all p&lt;0.03). With overnight contact lens wear, there were significant positive correlations between the changes in IL-1β and IL-6, IL-17A and TNF-α (all p&lt;0.01).&#x0D; Conclusion: A short period of daily and overnight silicone hydrogel lens wear does not significantly alter the inflammatory status in adapted soft contact lens wearers.

Free-Living Amoebae Keratitis

To describe the diagnostic and clinical features and treatment results in 43 consecutive patients with microbiologically proven free-living amoebae (FLA) keratitis. In this hospital-based, prospective case series, corneal scrapings from 43 patients with presumed amoebic keratitis were plated on nonnutrient agar. Amoebic isolates were identified morphologically and by the polymerase chain reaction. All patients with culture-proven FLA keratitis were treated with polyhexamethylene biguanide (PHMB) 0.02% eye drops. Forty-three corneal scrapings from 43 patients were found to be culture positive for FLA; 41 (95%) were from contact lens wearers and 2 (5%) were from noncontact lens wearers. Microscopic examination identified 4 Acanthamoeba spp, 24 Hartmannella spp, 12 vahlkampfiid amoebae, and 3 mixed infections with Hartmannella/vahlkampfiid amoebae. Morphological results were confirmed by the polymerase chain reaction. Patients with Acanthamoeba, Hartmannella, and vahlkampfiid keratitis had indistinguishable clinical features. In 38 eyes with keratitis at an early stage, treatment with PHMB 0.02% eye drops was fully successful. In 5 patients with advanced keratitis, topical PHMB 0.02% controlled the infection, but all of them developed a central corneal scar with visual deterioration. Acanthamoeba is not the only cause of amoebic keratitis, because this condition may also be caused by other FLA, such as Hartmannella and vahlkampfiid amoebae. This finding is epidemiologically interesting, suggesting a possible different geographical prevalence of the different FLA responsible for keratitis. Early diagnosis and proper antiamoebic treatment are crucial to yielding a cure.

The natural history of corneal topographic progression of keratoconus after age 30 years in non-contact lens wearers

Background/aimsTo determine if significant progression of disease occurs in older, non-contact lens wearing, subjects with keratoconus and to identify potential predictive factors.MethodsClinical and computerised corneal topography records of subjects with...

Interpreting the corneal response to oxygen: Is there a basis for re-evaluating data from gas-goggle studies?

When anoxia (0% oxygen) is created within a gas-tight goggle, ocular physiological responses, including corneal swelling, limbal hyperaemia and pH change, are known to vary, depending on the presence or absence of a low, oxygen transmissibility contact lens. A new theory is proposed to account for this discrepancy based on the concept of lid derived oxygen, whereby oxygen originating from the vascular plexus of the palpebral conjunctiva supplements that available to the ocular surface in an open, normally blinking eye, even when the surrounding gaseous atmosphere is anoxic. The effect of a lid derived contribution to corneal oxygenation was assessed by using existing experimental data to model open-eye, corneal swelling behavior as a function of atmospheric oxygen content, both with and without the presence of a contact lens. These models predict that under atmospheric anoxia, contact lens wear results in 13.2% corneal swelling compared with only 5.4% when the lens was absent. Lid derived oxygen acts to provide the ocular surface in the non-contact lens wearing, normally blinking, open-eye with up to 4.7% equivalent oxygen concentration, even within the anoxic environment of a nitrogen filled goggle. Correcting for lid derived oxygen eliminates previously observed discrepancies in corneal swelling behavior and harmonizes the models for the contact lens wearing and gas-goggle cases. On this basis it is proposed that true anoxia at the ocular surface cannot be achieved by atmospheric manipulation (i.e. a gas-goggle) alone but requires an additional presence, e.g. a low, oxygen transmissibility contact lens, to prevent access to oxygen from the eyelids. Data from previously conducted experiments in which the gas-goggle paradigm was used, may have been founded on underestimates of the real oxygen concentration acting on the ocular surface at the time and if so, will require re-interpretation. Future work in this area should consider if a correction for lid derived oxygen is necessary.

Characterization of Upper Eyelid Tarsus and Lid Wiper Dimensions.

To measure various dimensions of the upper tarsal plate and the area of upper lid wiper staining. The repeatability of the method of measurement was investigated. Thirty-five healthy non-contact lens wearers were enrolled. The following parameters were measured from digital images of the upper eyelid captured with a slitlamp camera: length, height, and total area of the tarsal plate and area of lid wiper staining (lissamine green). Measurements were performed in a randomized and masked fashion on two separate occasions by the same investigator using ImageJ (National Institutes of Health). Coefficients of repeatability (COR) were calculated. The dimensions (mean±SD) of the tarsal plate were 20.6±1.9 mm length, 7.9±0.8 mm height, and 103.3±18.8 mm total area. The area of lid wiper staining was 2.7±2.0 mm. No association was found between tarsal dimensions and lid wiper staining (all P>0.05). Image analysis COR values were 0.6 mm tarsal length, 0.1 mm tarsal height, 1.2 mm tarsal area, and 0.4 mm lid wiper staining. There was no significant difference between repeated measurements for any parameter (all P>0.05). Limits of agreement were narrow for all parameters, indicating good agreement between repeated measurements. This work has demonstrated that there is a wide range in the dimensions of the upper tarsal plate in an urban UK population. No association was found between the upper tarsal dimensions and lid wiper staining. ImageJ was shown to be a repeatable method to measure the dimensions of the upper tarsal plate and upper lid wiper staining.

Diurnal Variation in Comfort in Contact Lens and Non-contact Lens Wearers.

The purpose of this investigation was to evaluate the diurnal variation in symptoms associated with ocular discomfort in contact lens (CL) wearers and non-CL wearers. The study population comprised 604 individuals attending pre-screening visits at the OTG-i research clinic; 60% were current soft CL wearers (hydrogel and silicone hydrogel) and 40% were non-CL wearers. Symptomatology status was determined by the OSDI questionnaire (58% asymptomatic, 42% symptomatic). Participants were asked to grade their comfort, vision, and other symptoms during the day and in the evening (before lens removal for CL wearers) on 0 to 100 visual analogue scales. Diurnal decrease in comfort was significantly greater for CL wearers (-16.0 vs. -6.3, p < 0.001) and symptomatic participants (p = 0.015). Diurnal decrease in subjective vision was also significantly greater for CL wearers (-10.4 vs. -6.9, p = 0.005) and symptomatic participants (p = 0.001), and the interaction between these factors was also significant (p = 0.019). Dryness, grittiness, and irritation increased significantly more for CL wearers (p < 0.001, p = 0.012, and p = 0.004, respectively) and grittiness, irritation, and stinging for symptomatic participants (p = 0.016, p < 0.001, and p < 0.001, respectively). For the CL wearers, there was a significant interaction between dryness and age (p = 0.026) with the diurnal increase in dryness being greater in those under 40 (+15.6 vs. +10.0). The diurnal decrease in comfort and subjective vision, and the diurnal increase in dryness, grittiness, and irritation, were significantly more marked for CL wearers than non-CL wearers. Diurnal changes in comfort, grittiness, stinging, irritation, and vision were influenced by the subject's overall symptomatology as assessed by the OSDI questionnaire. For dryness symptoms, the diurnal decrease was most marked in young CL wearers. For the symptoms of stinging and vision, the diurnal changes were most pronounced in the symptomatic groups.

Corneal Sensitivity and Inflammatory Biomarkers in Contact Lens Discomfort.

The aim of this study was to analyze whether symptoms of discomfort in hydrogel contact lens (HCL) wearers were associated with changes in corneal sensitivity or levels of tear inflammatory mediators. Sixty-six subjects were included: 47 HCL wearers, further divided into 24 symptomatic and 23 asymptomatic wearers by the Contact Lens Dry Eye Questionnaire short form and 19 non-contact lens wearers. At least 24 h after HCL removal, we obtained scores from the Ocular Surface Disease Index and mechanical, hot, and cold corneal thresholds using a Belmonte esthesiometer. We collected 4 μl of tears with a capillary micropipette and measured levels of 12 inflammatory markers using a bead-based array: epidermal growth factor, fractalkine, interleukin-10 (IL-10), IL-1β, IL-1 receptor antagonist, IL-2, IL-4, IL-6, IL-8, monocyte chemoattractant protein 1, tumor necrosis factor-α, and matrix metalloproteinase 9. There were no significant differences between groups in corneal sensitivity thresholds and levels of tear molecules. The following significant correlations were found in the total sample pooled: Ocular Surface Disease Index correlated with mechanical threshold (p < 0.01; rho = -0.324) and epidermal growth factor (p < 0.01, rho = -0.330), and mechanical threshold correlated with heat threshold (p < 0.01, rho = -0.321). Twenty-four hours after HCL removal, symptoms of discomfort in HCL wearers are not related to changes in corneal sensitivity or tear inflammatory mediator levels. This might indicate either that HCL wear has no effect on these parameters or that ocular surfaces recover from HCL-caused effects during the first hours after HCL removal. However, there were correlations for associations between symptoms, corneal sensitivity, and some molecules in tears.

The use of dimethyl sulfoxide in contact lens disinfectants is a potential preventative strategy against contracting Acanthamoeba keratitis.

Acanthamoeba castellanii is the causative agent of blinding keratitis. Though reported in non-contact lens wearers, it is most frequently associated with improper use of contact lens. For contact lens wearers, amoebae attachment to the lens is a critical first step, followed by amoebae binding to the corneal epithelial cells during extended lens wear. Acanthamoeba attachment to surfaces (biological or inert) and migration is an active process and occurs during the trophozoite stage. Thus retaining amoebae in the cyst stage (dormant form) offers an added preventative measure in impeding parasite traversal from the contact lens onto the cornea. Here, we showed that as low as 3% DMSO, abolished A. castellanii excystation. Based on the findings, it is proposed that DMSO should be included in the contact lens disinfectants as an added preventative strategy against contracting Acanthamoeba keratitis.

A Survey of Dry Eye Symptoms in Contact Lens Wearers and Non-Contact Lens Wearers among University Students in Malaysia

Objective: To determine the prevalence of dry eye symptoms in contact lens wearers and non-contact lens wearers among university students, and to find out any association between dry eye symptoms and gender in these students, dry eye symptoms and computer usage in contact lens wearers. Material and methods: This study was conducted among the medical and pharmacy students aged between 18 and 28 years. Contact lens dry eye questionnaire (CLDEQ) for contact lens wearers and dry eye questionnaire (DEQ) for non-contact lens wearers were used in this study. Both forms consisted of questions on the age, gender, common symptoms and mode of relief etc. The character of the symptoms was measured with the dimensions of frequency and intensity. The filled questionnaires were analyzed using SPSS software. Results: The dry eye questionnaires were completed by 627 students (461 DEQ and 166 CLDEQ). Females 406 (64.8%) were more than males 221 (35.2%) and majority of them were non-contact lens users in both genders. Our study showed that all the symptoms of dry eye were significantly more prevalent in contact lens wearers when compared to non-contact lens wearers. The most common symptom of dry eyes experienced in contact lens wearers was dryness of eyes (73.5%), while tired eyes (77%) was the most common symptom in non-contact lens wearers. The study also showed an increasing trend in frequency and intensity of symptoms as the day passed by, with the highest intensity at the end of the contact lens wearing time. The dry eyes symptom was noted significantly more often in students using computer for more than 2 hours daily. Conclusion: Symptoms of dry eyes are more frequent in contact lens wearers than in non-contact lens wearers, with an increasing trend of their frequency and intensity at the end of the day.

Influence of Meibomian Gland Expression Methods on Human Lipid Analysis Results

PurposeTo compare the lipid composition of human meibum across three different meibum expression techniques. MethodsMeibum was collected from five healthy non-contact lens wearers (aged 20-35 years) after cleaning the eyelid margin using three meibum expression methods: cotton buds (CB), meibomian gland evaluator (MGE) and meibomian gland forceps (MGF). Meibum was also collected using cotton buds without cleaning the eyelid margin (CBn). Lipids were analyzed by chip-based, nano-electrospray mass spectrometry (ESI-MS). Comparisons were made using linear mixed models. ResultsTandem MS enabled identification and quantification of over 200 lipid species across ten lipid classes. There were significant differences between collection techniques in the relative quantities of polar lipids obtained (P<.05). The MGE method returned smaller polar lipid quantities than the CB approaches. No significant differences were found between techniques for nonpolar lipids. No significant differences were found between cleaned and non-cleaned eyelids for polar or nonpolar lipids. ConclusionMeibum expression technique influences the relative amount of phospholipids in the resulting sample. The highest amounts of phospholipids were detected with the CB approaches and the lowest with the MGE technique. Cleaning the eyelid margin prior to expression was not found to affect the lipid composition of the sample. This may be a consequence of the more forceful expression resulting in cell membrane contamination or higher risk of tear lipid contamination as a result of reflex tearing.

The influence of soft contact lens materials on the central, para-central and peripheral corneal endothelium

PURPOSE: To examine the influence of a variety of soft contact lens (SCL) materials on the corneal endothelium, prior to and following two weeks cessation of SCL wear. METHODS: Corneal endothelial cells were examined using a CEM-530 specular microscope (Nidek, Japan). Full-time SCL wearers (n = 31 eyes) were compared to a non-contact lens (NCL) control group (n = 28 eyes) of a similar age (SCL: 20.82 ± 1.69 years, NCL: 21.14 ± 2.85 years, p = 0.58). Parameters analysed were endothelial cell density (ECD; cell/mm2), mean cell area (MCA; μ2), coefficient of variation (COV) and hexagonality (%). RESULTS: Prior to SCL cessation, two-way ANOVA testing showed significant differences between silicone hydrogel (SiH) SCL materials for the COV at 0o, with generation 2 SiH (G2SiH) wearers showing increased COV (27.67 ± 3.78) compared to generation 3 SiH (G3SiH) wearers (24.50 ± 3.73, p = 0.01). COV at the superior periphery was significantly lower in the NCL group (25.63 ± 2.79) compared to the hydrogel group (29.92 ± 6.22, p = 0.02). The MCA in the inferior periphery was also significantly higher in the NCL group (346.92 ± 36.75) compared to the hydrogel group (314.92 ± 16.57, p = 0.02). Following 14 days SCL cessation, no statistically significant differences in stability of endothelial parameters were detected between NCL and SCL material groups (all p values >0.05). CONCLUSION: SCL wear has an effect on paracentral and peripheral corneal endothelial measurements in SCL wearers compared to NCL wearers; with largest significant differences seen between NCL and hydrogel SCL wearers. Following two weeks SCL cessation, there were no significant differences in the stability of all endothelial measurements, regardless of which SCL material was worn. BACKGROUND Aoife Lloyd McKernan BSc (Hons) Optom FAOI1 , Luisa Simo Mannion DOO EU PhD2 , Veronica O'Dwyer DipOpt FAOI PhD 1 1Dublin Institute of Technology, Ireland, 2Plymouth University, United Kingdom Corneal hypoxia due to over-wear of low oxygen transmissibility (DK/t) SCLs results in endothelial polymegathism and corneal thinning 1. High DK/t SiH materials are reported to have negligible effects on the corneal endothelium 2. Hypothesis: endothelial parameters would show greater variation in a full-time low DK/t hydrogel SCL wearing group compared to a high DK/t SiH wearing group or NCL control group. Refitting previous low DK/t CL wearers with higher DK/t CLs results in reversal of hypoxia-induced endothelial changes 2. It is proposed that this reversal is linked to both the resolution of hypoxia and due to a mechanical reorganisation of the corneal endothelium following resolution of oedema-induced increased corneal thickness2. The stability of endothelial parameters in this study was examined over a two week period following cessation of SCL wear. This time period was chosen as it is the recommended SCL cessation time prior to corneal refractive surgery 3 and it has been previously demonstrated4 that the resolution of corneal and curvature and thickness following SCL cessation occurs within this time. Hypothesis: it was expected that endothelial corneal parameters in full time hydrogel SCL wearers would be more unstable after two weeks SCL wear cessation than SiH SCL wearers or NCL wearers METHODS  Inclusion criteria • Myopic prescriptions with low astigmatism ( 5 days per week for at least one year). • NCL group: no history of CL wear in the year prior

Associations with Meibomian Gland Atrophy in Daily Contact Lens Wearers.

To determine associations for contact lenses (CLs) and meibomian gland atrophy in a matched-pair study. Contact lens wearers (case) and age- and sex-matched non-contact lens (NCL) wearers with no history of CL use (control) were recruited for a multicenter study. All subjects were administered the Ocular Surface Disease Index questionnaire and a comprehensive battery of clinical tests (e.g., tear breakup time, bulbar and limbal redness, meibography, etc.) were performed. Upper and lower eyelid meibomian gland atrophy were graded with both digital meibography (percent gland atrophy) and visual meiboscore methods. Conditional logistic regression analyses were then used to determine relationships among CL use, meibomian gland atrophy, and ocular surface signs and symptoms. A total of 70 matched pairs were analyzed. The mean (± SD) age of the CL group was 30.6 (± 12.4) years, and that of the NCL group was 30.1 (± 12.2) years. The subjects were 63% female. The association between CL wear and meiboscore was not significant univariately, but the best-fitting multivariate regression model showed that higher meiboscores were associated with being a CL wearer (odds ratio [OR], 2.45) in a model that included eyelid margin erythema (OR, 0.25) and lissamine green staining (OR, 1.25). Percent gland atrophy was not associated with CL wear in regression analysis (p = 0.31). This study determined inconclusive associations with CLs and meibomian gland atrophy. This study also provided a comprehensive assessment of differences between CL and NCL wearers.

A rare case of Arthrographis kalrae keratomycosis in a non-contact lens wearer

&#x0D; Purpose: Keratomycoses secondary to Arthrographis kalrae are rarely reported. Previous cases involved patients with contact lens wear. Herein we report a rare case of severe fungal keratitis due to Arthrographis kalrae in a non-contact lens wearer.Methods: Case report.Results: A 52-year-old male presented with a left paracentral corneal ulcer with stromal infiltrates following contact with a foreign body while riding a motorbike. Initial treatment with intensive topical antibiotic drops failed. Antifungal therapy with hourly topical amphotericin B 0.15% and fluconazole 0.2%, as well as oral fluconazole was initiated. His ulcer progressed rapidly despite aggressive treatment. This led to a small, peripheral corneal perforation which was treated with corneal gluing and bandage contact lens. He also developed secondary glaucoma. Microbiological cultures of his corneal scrapings revealed Arthrographis kalrae. A single dose of subconjunctival amphotericin B 0.015% o.1mL was then given. At two months after presentation, he eventually underwent therapeutic penetrating keratoplasty (PK) for non-resolving keratomycosis. Following PK, he was maintained on topical amphotericin B 0.15%, fluconazole 0.2% and ciprofloxacin 0.3% four-hourly, together with fusidic acid ointment 2% twice daily. The graft failed three months post-transplant, albeit with no evidence of residual or recurrent infection.Conclusion: Arthrographis kalrae-related keratitis may occur in non-contact lens wearer. Management remains clinically challenging because this organism causes severe, rapidly progressive keratitis.&#x0D;

The role of domestic tap water on Acanthamoeba keratitis in non-contact lens wearers and validation of laboratory methods.

Acanthamoeba is increasingly recognized as an important cause of keratitis in non-contact lens wearers while contact lens wear is the leading risk factor for Acanthamoeba keratitis (AK). It is unlikely that the Acanthamoeba colonization is a feature which is effective only in patient's homes with infectious keratitis since the organism has been isolated from domestic tap water. Two hundred and thirty-one (231) corneal scrapings were taken from infectious keratitis cases, and four contact lens solutions and domestic tap waters were taken from 22 out of 44 AK-diagnosed patient's homes. Microscopic examination, culture, PCR, real-time PCR and DNA sequencing analyses were used for AK-diagnosed samples. The real-time PCR was the most sensitive (100 %) one among the methods used in diagnosis of AK. The 44 (19.0 %) out of 231 corneal scrapings, 4/4 (100 %) contact lens solution and 11/22 (50 %) of domestic tap water samples were found to be positive by real-time PCR for Acanthamoeba. A. griffini (T3), A. castellanii (T4) and A. jacobsi (T15) genotypes were obtained from corneal scrapings, contact lens solutions and domestic tap water samples taken from the patient's homes diagnosed with AK. The isolation of Acanthamoeba containing 6/22 (27.3 %) A. griffini (T3), 14/22 (63.6 %) A. castellanii (T4) and 2/22 (9.1 %) A. jacobsi (T15) from the domestic tap water outlets of 22 of 44 (50 %) of patient's homes revealed that is a significant source of these organisms. A. griffini (T3) and A. jacobsi (T15) genotypes have not been determined from AK cases in Turkey previously. Thus, we conclude that Acanthamoeba keratitis is associated with exposition of patients who has ocular trauma or ocular surface disease to domestic tap water in endemic or potentially endemic countries.

Axial Length Measurement: PalmScan Versus IOLMaster.

To compare axial length measurements taken on the handheld Micro Medical Devices (MMD) PalmScan with those taken with the Carl Zeiss Meditec IOLMaster. Sixty subjects had IOLMaster performed by a single operator to measure axial length in both eyes. Subjects then had axial length measurements taken by a different single operator with the MMD device. Each operator was masked to the other's results. Independent statistical analysis was performed to compare results. Sixty subjects had both eyes measured with each device for a total of 120 eyes. Subjects were categorized into 1 of 3 groups with 20 subjects each, 40 eyes in each group. Subjects in group A were wearers of overnight corneal reshaping, group B were soft lens wearers, and group C were noncontact lens wearers. Overall, the measures of axial length from IOLMaster and MMD were highly correlated (correlation = 0.93, P < 0.001, n = 120). Similarly, measures within each group between the 2 methods were highly correlated: group A (correlation = 0.94, P < 0.0001, n = 40), group B (correlation = 0.90, P < 0.0001, n = 40), and group C (correlation = 0.98, P < 0.001, n = 40). Results were highly correlated between the two devices. Data scatter plots and Bland-Altman plots were generated, showing that although there was good agreement between the methods, the MMD almost always measured the axial length smaller than the IOLMaster (median difference = 0.21 mm, mean difference ± SD = 0.26 ± 0.42 mm). The MMD is a convenient, reliable, and portable device to measure axial length. It can be used to monitor axial length in patients over time.

Involvement of Eyelid Pressure in Lid-Wiper Epitheliopathy

Objectives: To determine whether eyelid pressure is involved in the development of lid-wiper epitheliopathy (LWE).Methods: Study 1: The eyelid pressure was measured with a blepharo-tensiometer, and the degree of LWE was assessed in 79 eyes of 43 non-contact lens (CL) wearers. Study 2: The movements of the eyelids and displacement of the eyes during spontaneous blinking were photographed with a high-speed camera. The eyelid pressure was also measured in 34 normal eyes of 19 non-CL wearers who were not part of Study 1.Results: Study 1: Upper-LWE was detected in 24 of 79 eyes (30.4%), and no significant difference was detected in the eyelid pressure between any grade of upper-LWE. Lower-LWE was detected in 41 of 79 eyes (51.9%), and the eyelid pressure (27.9 ± 2.8 mmHg) in eyes with grade 3 LWE was significantly higher than that with grade 0 LWE (19.7 ± 1.3 mmHg; p < 0.05). Study 2: The lower eyelid pressure was significantly correlated with the length of the horizontal movement of the lower eyelids (p < 0.05) and also with the degree of posterior movement of the eye globe (p < 0.05).Conclusions: The higher pressure from the eyelid may be one of the causes for the development of lower-LWE.

Examining the effect of soft contact lens wear on lid margin sensitivity

Purpose: It is well documented that corneal sensitivity (CS) reduces with contact lens wear. However, little is known about the effect on lid sensitivity (LS) and how this correlates with patient symptoms, and an important marker of ocular discomfort and dry eye, lid-wiper epitheliopathy (LWE). This prospective, case control study was designed to examine LS in non-contact lens wearers (NCLW)andexperiencedhydrogel lenswearers (CLW)and todetermine whether LS correlates with signs and symptoms of dry eye. Method: 15 full time CLW (3M, 12F; mean age 26.3±9 years) and 15 age and iris matched NCLW (9M, 6F; mean age 25.2±7.7 years) were recruited from Cardiff University. The OSDI questionnaire was used to assess ocular comfort. Following assessment of LWE (graded according to Korb, 2005), CS and LSwas assessedwith a Cochet-Bonnet aesthesiometer and a 0.12mm thread. Results: Therewas no significant difference in CS or LS between CLW andNCLW (p=0.49 and p>0.05, respectively), however, there was a clear trend towards reduced upper LS in CLW compared to NCLW (median 58.00mm/g/s vs. 20.50mm/g/s, respectively). In contrast, CLW demonstrated significantly increased sensitivity of the upper tarsal conjunctiva compared to NCLW (118.00mm/g/s vs. 180.00mm/g/s, respectively; p=0.005). Small (r=−0.2) and medium(r=−0.3)non-significantnegative correlationswere found betweenOSDI scorewithupper and lower LS respectively.Medium, non-significant positive correlation was found between LWE with upper LS (r=0.4). Conclusions: CLW appears to have no significant effect on LS compared to NCLW. Small-medium negative correlations between OSDI score and LS indicate that increased LS is related to increased dry eye symptoms. Medium positive correlation between LWE and LS (that is, as LWE increases, sensitivity decreases) indicates that as friction increases, adaptation occurs resulting in reduced sensitivity. Rachel Hiscox is an optometrist and recently qualified PhD graduate from Cardiff University where she investigated the retina in cystic fibrosis.Whilst at Cardiff University Rachelwas involved in teaching in the undergraduate contact lens clinicswhere she developed an interest in the effect of contact lenses on ocular sensitivity. Rachel now works for Topcon as a Clinical Affairs Specialist.