Contact Lens & Anterior Eye - Articles in Press

Clinical performance of different care systems with silicone hydrogel contact lenses - Corrected Proof

Nancy Keir, Craig A. Woods, Kathryn Dumbleton, Lyndon Jones — 2010-03-04

Abstract: Purpose: To assess the clinical and subjective performance of a one-step hydrogen peroxide (H2O2) lens care system compared to a multi-purpose disinfecting system (MPDS) when used with silicone hydrogel (SiH) lenses.Methods: This was an eight-week, contralateral (lens type) clinical trial with a randomized, cross-over (care system) design. The H2O2 system was Clear Care ((AO Sept Plus) CIBA VISION) and the MPDS was OPTI-FREE RepleniSH (Alcon) and the SiH materials were lotrafilcon B (Air Optix; CIBA VISION) and senofilcon A (Acuvue OASYS, Johnson & Johnson Vision Care). Investigators and subjects were masked to lens care and lens type, respectively. Clinical variables and ocular health assessments were conducted at a baseline, two-week and four-week visit for each cross-over phase. Comfort, dryness and vision were rated on 0–100 scales. Wearing times and comfortable wearing times were also recorded.Results: Twenty-six subjects were enrolled: nine male, 17 female, mean age (±standard deviation) 31±12 years (range 17–59 years) and 24 subjects completed the study. Clinical variables showed no difference between solutions (all p>0.05), however one subject exhibited solution-induced corneal staining with both lens materials and the MPDS. There was no difference between solutions in subjective overall ratings of comfort, dryness or vision (p>0.05). The H2O2 resulted in longer reported comfortable wearing times than the MPDS (10.93±1.71 vs 9.84±1.47h; repeated measures ANOVA, p<0.01).Conclusions: While both lens care systems performed well with the SiH lenses used, the H2O2 resulted in a longer reported comfortable wearing time then the MPDS.

Tear film dynamics and lipid layer characteristics—Effect of age and gender - Corrected Proof

Cécile Maïssa, Michel Guillon — 2010-03-04

Abstract: Purpose: Dry eye disease is significantly more prevalent in older subjects and among them more marked in women than men. Further, it is established that the tear film dynamics of dry eye sufferers is different to that of normal. It is therefore postulated that the greater prevalence of dry eye problems with advancing age is at least in part related to poorer tear film dynamics.Methods: Tear film dynamics (non-invasive break up time) and lipid characteristics (lipid layer thickness and contamination) were assessed using the Tearscope lighting system.Results: 160 Subjects less than 45 years old and 58 subjects aged 45 years or more formed the study populations. The tear film stability was mostly influenced by age; the break up time was statistically significantly shorter for the older age group (p<0.001). The lipid layer was also significantly thinner (p=0.013) for the subjects aged 45 years or older with a very marked synergic effect of age and gender. The lipid layer of older women was significantly thinner and more contaminated than that of younger women (p=0.002 and <0.001) and of older men (p=0.034 and 0.004).Conclusions: Aging of the tear film is characterised by its destabilisation associated with significant changes in the tear lipid layer producing less protection from evaporation in the older population; the observed changes are more marked in women than in men. The findings have significant implications for the management of presbyopic dry eye sufferers, for whom decreasing evaporative problems is essential.

Tear osmolarity measurement using the TearLab™ Osmolarity System in the assessment of dry eye treatment effectiveness - Corrected Proof

Umberto Benelli, Marco Nardi, Chiara Posarelli, Timothy G. Albert — 2010-02-15

Abstract: Purpose: To evaluate the efficacy of three commercially available lubricant eye drops for the treatment of mild, dry, irritated eyes.Methods: Randomized, investigator-masked evaluation of 60 patients in which 20 patients used carboxymethylcellulose sodium (CMC), 0.5% (Cellufresh®, Allergan Inc., Irvine, CA) (group 1); 20 patients used a drop containing polyethylene glycol 400, 2.5% and sodium hyaluronate (Blink® Intensive Tears, Abbott Medical Optics Inc., Santa Ana, CA) (group 2); and 20 patients used HP Guar 0.18% (Systane®, Alcon Laboratories Inc., Ft. Worth, TX) (group 3). Study visits were at baseline and 1 month. Tests performed at both visits included Schirmer, tear-film break-up time (TBUT), visual acuity, fluorescein staining, tear osmolarity and wavefront aberrometry. Osmolarity testing was performed prior to instillation of the lubricant eye drops and then a final time 5min after instillation of the drop at both day 1 and day 30. Tear osmolarity was performed only in the right eye and only one time before and after instillation of lubricant eye drops.Results: At day 1 the mean reduction in osmolarity 5min after instillation of the lubricant eye drop was, −5.0±1.9 in group 1, −9.0±4.2 in group 2 and −5.0±2.2 in group 3. At day 30 the mean reduction in osmolarity 5min after instillation of the lubricant eye drop was, −5.6±2.3mOsm/L in group 1; −9.9±2.8mOsm/L in group 2 and −4.5±1.8mOsm/L in group 3. The differences were statistically significant between groups 1 and 2, and 2 and 3. There was a reduction of osmolarity from day 1 to day 30 but the differences were not statistically significant. We feel that after a 30-day treatment with the lubricant eye drops, the lower osmolarity values could indicate that the tear film is progressing towards a more normal osmolarity value. A future study could examine the tear osmolarity value after 60 or 90 days of usage. LogMAR best-corrected visual acuity (BCVA) results showed an improvement in group 2 compared with baseline with no change in BCVA in groups 1 and 3. There was no statistically significant change from day 1 to 1 month in TBUT, while the Schirmer test showed an improvement in all groups at 1 month.Conclusions: Assessment of tear osmolarity provides the most objective, measurable test for determining improvement in dry eye patients. The instillation of any artificial tear or lubricant eye drop should decrease the tear-film osmolarity. The results found that polyethylene glycol 400, 0.25% and sodium hyaluronate (Blink® Intensive Tears) significantly improved tear osmolarity compared with carboxymethylcellulose sodium (CMC), 0.5% (Cellufresh®) and HP Guar 0.18% (Systane®) after instillation.

Objective clinical performance of ‘comfort-enhanced’ daily disposable soft contact lenses - Corrected Proof

James S. Wolffsohn, Olivia A. Hunt, Ashock Chowdhury — 2010-02-10

Abstract: Purpose: To examine the objective clinical performance of ‘comfort-enhanced’ daily disposable contact lenses over a 16-h day.Methods: Four contact lenses (Hilafilcon B, Etafilcon A Plus, Nelfilcon A and Nelfilcon A Plus) were evaluated in an investigator masked, open label trial at the end of a week's bilateral wear. Pre-lens non-invasive tear break-up time (PL-NITBUT), tear prism height, bulbar hyperaemia and ocular surface temperature (OST) were measured with the lens in situ at 8, 12 and 16h of wear.Results: There was no difference between how many hours the lenses types were worn each day (F=0.90, p=0.44). The PL-NITBUT decreased with the duration of daily lens wear (F=32.0, p<0.001) and was more stable with Nelfilcon A Plus (F=6.00, p=0.002) than with the other lenses evaluated. Bulbar blood vessels increased in coverage (F=11.5, p<0.001) but not overall redness (F=0.0, p=0.99) with the duration of daily lens wear, but there was no difference between the lenses (p>0.05). The tear prism height decreased with the duration of daily wear (F=27.0, p<0.001) and differed between lenses (F=2.9, p=0.04). The OST decreased with the duration of lens wear (F=119.7, p<0.001) and was reduced by daily disposable lens wear (F=7.88, p<0.001), but did not differ between lenses (F=0.88, p=0.45).Conclusions: Objective measures of tear film indicated a difference between the lenses evaluated for PL-NITBUT and tear prism height, but not for wearing time or bulbar conjunctival hyperaemia. Therefore clinical benefits of daily disposable ‘comfort enhancing’ contact lenses can be measured, but challenges remain in producing contact lenses that do not compromise anterior eye physiology over the whole day.

The use of video-keratoscopy in predicting contact lens parameters for keratoconic fitting - Corrected Proof

Luigina Sorbara, Kristine Dalton — 2010-02-04

Abstract: Purpose: The purpose of this report is to demonstrate the use the video-keratoscope in determining the type and size of the cone in keratoconus and PMD patients and the final back optic zone diameter (BOZD) and total lens diameter (LD).Methods: A retrospective review of one hundred clinical records including topographic maps, of keratoconic patients (randomly selected) was performed. Cone diameter and type and final contact lens base curve and diameter were recorded.Results: The types or variations of keratoconus were determined with the use of the tangential map to be either: centred or nipple, early oval cones, moderate oval cones, severe cones or pellucid marginal degeneration (PMD). The size of the cone was dependent on the type and the stage of progression of the cone. Inventory sets for keratoconus that had progressively smaller BOZDs as the base curve or back optic zone radius (BOZR) steepened were found to fit best when prescribed for centred or nipple cones. Inventory sets or multicurve sets that had a constant BOZD with a certain lens diameter that did not vary with the BOZR were found to perform better on oval cones. Very large cones, as with PMD benefited from lenses with very large BOZDs.Conclusions: Matching the size of the BOZD (and in tandem the LD) to the size of the cone as determined with the tangential topographic map may be a useful tool in aiding in contact lens fitting to increase success.

Role of hypo-osmotic saline drops in ocular comfort during contact lens wear - Corrected Proof

Ulrike Stahl, Mark Willcox, Fiona Stapleton — 2010-02-01

Abstract: Purpose: To determine whether hypo-osmotic saline drops can improve contact lens associated discomfort and dryness by decreasing contact lens osmolality.Methods: Fifteen symptomatic subjects wore Lotrafilcon A lenses bilaterally for 6h on two different days. According to randomisation, hypo-osmotic (280mmol/kg) or hyper-osmotic (380mmol/kg) saline drops were applied four times during each day and ocular symptoms, tear film and contact lens parameters, and contact lens osmolality were assessed.Results: Sixty percent of the subjects preferred the hypo-osmotic saline drops, compared to 33%, who preferred the hyper-osmotic ones. Subjects experienced significantly less dryness and lens awareness with hypo-osmotic saline drops compared to hyper-osmotic ones (p<0.05). Using the hypo-osmotic drops, there was a trend for decreased contact lens osmolality from 379 to 343mmol/kg (p=0.06). There were no differences in lipid layer, non-invasive tear film break-up time, lens surface wettability, lens water content after wear, lens movement on eye or ocular staining and indentation between saline drops (all p>0.05). Interestingly, the difference in contact lens osmolality between drops did not reflect the osmolality difference between the two saline drops.Conclusion: Hypo-osmotic saline drops were preferred by a greater number of subjects and contact lens osmolality tended to be lower with the use of hypo-osmotic saline. Hypo-osmotic drops have the potential to decrease contact lens osmolality which in turn may help improve ocular comfort. This has possible impact on the practitioners’ choice of the lens rewetting drop recommended and the design of future lens rewetting drops.

Effect of a liposomal spray on the pre-ocular tear film - Corrected Proof

Jennifer P. Craig, Christine Purslow, Paul J. Murphy, James S.W. Wolffsohn — 2010-01-22

Abstract: Purpose: With the potential to address evaporative dry eye, a novel spray has been developed in which phospholipid liposomes are delivered to the tear film via the surface of the closed eyelid. This study evaluated the short-term effects of liposomal spray application on the lipid and stability characteristics of the pre-ocular tear film in normal eyes.Methods: Twenty-two subjects (12M, 10F) aged 35.1±7.1 years participated in this prospective, randomised, double-masked investigation in which the liposomal spray was applied to one eye, and an equal volume of saline spray (control) applied to the contralateral eye. Lipid layer grade (LLG), non-invasive tear film stability (NIBUT) and tear meniscus height (TMH) were evaluated at baseline, and at 30, 60, 90 and 135min post-application. Subjective reports of comfort were also compared.Results: Treated and control eyes were not significantly different at baseline (p>0.05). Post-application, LLG increased significantly, at 30 and 60min, only in the treated eyes (p=0.005). NIBUT also increased significantly in the treated eyes only (p<0.001), at 30, 60 and 90min. TMH did not alter significantly (p>0.05). Comfort improved relative to baseline in 46% of treated and 18% of control eyes, at 30min post-application. Of those expressing a preference in comfort between the eyes, 68% preferred the liposomal spray.Conclusions: Consistent with subjective reports of improved comfort, statistically and clinically significant improvements in lipid layer thickness and tear film stability are observed in normal eyes for ≥1h after a single application of a phospholipid liposomal spray.

Validation of the 5-Item Dry Eye Questionnaire (DEQ-5): Discrimination across self-assessed severity and aqueous tear deficient dry eye diagnoses - Corrected Proof

Robin L. Chalmers, Carolyn G. Begley, Barbara Caffery — 2010-01-22

Abstract: Purpose: To validate a subset of Dry Eye Questionnaire (DEQ) items that discriminate across self-assessed severity and various diagnoses of dry eye (DE).Methods: Subjects (n=260) in 2 studies received a clinical DE diagnosis, completed the 6-page DEQ and self-assessment of DE severity (SA-Sev). SA-Sev ratings were: 46 Severe, 107 Moderate, 77 Mild, and 46 None. Dry eye diagnoses were: 48 asymptomatic controls (C), 155 non-SS KCS, and 57 Sjögren Syndrome (SS). All DEQ items were correlated to SA-Sev by Spearman. Groups of highly correlated DEQ items were tested to discriminate SA-Sev; and the subset tested to distinguish across DE diagnosis.Results: The DEQ-5 comprises: frequency of watery eyes (r=0.48), discomfort (r=0.41), and dryness (r=0.35), and late day (PM) intensity of discomfort and dryness (r=0.42, 0.36) all significantly correlated to SA-Sev (p<0.01). Mean DEQ-5 scores by SA-Sev: Severe 14.9±2.3, Moderate 11.4±3.3, Mild 8.6±3.1 and None 2.7±3.2 (ANOVA, p<0.0001) and by DE diagnosis: C 2.7±2.9, non-SS KCS10.5±4.5 and SS14.0±3.4, differing significantly overall (Z=−8.6, p=0.000) and between diagnoses (X2=116.3, p=0.000). Watery eyes were reported primarily by non-SS KCS. Proposed screening criteria for the DEQ-5 are >6 for DE and >12 for suspected SS.Conclusions: The DEQ-5, the sum of scores for frequency and PM intensity of dryness and discomfort plus frequency of watery eyes, effectively discriminated across self-assessed severity ratings and between patients with DE diagnoses. These results indicate that DEQ-5 scores >6 suggest DE and scores >12 may indicate further testing to rule out SS–DE.

Attitudes towards contact lenses: A comparative study of teenagers and their parents - Corrected Proof

2010-01-18

Abstract: Purpose: This two-phase survey aimed to identify the beliefs and attitudes that create a barrier towards contact lens (CL) fitting among adolescents (aged 12–18 years) and their parents attending eye care practitioner clinics in Italy (phase 1) and Iberia (Spain and Portugal; phase 2). In phase 2, the sample was further focused, by limiting it to those adolescents who did not already wear CL.Methods: The extent to which CL satisfy aesthetic, visual, and practical needs and their effectiveness, safety, and comfort in the general population and in adolescents was rated by respondents on a 5-point Likert scale.Results: In phase 1, approximately one-third of adolescents (n=146) and parents (n=114) were CL wearers. Most adolescents (77.5% of 223) and parents (66.2% of 230) expressed a high interest in CL use in phase 2 despite none of the adolescents currently wearing CL. Parents, but not adolescents, perceived that CL were significantly less safe in adolescents than in the general population (p<0.05) in phases 1 and 2. Across both phases, adolescents and parents agreed that CL met an aesthetic need in adolescents (p<0.05 versus general population). Among 50% of parents (mainly mothers), significant concerns regarding CL were difficulties following instructions and taking care of the CL and potential eye damage, which, in mothers, led them to show less agreement towards CL use by the adolescent (p<0.001).Conclusions: These findings highlight an essential need for improved education on CL use in the population.

Effect of weathering and thickness on roughness of acrylic resin and ocular button - Corrected Proof

2010-01-14

Abstract: Purpose: The aim of this study was to evaluate the roughness of colorless ocular button and four brands of colorless acrylic resins designed to fabricate ocular prosthesis as a function of weathering (1008h) and different thickness (1 and 3.5mm).Materials and methods: One-hundred-and-twenty specimens were fabricated and distributed in 12 groups. The analysis was carried out by means of digital roughness meter.Results: Data were analyzed statistically by ANOVA and Tukey test at 1% significance. The results showed that there was no statistically significant difference after the weathering period. Both the Vipi Cril acrylic resin with 3.5mm in thickness and ocular button with 1mm in thickness presented the lowest roughness values (0.12Ra).Conclusion: The roughness of the acrylic resins and the ocular button was not affect by the weathering of 1008h. However, the thickness of the specimens proved to have a major influence on roughness property.

Break in microkeratome oscillating pin during LASIK flap creation - Corrected Proof

Chandrashekar Balachandran, Ioannis M. Aslanides — 2010-01-07

Abstract: We describe the case of a 40-year-old female myope who presented for bilateral LASIK. Intra-operatively, the microkeratome oscillating pin broke during flap creation resulting in the separation of the disposable blade from the motor. This resulted in an irregular flap with missing pieces. The procedure was abandoned and the macerated partial flap repositioned as best as possible. The patient recovered a BCVA of 6/7.5. The manufacturer has since reported taking corrective measures to prevent this problem in the future. This case is a reminder that despite care and maintenance by user and manufacturer, extreme and rare hardware malfunctions can occur. Furthermore, although potentially sight threatening if managed well these complications can be followed by good recovery of vision.

Twenty first century trends in silicone hydrogel contact lens fitting: An international perspective - Corrected Proof

2010-01-07

Abstract: Silicone hydrogel contact lenses were introduced into the market in 1999. To assess prescribing trends of this lens type since then, up to 1000 survey forms were sent to contact lens fitters in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA each year between 2000 and 2008. Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Analysis of returned forms revealed a rapid increase in the prescribing of silicone hydrogel lenses over the survey period. In 2008, silicone hydrogel lenses represented 36% of all soft lenses prescribed. The categorization of the majority of lenses prescribed as ‘refits’ is primarily attributed to the mass conversion of lens wearers from hydrogel to silicone hydrogel lenses. Silicone hydrogels may soon represent the majority of soft contact lenses prescribed.

A comparison of a topography-based rigid gas permeable contact lens design with a conventionally fitted lens in patients with keratoconus - Corrected Proof

Nawtej S. Bhatoa, Scott Hau, Daniel P. Ehrlich — 2010-01-06

Abstract: Purpose: To determine if a clinically comparable contact lens could be designed for patients with keratoconus utilising a corneal topographer and its contact lens design software.Methods: A total of 30 patients with keratoconus were recruited for this randomized, double-masked prospective study. Corneal topography was performed on each patient using the Orbscan II (Bausch & Lomb, NY, USA) topographer. The topographers’ Fitscan RGP fitting software was used to derive a tri-curve rigid contact lens specification. This was manufactured, and then compared by three experienced clinicians with the patients’ conventionally fitted (habitual) lens. Each aspect of contact lens fitting was graded, and each grade was weighted for kappa analysis to determine if there was any significant difference between the Fitscan-derived lens and the patients’ habitual lens.Results: Percentage agreement levels between the two fitting techniques were between 74% and 100%. Kappa values varied from below 0 to 0.60, indicating poor to moderate agreement. A slight bias towards flatter apical fitting in the Fitscan design was found in some cases of advanced keratoconus. There was no systematic bias for either fitting technique when comparing visual performance and lens comfort. A higher percentage of Fitscan-derived lenses were deemed suitable to dispense to patients, either directly or after minor parameter modification.Conclusion: This study demonstrates that a satisfactory lens design for keratoconic patients can be produced utilising a topography-based system, when compared to a patients’ conventionally fitted lens. The potential advantages of this system include simplified lens selection and reduced trial lens usage, with a reduction in patient discomfort, clinical chair-time and costs.

Current silicone hydrogel UVR blocking lenses and their associated protection factors - Corrected Proof

Karen S. DeLoss, James E. Walsh, Jan P.G. Bergmanson — 2009-12-30

Abstract: Purpose: Ultraviolet radiation (UVR) blocking contact lenses provides ocular protection factors (PF) that vary with lens thickness and the nature of the polymer dopant. This study measured the UVR PF of silicone hydrogel lenses outdoors and compares this to known methods for determining PF mathematically.Methods: Ambient measurements were taken using an UVA-B radiometer, adapted to hold the test lenses over its sensor to quantify their UVR blocking capabilities. The UVR blocking silicone hydrogel lenses tested included galyfilcon A, senofilcon A, and enfilcon A. The first UVR blocking hydrogel lens, vasurfilcon A, and a non-blocking silicone hydrogel lens, lotrafilcon B, served as a comparison. Lens transmittance at the centre and periphery was measured and PF calculated to predict signal reduction for comparison with field measurements.Results: There was a significant range of cut-off wavelengths across the lenses, ranging from 370nm for enfilcon A to 390nm for vasurfilcon A, with lotrafilcon B transmitting down to 265nm, with a 3nm shift from centre to periphery across the −3.00 D UVR blockers. The UVR reduction calculated from the transmittance data correlates well with field data, ranging from 90–98% for the UVR blockers to 13% for the non-blocker.Conclusions: The silicone hydrogel lenses showed a wide range of transmittance curves with increasing PF from centre to periphery. PF calculations work well but do not always compare precisely with measured data due to factors such as sensor spectral response and the nature of the incident solar spectrum.

Essential fatty acids for dry eye: A review - Corrected Proof

Marco Roncone, Hannah Bartlett, Frank Eperjesi — 2009-12-25

Abstract: Purpose: Dry eye is a common complaint often encountered in optometric practice. However, it is a difficult condition to treat as clinical signs do not always correlate with patient symptoms. Essential fatty acids (EFA), particularly omega-3 EFA, may be effective in dealing with the underlying causes.Methods: A literature review was carried out on the PubMed, ScienceDirect and Ovid databases. Searches included keywords such as ‘dry eye’, ‘essential fatty acids’ and ‘nutrition’ to find articles relating to the treatment of dry eye syndrome (DES) with omega-3 EFAs.Results: Omega-3 and -6 EFAs need to be consumed together within a reasonable ratio to be effective. Currently, typical diets in developed countries lack omega-3 EFA and this results in an overexposure to omega-6. Omega-3 supplementation has an anti-inflammatory effect, inhibiting creation of omega-6 prostaglandin precursors. Omega-3 EFAs also demonstrate anti-inflammatory action in the lacrimal gland preventing apoptosis of the secretory epithelial cells. Supplementation clears meibomitis, allowing a thinner, more elastic lipid layer to protect the tear film and cornea.Conclusion: Dietary supplementation of omega-3 EFA has already proven to be effective in coronary heart disease and arthritis. Safety is not a concern as it works synergistically with omega-6 in the body. Evidence suggests that supplementation with omega-3 EFA may be beneficial in the treatment and prevention of DES.

International rigid contact lens prescribing - Corrected Proof

2009-12-25

Abstract: Rigid lenses have been fitted less since the introduction of soft lenses nearly 40 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA between 2000 and 2008 facilitate an accurate characterization of the pattern of the decline of rigid lens fitting during the first decade of this century. There is a trend for rigid lenses to be utilized primarily for refitting those patients who are already successful rigid lens wearers—most typically older females being refit with higher Dk materials. Rigid lenses are generally fitted on a full-time basis (four or more days of wear per week) without a planned replacement schedule. Orthokeratology is especially popular in the Netherlands, but is seldom prescribed in the other countries surveyed.

Effect of castor oil emulsion eyedrops on tear film composition and stability - Corrected Proof

Cécile Maïssa, Michel Guillon, Peter Simmons, Joseph Vehige — 2009-12-07

Abstract: Purpose: An emulsion eyedrop containing castor oil has been shown to modify the tear film lipid layer and increase tear film stability. The primary objectives of this investigation were to measure the prevalence of castor oil in the tear fluid over time and quantify the effects on the lipid layer. A secondary objective was to quantify the initial effects on ocular symptomatology.Methods: The investigation was an open label pilot study on 5 normal and 10 dry eye subjects. A single eyedrop (Castor oil emulsion, Allergan) was instilled in each eye; the tear film appearance and composition were monitored for 4h via in vivo visualisation using the Tearscope™ and post in vivo tear samples analysis by HPLC.Results: Combined results for both normal and dry eye subjects showed that castor oil was detected up to 4h after a single eyedrop instillation and associated with an increase in the level of tear film lipid. The relative amount of various lipid families was also changed. An increase in tear lipid layer thickness was significant up to one hour post-instillation for the symptomatic sub-population. The changes in tear film characteristics were associated with significantly lower symptoms up to four hours post-instillation for the symptomatic sub-population.Conclusion: This pilot investigation showed that castor oil eyedrops achieved a residence time of at least four hours post-instillation, producing a more stable tear film and an associated significant decrease in ocular symptoms over the entire follow-up period for the symptomatic subjects.