A novel in-vitro method for assessing contact lens surface dewetting: Non-invasive keratograph dry-up time (NIK-DUT)

Purpose

This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting.

Antimicrobial efficacy of a novel povidone iodine contact lens disinfection system

Purpose

Contact lens (CL) wear is a risk factor for the acquisition of microbial keratitis. Accordingly, compliance to manufacturers’ recommended hygiene and disinfection procedures are vital to safe (CL) use. In this study we evaluated a novel povidone-iodine (PI) (CL) disinfection system (cleadew, Ophtecs Corporation, Japan) against a range of bacterial, fungal and Acanthamoeba.

Clinical outcomes of a novel presbyopia-correcting soft contact lens with a small aperture

PurposeTo investigate the efficacy and safety of a newly developed pinhole soft contact lens (Eyelike Pinhole II; Koryo Eyetech Co. Ltd.) for presbyopia correction.MethodsThis prospective clinical study enrolled 29 patients with presbyopia between October 2018 and December 2018. All participants wore the Eyelike Pinhole II in the non-dominant eye for >3 h/day for a period of 1 week. Binocular and monocular uncorrected near visual acuities, distance-corrected near visual acuity (DCNVA), uncorrected distance visual acuity, and corrected distance visual acuity (CDVA) were measured before and after the intervention. All visual acuities were measured in logarithm of the minimal angle of resolution (logMAR) units. In addition, binocular defocus curves were generated, and contrast sensitivity values were obtained under photopic and mesopic conditions before and after lens wear.ResultsThe mean DCNVA of the treated eye and the mean binocular DCNVA improved from 0.34 ± 0.12 to 0.15 ± 0.14 (P < 0.001) and 0.31 ± 0.13 to 0.11 ± 0.10 (P < 0.001) logMAR, respectively, after pinhole contact lens wear. Although the mean CDVA of the treated eye deteriorated from −0.04 ± 0.05 to 0.02 ± 0.11 logMAR (P = 0.015), there was no significant change in the mean binocular CDVA (P = 0.79). The binocular defocus curve showed a significant improvement from −5.0 dioptres (D) to −1.0 D after pinhole contact lens wear.ConclusionsThe newly developed Eyelike Pinhole II soft contact lens showed safe and effective outcomes; thus, it could be a promising option for the treatment of presbyopia.     

Microbiocidal characterization of a novel povidone-iodine based rigid contact lens disinfecting solution

This study investigated the efficacy of a novel povidone-iodine based disinfection solution for rigid gas permeable (RGP) lenses compared to three other currently available multipurpose and hydrogen peroxide solutions. Bactericidal and fungicidal activities were assessed using ISO 14729 reference methods, whilst amoebicidal properties were evaluated using an automated viability counter. All solutions were also assessed for long term storage stability over a 3-month period.The FDA guidelines were adequately achieved by all solutions tested and 3-month storage did not affect their activity against bacterial and fungal agents. Activity against Acanthamoeba castellani trophozoites reached 1-log reduction for the povidone-iodine solution and approached this level for the remaining solutions. Activity against cysts was somewhat reduced and ranged from 78 to 86% reduction in viability.A povidone-iodine based solution, which may offer advantages as resistance to this agent has not been demonstrated and it lacks toxicity, provided equivalent antimicrobial activity to other RGP solutions.     

Exploring microwave irradiation as a method to disinfect contact lens cases

PurposeBiofilm formation caused by infrequent contact lens case replacement and the ineffectiveness of multi-purpose solutions (MPS) on biofilm removal is associated with high rates of bacterial keratitis infections. This study demonstrated biofilm elimination from the contact lens case by microwave irradiation.MethodsStaphylococcus aureus biofilms indicative of 3–9 months of contact wear were cultured in contact lens cases and visualized with crystal violet (CV) staining. Biofilms in contact cases were then exposed to four treatment regimens: No treatment (n = 8), 45 s microwave irradiation (n = 8), tap water (n = 6), and MPS (n = 9). Bacterial survival was assessed by colony forming unit (CFU) assay using streak dilutions.ResultsVisualization of the biofilms through CV staining revealed that biofilms coalesce between ribs of the contact case. In 5/8 cases no CFU were cultivated from the case after treatment with microwave irradiation. In tap water and MPS the first dilution averaged 6 ± 2 and 31 ± 13 CFUs per plate, respectively, while microwave irradiation averaged < 1 CFU per plate. In Dilution 2, the average reduced to 0.7 ± 0.7 and 6 ± 5 CFUs per plate for tap water and MPS, respectively, while microwave irradiation had 0 CFUs in Dilution 2.ConclusionBiofilms that coalesce between the ribs of the contact case pose a threat because this area is difficult to thoroughly scrub and could act as a basis for infection through fouling of contact lenses. Of the four treatment regimens, microwave irradiation displayed the most consistent and highest rate of bacterial eradication. Tap water was less effective compared to microwave irradiation, and poses other harmful side effects, but greatly reduced CFU count compared to no treatment. MPS displayed the poorest bacterial eradication of the treatments. Thus, microwave irradiation is worth further investigation as a viable in-home disinfecting option.     

The impact of contact lens wear on ocular surface mucins using a novel clinical fluorescence imaging system

PurposeFluorescein-labelled wheat germ agglutinin (F-WGA) acts as a marker for ocular surface mucins. This clinical study sought to investigate whether the degree of F-WGA fluorescence observed at the ocular surface differed between symptomatic contact lens wearers, asymptomatic contact lens wearers and non-contact lens wearers, using a novel imaging system.MethodsTwenty-five participants (10 symptomatic contact lens wearers, 10 asymptomatic contact lens wearers and 5 non-contact lens wearers) attended a single study visit. Photographs of the cornea, bulbar and tarsal conjunctiva were captured following application of F-WGA solution.ResultsThe imaging system captured high-resolution images of F-WGA fluorescence at the ocular surface. The degree of fluorescence differed between the ocular surface regions (p < 0.001). A significant difference in fluorescence was observed between participant groups for the cornea (p = 0.01), with both the symptomatic and asymptomatic contact lens wearers showing lower fluorescence than the non-lens wearers. F-WGA associated fluorescence appeared diminished in the lid wiper region of the symptomatic lens wearers, compared to the asymptomatic group (p = 0.025).ConclusionThe use of F-WGA as a clinical marker for ocular surface mucins allows an improved understanding of their distribution across the ocular surface. Contact lens wear appears to negatively impact mucin density across the ocular surface, with the most marked effect on the cornea. F-WGA fluorescence appeared diminished in the lid wiper region for the symptomatic contact lens wearing group, indicating that mechanical interaction in this region may play a role in the aetiology of contact lens discomfort. Given the ability of F-WGA to disclose mucin distribution across the ocular surface it is likely to be a key clinical tool in furthering our understanding of (i) the aetiology of contact lens related discomfort, (ii) contact lens designs/materials to minimise interaction with the ocular surface and (iii) dry eye disease and other ocular surface diseases.     

A study of contact lens compliance in a non-clinical setting

PurposeTo evaluate soft contact lens replacement, overnight (ON) wear, and contact lens case compliance in a non-clinical sample.MethodsSubjects (n = 297) were recruited at the Center for Science and Industry (COSI) in Columbus, Ohio. Adult (≥ 18 years) soft contact lens wearers completed a survey about contact lens replacement, ON contact lens wear, and contact lens case replacement habits.ResultsTwo-week replacement lenses (according to the manufacturer’s replacement schedule [MRS]) were most common (45.5%), followed by monthly (34.3%) and daily replacement (20.2%). Non-compliance with replacement schedule was reported in 38.7% of subjects. Age (p = 0.02), years of lens wear (p = 0.02), and MRS (p <0.0001) affected replacement compliance. Post-hoc analysis showed daily replacement wearers were more compliant than two-week (p <0.0001) and monthly (p <0.0001) replacement wearers with prescribed lens replacement. Non-compliance with prescribed ON wear was reported in 23.9% of subjects. Subjects who were non-compliant with lens replacement were more likely to be non-compliant with ON wear (p = 0.02) and had worn contact lenses for less time (p = 0.02). Of the subjects who used contact lens cases, 74.6% were unsure when they should replace their case. Frequency of case replacement was not associated with age (p = 0.5), gender (p = 0.5), years of contact lens wear (p = 0.7), MRS (p = 0.4), replacement compliance (p = 0.3), or ON wear compliance (p = 0.7).ConclusionsDaily replacement wearers were most likely to be compliant with contact lens replacement, but all subjects, including daily replacement wearers, had similar ON wear non-compliance. Non-compliant lens replacement was associated with non-compliant ON wear, but contact lens case replacement was not related to either compliance category. The majority of subjects had no knowledge of proper contact lens case replacement, despite compliance in other categories.     

Videokeratoscopic assessment of silicone hydrogel contact lens wettability using a new in-vitro method

PurposeThe aim of the study was to assess the surface wettability of new-generation silicone hydrogel (SiH) contact lenses (CLs) videokeratoscopically using a new in-vitro method under office conditions.MethodVideokeratoscopic methodology was used to compare time-dependent CL wettability on an in-vitro cornea model. The model cornea was a polished chrome surface coating a Teflon form. It was prepared with a base curve of 8.7 mm and a diameter of 15 mm. Laboratory temperature and humidity were controlled. Before and after placing CLs on the on the model cornea, Bausch + Lomb Biotrue® multi-purpose solution (MPS) was dropped to simulate the pre-lens and post-lens film layer. Fanfilcon A, Senofilcon A, Samfilcon A, and Lotrafilcon B CLs with -3.00D were used, and images were taken with the videokeratoscopic method for testing. In the control group, the same procedure was performed without placing CLs. The images of CLs at 0, 60, 90, 120, 150, and 180 s were taken. Distortions and gaps seen in rings were recorded. The areas in rings were calculated in pixels using İmageJ.ResultsWhen CLs were examined, statistical differences were found among average pixel values (p < 0,001). The average pixel value was 131877.4 in the Samfilcon group, 116125.5 in the Senofilcon group, 137893.2 in the Fanfilcon group, 125578.3 in the Lotrafilcon group, and 124984.6 in the control group. No difference was found between the average values of the Lotrafilcon group and the control group. Differences were found between the average values of all other groups.DiscussionThe results obtained showed that videokeratoscopy was an effective method for in-vitro testing of CL wettability. It was found that SiH lenses displayed different performance under office conditions depending on materials and technologies used for wetting the lens surface. It was shown that lens surface wettability could be measured with a repeatable and new method when the factors affecting surface wetness and image quality were ruled out.     

The effect of rebamipide ophthalmic suspension on ocular surface mucins in soft contact lens wearers

Purpose

To evaluate the changes in ocular surface mucins with 2%rebamipide ophthalmic suspension treatment in soft contact lens (SCL) wearers. Rebamipide suspension is a mucin secretagogue approved for the treatment of dry eye syndrome in Japan. In this study, the fluorescence intensity of wheat germ agglutinin conjugate of fluorescein (F-WGA) was used as a marker of membrane-associated mucins, and sialic acid concentration in tear fluids as a marker of secreted mucins.

Novel in vitro method to determine pre-lens tear break-up time of hydrogel and silicone hydrogel contact lenses

PurposeTo develop an in vitro model to determine pre-lens non-invasive break-up time (NIBUT) and to subsequently use this method to compare the NIBUT over contemporary daily disposable (DD) contact lenses (CL).MethodsThree silicone hydrogel (SH) and two conventional hydrogel (CH) DD CLs were incubated in an artificial tear solution (ATS). A model blink cell (MBC) was utilised to mimic intermittent air exposure. CLs were repeatedly submerged for 3 seconds (s) and exposed to air for 10 s over periods of 2, 6, 12, and 16 hours (h). NIBUTs (n = 4) were determined out of the blister pack (T₀) and at the end of each incubation period.ResultsOverall, nesofilcon A showed the longest NIBUTs (p < 0.001). At T₀, CHs revealed significantly longer NIBUTs (p ≤ 0.001) than SHs. After 2 h, nesofilcon A showed the longest NIBUT, however, this was only statistically significant compared with delefilcon A (p ≤ 0.001). After 6 h, nesofilcon A NIBUT was significantly longer than all other CLs (p ≤ 0.001). Etafilcon A showed a significantly longer NIBUT (p ≤ 0.001) after 12 h and delefilcon A had the longest NIBUT (p ≤ 0.001) after 16 h. Statistically significant (p ≤ 0.05) changes of NIBUT within the lens materials varied between time points. After 16 h, all CLs showed significant reductions in NIBUTs (p ≤ 0.001) in comparison to T₀.ConclusionNIBUT values reduced gradually over time and varying levels of deposition impacted measured pre-lens NIBUTs. While NIBUT of CH materials are longer immediately out of the blister pack, after tear film exposure, the NIBUTs obtained using this methodology became very similar.     

Long-term changes in the ocular surface during orthokeratology lens wear and their correlations with ocular discomfort symptoms

PurposeTo evaluate the changes in ocular surface parameters during orthokeratology lens wear and determine their correlations with ocular discomfort symptoms.MethodsFifty individuals were enrolled in this prospective pilot study. Clinical evaluation of the ocular surface included the ocular surface disease index, slit-lamp examination, Keratograph 5M, optical quality analysis system, and corneal staining. After baseline examinations, clinical tests were performed at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months after orthokeratology lens wear. Correlations between ocular discomfort symptoms and signs of ocular discomfort were evaluated.ResultsOverall ocular surface disease index score and two subscale scores (ocular symptoms and vision-related function) significantly increased at the 3-month visit (P < 0.05), and decreased to levels close to baseline at the12-month visit (P > 0.05). The basic objective scatter index and the mean tear film objective scatter index increased, peaking at 3-month visit (P < 0.05) and gradually decreased thereafter. The modulation transfer function cut-off significantly decreased at the 3-month visit (P < 0.05). During the 12-month study period, the overall ocular surface disease index score and vision-related function score were significantly and positively correlated with the basic objective scatter index and mean tear film objective scatter index (P < 0.05). After 1 week of lens wear, Grade 1 corneal staining increased to 16.4 %, mostly involving the central and inferior cornea.ConclusionsOrthokeratology lens wear increased ocular discomfort symptoms and decreased the function of tear film, mainly within 3 months of lens wear. Tear-related visual function parameters were correlated with ocular discomfort. A new parameter, tear film objective scatter index, measured with the optical quality analysis system, was more sensitive in detecting the quality and stability of tear film than traditional indicators.     

The ability of the Contact Lens Dry Eye Questionnaire (CLDEQ)-8 to detect ocular surface alterations in contact lens wearers

PurposeTo study whether some ocular surface alterations could be associated with contact lens (CL) wearers suffering from CL discomfort (CLD) detected using the Contact Lens Dry Eye Questionnaire (CLDEQ)-8.MethodsForty-one soft CL wearers further classified into symptomatic CL wearers (SCLW) and asymptomatic CL wearers (ACLW) by the CLDEQ-8, and 20 non CL wearers (NCLW) were included. Tear osmolarity, slit-lamp biomicroscopy findings, tear film break-up time, corneal and conjunctival staining, and Schirmer test were performed 24 h after CL removal. Data were compared among groups using the analysis of variance and the Student t-test or the Kruskal-Wallis H and the Mann-Whitney U tests, applying the Bonferroni correction. Correlations between the CLDEQ-8 and the clinical signs were performed using the Spearman correlation coefficient.ResultsTwenty-four SCLW, 17 ACLW and 20 NCLW were recruited. There were significant differences among groups for tear osmolarity (p < 0.001), limbal hyperaemia (p = 0.014), and tarsal hyperaemia (p = 0.031). Pairwise comparisons revealed that SCLW and ACLW had higher tear osmolarity (p < 0.003, both comparisons) and limbal hyperaemia (p = 0.027 and p = 0.048, respectively) than NCLW. Moreover, SCLW had higher tarsal hyperaemia (p = 0.030) than NCLW. No significant correlations were found (p > 0.05).ConclusionThe CLDEQ-8 was ineffective to detect clinical alterations between SCLW and ACLW; therefore, the use of questionnaires alone remains being the best approach to detect CLD. The role of the tarsal conjunctiva in the development of CLD should be analyzed in future studies.     

Variation in optic zone radii of a contact lens during manufacturing and the effects of temperature on this variation

There is little information in the literature on the causes of variation in the optic zone radii of a contact lens and the effects of temperature on this variation. In this study, the lathe cutting method of producing contact lenses was reviewed. The cause of the variation in the back optic zone radius was then identified as change in the operating condition from that of the calibrating one. Also, using finite element and theoretical methods, it was found that the effect of an increase in lens blank temperature is to make the back optic zone radius obtained steeper than that required, and this effect was verified experimentally.     

Effect of material and care system combination on subclinical inflammation of the ocular surface in soft contact lens wear

PurposeTo investigate the ocular subclinical inflammatory response in two soft contact lens materials when used in combination with two different care systems (‘solutions’).MethodsFifteen established soft contact lens wearers wore each of two lenses: Acuvue® 2 (CH) and Acuvue® Oasys® (SiH) or no lenses in random sequence for one week. Two care systems were used: a peroxide system: Oxysept 1 Step® (P) for the right lens and Opti-Free® Replenish® (MPS) for the left lens. After one week of lens/no lens wear, in vivo confocal microscopy (IVCM) of corneal and conjunctival regions was carried out. Density of presumed dendritic cells (DC) and ‘white spots’ (WS) were quantified. Impression cytology of the bulbar and upper eyelid margin conjunctivae was carried out and samples were analysed for CD45+, CD3+ and CD11c+ cells.ResultsThe SiH + MPS combination showed a greater inflammatory response compared to SiH + P in seven out of 12 parameters investigated (p < 0.05). The remaining five were not statistically different between the two solutions. The converse was found for the CH lens, with four of the 12 parameters showing a greater response with the P solution compared to the MPS (p < 0.05).ConclusionThis study suggests that the SiH lens investigated demonstrated an upregulated response when used with a MPS compared to a P solution whereas the converse is true for the CH lens which showed a reduced response when used with a MPS compared to a P solution. This finding aids in the understanding of the biological underpinnings of manifest corneal inflammatory events during contact lens wear.     

Performance and predictability of a new large diameter contact lens design in keratoconic corneae

ObjectivesTo evaluate the clinical performance and predictability using corneal topography in the fitting of a new large-diameter rigid gas permeable (RGP) contact lens design in eyes with keratoconus (KCN).MethodsThis study presents a review of eyes fitted with Alexa ES lenses for nonsurgical optimisation of visual correction. Anterior steep simulated keratometry (sim-K steep), corneal diameter (HVID), the Curvature at the apex in diopters (Cc), and distance from the corneal apex to the centre of the cornea (Lc) in millimetres derived from the Cone Location and Magnitude Index (CLMI) were recorded. Visual acuity, mean wearing time, final sagittal depth and adverse events were also recorded. Correlations between topographic indices and base curve were evaluated using the Pearson correlation coefficient.ResultsForty-six eyes from 26 patients (19 males/ 7 females) were included. Mean visual acuity improved from 0.49 ± 0.32 with glasses, to -0.02 ± 0.10 with the contact lens. The mean daily wear time was 12.19 ± 1.96 hours. No complications were detected in 95.65% of the eyes [95% CI (83.9%-99.2%)] but two episodes of non-infectious keratitis. The average sagittal depth of the lenses fitted was 0.425 ± 0.15 mm, and it was positively correlated with the Cc value (r² = 0.66, p< 0.0001, n=46) derived from the CLMI index of the pre-fitting topography.ConclusionsCorneoscleral RGP contact lenses are a safe, and effective alternative for managing KCN patients to corneal lenses. Also, clinical data derived from the corneal topography could be used to help to decide the first diagnostic lens to be assessed, easing the overall fitting process.     

Prevalence of contact lens related complications in a tertiary eye centre in India

Aim

To determine the prevalence of contact lens related complications in a tertiary eye care centre in India.

Methods

A retrospective review of the charts of 1255 patients who visited our contact lens clinic during 2001-2004 was conducted. The inclusion criteria included patients of at least 18 years of age, having refractive errors and keratoconus. Exclusion criteria included previous corneal surgeries and pediatric patients. 190 subjects with lens related complications were identified from among 923 patients who were using lenses.

Results

The prevalence of contact lens complications was 20.58%. Females with complications were more common (59.47%). The complications were more common in students. The most common complications were contact lens induced papillary conjunctivitis (CLPC) (6.39%), corneal vascularisation (4%), and superficial punctate keratitis (SPK) (3.5%). The total complications were less prevalent in patients wearing rigid gas permeable (RGP) lenses as compared to soft contact lenses. Infectious keratitis was noted in 8 eyes. Pseudomonas aeuroginosa was the most common organism isolated. The average daily wear with RGP lenses was 11.04 ± 3.7 h and 10.96 ± 3 h with soft contact lens. The highest number of complications was noted in 47.89% patients who were wearing lenses for excess of 11 h. The number of patients with complications arising due to sleeping with the lenses was 74 (38.95%).

Conclusion

Prevalence of contact lens complications was more in soft contact lens wearers compared to RGP wearers. CLPC was the most common complication followed by vascularisation and SPK.     

Optimizing correction of coma aberration in keratoconus with a novel soft contact lens

PurposeTo report on a second-generation prototype contact lens (modified lens) with enhanced optics to correct coma aberration and compare its performance with that of the prototype contact lens (conventional lens) used to optimise correction of coma aberration in keratoconus (KC).MethodsBoth lenses were designed as a set of standardised soft contact lenses (SCLs) with asymmetric powers along the posterior surface. The modified lens differs from the conventional lens in that the optical zone is decentred superiorly by 0.7 mm. The on-eye performance was compared between the SCLs and no-lens wearing in terms of manifest refraction, corrected distance visual acuity (CDVA), ocular aberrations, subjective quality of vision, and on-eye lens position relative to the pupil.ResultsThirty-four KC eyes were included. SCLs significantly decreased coma aberration compared to no-lens wear (none, 0.68 ± 0.27 μm; conventional lens, 0.37 ± 0.28 μm; modified lens, 0.19 ± 0.15 μm; P < 0.001), with the reduction in coma aberration being significantly greater with the modified lens than with the conventional lens (P = 0.018). No significant difference in manifest refraction or CDVA was found among the three conditions. Quality of vision was significantly better with the modified lens than with no SCL wear (P < 0.05) but no differences were found between the SCLs. The on-eye optical center position relative to the pupil was closer to the pupil centre using the modified lens than the conventional lens (P < 0.001).ConclusionOptimisation of the location of the optical zone in a standardised asymmetric SCL improves correction of coma aberrations and on-eye optical centration.     

The impact of lens care solutions on corneal epithelial changes during daily silicone hydrogel contact lens wear as measured by in vivo confocal microscopy

Purpose

To assess corneal epithelial microstructure via confocal microscopy and determine if cellular changes are associated with lens care solutions during daily wear of silicone hydrogel contact lenses.