Corneal,Conjunctival effects and blood flow changes related to silicone hydrogel lens wear and their correlations with end of day comfort

Purpose

First, to examine how wearing high and low modulus lenses with two different base curves affected lens fit, and the corneal tissue and bulbar conjunctival vascular tissue (bulbar redness and blood velocity). Secondly, to quantify the associations between these baseline and outcome variables and the third purpose was to correlate these variables with end of day comfort.

The influence of lens care systems on eyelid tissue changes during silicone hydrogel contact lens wear

Purpose

To compare the effects of a hydrogen peroxide (H₂O₂)-based lens care solution and a polyhexamethylene biguanide (PHMB) multi-purpose solution on the eyelids when used with silicone hydrogel (SiHy) contact lenses.

Compatibility of phospholipid liposomal spray with silicone hydrogel contact lens wear

Purpose

To assess the effects of two weeks of regular phospholipid liposomal spray application on lipid layer grade, tear film stability, subjective comfort, visual acuity, and lipid deposition in silicone hydrogel contact lens wearers.

A silicone hydrogel contact lens after 7 years of continuous wear

PurposeTo report an unusual case with a bandage silicone hydrogel lens that was applied over cyanoacrylate glue application for corneal perforation.DesignRetrospective, interventional case report.MethodsA 67-year-old woman with a history of corneal trauma experienced spontaneous corneal perforation in her left eye. Upon arrival, her anterior chamber was flat and Seidel test was positive. After initial treatment with cyanoacrylate adhesive and a bandage silicone hydrogel contact lens, there was no leakage and the anterior chamber was formed at the follow-up period. She was started topical antibiotics.ResultsAfter 7 years, she came back with the complaint of permanent redness in her left eye with the same silicone hydrogel lens in her eye.ConclusionsCorneal healing may occur under cyanoacrylate adhesive glue with therapeutic contact lenses and with proper antibiotic application. Silicone hydrogel contact lenses exhibit good efficacy and safety when utilized as a continuous wear therapeutic lens with antibiotics.     

The relationship between compliance with lens replacement and contact lens-related problems in silicone hydrogel wearers

Purpose

To evaluate the relationship between compliance with replacement frequency (RF) and contact lens (CL)-related problems in silicone hydrogel (SiHy) wearers.

Methods

501 SiHy wearers from seven optometry offices completed surveys regarding their lens wear and any CL related problems which they may have experienced in the preceding 12 months. File review was subsequently conducted at their optometry offices to confirm the information provided.

Results

49% of respondents were wearing 2-week replacement (2WR) and 51% 1-month replacement (1MR) SiHy lenses. 67% wore their lenses for longer than the manufacturers’ recommended RF (MRRF) and 60% for longer than their optometrist's recommended RF (ORRF). The mean RF was 2.6× the MRRF for 2WR and 1.5× for 1MR wearers (p < 0.001) with median values of 31 and 37 days, respectively. Twenty-three percent reported signs or symptoms consistent with potential complications relating to CL wear. This rate was significantly higher for wearers who were non-compliant with the ORRF than compliant wearers (26% versus 18%, p = 0.028). It was also higher for those multipurpose solution users who reported never/almost never rubbing and rinsing their lenses when compared with those who did this every night (29% versus 17%, p = 0.007).

Conclusions

Two thirds of the SiHy wearers did not comply with the MRRF and 2WR wearers stretched the replacement interval of their lenses to a greater degree than 1MR wearers. Failing to replace lenses when recommended and failing to rub and rinse lenses were associated with a higher rate of patient-reported CL problems.     

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.

Initial comfort of lotrafilcon A silicone hydrogel contact lenses versus etafilcon A contact lenses for extended wear.

PURPOSE: To compare the initial comfort afforded by silicone hydrogel lenses (lotrafilcon A) versus the comfort afforded by conventional hydrogel lenses (etafilcon A) in extended wear (EW). DESIGN: Prospective, double-masked and randomized controlled trial. METHODS: Lotrafilcon A and etafilcon A contact lenses were eye randomly fitted on an EW basis for 7 days and nights in 20 subjects. A forced-choice subject preference questionnaire was made. Subjects were comfort, dryness, red eye and visual quality after night wear and at the end of the day. Subjective scored satisfaction (scale: 1-5) and lens preference were assessed. RESULTS: Lotrafilcon A proved more comfortable after night wear (60%, CI95% 38-82%) and at the end of the day (70%, CI95% 49-90%) than etafilcon A after night wear (10%, CI95% 0-23%, P<0.05) and at the end of the day (20%, CI95% 2-38%, P<0.05). The feeling of dryness was more marked with etafilcon A after night wear (50%, CI95% 27-72%) and at the end of the day (50%, CI95% 27-72%) than it was with lotrafilcon A (15%, CI95% 0%-31%) after night wear (P>0.05) and at the end of the day (25%, CI95% 5%-44%, P<0.05). General satisfaction with the lotrafilcon A lens was 3.65 points (CI95% 3-4.2) and with etafilcon A 2.95 points (CI95% 2.5-3.3, P<0.05). Eighty percent (CI95% 62%-98%) of subjects preferred lotrafilcon A (P<0.05) for EW. CONCLUSIONS: In EW, lotrafilcon A contact lenses were more comfortable and led to less dryness after night wear and at the end of the day than etafilcon A contact lenses.     

Corneal epithelial thickness and corneal curvature changes during the day: The effects of daily disposable contact lens wear

PurposeTo evaluate the changes in corneal epithelial thickness and corneal anterior and posterior curvatures during the day, and the effect of wearing daily disposable soft contact lenses.MethodsThirty-two healthy volunteers were enrolled in a randomized crossover study. At the baseline visit, corneal and epithelial thickness maps (OCT; Optovue, Inc., Fremont, CA, USA) and keratometric measurements (Pentacam, Oculus, GmbH, Germany) were performed in the morning and in the afternoon (8 hours after). Then, each subject was fitted with the following brands of daily disposable contact lenses in random order: Dailies Total 1 (Delefilcon A), Dailies Aqua Comfort (Nelfilcon A), TruEye (Narafilcon A) and Biotrue Oneday (Nesofilcon A) on different days. All fitted lenses had a power of −3.00 diopters (D). Measurements were repeated before putting the contact lens on and after an-eight-hour contact lens wear.ResultsWith no lens wear, the anterior topographic indices showed significant steepening [Kflat: p < 0.0001; Ksteep: p < 0.0001 and maximum keratometry value (Kmax): p = 0.04] and the corneal thickness significantly decreased in the central and temporal portion of the cornea in the afternoon. There were no significant changes in the posterior topographical indices and corneal epithelial thickness. With contact lens wear, no significant change occurred in the corneal and epithelial thickness, and the anterior and posterior curvatures during the day (all p values >0.05). There was no statistically significant difference in the epithelial thickness among the groups wearing different contact lens types (p > 0.05).ConclusionsAnterior corneal topographic indices steepen depending on the natural diurnal variations. Daily wear of soft contact lenses appears to mask this steepening. The corneal epithelial thickness is not affected by daily disposable soft contact lenses.     

Corneal shape changes induced by first and second generation silicone hydrogel contact lenses in daily wear

Purpose

To compare the corneal topographical changes induced by two first and second generation silicone-hydrogel (SiH) contact lenses after 3 months of daily wear (DW).

Methods

Prospective, consecutive case-series in which patients wore one of 3 different contact lenses (either the first generation SiH Focus Night & Day, the second generation SiH Acuvue Oasys or the monthly disposable Soflens 38 hydrogel lens as control group) on a DW basis for 3 months. Over-refraction, visual acuity, mean keratometry, corneal astigmatism, corneal eccentricity, superficial regularity and superficial asymmetry indices were monitored over the 3-month period.

Results

Nineteen eyes of 10 patients completed the study. Seven Focus Night & Day, 7 Acuvue Oasys and 5 Soflens 38 contact lenses were fitted. There were no significant changes between any of the parameters measured at the 3-month visit in any of the SiH groups (non-parametric Wilcoxon test, p > 0.05). However, the control group (Soflens 38) showed statistically significant changes regarding mean keratometry, corneal astigmatism and corneal eccentricity (p < 0.05). Three patients wearing the first generation SiH showed adverse events of different degree related to their high modulus of elasticity.

Conclusions

After 3 months of DW, wearers of first and second generation SiH lenses showed greater corneal stability than hydrogel monthly disposable contact lenses users regarding commonly used topographic corneal shape indices. However, complications related to the mechanical properties of first generation SiH were seen in three patients in the follow-up time.     

Ocular physiology and comfort in neophyte subjects fitted with daily disposable silicone hydrogel contact lenses

PurposeTo evaluate the performance of a silicone hydrogel daily disposable lens in neophyte subjects over 12 months.MethodsSeventy four subjects with no previous contact lens experience were randomised to wear narafilcon A (1 DAY ACUVUE^® TruEye™) lenses (LW group) or to wear no contact lenses (NLW group) for 12 months. Biomicroscopy (performed by a masked investigator), visual acuity and subjective response scores were recorded at an initial visit and six follow-up visits, in addition to lens fit and surface evaluation for the LW group. Comfort was recorded with SMS messaging.ResultsFifteen of the LW group discontinued before the end of the study, compared with six of the NLW group. Measured visual acuity was about half a line better for the NLW group as these subjects were provided with their full sphero-cylindrical over-refraction, compared to the LW group in their best spherical corrected contact lenses; subjective scores for vision were similar for the two groups. Bulbar conjunctival hyperaemia, limbal hyperaemia, corneal staining, conjunctival staining and papillary conjunctivitis were clinically equivalent for the two groups whereas conjunctival staining was higher in the LW group. Comfort scores assessed by SMS were equivalent for the LW and NLW groups; there was a measurable improvement in comfort during the first month of wear for the LW group.ConclusionThis work has demonstrated that modern soft lenses (narafilcon A daily disposable silicone hydrogel lenses) offer an excellent, comfortable form of vision correction, and are able to exhibit minimal alterations to ocular physiology.     

The association of comfort and vision in soft toric contact lens wear

PurposeThis work set out to investigate if there was an association between subjective comfort and both subjective and measured vision during the use of contemporary daily disposable soft toric contact lenses.MethodsThirty-eight habitual soft contact lens wearers wore each of three daily disposable toric lenses for one week in a prospective, crossover, randomised, single-masked study. The following clinical measures were recorded at dispensing and follow-up visits: biomicroscopy scores, lens fitting (including rotation and rotational stability), high and low contrast visual acuity, subjective vision quality and subjective ocular surface comfort. Subjective scores were collected using 0–10 numerical grading scales. Comfort scores were analysed using a linear regression model with age, sex, visit, phase of crossover (‘phase’), lens type, lens rotation, lens rotational stability, visual acuity, cylinder power and subjective vision quality as factors of interest and then refined using backward stepwise regression.ResultsThirty six participants (31.1 ± 13.5 years) completed the study. Comfort scores were found to be associated with subjective vision quality (F = 127.0 ; p < 0.0001), phase (F = 7.2; p = 0.001) and lens type (F = 4.9; p = 0.009). Greater comfort scores were observed with greater subjective vision quality scores. Visual acuity was not statistically significant in the model.ConclusionThis work suggests that symptoms of ocular discomfort may be more intense if there is also perceived visual compromise in daily disposable soft toric lenses. There was a stronger positive correlation between comfort and subjective vision quality compared with comfort and measured visual acuity.     

In vitro evaluation of the dehydration characteristics of silicone hydrogel and conventional hydrogel contact lens materials.

PURPOSE: This study investigated the in vitro dehydration performance of silicone hydrogel and conventional hydrogel contact lens materials. METHODS: In vitro dehydration was assessed using a gravimetric method. The mass loss over time of Focus Night&Day, PureVision, Optima, Acuvue and Proclear Compatibles was measured as the ambient temperature increased from room temperature to 34 degrees C under varying airflow and humidity conditions. RESULTS: Dehydration data demonstrated a typical ogival form. The results were best fitted with a double exponential, non-linear regression model, which accounted for at least 99% of the variance. Regardless of material, increased airflow had a greater impact on dehydration rate than increased humidity (P<0.05). Relative dehydration amounts were strongly correlated with initial water content (r(2)=0.92), with higher water content materials dehydrating to a greater extent. CONCLUSIONS: In vitro dehydration studies of conventional and novel silicone-containing hydrogel materials indicated that evaporation rates from materials are predominantly water content related, with only subtle differences between materials of similar water contents being seen. Environmental conditions have a significant impact on in vitro dehydration, with increased airflow having a greater impact than reduced humidity on increasing dehydration rates. In vitro dehydration is closely related to bulk water diffusion rates and, as a result of their low water content, silicone-containing hydrogel materials exhibit low levels of dehydration compared with high water content hydrogel contact lens materials. Further, in vivo studies are necessary to see if the in vitro dehydration behaviour of silicone hydrogel materials is predictive of in-eye performance.