Pre-contact lens and pre-corneal tear film kinetics.

PURPOSE: Contact lenses (CL) insulate the corneal surface from the environment. It is possible that they influence the corneal sensory mechanism that contribute to spontaneous blinking. The study objective was to quantify the pre-CL and pre-corneal tear film kinetics (TFK) over blink period. METHODS: The study population was 202 soft CL wearers, 133 non-lens wearers. TFK were quantified via post-hoc masked analysis of HD Tearscope videos. The parameters were: Non-Invasive Break Up Time (NIBUT), Exposed Area % at initial break (EA 1st Break) and at blink (EA Blink), Interblink period (IB), Protective Index (PI) and exposure speed of surface dehydration (ES mm2/s). The TFK of CL wearers were compared to non-lens wearers. The hypothesis was that pre-CL TFK was inferior to pre-corneal, specifically greater tear film anomalies presence at blink. RESULTS: The pre-corneal NIBUT was longer than pre-CL NIBUT (9.1 vs. 5.1s, p < 0.001). The EA 1st Break was smaller for pre-corneal than pre-CL (0.003 vs. 0.43%, p < 0.001). The mean IB time was similar for pre-CL and pre-corneal (9.4 vs. 9.8s, p = 0.213). The EA Blink % was smaller for pre-corneal than pre-CL (0.03 vs. 6.66%, p < 0.001). The ES was faster for pre-CL than pre-corneal (0.339 vs. 0.004, p < 0.001). The PI was greater for pre-corneal than pre-CL (99.9 vs. 97.1%, p < 0.001). CONCLUSIONS: Pre-CL TFK were significantly inferior than pre-corneal, confirmed the hypothesis. The NIBUT was shorter. Once the initial break occurred, ES was faster, and EA was much greater for pre-CL than pre-corneal. The differences identified may be an aetiological component of CL discomfort and the relationship between TFK and discomfort in contact lens wearers should be investigated.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

The Effects of Age, Refractive Status, and Luminance on Pupil Size.

PURPOSE: Pupil size is critical for optimal performance of presbyopic contact lenses. Although the effect of luminance is well known, little information is available regarding other contributing factors such as aging and refractive status. METHODS: The cohort population comprised 304 patients (127 male, 177 female) aged 18 to 78 years. Pupils were photographed at three controlled luminance levels 250, 50, and 2.5 cd/m using an infra-red macro video camera. Measurements of pupil diameter were conducted after transforming pixel values to linear values in millimeters. RESULTS: Luminance was the most influential factor with pupil diameter increasing with decreased luminance (p < 0.001, all comparisons). Age was also found to be a significant factor with a smaller diameter in the older groups, but overall the difference was only significant between the pre-presbyopes and the established presbyopes (p = 0.017). Pupil diameter decreased significantly with increasing age, the effect being most marked at low luminance (<0.001). The smallest pupil diameters were measured for hyperopes and the largest for myopes and although refractive error was not a significant factor alone, there was a significant interaction between luminance and refractive error with the greatest differences in pupil diameter between myopes and emmetropes at low luminance (p < 0.001). Pupil diameter changes modeled by multilinear regression (p < 0.001) identified age, luminance, best sphere refraction, and refractive error as significant factors accounting for just over 70% of the average variation in pupil diameter. CONCLUSIONS: Both age and refractive status were found to affect pupil size with larger pupils measured for younger patients and myopes. Designs for multifocal contact lens corrections should take both age and refractive status into consideration; a faster progression from distance to near corrections across the optical zone of the lens is expected to be required for established presbyopes and hyperopes than it is for early presbyopes, myopes, and emmetropes.

Association Between Contact Lens Discomfort and Pre-lens Tear Film Kinetics.

PURPOSE: The relationship between contact lens wettability and comfort has been extensively evaluated; however, a direct correlation between the characteristics of the pre-lens tear film and the symptoms associated with contact lens discomfort has yet to be established. In addition, there is relatively limited knowledge relating to the entire tear film kinetics during the inter-blink period in contact lens wearers. The purpose of this analysis was to identify the characteristics of the pre-lens tear film kinetics that may be associated with the symptoms of contact lens discomfort. METHODS: The study population comprised 202 soft (hydrogel and silicone hydrogel) contact lens wearers attending pre-screening visits at the OTG-i research clinic. All participants completed the Ocular Surface Disease Index (OSDI) questionnaire and the tear film was quantified via post hoc, masked analysis of high definition digital Tearscope videos recorded at the visit. The tear film kinetics of the least symptomatic wearers (OSDI lowest quintile scores, n = 45) were compared to the tear film kinetics of the most symptomatic wearers (OSDI highest quintile scores, n = 43). The hypothesis tested was that the tear film kinetics of asymptomatic wearers were better than tear film kinetics of symptomatic wearers. RESULTS: The distribution of lens types worn was as follows: Daily Disposable 46.5%, 1-Month Replacement 39.6%, and 2-Week Replacement 13.6%. 48.2% of lenses were silicone hydrogel and 51.8% hydrogel. Symptomatic wearers had a shorter break-up time (4.7 s vs. 6.0 s; p = 0.003), lesser surface coverage by the tear film during the interblink period (95.1% vs. 98.5%; p < 0.001) and greater surface exposure at the time of the blink (9.4% vs. 3.9%; p = 0.001). CONCLUSIONS: The current study demonstrated that the tear film kinetics of asymptomatic and symptomatic contact lens wearers were different, the findings supporting the hypothesis of poorer tear film kinetics for symptomatic than asymptomatic wearers in a general contact lens wearing population.

A multi-country assessment of compliance with daily disposable contact lens wear.

PURPOSE: To investigate compliance with daily disposable contact lens (DDCL) wear and investigate re-use of lenses according to country and DDCL material worn. METHODS: Optometrists invited eligible DDCL patients from their practices to participate in a survey on DDCL wear in Australia, Norway, the United Kingdom (UK) and the United States (US). Eligible participants completed an online or paper version of the survey. RESULTS: 805 participants completed the survey (96% online): Australia 13%, Norway 32%, UK 17%, US 38%. The median age was 38 years; 66% were female. Silicone hydrogel (SiHy) DDCLs were worn by 14%. Overall, 9% were non-compliant with DDCL replacement; Australia 18%, US 12%, UK 7% and Norway 4%. There were no differences with respect to sex, years of contact lens wear experience or DDCL material (SiHy versus hydrogels). The primary reason for re-use was "to save money" (60%). Re-use of DDCLs resulted in inferior comfort at insertion and prior to lens removal (p=0.001). 75% reported occasional napping and 28% reported sleeping overnight for at least one night in the preceding month, while wearing their DDCLs. CONCLUSION: Non-compliance with replacement of DDCLs occurred in all countries investigated; the rate was highest in Australia and lowest in Norway. Re-use of DDCLs was associated with reduced comfort. DDCL wearers often reported wearing lenses overnight. It is important for optometrists to counsel their patients on the importance of appropriate lens wear and replacement for DDCLs.

Exploring compliance: a mixed-methods study of contact lens wearer perspectives.

PURPOSE: Using both quantitative and qualitative research methods, this article explores in detail the lens wear and care habits of adapted contact lens wearers and seeks a better understanding of what enables and constrains patient compliance with appropriate lens wear and lens care. METHODS: The study was conducted in two phases: a preliminary online questionnaire (quantitative phase), identifying types of noncompliance, and a series of sequentially conducted focus groups (qualitative phase), exploring constraints to, and enablers of, compliance. RESULTS: One hundred participants completed the online questionnaire; 12 of them also participated in one of four focus groups. The most frequently reported aspects of noncompliance revealed were failure to replace lenses when scheduled, inappropriate lens purchase and supply, sleeping while wearing lenses, use of tap water with lenses and failure to wash hands, failure to clean and replace cases regularly, and inappropriate use of care systems. Using an iterative process, a number of "themes" associated with noncompliance were identified in the focus group discussions. The most frequently occurring themes related to the consequences that may occur if patients were noncompliant with one or more aspects of their contact lens wear and the importance of receiving instructions regarding the most appropriate way to wear and care for their lenses. Most of the themes that emerged during the analysis were both constraints to, and enablers of, compliance. CONCLUSIONS: This study confirms the frequent types of noncompliance with contact lens wear and care while offering a greater understanding of what may constrain and enables contact lens wear and care compliance. Future qualitative studies may help eye care practitioners and the contact lens industry to develop strategies and tools to aid compliance and success in contact lens wear.

Soft contact lens-related dryness with and without clinical signs.

PURPOSE: To report demographics, wearing patterns, and symptoms from soft contact lens (SCL) wearers with significant SCL-related dryness symptoms with and without significant ocular signs of dryness. METHODS: In a multicenter, prospective observational clinical trial, symptomatic SCL wearers reported significant SCL-related dryness via self-administered questionnaire of frequency and intensity of dryness after a dry eye (DE) examination. DE etiology was assigned post hoc by an expert panel, and those with and without significant DE-related signs were analyzed by univariate logistic regression. Possible DE etiologies were aqueous tear deficiency, SCL-induced tear instability, meibomian gland dysfunction, or "other." Wearers without signs that qualified for any DE etiology were designated as No DE Signs (NDES). RESULTS: Of the 226 SCL symptomatic wearers examined, 23% were without signs, 30% had aqueous tear deficiency, 25% had SCL-induced tear instability, 14% had meibomian gland dysfunction, and 8% had "other" diagnoses. The NDES wearers had significantly longer pre-lens break-up time (9.8 vs. 6.6 s, p < 0.0001), better lens wetting (3.4 vs. 2.4 0 to 4 scale, p < 0.0001), lower levels of film deposits on lenses (0.45 vs. 0.92, 0 to 4 scale, p < 0.0001), and of most slit lamp signs. The NDES wearers were significantly more likely to be male (36% vs.19%, p = 0.013), were less likely to have deteriorating comfort during the day (81% vs. 97%, p = 0.001), reported longer average hours of comfortable wear (11 ± 3 vs. 9 ± 4 h, p = 0.014), had older contact lenses (18 ± 14 vs. 13 ± 12 days, p = 0.029), and greater intensity of photophobia early and late in the day (p = 0.043 and 0.021). CONCLUSIONS: Symptoms of dryness in SCL wearers stem from a variety of underlying causes. However, nearly one-quarter of these symptomatic SCL wearers appear to be free of signs of dryness. The effective management of CL-related dryness requires a comprehensive range of clinical assessments and the use of a diverse range of management strategies.

Ability of patients to recall habitual contact lens products and enhancement of recall using photographic aids.

PURPOSE: To determine the proportion of soft contact lens (CL) wearers who are able to recall their habitual products (lenses and care system) correctly from memory, and to evaluate the value of using photographic aids (PAs) to improve recall. METHODS: 103 soft lens wearers attended 2 visits to investigate their habitual CL product use. At the first visit they were asked to recall which products they were using and then to identify their products from PAs. They returned for a second visit with their products for confirmation. RESULTS: 51% correctly reported their lens brands from memory alone, which improved to 87% with the use of the PAs (p<0.001). 41% correctly reported their habitual care system from memory alone, which improved to 80% with the use of PAs (p<0.001). Females were better at recalling care system brand names than males (49% versus 27% correct, p=0.040) and wearers with more than 1 year experience with their habitual CLs had better recall than those with up to 1 year experience (63% versus 27%, p=0.014). CONCLUSION: Less than 50% of contact lens wearers were able to recall the names of their habitual lens and lens care products correctly from memory. PAs improved this recall significantly for both contact lenses and contact lens care systems.

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.

Patient use of smartphones to communicate subjective data in clinical trials.

PURPOSE: Various methods have been used in clinical trials to collect time-sensitive subjective responses, including study diaries, telephone interviews, and use of text messaging. However, all of these methods are limited by the uncertainty of when the participants enrolled in the study actually record their responses. This technical note reports on the utility of the BlackBerry smartphone to collect such data and why such a system provides advantages over other methods to report subjective ratings in clinical studies. METHODS: The Centre for Contact Lens Research developed an on-line web-enabled system that permits participants to record and immediately transmit subjective rating scores in numerical form directly into a web-enabled database. This, combined with the utility of BlackBerrys, enabled time-specific e-mail requests to be sent to the study participants and then for that data to be simultaneously transmitted to the web-enabled database. This system has been used in several clinical trials conducted at the Centre for Contact Lens Research, in which data were collected at various times and in several specific locations or environments. RESULTS: In the clinical trials conducted using this system, participants provided responses on 97.5% of occasions to the requests for data generated by the automated system. When the request was for data on a set date, this method resulted in responses of 84.1% of the time. CONCLUSIONS: The series of clinical trials reported here show the benefits of the utilization of the BlackBerry to collect time- or environment-sensitive data via a web-enabled system.

Comfort and vision with silicone hydrogel lenses: effect of compliance.

PURPOSE: Silicone hydrogel (SH) lenses are usually replaced after 2 weeks (2W) or 1 month (1M); however, many patients do not comply with the manufacturers' recommended replacement frequency (MRRF). The purpose of this analysis was to investigate the effect of compliance with MRRF on comfort and vision in SH wearers. METHODS: As a part of a larger study investigating compliance with MRRF, patients were asked to rate their subjective comfort and vision from 0 (very poor) to 10 (excellent) in the morning, at the end of the day (EVE), when lenses were new, and needed replacing (NR). RESULTS: One thousand three hundred forty-four patients wore 2W replacement modality (2WR) (n = 717) or 1M replacement modality (1MR) (n = 617) SH lenses. Comfort and vision in the morning and when lenses are new were significantly higher than for EVE and NR (p < 0.001). Twenty-nine percent (95% confidence interval 25.3-32.4) of 1MR and 59% (95% confidence interval 55.5-62.7) of 2WR wearers were non-compliant with the MRRF. Compliance had a significant effect on EVE (p = 0.002, p = 0.008) and NR (p < 0.001, p < 0.001) comfort and vision. After accounting for compliance, EVE and NR comfort and EVE vision were higher for 1MR than 2WR (p = 0.015, p = 0.044, p = 0.019). CONCLUSIONS: Compliant patients had better EVE and NR comfort and vision than non-compliant patients, regardless of replacement modality. Optimal subjective performance with SH lenses seems to be facilitated by replacing lenses as recommended.

Clinical performance of different care systems with silicone hydrogel contact lenses.

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 +/- 1.47 h; 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.

Compliance with contact lens replacement in Canada and the United States.

PURPOSE: To assess eye care practitioners (ECPs) recommendations for replacement frequency (RF) of silicone hydrogel (SH) and daily disposable (DD) lenses in Canada and the U.S. and to compare noncompliance (NC) with manufacturer recommended RF by the ECP and patient, and the reasons given for NC. METHODS: Invitations to participate were sent by e-mail to ECPs in Canada and the U.S. Twenty patient surveys were sent to 420 ECPs, and 2232 eligible surveys were received from 216 ECPs (26% Canada, 74% U.S.). Questions related to patient demographics, lens type, wearing patterns, ECP instructions for RF, and actual patient RF. ECPs provided lens information and their recommendation for RF after the surveys were completed and sealed in envelopes. Responses were anonymous. RESULTS: DD accounted for 18% (Canada) vs. 16% (U.S.) of wearers (p > 0.05); 35% (Canada) vs. 45% (U.S.) wore 2-week replacement SH (2WR; p = 0.011); and 47% (Canada) vs. 39% (U.S.) wore 1-month replacement SH (1MR) lenses (p = 0.025). Thirty-four percent (Canada) vs. 18% (U.S.) of ECPs recommended longer RFs than the manufacturer recommended RF for 2WR lens wearers (p < 0.001); 6% (Canada) vs. 4% (U.S.) for DD wearers; and 2% (Canada) vs. 1% (U.S.) for 1MR lens wearers. NC rates for actual RFs reported by patients were not different between countries (p > 0.05) and were lowest for DD (13% Canada, 12% U.S.), followed by 1MR (33% Canada, 28% U.S.). The highest NC rates were with 2WR (50% Canada, 52% U.S.). The most frequent reason for NC with 2WR and 1MR was "forgetting which day to replace lenses" (54% Canada, 53% U.S.) and in DD wearers "to save money" (56% Canada, 29% U.S., p < 0.001). CONCLUSIONS: 1MR lenses are more frequently prescribed in Canada. ECPs in Canada were NC with 2WR lenses more frequently than U.S. ECPs, but patient NC rates were the same in both countries for all lens types. ECP and patient NC rates were highest for 2WR lens wearers.

Comfort and adaptation to silicone hydrogel lenses for daily wear.

OBJECTIVES: To investigate initial comfort and adaptation of currently successful low oxygen transmissibility soft lens wearers refitted with silicone hydrogel (SH) lenses for daily wear. METHODS: Fifty-five subjects were enrolled in a subject-masked 5-month clinical trial in which they wore 5 SH lenses in a randomized, crossover design. Comfort, burning, and dryness were rated on scales of 0 to 100 immediately on insertion and the time for lens settling was recorded. Symptoms were then rated at various times, using BlackBerry wireless communication devices (Research in Motion, Waterloo, Canada), during the day for 2 cycles of 2 weeks wear for each lens type. RESULTS: Comfort immediately on insertion varied between lens types (P=0.002). All lens types were reported by the subjects to have settled within 30 to 45 sec of insertion (P=0.14) and "settled" comfort was greater than comfort immediately on insertion (P<0.001). Comfort within the first hour of wear also varied between lens types (P=0.02). Comfort during the day decreased significantly for all lenses (P=0.001), but there was no difference between lenses (P=0.19) and no effect of lens age (P=0.15). The wearing times were greater with the SH lenses than the habitual lenses worn before study commencement (P=0.001). Overall performance of the lenses after 4 weeks was high, with no difference between lenses (P=0.45). CONCLUSIONS: Initial comfort and adaptation to all SH lenses were good and no differences in the overall ratings were found between the 5 SH lenses investigated. Decreased comfort was noted later in the day with all lens types, but longer wearing times were reported with the SH lenses than previous hydroxyethyl methacrylate-based lenses.

Objective and subjective responses in patients refitted to daily-wear silicone hydrogel contact lenses.

PURPOSE: Silicone hydrogel (SiH) lenses offer many physiological advantages for daily wear (DW) in addition to the continuous-wear modality for which they were originally developed. The purpose of this study was to investigate the clinical performance and physiological responses in a group of successful long-term wearers of conventional hydrogel lenses when refitted with DW SiH contact lenses. METHODS: Eighty-seven successful soft lens wearers (8.4+/-4.7 years of prior lens wear) participated in this study. Bulbar and limbal hyperemia were subjectively graded and digitally photographed for subsequent masked objective evaluation. Subjective symptoms were scored using visual analog scales. In addition, refractive error, corneal curvature, and corneal thickness were measured. All subjects were refitted with Focus Night & Day (lotrafilcon A) SiH lenses; however, to reduce the potential for bias, they were informed that they were being randomly assigned to wear either low oxygen permeability (Dk) lenses or high Dk SiH lenses and were "masked" as to their lens assignment. Subjects returned after 1 week, 1 month, and 2 months of DW, at which time all gradings, photographs, and measurements were repeated. End-of-day subjective symptoms were also graded periodically during the study. RESULTS: Ninety-three percent of subjects were successfully refitted. Both objective and subjective evaluations showed that bulbar and limbal hyperemia decreased significantly in all quadrants during the study (p<0.001), particularly for those subjects with greater baseline hyperemia (p<0.001). Subjects reported a concurrent reduction in end-of-day dryness and improved end-of-day comfort compared with their habitual lenses (p<0.001). No significant changes in refractive error, tarsal papillary response, corneal curvature, or corneal thickness were found during the study. CONCLUSIONS: Hyperemia in contact lens wearers may be attributed to a number of factors, including hypoxia. Refitting existing low Dk lens wearers with SiH lenses on a DW basis can result in a decrease in hyperemia, which may be significant for some subjects and also results in improvements in symptoms of dryness and discomfort.

Dryness and discomfort with silicone hydrogel contact lenses.

PURPOSE: The purpose of this study was to determine whether symptoms of dryness and discomfort are experienced differently with silicone hydrogel lenses compared to conventional hydrogels, in symptomatic and asymptomatic subjects. METHODS: Thirty-nine symptomatic and asymptomatic subjects wore four types of lenses: Focus NIGHT & DAY (CIBA Vision), Focus DAILIES (CIBA Vision), ACUVUE 2 (Johnson & Johnson Visioncare) and Proclear Compatibles (CooperVision) contralaterally for 7 hours and rated comfort and dryness on a zero-to-100 point visual analog scale at 0, 1, 3, 5 and 7 hours. RESULTS: In both groups, no lens differences were found for comfort and dryness, but the comfort and dryness ratings of the symptomatic group decreased significantly (became worse) over the 7-hour period. CONCLUSIONS: These results demonstrate that dryness and comfort is the same over time with silicone hydrogel as with the other three lenses.

Effect of lens base curve on subjective comfort and assessment of fit with silicone hydrogel continuous wear contact lenses.

PURPOSE: To study the effect of base curve on subjective comfort of silicone hydrogel extended wear lenses. METHODS: Ninety-five subjects were first trial fitted with 8.6-mm base curve lotrafilcon A (Focus Night & Day) lenses and then with 8.4-mm lenses only if poor subjective comfort or poor fit was present. Comfort and fit were assessed after 15 min. Subjects with discomfort or signs of poor fit were then trial fitted with 8.4-mm lenses. RESULTS: Of 190 eyes, 74.2% were fitted with 8.6-mm lenses, and 23.7% required 8.4-mm lenses. Two (2.1 %) subjects could not be fitted with either base curve. Mean steep keratometry (K) reading for eyes dispensed with 8.6-mm lenses was 43.88 D and 45.56 D for eyes dispensed in the 8.4-mm lenses (p < 0.001). CONCLUSIONS: A clinically useful criterion showing the need for 8.4-mm lenses was steep K of > or = 45.50 D; 77% of these eyes required the steeper lens for good comfort and fit. Subjective discomfort with 8.6-mm lenses was also a useful signal for the need of a steeper lens; mean comfort scores for those subjects rose from 6.33 with 8.6-mm lenses to 9.44 with the 8.4-mm lenses for eyes requiring the steeper lens (p < 0.001).