Hydrogel lens dehydration and subjective comfort and dryness ratings in symptomatic and asymptomatic contact lens wearers.

PURPOSE: To determine whether lens dehydration correlates with discomfort, dryness, and noninvasive tear break-up time in symptomatic and asymptomatic contact lens wearers and whether dehydration of the two lens types varies. METHOD: Twenty hydrogel contact lens wearers with dryness-related symptoms and 20 asymptomatic wearers wore an Etafilcon A lens (Acuvue; Vistakon, Inc., Jacksonville, Florida) in one eye and an Omafilcon A lens (Proclear; Biocompatibles, Norfolk, Virginia) in the contralateral eye for 7 h in a randomized, double-masked study. Lens water content was measured before and after 7 h of lens wear and prelens noninvasive tear film break-up time (NIBUT) was measured immediately after insertion and after 5 h of lens wear. Subjective comfort and dryness were rated at 0, 1, 3, 5, and 7 h of lens wear. RESULTS: The symptomatic group had significantly reduced prelens NIBUT, decreased comfort, and increased dryness, but there was no difference between lenses for these variables. The Omafilcon A lenses dehydrated significantly less than the Etafilcon A lenses, but there was no significant difference in lens dehydration between two subject groups. CONCLUSION: No correlation was found between lens dehydration and subjective dryness and comfort. Symptomatic hydrogel contact lens wearers with decreased wearing time had measurably decreased comfort, increased dryness ratings, and reduced NIBUT.     

Changes in ocular physiology, tear film characteristics, and symptomatology with 18 months silicone hydrogel contact lens wear.

PURPOSE: The purpose of this study was to evaluate the longitudinal changes in ocular physiology, tear film characteristics, and symptomatology experienced by neophyte silicone hydrogel (SiH) contact lens wearers in a daily-wear compared with a continuous-wear modality and with the different commercially available lenses over an 18-month period. METHODS: Forty-five neophyte subjects were enrolled in the study and randomly assigned to wear one of two SiH materials: lotrafilcon A or balafilcon A lenses on either a daily- (LDW; BDW) or continuous-wear (LCW; BCW) basis. Additionally, a group of noncontact lens-wearing subjects (control group) was also recruited and followed over the same study period. Objective and subjective grading of ocular physiology were carried out together with tear meniscus height (TMH) and noninvasive tear breakup time (NITBUT). Subjects also subjectively rated symptoms and judgments with lens wear. After initial screening, subsequent measurements were taken after 1, 3, 6, 12, and 18 months. RESULTS: Subjective and objective grading of ocular physiology revealed a small increase in bulbar, limbal, and palpebral hyperemia as well as corneal staining over time with both lens materials and regimes of wear (p < 0.05). No significant changes in NITBUT or TMH were found (p > 0.05). Subjective symptoms and judgment were not material- or modality-specific. CONCLUSIONS: Daily and continuous wear of SiH contact lenses induced small but statistically significant changes in ocular physiology and symptomatology. Clinical measures of tear film characteristics were unaffected by lens wear. Both materials and regimes of wear showed similar clinical performance. Long-term SiH contact lens wear is shown to be a successful option for patients.     

Postlens tear film morphology, lens movement and symptoms in hydrogel lens wearers

Postlens tear film morphology, lens movement and symptoms were assessed in 100 subjects wearing hydrogel contact lenses on a daily wear schedule. Postlens tear film appearance in specular reflection was categorized as amorphous, coloured, striated or dynamic (variable with bliniking), and subjects'symptoms were assessed using a questionnaire. Non-amorphous appearances were present in 25% of subjects and occurred approximateiy equally with HEMA, Acuvue. Igel 55 and other lens types. Patterned appearances were found to be associated with reduced lens movement (Kruskal-Wallis ANOVA, P < 0.001). The most common symptom (dryness) was not significantly related to postlens tear film appearance. Postlens tear film morphology was shown to be a determinant of lens movement, but may be unrelated to common symptoms.     

1-Day Acuvue vs. Focus Dailies: a comparison of comfort, user preference, and incidence of corneal complications.

PURPOSE: Two types of daily disposable soft contact lenses, 1-Day Acuvue (Johnson & Johnson K.K., Japan) and Focus Dailies (CIBA Vision Corp.), were compared for comfort, user preference, and any associated incidence of corneal complications. METHODS: 1-Day Acuvue and Focus Dailies were randomly prescribed for one eye each of 127 contact lens wearers. After 1 week of lens wear, user preference, anterior segment health, and tear film stability on the contact lenses were evaluated. RESULTS: Group A consisted of 45 subjects who had been wearing 1-Day Acuvue prior to the study and group B consisted of 82 subjects who had been wearing other types of soft contact lenses prior to the study. A statistically significant number of subjects in both group A and group B preferred 1-Day Acuvue. In group A there were significantly fewer corneal complications in the eyes with 1-Day Acuvue than in the eyes with Dailies. However, there was no difference in the incidence of corneal complications in group B. CONCLUSIONS: If Dailies are prescribed for current 1-Day Acuvue wearers, extra care may be required. 1-Day Acuvue lenses could be prescribed successfully for those who previously wore soft contact lenses other than 1-Day Acuvue.     

Effects of a 0.9% sodium chloride ophthalmic solution on the ocular surface of symptomatic contact lens wearers

BACKGROUND: Ocular surface-related discomfort is the main reason for stopping contact lens wear. We carried out a study to evaluate the efficacy of preservative-free artificial tears containing 0.9% sodium chloride on ocular surface signs and symptoms in contact lens wearers experiencing discomfort and its possible influence on the duration of contact lens wear. METHODS: We studied 49 contact lens wearers experiencing discomfort who had normal results of slit-lamp biomicroscopy, a fluorescein tear film break-up time (BUT) of 10 seconds or more, and wetting greater than 5 mm in 5 minutes on the Schirmer 1 test with and without anesthesia. Twenty-nine subjects (16 men and 13 women with a mean age of 32.5 years [standard deviation (SD) 8.7 years]) received one instillation of the 0.9% sodium chloride solution four times daily in the lower conjunctival fornix for 21 days. Twenty subjects (12 men and 8 women with a mean age of 35.1 [SD 6.2] years) received no drops and served as a control group. The overall comfort and duration of contact lens wear, results of tear film analysis and adverse events were recorded on days 7 and 21. Patients rated their symptoms (while not receiving any medications or hydrating solutions) on a 100-mm visual analogue scale with "Excellent (lenses not felt)" at the left and "Very uncomfortable (lenses cause irritation or discomfort)" at the right. Measurement of corrected visual acuity, slit-lamp examination, determination of the tear film BUT, the Schirmer 1 test with and without anesthesia, and assessment of the colour and surface of the lens were performed at baseline and at day 21. We analysed the data for the more uncomfortable eye or, if the eyes were equally uncomfortable, the right eye. RESULTS: Significant lessening of ocular discomfort was observed in the treatment group during the study: the mean rating on the visual analogue scale at baseline was 60.2 mm (SD 12.7 mm), compared with 35.8 mm (SD 18.0 mm) at day 21 (p < 0.001, Student's t test). The duration of contact lens wear was significantly longer at day 21 than at baseline (7.0 [SD 2.6] hours vs. 6.4 [SD 2.6] hours, p < 0.05, Student's t test), and the proportion of subjects with conjunctival hyperemia was significantly lower at day 21 (48.3% vs. 82.8%, p < 0.05, chi2 test). No statistically significant changes were observed in tear film BUT, results of the Schirmer 1 test, corneal punctate staining by fluorescein or results of tear film analysis. The treatment was well tolerated by all patients. No significant differences in any of the variables studied were observed in the control group. INTERPRETATION: Treatment with a preservative-free 0.9% sodium chloride ophthalmic solution reduced ocular surface discomfort and extended the duration of contact lens wear without interfering with the tear film or contact lens materials. Long-term studies are needed to confirm the role of this solution in reducing discomfort experienced by contact lens wearers.     

Evaluation of the safety and efficacy of therapeutic bandage contact lenses on post-cataract surgery patients

AIM: To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. METHODS: A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular surface disease index (OSDI) questionnaire, slit-lamp microscope examination of tear break-up time (TBUT), corneal fluorescein score (CFS), tear meniscus height (TMH) together with anterior segment optical coherence tomography (AS-OCT) and corneal topography were evaluated preoperatively and postoperatively. RESULTS: The subjective feeling (P=0.004), TBUT (P<0.001) and TMH (P=0.02) post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1wk post-surgery. Until three month postoperatively, the comfort degree (P=0.004) and TMH (P=0.01) of group two were still worse than group one. Moreover, TBUT (P<0.001) and CFS (P=0.004) of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. CONCLUSION: Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.     

【In Press】 Evaluation of the safety and efficacy of therapeutic bandage contact lenses on post-cataract surgery patients

AIM: To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. METHODS: A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular Surface Disease Index questionnaire (OSDI), slit-lamp microscope examination of tear break-up time (TBUT), corneal fluorescein score (CFS), tear meniscus height (TMH) together with anterior segment optical coherence tomography (AS-OCT) and corneal topography were evaluated preoperatively and postoperatively. RESULTS: The subjective feeling (P=0.004), TBUT (P<0.001) and TMH (P=0.02) post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1week post-surgery. Until three month postoperatively, the comfort degree (P=0.004) and TMH (P=0.01) of group two were still worse than group one. Moreover, TBUT (P<0.001) and CFS (P=0.004) of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. CONCLUSION: Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.     

Comparison of the impact of nesofilcon A hydrogel contact lens on the ocular surface and the comfort of presbyopic and non-presbyopic wearers

AIM: To assess and compare the impact of a daily disposable contact lens (CL) with high water content on the ocular surface and comfort of the presbyopic and non-presbyopic population after one day of use. METHODS: Totally 20 presbyopes and 30 non-presbyopes non-contact wearers were fitted with nesofilcon A CLs. CL thickness was measured to assess material stability during daily wear, and ocular surface parameters were also assessed. Optical quality was analyzed for all cases. In addition, CL comfort was rated. RESULTS: No significant differences were found in CL thickness, tear film osmolarity, average tear break-up time, bulbar redness, central corneal thickness, corneal volume, root-mean-square of higher-order aberrations (RMS of HOAs) and vertical and horizontal coma, either as a function of the group or time of use. A significant decrease in tear meniscus height and first break-up of the tear film was found in the presbyopic group (P=0.038; P=0.007 respectively). A decrease in spherical aberration coefficient was found after CL insertion (P=0.031 monofocal CL; P=0.023 low addition multifocal CL; P=0.016 high addition multifocal CL). Multifocal CL were thicker than monofocal CL (P=0.045). Comparison between groups showed more discomfort in presbyopes than non-presbyopes (P=0.003). CONCLUSION: This study evidence that the behavior of the daily disposable CL with high water content seems to be stable during the day of use. Ocular parameters measured during wear show that CL behavior is the same for presbyopes and non-presbyopes, being more uncomfortable for presbyopes.     

The effect of artificial tears on visual performance in normal subjects wearing contact lenses.

PURPOSE: Disruption of the anterior refracting surface of the eye reduces visual performance. In the case of a contact lens wearer, this surface is the prelens tear film. This study determined whether artificial tears stabilize the tear film in contact lens wearers and maintained optimal visual performance for a prolonged period. METHODS: Five normal subjects all in good general and ocular health and adapted to contact lens wear were fitted with Acuvue lenses. A temporal, two-alternative, forced-choice paradigm was used to measure contrast sensitivity. The stimuli were vertically oriented sine-wave gratings (between 0.5 and 14 cpd) presented for 16.67 ms. The stimuli were presented at two different times after blink detection: 2 s after blink detection (i.e., before tear layer break-up) or 4 s after tear film break-up. Three conditions were investigated at 4 s after tear layer break-up: (1) without artificial tears added, (2) with Clerz2 (Ciba Vision) instilled, and (3) with Sensitive Eyes (Bausch & Lomb) applied. The artificial tears were instilled at 10-min intervals during the experimental run. RESULTS: High spatial frequency contrast sensitivity was found to be reduced after tear film break-up and was not enhanced by either tear solution. CONCLUSIONS: This study indicates that there is no effect of Clerz2 or Sensitive Eyes in maintaining or improving visual performance beyond the normal prelens tear film break-up time in normal subjects wearing Acuvue lenses.     

A 1-year prospective clinical trial of balafilcon a (PureVision) silicone-hydrogel contact lenses used on a 30-day continuous wear schedule

PURPOSE: To evaluate silicone-hydrogel balafilcon A (PureVision, Bausch & Lomb Inc., Rochester, NY) contact lenses worn on a 30-day continuous wear basis when compared with a traditional hydrogel (Acuvue, Vistakon, Johnson and Johnson Vision Products, Inc., Jacksonville, FL) worn on a 7-day extended wear schedule. DESIGN: Prospective, comparative, paired-eye, interventional, multicenter clinical trial. PARTICIPANTS: Two hundred twelve ametropes with no significant ocular pathology. METHODS: Subjects with normal ocular health who conformed to a set of standard criteria were monitored at seven different sites around the globe. Subjects wore both study lenses simultaneously, one on each eye. Lenses were assigned to right and left eyes according to a randomized schedule. The silicone hydrogel was removed and replaced every month and the traditional hydrogel was removed every 7 days and replaced at 14-day intervals. Subjects were followed for up to 1 year with discontinuation on indication divided between lens-related causes, unrelated factors, and loss to follow-up. MAIN OUTCOME MEASURES: Discontinuations, symptoms, vision, lens fit, lens surface assessment, slit-lamp assessment, and patient preferences. RESULTS: One hundred twenty three subjects completed the 12-month wearing period. There were no vision-threatening events with either lens type. The silicone-hydrogel lenses showed statistically superior performance in physiologic terms with regard to epithelial microcysts, striae, corneal staining, limbal injection, and bulbar injection. Inflammatory reactions, such as corneal infiltrates and tarsal conjunctival abnormalities occurred at similar rates between the lens types. Visible deposition and postlens debris with associated transient corneal indentation were significantly lower with the traditional hydrogel material at specific time points in the study. Visual acuity was comparable with the two lens types. Subjects rated the silicone-hydrogel material as preferable on subjective scales of dryness, comfort, and lens handling. Overall subjective performance was rated superior with the silicone-hydrogel material. CONCLUSIONS: The high oxygen performance of the silicone-hydrogel lenses provides a superior physiologic environment compared with a traditional hydrogel material during continuous wear. Despite the slightly higher levels of visible deposit on the silicone-hydrogels, superior subjective responses suggest that the plasma coating technology on these lenses is effective in providing comfortable lens wear. The results look promising for the success of silicone-hydrogels as the material of choice for continuous wear contact lenses.     

Compatibility of two new silicone hydrogel contact lenses with three soft contact lens multipurpose solutions*.

Purpose: The purpose of this study is to assess corneal staining and subjective symptom ratings with six different silicone hydrogel contact lens/multipurpose solution combinations, including the recently launched Menicon PremiO silicone hydrogel contact lens, after the first night of soaking the lenses in solution. Methods: This study is a prospective, single-centre, subject-masked, contralateral, crossover, daily wear clinical trial in which subjects were randomly fitted in the morning with a different lens/solution combination in each eye, asked to wear the lenses for the whole day (at least 12 h), soak each of the lenses overnight in one of the test solutions and insert the lenses on the following morning. Subjects were asked to come on that morning for assessment of corneal staining and subjective ratings. All subjects repeated this procedure on another two occasions in order to collect the results of the six different lens/solution combinations: Menicon PremiO/MeniCare Soft; Menicon PremiO/Complete 10; Menicon PremiO/OptiFree Express; Acuvue Oasys/MeniCare Soft; Acuvue Oasys/Complete 10; Acuvue Oasys/OptiFree Express. Results: Menicon PremiO lenses were associated with a lower level of corneal staining overall, and in the nasal and temporal locations, compared with Acuvue Oasys lenses (p < 0.05). No significant differences were found in corneal staining between solutions (p > 0.05). An overall rate of solution-induced corneal staining per eye of 12% was found. Symptoms were very similar among the six different lens/solution combinations (p > 0.05). Discussion: The lower level of corneal staining found with Menicon PremiO lenses compared with Acuvue Oasys lenses might be attributed to material, surface and design differences between lens types. The overall rate of solution-induced corneal staining and symptomatology found between the different lens/solutions combinations is consistent with previous studies.     

Preliminary tear film measurements of tolerant and non-tolerant contact lens wearers

Background : The relationship between contact lens intolerance and tear stability, tear quantity, distribution and consistency has yet to be clearly established. In this study, we have examined the tear film of several tolerant and non-tolerant soft contact lens wearers. We aimed to develop a number of clinical and biochemical techniques to establish a correlation between one or more factors leading to contact lens intolerance. Methods : Subjects were separated by their self-described tolerance to contact lens wear. Five tolerant and five non-tolerant subjects were chosen. A McMonnies symptomatology questionnaire was used to ascertain subject history, while non-invasive tear break-up time (TBUT) examined tear stability. Basal tear collection was performed using glass capillary tubes, the tear flow rate was measured and one dimensional gel electrophoresis used to analyse protein differences. Results : Non-tolerant subjects experienced primary symptoms, such as dryness and grittiness, more often than tolerant subjects (p = 0.007). The TBUT of non-tolerant lens wearers was also reduced (average of seven seconds) compared to tolerant lens wearers (p < 0.002). Tolerant lens wearers had a longer more stable tear film with an average TBUT of 20 seconds and this correlated with a fast tear flow rate (p < 0.04). Protein gel electrophoresis showed that some subjects who were non-tolerant to lens wear had variations in their tear protein profiles compared to tolerant subjects. Conclusion : These preliminary results demonstrate that clinical and biochemical tear profiles can be used to differentiate subjects with good lens wear tolerance from those who may be non-tolerant to lens wear.     

The frequency of ocular symptoms during spectacle and daily soft and rigid contact lens wear.

PURPOSE: Ocular discomfort is the primary reason for discontinuation of contact lens wear. The purpose of the study was to quantify and compare the frequency of ocular symptoms experienced by spectacle wearers and wearers of soft and rigid daily contact lenses. METHODS: We analyzed the results of an ocular symptom survey of prospective volunteers for contact lens clinical trials during the period 1989 to 1995. Questions pertaining to lens-wear experience and ocular symptoms were answered by 883 untrained individuals without active ocular disease. The sample included 664 spectacle wearers, 171 soft contact lens (SCL) wearers, and 48 rigid gas-permeable (RGP) lens wearers. The frequencies of 10 ocular symptoms were compared for each group. Spearman's Rank Correlation was used to test for correlations between symptoms. The chi2 test was used to determine differences between subject groups, adjusted for multiple comparisons. RESULTS: There were no significant differences in the frequency of ocular symptoms between the soft contact lens (SCL) and RGP wearers. The most common symptom was ocular tiredness (27%). None of the symptoms were highly correlated, indicating that they are somewhat different "sensations." Despite ocular discomfort being the primary reason for discontinuation of lens wear, contact lens wearers experienced the same type and severity of symptoms as spectacle wearers. Thus (in order of frequency of occurrence), tiredness, itchiness, watering, pain, aching, excessive blinking, and burning had similar rates of occurrence for all three groups. The two major distinguishing symptoms were dryness and redness, which were reported far more frequently and with greater severity in both contact lens groups (p < 0.001). Grittiness was also reported more with RGP wearers than with spectacle wearers (p < 0.001). CONCLUSIONS: Contact lenses disturb the ocular environment, as evidenced by responses of increased ocular dryness, redness, and grittiness. Despite fundamental differences in SCL's and RGP contact lenses, both groups of contact lens wearers surveyed experienced a similar type and frequency of ocular symptoms.     

Corneal edema in divers wearing hard contact lenses

Polymethylmethacrylate (hard) contact lens-wearing Navy divers involved in hyperbaric research complained of ocular discomfort, halos, specular highlights, and decreased visual acuity during and immediately after the decompression phase of dry chamber dives. These symptoms were related to bubbles in the tear film between the cornea and hard contact lens. The bubbles developed during the decompression phase of the dive and represented the trapping (by the hard contact lens) of nitrogen outgassing from the cornea and precorneal tear film. The bubbles effected nummular patches of corneal epithelial edema persisting up to two hours after diving. Gas trapping and corneal edema were not observed in uncovered corneas or corneas covered with membrane lenses.     

Tear film,contact lenses and tear biomarkers

This article summarises research undertaken since 1993 in the Willcox laboratory at the University of New South Wales, Sydney on the tear film, its interactions with contact lenses, and the use of tears as a source of biomarkers for ocular and non‐ocular diseases. The proteome, lipidome and glycome of tears all contribute to important aspects of the tear film, including its structure, its ability to defend the ocular surface against microbes and to help heal ocular surface injuries. The tear film interacts with contact lenses in vivo and interactions between tears and lenses can affect the biocompatibility of lenses, and may be important in mediating discomfort responses during lens wear. Suggestions are made for follow‐up research.     

Defects in disposable contact lenses compromise ocular integrity

To ascertain the prevalence of defects in disposable contact lenses, an Optimec JFC contact lens analyser (× 16 magnification) was used to examine 150 Acuvue, 150 NewVues, and 150 SeeQuence lenses, all −3.00D in power. The percentage of each lens type found to be defective was: Acuvue 75%, NewVues 5%, and SeeQuence 9%. A single-center, simultaneously-controlled, double-masked, randomized study was conducted to determine whether such defects compromise ocular integrity. Each of 29 subjects wore a defective Acuvue lens in one eye and a non-defective Acuvue (control) lens in the other eye on an extended-wear basis for one week. Lenses with defects visible to the naked eye were excluded. Although there was no significant difference in vision, subjective sensation, or bulbar conjunctival hyperemia between eyes wearing defective vs. control lenses, a significantly greater ocular response was observed in eyes wearing defective lenses in the form of corneal epithelial microcysts (p = 0.04), corneal staining (p = 0.02), and conjunctival staining (p = 0.04). Two cases of peripheral corneal infiltrates were observed; both cases were unilateral and occurred in eyes wearing defective lenses. Such compromise may predispose the eye to more serious complications such as infection and corneal ulceration.     

The Max Schapero Memorial Award Lecture 2004: contact lenses on and in the cornea, what the eye needs.

PURPOSE: The aim of this study is to review the advances made in understanding the needs of the cornea and the way in which it responds to contact lens wear and corneal implants. METHODS: The review is based on personal knowledge and involvement of the author and colleagues from the 1970s to 2005. RESULTS: Development of silicone hydrogel contact lenses is presented as well as development of synthetic materials for implantation on the corneal surface (corneal onlay). CONCLUSIONS: The future of vision correction involves developing highly porous and biocompatible lens materials. For contact lenses, a better understanding of the effects of contact lens wear on the ocular surfaces, including the tear film, and development of lens materials with greater bacterial resistance are required. For those who require new solutions to permanent vision correction, corneal onlays (implantable contact lenses) are a minimally invasive and totally reversible procedure that can be removed or replaced as visual needs change over time.     

Disposable contact lenses vs. contact lens maintenance for extended wear

We compared a disposable extended wear contact lens modality with conventional extended wear over a 6-week period. To do so, we refit 31 patients who had successfully worn conventional extended wear contact lenses for more than 1 year. One eye was fit with the AcuvueR disposable contact lens, and a new extended wear lens of the type the patient had been wearing was placed on the other eye. At weekly intervals the disposable lens was discarded and a new disposable lens inserted. At the same time, the conventional lens on the fellow eye was cleaned, disinfected, and reinserted. After 6 weeks the ocular response, subjective impressions, and condition of the lenses in the two eyes were compared. Both lenses were then cultured. Three subjects had to discontinue disposable lens wear because of adverse reactions to trapped cellular debris and corneal microcysts. Although the results were not statistically significant, the Acuvue lens appeared to perform better than or equal to the conventional lens in biomicroscopic observation, visual acuity measurement, and subjective patient preference. Eighty-seven percent of patients preferred to continue with the disposable system. There were no differences found in the type or degree of microbial contamination of the lenses.     

Use of a high molecular weight fluorescein (fluorexon) ophthalmic strip in assessments of tear film break-up time in contact lens wearers and non-contact lens wearers

Purpose: To assess whether fluorexon strips could be used in tear stability [tear film break‐up time (TBUT)] measures, as compared with fluorescein strips. Methods: The pre‐ocular tear film stability was assessed in 40 adults (19–29 years of age), half of whom were adapted soft contact lens wearers, using the dye‐assisted tear film break‐up time (TBUT) method. The measures were carried out between 10.00 and 17.00 hours, with contact lens wearers removing their lenses just before the assessments. For all subjects, fluorescein or fluorexon ophthalmic strips (pre‐wetted with preservative‐free saline) were used to add dye to the tear film, the TBUT was assessed three times and then the eye lightly irrigated with saline. The measures were repeated 45 min later with the other dye, with half the subjects receiving fluorescein first and the other half receiving fluorexon first. Results: Overall, the mean TBUT times were 12.2 ± 5.9 s for fluorescein and 12.6 ± 5.6 s for fluorexon (p = n.s.), but the non‐lens wearers had longer TBUT times (14.6 and 14.5 s for the two dyes) compared with contact lens wearers (9.8 and 10.7 s, p < 0.01). While the inter‐subject variability (as S.D.) was larger for non‐contact lens wearers, the intra‐subject variability [as coefficient of variation (COV)] was greater in the contact lens wearers when fluorescein was used (p < 0.001). When analysed as a function of the time of day that the measures were made, there were clear trends for both the fluorescein and fluorexon. TBUT values to increase in non‐contact lens wearers and decrease in contact lens wearers. These trends failed to reach statistical significance, but the results with the contact lens wearers showed less variation than the non‐contact lens wearers. Conclusion: The use of a fluorexon dye‐impregnated strip (pre‐wetted with preservative‐free saline) yielded comparable results with a fluorescein strip for assessments of tear film stability based on TBUT. The studies also indicate that further research is needed on changes in TBUT values during the day.     

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.