Use of ClearGuard HD caps in pediatric hemodialysis patients.

BACKGROUND: Bloodstream infections (BSIs) are a leading cause of hospitalizations and mortality among patients receiving hemodialysis (HD) therapy, especially those with a central venous catheter (CVC) for dialysis access. The use of chlorhexidine impregnated catheter caps (ClearGuard) has been associated with a decrease in the rate of HD catheter-related BSIs (CA-BSIs) in adults; similar data have not been published for children. METHODS: We compared CA-BSI data from participating centers within the Standardizing Care to Improve Outcomes in Pediatric Endstage Kidney Disease (SCOPE) collaborative based on the center's use of ClearGuard caps for patients with HD catheter access. Centers were characterized as ClearGuard (CG) or non-ClearGuard (NCG) centers, with CA-BSI data pre- and post-CG implementation reviewed. All positive blood cultures in participating centers were reported to the SCOPE collaborative and adjudicated by an infectious disease physician. RESULTS: Data were available from 1786 SCOPE enrollment forms completed January 2016-January 2022. January 2020 served as the implementation date for analyzing CG versus NCG center data, with this being the time when the last CG center underwent implementation. Post January 2020, there was a greater decrease in the rate of HD CA-BSI in CG centers versus NCG centers, with a decrease from 1.18 to 0.23 and 0.41 episodes per 100 patient months for the CG and NCG centers, respectively (p = 0.002). CONCLUSIONS: Routine use of ClearGuard caps in pediatric dialysis centers was associated with a reduction of HD CA-BSI rates in pediatric HD patients.

Lens and solution properties in patients with and without midday fogging.

INTRODUCTION: Midday fogging is a complication of scleral lens (SL) wear that interrupts clear vision during the course of wear. SLs can be made with a variety of gas permeable materials, sizes and surface treatments, and various solutions are available for storing the lenses and for filling them before application on the eye. Many of these factors have been implicated as possible contributors to midday fogging. This study explored the lens and solution properties in habitual SL wearers with and without midday fogging. METHODS: In this prospective study, 48 habitual SL wearers were evaluated and asked to report whether they experienced midday fogging and if they removed their lenses during the day. They completed the Ocular Surface Disease Index (OSDI), which is a validated tool for dry eye assessment. Lens parameters (material, coatings and diameter) and lens storage and filling solutions were documented. Backward elimination of regression terms evaluated the lens and solution properties in those with and without fogging. OSDI scores were compared using the Mann-Whitney analysis. RESULTS: Collectively, the lens properties and solutions accounted for 27.7% of the variance related to midday fogging. None of the factors alone had a significant impact upon midday fogging. The median (interquartile range) OSDI score for those with fogging [37 (35)] was significantly different from those without fogging [10 (15)], with the scores corresponding to severe dry eye and normal eyes, respectively. CONCLUSION: SL wearers with midday fogging exhibited similar symptoms to patients with severe dry eye. Lens and solution characteristics may play a small role in patients with midday fogging, although changing just a single factor is not likely to impact its presence.

Patient Experiences With Therapeutic Contact Lenses and Dry Eye Disease.

OBJECTIVES: To report patient-reported experiences with dry eye disease and therapeutic contact lenses. METHODS: A survey was distributed to patients with dry eye disease. Demographics, Ocular Surface Disease Index (OSDI), systemic disease, contact lens history, and burden of care information were collected. Descriptive statistics are presented and categorized by nonlens, soft lens, and scleral lens (SL) wearers. RESULTS: Of 639 respondents, 15% (94/639) were currently using therapeutic soft or SLs (47 soft and 69 SL). Mid-day fogging or clouding of vision was reported by SL (75%, 50/67) and soft lens (62%, 29/47) wearers. Seventy-two percent of SL wearers spent more than 20 min daily on dry eye treatment while 43% of soft lens wearers spent more than 20 min. Median annual expenditure was higher for SL ($1,500, n=63) than nonlens ($500, n=371) or soft lens wearers ($700, n=43). Mean OSDI scores in all groups were in the severe category (51±22 years, n=401 nonlens wearers; mean age; 45±22 years, n=47 soft lens wearers; 60±24 years, n=69 SL wearers). CONCLUSIONS: Mid-day fogging and blurring of vision was reported by most of the individuals using therapeutic lenses for dry eye disease. SL wearers allocate the most resources for dry eye care.

Patient-Reported Dry Eye Treatment and Burden of Care.

OBJECTIVES: Dry eye is a common condition that can decrease the quality of life. This survey-based study of persons with dry eye investigated self-reported treatments (initial, current), out-of-pocket expenses, time spent on self-management, sources of care, and sources of information about their condition. METHODS: Online dry eye newsletters and support groups were emailed a link to an electronic survey asking members to participate. Survey respondents were not required to answer every question. RESULTS: In total, 639 persons with self-reported dry eye responded (86% women, 14% men [n=623]; mean ± SD age, 55 ± 14 years [n=595]). Artificial tears were the most reported intervention (76% initially, 71% currently). The median (interquartile range) out-of-pocket treatment cost annually was $500 ($200-$1,320 [n=506]). In addition, 55% (n=544) estimated 5 to 20 min daily on self-management; 22% spent an hour or more. Ophthalmologists provided most dry eye care (67%, n=520). Only 48% (n=524) reported that their primary source of dry eye information came from their eye care clinician. CONCLUSIONS: Artificial tears are the primary treatment for dry eye. Ophthalmologists provide most dry eye care, but half of patients report that their eye care provider is not their primary source of information. Almost one fourth of patients spend an hour or more daily on treatments.

Process and Outcomes of Fitting Corneoscleral Profilometry-Driven Scleral Lenses for Patients With Ocular Surface Disease.

OBJECTIVES: To assess the feasibility of obtaining cornea scleral profile (CSP) measurements using Scheimpflug imaging and report on the fitting process of free-form custom scleral lenses (SLs) for patients with ocular surface disease (OSD). METHODS: This prospective study of patients fit with free-form SLs collected data on the following: demographics, indications for wear, corneal and scleral tomography, scan acquisition process, and SL fitting process. RESULTS: Cornea scleral profile scans were acquired on 15 eyes of nine patients. Mean scan time for right eyes was 10.7, and 9.7 min for left eyes. A mean of 2.9 follow-up visits were required to complete SL fitting, with a mean of 2.1 lenses ordered. One eye did not tolerate lens wear, and one eye could not be fit using the CSP scan because of insufficient data. The initial lens ordered was dispensed at the first follow-up visit for seven of the remaining 13 eyes, all of which were ultimately fit successfully in free-form lenses. CONCLUSIONS: In this study of profilometry-guided SL fitting for eyes with OSD and low magnitude corneal astigmatism, the number of lenses and follow-up visits required were similar to outcomes of previous studies that described the diagnostic approach to SL fitting. In addition, imaging technology does not negate the need for skilled clinical observation while fitting SLs.

Prescription Habits of Scleral Lenses for the Management of Corneal Irregularity and Ocular Surface Disease Among Scleral Lens Practitioners.

OBJECTIVES: To describe prescribing patterns of therapeutic scleral lenses (SLs) in the management of corneal irregularity and ocular surface disease among practitioners who prescribe SLs. METHODS: Participants ranked treatment options for corneal irregularity and ocular surface disease in the order they would generally consider using them in an electronic survey. Median rank score for each option is reported, along with the percentage of participants assigning first place ranking to each option. The percentage of participants assigning first, second, or third place ranking to each option is also reported. RESULTS: Seven hundred and seventy-eight practitioners participated. Scleral lenses are most frequently considered as the first choice for the management of corneal irregularity based on overall median rank, followed by corneal rigid lenses (rigid gas-permeable [RGPs]). Scleral lenses were the first choice of 42% of participants, followed by RGPs (20%). For ocular surface disease, lubricant drops are most frequently used first, followed by meibomian gland expression, topical cyclosporine or lifitegrast, topical steroids, punctal plugs, and SLs, respectively. Lubricant drops were the first therapeutic option considered for ocular surface disease by 63% of participants and 45% ranked SLs as their sixth, seventh or eighth treatment based on median overall rank. CONCLUSIONS: Scleral lenses were identified as the first option for management of corneal irregularity more frequently than RGPs. Scleral lenses are considered for management of ocular surface disease before surgical intervention but after meibomian gland expression, punctal occlusion, and topical medical therapy are attempted.

Survey-Based Estimation of Corneal Complications Associated with Scleral Lens Wear.

ABSTRACT: The benefits of scleral lens (SL) wear have been described in cross-sectional and retrospective studies; however, the frequency of complications associated with SL wear has not, to the best of our knowledge, been determined. From a survey of SL practitioners, we estimated the period prevalence over 1 year of corneal complications that required SL wearers to discontinue lens wear. In a sample of 72,605 wearers, SL wear was discontinued for the following complications: corneal edema, 1.2%; corneal neovascularization, 0.53%; microbial keratitis, 0.45%; and limbal stem cell deficiency, 0.20%. This study design allowed for calculation of period prevalence of these complications rather than complication incidence rates. Information presented in this report may be useful in clinical decision-making and for future study design.

Current Trends in Scleral Lens Prescription, Management, and Evaluation.

OBJECTIVES: To report current trends in scleral contact lens prescription and management, including lens designs prescribed, care products recommended, and procedures performed during routine scleral lens (SL) evaluation. METHODS: An online survey was designed by the Scleral Lenses in Current Ophthalmic Practice Evaluation study team and administered to eye care practitioners attending a specialty contact lens meeting. The survey was available from November 8, 2019, through March 31, 2020. Participants' demographic data were collected, along with information on lens diameters, landing zone (LZ) designs, recommended care products, and components of routine SL evaluation. RESULTS: In total, 715 participants responded to at least one of the survey items of interest. Most lenses prescribed (63%) were 16 mm or more in diameter. Lenses with toric LZs were the most frequently prescribed (48%), followed by spherical (40%), quadrant-specific (8%), and impression-based or image-based designs (3%). Most participants (61%) recommended hydrogen peroxide products for lens care. Nonpreserved saline in a single-use vial was most frequently recommended to fill the bowl of the lens before application. Intraocular pressure was measured during SL evaluation by 45% of participants; 38% of participants routinely measured corneal thickness. CONCLUSIONS: Practitioners increasingly are prescribing SLs with advanced LZ designs. Most practitioners recommend hydrogen peroxide-based disinfection systems and single-use vials of nonpreserved saline for lens care and application. Because differences in components of routine SL evaluations were reported, clinicians may benefit from reaching a consensus on essential components of SL evaluation.

Trends in Scleral Lens Fitting Practices: 2020 Scleral Lenses in Current Ophthalmic Practice Evaluation Survey.

OBJECTIVES: To explore trends in demographic characteristics of scleral lens (SL) practitioners and primary indications for SL fitting over 5 years. METHODS: An online survey similar to the 2015 Scleral Lenses in Current Ophthalmic Practice Evaluation (SCOPE) study was designed and administered from November 8, 2019, through March 31, 2020, to attendees at two international contact lens meetings, members of the Scleral Lens Education Society, and participants in the 2015 SCOPE study. Practitioners reporting at least five completed SL fits were included in the analysis. RESULTS: Of 922 respondents, 777 had fit at least five SLs: 63% from the United States (59 other countries were represented), findings similar to the 2015 survey, in which 799 respondents (72%) were US-based and 49 from other countries. Most practitioners were in community practice (76%) than academic practice (24%). In 2015, 64% were in community practice and 36% in academic practice. A median of 84% of SLs were fit for corneal irregularity, 10% for ocular surface disease, and 2% for uncomplicated refractive error. In comparison, the 2015 indications were 74%, 16%, and 10%, respectively. The median number of fits completed per practitioner was 100 (range, 5-10,000; mean [SD] 284 [717]; n=752). In 2015, the median was 36 (range, 5-3,600; mean [SD] 125 [299]; n=678). CONCLUSIONS: The number of experienced SL practitioners is increasing, as is international representation. Most practitioners practice in community rather than academic settings. SLs continue to be primarily prescribed for corneal irregularity and are rarely used solely for correction of refractive error.

"Save the Vein" Initiative in Children With CKD: A Quality Improvement Study.

RATIONALE & OBJECTIVE: The preferred vascular access for hemodialysis recipients is an arteriovenous fistula in the nondominant arm. Prior placement of a peripheral intravenous (PIV) catheter can lead to vascular injury and limit options for arteriovenous fistula creation, a particular problem for children, who may need hemodialysis for their entire lifetime. We instituted an initiative to increase the frequency of PIV catheter placement in the dominant arm for hospitalized pediatric patients with advanced chronic kidney disease (CKD). STUDY DESIGN: Quality improvement initiative. SETTING & PARTICIPANTS: Children with CKD stage 3-5, receiving dialysis, and/or following kidney transplantation who were hospitalized at one children's hospital between September 2018 and August 2020. QUALITY IMPROVEMENT ACTIVITIES: Retrospective data on PIV catheter location for patients from January 1 to June 30, 2017, served as baseline data. Quality improvement activities consisted of: 1) education of the multidisciplinary treatment team, patients, and parents regarding importance of vein preservation; 2) placement of individualized notes in the electronic medical record identifying the preferred arm for PIV catheter placement; 3) use of "restricted extremity" arm bands; and 4) vascular access team participation to minimize attempts for PIV catheter placement. OUTCOME: Monthly compliance with placement of PIV catheters in dominant arms. ANALYTICAL APPROACH: Location of PIV catheter placements were determined monthly and used to create run charts describing compliance. RESULTS: At baseline and before institution of this initiative, 34 of 72 (47%) PIV catheters were placed in patients' dominant arms, with only 2 of 8 (25%) PIV catheters placed in the dominant arm for children aged<5 years. After instituting the initiative, 345 of 371 (93%) PIV catheters were placed in the dominant arm of 93 children; in children aged<5 years, 58 of 62 (94%) PIV catheters were placed in the dominant arm. Only 38 of 371 (10%) PIV catheters were placed in the antecubital vein. LIMITATIONS: Single-center study. CONCLUSIONS: Education regarding the importance of vein preservation, along with implementation of a standardized process for identifying children for whom vein preservation is important, can help direct PIV catheter placement and potentially preserve vasculature in pediatric patients with CKD.

Dry Eye Symptoms in Individuals With Keratoconus Wearing Contact Lenses.

OBJECTIVES: To assess dry eye symptoms associated with different contact lens modalities in patients with keratoconus using a dry eye questionnaire. METHODS: An online survey was distributed by the National Keratoconus Foundation. The survey asked participants to report demographic characteristics, current optical correction, age at the time of diagnosis of keratoconus, and contact lens history. The 12-item Ocular Surface Disease Index (OSDI) questionnaire was also completed. Data from participants wearing the same contact lens modality bilaterally were analyzed. RESULTS: The survey was completed by 197 individuals wearing the same contact lens modality bilaterally. The average age of participants at the time of the survey was 47.2±14.8 years (range: 15-87 years), and the average age at which keratoconus was diagnosed was 26.1±9.9 years (range: 8-55 years). The mean overall OSDI score of all participants was 40.2±22.8 (range: 0-100). There was no difference in the mean OSDI scores based on current contact lens modality type (F=1.79; n=187; P=0.13). Based on an OSDI score of 33 or higher, 90% of participants reported symptoms indicative of dry eye disease. Scleral lens wearers reported less discomfort on the individual items related to windy and low-humidity conditions. CONCLUSIONS: Individuals with keratoconus, irrespective of contact lens modality, report a high incidence of dry eye symptoms.

Keratoconus Patient Satisfaction and Care Burden with Corneal Gas-permeable and Scleral Lenses.

SIGNIFICANCE: Scleral lenses (SLs) are increasingly being considered as the initial correction for patients with keratoconus. In this study, keratoconus patients report higher levels of comfort and visual satisfaction with SL compared with corneal gas-permeable lenses (GPs). PURPOSE: This study aimed to compare patient satisfaction and care burden associated with GP and SL for the management of keratoconus. METHODS: An electronic survey was distributed by the National Keratoconus Foundation from October 2016 to March 2017. Age at diagnosis, initial and current treatment, lens complications, access to care, lens handling time, and annual out-of-pocket treatment costs were collected. Vision, lens comfort, and ease of use satisfaction were rated from 1 to 5. RESULTS: A total of 422 responses were received, including 75 bilateral GP and 76 bilateral SL wearers. Scleral lens wearers had greater satisfaction with vision (3.2 ± 1.1 [SL] vs. 2.6 ± 1.1 [GP]; P < .001) and comfort (3.3 ± 1.0 [SL] vs. 2.2 ± 1.2 [GP]; P < .001) but similar ease of use satisfaction in both groups (2.8 ± 1.1 [SL] vs. 2.7 ± 1.1 [GP]; P < .90). Both groups reported issues with cloudy or foggy vision (GP, 63%; SL, 58%) and contact lens discomfort (GP, 77%; SL, 67%). Although GP wearers reported more issues with lens movement or loss (40 [GP] vs. 18% [SL]), they had fewer difficulties with halos (53 vs. 72% [SL]) and lens handling (40%) compared with SL wearers (63%). Gas-permeable lens (48%) and SL (45%) wearers spend 6 to 10 minutes daily handling their lenses. Sixty percent of GP wearers reported annual out-of-pocket cost expenses less than U.S.$1000, whereas only 41% of SL wearers reported the same. CONCLUSIONS: Scleral lens wearers with keratoconus report greater satisfaction with vision and comfort than do GP wearers, although both groups reported cloudy vision and lens discomfort.

Comparison of Pneumatonometry and Transpalpebral Tonometry Measurements of Intraocular Pressure during Scleral Lens Wear.

SIGNIFICANCE: As scleral lens wear becomes more common, understanding the impact of these lenses upon ocular physiology is critically important. Studies on the effect of scleral lens wear upon intraocular pressure (IOP) have used different instruments and have reported conflicting results. PURPOSE: The purpose of this study was to compare assessment of IOP during scleral lens wear using pneumatonometry and transpalpebral tonometry. METHODS: Twenty healthy subjects wore a small-diameter (15.2 mm) and a large-diameter (18.0 mm) scleral lens on the right eye, each for 1 hour in randomized order. IOP was assessed with pneumatonometry and transpalpebral tonometry on both eyes before lens application, immediately after lens application, after 1 hour of lens wear, and immediately after lens removal. Paired t test compared mean IOP in the study eye to the control eye. Repeated-measures ANOVA was performed to take instrumentation, lens diameter, and their interaction into account in an analysis of the change in IOP in the study eye. RESULTS: Mean peripheral IOP measured with pneumatonometry was not significantly different from baseline at any subsequent measurement. Measurements with transpalpebral tonometry, however, were significantly different during scleral lens wear immediately after application and after 1 hour of wear with both diameter lenses (P < .005), but were not significantly different after either sized lens was removed. Repeated-measures ANOVA revealed that the instrument used to measure IOP was a significant factor in IOP changes found during lens wear (P ≤ .001). CONCLUSIONS: Assessment of IOP during scleral lens wear varies based upon the instrument that is used. Although further studies are clearly needed to further elucidate this issue, clinicians should continue to monitor optic nerve structure and function in scleral lens wearers, as they do in all patients.

Scleral Lenses in the Management of Corneal Irregularity and Ocular Surface Disease.

PURPOSE: To describe current practice patterns regarding the use of scleral lens therapy in the management of corneal irregularity and ocular surface disease among eye care providers who fit scleral lenses. METHODS: The Scleral Lenses in Current Ophthalmic Practice: an Evaluation (SCOPE) study group conducted an electronic survey of eye care providers from January 15 to March 31, 2015. Respondents ranked management options for corneal irregularity in the order in which they would generally consider their use. Respondents also ranked options for the management of ocular surface disease in the order in which they would use each of the treatments. Results for each option were analyzed as percentage first-place ranking; percentage first-, second-, or third-place ranking; and mean rank score. RESULTS: Survey responses were obtained from 723 providers who had fit 5 or more scleral lenses. Of these respondents, 629 ranked options for management of corneal irregularity and 612 ranked options for management of ocular surface disease. Corneal rigid gas-permeable lenses were the first option for management of corneal irregularity for 44% of respondents, and scleral lenses were the first option for 34% of respondents. Lubricant drops were the first therapeutic recommendation for ocular surface disease for 84% of respondents, and scleral lenses were ranked first by 6% of respondents. CONCLUSION: Scleral lenses rank second only to corneal rigid gas-permeable lenses for management of corneal irregularity. Scleral lenses are generally considered after other medical intervention and before surgery for the management of ocular surface disease.

Demographic Characteristics and Prescribing Patterns of Scleral Lens Fitters: The SCOPE Study.

OBJECTIVES: This study reports demographic characteristics of scleral lens providers and indications for scleral lens prescription as assessed by a worldwide online survey. METHODS: The Scleral Lenses in Current Ophthalmic Practice: an Evaluation (SCOPE) study group designed the online survey regarding current scleral lens prescription and management practices. The Mayo Clinic Survey Research Center administered the survey, which was open from January 15 to March 31, 2015. Data from 989 responses were collated by the Survey Research Center and deidentified before analysis. Responses of individuals who had fit at least five patients with scleral lenses were analyzed in detail. RESULTS: Most lens fitters were men (61%, n=800). Of survey respondents, 29% were 25 to 34 years; 22%, 35 to 44 years; 22%, 45 to 54 years; and 26%, more than 55 years (n=806). For 29% of all respondents, professional training was completed between 2009 and 2014 (n=804). Most (54%) fit their first patient between 2010 and 2015, with the earliest lens fit reported in 1956 (n=634). Most respondents (63%) worked primarily in private, group, or retail practice (n=811). Scleral lenses were most often prescribed for corneal irregularity (74%), followed by ocular surface disease (16%) and uncomplicated refractive error (10%) (n=673). CONCLUSIONS: Eye care providers of all ages are fitting scleral lenses. The number of individuals who fit this lens modality has increased during the past decade. Scleral lenses are being fit by providers in a wide range of practice settings. Most scleral lenses are prescribed for corneal irregularity.

Scleral Lens Prescription and Management Practices: The SCOPE Study.

OBJECTIVES: To assess current scleral lens prescription and management practices by conducting an international online survey of eye care providers. METHODS: The SCOPE (Scleral Lenses in Current Ophthalmic Practice: an Evaluation) study group designed and administered an online survey regarding current scleral lens prescription and management practices. The survey was open from January 15 to March 31, 2015, and generated 723 responses from individuals who had fit at least 5 patients with scleral lenses. RESULTS: Respondents (n=663) prescribed scleral lenses that ranged from 15 to 17 mm in diameter (65%), smaller than 15 mm (18%), and larger than 18 mm (17%). More than 50 lens designs were identified. Average daily wearing time of 11.8 hr was consistent across 651 respondents, and 475/651 (73%) recommended midday removal on some, most, or all days. Most respondents recommended nonpreserved saline to fill the bowl of the lens before application (single-use vials, 392/653 [60%]; bottled products, 372/653 [57%]). A hydrogen peroxide-based disinfection system was the most commonly recommended care product (397/651 [61%]). CONCLUSIONS: A reasonable degree of consensus exists regarding some aspects of scleral lens prescription and management (average lens diameter, daily wearing time, and use of nonpreserved products for lens application). Further study is needed to develop evidence-based guidelines for scleral lens prescription and management.

Effects of acute peripheral/central visual field loss on standing balance.

Vision impairments such as age-related macular degeneration (AMD) and glaucoma are among the top risk factors for geriatric falls and falls-related injuries. AMD and glaucoma lead to loss of the central and peripheral visual fields, respectively. This study utilized a custom contact lens model to occlude the peripheral or central visual fields in healthy adults, offering a novel within-subject approach to improve our understanding of the etiology of balance impairments that may lead to an increased fall risk in patients with visual field loss. Two dynamic posturography tests, including an adapted version of the Sensory Organization Test and a virtual reality environment with the visual scene moving sinusoidally, were used to evaluate standing balance. Balance stability was quantified by displacement and time-normalized path length of the center of pressure. Nine young and eleven older healthy adults wore visual field occluding contact lenses during posturography assessments to compare the effects of acute central and peripheral visual field occlusion. The results found that visual field occlusion had greater impact on older adults than young adults, specifically when proprioceptive cues are unreliable. Furthermore, the results suggest that both central and peripheral visions are important in postural control; however, peripheral vision may be more sensitive to movement in the environment.

Top-down influence on the visual cortex of the blind during sensory substitution.

Visual sensory substitution devices provide a non-surgical and flexible approach to vision rehabilitation in the blind. These devices convert images taken by a camera into cross-modal sensory signals that are presented as a surrogate for direct visual input. While previous work has demonstrated that the visual cortex of blind subjects is recruited during sensory substitution, the cognitive basis of this activation remains incompletely understood. To test the hypothesis that top-down input provides a significant contribution to this activation, we performed functional MRI scanning in 11 blind (7 acquired and 4 congenital) and 11 sighted subjects under two conditions: passive listening of image-encoded soundscapes before sensory substitution training and active interpretation of the same auditory sensory substitution signals after a 10-minute training session. We found that the modulation of visual cortex activity due to active interpretation was significantly stronger in the blind over sighted subjects. In addition, congenitally blind subjects showed stronger task-induced modulation in the visual cortex than acquired blind subjects. In a parallel experiment, we scanned 18 blind (11 acquired and 7 congenital) and 18 sighted subjects at rest to investigate alterations in functional connectivity due to visual deprivation. The results demonstrated that visual cortex connectivity of the blind shifted away from sensory networks and toward known areas of top-down input. Taken together, our data support the model of the brain, including the visual system, as a highly flexible task-based and not sensory-based machine.

Diffusion of Antimicrobials Across Silicone Hydrogel Contact Lenses.

OBJECTIVES: To measure the diffusion of topical preparations of moxifloxacin, amphotericin B (AmB), and polyhexamethylene biguanide (PHMB) through silicone hydrogel (SH) contact lenses (CLs) in vitro. METHODS: Using an in vitro model, the diffusion of three antimicrobials through SH CLs was measured. Diffused compounds were measured using a spectrophotometer at set time points over a period of 4 hr. The amount of each diffused antimicrobial was determined by comparing the experimental value with a standard curve. A biological assay was performed to validate the CL diffusion assay by testing antimicrobial activity of diffused material against lawns of susceptible bacteria (Staphylococcus epidermidis) and yeast (Saccharomyces cerevisiae). Experiments were repeated at least two times with a total of at least four independent replicates. RESULTS: Our data show detectable moxifloxacin and PHMB diffusion through SH CLs at 30 min, whereas AmB diffusion remained below the limit of detection within the 4-hr experimental period. In the biological assay, diffused moxifloxacin demonstrated microbial killing starting at 20 min on bacterial lawns, whereas PHMB and AmB failed to demonstrate killing on microbial lawns over the course of the 60-min experiment. CONCLUSIONS: In vitro diffusion assays demonstrate limited penetration of certain anti-infective agents through SH CLs. Further studies regarding the clinical benefit of using these agents along with bandage CL for corneal pathologic condition are warranted.