Biomedical subjects

Joseph G Vehige

Publications and source records attributed to Joseph G Vehige.

3 recordsLinked to original sources

PubMed2007

A pre-application drop containing carboxymethylcellulose can reduce multipurpose solution-induced corneal staining.

PURPOSE: Use of polyhexanide based multipurpose solutions (MPSs) for contact lens disinfection has been linked to low-grade corneal staining. In vitro data suggest that carboxymethylcellulose (CMC) may neutralize polyhexanides. The purpose of this investigation was to determine whether a pre-application drop of CMC reduces polyhexanide staining in vivo. METHODS: Thirty adapted soft contact lens (SCL) wearers participated in this investigator-masked, randomized, two-way cross-over study. Subjects wore a new Group II lens (alphafilcon A, 66% water) daily for 4 weeks and disinfected lenses using a MPS containing 0.0001% polyaminopropyl biguanide. A lens lubricant containing either CMC or povidone as the primary viscolyzer was applied to the lens each day before lens wear. Biomicroscopic signs and symptomatology were assessed. The difference in scores, 0 to 4 weeks and the difference between lubricants were analyzed. RESULTS: The cumulative fluorescein staining scores for combined eyes demonstrated a significant increase over time (e.g., cumulative staining score; p=0.004 and p<0.001 for CMC and povidone, respectively, matched pairs t-test, two-tailed), suggesting that for both lubricants the staining worsened with wear. This effect was expected and likely driven by the MPS. However, the mean cumulative staining scores for CMC and povidone were 2.8 and 2.6 out of 20 possible at baseline, increasing to 4.9 and 7.1 at 4 weeks, respectively. The increases were significantly different (p=0.003, matched pairs t-test, two-tailed) suggesting a greater increase in corneal staining for the povidone lubricant. The symptom scores were not significantly different, 0 to 4 weeks by regimen or between preinstillation drops. CONCLUSIONS: These results suggest that a CMC-containing preapplication drop can reduce corneal staining resulting from disinfection with a polyhexanide MPS. This result is consistent with a proposed mechanism for CMC to neutralize cationic disinfectants and may offer clinicians another means to reduce this type of corneal staining.

Adult↗

PubMed2004

The influence of lens conditioning on signs and symptoms with new hydrogel contact lenses.

BACKGROUND: Daily disposable contact lenses are considered to be the pinnacle of safe contact lens wear, yet it has been suggested that it takes some period of wear for the lens surface to reach optimal compatibility with the ocular surface. This study assesses the influence of brief treatment with a conditioning drop on the ocular response to new contact lenses over a single day of wear. METHODS: The study was a single-masked, paired (contralateral) comparison of the signs and symptoms with wear of new Acuvue 2 contact lenses pretreated with a conditioning agent containing carboxymethylcellulose (carmellose, CMC) against new lenses inserted directly from the blister pack. Sixty-one subjects participated in the study, of whom 59 were considered eligible for data analysis. Subjects were also divided into symptomatic and asymptomatic lens wearers based on their overall comfort level in lens wear. Symptoms and signs were recorded at lens delivery and following eight hours of wear. RESULTS: A set of slitlamp signs, comprising corneal staining (p <0.05), limbal redness (p <0.05), bulbar conjunctival hyperaemia (p <0.05), bulbar conjunctival staining (p <0.01) and palpebral conjunctival redness (p <0.05) showed small but statistically significant (p <0.05) end-of-day mean values in favour of the lens that was conditioned with the rewetting agent. These data were supported by the proportion of subjects showing lower gradings with conditioned lenses versus unconditioned lenses, as follows: corneal staining (35 per cent versus 12 per cent, p <0.05), limbal redness (43 per cent versus 22 per cent, p <0.05), bulbar conjunctival hyperaemia (50 per cent versus 15 per cent, p <0.05), bulbar conjunctival staining (46 per cent versus 30 per cent, p <0.1) and palpebral conjunctival hyperaemia (28 per cent versus 17 per cent, NS). For those subjects reporting symptoms with lens wear (n=12), there was a statistically significant (p <0.05) preference in terms of comfort as a result of preconditioning. CONCLUSIONS: The results of the investigation suggest that use of a conditioning agent can provide a more physiologically suitable environment for a new lens, thereby reducing the clinical signs associated with lens discomfort. The protocol used here, which is based on a statistical paradigm using standard pictorial grading scales, allows high sensitivity in detecting small changes in ocular parameters.

Adult↗

PubMed2003

Cytoprotective properties of carboxymethyl cellulose (CMC) when used prior to wearing contact lenses treated with cationic disinfecting agents.

PURPOSE: Disinfecting agents found in current multipurpose solutions (MPS) may produce low-grade ocular surface insults. This study investigates the potential for carboxymethylcellulose (CMC) to chemically complex residual disinfectants in situ. METHODS: The chemical availability of the MPS disinfectant polyhexamethylene biguanide (PHMB) was examined using a spectrophotometric assay. PHMB bioactivity was assessed by survival of bacteria in the presence of MPS with varying amounts of added CMC. RESULTS: Chemical availability of PHMB in water or MPS was reduced within 10 minutes of adding CMC. With the addition of CMC to MPS, survival rates for bacteria improved substantially, depending on the bacterial species, concentration, and exposure time. CONCLUSIONS: Carboxymethylcellulose rapidly binds PHMB and reduces its chemical availability and bioactivity. These results suggest a potential cytoprotective effect of CMC on the ocular surface when used before lens insertion.

Biguanides↗