PURPOSE. The purpose of this study was to investigate the uptake and the release of antibiotics from a newly synthesized drug delivery hydrogel soft contact lens (SCL) using an ion ligand mechanism.METHODS. The antibiotics used were Gatifloxacin (GFLX) and Moxifloxacin (MFLX). The uptake amount and the sustained-release kinetics of antibiotics were investigated in vitro, and were also compared with newly synthesized SCLs, etafilcon A and polymacon. The antibiotic concentrations in the cornea, aqueous humor, and crystalline lens, and the effect against bacterial proliferation were investigated in vivo using rabbit subjects. Additionally the drug release efficacy of the new SCL was compared with that of eye drop administrations.RESULTS. In vitro, antibiotic uptake was increased with the weight percent (wt%) of the anionic group, and the released amount of antibiotics was highest during the initial 1 hour period, which then decreased over the next 72 hours. The released antibiotics volume of the new SCLs was significantly higher throughout 72 hours than that of the other two materials, etafilcon A and polymacon (P < 0.01). Whereas in vivo, the concentrations found in the cornea and aqueous humor were higher than those for the eye drop groups (P < 0.05 or P < 0.01). Antibiotic release at those sites decreased over 72 hours. No bacterial populations were detectable in the group treated with the new SCL presoaked in antibiotics throughout the experimental periods. CONCLUSIONS.The new SCLs released the antibiotics over several days, and showed improved penetration into the eye, along with prevention of bacterial proliferation.

The changes in OST over SCLs are related to tear film stability. Measurements of OST can be used to evaluate tear film stability for SCL wearers.

Purpose: To determine a correlation between temperature and blood flow in the ocular anterior segment, and their effects on corneal temperature. Methods: In experiment 1, we recruited 40 eyes and measured the temperature and blood flow in the ocular anterior-segment (upper/lower eyelid skin, palpebral and bulbar conjunctiva, and cornea) before and after application of warm compresses. In experiment 2, we recruited 20 eyes and measured the same tissues before and during stimulation using water and capsaicin solution in the oral cavity. Results: In experiment 1, the temperatures of the upper/lower eyelid skin and cornea increased significantly until 15 min after the application of the warm compress; the temperatures of the palpebral and bulbar conjunctiva increased significantly until 10 min. The blood flow in the upper/lower eyelid skin and bulbar conjunctiva increased significantly until 10 min, and that of the palpebral conjunctiva increased significantly until 15 min. In experiment 2, the temperatures were correlated significantly with the blood flow in the upper and lower eyelid skin and palpebral and bulbar conjunctiva. The temperature of all locations and palpebral conjunctival blood flow contributed independently to the corneal temperature. Conclusions: In the ocular anterior segment, the temperature and blood flow were correlated significantly, and contributed to the corneal temperature.

To evaluate the interaction between tear supplements and soft contact lenses (SCLs), we measured the contact angles (CAs) on the SCLs using commercially available tear supplements. Methods: We used four daily disposable conventional hydrogel lenses (etafilcon A, etafilcon A+ polyvinylpyrrolidone, nelfilcon A, and omafilcon A containing 2-methacryloyloxyethyl phosphorylcholine [MPC]) and four silicone hydrogel lenses (narafilcon A, senofilcon A, delefilcon A, and stenfilcon A). The CAs on the SCLs were measured using a sessile drop technique and four different types of sessile drops, including saline, artificial tears, lubricants containing 2-MPC (MPC solution), and 0.1% hyaluronate acid (HA). Results:The CA values associated with the silicone hydrogel lenses were significantly (P,0.001) lower than those associated with the conventional hydrogel lenses with all four solutions. The mean CA of 0.1% HA was significantly (P,0.01) higher than that of saline. The mean CA of the MPC solution was significantly (P,0.01) lower than that of saline with the conventional hydrogel lenses but significantly (P,0.05) higher than that of saline with the silicone hydrogel lenses. Conclusions: The CAs associated with the silicone hydrogel SCLs were higher with the use of the MPC solutions and HA in vitro. The measured CAs may depend on ingredient agents, surface treatment of the CLs, and components of the tear supplements.

Purpose. To investigate the association among the ocular surface temperature (OST), tear film stability, functional visual acuity (FVA), and blink rate in patients after cataract surgery. Methods. We recruited 98 eyes of 69 patients (mean age, 73.7 ± 5.2 years) 1 month after phacoemulsification with implantation of acrylic intraocular lenses and assessed slit-lamp microscopy, corrected distance VA, FVA, noninvasive tear breakup time (NIBUT), and OST. We defined the changes in the OST from 0 to 10 seconds after eye opening as the ΔOST. We measured the FVA and blink rate using the FVA measurement system. We divided the patients into two groups based on tear film stability: stable tear film (NIBUT, >5.0 seconds) and unstable tear film (NIBUT, ≤5.0 seconds). We evaluated the differences between the two groups and the association between the blink rate and other clinical parameters. Results. The unstable tear film group (56 eyes) had significantly (p<0.0001, unpaired t-test) shorter NIBUTs than the stable tear film group (42 eyes). The ΔOSTs and blink rates were significantly (p<0.0001) higher in the unstable tear film group than in the stable group. Linear single regression analysis showed that the ΔOST (r = −0.430, p<0.0001), NIBUT (r = −0.392, p<0.0001), and gender (r = −0.370, p=0.0002) were correlated significantly with the blink rate. Multiple regression analysis showed that the ΔOST independently contributed to the blink rate. Conclusions. The frequency of blinks is associated with tear film stability in patients after cataract surgery. The blink rate may be useful for evaluating the tear film stability in clinical practice. The ΔOST should be an important contributing factor to the blink rate. [This trial is registered with UMIN000026970].