Takashi Itokawa

Background: Thermal pulsation (LipiFlow) warms the eyelids from the palpebral conjunctival surface. However, temperature and blood flow responses across multiple ocular-surface locations have not been systematically evaluated in a clinical cohort of patients with meibomian gland dysfunction (MGD). We examined changes in ocular surface temperature, blood flow and non-invasive tear break-up time (NIBUT) after LipiFlow in patients with MGD. Methods: Thirteen patients (3 men, 10 women; mean age, 64.9 ± 18.1 years) with MGD were included. The temperature and blood flow of the upper and lower eyelid skin and the palpebral and bulbar conjunctiva, along with the NIBUT, were measured before, 5 min after and 1 month after LipiFlow. The change from baseline was analyzed with Steel’s test. Results: All locations changed significantly 5 min after the treatment: the temperature rose by 1.13–1.21 °C, the blood flow increased to 1.24–1.45 times the baseline value, and NIBUT increased by 3.1 ± 2.7 s. At 1 month, temperature had returned to baseline at all locations, and blood flow had largely returned toward baseline, although bulbar conjunctival blood flow remained significantly elevated; NIBUT remained significantly longer than before treatment. Conclusions: Thermal pulsation warmed the ocular surface, including the palpebral conjunctiva where the meibomian glands are located. The improvement in tear film stability persisted for 1 month despite the largely transient temperature and blood flow responses.

Purpose: To investigate temporal changes in parameters associated with tear film stability after instillation of long-acting 3% diquafosol ophthalmic solution (DQS LX), which contains polyvinylpyrrolidone. Study Design: Prospective crossover study design. Methods: We enrolled 23 eyes of 23 soft contact lens (SCL) wearers (aged 25.3 ± 4.4 years). One-day disposable silicone hydrogel lenses (narafilcon A) were used in this study. DQS LX was instilled without a SCL on the first day. On the other two days, subjects received DQS or DQS LX at 7 h after wearing SCLs. Tear meniscus height (TMH), non-invasive tear break-up time (NIBUT) and ocular surface temperature (OST) were measured before and at 5, 15, 30, 45, 60, 80 and 120 min after instillation. Results: When not wearing SCLs, DQS LX instillation significantly improved TMH for up to 120 min and NIBUT for up to 80 min. When wearing SCLs, DQS and DQS LX instillation significantly increased TMH for up to 45 and 80 min, and NIBUT for up to 15 and 30 min. Compared to DQS, DQS LX administration resulted in a significantly higher TMH at 5, 60 and 80 min, as well as a significantly prolonged NIBUT at 5 and 60 min. OST with and without SCLs also varied depending on the changes in the parameters associated with tear film stability. Conclusion: Compared to DQS, when wearing SCLs, DQS LX was found to increase the amount of tear fluid and improve tear film stability for longer periods.

Half of the individuals who wear contact lenses use reusable lenses that require proper care. Improper contact lens (CL) care and using inadequate disinfecting solutions can lead to lens contamination, CL-related microbial keratitis, and Acanthamoeba keratitis. Oxidative disinfecting solutions, such as hydrogen peroxide, show higher efficacy than multipurpose solutions. Povidone–iodine (PVP-I), an oxidative disinfectant used in ophthalmic surgery, has been proven to be safe and effective. The PVP-I system, a CL disinfecting solution developed in Japan, has demonstrated excellent antimicrobial and antiviral properties. Although CL discomfort does not have a risk of ocular disorders with poor visual prognosis, such as keratitis, CL discomfort can still lead to lens dropout and thus needs to be addressed. To mitigate CL discomfort, it is essential to use disinfecting solutions containing surfactants and wetting agents that improve wettability of the lens surface. A CL solution containing hyaluronic acid derivatives (HADs) as wetting agents that permanently adhere to the lens surface to improve wettability of the lens surface was developed in Japan. There is potential for HAD to be integrated into various solutions. This article reviews the efficacy of novel PVP-I–based disinfecting solution and HAD wetting agents.

Objective: To evaluate the lubricating effect of hyaluronic acid (HA) on soft contact lenses (SCLs) measured using a pendulum-type friction tester. Methods: We measured the coefficient of friction (CoF) of narafilcon A, delefilcon A, and etafilcon A with polyvinylpyrrolidone (PVP), daily disposable SCL material, using a modified pendulum-type friction tester. Sample SCLs were set on an acrylic plastic half-ball and placed into the polyethylene terephthalate hemisphere cup filled with 0.4 mL of test lubricants that included saline and 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% (wt/vol) HA (molecular weight, 850 kDa). The viscosities of saline and HA were measured using an Ubbelohde viscometer. Results: The CoF of the SCL under a low concentration (0.05%) of HA was the lowest and significantly lower than saline in narafilcon A and delefilcon A (PP9.286X). Conclusion: The viscosity of a high concentration of HA may increase the friction of SCLs, which may have a deleterious effect on the ocular surface.

Purpose: Prelens tear film stability of soft contact lens (SCL) play an important role for contact lens discomfort. In this study, we investigated the association between two types of noninvasive methods and evaluated the tear film stability with SCL using the methods. Patients and Methods: In experiment 1, images of ring mire were recorded with a keratograph after focusing the pigment located at the front or back of the SCL. Interferometry and videokeratoscopy were used for the assessment of tear film stability in the right eye of 10 women, with two different cosmetic daily disposable SCLs: polymacon and etafilcon A with polyvinylpyrrolidone. Time to first distortion by noninvasive keratograph break up time (NIKBUT-first) was compared to noninvasive interferometry break up time (NIBUT). In experiment 2, ten normal females wore two different daily disposable SCLs: samfilcon A and narafilcon A. NIKBUT-first and NIBUT were compared between the lenses after 8 hours of SCL wearing. Results: In experiment 1, NIBUT-first without SCL was significantly correlated to NIBUT without SCL (r=0.445, P=0.0488, Pearson’s correlation coefficients). However, NIKBUT-first with SCL was not significantly correlated with NIBUT with SCL. In experiment 2, although NIKBUT-first was not significantly different between SCLs, samfilcon A had significantly longer NIBUT than narafilcon A (P=0.0315, paired t-test). Conclusion: NIKBUT-first with SCL could be related to tear film stability between the lens and the corneal surface, but not to prelens tear film stability. NIIBUT could be a suitable method to evaluate prelens tear stability.

Purpose. To compare two platelet-rich plasma (PRP) preparation methods (double spin (D-PRP) and TriCell PRP (T-PRP)) for eye drops, concentration yields of platelets and other cells, release of growth factors, and efficacy of the de-epithelization rabbit model. Methods. PRP was extracted by D-PRP and T-PRP from 30 ml blood from healthy adults. After extraction, platelets and leukocytes were counted. D-PRP and T-PRP were preserved during A: 1 h storage at room temperature, B: 1 h storage at −20°C, C: 24 h storage at 4°C, and D: 24 h storage at −20°C. Platelet-derived growth factor (PDGF) was measured. Freezing/thawing PRP eye drops and control were instilled in the de-epithelization rabbit model four times per day for 5 days. Histology was compared between eyes treated with control, D-PRP, and T-PRP. Results. 14 ml of D-PRP and 4 ml of T-PRP were extracted from 30 ml whole blood samples. D-PRP and T-PRP had 41.36 ± 8.43 × 10⁴ and 67.02 ± 13.55 × 10⁴ platelets and 0.41 ± 0.24 × 10³/ml and 10.09 ± 4.29 × 10³/ml leucocytes, respectively. In the four storage methods, PDGF concentrations in T-PRP were higher than those in D-PRP eye drops. Freezing/thawing D-PRP and T-PRP increased PDGF concentrations. Histology showed corneal epithelium thickness in T-PRP-treated eyes after healing (38.41 ± 9.10 μm) was significantly higher than that in control-treated (27.77 ± 4.76 μm) and D-PRP-treated eyes (18.32 ± 3.14 μm) ( < 0.05). There was no corneal damage with inflammation in corneal stroma and epithelium of all tested groups. Electron microscopy revealed strong adhesion between cell junctions in T-PRP-treated eyes. Conclusions. Freezing/thawing of PRP extracted with the T-PRP kit may result in high platelet and leukocyte concentration and produce high PDGF concentration. PRP eye drops including leucocytes could increase thickness of corneal epithelium without corneal inflammation.

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.

Objective: 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 (PPPP<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.