Reduction of Blue Light Emission in Internet-protocol Television and Its Effect on Ocular Fatigue

PURPOSE: The blue light emitted from electronic devices may be harmful to the eye. We investigated whether internet-protocol television (TV) with lowered blue light emission reduced ocular fatigue. METHODS: A total of 98 healthy subjects were recruited. They watched an animated movie (A) and an identical version except for reduced blue light (B), sequentially for 1 hour in random order. Before and after watching the movies, we measured the distance and near refraction and tear break-up time objectively. Ocular discomfort score and the earliest onset time of the ocular fatigue symptoms were also measured using our specially designed subjective ocular discomfort scale. RESULTS: The median age of the participants was 28.5 years, and there were 56 females out of 98 total participants. Both distance and near refraction were not significantly different before versus after watching the movies, nor between viewing movies A and B. However, the accommodative amplitude measured by subtracting the near refraction from the distance refraction was found to be greater after watching movie B compared with movie A in a subset of subjects with hyperopia [1.92 vs. 1.72 diopters (D) for the right eye and 2.14 vs. 1.83 D for the left eye; p = 0.04 and p < 0.01, respectively]. The ocular discomfort score was lower (15.40 vs. 12.85; p = 0.10), but not significantly, and the earliest ocular fatigue onset time was significantly delayed (23.48 vs. 34.51 minutes; p < 0.01), after watching movie B. CONCLUSIONS: Reduction of blue light emission alleviated ocular fatigue caused by TV displays. Watching TV with lower blue light may provide benefits to hyperopic individuals by reducing eye strain and improving the accommodative amplitude.

The Effect of a Fixed Combination of 0.0015% Tafluprost-0.5% Timolol in Normal Tension Glaucoma Patients

PURPOSE: This study evaluated the effect of a fixed combination of 0.0015% tafluprost-0.5% timolol (Tapcom®, Santen, Osaka, Japan) in glaucoma patients. METHODS: This study included 23 patients who were diagnosed with normal tension glaucoma and treated with a fixed combination of 0.0015% tafluprost-0.5% timolol as the first therapy. Diurnal intraocular pressure (IOP) was measured every 2 and 0.5 hours between 9:00 am and 4:30 pm. The IOP change with respect to body position (positional IOP) was measured at baseline and at 6 months after eye-drop instillations. IOP fluctuation was defined as the standard deviation of IOP measurements. Throughout the study, all side effects were recorded and monitored by the investigators. RESULTS: The mean reduction in IOP in the 0.0015% tafluprost-0.5% timolol fixed combination-treated eyes was −3.37 ± 2.39 mmHg (−19.70 ± 13.97%) for the right eye and −3.22 ± 2.27 mmHg (-18.81 ± 13.28%) for the left eye (paired t-test, p < 0.001). The mean positional IOP measured at 4 pm at 6 months after 0.0015% tafluprost-0.5% timolol fixed combination instillation showed statistically significant reduction from the mean positional IOP at baseline. There was a significant difference in the number of patients with ≤3 mmHg IOP variation over four time points between baseline and at 6 months in the 0.0015% tafluprost-0.5% timolol fixed combination-treated eyes (McNemar test, p < 0.001). There was no serious adverse event causing ocular damage. CONCLUSIONS: Use of 0.0015% tafluprost-0.5% timolol fixed combination was effective and well tolerated in reducing IOP and in maintaining its effectiveness in glaucoma patients.

Wear of Retrieved UHMWPE Hip Liners

After the gamma-irradiation sterilization, the most widely used orthopaedic grade polymer bearing liner material for the total joint replacement, ultra-high molecular weight polyethylene (UHMWPE), degrades through the progressive in vivo oxidation. The oxidative degradation makes UHMWPE brittle and leads to reduction of its mechanical properties. In this study, the effect of the in vivo post-irradiation ageing time on the wear of UHMWPE was investigated. Twelve retrieved polyethylene hip liners implanted for 3-16 years and then stored in the air for 1.5-8 years were used. Two types of the pin-on-disk wear testing were conducted. The uni-directional repeat pass rotating and the linear reciprocating wear testing were done with stainless steel disks against stationary polyethylene pins under 4MPa at 1Hz with bovine serum lubrication. Wear of the retrieved polyethylene hip liners does not have significant correlation with the in vivo or total ageing time. The linear reciprocal sliding motion generated a more pronounced wear than the uni-directional repeat pass sliding motion. This indicates that the kinematic motion significantly affects the wear of aged UHMWPE, having a brittle, white band region.