Kinetic photovoltage along semiconductor-water interfaces

External photo-stimuli on heterojunctions commonly induce an electric potential gradient across the interface therein, such as photovoltaic effect, giving rise to various present-day technical devices. In contrast, in-plane potential gradient along the interface has been rarely observed. Here we show that scanning a light beam can induce a persistent in-plane photoelectric voltage along, instead of across, silicon-water interfaces. It is attributed to the following movement of a charge packet in the vicinity of the silicon surface, whose formation is driven by the light-induced potential change across the capacitive interface and a high permittivity of water with large polarity. Other polar liquids and hydrogel on silicon also allow the generation of the in-plane photovoltage, which is, however, negligible for nonpolar liquids. Based on the finding, a portable silicon-hydrogel array has been constructed for detecting the shadow path of a moving Cubaris. Our study opens a window for silicon-based photoelectronics through introducing semiconductor-water interfaces.

Clinical Observation of Silicon Hydrogel Contact Lens Fitted Immediately after Small Incision Lenticule Extraction (SMILE)

Purpose. To examine the immediate use of bandage contact lenses (BCLs) for improving patient comfort after small incision lenticule extraction (SMILE) surgery. Methods. This is a prospective randomized controlled study in which one hundred and seventy-eight patients undergoing SMILE were randomly allocated to three groups: group A wore BCLs for 8 hours postsurgery, group B wore BCLs for 24 hours postsurgery, and group C did not wear any BCLs postsurgery. Eight subjective symptoms including photophobia, tearing, pain, foreign body sensation, burning, blurred vision, sting, and dry eyes were prospectively evaluated at 2 hours, 4 hours, 8 hours, and 24 hours, using a questionnaire with a total score of 24. The scores of symptoms and signs were compared between the three groups. Results. There was a statistically significant time effect on scoring, which implicated a decline in symptoms over time after surgery (P<0.001). There was also a significant interaction between time and the treatment group (P<0.01). The total symptom score of groups A and B (5.85 ± 3.97 and 5.99 ± 4.67, respectively) was significantly lower than that of group C at 2 hours postsurgery (7.35 ± 4.86, P<0.05), especially in tearing and pain (P<0.05). The level of corneal oedema at 24 hours postsurgery was also statistically significantly different between the three groups (P<0.001), and the post hoc test showed that groups A and B were lower than group C (P<0.01). Conclusion. Silicon hydrogel BCLs applied immediately after SMILE surgery can relieve postsurgical symptoms of tearing and pain, improving overall patient comfort, and reduce corneal oedema. This trial is registered with ChiCTR-ONRC-13003114. Precis. The application of silicone hydrogel bandage contact lenses immediately after SMILE surgery has the potential to improve patient comfort, corneal healing, and patient satisfaction following SMILE.

WETTABILITY – ANOTHER PARAMETER FOR GOOD FITTING OF A SILICONE-HYDROGEL DAILY DISPOSABLE CONTACT LENS

The modern world is very fast and dynamic. Consumer requirements rise to every commodity part of their everyday life - food, clothing, cosmetics, and medical devices. Eye care and eye health are also part of them. Companies producing contact lenses work daily to improve the safety and comfort of wearing, as well as on the technical characteristics of the material (type of material, wear time, module, Dk / t etc.). Silicon hydrogel contact lenses (SiHy) were introduced almost two decades ago. At that time it was estimated that there are about 70 million contact lenses all over the world. Since then, their number has doubled and a significant majority now have silicone-hydrogel contact lenses, resulting in a steady and noticeable reduction in the number of regular hydrogel lenses. When the first one-day silicon-hydrogel contact lenses were introduced in 2008, they were announced as breakthroughs in technology. When they were introduced to the market, they were presented in spherical, toric and multifocal designs, which led to a significant increase in the use / prescription of silicon-hydrogel daily disposable contact lenses. A survey conducted in 2014 by the International Consortium illustrates this point. Although, according to this study, the use of SiHy contact lenses varies widely across the world. In the United States, Canada, Australia and the United Kingdom, four to six times more patients were fitted with silicone-hydrogel CLs compared to hydrogels in 2014 and in each country, daily disposable SiHy contact lenses were prescribed with a larger frequency compared to daily disposable hydrogel lenses. It is important to make a good fit to ensure and increase the comfort of wearing contact lenses. In addition to some of the standard fitting techniques such as: keratometry and choice of base curve of the lens; size and eccentricity; an assessment of the mobility of a lens placed in the eye - look positions, mobility, push up test, can be added and the wetting of the contact lens. Even in perfect fit, if the lens does not interact well with the tear film, it would lead to complaints and discomfort in the patient. The degree of wetting is determined by the balance between adhesive and cohesive forces acting on the surface of the lens. CLs, which can support full wetting, allow a tight coating of the tear film, a smooth recovery of the tear layer after eyelid opening and good visual acuity. The interaction between CL, eye surface and tear film is vital to their successful fit. It has long been known that both the organic and inorganic components of the tear film and anterior surface of the eye can deposit deposits on the contact lenses. There are various non-invasive methods for assessing the tear film and, above all, the lipid layer. Some of these are Non invasive breakup time (NIBUT) and specular biomicroscopy. In the present work we will look at daily disposable silicone-hydrogel contact lenses that have been tested in vivo for good wetting, stability and good regeneration of the tear film.