2023-09-13 14:56:46
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【免費乾眼症網上問卷（OSDI）】長期戴con或者喺冷氣地方，雙眼又乾又痕，唔通係乾眼症？想知道您有冇乾眼症，不如做個網上問卷啦！ 立即進行網上測試，搵出乾眼根源:
乾眼症往往令人聯想到眼藥水。坊間的藥房有林林總總的眼藥水可供選擇，有些含有防腐劑、有些標榜無添加防腐劑、部分潤眼產品的黏度不一，可以是眼藥水或潤眼凝膠或啫喱、亦有些含有血管收縮劑改善眼紅症狀，因應不同品牌或功能，這些產品在價格方面有極大差異。要治療乾眼症，眼藥水並非單一治療選項。在家熱敷、使用加濕器等亦有助改善乾眼症狀，眼科醫生診所亦可提供乾眼症相關治療如淚管栓塞、擠壓瞼板腺、強脈衝光治療（IPL）等。
不過，眼藥水毋須處方及容易購買，因此仍然是乾眼症的第一線治療方法。許多人對於眼藥水內的活性成分並不熟悉，亦未能分辨相關成分是否對眼睛有害。非處方的滋潤型眼藥水可能含有防腐劑苯扎氯銨（BAK）。防腐劑有助延長眼藥水的保質期限，防止細菌在眼藥水開封後滋生。BAK會對結膜和角膜細胞造成細胞毒性傷害，頻繁或長時間使用可以損害眼睛表面。BAK應用於不同類型的藥性眼藥水例如抗生素中，其毒性在短期使用反而有其可取之處。另外，標榜能夠改善眼紅症狀的滋潤型眼藥水一般含有化學成分如四氫唑啉，能夠令眼睛表面的血管收縮。頻繁或長時間使用此類眼藥水會令血管在停藥後反彈及擴張。整體對需要長期使用眼藥水的慢性乾眼症患者而言，使用不含防腐劑的人工淚液可能是更安全的選擇。
雖然不含防腐劑的人工淚液價格較高，不過相對而言，更令人關注的似乎是患者是否有跟從指示使用眼藥水。對於輕微至中度乾眼症患者而言，建議劑量為每日四至六次；嚴重患者則有機會每一至兩小時就需要使用一次。由此可以預視到大部分慢性乾眼症患者均未必有遵守眼藥水的使用指示。
接下來讓我們了解一下淚液，淚液可以分為三種類型：基礎性淚液、情感性淚液和反射性淚液。基礎性淚液持續在眼睛內擔當潤滑、滋養及保護角膜的角色，防止灰塵及碎屑進入眼睛；反射性淚液則會在眼睛需要沖走有害刺激物如煙霧或異物時形成。其中基礎性淚液正正是乾眼症患者所需的淚液類型。基礎性淚液由油脂、水液及黏液組成來維持淚膜穩定。最近有一項能夠緩解乾眼症的嶄新技術在香港推出。命名為iTEAR 的非侵入性設備有助改善自身淚液分泌，從而減低對眼藥水的依賴程度。iTEAR是一款外鼻神經刺激設備，透過非入侵性振動技術刺激外鼻神經，促進自身淚液分泌。此項刺激神經的嶄新技術能夠用於治療乾眼症，並已通過臨床驗證及美國食品和藥物管理局（FDA）認可。另一項嶄新技術是噴鼻劑Tyrvaya（伐尼克蘭溶液0.03毫克），然而此項產品尚未在香港上市。
iTEAR – 用於外鼻的神經刺激設備與及Tyrvaya – 用於鼻內的化學神經刺激藥物，有機會為未來的乾眼症治療帶來重大改變。對於慢性乾眼症患者而言，相對天然、安全以及無防腐劑的治療方式能夠從根源改善自身淚液分泌，可能會是更好的治療選擇。
Normally when we talk about dry eyes, we think about eyedrops. When you go to a pharmacy, there are seemingly endless choices of eyedrops. There are numerous brands, some with preservatives and some without, different viscosity eyedrops to eye gels, some contain vasoconstrictors to help “reduce redness”, and their costs can vary tremendously. Besides eyedrops, other dry eye treatments are available. For example, home remedies such as warm compresses, humidifiers, and treatments received at an ophthalmologist’s clinic like punctal plugs, meibomian gland expression and intense pulsed light (IPL).
However, eyedrops are by far the most commonly used first-line treatment for dry eyes because they do not require a prescription, and can be easily purchased over-the-counter (OTC). Many people do not know the active ingredients in their eyedrops or whether they may actually be harmful to the eye. The majority of OTC lubricant eyedrops use a preservative called benzalkonium chloride (BAK). A preservative is required to lengthen shelf life and to prevent bacteria from growing inside the bottle after it has been opened. BAK is well known to cause cytotoxic damage to conjunctival and corneal epithelial cells. Therefore, it can be harmful to the eye surface when used frequently or over a long period of time. BAK is also commonly used in many different types of medication eyedrops such as antibiotics, where its toxicity can actually be an advantage for short-term use. Lubricant eyedrops which claim to “reduce redness” usually contain chemicals such as tetrahydrozoline that constricts blood vessels on the eye surface. Frequent and long-term use of these eyedrops can cause rebound dilation of the blood vessels when the eyedrop is discontinued. Overall, it is understandable that for chronic dry eye patients, the use of preservative-free artificial tears may be the safer option as long-term use is expected.
Even if the more expensive cost of preservative-free artificial tears is not of concern, compliance may be another big issue. A four to six times per day dosing is usually recommended for mild to moderate dry eye patients. More severe patients may require every 1-2 hourly dosing. Therefore, poor compliance with eyedrops use can be expected in a large population of chronic dry eye patients.
Let us digress a bit to review some basic facts about tears. There are three types of tears we produce: basal, emotional and reflex tears. Basal tears are in your eyes all the time to lubricate, nourish and protect your cornea. It acts as a constant shield between the eye and the rest of the world, keeping dirt and debris away. Reflex tears are formed when your eyes need to wash away harmful irritants, such as smoke or foreign bodies. Basal tearing is the type of tear you want to improve for dry eye patients. Basal tears have a combination of oil, water, and mucus to help maintain a stable tear film. Recently, a new technology for relieving dry eyes was launched in Hong Kong. It is a non-invasive device that can improve our own natural tear production, thereby reducing our dependence on eyedrops use. This device called iTEAR, is an external nasal stimulator that utilises a non-invasive technology to stimulate the external nasal nerve to promote natural tear production. This novel pathway of neurostimulation for the treatment of dry eyes has been clinically proven and is also U.S. Food and Drug Administration (FDA) approved. A second form of this novel treatment is in the form of a nasal spray called Tyrvaya (Varenicline solution 0.03mg). This product, however, is currently unavailable in Hong Kong.
iTEAR (an extra-nasal mechanical neurostimulation device) and Tyrvaya (an intra-nasal chemical neurostimulation medication) may in the future lead to a paradigm shift in the treatment of dry eyes. This natural, safe, preservative-free modality may be a better choice for patients with chronic dry eyes to restore their ability to produce natural tears from the root.