乾眼症 8 大迷思
點人工淚液越點越乾？熱敷沒科學？

迷思 1 · 「人工淚液越點越乾、會依賴」

BAK 全名 Benzalkonium chloride，是多劑型瓶裝人工淚液最常用的防腐劑。TFOS DEWS II 報告明確指出：BAK 高頻次使用會破壞眼表的 lipid layer 與角膜上皮 tight junction，引發 epithelial toxicity，反而讓乾眼惡化。

真正的「依賴感」其實來自兩件事：(1) 患者本身的瞼板腺機能障礙（MGD)持續惡化，讓淚膜越來越不穩定，自然越點越要點;(2) 反覆使用含 BAK 滴劑造成的醫源性傷害。

解法很簡單：如果一天點 4 次以上，改用 preservative-free（無防腐劑）單支裝，或 ABAK / Comod 過濾瓶系統。這類產品設計就是讓你需要點幾次點幾次，不會累積毒性。

迷思 2 · 「眼睛狂流淚就一定不是乾眼」

蒸發型乾眼（Evaporative DED）約佔所有乾眼症的 85%,主因是瞼板腺機能障礙（MGD）讓淚膜油脂層不足，淚水蒸發太快。眼表面持續低度刺激會啟動三叉神經反射,讓副淚腺（Krause / Wolfring 腺）+ 主淚腺大量分泌「水樣淚」反流。

但這種「反射性淚水」品質很差 — 沒有油脂、沒有黏液素、沒有抗菌蛋白，只能短暫覆蓋眼表面，馬上又蒸發。所以患者會出現一個矛盾的情況：一邊狂流淚，一邊覺得乾、刺、糊。

診斷不能只靠「我會不會流淚」，要看：Schirmer test（基礎分泌量）、TBUT（淚膜破裂時間，正常 >10 秒）、瞼板腺 meibography（油脂腺萎縮程度）。三個一起看才能分清是水液型（aqueous-deficient）還是蒸發型，治療方向完全不同。

迷思 3 · 「乾眼症是老人病，年輕人不會」

TFOS DEWS II 流行病學報告指出，全球年輕族群的乾眼症盛行率正在快速上升。三大年輕化推手：

• 3C 螢幕使用 — 看螢幕時瞬目率從正常 15-20 次/分鐘掉到 5-7 次/分鐘,而且常常是「不完全眨眼」(incomplete blinking),導致瞼板腺長期推不出 meibum、開口阻塞。
• 軟式隱形眼鏡 — 使用者中有 50% 出現隱形眼鏡相關乾眼（contact lens-induced dry eye, CLIDE),每多戴一年發生率上升。
• 年輕女性自體免疫疾病 — Sjögren's syndrome、SLE、RA 經常以乾眼、口乾、關節痛作為早期表現。20-30 歲女性突發嚴重乾眼，有時是 Sjögren's 的首發症狀。

如果您 30 歲以下、長時間用螢幕、戴隱眼，還抱怨眼睛乾澀刺痛 — 不是錯覺，該看就看。

迷思 4 · 「葉黃素吃了就能治乾眼」

葉黃素（Lutein)+ 玉米黃素（Zeaxanthin）是黃斑部色素的主要組成。最強的證據來自 AREDS2 研究,針對中度年齡相關性黃斑部病變（AMD),補充劑可降低惡化風險，但這跟乾眼症完全是兩回事。

對乾眼症有理論基礎的營養補充是 Omega-3 多元不飽和脂肪酸（EPA / DHA) — 機轉是抑制 ocular surface 的 inflammatory cascade、改善 meibum 流動性。但 2018 年發表在 NEJM 的 DREAM trial(n=535）結果是：每天 3000 mg Omega-3 vs 橄欖油安慰劑，12 個月後乾眼症狀分數沒有統計顯著差異。

因此 AAO Preferred Practice Pattern 把 Omega-3 從 strong recommendation 降為 conditional recommendation — 意思是「想試可以試，但別把它當主治療」。葉黃素則完全不在乾眼指引內。

迷思 5 · 「點一陣子藥就會痊癒」

DEWS II 對乾眼症的定義是：「淚膜恆定性失調 + 慢性發炎」造成的多因子眼表面疾病。「慢性」是關鍵字 — 它不是急性感染可以「一個療程治癒」，而是要像高血壓、糖尿病一樣長期管理。

AAO 階梯式治療架構：

多數人停在 Step 1-2 就能控制良好。「停藥就復發」是常態，不是治療失敗，就像高血壓藥停了血壓會回升一樣。

迷思 6 · 「人工淚液都差不多，選便宜就好」

人工淚液依組成大致分四類：

但比成分更關鍵的是 防腐劑。台灣多劑型瓶裝幾乎都含 BAK，長期高頻次使用會累積角膜上皮毒性。

迷思 7 · 「熱敷沒效，只是心理作用」

瞼板腺（Meibomian gland）分泌的「meibum」在體溫（36°C）下是固體蠟狀,要熔化排出需要 40°C 以上。冷敷或常溫敷對 MGD 完全無效；這是物理事實，不是科學新發現。

有效熱敷的三條件：

1. 溫度 40-45°C — 過熱會燙傷，過低融不了 meibum。
2. 時間 10-15 分鐘 — 短於 5 分鐘無效，因為熱量還沒滲透到瞼板腺深處。
3. 加壓推按 — 熱敷完立刻做瞼板腺按摩（由眼皮根部往睫毛方向推），把熔化的 meibum 擠出腺體開口。

市售 USB 熱敷眼罩多在 38-42°C 邊緣，實測差異很大，要看認證。最穩定的還是新鮮溫毛巾（每 2 分鐘換一次保溫）、或是診所做IPL（脈衝光）、LipiFlow 熱壓系統。

迷思 8 · 「乾眼症不會傷眼睛，忍一忍就好」

輕度乾眼是討厭但沒事；中重度（尤其 Sjögren's、SLE、骨髓移植後 GVHD 族群）則真的會出事。臨床上常見的併發症：

• 絲狀角膜炎（Filamentary keratitis) — 黏液絲附著在角膜表面，每眨眼都拉扯，劇痛 + 異物感。
• 持續性角膜上皮缺損（Persistent epithelial defect, PED) — 反覆破皮無法癒合，變成復發性糜爛。
• 角膜潰瘍（Corneal ulcer) — 屏障破壞 + 細菌定植，需要強效抗生素。
• 角膜融解（Corneal melt) — 自體免疫乾眼最嚴重的併發症，可能穿孔致失明，屬於急症。

所以反覆出現「眼睛紅、刺痛、視力下降」絕不要拖。該做就做 Schirmer + TBUT + 角膜染色（fluorescein / lissamine green / rose bengal),該轉醫學中心就轉。

台灣健保給付規定（民國 115 年 4 月版）

乾眼症相關藥品的台灣健保現行給付規定：

實務小提醒：

• 健保門檻偏「客觀徵象」——若主觀症狀嚴重但 Schirmer / TBUT / 角膜染色不符合條件（即「症狀-徵象不一致」型，DREAM 研究有專文討論），常常拿不到健保給付，需自費。藥局開架式人工淚液選擇多、單支裝（無防腐劑）約 NT$ 200–400/盒。
• Lifitegrast 眼用製劑（如 Xiidra）：目前台灣健保未收載，全自費。
• 類固醇眼藥水（如 fluorometholone、loteprednol）：健保通常可開立，但短期使用、需眼科醫師監測眼壓與後囊下白內障風險，請勿長期自行使用。
• 健保規定隨時間更新，本文以民國 115 年 4 月版為準，最新版本以健保署公告為準。

* 來源：衛福部健保署《全民健康保險藥品給付規定》民國 115 年 4 月版，第 14 章「眼科用藥」14.5「人工淚液」、14.9.3「Cyclosporine 眼用製劑」、第 1.5.1 章「Pilocarpine hydrochloride 口服劑型」（修格蘭氏症診斷標準參 2002 年歐洲共識）。

在家可以做的 5 件事

做了以上 5 件事還是嚴重乾澀、起床時黏不開眼睛、看東西時好時壞 — 請至眼科專科醫師處接受完整評估，排除 Sjögren's 等系統性疾病。

主要參考文獻

1. Craig JP, et al. TFOS DEWS II Definition and Classification Report. Ocul Surf. 2017;15(3):276-283. doi:10.1016/j.jtos.2017.05.008
2. Wolffsohn JS, et al. TFOS DEWS II Diagnostic Methodology Report. Ocul Surf. 2017;15(3):539-574.
3. Jones L, et al. TFOS DEWS II Management and Therapy Report. Ocul Surf. 2017;15(3):575-628.
4. Akpek EK, et al. Dry Eye Syndrome Preferred Practice Pattern. American Academy of Ophthalmology. Ophthalmology. 2019;126(1):P286-P334.
5. Asbell PA, et al. n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease (DREAM Study). N Engl J Med. 2018;378(18):1681-1690.
6. Walsh K, Jones L. The use of preservatives in dry eye drops. Clin Ophthalmol. 2019;13:1409-1425.
7. Geerling G, et al. The international workshop on meibomian gland dysfunction: management and treatment. Invest Ophthalmol Vis Sci. 2011;52(4):2050-2064.

Myth 1 · "Artificial tears make your eyes drier; you'll become dependent on them"

BAK (benzalkonium chloride) is the most common preservative in multi-dose artificial-tear bottles. The TFOS DEWS II report clearly states that high-frequency BAK exposure disrupts the ocular-surface lipid layer and corneal epithelial tight junctions, causing epithelial toxicity and worsening dry eye over time.

The "dependency" feeling actually comes from two sources: (1) the patient's underlying meibomian gland dysfunction (MGD) progressively worsens, making the tear film increasingly unstable; (2) iatrogenic injury from chronic BAK use.

The fix is simple: if you use drops more than 4 times per day, switch to preservative-free single-dose vials, or ABAK / Comod filtering systems. These can be used as often as needed without accumulating toxicity.

Myth 2 · "Watery eyes can't be dry eye"

Evaporative DED accounts for about 85% of all dry eye cases. Meibomian gland dysfunction (MGD) leads to insufficient lipid in the tear film and faster evaporation. Persistent low-grade ocular-surface irritation activates a trigeminal reflex that triggers the accessory lacrimal glands (Krause / Wolfring) and main lacrimal gland to release watery tears.

But this reflex tear has poor quality — no lipid, no mucin, no antimicrobial proteins — and only briefly covers the surface before evaporating. So the patient experiences a paradox: watering and dryness/burning/blurriness at the same time.

Diagnosis cannot rest on "do you tear?" alone. Required tests: Schirmer (basal secretion), TBUT (tear break-up time, normal >10 s), meibography (gland atrophy). Together they distinguish aqueous-deficient from evaporative subtype — treatment differs entirely.

Myth 3 · "Dry eye is a senior disease; the young don't get it"

TFOS DEWS II epidemiology shows accelerating prevalence in young adults globally. Three drivers:

• Screen use — blink rate drops from a normal 15–20/min to 5–7/min, often with incomplete blinking, leading to chronic meibomian outflow obstruction.
• Soft contact lenses — up to 50% of users develop contact lens-induced dry eye (CLIDE), incidence rising with each year of wear.
• Autoimmune disease in young women — Sjögren's syndrome, SLE, and RA often present early as dry eye, dry mouth, joint pain. New-onset severe dry eye in a 20–30-year-old woman warrants Sjögren's workup.

If you're under 30, work long screen hours, wear contacts, and complain of burning/grittiness — it isn't your imagination. See an ophthalmologist.

Myth 4 · "Lutein cures dry eye"

Lutein and zeaxanthin are the principal carotenoids of the macular pigment. The strongest evidence comes from the AREDS2 study in moderate age-related macular degeneration (AMD) — supplementation reduces progression risk. But that has nothing to do with dry eye.

The supplement with theoretical basis for dry eye is omega-3 polyunsaturated fatty acids (EPA / DHA) — modulating the inflammatory cascade and improving meibum fluidity. But the 2018 NEJM DREAM trial (n=535) found no significant difference between 3000 mg/day omega-3 and olive oil placebo at 12 months.

Consequently the AAO Preferred Practice Pattern downgraded omega-3 from a strong to a conditional recommendation — try if you wish, but it's not primary therapy. Lutein doesn't appear in dry eye guidelines at all.

Myth 5 · "A short course of medication will cure it"

DEWS II defines dry eye as a multifactorial ocular-surface disease driven by "loss of tear-film homeostasis + chronic inflammation." Chronic is the key word — not an acute infection cured in one course; it requires long-term management like blood pressure or blood sugar.

The AAO stepladder framework:

Most patients control well at Steps 1–2. "Stopping the drops makes it come back" isn't treatment failure — it's the same as blood pressure rising once the antihypertensive is stopped.

Myth 6 · "All artificial tears are basically the same — pick the cheapest"

Artificial tears fall into four broad classes:

But the bigger lever is the preservative. Most multi-dose bottles in Taiwan contain BAK; high-frequency long-term use accumulates corneal epithelial toxicity.

Myth 7 · "Warm compresses don't work; it's just placebo"

Meibum (meibomian gland secretion) is solid wax at body temperature (36°C); melting and expressing it requires >40°C. Cold or room-temperature compresses are physically useless against MGD — this is physics, not new research.

Three conditions for an effective warm compress:

1. Temperature 40–45°C — too hot burns, too low fails to melt meibum.
2. Time 10–15 min — under 5 minutes, heat hasn't penetrated to the deep glands.
3. Pressure / massage — immediately after compress, roll-press from lid base toward the lash margin to extrude melted meibum.

Commercial USB warming masks often hover at 38–42°C with poor reliability. Most stable: fresh warm towels (replaced every 2 minutes), or in-clinic IPL (intense pulsed light) or LipiFlow thermal pulsation.

Myth 8 · "Dry eye doesn't damage eyes — just bear it"

Mild dry eye is annoying but harmless. Moderate-to-severe — especially in Sjögren's, SLE, post-bone-marrow transplant GVHD — can cause:

• Filamentary keratitis — mucin filaments adherent to cornea; each blink tugs them, severe pain and foreign-body sensation.
• Persistent epithelial defect (PED) — recurrent erosion that fails to heal.
• Corneal ulcer — barrier breakdown plus bacterial colonization; needs potent antibiotics.
• Corneal melt — the worst complication of autoimmune DED; can perforate and cause blindness — an emergency.

So recurrent redness, pain, or vision loss should never be ignored. Get Schirmer + TBUT + corneal staining (fluorescein / lissamine green / rose bengal) without delay; tertiary referral if needed.

5 things you can do at home

If symptoms persist despite all five — eyes stuck shut on waking, fluctuating vision — see an ophthalmologist for a full workup, including Sjögren's screening.

Key references

1. Craig JP, et al. TFOS DEWS II Definition and Classification Report. Ocul Surf. 2017;15(3):276-283.
2. Wolffsohn JS, et al. TFOS DEWS II Diagnostic Methodology Report. Ocul Surf. 2017;15(3):539-574.
3. Jones L, et al. TFOS DEWS II Management and Therapy Report. Ocul Surf. 2017;15(3):575-628.
4. Akpek EK, et al. Dry Eye Syndrome Preferred Practice Pattern. American Academy of Ophthalmology. Ophthalmology. 2019;126(1):P286-P334.
5. Asbell PA, et al. n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease (DREAM Study). N Engl J Med. 2018;378(18):1681-1690.
6. Walsh K, Jones L. The use of preservatives in dry eye drops. Clin Ophthalmol. 2019;13:1409-1425.
7. Geerling G, et al. The international workshop on meibomian gland dysfunction: management and treatment. Invest Ophthalmol Vis Sci. 2011;52(4):2050-2064.