Many people experience red eyes, dry eyes, tearing, or a foreign body sensation and assume it's just eye strain — they tolerate it or use random eye drops. But these seemingly mild symptoms could indicate a corneal problem. The cornea has no blood vessels but is densely packed with nerves. Once inflamed, it heals very poorly, and delays can lead to ulcers, permanent vision loss, and even blindness.

What is keratitis?

The transparent, avascular, nerve-rich film in front of the "black part" of the eye is the cornea — the eye's "light window." When this window becomes inflamed due to infection, trauma, or immune issues, it's keratitis.

Critical warning: Because the cornea lacks blood vessels, it heals much slower than skin wounds. Inflammation leaves scars that permanently affect vision.

Daily habits that damage your cornea

1. Frequent eye rubbing
The corneal epithelium is a very thin protective layer. When intact, it blocks most pathogens. But even tiny breaks allow bacteria and fungi to invade the avascular cornea and cause severe inflammation. Rubbing with fingers introduces bacteria, fungi, and mites, physically abrading the epithelium and inoculating pathogens into any wound. Inflammation from adjacent tissues (conjunctivitis, iritis) can also spread to the cornea.

2. Improper contact lens use
Sleeping in contacts, swimming, overwearing, not replacing solution, or using non-sterile lenses are high-risk. Sharing eye drops or using unclean water (e.g., poorly maintained pools) is also dangerous. These cause corneal hypoxia, epithelial damage, tear contamination, and infections like bacterial or Acanthamoeba keratitis — the latter is extremely hard to treat and can cause blindness.

3. Overusing eye drops
Many believe “more drops = faster healing” — a major misconception. Key dangers:
Long-term heavy use of steroid drops suppresses epithelial cell division, weakens the barrier, and delays wound healing, inviting infection.
Overusing antibiotic drops disrupts the normal ocular flora, promoting resistant bacteria and fungi, leading to refractory infections.
Frequent use of preserved drops — preservatives directly damage the corneal epithelium, causing chronic ocular surface disease, dry eye, and keratitis.
Abuse can lead to persistent epithelial defects, recurrent infections, drug-induced keratitis, and even corneal thinning and perforation, threatening vision.

4. Unhealthy lifestyle: 熬夜 & alcohol
Chronic sleep deprivation, alcohol abuse, fatigue, immunosuppressants, or diseases like diabetes weaken the cornea's defenses. Sleep loss reduces immune cell activity, tear secretion, and tear film stability, drying and damaging the cornea, increasing infection risk. Alcohol dilates ocular vessels, worsens congestion, and impairs liver metabolism, reducing overall immunity and corneal repair capacity.

Four danger signs — seek medical care if any appear

1. Foreign body sensation, tearing, pain not relieved by rest
Typical eye strain improves with rest, warm compresses, or artificial tears. If these fail and symptoms worsen with pain and tearing, the corneal epithelium may be damaged or inflamed — nerve irritation requires immediate care.

2. Severe redness, dense blood vessels, increased discharge
Redness that doesn't improve with rest or ordinary drops, plus discharge, suggests acute bacterial or viral keratitis with spreading inflammation. Delay can lead to abscess or perforation.

3. Continuous, uncontrollable tearing
Microbial infection can damage corneal nerves, causing uncontrollable tearing. This indicates severe corneal damage; delays may cause permanent nerve damage, leading to sensitivity, dryness, and vision decline.

4. Eyelid swelling and difficulty opening the eye
Swollen eyelids, photophobia, and severe tearing are high-risk signs of corneal ulceration. Avoid self-medication or washing with water, as this can worsen infection, leading to perforation and endophthalmitis — blindness.

Treatment: three steps

Core principles: control infection, reduce inflammation, promote healing, minimize scarring and vision loss.

Step 1: General care
Mild cases use anti-inflammatory drops and artificial tears under medical guidance. Avoid overuse, take regular breaks, wear sunglasses outdoors to avoid light, pollen, and dust.

Step 2: Medications (different causes require different drugs — never self-prescribe)
Bacterial keratitis: levofloxacin, tobramycin drops.
Viral keratitis: acyclovir, ganciclovir gel.
Fungal keratitis: fluconazole, natamycin drops.
Severe cases may need oral antibiotics/antivirals/antifungals as directed by an ophthalmologist.

Step 3: Surgery
If medical therapy fails and ulcers or perforation develop, surgery — possibly corneal transplantation — is needed to preserve vision.

Critical reminder: Severe keratitis can truly cause blindness

The cornea is the only pathway for light to enter the eye. Severe inflammation, ulceration, or perforation turns it into an opaque white scar, blocking light.
Fungal, bacterial, and any delayed keratitis have high blindness rates and are a leading cause of blindness in China.

Eyes are delicate — don't ignore warning signs.
If you experience any suspicious symptoms, see an ophthalmologist immediately.
Protect your vision by taking every eye discomfort seriously.