bubble_chart Overview

Corneal abrasion: When external objects, especially those with rough surfaces, come into contact with or scrape the corneal surface, they can cause varying degrees of abrasion, such as corneal epithelial defects or detachment.

bubble_chart Clinical Manifestations

Due to the exposure of sensory nerve endings, the patient suddenly experiences obvious pain, tearing, eyelid spasms, and other irritative symptoms, with increased pain during blinking or eye movement. Even without foreign body retention, the patient still feels a distinct foreign body sensation.

bubble_chart Auxiliary Examination

By using oblique illumination with focused light (such as a flashlight source), defects in the corneal epithelium can be detected. At the same time, attention should be paid to identifying any foreign bodies on the cornea or conjunctiva. Particularly, the aforementioned conjunctival foreign bodies not only exhibit symptoms similar to corneal abrasions but are also often the cause of such abrasions. If epithelial defects are not detected with oblique illumination, fluorescein staining can be employed. The method involves instilling one drop of a 20% sterile sodium fluorescein solution into the conjunctival sac, instructing the patient to close their eyes for five minutes. After a brief pause, the patient's tears will wash away the remaining dye in the conjunctival sac (if excess dye remains, it can be rinsed away with saline). At this point, the corneal epithelial defects will appear green and become easily visible. Additionally, since fluorescein aqueous solution serves as an excellent culture medium for Pseudomonas aeruginosa and is prone to contamination by this bacterium, leading to severe infections in corneal wounds, fluorescein paper staining has become more commonly used in recent years. This involves applying a sterile fluorescein paper strip moistened with a drop of sterile saline to the palpebral conjunctiva. Alternatively, if fluorescein is not available, small or subtle abrasions can be detected using the projection method. By directing a well-focused light source onto the cornea, a shadow cast by the epithelial defect can be observed on the surface of the iris. Changing the angle of illumination will cause the shadow to move correspondingly in the opposite direction. If the patient is examined in a hospital equipped with ophthalmic facilities, slit-lamp microscopy naturally provides a more convenient method of examination.

bubble_chart Treatment Measures

Simple superficial abrasions generally respond well to treatment. If only the corneal epithelium is damaged or the epithelial layer is detached from Bowman's membrane, most cases can heal within 12 hours, while larger areas may take longer. However, improper handling or infection can not only prolong the course but also leave varying degrees of corneal opacity. The treatment methods are as follows:

1. Clean the conjunctival sac. If there are foreign debris, dust, or dirt in the conjunctival sac, sterile saline or a dilute solution of mercuric oxide or mercuric chloride should be used for irrigation and removal during the initial treatment.

2. Apply 0.5% or 1% gentamicin solution or 0.25%–0.5% chloramphenicol solution to the eye several times daily. If necessary, a subconjunctival injection of 10,000–20,000 units of gentamicin may also be administered.

3. Apply a broad-spectrum antibiotic ointment, such as 0.5% tetracycline or chlortetracycline ointment.

4. For larger abrasions with severe irritation, a weak mydriatic, such as 2% homatropine or cyclopentolate (Cyclogyl), can be used to alleviate symptoms and reduce the impact of secondary iridocyclitis.

5. Bandage the injured eye. After applying the ointment, cover it with sterile gauze and a pressure eye patch or pressure bandage. This should exert slight pressure to immobilize the eyelid, preventing it from moving with the other eyelid, rather than applying strong pressure to the eyeball. This reduces eyelid friction on the cornea, aiding corneal epithelial repair. The pressure bandage should remain in place until 24 hours after symptoms subside, only being removed temporarily for medication instillation. Generally, only the injured eye needs bandaging, but if the abrasion is extensive or slow to heal, both eyes may be bandaged.

6. Avoid using corticosteroid eye drops, frequent topical anesthetics, or repeated irrigation with antiseptics, as these may delay corneal epithelial regeneration.

7. Instruct the patient not to rub their eyes, blink forcefully, or wipe their eyes or tears with items like handkerchiefs.

8. All eye drops, including fluorescein solution or strips, conjunctival sac irrigation solutions, dressings, and instruments, must be strictly sterile.

9. If pain worsens or suddenly intensifies after initial relief, immediate examination is necessary. If infection is detected, aggressive control measures should be taken.

10. Sometimes, after the epithelium of a superficial corneal abrasion heals, the affected eye may suddenly experience pain, tearing, and photophobia—similar to the initial abrasion symptoms—weeks or months later, often upon waking in the morning. These symptoms usually subside within 1–2 days but may recur at intervals ranging from days to months. Examination may reveal recurrent epithelial detachment at the original abrasion site, with fluorescein staining of the defect. This is termed recurrent corneal erosion and may involve fine filamentous material adhering to the cornea, representing detached corneal epithelium or edematous superficial tissue. This condition often follows sharp corneal abrasions, possibly due to damage to the epithelial basement membrane, making it difficult for new epithelial cells to adhere firmly. Treatment primarily involves topical antibiotics to prevent infection and pressure bandaging, which can be quite effective. To prevent recurrence, applying ointment to the conjunctival sac before bedtime for several weeks may help. Soft contact lenses sometimes yield good results. Oral vitamin C (200mg four times daily) may also be beneficial. If infection occurs, treat as ulcerative keratitis or carefully apply iodine tincture to the infected area. If recurrent episodes persist despite various treatments, lamellar corneal transplantation may be considered.

2. Incised wounds of the cornea: Penetrating injuries of the cornea will be discussed in the section on penetrating eye injuries. Non-penetrating incised wounds of the cornea are relatively rare, and their symptoms are similar to those of corneal abrasions. The difference is that the injury is deeper, the healing time is longer, and after healing, scar-like corneal opacities are always left behind, often altering the original curvature of the corneal surface and affecting vision.

Treatment: In addition to cleaning the wound to remove debris and applying topical antibiotics to prevent infection, pressure bandaging and analgesics should be administered to alleviate the patient's pain. If the laceration is large, deep, and the wound edges are significantly gaping or poorly aligned, even if it does not penetrate the full thickness of the cornea, proper suturing should be considered. When suturing, fine needles and sutures must be used, preferably with an 8-0 monofilament nylon suture on a non-injury needle. The wound edges should be carefully aligned, and the sutures should be tied with appropriate tension—neither too loose nor too tight.

3. Corneal foreign bodies: Small foreign particles that remain on the surface of the cornea or become embedded in it are called corneal foreign bodies. The most common types include metal shavings from machine tools, small fragments from hammering, metal or gunpowder particles from explosions, coal dust, stone chips, airborne dust particles, grain husks, tiny thorns, etc. Among factory workers, iron shavings are the most frequent corneal foreign bodies. Most corneal foreign bodies remain in the superficial layers or on the surface of the cornea, but some may penetrate deeper. The number of foreign bodies can vary, ranging from one to several or even numerous.

Because the superficial layer of the cornea is rich in sensory nerve endings, it is highly sensitive to pain and touch. Therefore, corneal foreign bodies immediately cause noticeable irritative symptoms, such as a foreign body sensation, stabbing pain, tearing, conjunctival congestion, and eyelid spasms. The irritative symptoms of superficial foreign bodies are often more pronounced than those of deeper ones.

Findings on examination: Some corneal foreign bodies are easily visible and can be located using oblique illumination with a focal light. Others are harder to detect and require examination with a slit lamp, especially small, transparent foreign bodies, which must be carefully searched for. If necessary, fluorescein dye can be instilled to stain the surrounding cornea, making the foreign body easier to identify. During the examination, the depth of the foreign body should be noted, as deeper ones may partially enter the anterior chamber. Some corneal foreign bodies, particularly those caused by explosive injuries, may lead to traumatic corneal endothelial edema within 24–48 hours after injury, though this usually resolves within a few days.

Iron-containing foreign bodies often cause corneal infiltration, and after 1–2 days, a brown rust ring may form around them. Hot foreign bodies can burn the surrounding corneal tissue or create a carbon ring. If the foreign body causes infection, it may lead to a corneal ulcer.

Treatment: Once a corneal foreign body is detected during examination, it should be removed as soon as possible. The methods are as follows:

(1) Foreign bodies adhering to the corneal surface can be removed by irrigation. Using an eye wash bottle or irrigator, direct the water flow toward the bulbar conjunctiva near the foreign body, and the foreign body may be washed away. This method causes the least corneal injury.

(2) If the foreign body is on the corneal surface but cannot be removed by irrigation, instill 1–2 drops of a topical anesthetic, such as 1% dicaine solution, and gently wipe the foreign body away with a cotton swab moistened with saline.

(3) For foreign bodies embedded in the superficial layer of the cornea, if one end is exposed on the surface, the above method can also be attempted—using a moist cotton swab to wipe it away.

(4) If the foreign body is not exposed on the corneal surface or is firmly embedded and cannot be removed by the above methods, it can be extracted under topical anesthesia using a foreign body spud or a fine injection needle. When removing the foreign body, the needle tip should be directed toward the top of the head to prevent the patient from dodging or suddenly closing their eyelids, which could cause the eyeball to rotate upward and the needle to penetrate too deeply.

5. For deeply embedded foreign bodies, if they are magnetic, the superficial corneal membrane can be left uncut, and the foreign body can be directly reached and extracted using an electromagnet or permanent magnet. If the foreign body is non-magnetic or cannot be extracted with a magnet, a small corneal flap must first be cut, followed by interlayer separation. This flap is then lifted to expose the foreign body, which is carefully removed. Since the corneal flap is small, it may not require suturing. After repositioning the flap, the affected eye should be pressure-bandaged, with both eyes bandaged for 24 to 48 hours. Alternatively, a non-injury corneal needle and 10-0 suture can be used to suture the corneal flap. The handling of deep corneal foreign bodies must be extremely cautious; otherwise, during removal, the foreign body may be pushed deeper, potentially penetrating the cornea and falling into the anterior chamber. Alternatively, due to the outflow of aqueous humor, the anterior chamber may become shallow or disappear, risking injury to the iris or lens by the foreign body or instruments.

(6) If one end of the foreign body has already entered the anterior chamber, first constrict the pupil, then make an incision at the corneal limbus. Insert an iris repositor into the anterior chamber to support the foreign body from behind the cornea, and then remove it from the outside of the cornea. Alternatively, as described above, create a corneal flap and remove the foreign body from beneath the flap. Another method is to intentionally allow the foreign body to fall into the anterior chamber onto the surface of the iris after constricting the pupil, and then extract it as an anterior chamber foreign body.

(7) If there are numerous fragments or dust-like foreign bodies, remove the larger particles that are exposed on the surface. As the remaining foreign bodies gradually migrate forward to the surface, continue to remove them as they become exposed. If there are an extremely large number of fragments and severe irritation symptoms, perform a lamellar corneal transplant or epithelial scraping to remove the superficial foreign bodies together.

(8) The removal of foreign bodies must be performed under good illumination. For smaller foreign bodies, use binocular magnifying glasses during the procedure. For extremely small foreign bodies, it is best to operate under a slit lamp or surgical microscope. Deep foreign bodies, especially those requiring a corneal flap, should be removed under a surgical microscope with slit illumination.

(9) The rust ring can be scraped away immediately after removing the foreign body using a foreign body spud. If scraped a few days later, it is easier to remove completely. A chemical method for removing the rust ring is the local application of the chelating agent deferoxamine, using a 5%~10% solution or eye ointment, applied 4–6 times daily. This method can be used if the rust ring is not completely scraped off.

The carbon ring is easier to remove. Sometimes, a fine needle can be used to remove it intact in one attempt, or it can be scraped off with a foreign body spud.

(10) Precautions: The removal of foreign bodies must be performed with extreme precision to minimize corneal injury. Strict aseptic requirements must be followed. All instruments and medications, including fluorescein, tetracaine, saline, antibiotic ointments, or eye drops, must remain sterile. Regularly stocked medications should be replaced periodically to avoid infections, especially Pseudomonas aeruginosa infections, which require particular attention.

(11) Postoperative care: After removing the foreign body, apply antibiotic ointment and cover the eye with sterile gauze under pressure. Change the dressing daily until healing is complete. Generally, after removing the foreign body, the wound is very small, and the corneal epithelium can heal within 24 hours. Larger and deeper wounds take longer to heal. If infection occurs, treat it as a corneal ulcer.

(12) For superficial corneal foreign bodies, removal usually does not leave significant corneal opacity, though some may develop corneal leukoma. For deeper foreign bodies, even if removed promptly, some degree of corneal opacity often remains. If this opacity is located in the pupillary area, it can severely impair vision. Even if not in the central cornea, scar contraction may cause corneal refractive errors, such as astigmatism, which can also lead to reduced vision.