Contact lenses are generally safe for vision correction, but they can occasionally lead to complications such as corneal scratches (abrasions) or ulcers (keratitis). These issues typically arise not from the lens itself, but from improper handling, poor hygiene, or wearing lenses for longer than recommended. The cornea is a highly sensitive and clear layer at the front of the eye that requires a constant supply of oxygen and moisture to remain healthy. When a contact lens interferes with this balance or introduces harmful bacteria, the risk of damage increases. Understanding the signs of these conditions and following strict safety protocols is essential for every contact lens wearer in the United Kingdom to protect their sight and maintain ocular health.
What We’ll Discuss in This Article
- The biological mechanisms that lead to corneal abrasions and ulcers.
- Common symptoms of a scratched cornea versus a corneal infection.
- The role of hygiene and “over-wearing” in increasing medical risks.
- How bacteria and parasites like Acanthamoeba cause rapid corneal damage.
- Practical steps for the immediate management of eye pain or redness.
- UK clinical guidance on when to seek urgent professional assistance.
Understanding Corneal Scratches (Abrasions)
A corneal abrasion is a physical scratch on the surface of the eye. In contact lens wearers, this often happens during the insertion or removal process, particularly if a fingernail accidentally grazes the eye. It can also occur if a small piece of grit, dust, or makeup becomes trapped underneath the lens. Because the lens is held against the eye by the eyelids, the trapped debris is repeatedly rubbed across the cornea every time the wearer blinks. A damaged or torn contact lens can also have a sharp edge that causes a similar mechanical scratch.
While a minor scratch often heals within 24 to 48 hours, it causes significant discomfort, redness, and a constant “gritty” sensation. The most dangerous aspect of a corneal scratch is that it breaks the eye’s natural protective barrier, the epithelium. This opening provides a gateway for bacteria to enter the deeper layers of the cornea. According to the NHS, any suspected scratch in a contact lens wearer should be treated with caution, as it significantly increases the vulnerability of the eye to more serious infections.
The Development of Corneal Ulcers (Keratitis)
A corneal ulcer, or microbial keratitis, is a much more serious condition than a simple scratch. It is an open sore on the cornea, usually caused by a bacterial, fungal, or parasitic infection. In the context of contact lens wear, ulcers often develop when bacteria are introduced to a compromised cornea via contaminated lenses, storage cases, or non-sterile water. Some bacteria, such as Pseudomonas, are particularly aggressive and can cause a deep ulcer that progresses significantly within just 24 hours.
If an ulcer is not treated promptly with intensive antibiotic or antimicrobial drops, it can lead to permanent scarring on the cornea. Because the cornea must remain perfectly clear for light to pass through, a scar can result in permanent blurred vision or even blindness. The National Institute for Health and Care Excellence (NICE) provides clinical pathways for the urgent management of these cases, emphasizing that any contact lens wearer with a painful, red eye must be assessed by a professional to rule out an active ulcer.
The Risks of Over-Wearing and Poor Hygiene
One of the leading causes of both abrasions and ulcers is the practice of over-wearing contact lenses. When a lens is worn for too many hours, or if an individual sleeps in lenses not designed for overnight use, the cornea is deprived of oxygen (hypoxia). This causes the surface cells to become “loose” and more easily damaged. Furthermore, sleeping in lenses creates a stagnant environment where trapped bacteria can multiply without being washed away by the natural flushing action of tears and blinking.
Hygiene lapses, such as rinsing lenses in tap water or failing to wash hands before handling lenses, are the primary ways that dangerous pathogens reach the eye. Water-borne parasites like Acanthamoeba are especially hazardous; they can cause a rare but devastating ulcer that is notoriously difficult to treat. Clinical guidance from the College of Optometrists highlights that strict adherence to the “no water” rule and the recommended replacement schedule is the single most effective way to prevent contact lens-related ulcers.
Symptoms: Abrasion vs. Ulcer
| Feature | Corneal Abrasion (Scratch) | Corneal Ulcer (Infection) |
| Pain Level | Sharp, immediate, “gritty” feeling | Severe, throbbing, or deep aching pain |
| Redness | Generalised redness of the eye | Often intense redness, especially near the cornea |
| Vision | Usually normal or slightly blurred | Often significantly blurred or foggy |
| Discharge | Watery eyes | Pus-like, thick, or discoloured discharge |
| Visible Sign | Difficult to see without specialist dye | May appear as a tiny white or grey spot on the cornea |
| Light Sensitivity | Moderate | Extreme (difficult to open the eye in light) |
Immediate Management and “Red Flags”
If you suspect you have a corneal scratch or if your eye becomes painful while wearing a contact lens, the first step is always to remove the lens immediately. Do not attempt to reinsert it or try a new lens. If the pain is caused by a minor scratch, the eye will often feel slightly better once the lens is removed, although the sensation of something being “in the eye” may persist. You should avoid rubbing your eye, as this can worsen a scratch or push bacteria deeper into an ulcer.
There are certain “red flag” symptoms that indicate you must see an eye specialist or attend an eye casualty department urgently. These include a visible white or grey spot on the clear part of your eye, severe pain that prevents sleep, a sudden drop in vision, or a thick, yellow discharge. In the UK, early intervention is the most successful way to treat a corneal ulcer. Most infections can be managed effectively if antibiotic treatment is started before the infection reaches the central part of the cornea.
Prevention and Safe Lens Habits
Preventing corneal damage is largely a matter of following the hygiene and wearing rules provided during your contact lens fitting. This includes always washing and drying your hands thoroughly, using fresh sterile solution every day, and replacing your lens case at least every three months. You should also ensure your lenses are in good condition; never wear a lens that is chipped, torn, or feels uncomfortable from the moment it is inserted.
Regular contact lens check-ups are also vital. During these appointments, an optometrist uses a slit-lamp microscope and a special yellow dye (fluorescein) to look for microscopic scratches or signs of oxygen stress that you might not be able to feel yet. These routine checks allow for adjustments in lens material or wearing schedules before a serious problem develops. By being proactive and respecting the limits of your eyes, you can enjoy the benefits of contact lenses while minimizing the risk of sight-threatening complications.
Conclusion
Contact lenses can cause corneal scratches through mechanical irritation or ulcers through bacterial infection, particularly if hygiene and wearing schedules are neglected. A scratch is often a precursor to an ulcer, as it breaks the eye’s natural protective layer. While minor abrasions may heal quickly, a corneal ulcer is a medical emergency that can lead to permanent vision loss if not treated urgently. If you experience severe, sudden, or worsening symptoms, call 999 immediately.
Can a contact lens scratch be permanent?
Most superficial scratches heal completely within a few days, but a deep scratch that becomes infected can lead to a permanent scar.
Why does my eye feel like something is in it after I take my lens out?
This is a common symptom of a corneal abrasion; the “foreign body” sensation is caused by the eyelid rubbing over the exposed sensitive nerves of the scratch.
Can I use tap water to rinse a scratched eye?
No, you should only use sterile saline or cooled boiled water; tap water contains parasites that can turn a simple scratch into a severe ulcer.
How do I know if the white spot on my eye is an ulcer?
Any new white or grey spot on the clear part of the eye in a contact lens wearer should be treated as a potential ulcer until proven otherwise by a professional.
Will my vision go back to normal after a corneal ulcer?
This depends on the location and severity; if the ulcer is caught early and does not leave a central scar, vision usually returns to normal.
Is it safe to wear makeup with a scratched cornea?
No, you should avoid all eye makeup until the scratch has completely healed to prevent irritation and the introduction of bacteria.
Can I wear a “bandage” contact lens for a scratch?
In some cases, an optometrist or doctor may fit a special therapeutic lens to protect the eye while it heals, but you must never use your own lens for this purpose.
Authority Snapshot (E-E-A-T Block)
This article provides a clinical overview of the risks, symptoms, and management of corneal scratches and ulcers related to contact lens wear in the UK. It was reviewed by Dr. Rebecca Fernandez, a UK-trained physician with experience in emergency medicine and internal medicine, to ensure accuracy and alignment with NHS and NICE safety guidance. The information is intended to support patient safety through education on infection prevention and urgent ocular care.
