Optician India

Puja Sarkar, Anterior Segment Department, Dr. Shroff’s Charity Eye Hospital, New Delhi

In the world of vision correction, contact lenses offer freedom- no foggy glasses, no slipping frames, just clear, natural vision. But the convenience comes responsibility. The cornea the transparent front part of eye, is where the contact lens rest every day. It’s a delicate, living tissue – and if it’s not treated with care, things can go wrong.

Understanding the Cornea : More Than Just a Window

The cornea is a clear, dome-shaped surface that covers the front of the eye. It plays a vital role in focusing incoming light onto the retina, contributing significantly to our ability to see clearly. Unlike other tissues, the cornea lacks blood vessels and relies on oxygen from the air and nutrients from tears. This unique structure makes it particularly susceptible to damage and infection, especially when compromised by improper contact lens use.? It compose of five layers – each with a specific role in maintaining transparency, protecting the eye and ensuring proper refraction of light.

Here’s why the cornea matters:

• Transparency: It allows light to enter the eye
• Refraction: It bends (refracts) incoming light to focus it on the retina.
• Barrier Function: It protects against dust, pathogens and injury.
• Oxygen Dependency: Since it has no blood supply, the cornea receives, oxygen directly from the atmosphere and tears.

How Contact Lenses Interact with the Cornea

Contact lenses rest directly on the cornea, and while they are designed to be safe, certain practices can pose risks:

1. Oxygen Deprivation (Corneal Hypoxia)

When a contact lens covers the cornea, it partially blocks oxygen from reaching the corneal cells. Modern lenses (especially silicone hydrogel lenses) are designed to be more breathable, but hypoxia can still occur – especially for extended wear and improper fitting.

Symptoms of hypoxia include:

• Redness
• Blurred vision
• Light sensitivity
• Corneal Edema

2. Mechanical Stress and Abrasions

Contact lens can cause abrasion to the corneal epithelium, if it is worn for too long, not fitted properly, or handled roughly. This can disrupt the protective surface, making the eye more susceptible to infection.

3. Dryness and Tear Film Disruption

Contact lens can reduce tear exchange and disrupt the tear film, leading to symptoms of dry eye. This is especially common in people who wear lenses for many hours a day, work in air- conditional environments, or spend long hours on screens

Symptoms:

• Foreign body sensation
• Burning or stinging
• Intermittent blurry vision

4. Risk of Infections

This is one of the most serious complications related to contact lens wear. Poor hygiene, extended wear, or sleeping in contact lenses can lead to serious infections like microbial keratitis—a corneal infection that can cause pain, redness, and vision loss.

Risk factors include:

•  Overnight lens wear
•  Not replacing lenses or cases as directed
•  Using tap water or homemade saline
•  Wearing lenses while swimming or showering

5. Allergic reaction and deposits

Protein and lipid deposits from tears can accumulate on lenses, especially with extended use These deposits can trigger allergic reactions and cause discomfort.

Some may develop Giant papillary conjunctivitis (GPC), a condition where the inner eyelid becomes inflamed and bumpy due to chroniuc irritation from klens deposits or overwear.

Best Practices for Healthy Cornea and Safe Contact Lens Use

A few simple habits can make all the difference in protecting cornea:

Proper Hygiene

•  Always wash and dry hands before touching lenses .
•  Clean and disinfect lenses as recommended
•  Never use tap water, saliva or expired solutions.

Follow Wear Schedule

•  Stick to the prescribed duration – daily lenses should be discarded after one use.
•  Never sleep in lenses unless approved by eye care provider.

Keep lenses away from water

•  Remove lenses before swimming or showering
•  Water (including distilled or filtered) may contain microorganisms like Acanthamoeba that can cause devastating corneal infections.

Replace Your Lens Care Regularly

•  Redness, discomfort, or blurred vision are warning signs.
•  Remove lenses and consult eye care practitioner if symptoms persist.

Schedule Regular Eye Exams

•  Annual check-up help ensure lenses fit well and cornea remains healthy.
•  Eye care practitioner can detect early signs of complications.

References

1. Chalmers, R. L., et al. (2012). "Impact of contemporary contact lenses on ocular surface." Contact Lens & Anterior Eye, 35(4), 148–154

2. Craig, J. P., et al. (2017). "TFOS DEWS II Report." The Ocular Surface, 15(3), 276–403. (Very important for dry eye and contact lens interaction.)

3. Sindt, C. W., & Longmuir, R. A. (2007). "Scleral lenses: A literature review." Eye & Contact Lens, 33(6), 234–238.