A thin cornea refers to a condition where the cornea—the clear, dome-shaped front layer of the eye—has a thickness lower than normal, which can affect vision and overall eye health.
This condition may result from various causes such as natural aging, frequent eye rubbing, genetic disorders, or side effects from eye surgeries like LASIK. Common symptoms include blurry vision, frequent changes in prescription, distorted images, and unusually high astigmatism.
Understanding the Cornea
The cornea is the transparent, curved layer covering the front part of the eye. It helps focus light into the eye for clear vision and serves as a protective barrier against dust and germs. Normally, corneal thickness ranges between 520–550 microns, but it may thin with age.
What Is a Thin Cornea?
A thin cornea is typically defined as a corneal thickness of less than 500 microns (0.5 mm). It is not necessarily a disease and often requires no treatment. However, thin corneas can affect certain diagnoses—such as glaucoma—since intraocular pressure readings may appear lower than actual values.
Corneal thickness also plays an important role in refractive surgery decisions. For example, patients with thin corneas and high refractive errors (nearsightedness or astigmatism) may not be ideal candidates for LASIK, as the remaining corneal tissue after surgery might be too thin. This could increase the risk of complications like keratoconus or corneal ectasia.
In such cases, ophthalmologists may recommend alternative procedures such as PRK, ICL, FemtoLASIK, ReLEx SMILE Pro, or NanoLASIK, which preserve more corneal tissue. Therefore, detailed corneal thickness assessment is essential before undergoing LASIK to ensure safe and effective outcomes.
Does Wearing Contact Lenses Cause Thinning of the Cornea?
Generally, wearing contact lenses correctly does not thin the cornea. However, prolonged use without proper cleaning or rest may lead to oxygen deprivation or corneal infections, which can gradually weaken or thin corneal tissue.
Causes of Thin Cornea
There are several factors that can lead to corneal thinning:
1. Genetic Conditions
Keratoconus: The most common cause, where the cornea gradually thins and bulges outward into a cone shape, leading to irregular astigmatism and blurred vision. It usually appears during the teenage years to early adulthood.
Corneal Dystrophies: Such as Pellucid Marginal Degeneration (PMD), where thinning occurs in the lower peripheral cornea.
2. Eye Surgery or Injury
Procedures like LASIK or PRK can thin the cornea, especially if excessive corneal tissue is removed. Repeated eye injuries or untreated infections (e.g., corneal ulcers, keratitis) can also cause thinning due to tissue damage.
3. Systemic Diseases and Medication
Autoimmune diseases such as Rheumatoid Arthritis or SLE can cause chronic inflammation, leading to corneal thinning.Long-term use of steroid eye drops may also weaken corneal tissue over time.
Symptoms of Thin Cornea
Corneal thinning often progresses slowly and may not show early signs. Key symptoms include:
Blurry or distorted vision
Frequent changes in prescription
High or irregular astigmatism
Difficulty focusing or double vision
Diagnosis
Thin cornea is often detected during pre-LASIK evaluations.Eye doctors use devices like:
Keratometer: Measures corneal curvature and astigmatism.
Corneal Topography: Creates a detailed map of corneal thickness and shape.
Tomographic Biomechanical Index (TBI): Evaluates corneal strength and risk of ectasia.
While early symptoms can hint at the condition, only a comprehensive eye exam by an ophthalmologist can confirm it.
Summary
Thin cornea is a silent condition that can significantly impact vision if left untreated. Early detection—especially before refractive surgery—is crucial.At Bangkok Eye Hospital, advanced diagnostic tools and experienced specialists ensure accurate corneal thickness evaluation and personalized treatment planning to maintain long-term eye health.
FAQ: Frequently Asked Questions About Thin Cornea
1. Can corneal thickness be increased?No, corneal thickness cannot naturally increase as it is determined by the cornea’s internal structure.
2. What happens if thin cornea is left untreated?It may lead to worsening blurred vision, irregular astigmatism, or even corneal ectasia. In severe cases, acute hydrops or corneal perforation may occur, leading to permanent vision loss if untreated.
3. Can thin cornea be prevented?Yes — by avoiding vigorous eye rubbing, maintaining good eye hygiene, limiting contact lens wear time, and having regular eye checkups, especially if there is a family history of corneal diseases.
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