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ICL Surgery for Keratoconus

What is Keratoconus?

Keratoconus is a disease that causes the cornea to gradually thin. This condition leads to irregular corneal shape, resulting in significant myopia and irregular astigmatism. Depending on the progression speed, it may become uncorrectable by glasses or contact lenses, potentially requiring a corneal transplant.

While the exact cause is unknown, it is considered a congenital, progressive disease. Factors like eye rubbing due to atopy or allergies (causing corneal abrasions) are known to exacerbate the condition, though it can also develop without these factors.

In most cases, keratoconus goes undetected in the early stages due to a lack of subjective symptoms, and it is usually identified accidentally during pre-refractive surgery exams involving detailed corneal shape analysis. Surprisingly, it is found more frequently than expected, affecting approximately 1 in 1,000 people, making it not a rare condition.

The symptoms and treatment of keratoconus vary depending on the disease's progression. Not everyone with keratoconus experiences severe vision deterioration, and in many cases, good vision can be achieved with glasses, soft, or hard contact lenses. However, corrective surgeries involving laser corneal ablation are absolutely contraindicated, as they may cause rapid disease progression.

Keratoconus typically develops in adolescence, progresses during the 20s and 30s, and is less likely to progress after the age of 40. However, due to individual differences, regular check-ups are necessary to monitor the progression rate.

For individuals with mild keratoconus and stable corrective vision, combining keratoconus treatment with ICL surgery can significantly reduce myopia and astigmatism.

Flow of Keratoconus Treatment and
ICL Surgery

For keratoconus around the age of 20, due to the risk of progression, it is recommended to first undergo corneal collagen cross-linking to slow progression, observe the advancement of keratoconus and myopia, and then proceed with ICL surgery.

Severity of Keratoconus

Mild
(only minor astigmatism, not detectable in routine ophthalmologic exams)

- Good corrective vision can be achieved with glasses or contact lenses.

- Keratoconus can be diagnosed via corneal topography.

Moderate

- Vision correction can no longer be achieved with glasses or soft contact lenses. Hard contact lenses are therefore required for correction.

- Symptoms indicative of keratoconus may be observed in general ophthalmologic exams.

Severe

- Astigmatism increases, and corrective vision cannot be achieved with standard glasses or soft contact lenses.

- Although corrective vision may improve slightly with hard contact lenses, they are difficult to wear as they can easily dislodge.

- Custom hard contact lenses specifically for keratoconus are typically used for vision correction.

- Discomfort and pain from wearing hard contact lenses can be mitigated by layering them over daily disposable soft contact lenses.

Keratoconus Treatment

Corneal Cross-Linking (CXL)

1. The primary purpose of corneal cross-linking is to inhibit the progression of keratoconus, so it is performed for those with keratoconus or at high risk for the condition.

2. Recently, it has been suggested that early treatment is needed to prevent the progression of keratoconus.

3. Corneal cross-linking not only helps halt the progression of keratoconus but can also reduce myopia and astigmatism to some extent.

4. The downside of this procedure is that it causes significant pain for 2–3 days post-surgery, and it takes more than a week for vision to improve.

5. Individuals with atopy or allergic tendencies who frequently rub their eyes should be cautious, as keratoconus may progress even after corneal collagen cross-linking.

Intrastromal Corneal Ring Segments (ICRS)

1. ICRS involves inserting small plastic segments into the cornea to act as splints, physically improving the irregular corneal shape and enhancing corrected vision. This procedure is suitable for individuals with advanced keratoconus who find it difficult to correct their vision with glasses or contact lenses.

2. For younger patients, corneal cross-linking can be performed before or simultaneously with ICRS implantation.

3. The drawbacks of this procedure include that it may take over a month for vision to stabilize post-surgery, and night vision may worsen. In the long term, corneal opacity may develop, sometimes requiring the removal of the corneal rings.

4. Even after ICRS surgery, keratoconus may progress in individuals with a habit of rubbing their eyes, so it’s essential to avoid eye rubbing.

ICL

1. ICL is not effective in treating keratoconus itself.

2. If keratoconus is in its early stages or is suspected but unlikely to progress to severe keratoconus, ICL surgery may be an option.

3. For young patients with keratoconus, once keratoconus progression is controlled through appropriate treatments such as corneal cross-linking or ICRS implantation, they may undergo ICL surgery.

4. The uncorrected vision expected after ICL surgery for keratoconus may not match that of a normal cornea.

5. The expected corrected vision after ICL surgery varies significantly depending on the progression of keratoconus. It may not reach the quality achieved with glasses or hard lenses before surgery.

6. After ICL surgery, it may be possible to live without glasses, but for advanced keratoconus, vision similar to that achieved with specialized contact lenses may not be achievable.