Yes, LASIK surgery can occasionally result in overcorrection or undercorrection of vision, although such cases are relatively rare.
These outcomes typically occur due to the laser removing too much or too little corneal tissue, which can leave patients with imperfect vision correction.
To fully understand why these results sometimes happen, what can be done to mitigate the risks, and how they are addressed, you’ll need to start with the basics of LASIK surgery, its mechanism, and its limitations. This blog aims to explore these topics in-depth and provide detailed, factual insights into overcorrection and undercorrection in LASIK procedures.
What is LASIK?
LASIK (Laser-Assisted In-situ Keratomileusis) is a widely used refractive eye surgery designed to correct common vision problems like myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The procedure involves reshaping the cornea—the transparent front layer of the eye—so light entering the eye is properly focused onto the retina. This leads to clearer vision, often eliminating or reducing the need for glasses or contact lenses.
How Does LASIK Work?
The LASIK procedure is typically quick and often completed within 30 minutes. It involves these key steps:
- Creating a Corneal Flap: Using a microkeratome or femtosecond laser, the surgeon creates a thin flap on the cornea’s surface. This flap is then gently folded back to expose the underlying corneal tissue.
- Reshaping with an Excimer Laser: An excimer laser precisely removes microscopic amounts of corneal tissue, reshaping it based on the patient’s specific refractive error.
- Repositioning the Flap: After the cornea is reshaped, the flap is laid back down, acting as a natural bandage during the healing process.
The precision of the excimer laser plays a critical role in achieving the desired vision correction. Despite the high-tech nature of the procedure, there are factors that can occasionally lead to overcorrection or undercorrection.
What is Overcorrection in LASIK?
Overcorrection occurs when the laser removes too much corneal tissue, resulting in the refractive error being overcompensated. For example:
- A myopic (nearsighted) patient may end up farsighted after surgery.
- A hyperopic (farsighted) patient may end up myopic.
This issue can lead to vision symptoms such as blurred vision, difficulty focusing on nearby or distant objects, and an overall sense of visual discomfort.
Why Does Overcorrection Happen?
There are several reasons why overcorrections occur, including:
- Variations in Healing: Each individual heals differently. Some people’s corneas heal in a way that amplifies the effect of the laser correction.
- Miscalculations of Laser Settings: Though modern LASIK technology is highly advanced, errors in calibration or patient data inputs can lead to overcorrection.
- Thin Corneas: Patients with thinner corneas are at greater risk, as the amount of tissue that can be removed is limited, potentially making calculations imprecise.
- Surgeon Variability: While LASIK surgeons are extensively trained, variations in technique or judgement can occasionally lead to undesired outcomes.
What is Undercorrection in LASIK?
Undercorrection, on the other hand, occurs when the laser doesn’t remove enough corneal tissue, leaving the initial refractive issue only partially corrected. Patients may find that their vision is improved but still not optimal.
Why Does Undercorrection Happen?
Similar to overcorrection, undercorrection has multiple possible causes:
1. Suboptimal Laser Calibration:
If the excimer laser settings are slightly off, it may not remove the precise amount of corneal tissue required.
2. Patient-Specific Variables:
- Eye shape and corneal thickness can affect outcomes.
- Pre-existing conditions like dry eyes or irregular astigmatism can also play a role.
3. Delayed Healing:
A slower healing response may diminish the effects of the corneal reshaping performed during LASIK.
4. Strong Refractive Errors:
Patients with extreme myopia, hyperopia, or astigmatism may require more than one procedure to achieve the desired level of correction.
How Common Are Overcorrection and Undercorrection?
Both overcorrection and undercorrection have become less frequent with advances in LASIK technology, but they are not entirely unavoidable.
According to published research, around 1-3% of LASIK patients may experience significant overcorrection or undercorrection. Newer technologies, such as wavefront-guided LASIK and topography-guided LASIK, have significantly minimised these risks by offering highly individualised correction and decreased error margins.
Signs and Symptoms of Overcorrection or Undercorrection
If you’ve undergone LASIK and experience any of the following, you may want to consider a visit to your surgeon:
- Blurred or distorted vision
- Difficulty focusing on objects at certain distances
- Visual fatigue or headaches
- Persistent glare, halos, or starbursts around lights, especially at night
These symptoms may weaken over time as your eyes heal, but in some cases, they may require additional intervention.
Managing and Treating Overcorrection or Undercorrection
The good news is that both overcorrection and undercorrection are usually manageable or correctable. Here are some common solutions:
1. Enhancement Procedures
- If the original LASIK surgery didn’t achieve the desired results, you might be eligible for a LASIK enhancement. This involves performing a secondary procedure to further reshape the cornea.
- Surgeons typically wait for at least 3-6 months after the initial surgery to allow your vision and cornea to stabilise.
2. Eyeglasses or Contact Lenses
- For minor overcorrection or undercorrection, wearing glasses or contacts may be an easy and non-invasive solution.
3. Refractive Lens Exchange (RLE)
- For severe cases, RLE may be recommended as an alternative to further corneal surgeries. This procedure entails the replacement of the eye’s natural lens with an artificial intraocular lens.
4. Medicated Eye Drops
- Especially for overcorrection, where healing might enhance the refractive issue, eye drops can be used to manage symptoms and reduce inflammation.
5. Customised Wavefront Treatments
- Advanced technology, like wavefront-guided LASIK enhancement, allows for even more precise corrections tailored to the unique imperfections in your eyes.
Can Overcorrection and Undercorrection Be Prevented?
While there’s no way to fully eliminate the risk of overcorrection or undercorrection, the likelihood can be significantly reduced by taking these precautions:
1. Choose an Experienced LASIK Surgeon:
Your surgeon’s expertise and the technology used are crucial factors. Look for board-certified specialists with a strong track record and positive patient reviews.
2. Ensure Thorough Pre-Surgical Assessments:
Comprehensive eye exams and diagnostic tests help determine if you’re a good candidate and aid in accurate laser calibration.
3. Be Realistic About Expectations:
If you have a particularly strong refractive error, talk to your surgeon about the possibility of needing more than one procedure.
4. Follow Post-Surgery Care Instructions:
Proper aftercare is essential for optimal healing and results. Follow your surgeon’s recommendations closely during the recovery period.
Summing Up
While LASIK is one of the safest and most effective surgical options for vision correction, it is not without its risks and limitations. Overcorrection and undercorrection are two of the potential outcomes, but they are generally rare and manageable.
If you’re considering LASIK, it’s important to discuss all your questions and concerns with a qualified ophthalmologist. By understanding the risks and benefits, you can make an informed decision that’s right for your vision needs.
Remember, LASIK is not just about seeing better—it’s about feeling confident in the world around you. If you’re ready to take the first step towards clearer vision, schedule a consultation today and see the difference LASIK can make!
