Common Questions About Myopia Laser Surgery: What You Need to Know

Q: Common Questions About Myopia Laser Surgery: What You Need to Know

Hello： 1. <br>When assessing night vision, it is not necessary to be in complete darkness; an appropriately dim environment is sufficient. <br>The size of the pupil in total darkness is not particularly meaningful. <br>2. <br>Once the pupil reaches a certain size, it will not enl

Questions about myopia laser treatment?

Hello, Doctor.
I previously underwent some preoperative evaluations for myopia laser surgery and have a few questions to ask you:
1.
Is it necessary to measure nighttime pupil size in a very dark room? During my examination, some measurements were taken in a slightly dimmed room.
Would this be accurate?
2.
Does the nighttime pupil size increase the longer one stays in a dark room or dim environment?
3.
Can the pupil size measured after pharmacological dilation be used to estimate nighttime pupil size?
4.
If the anterior elastic layer of the cornea (Bowman's layer) is lost, will the cornea be more susceptible to infections in the future? Are there any significant adverse effects (side effects) that may arise? Additionally, there is a claim that the corneal tension provided by Bowman's layer is the strongest, and its absence may increase the likelihood of developing keratoconus.
Is this statement accurate?
5.
After the laser (trans-PRK) removes the superficial epithelial layer, will it regrow to be as complete and smooth as it originally was, provided there is sufficient healing time?
6.
Based on current technology, if one chooses to undergo trans-PRK to correct approximately 400-450 degrees of myopia, is there a high risk of developing corneal haze postoperatively?
7.
If myopia is overcorrected, resulting in hyperopia, is there still an opportunity for a corrective laser procedure? Thank you, Doctor!

Tank, 40~49 year old female. Ask Date: 2023/03/13

Dr. Gao Pilin reply Ophthalmology

Hello: 1.
When assessing night vision, it is not necessary to be in complete darkness; an appropriately dim environment is sufficient.
The size of the pupil in total darkness is not particularly meaningful.
2.
Once the pupil reaches a certain size, it will not enlarge further and will not change over time.
3.
Direct measurement of pupil size after dilation cannot be fully used to assess night pupil size, as dilation and dark conditions are not the same, and pupil size can vary from person to person.
4.
Loss of Bowman's layer (the anterior elastic layer of the cornea) may lead to decreased smoothness and stability of the corneal surface, thereby increasing the risk of corneal infection.
However, this should be a relatively rare occurrence, and the specific impact depends on the severity and location of the corneal damage.
Loss of Bowman's layer may affect the strength and elasticity of the cornea, which in turn can impact vision and corneal shape.
Some studies suggest that loss of Bowman's layer may increase the risk of developing keratoconus.
It is important to note that the cornea is a complex structure, making it difficult to predict the exact effects of a single factor.
If you are concerned about your corneal condition, it is advisable to consult with your surgeon.
5.
The trans-PRK surgical method removes the epithelial cells from the surface of the cornea to facilitate subsequent corneal correction surgery.
After the procedure, the epithelial cells will regenerate over time.
However, the regeneration process of the epithelial cells may be influenced by various factors, such as the amount of corneal tissue removed during surgery, postoperative corneal surface protection and treatment, individual health status, and lifestyle habits.
During the regeneration of epithelial cells, different conditions may arise, and it cannot be guaranteed that they will be the same as before.
6.
The incidence of corneal haze is related to multiple factors, including the surgical method, corneal thickness, surgical depth, and scale of the procedure.
In PRK surgery, the removal of the corneal epithelium may increase the risk of corneal haze.
However, modern PRK techniques utilize highly precise laser technology and corneal imaging techniques, which can significantly reduce the risk of corneal haze.
Correcting moderate myopia of 400-450 degrees is typically safe and effective with PRK surgery.
However, the occurrence of corneal haze post-surgery still depends on individual circumstances.
Factors such as insufficient corneal thickness, corneal damage during surgery, and improper postoperative care may increase the risk of corneal haze.
Therefore, a comprehensive eye examination is necessary before considering PRK surgery to determine suitability, along with adherence to proper postoperative care and regular vision check-ups.
7.
If you develop hyperopia due to overcorrection of myopia during laser eye surgery, it may be possible to correct the issue with a second laser eye surgery.
The decision to undergo a second procedure will depend on several factors, including the severity of your hyperopia, corneal thickness, and overall eye health.
Your ophthalmologist will evaluate your specific situation and provide recommendations based on your individual needs.
In some cases, if the degree of hyperopia is not significant, laser surgery may be used for correction.
In other cases, different types of surgery, such as lens implantation, may be recommended.
The above is a personal opinion, as I have not undergone laser refractive surgery, and my views may differ from those of the surgeon; please prioritize the surgeon's advice.

Reply Date: 2023/03/13

More Info

Hello! Thank you for your questions regarding myopia laser surgery. It's great that you're seeking more information to understand the procedure better. Let’s address your queries one by one.

1. Measurement of Pupil Size in Dark Conditions: Yes, measuring pupil size in a very dark room is ideal for accuracy. The pupil naturally dilates in low light conditions, and this measurement is crucial for assessing how your eyes will respond at night. If the measurement is taken in a slightly dim room, it may not reflect the maximum dilation, which could lead to inaccuracies in your surgical planning.

2. Pupil Dilation Over Time in Dark Environments: Yes, the longer you stay in a dark environment, the larger your pupils will generally become, up to a certain point. This is due to the photoreceptor cells in your eyes responding to the lack of light, signaling the iris to open wider to allow more light in. However, there is a limit to how much they can dilate based on individual physiology.

3. Measuring Pupil Size After Dilation: Measuring the pupil size after pharmacological dilation (using drops) can provide a good estimate of your night-time pupil size. However, it’s important to note that the dilation caused by drops may not perfectly mimic the natural dilation process, as it can sometimes cause the pupils to be larger than they would be in a natural dark environment.

4. Loss of the Anterior Elastic Layer (Bowman's Layer): The loss of Bowman's layer can indeed increase the risk of infection and other complications. This layer provides structural integrity to the cornea, and its absence may lead to a higher susceptibility to infections or other issues. The claim that it could lead to keratoconus (a condition where the cornea thins and bulges) is a topic of debate. While some studies suggest a correlation, it is not universally accepted that losing this layer directly causes keratoconus.

5. Healing After Trans-PRK: After a trans-PRK procedure, the epithelium (the outermost layer of the cornea) is removed, and it typically regenerates within a few days. With adequate healing time, the cornea can return to a smooth and regular surface, similar to its original state. However, individual healing responses can vary, and some patients may experience irregularities or haze during the healing process.

6. Risk of Corneal Haze with Trans-PRK: The risk of corneal haze after trans-PRK is generally low, especially with modern techniques and technology. However, it can still occur, particularly in patients with higher prescriptions or those who may not follow post-operative care instructions. Discussing your specific risk factors with your surgeon can provide more personalized insight.

7. Overcorrection and Re-treatment Options: If you experience overcorrection (for example, becoming farsighted after surgery), there may be options for retreatment, depending on the degree of overcorrection and the health of your cornea. A thorough evaluation by your eye surgeon will determine if a second procedure is advisable and what the potential outcomes might be.

In conclusion, it’s essential to have open communication with your eye care provider regarding these concerns. They can provide tailored advice based on your specific situation and the latest advancements in laser surgery technology. Always ensure that you follow pre- and post-operative instructions closely to optimize your recovery and visual outcomes. Thank you for your questions, and I wish you the best of luck with your surgery!

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