LASIK for High Myopia: Is 90UM Safe for Corneal Thickness? - Ophthalmology

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When considering LASIK surgery for high myopia, particularly in cases where the refractive error is as significant as -14.00 diopters in one eye and -16.00 diopters in the other, it is crucial to evaluate the corneal thickness and the surgical technique being employed. In your case, the measured corneal thickness of approximately 540 micrometers (µm) is a critical factor in determining the safety and appropriateness of the LASIK procedure.

LASIK surgery involves reshaping the cornea to correct refractive errors, and the amount of tissue removed during the procedure is essential to ensure that the cornea maintains its structural integrity. The use of a 90µm (micrometer) microkeratome blade for creating the corneal flap is a specific choice that can be beneficial in cases of high myopia. This technique allows for a thinner flap, which can help preserve more of the corneal tissue beneath.

In general, a safe corneal thickness after LASIK should be at least 250µm to 300µm to maintain corneal stability and prevent complications such as ectasia, which is a progressive thinning and bulging of the cornea. Given your initial corneal thickness of 540µm, if the surgeon removes a flap of 90µm, the remaining corneal thickness would be approximately 450µm after the flap is created. This remaining thickness is still within a safe range for most patients, especially considering the high degree of myopia being treated.

However, it is essential to consider the amount of tissue that will be ablated during the LASIK procedure. The amount of corneal tissue removed during the ablation process is determined by the degree of myopia being corrected. For high myopia, the ablation can be significant, and it is crucial to ensure that the total remaining corneal thickness (after flap creation and ablation) does not fall below the safe threshold.

In your case, the decision to proceed with LASIK using a 90µm flap should be made with careful consideration of the following factors:
1. Preoperative Assessment: A thorough preoperative evaluation by an experienced ophthalmologist is vital. This includes assessing the corneal topography, pachymetry (corneal thickness), and overall eye health.

2. Surgical Technique: The choice of using a 90µm microkeratome blade indicates that your surgeon is taking a conservative approach to preserve corneal tissue. This is particularly important in high myopia cases.

3. Postoperative Care: Following LASIK, proper postoperative care and follow-up appointments are essential to monitor healing and ensure that the cornea maintains its structural integrity.

4. Potential Risks: As with any surgical procedure, there are risks involved, including dry eyes, glare, halos, and potential complications related to corneal healing. Discuss these risks with your surgeon to understand how they apply to your specific situation.

5. Long-term Outcomes: High myopia can be associated with other ocular conditions, such as retinal detachment or glaucoma. It is important to have a comprehensive discussion with your eye care provider about the long-term management of your eye health post-surgery.

In conclusion, while a corneal thickness of 540µm with a 90µm flap for LASIK in the context of high myopia appears to be within a safe range, it is crucial to have a detailed discussion with your ophthalmologist. They can provide personalized advice based on your specific eye anatomy, the degree of myopia, and the surgical plan. Always ensure that you are comfortable with the information provided and that all your questions are addressed before proceeding with the surgery.