Written by ID Eye Clinic
2025.02.20
With the increasing use of electronic devices, vision deterioration is occurring at a younger age, leading to earlier dependence on glasses and contact lenses. Among these, contact lenses are often preferred over glasses due to their aesthetic advantages. However, prolonged use of contact lenses can limit oxygen supply to the cornea, increasing the risk of bacterial growth and corneal swelling. Additionally, falling asleep while wearing contact lenses can lead to the formation of new blood vessels in the cornea, raising concerns about complications. If the eyes are dry during lens removal, the corneal epithelial cells may peel off along with the lens. While the corneal epithelium naturally regenerates, artificially induced damage can lead to infections, making proper lens hygiene essential. Therefore, while contact lenses serve as an effective vision aid when used correctly, improper management can have serious consequences for eye health. For individuals with astigmatism, a more sustainable approach to vision correction includes specialized toric lenses, orthokeratology (overnight corrective lenses), or surgical options such as SMILE LASIK, LASIK, or LASEK, depending on the individual's eye condition.
However, individuals with high astigmatism or high myopia may face limitations when choosing a surgical option. This is because greater vision impairment requires more corneal tissue removal, which can affect the safety and feasibility of the procedure. Myopia, commonly known as nearsightedness, occurs when light focuses in front of the retina rather than directly on it. In recent years, increased engagement in close-up activities such as reading, watching TV, and using smartphones has contributed to the early onset of myopia in younger individuals. When astigmatism accompanies myopia, vision deterioration tends to be more severe, leading to greater visual distortion and difficulty in achieving clear focus.
Astigmatism is a refractive error in which the eye’s refractive power is uneven across different directions, preventing light from converging at a single focal point. Instead, light is focused on two or more points, leading to blurred or distorted vision. While most people have some degree of astigmatism, higher severity results in greater visual discomfort and difficulty in daily activities.
Astigmatism is primarily influenced by genetic factors, but it can also develop due to external or medical conditions. Some common causes include: Congenital factors: Genetic predisposition to corneal irregularities Eyelid conditions such as ptosis (droopy eyelid), where the eyelid presses against the eye Corneal diseases that alter the shape and smoothness of the corneal surface Keratoconus, a progressive condition where the cornea thins and bulges into a cone shape, leading to irregular astigmatism.
When myopia (nearsightedness) and astigmatism coexist, a higher degree of vision impairment requires more corneal tissue removal for correction. In LASIK, which involves creating a corneal flap to reshape the underlying tissue, sufficient corneal thickness must remain after surgery to maintain eye stability. If the residual corneal thickness is insufficient, certain surgical options may be limited due to the risk of corneal weakening. If corneal tissue removal limits the feasibility of vision correction surgery, LASEK astigmatism correction can be considered as an alternative.
• 3(+): Extreme astigmatism • 3(-) ~ -2(+): High astigmatism • 2(-) ~ -1(+): Moderate astigmatism • 1(-) ~ 0(-): Mild astigmatism • 0: Normal The method of correction surgery may vary depending on the degree of astigmatism. In cases of high astigmatism or above, selecting a procedure that allows for sufficient residual corneal thickness can help reduce the risk of complications that may arise later. If minimal-cut LASEK astigmatism correction is applied, regression can be prevented.
Regression does not mean that vision will deteriorate to its previous state, but since both myopia and astigmatism regression can occur together, it may lead to vision deterioration, requiring the use of glasses or contact lenses again as a compensatory measure. The purpose of vision correction surgery is to achieve good vision without the need for visual aids. Therefore, for those who do not wish to rely on glasses or contact lenses, options such as medication or enhancement surgery can be considered if the residual corneal thickness is sufficient. Regression occurs in approximately 4% of cases, and the greater the amount of corneal tissue removed, the higher the likelihood of regression. By applying minimal-cut LASEK astigmatism correction, regression can be prevented, reducing the possibility of requiring enhancement surgery.
Dry eye syndrome occurs when the balance of tear components is disrupted, leading to damage on the ocular surface. The less corneal tissue is removed, the lower the risk of nerve damage, which helps reduce the likelihood of developing dry eye syndrome. Conversely, if excessive tissue removal damages corneal nerves, the ability to sense dryness diminishes, leading to impaired tear production. Since LASEK astigmatism correction requires deeper corneal adjustments due to higher tissue removal, it is recommended to use a minimal-cut approach to prevent dry eye syndrome. Additionally, after vision correction surgery, the corneal surface becomes rough, causing the tear film to form irregularly and break down easily, leading to rapid tear evaporation and prolonged eye dryness. Minimal-cut LASEK astigmatism correction reduces thermal damage to the cornea and smooths the corneal surface using a laser, helping to prevent dry eye syndrome caused by tear film instability. When astigmatism is combined with the same degree of myopia, the amount of corneal tissue removal increases significantly. Moreover, if the astigmatic axis is not precisely corrected, accuracy decreases. Therefore, it was necessary to select equipment that could minimize tissue removal while ensuring an error-free process.
Therefore, instead of traditional LASEK, All-Laser LASEK is used to achieve a minimal-cut procedure. In conventional LASEK, corneal epithelium removal using alcohol and a medical brush resulted in a higher risk of corneal nerve damage due to the manual removal process. However, by utilizing a precise laser procedure, unnecessary corneal nerve damage is minimized, creating a safer surgical process. Additionally, corneal tissue removal has been reduced by approximately 5–20%, which not only decreases the potential complications of LASEK astigmatism correction but also reduces the affected area by up to 40%, significantly shortening the recovery period—one of the main concerns with traditional LASEK. For individuals who hesitated to undergo vision correction due to concerns about excessive tissue removal in cases of high myopia or astigmatism, or those worried about rare postoperative corneal haze, All-Laser LASEK can be a viable alternative.
LASIK can be performed if the corneal thickness is sufficient to leave an adequate amount of residual cornea. The Femto Z8 system is an advanced LASIK device designed to minimize corneal damage. It utilizes a state-of-the-art femtosecond laser to create the corneal flap with low-energy, ultra-fine laser pulses at a speed of 5000 kHz. This high-speed precision helps reduce corneal dryness during surgery, thereby lowering the risk of complications associated with LASEK astigmatism correction.
The most important aspect of LASEK astigmatism correction is ensuring precise centration to minimize corneal damage. While minor astigmatism may not cause significant vision fluctuations depending on axis alignment, in cases of high astigmatism, even a 1-degree misalignment can lead to considerable vision changes. Therefore, working with a clinic that carefully evaluates individual eye characteristics and develops the most optimal treatment plan is essential for achieving high satisfaction with astigmatism correction. Vision does not worsen overnight. It declines gradually over time, often without immediate notice. By proactively monitoring eye health and taking preventive measures, potential discomfort and complications related to vision deterioration can be significantly reduced in the future.
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