강남 닥터ICL안과의원 - 강남안과,렌즈삽입술,안내렌즈삽입술

LASIK became widely known in Korea from the 1990s after its FDA approval in the US in 1989. Since more than 30 years have passed since its introduction, those who had surgery in the early years may have experienced vision decline due to age-related presbyopia.

Myopia progression is closely related to eye length growth; generally, myopia slows down and stops as a person reaches adulthood. However, high myopia has been known to continue progressing even after reaching adulthood. Those with high myopia before LASIK may experience vision decline due to this progression. Generally, myopia classified as high is -6 diopters or more, but the WHO (World Health Organization) has recently tightened this classification to -5 diopters or more.

LASIK is a treatment that corrects myopia by removing part of the cornea's center with a laser to flatten its curvature. All humans have the ability to heal wounds, which means the cornea also undergoes recovery due to its biological tissue repair function. As a result, while vision improves due to the resection, it may regress when the resected area heals, leading to a paradoxical decline in vision. The more severe the myopia, the more tissue needs to be removed, increasing the likelihood of a thinner cornea and subsequent vision decline.

While vision may decline after LASIK due to the factors mentioned above, if there is sufficient residual cornea thickness and no abnormalities in corneal shape, laser reoperation may be feasible.

1) Residual Cornea Reoperation requires excess corneal tissue, which may not be available if a significant amount was removed during the first surgery or if the cornea was thin before surgery. In such cases, ICL surgery can restore vision. Unlike lasers, ICL uses its correction power, allowing anyone to recover vision regardless of residual corneal tissue.

2) Complications Laser reoperation involves reopening the previous surgical wound, applying laser treatment, and then restoring the flap. There is a tendency for previous wounds to not heal well, leading to complications such as epithelial cells entering under the flap, causing opacity and flap separation. This principle is akin to trying to reapply a sticker that has been removed.

3) Worsening Dry Eye Symptoms Reoperation with lasers reopens the flap, cutting the corneal sensory nerves, leading to temporary dry eye symptoms. While this typically improves over time, those with severe dry eye may experience exacerbated symptoms after reoperation.

4) Uncertain Outcomes Older individuals or those with significant regression tend to have less favorable outcomes after laser reoperation. In cases where there is sufficient corneal thickness, vision may be restored with a second surgery, but third surgeries are rare.

5) Light Scattering and Glare Removing corneal tissue during laser reoperation may increase higher-order aberrations (irregular astigmatism), causing many to experience light scattering or glare, particularly when driving at night. While this phenomenon may improve over time, it may be necessary to wear medication, sunglasses, or specialized polarized glasses at night to prevent dilated pupils.

6) Corneal Ectasia Laser reoperation may thin the cornea, leading to rare complications such as corneal ectasia. Corneal ectasia resembles keratoconus, where the lower cornea bulges. This can lead to significant irregular astigmatism, reducing the maximum correctable vision to the pre-surgery level, even with glasses or contact lenses. Treatment for corneal ectasia involves halting progression with corneal cross-linking and correcting the corneal deformation with intrastromal rings, but regaining good vision is practically impossible.

1) Residual Cornea Unlike LASIK, which alters the cornea's shape through resection, ICL is a surgery where a lens with corrective power (similar to glasses or contact lenses) is inserted to correct myopia. Over time, just as nails or hair grow back, the cornea can regenerate, but unlike glasses that don’t change size, ICL lenses do not decrease in effectiveness.

LASIK relies on corneal reshaping through laser resection; therefore, even if individuals have the same level of myopia, their sensitivity to laser resection and recovery response can vary. In contrast, ICL provides correction based on the lens's refractive power, so individuals with the same degree of myopia will have identical correction effects.

While LASIK creates a circular flap about 9mm in diameter, ICL uses a micro-incision of 2.8mm to insert the lens, resulting in less tissue damage and faster recovery, allowing for stabilized vision recovery soon after the procedure.