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Contact Lenses After LVC Surgeries:

 

Gas permeable (GP) or hybrid contact lenses may improve the eyesight of people who have less-than-perfect results from LASIK or other refractive surgery, especially when another surgical procedure or enhancement is not possible.


The smooth, rigid surface of these lenses can correct optical imperfections that eyeglasses and soft contacts can't address, making gas permeable contact lenses or hybrids the best choice if you're looking for the sharpest vision possible.


Despite high refractive surgery success rates, LASIK, PRK and other laser vision correction procedures don't produce perfect vision for everyone. Your results depend a great deal on the unique way your corneas respond to laser energy and how they heal after surgery.


Glare, halos and starbursts around headlights and street lights can sometimes be a problem after refractive surgery. LASIK and other procedures can also sometimes cause irregular astigmatism, with accompanying blurred and/or distorted vision.


For most people who have less-than-perfect vision after refractive surgery, problems are quite mild and usually tolerable. But for others, post-surgery vision problems can decrease overall quality of life with side effects such as eyestrain, headaches and difficulty driving at night.


Post-Surgery Contact Lenses Indications:
LASIK and other laser vision correction procedures reshape your eye's front surface by removing microscopic amounts of tissue from the cornea. Occasionally, this can cause irregularities in the shape of the cornea that can make your vision less distinct after surgery than it was when you wore glasses or contact lenses before the procedure.


These irregularities sometimes can be corrected with a follow-up laser procedure called an enhancement. But if your cornea is too thin for a second surgery, or other problems rule out an enhancement procedure, GP or hybrid contact lenses may be your best solution.


Post-Surgery Gas Permeable Contact Lenses


Because gas permeable contacts are rigid, they maintain their shape on the eye - unlike soft lenses that drape the cornea, losing their shape.


That's significant because the space between the cornea and the back surface of a GP lens is filled with tears. This "lake" of tears covers all the tiny irregularities (aberrations) on the cornea's surface. The smooth front surface of the GP lens then optically replaces the irregular corneal surface, eliminating blur and visual distortions.


In comparison, soft contact lenses are pliable and conform to the surface of the cornea. This means soft lenses can't achieve the same aberration-cancelling effect that GP lenses provide.


And conventional eyeglasses, which do nothing to change corneal irregularities, cannot correct the vision problems those irregularities cause. These glasses can correct only the basic refractive errors - nearsightedness, farsightedness, and regular astigmatism.


Special Contact Lens Designs for Post-Surgery Fittings
Because LASIK and other laser refractive surgery can significantly alter the shape of the cornea, fitting contact lenses on a post-surgery eye is more challenging than fitting lenses on a normally shaped cornea. Instead, special GP lens designs are usually required in these circumstances.
These modified designs may include a larger lens diameter, aspheric optics or a design where the center of the lens is significantly flatter than the periphery (called a reverse geometry design), similar to the gas permeable lens design used for orthokeratology to correct nearsightedness without surgery.


Special computerized instruments (not needed for regular contact fitting) are usually required to obtain highly accurate, point-to-point measurements of the post-surgery corneal surface to obtain the best possible fit for vision correction. These instruments, called corneal topographers or aberrometers, use the same LASIK technology that measures the cornea before laser vision correction.


Because of these added complexities, contact lens fittings after refractive surgery are typically more time-consuming and involve a higher fee than regular contact lens fittings. Also, if you've never worn GP lenses before, be aware that it takes longer to adapt to them than to soft contacts. You may have to wear the lenses at least part-time every day for several weeks before they feel completely comfortable.


Fitting GP contacts on an eye that has undergone refractive surgery requires special skills similar to those needed to fit lenses on an eye with an irregular cornea, such as an eye with keratoconus or one that has had a cornea transplant procedure called a penetrating keratoplasty. Several lens modifications may be required to achieve the optimum fit, comfort and visual acuity.


New Technologies: Hybrid Contact Lenses and Wavefront Glasses
Recently, two new eyewear technologies were introduced that offer an alternative to GP contact lenses for correcting irregular astigmatism and higher-order aberrations after eye surgery.


One technology involves a type of contact lens that has a rigid gas permeable optic zone in the center and a soft outer skirt. Called SynergEyes, these new "hybrid" lenses may offer the best of both worlds: the aberration-correcting optics of a rigid GP lens, combined with comfort that often rivals that of soft contact lenses. Early reports indicate SynergEyes lenses may be equally as effective as GP lenses in correcting aberrations after surgery, but may be easier to adapt to and wear.


The second new technology is a type of eyeglass lens that uses LASIK-style wavefront measurements to create a custom lens design for each person. In addition to correcting common refractive errors like nearsightedness, these new eyeglass lenses can also correct some degree of irregular astigmatism and higher order aberrations (HOAs) caused by corneal irregularities.


Studies suggest that these new wavefront lenses, called iZon High Resolution Lenses, provide sharper vision at night than conventional eyeglass lenses and may be an acceptable alternative to GP or hybrid GP/soft contact lenses for the correction of post-surgical vision problems.

 

 

 

 

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