Corrective Laser Eye Surgery After LASIK

If you undergo LASIK in your 20s or 30s and achieve perfect vision, it will not prevent you from being unable to focus at all distances in your 40s or 50s. This inability to focus across distances is called presbyopia, and it cannot be treated by conventional corrective laser eye surgery.

However, there exists technological advancements in corrective laser surgery that address presbyopia — some in the development stage, others already approved by the US Food and Drug Administration (FDA).

One of presbyopia’s first symptoms occurs when small print appears blurry from a distance that you used to find comfortable. Ophthalmologists vary in their opinion regarding the cause of presbyopia. Some suggest it is the result of a stiffening of the lens that corrective laser surgery does not affect. Others say that it could be the result of continued lens growth or eye muscle atrophy.

Wearing reading glasses, bifocals, or multi-focals used to be enough. But in the age of corrective laser eye surgery, people naturally look for surgical remedies.

Monovision Using LASIK

Monovision is an FDA-approved procedure in which a person with presbyopia is made to use one eye for viewing things at a distance and the other for close-up viewing. It was derived from the procedure used on contact lens wearers, but now has applications on LASIK and other types of corrective laser surgery.

Using LASIK, a patient with presbyopia will receive corrective laser surgery on one eye for distance vision, and on the other for near vision, which effectively gives the presbyopic person one eye with worse than 20/20 vision.

Since the two eyes are no longer teamed, this means poorer vision and lessened perception of depth, which effects are more pronounced when light is insufficient or when engaged in tasks that need keen vision. So glasses or contact lenses may still be needed when:

• Driving at night


• Operating heavy equipment


• Reading fine print over extended periods

Monovision Using CK

CK (Conductive Keratoplasty) shrinks the collagen around cornea with low-level radio-frequency energy, effectively making the center of the cornea steeper and elongating the eyeball.

In 2002, the FDA approved CK for temporary reduction of farsightedness. In 2004, the FDA approved CK for temporary near vision treatment in presbyopic persons.

The advantage of CK is that it is less invasive than corrective laser eye surgery. Moreover, the side effects are minor and temporary (tearing, fluctuating vision, foreign-body sensation).

Procedures in the Development Stage

LTK (Laser Thermal Keratoplasty) employs a mild laser heat in a 3-second procedure to shrink collagen around the cornea. The results are similar to CK’s.

SRP (Surgical Reversal of Presbyopia) with SEBs (Scleral Expansion Bands) employs the insertion of 4 plastic polymethyl methacrylate segments below the sclera. The effect is an increase in distance between the lens-focusing muscles and the lens.

Researches say that this extra distance makes the muscle tighter, allowing it to focus the lens better. Research was done on five patients, who were able to read fine print after the insertion of expansion bands.

Clinical trials will still continue through the next months, since improvement in the subjects’ vision was not yet consistent.