LTK (Laser thermal keratoplasty) uses a holmium laser to shrink the collagen fibers of the cornea and results in a “steeper” cornea. It is used for lower amounts of hyperopia and does not require a creation of a flap.
CK (Conductive keratoplasy) uses a radiofrequency probe to shrink collagen fiber rather than a holmium laser in LTK. The probe is manually inserted into the cornea.
Intacs (Intrastromal corneal ring segments) are two flexible half rings. They
are inserted into the cornea to treat mild amounts of myopia. The implants can
be removed. They can also be used in LASIK patents with a residual refractive
error that cannot be corrected with additional laser treatment due to too thin
a cornea and some keratoconus patients. The intrastromal tunnels can now be
made with the Intralase™ making the procedure safer.
Phakic IOLs are placed inside the eye. They are either placed in front of or behind the iris. They are usually used to correct severe refractive errors and may be combined with excimer laser correction (Bioptics). There is an increased risk of complications compared to laser vision correction since this is an intraocular surgery. [Return to PRELEX]
Refractive Lensectomy is essentially a cataract operation in a patient without a cataract. It is used to treat severe refractive errors. There is an increased risk of complications compared to laser vision correction since this is an intraocular surgery. In addition, there is a loss of accommodation and an increased risk of retinal detachments in severely myopic patients.
PRELEX (Presbyopic lens exchange) is the use of
a multifocal IOL in a refractive lensectomy to allow a range of vision from
distance to near. It can also correct refractive errors. See Refractive Cataract
surgery.
[Return to PRELEX in Laser Vision Correction 101]
Bioptics is a term used to describe the combination of excimer laser correction and clear lens extraction or Phakic IOL. This procedure is used in the eyes very large refractive errors. There is an increased risk of complications since this is an intraocular procedure.
Refractive Cataract Surgery is a cataract surgery technique with special attention
made to reduce or eliminate the need for glasses (at one distance for a monofocal
IOL). This is accomplished by specialized more accurate biometry (calculation
of IOL power) and the reduction or elimination of corneal astigmatism. The elimination
of corneal astigmatism is considered a refractive procedure and is not paid
by most insurances and Medicare. The astigmatism can be reduced or eliminated
with a limbal relaxing incision or with an excimer laser.
Vision with a multifocal IOL (Array® Multifocal lens) is similar to wearing
progressive lenses. It allows a range of vision from distance to near. It offers
good far vision, like a monofocal lens, good intermediate vision (from two to
five feet), and good near vision with less dependence on glasses or bifocal.
About 90% of patients can read small print without glasses. 50% of patients
do not use glasses at all and 50% use glasses occasionally. Array lens patients
experience more glare at night than monofocal patients.
The multifocal lens has multiple rings of different refractive power. A monofocal
lens has a lens with one refractive power.
CCD camera simulation of a monofocal lens versus an Array multifocal lens. Distance to the letters increase from left (near about 16 inches) to right (distance about 12 feet).
Thelma McGugan, an artist and Array patient, created these illustrations. Of the visual perception in the darkness during the immediate post-op phase, Ms. McGugan says: “At this point everything had glare, as in the road placement of this picture. I had difficulty judging space and distance. There seemed to be an outline of light around everything.” At the tree-month post-op period, she had adjusted to the slight glow around headlights. “I don’t notice them anymore unless I look for them,” she says. “Also I don’t have depth-control problems. This surgery was well worth a slight glare at night. I’d do it again without the slightest hesitation.”
Hyperopic patient tend to do better than myopic patients. Hyperopic cataract patients have poorer uncorrected distance and near vision where as myopic cataract patients tend to have better near vision.
Learn more about the Array Lens
Limbal
relaxing Incision(s) can be performed at the same time as a cataract extraction
or later to reduce or eliminate astigmatism. Small incisions are made at the
limbus (edge of cornea). This is a refractive procedure and is not covered by
Medicare or most private insurances.
