What are Intacs corneal ring segments?
Intacs are small ring segments manufactured by Addition Technology. Intacs aid in the cure of Keratoconus. Intacs come in different thickness, ranging from 210 microns to 450 microns. They have an inner diameter and outer diameter. At the end of the segments are holes, which help in implantation of the Intacs.
Intacs ® Corneal Implants are actually an ocular medical appliance developed for the reduction or elimination of myopia and astigmatism in individuals with Keratoconus (KC). They are used to ensure that the practical vision may be restored and the need for a corneal transplant procedure can possibly be postponed. When placed in the corneal stroma, outside of the patient’s main optical area, the item reduces the cone by flattening the cornea, and for non-central Keratoconus, rearranges the cone centrally. Intacs segments are designed to be put in the periphery of the cornea, at roughly two-thirds depth, and are operatively inserted through a tiny radial laceration in the corneal stroma.
Intacs Corneal Implants are composed of two clear sections, each having an arc size of 150 ° (see layout below). They are manufactured from polymethylmethacrylate (PMMA) and also are readily available in six densities: 0.210 mm, 0.250 mm, 0.300 mm, 0.350 mm, 0.400 mm and also 0.450 mm. In order to minimize the myopia and the uneven astigmatism induced by Keratoconus, 2 Intacs sections ranging from 0.210 mm to 0.450 mm might be implanted depending upon the patient’s preoperative show refraction spherical matching (MRSE), the alignment of the cone as well as the level of uneven astigmatism. The product is designed with a fixed external diameter and also size. Intacs Corneal Implants have two positioning openings, located at each end of the section, to help in surgical control.
Indications for Intacs Implantation
Intacs ® Corneal Implants are intended for the decrease or removal of myopia, and astigmatism in people with Keratoconus eye disease, who are no longer able to achieve ample vision with their contact lenses or spectacles. The goal is for the vision to be recovered and have the demand for a corneal transplant treatment potentially be deferred. The certain part of Keratoconic patients proposed to be treated with Intacs Corneal Implants are those people:
1. Experienced a progressive deterioration in their vision, such that they can no longer achieve sufficient practical vision every day with their contact lenses or eyeglasses
2. Are 21 years old or older
3. Have clear central corneas
4. Have a corneal density of 450 microns or better at the suggested laceration website
5. Corneal transplantation as the only remaining alternative to boost their functional vision
Planning Intacs Implantation
There are 2 primary criteria used in establishing the medical nomogram pertaining to making use of Intacs Corneal Implants for Keratoconus. The initial requirement is whether the cone is centered or uncentered (uneven cone). Keratoconus, which is centrally existing as determined by a topographic map, will certainly require 2 Intacs sections of the same density. The thickness of the Intacs segments to be utilized is figured out based upon the preoperative spherical matching of less than or equal to -3.00 D or above -3.00 D. This would also be put on global Keratoconus in which the Keratoconus is centered but its circumference prolongs beyond 5.0 mm from the center.
As for crooked cones, we need to evaluate the level to which the cone is uncentered. This is done by assessing a topographic map of the cornea. Moderate asymmetry exists when the cone is off-center in placement at the 3.0 millimeter ring on the topographic map. High asymmetric cones are normally 5.0 millimeters or more off-center, as shown on a topographical map. In each of these situations, two various densities of Intacs sections are utilized. The Intacs thicknesses made use of will certainly depend on whether the preoperative spherical matching is less than or equal to -3.00 D or greater than -3.00 D. The thicker Intacs segment is recommended to be positioned inferiorly as well as the thinner Intacs section is to advised be positioned par excellence.
How are Intacs ring segments implanted?
Intacs are inserted into channels created in the cornea. The channels can be created by Intralase laser, the same laser used to make flaps for Lasik. The channels can also be made with the prolate mechanical system. There are two models of Intacs – Classic and SK. How do Intacs work to treat Keratoconus? Keratoconus is central thinning and weakness of cornea. This abnormal cornea is not able to withstand the internal pressure of the eye and bulges forward. This bulging cornea is also acted upon by gravity, therefore the apex of the ectatic cornea falls downward. Intacs are inserted at a distance of 7 mm from the center of the cornea. They push up and stretch the bulging apex of the Keratoconus cornea. This brings the apex up in the line of sight. Can Intacs be removed? Rarely, the Intacs have to be removed but it is a relatively simple procedure if needed. The entry wound is freshened, the holes at the end of Intacs are engaged and the Intacs pulled out.
Intralase laser is a high-energy small burst laser, which can create a channel in the cornea. The surgeon has the control to set the dimensions for this channel. This is a circular path created by the Intralase using special proprietary software from Abbot Medical. The depth of the channel is of course the most important factor and can be set by the Intacs surgeon. Usually with the Intralase method, the Intacs can be placed deeper, at 90% depth of the cornea with 50 to 100 microns left intact below the Intacs. This yields the best chance for the Intacs ring segments to work to treat Keratoconus and the least chance for extrusion from the surface.
The corneal surgeon will also need to set the inner and external diameter for the channel. These dimensions vary based on the thickness of the Intacs ring segments, that is 210 or 350 or 450 microns. Again, the commonly used numbers are 6.8 mm for internal and 7.6 mm for external diameter. Finally, keratoconus surgeon needs an entry into this channel. The software allows the doctor to set the location for this vertical incision. The Keratoconus surgeon, with experience in Intacs insertion, would usually set this at 90 degrees from where he wants the center of the Intacs to be finally placed.
The positioning of the cut will be commonly temporal at the axis of positive cylindrical tube; however, it may differ depending on the location of the cone, as well as the amount of Keratoconus existing in the eye to be treated. The Intacs sections are to be positioned equidistant on each side of the laceration. The Intacs product has been designed to permit substitution of the product for a different thickness or removal, even years later, if desired.
Once the channels are created, the eyes are prepped with betadine and draped. The Intacs are inserted and the incision is sutured. This is one of the latest methods to treat Keratoconus eye disease..
Before and After Intacs
Are Intacs for everyone?
Intacs were originally used for treatment of myopia. With the advent and popularity of wavefront Lasik, Intacs are rarely used for correcting nearsightedness. Today, they are mainly used for the treatment of Keratoconus.
Contraindications to implantation of Intacs
Intacs corneal implants for Keratoconus are contraindicated in the following situations:
1. Individuals who have abnormally slim corneas, or that have a corneal thickness of 449 microns or less at the suggested incision site
2. People with collagen vascular, autoimmune or immunodeficiency illness
3. Expecting or nursing women
4. The presence of ocular problems, such as persistent corneal dystrophy which may increase future complications
5. People who are taking several of the following drugs – Isotretinoin (Accutane1) or Amiodarone Hydrochloride (Cordarone2)
6. Patients who have Fuchs’ dystrophy, or have suspicious endothelial cell deficiency are not prospects for Intacs corneal implants