Managing problems with Radial Keratotomy

Managing problems with Radial Keratotomy

 

What is RK?

 

Vertical deep incisions are made into the cornea in a spoke like fashion. Each incision causes the cornea to bulge around the incision and at the same time flattening the center of the cornea. Therefore the power of the cornea decreases and myopia or nearsightedness can be treated. This technique was invented by the Russians and was popular in our country in from 1980 to 1995. Today it is no longer performed.

There  are  some  unique  problems  associated  with  Radial Keratotomy. The incisions decrease the tensile strength of the cornea. It’s shape and therefore the power become more responsive to the pressure within the eye. There is diurnal fluctuation of the pressure of the eye in normal people. It is usually highest in early morning and decreases during the rest of the day and night. As a consequence the cornea which has been weakened by RK is more curved in the morning and less so in the evening. The power is more in the early hours of waking and decreases over the next few hours. Therefore the vision for reading may be better in the morning but the distance vision improves during the day. The cornea bellows like the sail of a boat.

As the PERK or Prospective Evaluation of Radial Keratotomy study had found that the cornea continues to become weaker and flatter over the years after RK. The eye therefore continues to move from nearsightedness to farsightedness. The amount of diurnal fluctuation and progression towards hyperopia is proportional to the number of incisions made on the cornea and the thickness of cornea. Consequently the cornea, which has suffered 16 incisions, would be worse off than that which underwent only 4. Believe it or not some crazy barber surgeons made 32 or even more incisions on cornea. These corneas end up becoming weak and irregular in shape.

If we have to be successful with Prelex in such patients we have stabilize the fluctuations in vision and the drift towards progressive hyperopia. This can simply be achieved by aiming to make the eye a little nearsighted and let it progressively improve with passage of times. One eye may be made more nearsighted so as to achieve immediate functionality. The eye which is made which is aimed more towards zero can be made more spherical in future by laser.

There are many techniques available to decrease the fluctuation of post RK cornea. The incisions can be freshened and sutured. The gaps may also be filled with biological glue to increase the adhesion. A newer technique of crosslinking uses riboflavin activated by UV radiation to stiffen the cornea. This is being performed at certain centers only, which have access to this cutting edge technology.

In weak corneas a mechanical support may be given with intac ring segment.

One or a combination of these techniques may be utilized to achieve the  desired  result.  These  procedures  can  be  used  in conjugation with pi in eye.

In the worst case scenario a cornea transplant may be required.

 

What is AK?

 

Astigmatic Keratectomy is a transverse incision made in the mid- periphery of cornea to treat astigmatism. The incision is made in the steeper axis to relax the fibers and change the shape from oval to spherical.

 

What is LRI?

 

Limbal Relaxing Incisions- when AK is performed along the cornea margin. These incisions are longer and more stable; less effective but there are fewer side effects.

 

What is miniRK?

 

Mini RK is used to treat eyes with minimal myopia with vertical incisions avoiding the central zone of the eye. Today it is used to treat

around  one  diopter  of  nearsightedness  in  patients  who  are  not candidates for Lasik.

No blades please- we are American

The laser precision is equally useful in wound creation. The precise openings allow the entry and exit of instruments and insertion of the pi without undue stress and consequently inadvertent enlarging of the wound. This prevents wound leakage at the end of the case and faster healing.

Screen shot 2013-02-08 at 6.05.13 PMLet us look at the splitting of the lens by laser. It is important to realize this is done without any stress on the capsular bag or the zonular support system.

The opening in the lens bag or capsulorhexis is made first. This is followed by the patterned breakup of the lens. It can be cut into 2, 4 or 6 pieces. The center core may be delineated too. The depth of these lenticular cuts can again be controlled.

The depth of the cuts can be controlled in real time. The energy is delivered from the bottom towards the top. This allows gas generated by conversion of the lens material into plasma to escape as well allow the subsequent beam to work without interference from the gas bubbles. The option till now was to use sound energy. This can cause inflammation and affect the functioning of the cornea. In dense cataracts the bottom is difficult to perceive so the capsule can be accidentally ruptured. Again, the real time display and the ability to be precise and avoid the bottom of the bag is a boon when using the laser for cataract or Prelex procedure. Lets talk about breaking these hard lenses. It’s a real pain for the surgeon and patient alike to work on these cataracts with sound wave technology. It takes times and a lot of energy to accomplish this with traditional technology. This is where progress in laser technology will help even more in the future.

 

Askimo TV interview on Prelex

Can you explain what Presbyopia is and why it develops later on in adult life? What are bifocals and what kind of eye patients require them? What is the difference between bifocals and varifocals? How does PRELEX surgery treat Presbyopia and why is LASIK surgery not applicable in this case? Can the correction of Presbyopia with PRELEX surgery prevent any other eye disorders from developing in the future? All of these questions will be answered by:Dr. Rajesh Khanna – Ophthalmologist and Surgeon who is internationally recognized as a LASIK and refractive vision care specialist.

Astigmatism treatment with laser cataract surgery

the arcuate incisions for decreasing the astigmatism are made. Either one or two incisions can be made. The length, the distance from the center and the depth of each astigmatic keratotomy incision can be coordinated independently.

Screen shot 2013-02-08 at 5.58.15 PM

Screen shot 2013-02-08 at 6.05.58 PM

In the above pictures the bubbles serve asa guide to the location of the actual openings in the lens and cuts in the cornea. One can realize comparing the two pics how accurate the laser is. Here we have shown the lensx laser in action. The other lasers for cataract surgery are Vectus, catalys and lensar.

Laser assisted cataract surgery

Precision and safety has increased with the advent of femtosecond lasers for cataract and Prelex surgeries.In a painless procedure lasting under two minutes the laser can make openings in the eye. It can also make relaxing incisions to correct astigmatism. More exciting and new is that the laser can now make a desired size opening of the lens bag. Further it can break the lens into multiple pieces of desired shape and size. This make it easier to remove the lens pieces with least amount of energy.

Screen shot 2013-02-08 at 6.04.12 PM

Engaging the docking mechanism. Patient looks at the central red light. Corneal cuts from previous radial keratotomy are visible.

Learn more by watching a video on laser cataract surgery being performed on a patient who had had previous radial keratotomy.

 

 

IndUS Business Journal features Prelex author

Issue Date:  November 2012, Posted On: 11/23/2012

Lasik specialist writes book on benefits of ‘Prelex’

“Prelex,” above and Khanna, below.
Beverly Hills Lasik surgeon Dr. Rajesh Khanna decided to follow in the path of Doctors Chopra and Gupta, and compile a book titled “Prelex,” which is receiving rave reviews on Amazon. As it is discussed in the book, the Prelex procedure allows individuals over 45 to see near, middle and distance in each eye (not monovision) without the use of glasses or contacts. This procedure also prevents the development of cataracts. Patients describe Prelex as, “miraculous” and “life changing.” According to Khanna, the book is aimed at all people above 45 years of age including baby boomers and seniors.

Khanna is board certified by the American Board of Ophthalmology. He has specialized training in LASIK, Prelex, Cataract and Corneal surgery from the University of Cincinnati. Khanna is known as the Lasik surgeon to the stars, as he has performed over 10,000 vision correction procedures on many Olympic medal winners and Hollywood personalities like Disney stars Brenda Song and Corbin Bleu, “Hercules” Kevin Sorbo, UFC champion fighter Bas Rutten, and Butch Patrick who played Eddie Munster. He also performs Intacs Surgery for Keratoconus. Khanna is a voluntary member of the UCLA faculty, as well as of the American Academy of Ophthalmology and the American Society of Cataract and Refractive surgery. The Khanna Vision Institute has centers in Beverly Hills and Westlake Village.

To see the actual article click here

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100 seniors in 1000 oaks

Acorn_11-01_Issue_pg45

More than 100 seniors came to Thousand Oaks on Oct. 18 to hear a talk by Dr. Rajesh Khanna, a board-certified and internation- ally recognized Lasik surgeon who specializes in disorders of the eye.

The event at Los Robles Hos- pital was part of the hospital’s ongoing health chat series that features a variety of doctors offer- ing medical advice to community members.

Khanna discussed the signifi- cance and development of cata- racts and the most promising and advanced treatment called Prelex, a replacement of the eye’s lens.

Khanna began his discus- sion by explaining the structure of the eye and the changes that occur over time. One of the most common eye aliments is cataracts. More than 20.5 million Americans over the age of 45 are affected by cataracts each year.

A cataract is the natural dete- rioration of the lens and can cause blurry vision. If the cataract is advanced it can make it extremely difficult to see.

Common treatments that are often recommended include drops and vitamins, but Khanna said research shows that neither of those options is useful. Instead, he suggests the cataract procedure.

Forms of cataract surgery have been in existence for hundreds of years, but procedures weren’t refined until modern cataract surgery was developed about 40 years ago. Recent advances in refractive cataract and Prelex procedures take the treatment to a new level.

Laser-assisted cataract sur- gery, for example, can also cor- rect astigmatism. Cataract surgery can be performed even in the presence of dry macular degen- eration.

Khanna also talked about an- other benefit of Prelex in which presbyopic implants, such as

Restore, Tecnis and Crystalens, are used as the eye’s new lens and are able to improve its ability to see up close.

Presbyopia is a condition in which the lens of the eye loses its ability to focus on close-up objects.

People over 50 who become dependent on reading glasses are excellent candidates for Prelex surgery, said Khanna, whose new book, “Prelex,” is available on Amazon.com.

Khanna’s website is www. khannainstitute.com. His offices are in Thousand Oaks and Bev- erly Hills.

Pi in the eye

Pi is the acronym coined by the author of the book Prelex.  It is  a shortened form of presbyopic implants. These implants are inert plastic (acrylic or silicon to get technical) which reverse presbyopia or ageing eyes permanently.

They sit quietly working 24/7 without asking for a cost of living hike. 24/7 you ask? Well you got to see your dreams clearly too.

There are two kinds of Pi. Accommodative and multifocal. They have a different mode of actions. In the book prelex there is a chapter devoted to pi in the eye. This chapter discusses in detail the advantages of each type of Pi.

Remember you eat pie and see with pi.