Diamond Ophthalmic Surgery Update

[Peter Goren]

Hello,

I am back in Budapest for a few months assisting my father-in-law's keratoconus research. There have been some very interesting cases during my absence.
I am currently working on a case report for a patient operated after PKP and would like to share some preliminary details as well as two topographic maps taken by the Tomey TMS IV.

25 years after a corneal transplant for keratoconus, a woman in her 40's noticed her vision was rapidly deteriorating. During the pre-op consultation, she only managed to count fingers within a few inches of the eye. Retransplantation was not possible due to the decreased number of endothelial cells in the cornea (the single layer of cells keeping the aqueous humor from entering the cornea). One year later, following a series of two operations to decrease astigmatism and myopia, her uncorrected vision is 20/60. The axial length of her eye is longer than the normal 23.5mm, thus complicating her keratoconus with myopia (nearsightedness). The attached topogaphy shows the pre-op state on the left and the one year control examination results on the right. More results will be posted on the clinic's website within the coming weeks.

Best Regards,
Peter Goren, MD
Artsybashev Clinic

[liam82]

Hi, what procedure is this?

[Peter Goren]

Hi Liam,

There are a few clinics in the world that currently offer diamond knife surgeries for keratconus patients. In general, radial keratotomy is absolutely contraindicated for keratoconus patients and I would never recommend traditional radial keratotomy for anyone. I can't speak for the other clinics, but the method that I am researching, although similar, has some key differences to earlier surgical techniques. The most important difference is that in radial keratotomy a diamond micrometer knife is set to a certain depth for a simple incision. The corneal thickness is constantly changing for a keratoconic cornea. Within 1 or 2 millimeters the thickness can vary by as much as 100 or 200 microns. Using that method microperforations are essentially guaranteed for keratoconus patients. Microperforations are mainly responsible for the terrible side-effects that many patients experienced after traditional radial keratotomy surgeries. I am researching a special technique that aims to avoid perforations and create very clean incisions. The incisions are designed to flatten the cone for keratoconus patients thus enhancing visual acuity. Ongoing research is showing that the cone continues to flatten for the vast majority of patients. This surgery is a very delicate procedure and complicated to perform without a tremendous amount of experience.

Dr. Goren

[liam82]

Thats fantastic, thanks for all that info

I look forward to hearing more sbout follow ups and stuff:)

[Peter Goren]

It is not uncommon for a physicians to be skeptical when they hear of the research underway at the clinic. As explained above, traditional radial keratotomy is absolutely contraindicated for keratoconus patients. Even upon seeing proof of the reduction of the cone after modified radial keratotomy some people have raised concerns that the keratoconus will reactivate and return the cornea to its preoperative state.

Today I assisted a follow-up for a patient two years and one month after he underwent bilateral modified radial keratotomy for stage II/III keratoconus. The results presented below show the progressive reduction in the cone that is observed in the majority of cases. The peak of the cone is labeled on the pre-op images for the both the right (OD) and left (OS) eye. The subsequent topographic maps show the diopter values measured at the exact same location for the 1 month, 1.25 year, and 2 year and 1 month follow-ups. The values obtained are as follows:

OD.jpg

(248.13 KiB) Not downloaded yet

OS.jpg

(245.59 KiB) Not downloaded yet

Right Eye (OD)
02/17/2010: 54.31 d
03/30/2010: 48.95 d
06/10/2011: 45.76 d
03/08/2012: 43.96 d

Uncorrected visual acuity (UCVA):
Pre-op: 20/200 (10%)
03/08/2012: 20/25 (80%)

Left Eye (OS)
02/17/2010: 53.65 d
03/30/2010: 47.07 d
06/10/2011: 41.90 d
03/08/2012: 40.43 d

UCVA:
Pre-op: 20/60 (33%)
03/08/2012: 20/20 (100%)

[liam82]

I wish I understood maths and figures!

[Peter Goren]

Hi Liam,

No problem. Here is a great introduction to eye optics: http://www.ophthobook.com/videos/eye-optics-lecture:
An explanation of cornea's refractive power starts at minute 5.

The images I posted were all taken by the Tomey TMS IV Topography Mapping System. The colored maps show the diopter values across the entire cornea and represent the surface structure. The average refractive power of the cornea is approximately 43 diopters. The cornea accounts for about 2/3 of the total optical power and together with the lens works to focus light on the retina. For keratoconus patients the cornea gradually steepens. As the cornea steepens the refractive power increases and that is seen by increasing diopter values. The color scale on the bottom shows increasing diopter values from left to right.

Simply put, red and pink areas are most affected by keratoconus. Blue, green, and yellow are the colors we would like to see instead. The goal of the surgery is to flatten the cone so that the diopter values obtained are closer to the average of 43.
Let me know if you have any other questions.

Regards,

Dr. Goren

[longhoc]

Hi Dr. Goren

Firstly, many thanks for providing us all with this new information on what seems a little-known (certainly here in the UK) method of assisting with the treatment of Keratoconus.

Most people if they are familiar with Radial keratotomy (RK) would have heard of it in a context of the famous -- perhaps that should be notorious ! -- Radial keratotomy "production lines" which were established to routinely treat Myopia/Hyperopia (a.k.a. short- and long-sightedness) in the Soviet-era USSR. The prevalence of side-effects from this procedure as it was then performed has perhaps given it an undeserved bad reputation. That, and the emergence of LASIK/LASEK and related procedures have definitely marginalised it -- that statement is certainly true for the UK and US although maybe it's less the case for Europe ?

As you rightly say, for Keratoconus patients, RK was always thought to be avoided at all costs. Indeed,

a) the difficulty of ensuring that a diagnosis of Keratoconus wasn't inadvertently missed especially in the absence of effective corneal topography equipment or;
b) for patients which had Keratoconus sub-clinically and couldn't be picked up at all prior to undergoing RK

these -- and other factors not related to Keratoconus -- added to the general falling-out-of-fashion for RK.

My big question is, for Keratoconus patients who are left with unsatisfactory vision post-Crosslinking or post-PK/DALK, what advantages does RK have as opposed to, say, LASIK or similar ? Here in the UK, a patient presenting this scenario would definitely be offered LASIK -- or possibly toric ICLs or Intacs as an alternative. Where greater degrees of correction are necessary, wedge resections are typically performed. Given the preference by clinicians here for those more established procedures, does your research lead you to believe that RK would give better outcomes ?

Another thing that would be very interesting is, are the techniques you're developing for RK improving the consistency of the resultant post-surgical epithelial plugs ? If the variability of these -- one of the main drawbacks of traditional RK -- could be reduced, then the predictability of the procedure would I guess be greatly enhanced.

Thanks again for all the interesting information you're providing us with !

Best wishes

Chris

[Peter Goren]

Hi Chris,

When my father-in-law, Dr. Artsybashev, began working at the Fyodorov Microsurgery Complex in 1984 only about 20 surgeons out of hundreds at the clinic were authorized to perform diamond knife procedures. He spent almost a year as an assistant and practicing on porcine corneas in the laboratory before his first real case. Following this first surgery a committee led by Dr. Fyodorov analyzed the results to determine if he should be allowed to continue his training. Radial keratotomy is a delicate procedure and results depend on the training and experience of the surgeon. Surgeons at the Fyodorov Complex unable to produce consistent results without complications were either quickly transferred to another department or sent back to the laboratory for months of practice.

As radial keratotomy gained popularity, a number of surgeons around the world attempted to replicate these results without proper training programs in place. The result was a tremendous number of complications for patients. Dr. Artsybashev feels strongly that the vast majority of surgeons should never have been allowed to perform diamond knife procedures. When I showed him some videos of radial keratotomy procedures performed in the United States and elsewhere on youtube, his immediate response was that those surgeries are extremely rough with improper techniques. It is no surprise that a number of those patients are experiencing terrible side effects and fluctuating vision.

In 1986, Dr. Artsybashev modified Fyodorov's technique and began operating on keratoconus patients. Those patients were unable to be corrected with spectacles or contact lenses and had no other option besides a corneal transplant. Dr. Artsybashev was the only surgeon granted permission to perform this experimental work as radial keratotomy was not a generally approved procedure for keratoconus. An extremely delicate technique is required for keratoconus patients and results without proper training would be horrendous. Furthermore, even after proper training, Dr. Artsybashev feels strongly that thousands of practice operations should be performed correctly before surgeons are granted permission for even early stage keratoconus cases. Performing radial keratotomy operations properly without complications (perforations, epithelial plugs, etc) has resulted in far superior statistics and outcomes for patients according to ongoing research at the clinic.

Dr. Artsybashev has been able to operate to improve visual acuity or stop progression when patients did not receive satisfactory results from CXl, Intacs, tPRK, PKP, and other procedures. I have not heard of keratoconus patients undergoing Lasik to treat their condition, but I assume you are referring to CXL combined with limited tPRK laser surgery. Laser surgery was also considered contraindicated for keratoconus, however, limited tPRK is now showing some great results. However, even limited tPRK will remove about 50 microns of corneal tissue. Therefore, an accurate measurement of the corneal thickness prior to surgery is essential to determine proper candidates. I hope this has answered most of your questions.

Regards,

Dr. Goren

[longhoc]

Hi again Dr. Goren

Sincere thanks for providing such detailed information. And do forgive my layman's ignorance -- I lack any kind of professional training (and it shows !) so I wrongheadedly thought that Advanced Topography Guided (T-CAT) laser treatment was sort-of like LASIK hence my lumping what is obviously two different procedures together. From what you've told us, the indications for RK are similar to that of T-CAT -- patients who have had crosslinking or perhaps a graft and yet are unable to get satisfactory vision with glasses or contact lenses of one sort of another. If I may be permitted a colloquialism for the benefit of us non-specialists, it is a "last throw of the dice" for those of us who might be facing the prospect of needing a graft even after crosslinking (or a re-graft following one which has resulted in a completely trashed topography which is basically uncorrectable by any conventional method). Do please let me know if my attempts to simplify this has made it factually wrong.

It would also seem that RK would be indicated where "reversable" methods had been tried but unsuccessful.

So, someone in the following position should consider RK:

Post-crosslinking or post-graft non-progressive Keratoconus patient who
- is unable to achieve satisfactory vision with glasses or contact lenses
- has already been fitted with an intra ocular lens or Intacs, unsuccessfully
- has already had or is considering laser treatment

Speaking from a personal opinion, it would probably be outside the skills of a non-professional Keratoconus patient to conclude whether or not RK was indicated for them. If they wanted to investigate this option further, I'd guess that they might wish to discuss it with the ophthalmologist who is treating them and knows their case well. Would either yourself or Dr. Artsybashev be amenable to being contacted by ophthalmologists in the UK who might want to respond to a patient enquiry ?

Thanks again

Chris