New Research Data - DALK

[jayuk]

Hey

Just thought Id add this research (courtesy of PubM) which was released few weeks back relating to DALK and outcomes...

Good read, although the rejection finding kinda adds a new light to things....although all bar the Stem Cell failure, were reversed. It would be good to find out what kinda rejections they were......but it would appear that the DALK MAY NOT be rejectionless now!...time will tell...although a simple search on the web shows that a epith rejection has a extremely high rate of reversal when compared against an endothelial....which kinda confirms this finding


Jay

1: Cornea. 2007 Jan;26(1):59-64.Click here to read Links
Deep Anterior Lamellar Keratoplasty (DALK): visual outcome and complications for a heterogeneous group of corneal pathologies.

* Noble BA,
* Agrawal A,
* Collins C,
* Saldana M,
* Brogden PR,
* Zuberbuhler B.

Department of Ophthalmology Leeds Teaching Hospitals, NHS Trust Leeds General Infirmary, Leeds LS2 9NS, UK.

PURPOSE: To review the visual outcome and complications of deep anterior lamellar keratoplasty (DALK), using Melles technique. METHODS: All patients undergoing DALK between December 1999 and March 2005 were routinely entered into a longitudinal study. DALK was attempted in 80 eyes of 68 consecutive patients. Descemet membrane perforation occurred in 11 eyes, of which 7 required conversion to penetrating keratoplasty. The visual and refractive outcome of these eyes is presented separately. The mean follow-up was 21.2 months. Best-corrected visual acuities (BCVAs), refraction, graft clarity, and complications were recorded at each visit and analyzed. RESULTS: The mean patient age was 34.2 years. Keratoconus was the main indication for surgery (58 eyes), followed by herpes simplex keratitis (6 eyes), corneal stromal dystrophy (5 eyes), stem cell failure with scarring (2 eyes), corneal dermoid (1 eye), and corneal opacity (1 eye). The mean central corneal thickness changed from 0.42 +/- 0.07 mm preoperatively to 0.62 +/- 0.06 mm postoperatively. At latest follow-up, BCVA of 6/6 or better was present in 24.7%, 6/9 or better in 69.9%, and 6/12 or better in 84.9% of the eyes. The mean postoperative refractive cylinder was 3.31 +/- 2.59 D, and the mean spherical equivalent was -2.54 +/- 3.61 D; 52.2% of the eyes had a refractive cylinder less than +/-3 D and 49.3% of the eyes had a spherical equivalent less than +/-3 D. Rejection episodes occurred in 9.6% of the eyes but were successfully reversed in all eyes. Graft failure occurred in 1 eye with severe stem cell deficiency. CONCLUSION: This is the largest series of DALK cases using the Melles technique in a variety of corneal lesions. Our results confirm the usefulness and safety of this procedure in conditions with no endothelial involvement. Graft rejection remains a significant complication but is associated with good recovery because the endothelium is spared

[John Smith]

Thanks for posting this, Jay.

Do you know what the Melles technique referred to above is? Is it the "standard" DALK technique that many here have experienced, or is it the more unusual technique involving freeze-dried donor material that I had.

For those who don't know about my unusual graft - I have no epithelial or endothelial tissue from my donor. The visual recovery is very slow, but hopefully all will be worth it.

[jayuk]

My pleasure John

Melles Technique was created by Dr Melles and I beleive that majority of DALK operations are used with this technique or a slight variation...

I beleive the technique is around the instruments used...

http://www.dorc.nl/catalogus/lamkerset.html

HTH

J

[Andrew MacLean]

Jay

I am worried about the tail end comment. I had thought that rejection could be virtually discounted following a DALK. It seems, after all, that good news is no news.

Andrew

[jayuk]

I agree Andrew...I was a little shocked at reading that.

However, one thing Ill say is that the results were based over the period when DALK was first introduced....therefore its not known how many layers were removed, whether Epithelium was also transplanted or left, etc etc

It would be interesting to other Opthams opinions, Ill raise this with my own. Maybe John and You can also do the same?

J

[Andrew MacLean]

I was already planning to ask Doc Ramaesh next time I see him.

actually, between John and me I think we have covered all the epithelium possibilities: my graft had epithelium intact, his had none.

Andrew

[John Smith]

Actually, because of my freeze-dried DALK graft, I was told that "unlike a normal DALK", the rejection rate was "absolutely zero". Which of course implies a higher than zero risk for DALK.

But I must admit that I didn't think it was that high.

I must review John Dart's talk on the DVD. I'm sure he mentioned that bit; just before I fainted

[Anne Klepacz]

Thanks for a very interesting post Jay. I wonder whether one factor in the rejection rate is that the study looked at grafts done for a number of different reasons, not just KC. I seem to remember something from our first conference which suggested that the success rate for corneal grafts was highest for KC, with grafts done for other conditions sometimes being less successful. I don't know whether that was to do with rejection rates, but it would be interesting to know whether the rejection episodes in this study were spread evenly throughout all the different grafts. And even if it does turn out that the rejection risk for DALK is higher than we thought, it does sound as though rejections with DALKs are very easily reversed.
Anne

[Sajeev]

It is true Anne, for KC PK Transplants do better, I remember a Dr from Spain saying this when he posted this study below. So the newer methods must have milder rejection, by which easily reversable, or the amount is lower. Improvements are being made all the time.

Extended long-term outcomes of penetrating keratoplasty for keratoconus.



Pramanik S,

Musch DC,

Sutphin JE,

Farjo AA.


Cornea, External Diseases and Refractive Surgery Services, Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.



OBJECTIVE: To report graft survival results for initial penetrating keratoplasty (PK) performed more than 20 years ago for keratoconus. Secondary outcome measures included recurrent keratoconus, best spectacle-corrected visual acuity (BSCVA), and rates of glaucoma. DESIGN: Retrospective, consecutive, noncomparative case series.

PARTICIPANTS: All patients with clinical and histopathological keratoconus who underwent initial PK at the University of Iowa Hospitals and Clinics from 1970 to 1983. Patients with pellucid marginal degeneration were excluded.

METHODS: At baseline, age, preoperative BSCVA, keratometric astigmatism, and host/donor graft sizes for each eye were recorded. Visual acuity and intraocular pressure were followed until the eyes reached 1 of 4 end points: graft failure, recurrent keratoconus, loss to follow-up, or death. Kaplan-Meier survival analysis was performed to estimate the long-term probability of graft failure and recurrent keratoconus. RESULTS: Among the 112 eyes of 84 patients who met entry criteria, there was a mean age at transplant of 33.7 years and preoperative BSCVA of 20/193. With a mean follow-up of 13.8 years (range, 0.5-30.4), 7 eyes (6.3%) experienced graft failure. Recurrent keratoconus was confirmed clinically or histologically in 6 eyes (5.4%), with a mean time to recurrence of 17.9 years (range, 11-27). Kaplan-Meier analysis estimated a graft survival rate of 85.4% and a rate of recurrent keratoconus of 11.7% at 25 years after initial transplantation. Six eyes (5.4%) developed open-angle glaucoma, and 2 eyes required trabeculectomy. At the last follow-up visit, 82 eyes (73.2%) had BSCVA of 20/40 or better.

CONCLUSION: Penetrating keratoplasty offers good long-term visual rehabilitation for keratoconus. Relative to other indications for PK, there is a low rate of graft failure. Late recurrence of disease occurs with increasing frequency over time. Given the younger age at which keratoconus patients undergo corneal transplantation, these long-term findings should be incorporated into preoperative counseling.

[jayuk]

Anne

Correctios!...KC has the highest success rate for PK....it would be interesting to see the longer term results on the first study posted for DALK which is going to be very good reading.

Bear in mind also that DALKs are also used for superficial corneal damage....and Id assume this was also the case in the initial study; but that may incorrect for me to assume that!....but thats the only reason why I can see the rejection rate mentioned in the study...but we shall see in time I guess.....

But I do still think that the idea of having the DALK over the PK far exceeds the benefits...as you say...its alot easier reversing a rejection episode with a DALK then a PK.....and I guess if someone has advanced KC...they can limit the total risk of rejection across two eyes by having a PK and DALK....

J