All of us Vs Keratoconus


Members Login
Chatbox
Please log in to join the chat!
Post Info TOPIC: Opposite clear corneal incisions


Senior Member

Status: Offline
Posts: 122
Date: Sun Nov 27 6:00 AM, 2005
Opposite clear corneal incisions
Permalink   
 


Hi everyone.


I came across this website. http://www.roseneyeclinic.com/correction/refractive_surgery.html#occi_astig


They talk of a technique OCCI for astigmatisms.  The sentence "This can be primary astigmatism or secondary to previous eye surgery such as corneal grafts or eye problems such as keratoconus or pellucid marginal degeneration" caught my attention. Now I'm not entirly sure with all the 'or's in the above if they mean that it is used primarily for keratoconus or whether they mean for astigmatism after a transplant for keratoconus. I sent them a message through the contact section on their website, a couple of days ago but have not heard back yet.


Has anyone heard of this technique and its use for keratoconus? It would seem somewhat similar to mini-ark.


 


 



__________________


Executive

Status: Offline
Posts: 397
Date: Sun Nov 27 8:12 AM, 2005
Permalink   
 

Hello Chris,
Your findings here are of great interest to me... I have spent along time searching the net for articles that even remotely add substance to the principles that prof. Lombardi suggests. I have had limited success but this treatment you have found is very interesting...
I have found the following associated articles: The quotes from these sites sound very familar to me :)
article 1

'...we learned that the corneal meridian on which the extended incisions were based flattened during the healing process. Pathologically, large incisions heal with added tissue, with consequent extension of the radius of curvature of that central meridian.'

article 2

'... The operation is based on the very well known fact that any penetrating corneal wound of a certain length provokes permanent astigmatism. So we are using the provoked astigmatism to correct the pre-existing astigmatism,"

Paired opposite clear corneal incisions to correct preexisting astigmatism in cataract patients

Journal of Cataract & Refractive Surgery Volume 31, Issue 6 , June 2005, Pages 1167-1170

Fifteen eyes of 14 cataract patients with a mean age of 78.4 years 6.38 (SD) (range 69 to 90 years) were recruited for the study. Inclusion criterion was topographic astigmatism of more than 2 diopters (D) in the cataractous eye. Preoperative refraction, autokeratometry, and topography were performed. The steep axis was marked before sub-Tenon's anesthesia was given. Paired 3-step self-sealing opposite clear corneal incisions were made 1 mm anterior to limbus on the steep axis with a 3.2 mm keratome. One incision was used for standard phacoemulsification, and the other was left unused for astigmatic correction. All the patients had day-case surgery. The first follow-up was at 1 month. Postoperative topography, keratometry, and refraction were performed on all patients.
Results
Mean preoperative and postoperative topographic corneal astigmatism were 3.26 1.03 D (range 2.30 to 5.80 D) and 2.02 1.04 D (range 0.20 to 4.00 D), respectively. Mean astigmatic correction was 1.23 0.49 D (range 0.30 to 2.20 D). Mean surgically induced astigmatism by vector analysis was 2.10 0.79 D (range 0.80 to 3.36 D). There were no incision-related complications.
Conclusion
Paired opposite clear corneal incisions on the steep axis is a useful way to correct astigmatism in cataract patients, requiring no extra skill or instrumentation.

Let us know if you if you get a replie from the clinic using this method,
Regards,
Hari



__________________


Executive

Status: Offline
Posts: 437
Date: Fri Dec 2 6:25 PM, 2005
Permalink   
 

Very interesting! It would be also interesting to know what Dr. Lombardi thinks about it, for he should understand what it is.

__________________
yarsky


Newbie

Status: Offline
Posts: 1
Date: Sat Dec 3 10:00 AM, 2005
Permalink   
 

Surgical therapy: After numbing the patient's eye with anesthetic drops, the procedure can be completed within a few seconds. The procedure is safe and is not associated with glare or starburst, which often occurs with true corneal incisions (eg, RK, AK). Furthermore, the cornea is usually stable within a week, indicating that visual fluctuations have typically resolved by that time.

The forgiving nature of this procedure is because of the placement and the length of the incision. Placing the incision precisely on axis is not as critical because the incision is 9 mm in length. Since the incision produces less effect than CRIs, significant overcorrections are rare. The amount, the axis, and the symmetry of the corneal cylinder are determined by keratometry and topography. The refractive cylinder is also considered in phakic patients. The surgical keratometer is used to confirm results.

The globe is fixated with the modified Fine-Thornton ring, with a diamond blade placed just inside the limbus (see Image 7). The appropriate incision length is achieved by visually following the degree marks on the ring. A diamond blade should never be held against the side of the degree gauge because it causes damage to the blade and affects the quality of the incision.

LRIs are made using a micrometer knife (see Image 8). For most patients, a blade setting of 600 mm is used; however, a blade setting of 500 mm is recommended for patients older than 80 years and for those patients with corneoscleral thinning. LRIs are placed in the steep axis at the limbus, just anterior to the palisades of Vogt. A 6-mm incision is required for each diopter of astigmatism up to 2 D; to correct astigmatism between 2-3 D, LRIs of 8 mm in length are used. For astigmatism greater than 4 D, LRIs are combined with CRIs to attain adequate correction. LRIs are used to correct the first 4 D; the remaining astigmatism over 4 D is corrected by CRIs. Compared to older patients, younger patients require longer incisions to achieve the same effect.

Planning the strategy around corneal topography, keratometry, and surgical keratometry is always important. The same rules used for phakic patients apply to pseudophakic patients. However, the axis and the amount of astigmatism in pseudophakic patients are determined by refraction only. Topography is used to determine the symmetry of the astigmatism.



__________________


Executive

Status: Offline
Posts: 437
Date: Sun Dec 4 12:06 PM, 2005
Permalink   
 

Hi Bob101, thanks for an interesting link. This subject is extremely interesting. What I like is the capture "Surgical Therapy".
I think what is needed is a study, an academic study, with modern equipment, confocal microscopy, etc.etc.etc of these techniques, what happens in the eye, why scar collagen that is synthesised in the process of the corneal wound healing gives so much strengh to the cornea...
And what are the critical parameters of the KC cornea when incisions can still give an improvement?

__________________
yarsky


Senior Member

Status: Offline
Posts: 122
Date: Thu Dec 15 7:47 AM, 2005
Permalink   
 

Hi,


I have heard back. Basicly the surgeons have discussed my request and feel that the technique would weaken and already weak cornea so the answer is no with OCCI for keratconus or certainly with what I described as moderate keratoconus in my original email. I will point out however that when I initially made contact the optometrist that answered me back did not give a blanket 'no this is a contradiction to keratoconus' and also when I sent her an email after about a week with no reply asking what the situation was she said one of the doctors had said no but she wanted to ask another one. Prehaps, and I am only speculating here, we might see OCCI offered in the future as a treatment.


 



__________________


Executive

Status: Offline
Posts: 397
Date: Thu Dec 15 7:26 PM, 2005
Permalink   
 

Hi Chris,
Great to get a little more info about this technique.... Maybe it was just an oversight but it seems a little strange that they would initially mention this procedure in connection with KC and then decide later that it was a contridiction. But as I say this may have just been human error... will be interesting to see where this story leads,

Hari

__________________


Senior Member

Status: Offline
Posts: 122
Date: Fri Dec 16 3:52 AM, 2005
Permalink   
 

Hi Hari,


Yes those are my sentiments exactly. I think this will definately be one to watch.



__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.

Post to Digg Post to Del.icio.us

www.kcfreedom.org

Knowledge Works