Surgeons weigh best method to treat corneal dystrophies
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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.
This month, Audrey R. Talley Rostov, MD, discusses lamellar keratectomy for corneal dystrophies, while William B. Trattler, MD, shares a PTK smoothing technique. We hope you enjoy the discussion.
Kenneth A. Beckman, MD, FACS
OSN CEDARS/ASPENS Debates Editor
Lamellar keratectomy
When I see patients with superficial corneal dystrophies, the first thing I do is identify the kind of dystrophy I am treating and how deep it is.
For example, for anterior basement membrane dystrophy, there is not much discussion about what treatment works best. In those cases, superficial keratectomy — removal of the epithelium — is the way to go. After removing the pathology within the epithelium, the epithelium can grow back smoother and without the pathological signs of the dystrophy.
There is more of a conversation when the dystrophy is deeper. I have treated cases of granular corneal dystrophy, which is a stromal dystrophy in which the opacities occur at different layers of the stroma.
Source: William B. Trattler, MD
In granular corneal dystrophy, there can be recurrent erosions, and in those cases, I have treated them with phototherapeutic keratectomy, which involves removing the epithelial layer just like in a superficial keratectomy. Then, light treatment with an excimer laser is used for sub-Bowman’s and recurrent erosions, and that works quite well. But in my personal experience, no matter what, the dystrophy comes back.
In cases of granular corneal dystrophy, I use corneal OCT to measure the corneal thickness and determine the location of the stromal opacities. Then, I make a femtosecond laser flap at sufficient depth to remove the bulk of the granular dystrophy opacities while preserving at least 300 µm of corneal tissue. I then excise the flap and place a bandage contact lens until the area has re-epithelialized. This is basically a lamellar keratectomy, but the corneal tissue is not replaced with donor tissue. This can only be done if there is adequate cornea left. If most of the opacity is in the anterior corneal stroma, this type of lamellar keratectomy can be performed and a cornea transplant can be delayed.
The patient is treated with steroids afterward, and this can be a nice technique for granular dystrophy or other anterior stromal opacities.
- For more information:
- Audrey R. Talley Rostov, MD, of Northwest Eye Surgeons in Seattle, can be reached at atalleyrostov@nweyes.com.
Smoothing PTK
In patients with granular corneal dystrophy, we see an irregularity in the anterior stromal surface that causes a decrease in quality of vision and best corrected visual acuity. This is quite visible when the epithelium is removed during phototherapeutic keratectomy (PTK) procedures.
There are several methods that can be considered for patients who are experiencing significant loss of BCVA due to granular dystrophy, including a corneal transplant, deep anterior lamellar keratoplasty or lamellar transplant. My preferred method is PTK.
The major challenge with visually significant corneal stromal dystrophies (granular/lattice/etc) is that no matter what surgeries are used, these conditions recur. With a corneal transplant, the cornea is cleared of that condition initially, but it returns over the next 5 to 10 years and causes the same visual problems. Transplants are therefore not a permanent solution. The patient then also has the risks that come with a corneal transplant.
Procedures such as DALK or lamellar keratectomy have fewer issues than transplants, but the stromal corneal dystrophy is still going to recur. Over the last 10 years, I have been performing a PTK procedure that is able to smooth the irregularities in the anterior stromal surface. The goal is not to remove all of the opacities, which often are located quite deep in the stroma. While a small amount of stromal tissue is removed with PTK, it is the smoothing of the anterior stromal surface that leads to the improvement in vision.
One thing to emphasize: The opacities are not the major issue affecting vision. These opacities extend all the way through the cornea, so a laser cannot get rid of them all. Focusing on smoothing the anterior stromal surface with minimizing the amount of corneal stromal tissue removed is the key, as this will leave the patient with a smooth anterior stromal surface and improved vision.
The procedure likely will have to be repeated about every 5 to 10 years, but because not much tissue is removed, there is plenty of room to repeat the procedure, and patients can do well.
- For more information:
- William B. Trattler, MD, of the Center for Excellence in Eye Care in Miami, can be reached at wtrattler@gmail.com.
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