July 2018

COVER FEATURE

Challenging cases
Dealing with challenging cases in corneal surgery


by Ellen Stodola EyeWorld Senior Staff Writer and Digital Editor




Pseudophakic bullous keratopathy managed with the triple procedure of glued IOL, single-pass four-throw pupilloplasty, and PDEK. The left photo is preop and the right is 45 days postop.
Source: Amar Agarwal, MD


Sometimes surgeons face particularly challenging cases where specific technology or techniques need to be utilized. Amar Agarwal, MD, Chennai, India, and Clara Chan, MD, Toronto, Canada, discussed how they tackle some of their challenging cornea cases.

Severe ocular surface disease and associated limbal stem cell deficiency

Dr. Chan finds the most challenging patients she encounters are those with severe ocular surface disease and associated limbal stem cell deficiency. She said patients with Stevens-Johnson syndrome, graft-versus-host disease, and ocular cicatricial pemphigoid are particularly difficult. “These are patients who cannot be cured with a simple DMEK,” she said.
Dr. Chan said what makes these cases particularly challenging is that “there is no magic bullet cure.” The medical therapies to optimize the ocular surface and severe dry eye are often not covered by insurance, and often the patients are lower income or on long-term disability and unable to afford many of the treatments. “Surgical options like a stem cell transplant or a keratoprosthesis for these patients are high risk, and the prognosis is often very guarded even in the best cases,” she said. “Even on maximal treatment, patients are still symptomatic with varying degrees of dry eye, decreased vision, and eye pain.” Dr. Chan said that there’s also a high proportion of monocular patients with these ocular diagnoses, so there’s additional pressure on the physician. 
Dr. Chan has several steps for managing these cases, and she pointed out that rehabilitation can take months to years. She advocated a step-wise approach. First, she stressed the importance of optimization of patients’ severe dry eye. Next, she said to do oculoplastics repair of any eyelid deformities, lagophthalmos, or lash trauma issues. Physicians should do glaucoma management via a tube shunt or cyclophotocoagulation since glaucoma drops are toxic to the already compromised ocular surface. The last step is surgical intervention to rehabilitate their corneal blindness.
“In a young patient with no general health issues, a stem cell transplant with systemic immunosuppression would be my first choice, [but] in an older patient with multiple medical comorbidities, a Boston type 1 keratoprosthesis would be my first choice,” Dr. Chan said.
Dr. Chan added that collaborating with good optometrists with expertise in fitting modern scleral lenses has helped these patients immensely and allowed some to defer surgery. “Collaborating with a medical transplant team of specialists has also helped me to successfully perform ocular surface stem cell transplants to rehabilitate those with severe limbal stem cell deficiency,” she said. “Those undergoing stem cell transplants from a cadaver donor or a living donor require systemic immunosuppression and monitoring for potential side effects. Having the assistance of a medical transplant internist allows me to focus on the ocular surgery aspects of the patient’s care.”
Dr. Chan noted that the titanium backplate KPro has been shown in studies to have a lower rate of corneal melt, which is helpful in patients with a poor ocular surface who are at high risk for melt. 
She also mentioned new treatments that could help such patients. In cases of acute Stevens-Johnson syndrome, amniotic membrane should be placed across the lids, fornices, conjunctiva, and corneal surfaces along with a symblepharon ring in the acute phase of the disease as this can prevent much of the late stage sequelae that is such a challenge to manage later on, Dr. Chan said. “There are a variety of novel keratoprostheses in development across the world that may have fewer complications,” she said. Additionally, cultivated limbal stem cell therapy is expensive and challenging to replicate, but she thinks this technology will be better utilized in the near future. 

Pseudophakic bullous keratopathy

According to Dr. Agarwal, some of the toughest cases to handle are those with pseudophakic bullous keratopathy with a bad cornea. He deals with this frequently and uses a specific management technique. The reason this is hard to treat is because once a complication has occurred during cataract surgery, there is a vicious cycle of vitreous prolapse. Corneal decompensation, once started, becomes a nightmare, Dr. Agarwal said. The issue then is that the patient’s vision decreases, but a bigger problem stems from the corneal decompensation, which creates discomfort, and finally scarring of the cornea starts.
“Visualization for the surgeon is also badly affected,” Dr. Agarwal said. “The problem in handling these cases is that we have to do multiple procedures at one time.” The IOL has to be fixed, vitrectomy done, and the cornea replaced.
Dr. Agarwal’s technique is to do a glued IOL, a single-pass four-throw pupilloplasty, and pre-Descemet’s endothelial keratoplasty (PDEK).
For the glued IOL, Dr. Agarwal said the first step is to check the IOL. The patient may be aphakic or the IOL decentered or an AC IOL implanted. If it is an AC IOL that should be explanted and if a three-piece IOL is subluxated in the eye, the same IOL can be refixed with the glued IOL technique. This has now compartmentalized the eye into the anterior and posterior segment. If the existing IOL is in a good position, it can be left behind.
The second part of his management strategy is to do a single-pass four-throw pupilloplasty. The idea here is a closed angle secondary glaucoma that gets corrected as the angles are opened. “Also, we prevent the air, which will be put into the eye later on, from going behind the IOL,” he said. The single-pass four-throw pupilloplasty is a simple technique of repositioning the iris structure and pupil reconstruction, which entails intertwining of thread around itself that acts as a lock mechanism and ensures non-loosening of the loop.
For this technique, one has to use a prolene suture. “A single pass of the 10-0 suture on a long arm needle is passed through the iris tissue followed by creation of a loop with four throws around it that slide inside the eye,” Dr. Agarwal said. “This creates a helical configuration that prevents the suture from opening up.” A knot consists of an initial approximating loop followed by a second throw of sutures that creates a securing loop. This technique employs the creation of only the initial approximating loop but is comprised of four throws, thereby creating an intertwining of sutures that has a self-locking mechanism and prevents loosening of the suture loop, Dr. Agarwal said.
The final step is PDEK. Dr. Agarwal said one of the advantages of the PDEK technique is that the graft can come from a donor of any age. “The youngest we have used is a 9-month-old donor,” he said. “This gives us the advantage of a better endothelial cell count from the donor.” The second advantage of PDEK is during surgery the physician can manipulate the graft easily.
These three techniques of glued IOL, single-pass four-throw pupilloplasty, and PDEK have changed the management of pseudophakic bullous keratopathy, Dr. Agarwal said. In aphakic eyes, a loss of bicamerality of the eye occurs that leads to posterior migration of the air bubble used for attaching the PDEK graft, he said. This increases the risk for a postoperative partial or total graft detachment, forward bowing of the iris, iris-graft touch, and graft dislocation into the vitreous, all of which can necessitate secondary procedures such as refloating, rebubbling, vitrectomy, and AC formation, which increases graft endothelial cell loss.
“An effective compartmentalization of the eye can be obtained through the glued IOL technique,” Dr. Agarwal said. “The glued IOL offers advantages of posterior chamber IOL placement, ease of centration, [and] scleral fixation, as well as stable and sturdy fixation without pseudophacodonesis.” For this reason, Dr. Agarwal said it’s his preferred technique when combining with PDEK.
“The reason why pupilloplasty is connected to PDEK is that in eyes without a capsule and endothelial damage, one performs a glued IOL procedure,” he said. The pupil might be distorted and mydriatic. “The air, when infused in the AC for the PDEK graft fixation, goes into the vitreous cavity postop,” Dr. Agarwal said. This creates absence of air in the AC in the immediate postop period. It is essential for the air to be in the AC to keep the PDEK graft attached.
The main purpose of the single-pass four-throw pupilloplasty is that once the pupil is made miotic, the air remains in the AC and does not migrate to the vitreous cavity, Dr. Agarwal said. This then helps the graft remain attached with a good air fill in the AC.

Editors’ note: Drs. Agarwal and Chan have no financial interests related to their comments.

Contact information

Agarwal: aehl19c@gmail.com
Chan: clara.chan@gmail.com

Dealing with challenging cases in corneal surgery Dealing with challenging cases in corneal surgery
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