June 01, 2007
5 min read

Proper patient selection is essential when turning to DSEK

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SAN DIEGO — For surgeons transitioning from penetrating keratoplasty to Descemet’s stripping endothelial keratoplasty, careful patient selection will maximize outcomes and patient satisfaction, according to Michael K. Nordlund, MD, PhD.

“When you’re transitioning to endothelial keratoplasty, you want to try to pick those patients who will … give time for the surgeon to develop some confidence and some skills and minimize complications,” Dr. Nordlund said during Cornea Day held before the American Society of Cataract and Refractive Surgery meeting here.

Whereas PK can be used for all forms of corneal disease, Descemet’s stripping endothelial keratoplasty (DSEK) is indicated only for patients with endothelial failure, he noted. Surgeons inexperienced in DSEK should explain this difference to their patients and only select those with the most flexible personalities, he said.

“I tell them that [DSEK] is going to be more work for them in the first few days after surgery,” he said.

Because DSEK involves putting an air bubble in the eye, patients must be physically and emotionally willing to be positioned during the procedure, he said. Patients should also preferably live close to the office because graft dislocation is a common complication requiring follow-up visits.

There are several anatomical factors to consider as well, Dr. Nordlund said. Larger eyes with deep anterior chambers are best for beginner surgeons, he noted.

“During the surgery, you’re going to take typically between an 8-mm and 9-mm graft and insert it into the anterior chamber and unfold it. You’re going to need between 3 mm to 4 mm to let it unfold for there to be room for that to happen,” he said.

Surgeons should select patients without anterior chamber IOLs, glaucoma tubes or peripheral anterior synechiae, as they can complicate the unfolding process. Corneal clarity is also necessary for visibility, Dr. Nordlund said. He noted that a good way to take pressure off the first few cases is to select patients with limited visual potential so that the focus is more on eliminating discomfort and less on getting optimal visual results.

The following are other highlights of cornea sessions from the ASCRS meeting. All of these items appeared first as daily coverage of the meeting on the OSNSuperSite.

Surgeon details how to diagnose, treat TASS

When treating patients suspected of having toxic anterior segment syndrome, physicians must first rule out infectious etiologies before beginning treatment, according to Nick Mamalis, MD.

Nick Mamalis

Several key factors differentiate toxic anterior segment syndrome (TASS), a non-infectious syndrome, from conditions with infectious etiologies, he said. Whereas infectious etiologies typically appear at 4 to 7 days postop, he said, TASS has an immediate onset of 12 to 24 hours after surgery. Furthermore, patients with infections usually experience pain, whereas patients with TASS typically present with no pain and a diffuse “limbus-to-limbus” corneal edema, Dr. Mamalis said.

Physicians must check for damage to the iris at the slit lamp and damage to the trabecular meshwork by gonioscopy. IOP must be tracked closely; typically, TASS patients present with a “deceptively low” IOP that shoots up once the inflammation dies down, he said.

Once a TASS case is confirmed, physicians should prescribe hourly drops of 1% prednisolone acetate while carefully monitoring IOP.

“The first day, you may start them on treatment and see them back 3 or 4 hours later. Certainly you want to see them every day for the first few days,” Dr. Mamalis said.

Mild cases of TASS usually clear within a couple of weeks, while moderate cases may take up to 3 to 6 weeks to clear, he said.

Severe cases can result in permanent corneal damage, permanent corneal edema, chronic inflammation and intractable glaucoma, Dr. Mamalis said. Damage to the iris sphincter can result in a permanently dilated pupil, he said.

In addition to treatment, physicians must also conduct a thorough review of what went into the patient’s eye, as well as review their operating room protocols and instrument cleaning protocols, Dr. Mamalis said.

“You want to find out exactly what went into the eye. Get the lot numbers and samples of everything that went in there,” he said. “Sit down with your staff and nurses and go over with them systematically to make sure what you think is going on is actually going on.”

Link between keratoconus and psychiatric disorders

Patients with keratoconus are significantly more likely to have mental disorders than patients without the condition, according to Armando Signorelli, MD.

“Over the course of the years of clinical and surgical follow-up of patients with keratoconus, we have observed that patients demonstrated peculiar behavior ranging from emotional instability to diagnostic schizophrenia,” Dr. Signorelli said. “We reviewed the literature and found isolated reports, some describing a keratoconus personality in patients, though without a more detailed statistical study.”

Dr. Signorelli and colleagues administered the adult psychiatric morbidity questionnaire, a widely used mental health survey, to 100 keratoconic patients and 100 nonkeratoconic controls. They found significantly more keratoconic patients had mental disorders: 35% vs. 22% of controls (P < .042),="" he="" said.="" significantly="" more="" keratoconic="" patients="" also="" had="" experienced="" aggression="" (46%),="" sadness="" (49%)="" and="" suicidal="" thoughts="" (19%),="" he="" added.="">

Additionally, the researchers found a significantly higher incidence of mental disorders among women with keratoconus, 48% compared with 25% of women in the control group (P = .037), Dr. Signorelli said.

“The construction of a more specific questionnaire would most likely identify the behaviors directly relative to keratoconus,” he said. Such research could lead to a “holistic view” of keratoconus patients, including multidisciplinary treatment and stronger, more consistent physician-family support, he noted.

Study: Equally smooth donor interface with microkeratome, manually dissected corneas

Microkeratome and manual lamellar dissection of donor corneas produce equivalent interface tissue for endothelial keratoplasty, according to Karen L. Hoar, MD.

“Corneal surgeons can feel confident they are producing a smooth donor cornea using either the microkeratome or manual technique of preparing for endothelial keratoplasty,” Dr. Hoar and colleagues said in their comparative study.

“We wanted to look at two questions: Does a microkeratome produce a significantly smoother donor stromal surface than can be achieved by manual dissection? And is there a difference between the experience of using either of the methods?” she said.

For the study, 10 pairs of donor corneas were prospectively randomly assigned between two surgeons with differing experience in lamellar surgery. Each pair was then randomly assigned to microkeratome or manual dissection, she said.

“The manual technique used a 350-µm incision and hand dissection, and the microkeratome used a fresh plate each time at a depth of 300 µm,” Dr. Hoar said.

After dissection, the smoothness of the stromal interface was evaluated with scanning electron microscopy and assigned a grade of 0 to 3, with 0 being extremely smooth, she said.

Dr. Hoar and colleagues found no significant difference in smoothness between corneas dissected with a microkeratome and corneas dissected manually. They found that surgeon experience produced a significant difference in the microkeratome corneas but not in the manually dissected corneas, she said.

Stromal keratoplasty offers surgical alternative

Stromal keratoplasty is a new surgical option for stromal pathologies that offers quick recovery of the epithelial surface, according to Cesar C. Carriazo, MD.

Dr. Carriazo reported outcomes for three patients who underwent the procedure for keratoconus.

“With stromal keratoplasty, we first create a disc, we use a laser to remove the stroma, we place the donor in position, and after that we replace the disc to its original position,” he said.

In all cases, surgeons created a 100-µm thick, 9.5-mm diameter corneal flap and performed a pachymetry-assisted ablation 8-mm in diameter.

Surgeons then placed an 8-mm donor graft stripped of endothelium and epithelium, and they sutured the graft and the flap in place.

The epithelial surface of the flap was preserved at 24 hours postop. Uncorrected visual acuity improved from 20/400 to 20/100 at 1 month postop. Best corrected visual acuity improved from 20/80 to 20/50.

Postop corneal thickness was 650-µm with 10% an overall loss of 10% of the endothelium cells.

Advancements in technology will allow surgeons to avoid the first step of removing a disc, Dr. Carriazo said.

“In the future, with a femtosecond laser, we can create a pocket and remove just the stroma and introduce a normal stroma,” Dr. Carriazo said.

A note from the editors:

To facilitate bringing news to readers rapidly, for OSN SuperSite articles and meeting wrap-up articles, OSN departs from its editorial policy and typically does not send these items out for source corrections.