June-July 2020

IN FOCUS

Ocular Surface Considerations For Surgery
Ocular considerations prior to keratoplasty


by Ellen Stodola Editorial Co-Director


Severe anterior blepharitis

Moderate epithelial basement dystrophy with subepithelial fibrosis

Fluorescein staining demonstrating severe superficial punctate keratopathy

Moderately elevated Salzmann’s nodular degeneration; the brown iron line indicates chronicity
Source (all): Christopher Rapuano, MD

A Salzmann’s nodule in the setting of Fuchs corneal endothelial dystrophy; the surgical plan will be to do a lamellar keratectomy at the time of the EK procedure

Patient with MRSA corneal ulcer from infected bullae in the setting of severe corneal edema and Fuchs corneal endothelial dystrophy; the residual scar measured 65% of the cornea centrally so the decision to do an EK was changed to a PK given corneal disease in all layers of the cornea
Source (all): W. Barry Lee, MD

 

Anytime you’re going to do a corneal transplant, EK or PK, there are a few important considerations, according to Deepinder Dhaliwal, MD. One is you have to know whether the cornea is neurotrophic. Sometimes the cornea is scarred and hazy, Dr. Dhaliwal said, referencing a case where the patient had an epithelial defect that she initially thought was ruptured bullae. Dr. Dhaliwal performed an urgent transplant but had issues because the eye was inflamed from an ulcer. She tried to do a DMEK but couldn’t get the graft to unfold due to a severe fibrinous reaction in the anterior chamber intraoperatively, so she performed DSAEK at a later date. Dr. Dhaliwal stressed the importance of a quiet eye for DMEK.
For this particular patient, Dr. Dhaliwal said she didn’t check corneal sensation ahead of time. Postoperatively, corneal sensation was reduced. This was when she realized the patient had Fuchs, neurotrophic keratitis, and a resolved infectious keratitis. The patient had been referred to her as “needing a transplant right away,” but Dr. Dhaliwal advised not operating on an actively inflamed eye if it can be avoided.

Scarring, defects, and surface abnormalities

When deciding between EK and PK, how much anterior corneal scarring there is matters, said Christopher Rapuano, MD. With EK, you’re replacing the back layers of the cornea. Chronic corneal swelling can cause some epithelial haze or anterior scarring, so a lot of patients who’ve had edema for a long time can have some scarring.
“If it’s mild, we usually go ahead with an EK because while mild scarring might decrease vision somewhat, overall, you’re better off than with a PK,” Dr. Rapuano said. “Sometimes postoperatively when swelling goes away, that scarring may improve over 3–6 months.” Even if some of the scarring doesn’t go away, it may be treatable with excimer laser PTK.
In dealing with severe/deep scarring plus corneal edema, Dr. Rapuano often goes straight to PK.
For other surface problems like Salzmann’s nodules, epithelial basement membrane dystrophy (EBMD), or other surface irregularities, it doesn’t matter for PK because you’re cutting it all out, he said. But for EK, you’re removing the back layer, so anything left on the front can still affect vision.
Assuming the patient has significant ocular surface irregularities, Dr. Rapuano said there are a couple of ways to handle this. “You can treat it prior to the EK, in the office or with an excimer laser PTK, to try to get the cornea as smooth as possible and then do EK,” he said. This would be especially important if doing combined EK and cataract surgery because the cornea needs to be as smooth and regular as possible for optimal calculations for cataract surgery.
If the patient already had cataract surgery and there are lumps and bumps, you can treat beforehand or go in for EK. Doing a superficial keratectomy at the time of EK and scraping off irregularities often works well, he said.
“When I see a lot of subepithelial fibrosis, basement membrane dystrophy, corneal haze, it doesn’t bother me because I can do a superficial keratectomy intraoperatively,” Dr. Dhaliwal said, adding that she tries to separate cataract surgery and corneal transplants if she can rather than combining the procedures. Generally, she will address whichever condition is more serious first. “If they need both, I like to separate and stage the two procedures,” she said, adding that the keratometry can be significantly off in these patients when you’re doing combined surgery. If they have a lot of scarring, haze, and bullae, Dr. Dhaliwal will use the Ks from the other eye if doing the cataract surgery first. When doing a transplant first, she will get new Ks after the cornea becomes clear and compact and the surface becomes smooth.
Dr. Dhaliwal uses a bandage contact lens in these patients postoperatively. If the patient is neurotrophic, amniotic membrane may help, and she also likes to use collagen shields soaked in an antibiotic.
W. Barry Lee, MD, said he addresses Salzmann’s nodules at the same time as the EK. “I perform a lamellar keratectomy with a Tooke corneal knife, place topical mitomycin-C 0.02% onto the central cornea with a sponge for 30–60 seconds, rinse with two bottles of balanced salt solution, then start my EK,” he said. “I put these patients in a therapeutic bandage lens after I have managed the air bubble, which typically occurs during a check 1 hour after surgery.”
For subepithelial scarring, he always evaluates the depth of the scarring at the slit lamp. If it is truly subepithelial, he uses superficial keratectomy at the time of EK. If the scar extends into the stroma, he uses anterior segment OCT to help determine whether PTK would be beneficial or whether a full thickness transplant should be considered.

OSD, dry eye, blepharitis, and glaucoma drop toxicity

Dry eyes and blepharitis often occur concurrently in these patients, so both diseases must be checked and adequately treated prior to EK, Dr. Lee said. “If tear deficiency is present, I start with preservative-free tears, topical cyclosporine, or lifitegrast,” he said. “Punctal plugs may be used as well, but I avoid these if concurrent blepharitis is present.” Dr. Lee prefers to start drops first and use plugs secondarily in cases without blepharitis, allowing inflammatory cells on the ocular surface to get better clearance via the puncta before surgery.
If glaucoma drop toxicity is present, he tries to get drops switched to preservative-free solutions prior to EK.
Dr. Dhaliwal stressed the importance of optimizing the surface. Often during EK, as you’re getting the graft to unfold, you can get corneal epithelial defects. It’s therefore important to optimize the ocular surface ahead of time to optimize healing postoperatively.
Dr. Dhaliwal said that optimizing the surface can include working on the lids and looking for Demodex or blepharitis. She likes to use tea tree oil wipes, which are available over the counter.
Dr. Dhaliwal also recommended a beaded mask, which is a way of getting the meibomian glands to clear. She’ll have patients use an artificial tear spray, which she said is well adopted by those who find it easier to use than getting a drop in the eye.
Dr. Dhaliwal uses anti-inflammatories to control dry eye and inflammation ahead of time, particularly topical cyclosporine or lifitegrast. But she added that it depends on the patient.
Dr. Rapuano said ocular surface disease, dry eye, and blepharitis may be less of a concern with EK than PK because you’re not disturbing the front layers of the cornea. He said you still want to maximize the health of the surface of the cornea, but PK will disturb it more than EK.
With PK, you want to make sure the surface is as healthy as possible. The transplant’s epithelial layer might be unhealthy or gone completely, which could result in a large or total corneal epithelial defect over the transplant. If you have a bad surface and still have to do PK, Dr. Rapuano said to maximize the surface health as best as possible. He also said to ask the eye bank for tissue that has an intact epithelium.
During surgery, he added that suturing or gluing amniotic membrane over the surface of the cornea can help, as can using a bandage contact lens or temporary tarsorrhaphy to suture the eyelids partially closed (laterally, so you can get a look in through nasal opening and patients can get medicine in). If dryness is an issue, you can also use punctal plugs, he said.

At a glance

• Superficial keratectomy can help a surgeon address some ocular irregularities prior to keratoplasty.
• Preservative-free tears, topical cyclosporine, or lifitegrast can help optimize the surface. Punctal plugs may be used as well. Surgeons also recommend tea tree oil wipes, beaded masks, and artificial tear spray.
• OSD, dry eye, and blepharitis may be less of a concern with EK than PK because you’re not disturbing the front layers of the cornea.

About the doctors

Deepinder Dhaliwal, MD
Director of Refractive Surgery
and the Cornea Service
UPMC Eye Center
Pittsburgh, Pennsylvania

W. Barry Lee, MD
Eye Consultants of Atlanta 
Atlanta, Georgia

Christopher Rapuano, MD
Chief of the Cornea Service
Wills Eye Hospital
Philadelphia, Pennsylvania

Relevant disclosures

Dhaliwal
: None
Lee: None
Rapuano: None

Contact

Dhaliwal: dhaliwaldk@upmc.edu
Lee: wblee@icloud.com
Rapuano: cjrapuano@willseye.org

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