This article is more than 5 years old. Information may no longer be current.
Surgeon recommends meticulous corneal examination before cataract surgery
Corneal dystrophy and degeneration can skew biometry and topography measurements and induce corneal astigmatism.
Click Here to Manage Email Alerts
Surgeons need to detect and treat corneal disease that may adversely affect visual and refractive outcomes after cataract surgery.
“These conditions are very easy to look for,” W. Barry Lee, MD, FACS, said at Hawaiian Eye 2013. “Sometimes we get very busy in our exams seeing patients and we’re just thinking about scheduling the cataract surgery and what lens to pick rather than focusing on the exam of the cornea. But just really focus on examining the cornea, and I think you will find these things really make a difference in your pre- and postoperative planning.”
Dry eye disease, blepharitis, corneal ectatic disorders, anterior and posterior corneal dystrophies, and corneal degenerative disease can induce corneal astigmatism and opacity and distort preoperative measurements, Lee said.
He suggested delaying cataract surgery to allow the corneal surface to stabilize after treatment.
“In considering treatments, I think a staged treatment option for many of these is very useful and can really help maximize your outcomes,” Lee said.
Corneal dystrophy, degenerative diseases
Epithelial basement membrane dystrophy (EBMD), the most common type of anterior corneal dystrophy, may obscure the visual axis, distort biometry and topography, and lead to inaccurate IOL calculations, Lee said.
“Obviously, the more deposits on the cornea, the more distortion you get and, unfortunately, the more inaccuracy we get with IOL calculations,” Lee said.
He recommended a staged procedure involving epithelial debridement followed by cataract surgery 4 to 6 weeks later. Biometry and topography should be repeated just before cataract surgery to ensure good outcomes, he said.
Corneal degenerative diseases, such as pterygium and Salzmann’s nodular degeneration, can induce astigmatism, as well.
“Induced astigmatism must be a main concern,” Lee said.
In addition, pterygium and Salzmann’s nodules can alter biometry and topography.
Salzmann’s nodules can be removed easily at the slit lamp or in a minor surgery suite. Lee said there is a need to repeat the topography measurement after the nodule has been removed.
Examining the cornea for signs of Fuchs’ endothelial dystrophy is essential because guttae of the cornea can obscure the visual axis, Lee said.
“I think making the diagnosis, just taking the extra time to go to high magnification on your slit lamp and look at the posterior endothelium, makes this diagnosis very easy, yet many people still miss it from getting in a hurry with the examination. Obviously, vision can be affected just simply by the guttae in the visual axis, much like the EBMD patients with visual axis deposits,” Lee said.
Blurred vision in the morning, dense guttae and increased corneal thickness may portend corneal decompensation, Lee said.
Patients with Fuchs’ dystrophy should be counseled about the potential need for Descemet’s stripping endothelial keratoplasty in the future.
Surgical technique, lens selection
Surgical technique is critical in cases involving corneal disease, Lee said.
“If I have a patient with small guttae, I might go to a scleral incision instead of a clear corneal incision,” he said. “You might want to think about using lower phaco settings and try to limit your irrigation. Obviously, it’s very important to use a dispersive viscoelastic and consider using multiple applications of that during your phaco technique. And, certainly, a phaco chopping technique will likely give you less phaco time than, say, a divide-and-conquer technique.”
IOL selection is key in patients with Fuchs’ dystrophy. DSEK may result in a refractive shift of 0.7 D to 1.5 D.
“This needs to be accounted for in your IOL calculations,” Lee said. “I’ll tend to aim for –1 D to –1.25 D for myopic predictive value.”
IOL opacification can also be problematic in cases of DSEK after previous cataract surgery.
“This has been described in eyes essentially with hydrophilic acrylic lenses,” Lee said. “It relates to a reaction with the air bubble in DSEK and the hydrophilic acrylic material to cause a hydroxyapatite deposition on the anterior IOL surface.”
Hydrophilic acrylic IOLs should be avoided in patients with guttae, just in case they need to undergo DSEK in the future, Lee said.
Multifocal IOLs should also be avoided in cases involving guttae of the cornea, he said.
“These are progressive conditions,” Lee said. “While the patient may see well for a while, they’re eventually going to progress, and you don’t want that multifocal IOL in the eye.”
Surgeons should also avoid using multifocal IOLs in eyes with very high regular astigmatism, any form of irregular corneal astigmatism including advanced pterygia, Salzmann’s nodules and severe dry eye. Prior refractive surgery is another potential avoidance for these IOLs, Lee said. – by Matt Hasson