GOOD OUTCOME

IOL calculation for patients with cataract and keratoconus can be challenging, but modern diagnostic technology, broadly customisable toric IOLs and the availability of new ways to adjust refraction postoperatively mean that patients have a good chance of a satisfactory visual outcome, said Tobias Neuhann MD, Marienplatz Eye Clinic, Munich, Germany. (See Figure 1.)

“Cataract surgery in the keratoconic eye must be customised in every case because every patient is different,†Dr Neuhann told the 17th ESCRS Winter Meeting. He noted that his own approach to keratoconic eyes first involves performing standard topography but also using a Pentacam Scheimpflug camera to create a Belin-Ambrosio map to identify the grade of ectasia. He and his associates also use the Pentacam and corneal OCT to determine whether the eye has undergone previous refractive surgery because patients sometimes forget. They also perform standard biometry and keratometry and endothelial cell counts because eyes with keratoconus are prone to Fuchs’ dystrophy. And last but not least, they perform a retinal OCT so that they can give patients a better idea of what sort of visual outcome they can expect.

Dr Neuhann noted that in cataract patients with keratoconus he performs phacoemulsification in his standard way, except that he uses a capsular tension ring in all cases. There is no increased risk of lens subluxation in such cases, but the capsular tension ring is useful because it makes the lens easier to replace if necessary. He added that it has yet to be determined how useful femtosecond laser-assisted cataract surgery will be in cataract patients with keratoconus.

Customisable refraction

Toric IOLs are suitable in most eyes with cataract and keratoconus, Dr Neuhann said. In Europe there are toric IOLs available which provide up to 20 D of toric correction. There are also add-on lenses available which, unlike the piggy-back lenses of old, sit in the sulcus, well-separated from the principal lens in the capsular bag. “The add-on lenses are very helpful and they are not calculated by biometry, they are calculated by the refraction. That means the patient tells you after the surgery what the power of supplementary IOL needs to be,†he said. (See Figure 2.)

He added that results with the Light Adjustable Lens (LAL®, Calhoun vision) have shown it to be very effective in the correction of up to 2.0 D of sphere and up to 3.0 D of cylinder postoperatively. In a series of 65 astigmatic eyes in which he and his associates implanted the lens, postoperative refractive adjustment reduced the cylinder from about 2.0 D to about 0.5 D in all cases. “I think the Light Adjustable Lens is the best device to correct astigmatism up to two or three dioptres. No other current method is as precise and it has demonstrated great safety, efficacy and stability. You can also make very predictable spherical correction with it, so you can get the refraction you really want,†Dr Neuhann said.