EyeWorld Asia-Pacific December 2015 Issue

December 2015 22 EWAP FEATURE Considerations in long and short eyes by Ellen Stodola EyeWorld Staff Writer AT A GLANCE • In patients with long eyes, an acrylic lens may be the best option because the surgeon should consider the possibility of future retinal surgery. • Long eyes are at risk for reverse pupillary block. To prevent this, lower the bottle height or infusion pressure and use a second instrument. • In short eyes, even small errors in axial length measurement can result in larger IOL power errors than in highly myopic eyes. A small eye with a very shallow anterior chamber undergoing cataract surgery. This shows the technique of doing a 25-gauge pars plana anterior vitrectomy tap in order to deepen the anterior chamber. Source: Uday Devgan, MD When treating these patients, it’s important to be aware of special considerations and complications that can occur E xperts weighed in on major worries to be aware of in patients with long or short eyes, special considerations, and IOLs that may work particularly well. Key anatomic worries Cataract surgery in patients with extremes of axial length can be challenging for many reasons— and these reasons vary depending on if it is a long or short eye, said Richard Tipperman, MD , Ophthalmic Partners, Bala Cynwyd, Pa. High axial myopes are especially at risk for retinal detachment, and patients with axial myopia are a challenge to measure accurately with ultrasound A-scan because the fovea is often located on the side of a staphyloma rather than the bottom. “The majority of patients with high axial myopia will also have large anterior segments,” he said. “This results in a deeper than normal anterior chamber and alters the vector forces required to create a capsulorhexis.” For surgeons early in their learning curve, this can make the capsulorhexis creation more challenging. Some patients with large anterior segments may also have extraordinarily large capsular bag sizes. In these patients, there is the potential for spontaneous IOL rotation, Dr. Tipperman said. “Patients with high hyperopia, or short axial lengths, have their own set of challenges associated with cataract surgery,” he said. Even small errors in axial length measurement can result in larger IOL power errors than in highly myopic eyes. Optical biometry is ideal for measuring these patients, assuming that lens density does not preclude obtaining a valid measurement, he said. Short eyes also tend to have shallow chambers and may have posterior synechiae and peripheral anterior synechiae, Dr. Tipperman said. Meanwhile, Quentin Allen, MD , Florida Vision Institute, Stuart, Fla., said that long eyes typically have thinner, more flexible sclera. “This may in some cases mean a tendency toward corneal incisions that may not seal as well as more standard eyes.” The longer eyes are also predisposed to abnormal chamber deepening with typical intraocular infusion pressure that is not noted in normal eyes, also known as reverse pupillary block, he said. This can be prevented by lowering the bottle height or infusion pressure. “Using a second instrument, or the I/A tip, to gently elevate the edge of the iris away from the anterior lens capsule may be useful as well to relieve the reverse pupillary block,” Dr. Allen said. “Intracameral lidocaine may lessen the discomfort of reverse pupillary block, and its use is advised for eyes at risk for this phenomenon.” On the other hand, short eyes have more positive pressure and shallow anterior chambers with less room for surgical maneuvers. “A cohesive viscoelastic may be favored in the small eye to better maintain the anterior chamber and flatten the anterior capsule more than a dispersive viscoelastic, preventing the capsule from tearing out in this setting.” He recommended using a product like Healon 5 (Abbott Medical Optics, Abbott Park, Ill.), a super-cohesive viscoelastic, but he cautioned that surgeons need to be sure to remove the viscoelastic completely to prevent IOP rise postoperatively. In short eyes, the primary continued on page 24