Eyeworld

EW FEATURE 76 Complex cataract cases October 2015 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. by Ellen Stodola EyeWorld Staff Writer Preoperatively, for high axial hyperopes, Dr. Tipperman said it may be helpful to administer IV mannitol, and intraoperatively, liberal use of OVD can help deepen the chamber and assist with lysis of adhesions. "In extremely short eyes with very shallow chambers it may be helpful to perform a limited pars plana vitrectomy," he said. The shallow chamber and potential for positive pressure puts patients with a short eye at risk for significant iris prolapse. "It is helpful to create a longer than normal corneal incision to help avoid iris prolapse," Dr. Tipperman said. IOL calculation considerations Both the Wang-Koch adjustment and Holladay 1 formula have helped Dr. Allen with long axial length eyes. "IOL calculations in short eyes are more challenging due to the relative proximity of the IOL to the retina and the large impact a small nea and can potentially damage it more. Other issues with a short eye are increased risk of capsule rupture and risk of choroidal hemorrhage. In long eyes, you basically have the opposite, Dr. Devgan said. There is a lot more room to work, but sometimes there can be too deep of an anterior chamber, and that's usually seen when you get reverse pupillary block, he said. "The tissues are more thinned out and they can get this over deepening," he said. Additionally, access to the cataract is more challenging. The main compli- cation is retinal detachment. Special preoperative testing Dr. Allen thinks a careful preopera- tive retinal examination is import- ant to rule out occult retinal pathol- ogy in the extreme axial myope. "Any suspicious retinal findings should be referred out for possible prophylactic treatment and counsel- ing with a retinal specialist," he said. with cataract surgery," he said. Even small errors in axial length mea- surement 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 cham- ber deepening with typical intra- ocular 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 lido- caine 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 co- hesive viscoelastic may be favored in the small eye to better maintain the anterior chamber and flatten the an- terior 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 pre- vent IOP rise postoperatively. In short eyes, the primary issue is that they're crowded, said Uday Devgan, MD, Devgan Eye Surgery, Los Angeles. "You're in very close proximity to the corneal endothe- lium because the anterior chamber is so shallow," he said. There's less room for the surgeon to work, and the phaco energy is closer to the cor- Considerations in long and short eyes It's important to be aware of 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, Ophthal- mic Partners, Bala Cynwyd, Pa. High axial myopes are especial- ly 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 the 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 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

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