EyeWorld Asia-Pacific December 2020 Issue

EWAP DECEMBER 2020 31 SECONDARY FEATURE Yeo Tun Kuan, MD Consultant, Department of Ophthalmology Tan Tock Seng Hospital 11 Jalan Tan Tock Seng, Singapore 308433 tun_kuan_yeo@ttsh.com.sg ASIA-PACIFIC PERSPECTIVES I ris prolapse is a common complication during phacoemulsification. Causes are mainly intrinsic or iatrogenic. Some eyes are more predisposed to iris prolapse: (1) shallow anterior chamber, (2) poorly- dilating pupil, (3) intraoperative floppy iris syndrome (IFIS) associated with alpha-blockers, or (4) preoperative high intraocular pressure (IOP). Surgeon factors include a short corneal wound, inadequate pupillary dilation, overfilling of the anterior chamber with ophthalmic viscosurgical device (OVD), excessive pressure from the speculum, or inadvertent trauma to the iris during surgery. In general, I am more wary of eyes with shallow anterior chambers and poorly dilating pupils. The speculum should be opened sufficiently and not excessively. My preference is to perform surgery with a 2.2-mm incision with a longer corneal wound, inject intracameral epinephrine, and avoid injecting too much OVD. Iris prolapse is more common with excessive dispersive OVD as it tends to go under the iris and does not easily escape out of the corneal wound, unlike a cohesive OVD. For patients with preexisting high IOP such as phacomorphic glaucoma, I would administer intravenous mannitol prior to surgery. I do not routinely stop alpha-blockers for IFIS and prefer to use iris hooks rather than a Malyugin ring as they secure the iris in place in addition to expanding the pupil. During phacoemulsification, excessive iris movements should alert the surgeon to the presence of IFIS. Care must be taken at this point as inadvertent aspiration of the iris traumatizes its tissue, reduces tone, and further accentuates iris movements and attraction to the phacoemulsification needle. From my experience, newer phacoemulsification machines with active or adaptive fluidics improve chamber stability, reduce the amount of fluctuations in the anterior chamber, and decrease the likelihood of accidentally catching the iris. However, once a part of the iris is traumatized, it would be better to secure it with an iris hook to avoid further complications. With iris prolapse, it is usually not sufficient to just reposit the iris without identifying the cause. The main culprit is commonly excessive OVD which should be released before repositing the iris. However, it is also imperative to exclude more sinister causes such as aqueous misdirection or suprachoroidal hemorrhage. At the end of surgery, I would induce miosis to draw the iris away from the corneal wound and consider a corneal suture if the risk of postoperative prolapse is high. Editors’ note: Dr. Yeo declared no conflicting interests. Direct illumination photo showing severe temporal iris trauma from intraoperative iris prolapse during cataract surgery. Higher magnification retroillumination photo of a patient with severe temporal iris trauma from intraoperative iris prolapse showing the edge of the optic and opacified peripheral capsule are visible behind the iris defect. The patient had severe light and glare sensitivity under all lighting conditions. Source (all): Kevin Miller, MD Dr. Mahendra said preoperatively to be aware of alpha blockers in the medical history and discontinue them ahead of surgery, prescribe atropine and reduce IOP. “However, tamsulosin and other alpha blockers have long half-lives and remain in the anterior chamber as long as 28 days. Also, alpha blockers cause ultrastructural changes in the iris stroma leading to its functional loss even after discontinuation of the drug,” Dr. Mahendra said. Intraoperatively, Dr. Mahendra said a MICS technique should be used, with a long, watertight main incision and sideport. Intracameral epinephrine and viscomydriasis can be used to maintain an adequate pupil size