Eyeworld

SEPTEMBER 2023 | EYEWORLD | 69 G conductivity of fluid through the vitreous, and past suggestions that it results from "misdirected" aqueous are not consistent with physiological principles. When malignant glaucoma can occur There are a few clinical scenarios in which malignant glaucoma is more likely to occur. Dr. Schlenker said the most profound precipitating event is shallowing of the anterior chamber, for instance after filtering surgery, such as a trabeculectomy or tube shunt surgery in at-risk eyes. He said that any manipulation in the eye, even phacoemulsification, depending on other risk factors, can also result in malignant glau- coma. Female patients are more likely to have this occur, as are eyes with a small anterior chamber and a small axial length, according to Dr. Schlenker. He added that there is mounting evidence that zonulopathy is a risk factor for malignant glaucoma. Dr. Varma said there is a risk for malignant glaucoma, in certain eyes, when anterior cham- ber shallowing occurs, for instance when you're changing instruments in and out of the eye. "It causes the choroid to swell, and in a small eye, there is not much space for that swelling, so it pushes everything forward," he said. "In a small eye, the normal mechanisms to reset, to balance between the front chamber and the back chamber, don't work as well, so you end up unable to reverse it. The eye can't recalibrate, and it progressively pushes every- thing forward. The back chamber and the front chamber get out of balance." The physicians said that malignant glauco- ma can occur intraoperatively or can develop over time postoperatively. Postoperatively, Dr. Varma said the lens will start to shift forward. "At day 1 the patient could look good, but at week 1 they're a –1 or –1.5 myope because the lens has shifted forward, then they could be –3 or –4 by the end of the month; … they come back unhappy because now they're nearsighted even more. Progressive myopia is not an IOL calculation problem; one needs to look deeper," Dr. Varma said. Inas Aboobakar, MD, told EyeWorld that malignant glaucoma classically occurs in the early postop period after incisional glaucoma surgery in eyes with a history of angle closure, but she added that it can also be seen in predis- posed eyes after cataract surgery, iridotomy, or when starting miotic therapy. How to manage malignant glaucoma If you see the chamber shallowing intraoper- atively, the first thing to do is determine the cause. Dr. Schlenker said chamber shallowing that is not the result of malignant glaucoma includes leaky wounds, true fluid misdirec- tion through impaired zonules to the posterior chamber, or a suprachoroidal hemorrhage. If the chamber is shallowing, one must address the underlying cause immediately. Check the wounds, and maintain the anterior chamber as much as possible. If the red reflex is dimmed and the fundus exam reveals evidence of a su- prachoroidal hemorrhage, he would suture the wounds, form the anterior chamber, and defer any further surgery. If the problem is truly ma- lignant glaucoma, you must consider doing an irido-zonulo-hyaloidotomy. "You need to create a conduit from the back of the eye to the front of the eye to establish an equilibrium; eliminate this pressure gradient between the front and the back of the eye. I usually do an anterior vitrec- tomy where I'll do an anterior approach, unless the chamber is so profoundly shallow where I'd have to do a pars plana approach," he said. If malignant glaucoma develops postop, Dr. Varma said he'll most often take the patient back to the OR and use the vitreous cutter, but he added that you could do a YAG laser iridoto- my, going through the zonules and the hyaloid. Then you can go in with viscoelastic and push the lens back manually. Dr. Varma published a paper on the management of malignant glau- coma after cataract surgery, describing these techniques, in 2014. 3 Dr. Schlenker said if malignant glaucoma occurs postop, he will start with atropine and likely aqueous suppression. This pulls the lens backward, and in some cases, if the patient continued on page 70 References 1. von Graefe A. Beitrage zur pathologie und therapie des glaucoms. Archiv fur Ophthal- mologie. 1869;15:108–252. 2. Quigley HA. Angle-closure glaucoma—simpler answers to complex mechanisms: LXVI Edward Jackson Memo- rial Lecture. Am J Ophthalmol. 2009;148:657–669. 3. Varma DK, et al. Malignant glaucoma after cataract surgery. J Cataract Refract Surg. 2014;40:1843–1849.

• Blank Page