32 EWAP DECEMBER 2022 GLAUCOMA continued on page 34 IOP elevation is becoming persistent, as they will be best able to assess whether a patient requires surgical intervention. “Fortunately, of the millions of intravitreal injections given each year, only a very small proportion of patients will require a glaucoma procedure as a direct result of injections.” When IOP spikes occur Dr. Kahook said that IOP spikes post-anti-VEGF injections come in two forms. “The first is an acute rise that happens in the majority of patients and is related to the expansion of volume within the eye and necessitates time for the eye to reequilibrate,” he said. This can be seen in both healthy and glaucomatous eyes, but it takes longer for eyes with glaucoma to reequilibrate given the compromised aqueous outflow channels. “The second form of IOP elevation is chronic and can be seen after one or more injections and can last for weeks to months or longer if not treated with medications or surgical intervention,” Dr. Kahook said, adding that it is this second form that results in higher rates of morbidity if not diagnosed and addressed. “This is also the reason that I advocate for making IOP checks part of the routine injection clinic workup before each injection takes place.” Dr. Weng said spikes are not uncommon immediately following the injection but usually will return to baseline within 30–60 minutes. What is less understood are the late-onset IOP spikes that can occur months or even years after a cumulative number of injections. “With intravitreal steroid injections, you can also see a subacute IOP spike in about one-third of patients that typically occurs 4–6 weeks following the injection, which is why I bring these patients back in that timeframe to check their IOP,” she said. What to do after an IOP spike A post-injection IOP elevation will typically resolve on its own within an hour, Dr. Weng reiterated, but if it persists with an IOP >35 mm Hg after a reasonable wait time in the office, she’ll start an IOP-lowering drop and see that patient back again in a few days. If it persists with an IOP >35 mm Hg and the patient has pain or corneal edema due to the elevated IOP, she will consider performing an anterior chamber paracentesis and discharge the patient on Aditya Sudhalkar, MD Consultant, Sudhalkar Eye Hospital Baroda, Gujarat, India adityasudhalkar@yahoo.com ASIA-PACIFIC PERSPECTIVES W e agree in principle with the concerns elucidated by Drs. Kahook, Mandava, and Weng. Intravitreal injections do cause a rise in IOP in the short term and in the long term. The short-term IOP rise is related to the immediate rise in ocular volume and has been suggested as a more potent risk factor for retinal nerve fiber layer (RNFL) thinning.1 Our own study2 demonstrates that adequate preoperative and intraoperative IOP care helps avoid RNFL thinning. The short-term IOP rise post injection, however, becomes a concern in patients who manifest IOP rise in the long term. These patients often have no light perception intraoperatively during and after the intravitreal injection procedure and often need paracentesis to restore retinal perfusion. Light perception needs to be confirmed on table prior to patient discharge. Vitreous reflux after injection reduces the chances of IOP rise on table.3 Long-term IOP rise has been typically noted in our experience in patients who have received six or more intravitreal injections over any period of time.2 As already stated, microdegradation products related to the molecule probably clog the trabecular meshwork, thereby leading to IOP rise. Also, IOP rise appears to be more of a concern in patients with age related macular degeneration (AMD) and probably represents an overall degenerative process affecting all ocular structures.2 The intravitreal dexamethasone implant may cause a lowering of IOP on table due to greater vitreous reflux and typically long-term rise with the implant is seen 45–65 days after the injection procedure.4 This is not the case with triamcinolone acetonide and it can cause both short-term and long-term rise in IOP. Indeed, IOP rise with the implant is not sustained in our experience4 and typically settles within 6 months. Contrary to this, triamcinolone acetonide-induced IOP rise is often sustained over months or years, sometimes necessitating incisional surgery for glaucoma. Switching from anti-VEGF injections to the dexamethasone implant does not necessarily increase the patient risk for further rise in IOP.4 As already stated, more studies are necessary to study the detrimental effects of IOP rise in the long term. References 1. Martinez-De-La-Casa JM, et al. Retinal nerve fiber layer thickness changes in patients with age-related macular degeneration treated with intravitreal ranibizumab. Investigative Opthalmology & Visual Science. 2012;53(10):6214–6218. 2. Bilgic A, et al. Sustained Intraocular Pressure Rise after the Treat and Extend Regimen at 3 Years: Aflibercept versus Ranibizumab. J Ophthalmol. 2020 Jan 20;2020:7462098. 3. Carnota-Méndez P, et al. Effect of prophylactic medication and influence of vitreous reflux in pressure rise after intravitreal injections of anti-VEGF drugs. European Journal of Ophthalmology. 2014;24(5):771–777. 4. Sudhalkar A, et al. INTRAOCULAR DEXAMETHASONE IMPLANT POSITION IN SITU AND OCULAR HYPERTENSION. Retina. 2018 Dec;38(12):2343–2349. Editors’ note: Dr. Sudhalkar declared no relevant financial interests.
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