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Managing IOP issues after cataract surgery
Retained OVD is the most common cause for increased IOP in the immediate postoperative period.
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It is recognized that cataract surgery can help lower IOP, likely due to the increased angle opening permitted by the thin IOL as compared with the much thicker cataractous lens. But there can be fluctuations in the IOP after cataract surgery, and these should be appropriately managed to provide the best postoperative course for our patients.
Pre-existing IOP issues
Patients with pre-existing forms of glaucoma are at a greater risk for postoperative IOP spikes. For those patients who use topical medications and have not had filtering glaucoma surgery, these pressure spikes tend to be more limited and transient. Patients can continue to use most of their topical medications in the perioperative period with the exception of prostaglandin analogues, which may make the eye more susceptible to inflammatory processes such as cystoid macular edema.
For those with prior glaucoma surgery such as trabeculectomy or external drainage tube placement, the viscoelastic used during cataract surgery can block the egress of fluid at these sites. Care must be taken to carefully aspirate all viscoelastic that is in proximity to these glaucoma surgical sites. During cataract surgery, fluid outflow via the glaucoma site can contribute to anterior chamber instability, so care should be taken to regulate the aspiration flow rate on the phaco machine to find balance (Figure 1). In a virgin eye, there are two areas of fluid outflow: the phaco probe and leakage from incisions. Patients with prior glaucoma surgery have an additional, third point of fluid egress, leading to potential instability because there is still the one source of inflow of balanced salt solution.
Source: Uday Devgan, MD
Risk factors for postop IOP rise
Patients with pre-existing glaucoma are more susceptible to postoperative increases in the IOP. Highly myopic patients can also have a tendency for increased IOP after an uneventful cataract surgery. Difficult cases that require extensive tissue handling and prolonged surgical times may also be more likely to have postoperative pressure issues. Intraoperative complications that result in posterior capsule rupture, vitreous prolapse and sulcus IOL placement have a higher risk for postop IOP spikes and even prolonged glaucoma issues. Patients with steroid-responsive glaucoma can have an exacerbation when receiving ocular steroids after cataract surgery.
Postop timing of IOP rise
Steroid-response IOP rise occurs about 10 days to 2 weeks after the start of steroid exposure. The best treatment is to taper or stop the topical steroid medications and use other agents such as NSAIDs to control any residual inflammation. The addition of topical IOP-lowering medications is also useful in these patients.
Increased IOP in the first day or two after cataract surgery is typically due to retained ophthalmic viscosurgical device (OVD) in the eye. Our dispersive agents adhere so well to tissues that sometimes our usual irrigation/aspiration probe fluidic and vacuum settings are insufficient to fully remove the viscoelastic. Leaving this viscoelastic will cause high pressure issues for many days after the cataract surgery as these large-chain molecules try to pass through the trabecular meshwork. These patients will benefit from postop topical and systemic pressure-lowering medications.
Preventing OVD-related IOP spikes
The best way to prevent increased IOP from retained OVD is to fully remove it from the eye at the end of the case. With the irrigation/aspiration probe, using a high flow setting of 50 cc per minute or higher, along with a high vacuum level of at least 500 mm Hg, will make OVD removal easier. In some cases, this is still not enough and there is retained OVD in the angle of the eye.
To remove the OVD from the angle of the eye, the angle sweep technique can be performed using balanced salt solution on a 27-gauge blunt cannula and a 3-cc syringe. This is forcefully irrigated toward the angle of the eye opposite the paracentesis, and a sweeping motion is done to wash out the OVD (Figure 2). This OVD can then be expressed through the paracentesis or the main incision with ease.
Because of the way that we inject the OVD via the paracentesis incision, it gets pushed with the most force into the opposite angle of the eye. This is the area that benefits most from the angle sweep technique (Figure 3). Try this technique at the end of your cataract cases to see just how much OVD is being left inside the eye.
Concomitant glaucoma and cataract surgery
We can also perform glaucoma procedures at the same time as cataract surgery to further aid our patients with glaucoma. This has become popular with MIGS devices that are placed to allow greater aqueous outflow via trabecular bypass or the suprachoroidal space. We can also perform larger glaucoma surgeries such as trabeculectomy or external drainage tube placement at the same sitting as cataract surgery. These patients may have fluctuations in the IOP, both high and low, after cataract surgery, which needs to be carefully monitored. In addition, certain surgical steps may be helpful such as making a smaller capsulorrhexis to securely hold the IOL optic even if the anterior chamber flattens and placing a suture in the phaco incision to ensure its stability.
For cataract patients, the postoperative pressure can be controlled with careful planning and monitoring. Remember that the most common cause of increased IOP in the immediate postop period is retained viscoelastic. Using the angle sweep method to remove the retained OVD from the angle of the eye will help prevent these pressure spikes and ensure better outcomes for our patients.
Full videos and further explanation can be found at www.CataractCoach.com.
- For more information:
- Uday Devgan, MD, is in private practice at Devgan Eye Surgery, Chief of Ophthalmology at Olive View UCLA Medical Center and Clinical Professor of Ophthalmology at the Jules Stein Eye Institute, UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: devgan@gmail.com; website: www.CataractCoach.com.
Disclosure: Devgan reports he owns and operates CataractCoach.com, which is free to all users.