May 2020

GLAUCOMA

Recap of the ASCRS symposium at the 2020 AGS Annual Meeting


by Ellen Stodola Editorial Co-Director

During the 2020 American Glaucoma Society (AGS) Annual Meeting, a joint symposium with ASCRS focused on the “Influence of Glaucoma Surgery on Cornea.”

Endothelial loss

Malik Kahook, MD, discussed “Managing Endothelial Loss After MIGS Procedure.”
Endothelial cell loss (ECL) with trabeculectomy occurs around 9.5–14.5% of the time, he said, while it occurs in 8–24.6% of tube shunts.
ECL is a bit higher but statistically similar between trabecular bypass devices combined with cataract surgery vs. standalone cataract surgery, with up to 3 years of follow-up, he said, noting that the XEN Gel Stent (Allergan) hasn’t been correlated with ECL to date.
Dr. Kahook discussed the recall of CyPass (Alcon) and intervention guidelines from the ASCRS Task Force.
For eyes with 0 or 1 ring of the CyPass device visible in the anterior chamber by gonioscopy, without clear evidence of corneal decompensation, the consensus was that no action other than clinical monitoring is recommended.
For eyes with 2 or 3 rings of the CyPass device visible in the anterior chamber, there is a greater risk of corneal ECL. However, not all eyes in this category will experience clinically meaningful ECL, he said. Without clinically significant evidence of corneal decompensation, no action other than monitoring is indicated.
If corneal decompensation develops and more than 1 ring of the device is visible, the surgeon may consider CyPass repositioning, removal, or proximal end trimming. He added that repositioning the device for deeper implantation would be most safe if performed within 7–10 days of implantation. Device removal, on the other hand, is generally not favored due to fibrosis that can make removal difficult. Trimming of the proximal end is likely the preferred procedure if the patient and physician desire intervention.
Dr. Kahook recommended the following with CyPass today: repeat ECL testing, repeat it again, watch for changes in corneal thickness, identify if the patient is symptomatic, avoid trimming unless the patient has consistent ECL and shows changes in corneal thickness, educate the patient about cell loss with any intraocular surgery, and get a second opinion.
Douglas Rhee, MD, spoke about managing endothelial loss after traditional glaucoma surgery.
Dr. Rhee noted that when looking at data after trabeculectomy and tube shunts, you should be aware of short follow-up in the literature.
He covered some of the risk factors. With trabeculectomy, these include iridocorneal touch, pseudoexfoliation, and uveitic glaucoma, use of mitomycin-C, and higher degree of loss in the cornea by the bleb. With tube shunts, these include pseudoexfoliation and narrow tube-cornea angle on OCT.
In terms of managing risk factors with trabeculectomy, the number one thing is to avoid hypotony to avoid losing endothelial cells, Dr. Rhee said. Intervene quickly when hypotony occurs, and be aware of greater risk of ECD loss in pseudoexfoliation and uveitic glaucoma. For tube shunts, Dr. Rhee stressed the importance of keeping the tube away from the cornea and planar to the iris.
He suggested a slit lamp examination to assess for focal or diffuse corneal stromal edema and/or presence of guttata. To further monitor corneal health, Dr. Rhee suggested corneal thickness and specular microscopy.

Astigmatism

Alan Robin, MD, discussed how glaucoma procedures can create astigmatism.
He said that 72% of patients have some astigmatic shift. It starts with steepening of the vertical meridian. Most will return to normal by 3 months, but some persist for greater than 12 months. Factors in this shift may include size and location of incisions, antimetabolites, cautery, flap, ostomy, and sutures/removal.
Dr. Robin discussed how mitomycin may cause a shift toward vertical flattening and noted the potential correlation between astigmatism and an overhanging bleb. He also said that cautery has been associated with astigmatism in multiple studies, and the use of topical epinephrine on the eye at the beginning of surgery can minimize the need for cautery.
Intraoperatively, Dr. Robin suggested several steps to reduce astigmatism, including reducing cautery, using a smaller sclerostomy to reduce “sinking of the corneal edge of the ostomy internally,” not using overtight or unequal tightness scleral flap sutures, and perhaps using an aberrometer.

Corneal hysteresis

Davinder Grover, MD, covered corneal hysteresis (CH), which he described as the only in vivo measurement of corneal/ocular biomechanics.
CH is an important factor to be considered in the assessment of risk for glaucoma progression. It represents how well an eye can absorb and dissipate energy, Dr. Grover said, adding that CH is an independent risk factor for glaucoma development and progression. It is reflective of overall ocular tissue properties and provides insight into biomechanical principles of the eye.
Dr. Grover said that he will not make clinical decisions in a patient without knowing CH, as it is a “glaucoma vital sign.” He added that he’s more likely to operate on a patient with uncontrolled glaucoma and a low CH than an uncontrolled glaucoma patient with high CH. However, he noted there are no prospective studies that have evaluated CH and glaucoma surgery.
Dr. Grover called central corneal thickness a weak surrogate for CH and a “poor man’s corneal hysteresis.” The take-home point is that a low CH is associated with an increased risk of glaucoma development and progression (usually a CH less than 10 mm Hg), while a higher CH is associated with a lower risk of glaucoma development and progression (usually a CH above 10 mm Hg).

Management of OSD

Laura Voicu, MD, discussed management of ocular surface disease (OSD) before and after glaucoma surgery.
There is a significant amount of OSD among glaucoma patients, and these can be some of the most challenging cases with the addition of devices, topical medications, preservatives, elevated blebs, and anti-metabolite exposure to the eye, she said.
Dr. Voicu discussed lid margin disease, noting that to treat, she first uses hypochlorous acid spray and lid scrubs. In addition, BlephEx is good for in-office treatment of lid margin disease, and doxycycline/minocycline are useful, she said. Dr. Voicu said reducing glaucoma drops helps, and thermopulsation and intense pulsed light therapy can work in certain patients.
Addressing dry eye before glaucoma surgery may be easier than treating what could be worse conditions after surgery. Withdrawal of BAK-containing glaucoma drops in the case of medication toxicity is possible with multiple substitutes available. Significantly elevated blebs or dellen can often be managed with aggressive lubrication (but surgical revision may be required), she said.
Dr. Voicu suggested reducing repeated exposure to antimetabolites in patients with OSD, if possible. To manage limbal stem cell deficiency in glaucoma patients after surgery, Dr. Voicu mentioned amniotic membrane techniques. Postoperatively, she recommended preservative-free steroids and antibiotics.
In some cases of patients with OSD and the need for ongoing glaucoma management, early surgical intervention, including MIGS procedures, can often be beneficial to reduce the burden of topical medications, she said.

About the doctors

Davinder Grover, MD
Glaucoma Associates of Texas
Dallas, Texas

Malik Kahook, MD
UCHealth Sue Anschutz-Rodgers Eye Center
University of Colorado
Aurora, Colorado

Douglas Rhee, MD
University Hospitals/Case Western Reserve University
Cleveland, Ohio

Alan Robin, MD
Associate professor of
ophthalmology and
international health
Johns Hopkins University
Baltimore, Maryland

Laura Voicu, MD
Ophthalmic Consultants of Boston
Boston, Massachusetts

Relevant disclosures

Grover
: Aerie, Allergan, Bausch + Lomb, New World Medical, Reichert Technologies, Glaukos, MicroOptix, New World Medical
Kahook: SpyGlass Ophthalmics, Equinox, Ivantis, Fluent Ophthalmics, ShapeTech, Aurea Medical, Alcon, Johnson & Johnson Vision, New World Medical
Rhee: Aerie, Ivantis, Allergan, Alcon, Ocular Therapeutix, Glaukos
Robin: None
Voicu: New World Medical, Katena

Contact

Grover
: dgrover@glaucomaassociates.com
Kahook: malik.kahook@cuanschutz.edu
Rhee: dougrhee@aol.com
Robin: arobin@glaucomaexpert.com
Voicu: lavoicu@eyeboston.com

Recap of the ASCRS symposium at the 2020 AGS Annual Meeting Recap of the ASCRS symposium at the 2020 AGS Annual Meeting
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