WHEN ANTI-VEGFs AREN’T AN OPTION, CONSIDER INTRAVITREAL STEROIDS
ANTI-VEGFS HAVE become the gold standard in treating various retinal conditions. Most commonly, these retinal conditions are AMD, diabetic macular edema (DME) and retinal vein occlusion (RVO). But what happens when anti-VEGFs are contraindicated, the patient fails to respond or other therapies, such as laser surgery, are not effective? The answer may be the use of intravitreal steroids.
Here, we discuss intravitreal steroids, the available agents and the O.D.’s role when it comes to this treatment category.
To briefly review, steroids are potent anti-inflammatory agents that contain antiangiogenic and antipermeability properties. Specifically, they stabilize the blood-retinal barrier, reduce exudation and down-regulate inflammatory mediators. Further, steroids inhibit the production of VEGF and stabilize the endothelial and basement membranes, thus, reducing vascular permeability and leakage.
The commonly used intravitreal steroids:
- Triamcinolone acetonide. Intravitreal triamcinolone acetonide is a naturally slow-release, relatively powerful steroid injection. This drug comes in two forms: preservative and preservative-free. The former is Kenalog (Bristol-Myers Squibb) and the latter are Triesence (40 mg/mL, Alcon) and Trivaris (80mg/mL, Allergan). The preservative-free forms lower the risk of complications, such as endophthalmitis and toxicity. The drug is present in the vitreous up to three months after delivery, necessitating possible re-treatment at follow-up.
All these formulations are used off-label for DME or RVO. The 40mg/mL and 80mg/mL formulations of triamcinolone acetonide have been approved for intravitreal injections for inflammatory diseases, such as uveitis, and are prepackaged and preservative-free, thus preventing a potential sterile inflammatory reaction to the vehicle. The formulation of triamcinolone acetonide containing preservatives, Kenalog, is not FDA approved for intraocular use, but it is, nevertheless, commonly used off label.
- Dexamethasone. Dexamethasone has a shorter half-life compared with triamcinolone, but it is more potent.
This intravitreal steroid is available in the biodegradable delivery implant Ozurdex (Allergan), which is designed to provide sustained distribution of 0.7mg of dexamethasone in the vitreous cavity for three to four months. Ozurdex is approved by the FDA for the treatment of DME and macular edema associated with RVO.
- Fluocinolone. This is a synthetic corticosteroid with potency similar to the glucocorticoid dexamethasone. It is available in the non-biodegradable Iluvien (Alimera Sciences) sustained delivery implant or the intravitreal implant Retisert (Bausch + Lomb).
Iluvien 0.19mg is inserted intravitreally. It is FDA approved for the long-term treatment of DME.
Retisert is a 0.59mg pellet that must be implanted surgically. It is FDA approved for non-infectious posterior uveitis.
Both release small doses of fluocinolone acetonide for at least three years.
Various factors, including duration and side effects, are important in determining which intravitreal steroid injection treatment to consider.
Ozurdez is mostly used in the treatment of the DME and edema related to RVO.
Iluvien may be considered in cases of chronic disease punctuated by recurrences, but side effects, such as cataracts, elevated IOP and glaucoma, may occur.
After repeated Ozurdex injections that result in improving either the VA or decreasing central macular thickness on OCT, one may want to consider longer acting, sustained-release implants, such as fluocinolone.
THE O.D.’S ROLE
Although the ophthalmologist determines the treatment for any of the retinal conditions mentioned, we, as optometrists, still play a crucial role regarding these patients’ care.
Specifically, we must provide education about the patient’s retinal condition and the treatment options that could help maintain — or even restore — his or her vision. Of course, before determining what those treatment options may be, we must first determine treatment candidacy.
Regarding intravitreal steroids, it’s important to know that contraindications include ocular surface disease, such as severe blepharitis, active herpetic or fungal disease. Pre-existing steroid-responders, primary open-angle glaucoma, or ocular hypertension may also be contraindications for injections.
If the patient is a candidate for this treatment, we should next explain to him or her what, specifically, occurs and the associated risk of complications.
The patient should be instructed that foreign body sensation is normal following an injection and may not start for several hours after the anesthetic begins to wear off.
Further, the patient should be educated that subconjunctival hemorrhage can occur and may exacerbate foreign body sensation.
Finally, the patient should be made aware of experiencing “floaters,” which is the medicine being visualized as it is suspended within the vitreous cavity, particularly with triamcinolone acetonide.
Follow-up care involves assessment of more serious complications, such as endophthalmitis, which includes eye pain, blurry vision and a severely injected or red eye with evidence of anterior and posterior segment inflammation.
Patients should be closely monitored for increases in IOP, glaucoma, cataract formation and retinal detachment. The good news regarding the latter: Cutting-edge diagnostic technology, such as SD-OCT, OCTA, wide-field imaging and fundus autofluorescence, can aid us in detecting possible recurrence and, therefore, refer the patient back to the ophthalmologist for further intervention. OM