Cryopreserved amniotic membranes can help optimize outcomes in herpes zoster ophthalmicus
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Of the cases referred to me for management of dry eye, many turn out to be manifestations of nerve damage subsequent to an untreated viral infection, such as herpes zoster ophthalmicus.
Untreated herpes zoster ophthalmicus (HZO) can progress to conditions such as neurotrophic keratitis (NK), in which nerve damage affects the cornea, resulting in chronic intermittent blurred vision, reduction in proper tear production or even loss of vision, frequently accompanied by persistent and severe nerve pain. It is the optometrist’s job to identify HZO and intervene to prevent future neurotrophic damage.
![“I have been using cryopreserved amniotic membranes consistently since 2016, when I first saw what [they] can do for corneal tissue.” Tracy Doll, OD, FAAO](/~/media/slack-news/optometry/misc/infographics/2024/pcon0224doll_graphic_01_web.jpg?w=800)
Diagnosing HZO
HZO infection has some distinct signs and symptoms. HZO follows the pattern of nerves, typically the trigeminal nerve, and is usually unilateral. Skin around the affected eye may appear blistered, and Hutchinson’s sign — a skin lesion on the root, dorsum and apex of one side of the nose — may be present.
The cornea may display what looks like a coalesced punctate keratitis or a pseudodendrite, distinguished from the dendrite seen in herpes simplex by tapered ends on the dendritic points. The patient may have severe pain in the cornea, but in some cases, the cornea may be numb, depending on the extent of damage already done to the corneal nerves. I use a cotton wisp to test for reduced corneal sensitivity on all of my patients presenting for a dry eye evaluation.
While HZO is generally associated with older and immunocompromised patients, it may also occur in younger patients with high levels of stress (Patil A, et al.). A thorough case history is important, checking for herpes simplex, herpes zoster, childhood chicken pox and exposure to the virus. An affirmative response suggests that this patient may have dry eye symptoms from past nerve damage due to a viral infection.
One potential sequela of HZO is NK, a chronic response to damaged corneal nerves that leads to a lack of support for corneal integrity and potentially to vision loss. Signs range from punctate epithelial erosions early on to severe geographic ulcers in stage four. Catching and treating HZO early is key in keeping it from progressing to corneal thinning and ulcers characteristic of NK.
Treating HZO
In my clinic, we follow a protocol that involves using oral antivirals and cryopreserved amniotic membranes (CAMs). For the patient with iritis, I may also prescribe a topical dilating agent, which can help relieve photophobia symptoms. We may use steroids if indicated, as in cases of stromal involvement, but I generally prefer to use CAM in epithelial cases because it does not have the side effects associated with steroids, such as increased intraocular pressure. Moreover, steroids do not help in corneal nerve regeneration, whereas CAM can prevent blood vessel growth or angiogenesis in the cornea.
The goal of treatment goes beyond just re-epithelialization; the nerves are as important as the different layers of epithelia and stroma. It is critical to get patients on oral antivirals as quickly as possible because the infection systemically moves up the nerve branches. As soon as I see the distinct lesion, I also immediately use CAM because I find it quite effective at healing the front surface of the eye.
CAM is stretched across a PMMA plastic ring that goes onto the surface of the eye. Some patients, such as those with glaucoma blebs, are not candidates for a CAM. Also, CAM is cryopreserved, so patients should not have any cross-sensitivities to ciprofloxacin or amphotericin B, which are used in the solution. Whenever possible however, CAM is the preferred treatment because of the anti-inflammatory and anti-angiogenic properties of the membrane, and it stops the fibrogenic growth of scar tissue. This is why I use CAM on any diagnosis that affects the corneal epithelium, particularly a herpetic lesion.
It takes seconds to place CAM on the eye: I rinse the membrane, pull the eyelid up, slide the membrane underneath, the patient closes their eye and I tape it. The final step in this procedure includes taping the eye shut (tape tarsorrhaphy), which stabilizes the CAM and helps relieve some discomfort its presence may cause. The tape also protects the CAM and eye, which some patients need, especially when sleeping. I tell patients that they can continue to do any activity they are comfortable doing with one eye.
I leave the CAM in the affected eye from 2 days to a week, depending on the severity of the symptoms and how long the condition needs to heal. Where the cornea is severely damaged, I may need to use a second CAM or go up to double thickness. I ask my patients to give me a few days to help them heal completely, and I remind them that it will cost more time later if they don’t get their condition under control as soon as possible.
Healing with amniotic membrane
I have been using CAMs consistently since 2016, when I first saw what they can do for corneal tissue. In patients with HZO, we have seen excellent rates of healing. If we can get them in the early stages, we can achieve re-epithelialization quickly, reduce edema and prevent scarring. If I injured my eye or contracted HZO, this is the treatment I’d want from my optometrist. And I would tell other practitioners to start earlier than they think they should; it’s never too early to protect the corneal nerves along with the corneal epithelium.
We now understand how much the nerves matter, especially in HZO. We aim to keep the corneal tissue intact, but to prevent further damage and help prevent NK, we cannot ignore the nerves.
References:
- Ophthalmic pearls: Herpes zoster ophthalmicus. https://www.aao.org/eyenet/article/herpes-zoster-ophthalmicus-pearls. Published January 2020. Accessed March 12, 2024.
- Patil A, et al. Viruses. 2022;doi:10.3390/v14020192.
For more information:
Tracy Doll, OD, FAAO, teaches ocular disease and procedures at Pacific University College of Optometry in Oregon.
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