Mechanical dry eye: Early diagnosis is key
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Mechanical dry eye is one of the most common age-related eye diseases.
In a recent study of approximately 1,500 participants older than 60 years (Mimura et al.), more than 98% demonstrated signs of mechanical dry eye (MDE). These data support the fact that age is a leading risk factor for this condition that is characterized by redundant, wrinkled folds of conjunctiva visible at the lid margin. The folds obstruct the punctum and obliterate the normal tear reservoir and meniscus, and patients often present to optometrists complaining of foreign body sensation. At that point, it’s up to us to make a timely and accurate diagnosis, refer them for treatment and then be prepared to expertly manage the follow-up care.
If MDE doesn’t sound familiar, that’s because it is commonly known as conjunctivochalasis (CCh). There has been an ongoing specialty-wide shift to using the term MDE instead of CCh. The rationale is that MDE better describes the clinical condition, whereas CCh is simply an anatomical finding. Hence, MDE is the condition that develops from CCh.
Making the diagnosis
MDE is widely considered difficult to diagnose because its symptoms mimic dry eye, but diagnosis can be easy if you always consider it a possibility when examining older patients who complain of dry eye or foreign body sensation.
With age, patients lose elasticity of the eyelids, resulting in a shortened and wrinkled conjunctiva, which interferes with the tear meniscus and diminishes the fornix or tear reservoir. This is caused by the underlying Tenon’s capsule being degenerated or dissolved by matrix metalloproteinases, or MMPs. The excess folds of loose, wrinkled conjunctiva block the tear reservoir and prevent tears from spreading. This, in turn, causes dry eye and, unfortunately, is far too often treated as such. When the patient blinks, this wrinkled conjunctiva can rub against the eye, causing further irritation and redness to an already inflamed and dry eye. At the slit lamp, look for lid laxity. Pull on the lids to see if there are elasticity issues. The lids typically aren’t taut, and they may have an ectropion appearance.
A critical step in diagnosing MDE is distinguishing it from aqueous tear deficiency after ruling out other types of dry eye. Keep in mind that these patients often present with clinical symptoms of epiphora and sometimes conjunctival hyperemia, and, in my experience, when epiphora is present it’s usually due to a mechanical problem, such as MDE.
Treatment options
When MDE is diagnosed in a patient who is asymptomatic, no treatment is necessary; however, it is appropriate to provide the patient with education about the condition and explain that they’ll need to be seen annually to monitor for potential progression. In cases of mild MDE, artificial tears and topical steroids typically suffice, but patient education and surveillance are appropriate here as well.
When MDE is more advanced, and topical drops and steroids have failed to relieve the foreign body sensation, thermal cautery using a radio frequency device to tack down the loose conjunctiva and Tenon’s capsule is an option. However, the gold standard is a procedure known as reservoir restoration (RR).
Reservoir restoration
RR is a 15-minute, outpatient procedure that restores the tear reservoir and tear meniscus to their natural state and inhibits any further MMP activity. It is performed by an ophthalmic surgeon and relies on the use of cryopreserved amniotic tissue.
The RR procedure entails surgical removal of Tenon's capsule followed by strategic placement of two layers of AmnioGraft (Bio-Tissue), a biologic ocular graft that serves as a tissue replacement. AmnioGraft facilitates therapeutic actions, such as anti-inflammatory and regenerative healing properties that are unique to cryopreserved amniotic membrane.
The combined goals of RR are to rid the patient of the excess tissue; restore a smooth surface so there is no impediment causing irritation and dry eye syndrome; and provide comfort, decrease inflammation and promote healing.
Follow-up care
Usually, the surgeon will surgically treat the patient, and then release the patient back to the care of the referring optometrist. At that point, the patient will be on a 1- or 2-month steroid taper. When the patient returns to my care, I check to see if they are healing properly, if there is any sign of infection — which is rare — and monitor the AmnioGraft to ensure that it stays in place. The patient may have a bit of discomfort and a little redness.
It’s also important to monitor for secondary issues. For instance, if steroids are used for more than a month, an increase in IOP is possible, and steroids can cause secondary infection, although that’s extremely rare.
With the aging population, it is imperative that optometrists recognize and diagnose MDE, refer patients for treatment and provide expert follow-up care. Optometrists who develop an expertise in this area can refer MDE patients to surgeons early in the disease process, thereby improving their quality of life and potentially saving them significant out-of-pocket expenses for misdirected palliative treatments.
References:
- Cooke M, et al. J Wound Care. 2014;doi:10.12968/jowc.2014.23.10.465.
- John T, et al. J Ophthalmol. 2017;doi:10.1155/2017/6404918.
- Mimura T, et al. Am J Ophthalmol. 2009;doi:10.1016/j.ajo.2008.07.010.
- Sakimoto T, et al. Cornea. 2012;doi:10.1097/ICO.0b013e318269ccd0.
- Tseng SC. Invest Ophthalmol Vis Sci. 2016;doi:10.1167/iovs.15-17637.
For more information:
Josh Johnston, OD, FAAO, practices at Georgia Eye Partners, where he focuses on ocular surface disease, including dry eye and other corneal diseases. He can be reached at: josh.johnston@gaeyepartners.com.
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