Challenges to the Ocular Surface
Challenges to the Ocular Surface
Whether preparing for surgery or just ensuring good visual acuity, patients need a surface that's lubricated and healthy.
By Victor L. Perez, MD
Nature asks a lot of the ocular surface. As the first line of defense against the environment, it must protect the structures of the eye while staying healthy and lubricated through countless challenges. It's amazing that such a delicate structure, so exposed to environmental insults, can do such an effective job.
But the ocular surface isn't always healthy and lubricated. Ocular surface disease (OSD) is common. It causes discomfort and affects patients' activities, and because the ocular surface is crucial to clear vision, most problems also compromise visual acuity.
For patients' overall health and good vision — as well as to prepare patients for surgery — we're continually working to improve our ability to diagnose those sometimes-elusive causes of OSD and determine the most appropriate treatments.
Identifying the Problem
We're learning more about how the ocular surface works. It's important to understand the production and composition of ocular secretions, as well as how these secretions can be interrupted by disease. Of course, we also understand the inflammatory component of OSD far better than we did in the past, and that knowledge has led to more effective treatments.
But even as we learn to appreciate and understand the delicate balance that exists on the ocular surface, we're still faced with the fact that there's no easy path to diagnose its diseases. Sometimes, the cause of redness, irritation, foreign body sensation and compromised visual acuity is patently clear. Other times, it takes both testing and careful questioning to uncover the true cause of the problem.
At Bascom Palmer Eye Institute, I see a bit of everything — ocular surface disease related to autoimmune disorders, ocular burns, dry eye, meibomian gland dysfunction and post-transplant graft-versus-host disease, which attacks membranous tissues. And as a corneal specialist, I need to take care of any ocular surface problem before cataract surgery or corneal transplant.
As a result, we've become very aggressive in our attempts to improve our diagnosis of OSD. We use multiple questionnaires to pinpoint the details of patients' symptoms, the time of day they occur and the type of secretions described by patients. A thorough evaluation includes an examination of the lids, tear film tear breakup and novel non-invasive imaging of the ocular surface with high resolution anterior segment OCT. All of these details help to narrow down and eventually determine the culprits of ocular surface disease, thus allowing us to provide patients with an accurate diagnosis.
Ocular surface disease is most often related to either evaporative or inflammatory dry eye, but there are many different diagnoses. Questionnaires and testing direct our diagnosis.
■ Dry eye syndrome is perhaps the most common ocular surface disease. The problem is easy to diagnose in its end stage, but in its early stages, it can be difficult. Patients may have early symptoms, but signs may not appear in the cornea.
Dry eye affects many people. Risk increases with age, and women are more likely to have this problem, especially during or after menopause. That said, many other factors put a wide variety of patients at risk, including a dry environment, computer use, contact lens wear, and refractive surgery, as well as other health problems such as rosacea and autoimmune diseases.
No matter what the cause, the signs and symptoms are quite similar. Patients complain of dry, gritty, red eyes and inability to wear contact lenses. We can see visual acuity problems and corneal thickening. A Schirmer's test shows tear production is low, fluorescein shows low tear volume, and a tear breakup test shows that tears respond poorly to challenges. The eye isn't lubricated and protected, so it becomes inflamed. Topical anti-inflammatories, artificial tears, and cyclosporine can calm the eyes, and contact lens wearers may benefit from new lenses designed with this problem in mind.
■ Keratitis may be infectious or noninfectious, but it isn't always easy to tell the difference. Patients generally present with red, inflamed corneas. They may complain of eye pain, light sensitivity, blurring, watering or discharge, and foreign body sensation. In cases of bacterial infection, these symptoms can come on suddenly. Patients with noninfectious keratitis typically have an intact epithelium, and their eyes look clear and sterile.
In Miami, we see a great deal of infection, usually in patients wearing contact lenses for an extended time, causing corneal infiltrate. If there is any infection, we must address it quickly, but sometimes the only way to diagnose infection with certainty is to wait for the results of a culture.
The infection may be bacterial or viral, such as herpes type 1 or herpes zoster. I strongly suspect infection when I see a contact lens wearer or patient with a history of trauma with dense infiltration of the stroma in a ring pattern.
Because infection is potentially dangerous, if we suspect infection, we culture the eye but begin aggressive treatment for infection right away. It's better to err on the side of caution and treat as an infection than to risk the serious consequences of overlooking a suspected but unconfirmed infection.
■ Lacrimal gland problems are typically secondary to systemic disease. I see many patients with Sjogren's syndrome and other autoimmune disorders such as rheumatoid arthritis, lupus, or scleroderma, and their dry eye is often partly attributable to lacrimal gland problems. These patients have inflammatory cells, so their lacrimal glands and accessory lacrimal glands in the conjunctiva are infiltrated with lymphocytes and become inflamed. We treat the problem with a topical combination of cyclosporine and a lubricant.
■ Ocular allergies are very common. Patients may have seasonal allergies to pollen or perennial allergies to household matter, such as dust, but the reaction is the same: itchy, watery, red, puffy eyes that often happen alongside other allergy symptoms such as sneezing or a runny nose. A slit lamp exam shows papilla behind the lid. Antihistamine drops help clear the eyes and make them more comfortable.
■ Anterior blepharitis elicits many of the same patient complaints as dry eye, such as dry, red, puffy, watery, itchy eyes. But patients also may tell us that their eyes burn or get blurry, and their eyelashes are crusty when they wake up. The exam may reveal photophobia, frothy tears, a chalazion, and dandruff and other debris in the lid margin.
Patients with anterior blepharitis may have a bacterial infection of the lids or scalp dandruff. Because it may not be clear whether infection is present, it's best to start patients off with a topical antibiotic, as well as lid scrubs and warm compresses, which the patient should continue long term.
■ Meibomian gland dysfunction is a common cause of dry eye, and it shares the typical dry eye symptoms — predominantly redness and dryness. Foreign body sensation and puffiness are common. Patients with rosacea often have problems with the meibomian glands. The lids are not producing and distributing the oils that keep tears from evaporating, and dryness leads to inflammation.
In the exam room, the slit lamp exam shows lid inflammation. Tear volume is low and tears break up quickly. A lissamine green test may show conjunctival or corneal staining. But the clearest evidence that the patient has meibomian gland dysfunction comes from examining and expressing the glands. Many times, we can see that the glands are plugged. Expression usually reveals a thick, semi-opaque secretion.
Topical anti-inflammatory medication and lubricating drops calm the eyes, and patients may need antibiotic. Warm compresses help thin the plugs and secretions as well.
■ Medication reaction can happen when a patient with an acute bacterial or viral infection is put on a really toxic antibiotic. But more often, it occurs in patients using a preserved topical medication for a chronic ocular problem. In the cornea specialty, we see patients from the glaucoma side using chronic therapy, and preservatives have taken a toll on the ocular surface. That can be difficult because, of course, patients need their glaucoma medication, and sometimes I need to contact the glaucoma specialist to discuss surgery.
Patients who are feeling the effects of preserved drops have an inflamed ocular surface that typically looks red and feels irritated. The general approach is to remove the patient from chronic therapy or change medications, and if that's not possible, look into non-topical treatments. If the patient stops using the chronic therapy, then unpreserved anti-inflammatory drops should calm their eyes.
Treatment Targets the Problem
In the past, I think we tried to treat all ocular surface disease the same way. We followed our gut feeling in the diagnosis and stuck to a few standard approaches. But our ability to diagnose ocular surface disease has improved, and so have the treatment options.
A patient with obvious aqueous deficient dry eye still gets tear replacement, observation and punctal plugs. But in cases where dry eye compromises the status of the ocular surface, we've become more aggressive. For example, patients with MGD are taught how to massage their lids and use warm compresses to clear dandruff and thick, oily secretions. We can offer them not only lubrication, but also anti-inflammatory drops and, in some cases, antibiotics to help reduce inflammation and provide eventual relief.
New treatments are more effective and often provide a faster way to calm the ocular surface and return patients to healthy baseline vision before surgery. Before I can perform corneal transplant or cataract surgery, at the very least, I must bring the vision back to par, which means keeping the ocular surface well lubricated and pristine. This is critical for good vision, particularly when we need to fulfill the high expectations that patients have for today's intraocular lenses. Surgery will induce some changes to the ocular surface, so if patients have problems before surgery, then even a perfect procedure may not have perfect results.
A clear diagnosis and effective treatment of ocular surface disease makes patients more comfortable, lets them do the activities they want to do, and improves their vision before and after surgery.
Corneal specialist Victor L. Perez, MD
, is an associate professor of ophthalmology at Bascom Palmer Eye Institute, Miami.
Optometric Management, Issue: November 2010