Exploring the controversial side of conjunctivitis

Contentions abound from prevalence to treatment

Conjunctivitis
Source: Manolette Roque, M.D.

Conjunctivitis is one of the most common ailments that ophthalmic practitioners are called to treat. Still, this remains an area filled with contention from prevalence estimates to treatment regimens, according to Marguerite B. McDonald, M.D., professor of ophthalmology, New York University School of Medicine, New York, and adjunct clinical professor of ophthalmology, Tulane University Health Sciences Center, New Orleans.
In a study published in the August 2009 issue of Current Medical Research and Opinion, a panel of experts recently convened to discuss what the literature had to say about such controversies.
Dr. McDonald, who took part in the roundtable discussion, finds that there is controversy even regarding the prevalence of the condition.
“Approximately 20 to 70% of infectious conjunctivitis is thought to be of viral ideology,” Dr. McDonald said. “That’s an outrageously wide range.” Likewise, between 65% and 90% of cases are thought to be caused by adenovirus specifically.
Such varying numbers may potentially be influenced by where the study is conducted, Dr. McDonald theorized. “Adenoviral conjunctivitis tends to occur in areas of overcrowding with poor hygiene where people are crammed together; it is extremely contagious,” Dr. McDonald said. “So depending upon where you conduct your study, you’ll get a different percentage.”

Diagnostic dilemmas

Conjunctivitis has varying origins. “Acute conjunctivitis is typically caused by an infection with viruses, bacteria, or chlamydia,” Dr. McDonald said. “Also, patients can have acute conjunctivitis resulting from chemical injury or medication.”
With potential cases of conjunctivitis, practitioners need to take a good history and then look for signs of the condition as well. “It’s very important to do a good physical exam at the slit lamp to look for common signs such as vesicles, papules, ulcerations, crusting, discharge, and chemosis,” Dr. McDonald said. “A serous or serosanguinous discharge is more likely to occur with viral infections, and a purulent discharge tends to occur with bacterial conjunctivitis.”
There are other key differences as well. “Viral disease tends to produce more chemosis,” Dr. McDonald said. “Also, the palpebral conjunctiva has to be examined very carefully for the presence of a follicular reaction—if you find follicles it’s much more likely that you have a case of viral conjunctivitis.” Meanwhile papillary reaction is more common with bacteria and allergies. However, moraxeloa conjunctivitis, which is of bacterial origin, can also cause follicles. “Often when you look at the slit lamp you see follicles, papillae, or in some cases, a mixed reaction,” Dr. McDonald said. “So when there are both follicles and papillae, it’s not easy to determine what the ideological cause is or even to determine which pattern predominates.”
In addition, conjunctival signs may be different for children than for adults. “Children often have a benign folliculosis,” Dr. McDonald said. “This can confound the clinical picture because they have this all the time.”
By looking for these and other signs, practitioners make what can be a difficult call. Also of contention is the error rate that practitioners have when relying on such signs alone. “Clinicians are overconfident about their ability to make a definitive clinical diagnosis on signs and symptoms alone,” Dr. McDonald said. “In studies, clinical accuracy ranges from 40 to 75%.”
Dr. McDonald cites one particular study involving corneal specialists that shows how difficult proper diagnosis can be for the condition. “A national group of clinicians at 16 academic centers with expertise in external diseases were chosen to participate in a study to evaluate cidofovir’s efficacy against adenoviral activity,” Dr. McDonald said. “At the study’s conclusion, these world-famous experts had a clinical accuracy of 48% in diagnosis of adenoviral conjunctivitis.”
For practitioners who are not ophthalmologists, the call can be even more difficult. “Individuals outside of ophthalmology are even less equipped to make the diagnosis,” Dr. McDonald said. “Without the aid of a biomicroscope or laboratory-based technology, differentiating viral from bacterial conjunctivitis is virtually impossible.”

Screening options

Currently the gold standard in making a diagnosis is confirmatory immunofluorescence (CC-IFA). However, this is not used too frequently because it can be time consuming. “By the time you get the results, the viral conjunctivitis is almost gone,” Dr. McDonald said.
Also, polymerase chain reaction (PCR) can be done, but this is also contentious. “PCR has better sensitivity compared to CC-IFA, but typically it requires sending out a specimen to a special lab that handles this sort of testing, and there is a considerable time delay in receiving the results,” Dr. McDonald said. “There are also considerable costs associated with that.”
Laboratory antigen tests tend to be too difficult for practitioners’ offices and are unreliable. “These are too complex for use in the average doctor’s office,” Dr. McDonald said. She pointed out that such assays have only been found to have a 38% sensitivity in cases diagnosed after the first week—within the first week this increases to 65%.
One relatively new test may help to change this. The RPS Adeno Detector (Rapid Pathogen Screening, Inc., South Williamsport, Pa.), is the first point of care test for physicians’ office use. “This doesn’t have to be performed in a traditional laboratory setting and only takes 10 minutes,” Dr. McDonald said.
There are several clinical benefits. “If you have something like this in the office it reduces the number of misdiagnosis, leads to better patient management, better treatment, and it gives answers to patients before they leave the office so that you can sit down and go over the plan,” Dr. McDonald said. “Patients know immediately if they can go back to work and if they require antibiotics.”
Right now for viral cases care is supportive, and for bacterial conjunctivitis patients, Dr. McDonald prescribes a fluoroquinolone four times a day for at least a week. Some practitioners also recommend an antibiotic ointment at night. Patients are also advised to take hygienic precautions.
Even such antibiotic treatment is considered controversial by some. “Some recent European studies suggest not treating conjunctivitis because the duration of the disease is typically only reduced by one to two days,” Dr. McDonald said. “However, this recommendation doesn’t really account for the reduction in infectivity that presumably occurs with appropriate treatment.”
Overall, Dr. McDonald thinks that practitioners have turned a corner with conjunctivitis. “A lot of the myths about conjunctivitis that have persisted for years are being debunked by emerging evidence,” she said. “We have shed considerable light on the problem, and I think there will be research and development into new ophthalmic antiviral agents with specific activity against adenovirus.”

Editors’ note: Dr. McDonald has financial interests with Allergan (Irvine, Calif.) and Santen (Napa, Calif.).

Contact information

McDonald: 516-593-7709, margueritemcdonaldmd@aol.com