Before you can treat dry eye, you have to diagnose dry eye.
Dry eye is an extremely prevalent ocular condition, and one of the most common reasons patients seek ophthalmology care. But, it’s not the only reason. And dry eye symptoms can be maddeningly similar to complaints caused by a variety of other conditions, including recurrent corneal erosions, floppy eyelid syndrome, blepharitis/Meibomian gland dysfunction, filamentary keratitis, and several others. That makes it crucial to obtain a definitive dry eye diagnosis before initiating treatment. Fortunately, ophthalmologists now have a number of affordable, and easy-to-use diagnostic tools to choose from, any one of which can provide quick, precise and, in many cases, point-of-care diagnosis.
One of the oldest diagnostic tools, the Schirmer’s test, which measures tear production, is still used, though its positive predictive value has been surpassed by newer tests, such as tear osmolarity. In recent years, new technology has emerged that can provide more precise, more detailed information that confirms the dry eye diagnosis and even helps guide treatment.
That technology includes:
• Tear osmolarity. Osmolarity is a well-established indicator of dry eye, indicating a concentrated tear film. Osmolarity can be measured with a very fast diagnostic test – typically it takes about 10 seconds. If osmolarity is normal but InflammaDry (see below) is positive, the patient likely does not have dry eye, but rather inflamed eyes caused by another condition.
• Keratograph 5M. This device from Oculus performs a number of functions, including tear-film assessment. It provides tear meniscus height measurement, tear film lipid layer thickness, automated redness scan, automated tear film breakup time, and detection of tear film particles. The particles are detected, and their movement tracked, providing an assessment of viscosity. Meibography is an additional function of the Keratograph 5M. Meibography is a means to provide photographic documentation of the condition of the Meibomian glands; Meibomian gland dysfunction (MGD) is a common cause of evaporative dry eye. Research has documented that 86-92 percent of patients who have dry eye also have MGD.
• MMP 9 (InflammaDry). Matrix metalloproteinases are proteolytic enzymes produced by stressed epithelial cells on the ocular surface. In patients with dry eye, matrix metalloproteinases-9 (MMP 9) levels are elevated. The MMP-9 detector is a more sensitive diagnostic marker than clinical signs. The detector is a rapid, point-of-care test performed in four steps that detects elevated MMP 9 levels in tear fluid. The test is simple enough that it can be performed by a technician or nurse, and usually provides results within 10 minutes.
• HD Analyzer. Manufactured by Visiometrics, the HD Analyzer allows you to see what your patient sees, and displays images of vision quality fluctuations caused by rapid tear film breakup between blinks. The device measures the influence of tear film on a patient’s quality of vision – in real time. In patients with dry eye, images start crisp immediately after blinking, but those images continue to degrade as the eye stays open. The series of images allow you not only to see dry-eye caused degradation, but to quantify it.
The data provided by these and other diagnostic tools puts a definitive diagnosis of dry eye in your hands quickly, and allows you to initiative appropriate and effective treatment immediately. Investment in diagnostic tools is a key step for any physician committed to creating a dry-eye center of excellence.
Marguerite McDonald, MD, FACS, with OCLI on Long Island, NY, is clinical professor of Ophthalmology at NYU Langone Medical Center, NY, and clinical professor of Ophthalmology at Tulane University Health Sciences Center, New Orleans, Louisiana.