Dry eye diagnostics

A methodical approach brings speed without haste in dry eye assessment

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Prof Marc Labetoulle
Dry eye disease (DED) assessment has many pitfalls, but most usual situations can be overcome with a 10-minute examination, said Prof Marc Labetoulle, South Paris University, France, during a keynote address at Cornea Day during the 24th ESCRS Winter Meeting in Marrakech, Morocco. The Tear Film & Ocular Surface Society’s DEWS II guidelines have provided precise yet complex flow charts for the diagnosis procedures and treatment of dry eye disease. However, time constraints mean that, unfortunately, it is not always possible to use them comprehensively in a clinical setting, he noted. In a busy clinic there might be a tendency to rush through the consultation. But there really is no need to do so since a fairly definitive diagnosis of the underlying cause of the patient’s condition and arriving at an appropriate prescription is possible with a five-to-10-minute examination in 90% of dry eye patients, he said. Listen to the patient The first step in the consultation is to listen to the patient's description of their dry eye symptoms. That involves having the patient complete an Ocular Surface Disease Index (OSDI) questionnaire (or equivalent) while still in the waiting room and then hearing the patient’s spontaneous complaints as well as information about risk factors including age, ethnicity, contact lens wear and previous refractive surgery. The patient’s description of the symptoms can provide important diagnostic information. For example, if a patient says their discomfort is the same every day, but if the maximum discomfort is in the morning, then Meibomian gland dysfunction (MGD) is likely a contributor to the condition. However, if the symptoms are most intense during the evening, an aqueous deficiency likely contributes more to the condition. In patients who report having symptoms only at certain times, a complaint of pain that awakens them in the morning is strongly indicative of finger dot dystrophy. If the condition tends to occur only during certain times of year or during certain activities, allergy is a likely aetiological (or associated) suspect, Prof Labetoulle said. Slit-lamp exam pearls Slit-lamp examination can provide further clues to the main mechanism of DED. For example, eyes with mild aqueous deficiency will tend to be very bloodshot with a reduced sheen of the cornea and debris in the tears. In the more severe cases of aqueous deficiency there will be conjunctival folds with confluent staining and/or filaments. In eyes with MGD, the redness and staining will be greatest in the inferior part of the ocular surface and there may be neovascularisation at the limbus. Examination of the eyelid will show inflammation at the edge and plugging and drop-out of Meibomian glands. One should also be careful not to miss signs of other ocular surface diseases, such as superior limbal keratitis, a common cause of recalcitrant dry eye disease that is characterised by conjunctival folds and increased staining in the superior limbus, he advised. He noted that when testing tear break-up time (TBUT) it is important not to instil too much fluorescein, which will overestimate TBUT, or too little fluorescein, which will underestimate it. Prof Labetoulle’s own protocol for reproducible TBUT is to instil a low concentration of fluorescein and wait 20-to-30 seconds, allowing spontaneous blinking, until the green staining is translucent (not too much fluorescein, and not too little). He assesses the TBUT test three times in a row and estimates the mean value. It is also essential to get an idea about the level of tear secretion at least once in the check-up of a new patient, he noted. Schirmer test and phenol red thread tests are reliable, and assistants can be trained to perform them effectively prior to the consultation. Tear meniscus measurement, using optical coherence tomography or corneal topography, can be a practical alternative although there are no precisely validated normal values for the parameter. Include the patient in the treatment strategy Once these tests and examinations are complete, a prescription may be formulated that specifically addresses both the patient’s symptoms and the underlying disease in the majority of cases, Prof Labetoulle said. “The biggest mistakes people make are providing prescriptions without explanation, with successive attempts of a new eye drop after the previous one has failed,” Prof Labetoulle said. Treatment options include liquid solutions such as saline solution and glycol derivatives for hydrating the ocular surface, and vinyl- and cellulose-based gel solutions with mucomimetic properties. There are also drops with both hydrating and mucomimetic properties such as the hyaluronates, he noted. Drops are also available that address osmolarity, or the oxydative stress, to reduce inflammation and some that act as lipid substitutes, which are useful in MGD. Lid hygiene measures are also useful in MGD. For cases where autoimmune disease is a factor, cyclosporine is available. In recalcitrant cases the options include physical treatments to improve lid hygiene, punctal plugs, scleral lenses and autologous serum, he added.
Tags: cornea diagnostics