Eyeworld

Supported by unrestricted educational grants from Alcon Laboratories Inc., Allergan Inc., Shire Pharmaceuticals, TearLab, and TearScience by Jessica Ciralsky, MD Finding the root cause: Dry eye diagnostics The right diagnostics help pinpoint causes of dry eye and guide effective management A lthough traditional testing modalities are still important for dry eye disease identification, new- er point-of-care diagnostics can also be used to help cli- nicians differentiate between various conditions and guide treatment, particularly when signs and symptoms do not match. Array of tests Dry eye disease often remains undetected and untreated. However, Ding et al. reported that it affects an estimated 40 million Americans. 1 To more effectively iden- tify patients with dry eye, spe- cific screening questions can be asked during initial history taking, or formal question- naires such as the Ocular Sur- face Disease Index (OSDI) or Standard Patient Evaluation of Eye Dryness (SPEED) can be administered. Questionnaires and directed patient histories can help us pre-identify pa- tients with symptoms indica- tive of dry eye who will need point-of-care testing. Point-of-care diagnostics help us zero in on the correct diagnosis, develop targeted treatment strategies, and monitor treatment responses. When patients have positive results on either a validated questionnaire or on targeted history taking, we start testing for dry eye with a detailed examination and point-of-care testing for os- molarity and MMP-9, which, when abnormal, can also help us track patients' response to treatment. 2,3 Both increased osmolarity of the tear film and inflammation of the ocular surface are part of the definition of dry eye disease, as defined by the Dry Eye WorkShop (DEWS) report. 4 Positive results for MMP- 9 occur when the MMP-9 concentration is greater than 40 ng/ml and indicate the presence of inflammation. Elevated levels of MMP-9 have been seen in the tears of patients with dry eyes. High osmolarity is also observed in patients with dry eye disease. We consider val- ues greater than 308 mOsm/L or inter-eye variability greater than 8 points as indicative of dry eye. Inter-eye variability usually does not occur when the tear film is stable. Tear osmolarity can be an important tool before cataract surgery, as demonstrated by Epitropoulos et al. 5 Average K readings and corneal astigma- tism were significantly more variable in hyperosmolar patients compared with those with normal osmolarity, which influenced power calculations for intraocular lenses. A thorough slit lamp examination with fluorescein or lissamine green staining of the conjunctiva and cor- nea and examination of the lids with expression of the meibum continues to play a major role in the diagnosis of dry eye (Figure 1). Meibomian glands and the lipid layer can be evaluat- ed with meibography, ocular surface interferometry, and tear break-up time. Tear break- up time is a quick test that can indicate tear instability. If patients have blepharitis, ab- normal meibum, or an abnor- mal tear break-up time, I will Figure 1. In patients with severe dry eye, such as this one, diffuse staining is often seen with fluorescein dye. With more mild to moderate cases, however, the staining can be minimal or absent. Other diagnostic tests can help detect earlier cases of dry eye. continued on page 4 Jessica Ciralsky, MD Figure 2: Using high-resolution dynamic meibomian imaging meibography, clinicians can evaluate the meibomian glands in greater detail. Structural changes, which are seen in meibomian gland dysfunction, such as gland atrophy, gland dropout, and duct dilation, can be detected with this technology. 3

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