By Mok Hao Ting, Yong Loo Lin School of Medicine, National University of Singapore
Dry eye is a common condition that occurs when your tears are unable to provide adequate lubrication for your eyes. It often co-exists with another common condition called blepharitis. Ms Por Jia Yee Davina, an optometrist in International Eye Cataract Retina Centre, discussed the symptoms and clinical features of these conditions in her lecture titled “Dry Eye and Blepharitis: Symptoms, Signs and Diagnosis” at the Singapore Primary Eye Care Symposium (SPECS) 2019 held at One Farrer Hotel on 23-24 July 2019.
Dry eye is a multifactorial disease of the ocular surface characterised by a loss of homeostasis of the tear film. Tear film instability, increased tear osmolarity and ocular surface inflammation are frequently associated with this condition. There are multiple components to the tear film – the mucin layer, aqueous layer and lipid layer, each playing a specific role in maintaining the stability of the tear film. Firstly, the inner mucin layer provides the underlying cornea with nourishment and helps the eye remain moist and lubricated. Secondly, the aqueous layer lubricates the eye, washes away debris and prevents infection. Lastly, the outer lipid layer, produced by the Meibomian gland, aids in reducing the evaporation of tears.
Dry eye may present itself in patients in various forms. Typical symptoms include grittiness, foreign body sensation, burning sensation, sharp pain, itch, blurred vision, tearing and eye redness. Clinical assessments should be carried out to evaluate the patient’s tear production and stability. A tear production test can be conducted via the Schirmer’s test or using phenol red thread. Additionally, staining the patient’s tear film with fluorescein and assessing the tear film break-up time could be used to assess the tear film stability.
Blepharitis is an inflammation of the eyelids, commonly caused by blocked Meibomian glands. These glands secrete oil to prevent quick evaporation of tears, and this contributes to a build-up of a layer of biofilm with bacteria. Over time, this biofilm becomes a toxic environment and the growth of bacteria causes inflammation of the lids and Meibomian glands. This results in the secretion of poor quality oil that harden over surface and blocks the glands. Common symptoms include red and swollen eyelids, burning or stinging eyes, intermittent blurring of vision and crusty debris at the base of eyelashes. Clinically, eye care professionals should check for the presence of crusting or scales on eyelids, frothy tears or thick secretion of oil when expressing the Meibomian glands, as these are possible indicators of blepharitis.
Blepharitis and dry eye are both chronic conditions that persist for many months to years. Ms Por advised that eye care professionals should take special notice of the associated signs and symptoms of these conditions and carry out the respective clinical assessments to make a proper diagnosis.