Testing for Dry Eyes

 

There are multiple tests your optometrist or ophthalmologist, will perform to both diagnose the type and severity of your dry eye disease. The also use these tests to monitor how your eyelid and tear health changes over time and the the affect of treatment. Multiple tests are also beneficial because, like the symptoms and causes of dry eye, the results of various dry eye tests differ depending on your individual eyes. The symptoms you have of dry eyes don't always match the signs your optometrist or ophthalmologist will see

 

Talking to You.

The history of your symptoms, your general health, your medications and past eye history all play a role in your dry eye disease. Your diet and lifestyle may also given insight into what may be causing and aggravating your symptoms. A good chat about these things aids in the diagnosis and also developing the best management plan.

 

Staining.

Assessing for Corneal and Conjunctival Staining with gentle dyes serves as an indicator of the health of the ocular surface. Commonly orange Fluorescein dye is used which highlights areas of dryness where the surface epithelium is damaged. Lissamine Green is also an excellent dye as it can shown staining in Dry Eye patients earlier in the disease process.

 

Osmolarity Testing.

Hyperosmolarity (saltiness) of the tear film is recognised as a factor in dry eye syndrome. Increased osmolarity has also been shown to cause inflammation and damage to epithelial cells. Your osmolarity level can be measured by collecting a small sample of your tears.

 

Meibomian Gland Expression.

As meibomian gland dysfunction (MGD) the leading cause of dry eye. On examination as well as assessing the structure of the glands with Meibography, gland expression is important to assess the quality of the meibum in the glands. Your glands might be not expressing at all, expressing poor quality oil, or be slow to express thick, stagnant meibum.

 

Tear Break Up Times.

Tear Break Up Time (TBUT) is a measure of how quickly your tears evaporate. This may be measured with a gentle orange dye called Fluorescein Sodium or with advanced equipment to measure Non-Invasive TBUT. The latter is considered more accurate but both methods hold value in practice. Normal results of TBUT are 10 seconds or more.

 

Slit Lamp Examination.

You should be familiar with the slit lamp. This is the microscope your eye care practitioner uses to assess the overall health and appearance of your eyes. With dry, sore or irritated eyes they will be looking at your eyelid position; your lash position and levels of debris; for any redness on the lids or eye; the clarity of your conjunctiva and cornea; and the quality of your tears.

 

Meibography.

Meibography is the imaging of your meibomian glands to help determine if they are blocked or if there is structural damage to the glands. This can be done with specialised equipment and is important in determining the best treatment options to give you results.

 

Inflammatory (MMP-9) Markers.

As inflammation plays a role in Dry Eye it can be beneficial to look for biomarkers of inflammation. The InflammaDry Test does that - it looks for elevated levels of MMP-9 in the tears. MMP-9 has been shown to be elevated in the tears of patients with Dry Eye & Ocular Surface disease. In can be useful in deciding if anti-inflammatories are a good course of treatment.

 

Ocular Surface Interferometry.

An ocular surface interferometer collects images and provides a means to precisely measure tear film thickness and quantify lipid levels in the tear film. This advanced piece of equipment allows for both initial diagnosis of MGD and tracking progression and treatment response.

 

Tear Volume.

This is a measure of the volume of tears on your eyes. If there’s low volume it can be indicative of aqueous deficient dry eye. Most commonly the Tear Meniscus or Tear Prism Height is measured. The quality of the tears will also be assessed - they should be even, not gritty, foamy or have mucous in them. Meniscus heights less than 0.2mm are considered low.  

 

Questionnaires.

Questionnaires can be very useful in assessing your symptoms, their severity and the effect of treatment. These questionnaires are a way of putting a number to your symptoms to help track changes over time. They also can help identify triggers. Examples include the Ocular Surface Disease Index (OSDI), the OSDI-6, the DEQ-5 and the SPEED Questionnaire.

 

Blink Dynamics.

A good eye care provider will look at how often and how well you blink. If you have a slow blink rate or perform incomplete blinks this will impact your ocular surface health. Blink rates also reduce during certain tasks, like reading and computer work.

 

Schirmer Test & Phenol Red Thread Test

These tests are another measure of tear volume and production. The Schirmer test uses a thin paper strip and the Phenol Red Thread uses a thread to look at the volume of tears over time. It sits over your eyelid for a set period of time and then the length of wetting is measured. Normal Schirmer is 13-15mm, borderline is 6-10mm and less than 6mm indicates dry eye.