Meibography and Tear Scan Using the Oculus Keratograph 4

Meibomian gland dysfunction (MGD) is a common clinical condition and a major cause of evaporative dry eye with associated discomfort, visual disturbance and contact lens intolerance. In MGD, meibum is often abnormal, progressively changing in color from clear to yellow and in consistency from liquid to thick and toothpaste-like. Evaluation of the meibomian glands (MG) and lipid layer is vital. In a typical clinical setting, lid and lid margin evaluation is often performed via slitlamp biomicroscopy; however, the structure of the meibomian glands is often not clearly visualized when a slit lamp is used in isolation. Trans-illumination of the lids is necessary to clearly view these glands.

To date, infrared meibography has been the only method available for the assessment of meibomian gland structure. It is primarily regarded as a laboratory-specific procedure for meibomian gland drop out assessment in people suffering from MGD. Recently, the Keratograph 4 was released by OCULUS (Wetzlar, Germany). In addition to corneal and contact lens assessment features, the Keratograph 4 offers a tear film (TF) scan module able to objectively assess tear break-up time (TBUT) with a colour coded map highlighting the regions of tear break up. High-resolution images of tear meniscus can also be obtained and used for subjective assessment of tear meniscus height (TMH) with the help of built-in software. Preliminary research at the Centre for Contact Lens Research has demonstrated its ability to capture meibography images of the upper and lower lids.

The objectives of this study are to collect meibography, TBUT and TMH data using the Keratograph 4 in normal participants (no MGD) and participants with MGD and to compare these between the two groups and before and after the use of a meibomian gland evaluator. The primary outcome variables are meibography images, TBUT and TMH.

The study hypothesis is that here will be a difference between normal participants and participants with MGD, with respect to meibography images (MG drop out), TBUT measurements (area and time of break up) and TMH measurements.

Inclusion criteria

• Is at least 17 years of age and has full legal capacity to volunteer
• Has read and signed an information consent letter
• Is willing and able to follow instructions and maintain the appointment schedule
• Has had an ocular examination in the last two years
• Clinical criteria defining non-dry eye (controls) for study inclusion (Group 1):

• Composite symptom score of ≤ 12 on the OSDI questionnaire
• Meibum secretion quality score of 0 (grade 0-3) at the central eight meibomian glands of the lower lid, in both eyes. Secretion quality score (grade 0-3):

Grade 0 = normal, clear oil expressed (i.e., cooking oil appearance) Grade 1= opaque, diffusely turbid, normal viscosity Grade 2 = opaque, increased viscosity Grade 3 = inspissated (i.e., toothpaste-like appearance) or no expressed material Clinical criteria defining MGD dry eye for study inclusion (Group 2):

• Composite symptom score of ≥ 13 on the OSDI questionnaire
• Meibum secretion quality score ≥ 1.0 (grade 0-3) at the central eight meibomian glands of the lower lid, in both eyes. Secretion quality score (grade 0-3):

Grade 0 = normal, clear oil expressed (i.e., cooking oil appearance) Grade 1 = opaque, diffusely turbid, normal viscosity Grade 2 = opaque, increased viscosity Grade 3 = inspissated (i.e., toothpaste-like appearance) or no expressed material

Exclusion criteria

• Is a current contact lens wearer
• Has any ocular disease
• Is using any topical medications that may affect ocular health
• Has known sensitivity to the diagnostic pharmaceuticals to be used in the study