Assessment of the Occuity PM1 Pachymeter

To determine whether the Occuity PM1 device is non-inferior in measuring central corneal thickness when compared to ultrasound pachymetry, the Lenstar and the Pentacam. The Investigation aims to assess long-term safety of the Occuity PM1 device when used under the conditions and for the purposes intended, to ensure it will not compromise the clinical condition or the safety of patients, or the safety and health of users or, where applicable, other persons. The central corneal thickness measurements taken by the three devices: Occuity PM1, the ultrasound pachymeter and Lenstar. Demonstrating that the Occuity PM1 Pachymeter is not inferior to the LenStar in terms of equivalency to a 95% confidence level using the Bland Altmen equation/approach based on +/-20micron equivalency. The investigators would like to measure the thickness of the cornea, which is the clear window at the front of the eye. A corneal thickness measurement is important for several reasons. The measurement can tell an eye care professional if the cornea is swollen, which may mean the particiapnt have an increase in fluid within the cornea. Also, assessing corneal thickness can help in the diagnosis of glaucoma and the measurement is important if the participant is going to have eye surgery. The instruments that are currently in use are usually very large and quite expensive and therefore not ideal for use as part of routine eye care. Some instruments require contact with the surface of the eye, which may be uncomfortable. Occuity Ltd. is a medical device company based in Reading, which has been investigating this. They have developed a new instrument (called the 'PM1 Pachymeter') for measuring the thickness of the cornea. The instrument shines a harmless low power beam into the eye and then measures the light reflected back from the eye in order to check the thickness of the cornea. The low power beam is not a visible light and so the participant will not be able to see it. s study will assess how closely the eye measurements taken from the new PM1 Pachymeter matches eye measurements taken from two other devices that are currently on the market. The goal is to provide a non-contact, hand-held meter that is fast and easy to use without the need to contact the eye.