 Hello. My name is Alex Compton. I'm a fourth year medical student at Texas Tech University Health Sciences Center and today I'm going to be discussing doing an anterior chamber depth estimation using a pen light. Our learning objectives for this session will be first to identify key anatomical structures in the anterior eye, second to understand various uses of the pen light, and lastly to demonstrate how a pen light can be used to estimate the depth of the anterior chamber. So first, the key anatomy of the anterior eye. As we start in the exterior, we will first see the lids and lashes. Next, we will see the white sclera and the transparent cornea. Next, we'll also see the conjunctiva, which is overlying the sclera. We will see the pupil, the black spot in the middle of the eye and the colored iris, and the lens, which helps focus light onto the back of the eye. In this area, between the cornea and the iris, that area is called the anterior chamber, and the area between the iris and the lens is called the posterior chamber. The pen light can be used to determine many different things and is a useful tool to help examine the eye. It can first be used to see gross lesions in the lids, the sclera and the cornea. It can be used to detect pupillary abnormalities, including things such as anisecoria and the relative afferent pupillary defect, or RAPD. And it can also be used to find red reflex. Many of these topics are discussed elsewhere in the Moran Corps, and you can direct your attention to those videos and tutorials if you would like to learn more about these. Being able to estimate the depth of the anterior chamber with a pen light is a quick and straightforward way to assess a patient in a case of suspected acute angle closure glaucoma. We will now demonstrate how to do this. First, you want to position the patient so that they are comfortable and so that you have easy access to the temporal side of the eye being examined while being able to see directly into the eye. Next, you want to turn your pen light on and examine the eye from the temporal side. You do not want to be too far behind the eye or too far forward as this will give an inaccurate result. You want to try to be in the same plane as the iris. Lastly, know if there is any shadow on the iris in the nasal portion. In a normal patient such as this, you will see the light being able to shine all the way across the iris. However, in a patient with a suspected acute angle closure glaucoma, you will see a shadow begin to creep across the nasal side of the iris as the anterior chamber begins to be pushed forward. Thank you. Here is a picture further illustrating what your exam might look like. In a normal patient, you will be able to see the whole iris illuminated as you shine the light from the temporal side as the anterior chamber is at a normal depth. However, if the anterior chamber is being pushed forward and the chamber depth is relatively shallow, a shadow will come across the nasal portion of the eye as depicted in the second diagram seen here. Thank you.