lid eversion means gently turning an eyelid outward to see the inner lid surface. It is most often done to examine the upper eyelid and the tissue behind it. Clinicians use it during routine eye exams and urgent evaluations for irritation or pain. It helps reveal problems that can hide under the lid, such as a foreign body or inflammation.

meibography is an eye imaging test that shows the structure of the meibomian glands inside the eyelids. It is most often used to evaluate dry eye related to meibomian gland dysfunction (MGD). The images help clinicians see gland loss, shortening, or blockage patterns more clearly than with a routine external view. It is commonly performed in optometry and ophthalmology clinics as part of ocular surface and dry eye evaluations.

tear osmolarity is a measurement of how concentrated the tear film is on the surface of the eye. It reflects the balance between water, salts (electrolytes), and other tear components. It is commonly used in eye clinics as part of dry eye disease evaluation and ocular surface assessment. It helps clinicians interpret symptoms and signs that may not always match.

rose bengal is a diagnostic dye used in eye exams to highlight certain problems on the eye’s surface. It is most often used in ophthalmology and optometry clinics during a slit-lamp exam. The dye can make damaged or unprotected areas of the cornea and conjunctiva easier to see. It is commonly discussed in the context of dry eye disease and other ocular surface disorders.

lissamine green is a diagnostic dye used during eye exams to highlight certain ocular surface changes. It helps clinicians see patterns of staining on the conjunctiva and cornea more clearly. It is most commonly used in dry eye and other ocular surface disease evaluations. It is applied as a drop or via a moistened dye strip in the clinic.

fluorescein is a fluorescent dye used to help clinicians see eye surface changes and certain blood vessels more clearly. It is commonly used in eye exams in optometry and ophthalmology clinics. In small amounts on the eye, it highlights scratches, dry spots, and contact lens fit patterns. When given into a vein for imaging, it can help map blood flow in the retina.

ocular surface staining is a clinical test that uses special dyes to highlight the surface of the eye. It helps clinicians see areas where the cornea or conjunctiva may be dry, irritated, or damaged. It is commonly performed during eye exams in optometry and ophthalmology clinics. It is often used when people have symptoms like burning, foreign-body sensation, or fluctuating vision.

Schirmer test is a simple clinical test that measures tear production. It uses a small paper strip placed near the lower eyelid to see how much it wets over time. It is commonly used in eye clinics to evaluate dry eye disease and related conditions. It may be performed by ophthalmologists, optometrists, and trained clinical staff.

tear breakup time (TBUT) is a clinical measure of how long the tear film stays smooth after a blink. It helps clinicians understand tear film stability on the front surface of the eye. It is commonly used when evaluating dry eye disease, contact lens comfort, and fluctuating vision. It can also be part of pre-operative screening before procedures like cataract or refractive surgery.

A keratograph is an eye-imaging device used to assess the shape and surface of the cornea (the clear front window of the eye). It commonly uses reflected light patterns to map corneal curvature and related measurements. Many keratograph systems also evaluate the tear film and eyelid glands that support comfortable vision. It is widely used in optometry and ophthalmology clinics for diagnostics, contact lens fitting, and surgical planning.

biometry means measuring the eye’s physical dimensions with specialized instruments. In eye care, it most often refers to measurements used to plan cataract surgery and choose an intraocular lens (IOL). It can also support refractive surgery planning and help document eye growth or anatomy over time. Results are numerical and are interpreted by clinicians alongside the rest of the eye exam.

IOL biometry is a set of eye measurements used to plan intraocular lens (IOL) power for cataract and lens-based surgery. In plain terms, it helps clinicians estimate what “lens strength” should replace the eye’s natural lens. It is commonly performed before cataract surgery, refractive lens exchange, or some secondary IOL procedures. The goal is to support more predictable vision after surgery.

axial length is the front-to-back length of the eye, measured along its visual axis. It is commonly defined as the distance from the front surface of the cornea to the retina at the back of the eye. Clinicians use axial length as a core eye measurement in cataract surgery planning and in myopia (nearsightedness) evaluation. It is also used in research and clinical monitoring of eye growth and certain eye disease risks.

keratometry readings are measurements of the cornea’s curvature (its front surface shape). They are commonly written as “K” values, often with a flat and a steep meridian. Clinicians use them to estimate corneal focusing power and corneal astigmatism. They are routinely collected in optometry and ophthalmology clinics, especially before contact lens fitting and cataract surgery planning.

endothelial cell count is a measurement of the number of cells in the corneal endothelium. The corneal endothelium is the thin inner cell layer on the back surface of the cornea. This count is commonly obtained with specialized imaging during eye exams and before certain eye surgeries. It helps clinicians understand how well the cornea can stay clear.

specular microscopy is an eye imaging test that photographs the inner layer of the cornea. It is mainly used to evaluate corneal endothelial cells, which help keep the cornea clear. Clinics commonly use it before and after eye surgery and when corneal disease is suspected. The test produces cell measurements and images that can be compared over time.

corneal tomography is an eye imaging test that creates a 3D map of the cornea. It measures corneal shape and thickness across a wide area, including the front and back surfaces. It is commonly used in refractive surgery screening and in diagnosing corneal disorders. It also helps clinicians monitor change over time using repeat scans.

corneal topography is an imaging test that maps the shape and curvature of the cornea, the clear front “window” of the eye. It creates color-coded maps that help clinicians understand how light is likely to focus as it enters the eye. It is commonly used in optometry and ophthalmology clinics for contact lens fitting and for evaluating corneal conditions. It is also used before and after many refractive and corneal surgeries to support planning and monitoring.

anterior segment OCT is an imaging test that creates cross-sectional “slice” pictures of the front part of the eye. It uses light to map structures like the cornea, iris, and the drainage angle. Clinics use it to support diagnosis, monitor change over time, and plan or assess procedures. It is commonly found in ophthalmology and optometry practices, especially in cornea, glaucoma, and cataract care.

ultrasound biomicroscopy (UBM) is a high-frequency ultrasound test that creates detailed images of the front part of the eye. It helps clinicians see structures that are difficult to view directly, including areas behind the iris (the colored part of the eye). It is commonly used in glaucoma evaluation, anterior segment (front-of-eye) assessment, and surgical planning. It is a diagnostic imaging tool, not a treatment.