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.

A-scan biometry is an ultrasound test that measures key distances inside the eye. It is most commonly used to plan cataract surgery by helping calculate intraocular lens (IOL) power. It can also be used when the eye’s optical media are cloudy and optical measurements are difficult. The result is a set of precise eye length measurements that clinicians interpret in context.

B-scan ultrasound is an imaging test that uses sound waves to create a cross-sectional picture of the eye and orbit. It is commonly used when the doctor cannot see the back of the eye clearly with light-based exams. It helps evaluate structures like the vitreous (eye gel), retina, and tissues around the eyeball. It is used in eye clinics, emergency settings, and surgical planning when needed.

indocyanine green angiography (ICGA) is an eye imaging test that shows blood flow in deeper layers of the eye. It uses a medical dye and a special camera to capture images of circulation behind the retina. It is most commonly used in retina clinics to evaluate conditions affecting the choroid and retinal vessels. It often complements other tests such as optical coherence tomography (OCT) and fluorescein angiography.

fluorescein angiography (FA) is an eye imaging test that uses a fluorescent dye to photograph blood flow inside the eye. It helps clinicians see how the retina and related tissues are being supplied by blood vessels. It is commonly used in ophthalmology clinics and retina practices to evaluate retinal disease. It can also support optometry and ophthalmology decision-making when retinal vascular problems are suspected.

widefield imaging is an eye imaging approach that captures a broad view of the retina in a single session. It is used to document the back of the eye, including areas farther from the center of vision. Clinics use it to screen, diagnose, and monitor many retinal and vascular eye conditions. It is commonly performed in optometry and ophthalmology offices as part of a retinal evaluation.

fundus photography is a way to take pictures of the back of the eye (the “fundus”). It creates a visual record of the retina, optic nerve head, and retinal blood vessels. It is commonly used in eye clinics, optometry offices, and screening programs. The images help clinicians document eye findings and monitor change over time.

OCT angiography (OCTA) is a non-invasive eye imaging test that maps blood flow in the retina and choroid. It uses an OCT scanner to create “angiography-like” images without injecting dye. Clinicians commonly use it in retina clinics to evaluate macular and optic nerve conditions. It is also used in optometry and ophthalmology settings to monitor vascular changes over time.