An eye examination is a series of tests performed to assess vision and ability to focus on and discern objects. It also includes other tests and examinations pertaining to the eyes. Eye examinations are primarily performed by an

optometrist Optometry is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities. Optometrists are health care professionals who typically provide comprehensive primary eye care. In the Un ...

ophthalmologist Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a med ...

, or an orthoptist. Health care professionals often recommend that all people should have periodic and thorough eye examinations as part of routine primary care, especially since many eye diseases are

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered a ...

. Eye examinations may detect potentially treatable blinding eye diseases, ocular manifestations of systemic disease, or signs of

tumour A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s or other anomalies of the

brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

. A full eye examination consists of an external examination, followed by specific tests for

visual acuity Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, i.e. (1) the sharpness of the retinal ...

pupil The pupil is a black hole located in the center of the Iris (anatomy), iris of the Human eye, eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing ...

function, extraocular muscle motility,

visual field The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a poin ...

s, intraocular pressure and ophthalmoscopy through a dilated pupil. A minimal eye examination consists of tests for visual acuity, pupil function, and extraocular muscle motility, as well as direct ophthalmoscopy through an undilated pupil.

Basic examination

Visual acuity

Visual acuity is the eyes ability to detect fine details and is the quantitative measure of the eye's ability to see an in-focus image at a certain distance. The standard definition of normal visual acuity (20/20 or 6/6 vision) is the ability to resolve a spatial pattern separated by a visual angle of one minute of arc. The terms 20/20 and 6/6 are derived from standardized sized objects that can be seen by a "person of normal vision" at the specified distance. For example, if one can see at a distance of 20 ft an object that normally can be seen at 20 ft, then one has 20/20 vision. If one can see at 20 ft what a normal person can see at 40 ft, then one has 20/40 vision. Put another way, suppose you have trouble seeing objects at a distance and you can only see out to 20 ft what a person with normal vision can see out to 200 feet, then you have 20/200 vision. The 6/6 terminology is used in countries using the

metric system The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Intern ...

, and that represents the distance in metres. This is often measured with a Snellen chart or LogMAR chart

Refraction

In physics, "

refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomen ...

" is the mechanism that bends the path of light as it passes from one medium to another, as when it passes from the air through the parts of the eye. In an eye exam, the term refraction is the determination of the ideal correction of refractive error.

Refractive error Refractive error, also known as refraction error, is a problem with focusing light accurately on the retina due to the shape of the eye and or cornea. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism ...

is an optical abnormality in which the shape of the eye fails to bring light into sharp focus on the retina, resulting in blurred or distorted vision. Examples of refractive error are

myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may includ ...

hyperopia Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, i ...

, presbyopia and

astigmatism Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at n ...

. The errors are specified in diopters, in a similar format to an eyeglass prescription. A refraction procedure consists of two parts: objective and subjective.

Objective refraction

An objective refraction is a refraction obtained without receiving any feedback from the patient, using a retinoscope or

auto-refractor An autorefractor or automated refractor is a computer-controlled machine used during an eye examination to provide an objective measurement of a person's refractive error and prescription for glasses or contact lenses. This is achieved by measur ...

. To perform a retinoscopy, the doctor projects a streak of light into a pupil. A series of lenses are flashed in front of the eye. By looking through the retinoscope, the doctor can study the light reflex of the pupil. Based on the movement and orientation of this retinal reflection, the refractive state of the eye is measured. An auto-refractor is a computerized instrument that shines light into an eye. The light travels through the front of the eye, to the back and then forward through the front again. The information bounced back to the instrument gives an objective measurement of refractive error without asking the patients any questions.

Subjective refraction

A subjective refraction requires responses from the patient. Typically, the patient will sit behind a phoropter or wear a trial frame and look at an eye chart. The eye care professional will change lenses and other settings while asking the patient for feedback on which set of lenses give the best vision.

Cycloplegic refraction

Sometimes, eye care professionals prefer to obtain a cycloplegic refraction, especially when trying to obtain an accurate refraction in young children who may skew refraction measurements by adjusting their eyes with accommodation. Cycloplegic eye drops are applied to the eye to temporarily paralyze the ciliary muscle of the eye.

Pupil function

An examination of pupilary function includes inspecting the pupils for equal size (1 mm or less of difference may be normal), regular shape, reactivity to light, and direct and consensual accommodation. These steps can be easily remembered with the

mnemonic A mnemonic ( ) device, or memory device, is any learning technique that aids information retention or retrieval (remembering) in the human memory for better understanding. Mnemonics make use of elaborative encoding, retrieval cues, and image ...

''PERRLA (D+C)'': Pupils Equal and Round; Reactive to Light and Accommodation (Direct and Consensual). A swinging-flashlight test may also be desirable if neurologic damage is suspected. The swinging-flashlight test is the most useful clinical test available to a general physician for the assessment of

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived fro ...

anomalies. This test detects the afferent pupil defect, also referred to as the Marcus Gunn pupil. It is conducted in a semidarkened room. In a normal reaction to the swinging-flashlight test, both pupils constrict when one is exposed to

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

. As the light is being moved from one eye to another, both eyes begin to dilate, but constrict again when light has reached the other eye. If there is an efferent defect in the left eye, the left pupil will remain dilated regardless of where the light is shining, while the right pupil will respond normally. If there is an afferent defect in the left eye, both pupils will dilate when the light is shining on the left eye, but both will constrict when it is shining on the right eye. This is because the left eye will not respond to external stimulus (afferent pathway), but can still receive neural signals from the brain (efferent pathway) to constrict. If there is a unilateral small pupil with normal reactivity to light, it is unlikely that a

neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or o ...

is present. However, if accompanied by ptosis of the upper

eyelid An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. The human eye ...

, this may indicate

Horner's syndrome Horner's syndrome, also known as oculosympathetic paresis, is a combination of symptoms that arises when a group of nerves known as the sympathetic trunk is damaged. The signs and symptoms occur on the same side (ipsilateral) as it is a lesion ...

. If there is a small, irregular pupil that constricts poorly to light, but normally to accommodation, this is an

Argyll Robertson pupil Argyll Robertson pupils (AR pupils) are bilateral small pupils that reduce in size on a near object (i.e., they accommodate), but do ''not'' constrict when exposed to bright light (i.e., they do not react). They are a highly specific sign of neu ...

Ocular motility

Ocular motility should always be tested, especially when patients complain of double vision or physicians suspect neurologic disease. First, the doctor should visually assess the eyes for deviations that could result from strabismus, extraocular muscle dysfunction, or

palsy Palsy is a medical term which refers to various types of paralysisDan Agin, ''More Than Genes: What Science Can Tell Us About Toxic Chemicals, Development, and the Risk to Our Children;; (2009), p. 172. or paresis, often accompanied by weakness a ...

of the cranial nerves innervating the extraocular muscles.

Saccade A saccade ( , French for ''jerk'') is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishi ...

s are assessed by having the patient move his or her eye quickly to a target at the far right, left, top and bottom. This tests for saccadic dysfunction whereupon poor ability of the eyes to "jump" from one place to another may impinge on reading ability and other skills, whereby the eyes are required to fixate and follow a desired object. The patient is asked to follow a target with both eyes as it is moved in each of the nine cardinal directions of gaze. The examiner notes the speed, smoothness, range and symmetry of movements and observes for unsteadiness of fixation. These nine fields of gaze test the extraocular muscles: inferior,

superior Superior may refer to: *Superior (hierarchy), something which is higher in a hierarchical structure of any kind Places *Superior (proposed U.S. state), an unsuccessful proposal for the Upper Peninsula of Michigan to form a separate state *Lake ...

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

and medial rectus

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

s, as well as the

and inferior oblique muscles.

Visual field (confrontation) testing

Testing the visual fields consists of confrontation field testing in which each eye is tested separately to assess the extent of the peripheral field. To perform the test, the individual occludes one eye while fixated on the examiner's eye with the non-occluded eye. The patient is then asked to count the number of fingers that are briefly flashed in each of the four quadrants. This method is preferred to the ''wiggly finger test'' that was historically used because it represents a rapid and efficient way of answering the same question: is the peripheral visual field affected? Common problems of the visual field include

scotoma A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision. Every normal mam ...

(area of reduced vision), hemianopia (half of visual field lost),

homonymous hemianopsia Hemianopsia, or hemianopia, is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia (or homonymous hemianopia) is hemianopic visual field loss on the s ...

and

bitemporal hemianopia Bitemporal hemianopsia, is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the opt ...

External examination

External examination of eyes consists of inspection of the

s, surrounding tissues and palpebral fissure. Palpation of the orbital rim may also be desirable, depending on the presenting signs and symptoms. The

conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithel ...

and

sclera The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and so ...

can be inspected by having the individual look up, and shining a light while retracting the upper or lower eyelid. The position of the eyelids are checked for abnormalities such as ptosis which is an asymmetry between eyelid positions.

Slit-lamp

Close inspection of the anterior eye structures and ocular adnexa are often done with a slit lamp which is a table mounted microscope with a special adjustable illumination source attached. A small beam of light that can be varied in width, height, incident angle, orientation and colour, is passed over the eye. Often, this light beam is narrowed into a vertical "slit", during slit-lamp examination. The examiner views the illuminated ocular structures, through an optical system that magnifies the image of the eye and the patient is seated while being examined, and the head stabilized by an adjustable chin rest. This allows inspection of all the ocular media, from cornea to vitreous, plus magnified view of eyelids, and other external ocular related structures.

Fluorescein Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is widely used ...

staining before slit lamp examination may reveal corneal abrasions or herpes simplex infection. The binocular slit-lamp examination provides stereoscopic magnified view of the eye structures in striking detail, enabling exact anatomical diagnoses to be made for a variety of eye conditions. Also ophthalmoscopy and gonioscopy examinations can also be performed through the slit lamp when combined with special lenses. These lenses include the Goldmann 3-mirror lens, gonioscopy single-mirror/Zeiss 4-mirror lens for (ocular) anterior chamber angle structures and +90D lens, +78D lens, +66D lens & Hruby (-56D) lens, the examination of retinal structures is accomplished.

Intraocular pressure

Intraocular pressure (IOP) can be measured by

tonometry Tonometry is the procedure eye care professionals perform to determine the intraocular pressure (IOP), the fluid pressure inside the eye. It is an important test in the evaluation of patients at risk from glaucoma. Most tonometers are calibrated ...

devices. The eye can be thought of as an enclosed compartment through which there is a constant circulation of fluid that maintains its shape and internal pressure. Tonometry is a method of measuring this pressure using various instruments. The normal range is 10-21 mmHg.

Retinal examination

Examination of retina (fundus examination) is an important part of the general eye examination. Dilating the pupil using special eye drops greatly enhances the view and permits an extensive examination of peripheral retina. A limited view can be obtained through an undilated pupil, in which case best results are obtained with the room darkened and the patient looking towards the far corner. The appearance of the

optic disc The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form ...

and retinal vasculature are also recorded during fundus examination. A red reflex can be seen when looking at a patient's pupil through a direct ophthalmoscope. This part of the examination is done from a distance of about 50 cm and is usually symmetrical between the two eyes. An opacity may indicate a cataract. Man at Phoropter

Retinal vessel analysis Retinal vessel analysis is a non-invasive method to examine the small arteries and veins in the retina which allows to draw conclusions about the morphology and the function of small vessels elsewhere in the human body. Retinal vessel analysis is ...

is a non-invasive method to examine the small arteries and veins in the retina which allows to draw conclusions about the morphology and the function of small vessels elsewhere in the human body and is used in particular by

cardiologist Cardiology () is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular ...

s as well as

Eye exams for children

It is often recommended that children should have their first eye exam at six months old, or earlier if a parent suspects something is wrong with the eyes. Across the world, screening programs are important for identifying children who have a need for spectacles but either do not wear any or have the wrong prescription. Children need the following basic visual skills for learning: * Near vision * Distance vision: Tumbling E chart, Landolt C chart * Eye teaming ( binocularity) * Eye movement * Accommodation (focusing skills) * Peripheral vision *

Eye–hand coordination Eye–hand coordination (also known as hand–eye coordination) is the coordinated control of eye movement with hand movement and the processing of visual input to guide reaching and grasping along with the use of proprioception of the hands to ...

Conditions diagnosed during eye examinations

Myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may includ ...

Hyperopia Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, i ...

* Presbyopia *

Amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...

Diplopia Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...

Astigmatism Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at n ...

* Strabismus

Specialized eye examinations

Color vision Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different wavelengths (i.e., different spectral power distributions) independently of light intensity. Color perception is a part of ...

* Stereopsis * Near point of convergence *

Keratometry A keratometer, also known as an ophthalmometer, is a diagnostic instrument for measuring the curvature of the anterior surface of the cornea, particularly for assessing the extent and axis of astigmatism. It was invented by the German physiologi ...

* Cycloplegic refraction * Accommodative system ** Amplitude of accommodation ** Negative relative accommodation ** Positive relative accommodation * Vergence system * Optokinetic system * Amsler grid * Gonioscopy *

Corneal topography Corneal topography, also known as photokeratoscopy or videokeratography, is a non-invasive medical imaging technique for mapping the anterior curvature of the cornea, the outer structure of the eye. Since the cornea is normally responsible for som ...

* Corneal pachymetry * Scheimpflug ocular imaging * Retinal tomography * Ocular computed tomography * Scanning laser polarimetry * Electrooculography * Electroretinography * Ultrasound biomicroscopy *

Maddox rod The Maddox rod test can be used to subjectively detect and measure a latent, manifest, horizontal or vertical strabismus for near and distance. The test is based on the principle of diplopic projection. Dissociation of the deviation is brought abo ...

Brock string A Brock string (named after Frederick W. Brock) is an instrument used in vision therapy. It consists of a white string of approximately 10 feet in length with three small wooden beads of different colors. The Brock string is commonly employed du ...

* Convergence Testing * Worth 4 dot test *

Pulfrich effect The Pulfrich effect is a psychophysical percept wherein lateral motion of an object in the field of view is interpreted by the visual cortex as having a depth component, due to a relative difference in signal timings between the two eyes. Overvie ...

References

External links

Medscape article on Neuro-ophthalmic examination
{{Eye procedures Diagnostic ophthalmology Medical mnemonics Optometry Physical examination