Certain systematic medications can carry ocular side effects and warrant routine eye exams.

[3] Personal and family history of eye diseases can help providers identify individuals at higher risk, allowing for early interventions.

Visual acuity is usually measured with a Snellen or LogMAR chart with a lit background to give the reader the best chance of detecting the optotypes (letters or non-letter symbols).

Visual acuity is recorded as "20/20" (or another fraction like 20/40) when all optotypes (letters or symbols) on a specific line of the eye chart are correctly identified.

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 PERRLA (D+C): Pupils Equal and Round; Reactive to Light and Accommodation (Direct and Consensual).

Ocular motility should always be tested, especially when patients complain of double vision or physicians suspect neurologic disease.

Saccades are assessed by having the patient move his or her eye quickly to a target at the far right, left, top and bottom.

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.

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.

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?

External examination of eyes consists of inspection of the eyelids, surrounding tissues and palpebral fissure.

Palpation of the orbital rim may also be performed depending on the presenting signs and symptoms, especially when a fracture is suspected or there was a history of trauma to the head.

[12] The conjunctiva and sclera can be inspected by having the individual look up, and shining a light while retracting the upper or lower eyelid.

[12] 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 adjusted to vary in width, height, incident angle, orientation and color, is passed over the eye.

Fluorescein staining of the tear film before slit lamp examination may reveal etiologies of the surface of the eye, such as corneal abrasions or keratitis due to herpes simplex viral infection.

These exams help to see the specific structures, such as the retina and optic nerve, which is at the back of the eye, and the drainage system that controls the intraocular pressure, which is in the angle formed between the cornea and the iris.

Refractive error 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.

The information bounced back to the instrument gives an objective measurement of refractive error without asking the patients any questions.

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.

[14] Often, children who are suspected of having amblyopia are too young to be able to verbally recognize letters on the Snellen chart, making the eye examination challenging.

[17] Refractive errors, congenital or early childhood cataract, and strabismus, can all contribute to the development of amblyopia.

[13] Specific details that might be collected include maternal health, gestation age at birth, and neonatal history.

Close attention is paid to the infant's visual behaviors, such as tracking and following moving items or people, head position, and abnormal facial features.

[18][19] Screening of ROP is often initiated promptly while the infants are still in the hospital, and they are often followed up closely in the first few weeks to months of life to monitor the normal development of blood vessels in the premature retina.

[13] An object is presented from far peripheral and slowly moves into the center of the vision, while the child maintains fixation on a central target.

[13] The point at which the peripheral object captures the child’s attention and prompts a shift in gaze or fixation marks the boundary of their visual field.

Children need the following basic visual skills for learning: Media related to Eye examinations at Wikimedia Commons