User:Wendyxieyang/Eye examination

Medical History

Collecting medical history is the first and an essential step in eye examination. Many eye conditions are associated with systemic health, and many diseases can have manifestations in the eye. Certain systematic medications can carry ocular side effects and warrant routine eye exams. Personal and family history of eye diseases can help providers identify individuals at higher risk, allowing for early interventions.

Common Chief Complaints

Common chief complaints for an eye exam include vision loss (transient or persistent), blurry vision, double vision, seeing flashes of light, and seeing floaters. [citations]

Systematic Medical Conditions

Diabetic Mellitus

Diabetic mellitus (insert link to diabetes), or diabetes, can lead to changes in the eye. Individuals with diabetes can develop early cataract and diabetic retinopathy in the long term.

Hypertension

Longstanding hypertension (insert link) can contribute to microvascular damage of the blood vessels in the retina, leading to hypertensive retinopathy.

Malignant hypertension (insert link) can lead to papilledema (insert link), which is the swelling of the optic nerve.

Autoimmune Disorders

Autoimmune disorders can affect the eyes in different ways. Most commonly, Grave's disease can lead to Grave's ophthalmolopathy or Thyroid Eye Disease (TED). Sjogren's disease (insert link) manifest as dry eye.

Medication Use

Hydroxychloroquine

Hydroxychloroquine, also known as Plaquenil, is an antimalaria medication commonly used to treat lupus and rheumatoid arthritis. Individuals who are on long-term hydroxychloroquine for more than 5 years are recommended to have a comprehensive eye exam annually. Patients usually receive a baseline exam before starting the medication to document their baseline eye condition as well.

Steroids

Steroids can have ocular side effects. It can increase the intraocular pressure, which can lead to glaucoma (insert link).

Personal History of Eye Conditions

Collecting one's personal history of eye conditions provides valuable information for the eye examination. History of trauma to the eye, such as open globe injury (insert link), and prior surgeries, such as refractive surgeries (link), cataract surgeries (link), and MIGS procedures (link) are usually gathered during an eye examination.

Family History of Eye Conditions

A family history of glaucoma (insert link), age-related macular degeneration (insert link), and other inherited eye diseases (insert link) are often collected, as these diseases have a genetic component.

Eye examination

Visual Acuity

Main article: 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 a 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, and that represents the distance in meters.

This is often measured with a Snellen chart or LogMAR chart.

Measuring Visual Acuity (need a lot of citations)

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 (insert link) (letters or non-letter symbols). Distance visual acuity and near visual acuity are often measured separated. Usually, one eye is measured at a time, first without corrections (glasses or pinhole), then with corrections.

Best corrected visual acuity (insert link) refers to the best visual acuity one can achieve with corrective lenses. When corrective lenses are not available, a pinhole is often used to simulate the effect of glasses. Any improvement from corrective lenses or/and pinholes are often documented to indicate the individual's refractive potential.

The visual acuity is assigned in the form of a fraction. 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. When an individual correctly identifies additional 2 letters in the next 20/30 lines, then they will be assigned 20/40+2. Alternatively, if an individual correctly identifies all optotypes on the 20/40 lines except 2, they will be assigned 20/40-2.

When an individual cannot read the chart, visual acuity is assessed using alternative methods that do not involve the chart. CF is used when an individual can see and count fingers at a certain distance. For example, CF@2ft' refers to "count fingers at 2 feet". HM (hand motion) is used when an individual can only see the direction of hand movement close to the face. LP (light perception) is used when an individual can only detect light but not shapes, motions or colors. NLP (no light perception) is assigned when an individual cannot detect any light.

Refraction/Optics

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

Using a phoropter to determine a prescription for eyeglasses

Objective refraction

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

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.

***add common refractive errors***

Presbyopia

***consider adding a separate section on these following topics***

The care team

The equipment and instruments used during an eye exam

- probably need a lot of photos