Eye Examination is a series of tests performed by an ophthalmologist (doctor), ophthalmologist, or orthoptic assessment and the ability to focus on and distinguish objects, as well as other tests and examinations related to the eye.. Healthcare professionals often recommend that everyone should undergo periodic and thorough eye examinations as part of routine primary care, especially since many asymptomatic eye diseases.
Eye examinations can detect potentially curable eye diseases, ocular manifestations of systemic disease, or signs of tumors or other brain anomalies.
Ideally, an eye exam consists of an external examination, followed by specific tests for visual acuity, pupil function, extraocular muscle motility, visual plane, intraocular pressure and ophthalmoscopy through enlarged pupils.
Minimal eye examinations consist of tests for visual acuity, pupillary function, and extraocular muscle motility, as well as direct ophthalmoscopy through unfiltered pupils.
Video Eye examination
Basic checks
Visual acuity
Visual acuity is the ability of the eye to detect fine detail and is a quantitative measure of the ability of the eye to see the image focus at a certain distance. The standard definition of normal visual acuity (20/20 or 6/6 vision) is the ability to complete spatial patterns separated by the visual angle of one minute arc. The terms 20/20 and 6/6 come from standard-sized objects that can be seen by "people with normal vision" at a specified distance. For example, if one can see at a distance of 20 ft an object that can usually be seen at 20 feet, then one has a 20/20 vision. If one can see at 20 ft what a normal person can see at 40 feet, then someone has 20/40 eyesight. In other words, suppose you have trouble seeing objects from a distance and you can only see up to 20 feet from what someone with normal eyesight can see up to 200 feet, then you have 20/200 vision. Terminology 6/6 is more commonly used in Europe and Australia, and represents distances in meters.
These are often measured with Snellen graphics or on the basis of logMAR Velourum Visual Acuity System.
Refraction
In physics, "refraction" is the mechanism that deflects the path of light through the eye. In the eye exam, the term refraction is the determination of an ideal refractive bias correction. The bias error is an optical abnormality in which the shape of the eye fails to bring light into the sharp focus on the retina, resulting in blurred or distorted vision. Examples of refractive errors are myopia, hyperopia, and astigmatism. The refraction procedure consists of two parts: objective and subjective.
Objection objective
Objective refraction is refraction obtained without receiving feedback from the patient, using a retinoscope or auto-refractor.
To perform retinoscopy, doctors project a beam of light into the pupil. A series of lenses are thrown in sight. By looking through the retinoscope, doctors can study the pupil's light reflex. Based on the movement and orientation of this retinal reflection, the state of the eye bias is measured.
An auto refractor is a computerized instrument that shines light to the eye. Light moves through the front of the eye, backward and then forward through the front again. Information bounces back to the instrument provides an objective measurement of biased error without asking the patient a question.
Subjective rejection
Subjective refraction requires responses from the patient. Usually, the patient will sit behind a phoropter or use a trial frame and look at the eye chart. Professional eye care will change the lens and other settings when asking the patient for feedback that set the lens gives the best vision.
Researchers at MIT Media Laboratory have proposed eyepieces and software for use with smartphones as a cheaper alternative to traditional subjective bias equipment. This system is called NETRA ("a tool close to the eye for bias assessment"). The patent was filed for the system in 2010, and the primary audience for the device is projected into a developing world where access to eye care professionals is limited. The system uses small lens arrays and small hole grids that require an observer to visualize depth in what is otherwise a 2-dimensional surface (the smartphone screen). Instead of determining which of the two images looks more clear, the patient just needs to line up the array of dots and lines until they overlap. The level of patent adjustment used on handheld optical devices to complete these tasks is a measure of visual acuity that can then be translated into prescription glasses. Binocular refractor measures ball, cylinder, axis, and pupil distance. EyeNetra, the company that markets the device, expects to bring them to market in February 2016 for a price of more than US $ 1,000 per device.
Cycloplegic Refraction
Sometimes, eye care professionals prefer to get cycloplegic refraction, especially when trying to get accurate refraction in children who can perform refractive measurements by adjusting their eyes to accommodation. Cycloplegic eye drops are applied to the eye to temporarily temporarily cure the ciliary muscles of the eye.
Student function
Examination of the pupil function includes checking the pupils for the same size (1 mm or less of the difference may be normal), regular form, reactivity to light, and direct and consensual accommodation. These steps can be easily remembered with mnemonic PERRLA (DC) : P upils E qual and R ound ; R go to L ight and A ccommodation ( D irect and C onsensual).
Swing test may also be desirable if neurological damage is suspected. The swing-flashlight test is the most useful clinical test available to GPs for assessment of optic nerve anomalies. This test detects the afferent pupillary defect, also referred to as the student of Marcus Gunn. It was done in a semi-enclosed room. In a normal reaction to the swing test, the two pupils narrow as one is exposed to light. As light is moved from one eye to the other, the eyes begin to expand, but narrow again when the 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 shines, while the right pupil will respond normally. If there is an afferent defect in the left eye, the pupils will enlarge when the light shines in the left eye, but both will narrow as it shines in the right eye. This is because the left eye will not respond to external stimuli (afferent pathways), but can still receive neural signals from the brain (the efferent pathway) to narrow.
If there is a small unilateral pupil with normal reactivity to light, neuropathy may not be present. However, if accompanied by ptosis of the upper eyelid, this may indicate Horner's syndrome.
If there are irregular small pupils that constrict badly to light, but usually for accommodation, this is the student of Argyll Robertson.
Ocular motility
Ocular motility should always be tested, especially when the patient complains of double vision or the doctor suspects neurological disease. First, the physician should assess the eye visually for deviations that may occur due to strabismus, extraocular muscle dysfunction, or cranial nerve palsy that involves extraocular muscles. Saccade was assessed by asking the patient to move his eyes quickly to the target on the right, left, top, and bottom ends. This test for saccadic dysfunction in which poor eye ability to "jump" from one place to another can affect reading ability and other skills, where the eye is required to fix and follow the desired object.
Patients are asked to follow the target with both eyes when moved in each of the nine directions of the wind. The examiner records the speed, smoothness, range and motion symmetry and observes the instability of fixation. These nine areas of gaze test the extraocular muscles: the inferior, superior, lateral and medial rectus muscles, as well as the superior and inferior oblique muscles.
Visual field testing (confrontation)
Visual field testing consists of a field of confrontation testing in which each eye is tested separately to assess the extent of the peripheral plane.
To perform the test, the individual closes one eye while glued to the examiner's eye with unclogged eyes. The patient is then asked to count the number of fingers briefly flash in each of the four quadrants. This method is preferred over the finger shake test which historically is used because it represents a fast and efficient way of answering the same question: is the peripheral visual field affected?
Common problems in the visual field include scotomas (reduced vision areas), hemianopia (half the field of vision lost), homemade hemianopsia and bitemporal hemianopia.
External checks
External eye examination consists of examination of the eyelids, surrounding tissues and palpebral fissures. Palpation of the orbital rim may also be desirable, depending on the signs and symptoms that appear. The conjunctiva and sclera can be examined by having the individual seek, and shine the light while pulling the upper or lower eyelids. The position of the eyelid is examined for abnormalities such as ptosis which is the asymmetry between the eyelid position.
Slit-lamp
Close examination of the anterior eye structure and ocular adnexa is often performed with a slit light which is a microscope mounted on a table with a customized lighting source attached. Small light rays that can vary width, height, coming angle, orientation and color, are passed over the eye. Often, these rays narrow into a vertical "gap", during a gap inspection. The examiner sees the illuminated ocular structure, through an optical system that enlarges the eye image and the patient sits while examined, and the head is stabilized by the adjustable chin.
This allows the examination of all ocular media, from cornea to vitreous, plus enlarged eyelid view, and other external ocular related structures. Fluorescence staining prior to a gap examination may reveal corneal abrasion or herpes simplex infection.
Inspection of the binocular slit-lamp provides a stereoscopically enlarged eye view with striking detail, enabling an appropriate diagnosis of anatomy for various eye conditions.
Examination of ophthalmoscopy and gonioscopy can also be done through a slit lamp when combined with a special lens. These lenses include a 3-mirror Goldmann lens, a single-mirror/Zeiss 4-mirror gonioskopy lens for the anterior chamber (ocular) angle structure and a 90D lens, a 78D lens, a 66D & amp; Hruby Lens (-56D), examination of retinal structures is complete.
Intraocular pressure
Intraocular pressure (IOP) can be measured with Tonometry devices. The eye can be regarded as a closed compartment where there is a constant fluid circulation that maintains its internal shape and pressure. Tonometry is a method of measuring this pressure using various instruments. The normal range is 10-21 mmHg.
Retinal examination
Retinal examination (fundus examination) is an important part of general eye examination. Widening the pupils using special eye drops greatly enhances the view and allows extensive examination of the peripheral retina. Limited views can be obtained through unfiltered pupils, whereby the best results are obtained with darker rooms and the patient is looking to the far corner. The appearance of optical discs and retinal vascularization was also noted during fundus examination.
Red reflexes can be seen when looking at the patient's pupils via 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. Opacity may show cataracts.
Maps Eye examination
Eye check for children
Children should undergo their first eye exam at 6 months of age. If the parents suspect something is wrong, the ophthalmologist can check early.
Early eye examination is important because children need the following basic visual skills to learn:
- Close vision
- Distance of vision: Tumbling Graph E, Landolt C chart
- The eye timing (binocularity)
- Eye movements
- Accommodation (focus skills)
- Peripheral vision
- Eye-hand coordination
Conditions diagnosed during eye examination
- Myopia
- Hyperopia
- Presbyopia
- Amblyopia
- Diplopia
- Strabismus
Custom eye check
- Vivid color
- Stereopsis
- Near the convergence point
- Keratometry
- Cycloplegic refraction
- Accommodative system
- Amplitude of accommodation
- Accommodation is relatively negative
- Accommodation is relatively positive
- Vergen System
- The optokinetic system
- Amsler Grid
- Gonioscopy
- Corneal topography
- corneal pachimetry
- Scheimpflug ocular imagery
- Retina tomography
- Ocular tomographic computation
- Scans the laser polarimetry
- Electrooculography
- Electroretinography
- Ultrasonic biomicroscope
- Maddox bar
- String Brock
- Convergence Testing
- Deserves 4 point test
- Pulfrich effect
See also
References
External links
- Simulator for eye movements and student function tests
- eMedicine articles on the Neuro-ophthalmic examination
Source of the article : Wikipedia
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