The eye can be examined with routine equipment, including a standard ophthalmoscope; thorough examination requires special equipment and evaluation by an ophthalmologist. Examination includes, visual acuity, Visual field test, Pinhole test, direct ophthalmoscope and others.
History includes location, speed of onset, and duration of current symptoms and history of previous ocular symptoms. The presence and nature of pain, discharge, or redness; and changes in visual acuity. Worrisome symptoms besides vision loss and eye pain include flashing lights, showers of floaters (both of which may be symptoms of retinal detachment), diplopia, and loss of peripheral vision.
to check the history part please refer to the following link . Introduction to ophthalmology (power point presentation)
The first step is to record visual acuity. Many patients do not give full effort. Providing adequate time and coaxing patients tend to yield more accurate results. Visual acuity is measured with and without the patient’s own glasses. If patients do not have their glasses, a pinhole refractor is used. If a commercial pinhole refractor is unavailable, one can be made at the bedside by poking holes through a piece of cardboard using an 18-gauge needle and varying the diameter of each hole slightly.
Usually, a Pinhole can correct up to +4 to -4 of refraction. Pinhole is a helpful screening test. It sorts out whether the problem of the eye is refractive or organic. Visual acuity in each eye is tested as the opposite eye is covered with a solid object (not the patient’s fingers, which may separate during testing). Patients look at an eye chart 20 ft (6 m) away. If this test cannot be done, acuity can be measured by using a chart held about 36 cm (14 in) from the eye.
Normal and abnormal vision is quantified by Snellen notation. A Snellen notation of 20/40 (6/12) indicates that the smallest letter that can be read by someone with normal vision at 40 ft (12 m) has to be brought to 20 ft (6 m) before it is recognized by the patient. Vision is recorded as the smallest line in which the patient can read half of the letters, even if the patient feels that the letters are blurry or they have to guess. If the patient cannot read the top line of the Snellen chart at 20 ft (6 m), acuity is tested at 10 ft (3 m).
If nothing can be read from a chart even at the closest distance, the examiner holds up different numbers of fingers to see whether the patient can accurately count them. If not, the examiner tests whether the patient can perceive hand motion.
If not, a light is shined into the eye to see whether light is perceived.
Near vision is checked by asking patients to read a standard near card or newsprint at 14 in (36 cm); patients > 40 yr who require corrective lenses (reading glasses) should wear them during near vision testing.
Refractive error can be estimated roughly with a handheld ophthalmoscope by noting the lens necessary for the examiner to focus on the retina; this procedure requires examiners to use their own corrective lenses and is never a substitute for a comprehensive assessment of refraction.
More commonly, refractive error is measured with a standard phoropter or an automated refractor (a device that measures changes in light projected and reflected by the patient’s eye). These devices also measure astigmatism.
How to take visual acuity for children?
Children might be quite challenging. Some might be shy, others might have developmental delay or they might not up to the adequate age to cooperate with the examiner.
In this case we use the cover uncover test to see if the patient cries when one eye is closed. This is call objection sign.
Another important way of assessment is the use of cyclo-refration in children. the examiner rely on the clinical judgment to make adequate eye glasses for the child. it is very common to find a +2 to +3 refraction in those children.
Eyelid and conjunctival examination
Eyelid margins and periocular cutaneous tissues are examined under a focal light and magnification (eg, provided by loupe, slit lamp, or ophthalmoscope).
After eyelid eversion, the palpebral and bulbar conjunctivae and the fornices can be inspected for foreign bodies, signs of inflammation (eg, follicular hypertrophy, exudate, hyperemia, edema), or other abnormalities.
Indistinct or blurred edges of the corneal light reflex (a reflection of light from the cornea when illuminated) suggest the corneal surface is not intact or is roughened, as occurs with a corneal abrasion or keratitis.
Fluorescein staining reveals abrasions and ulcers. Before staining, a drop of topical anesthetic (eg, proparacaine 0.5%, tetracaine 0.5%) may be added to facilitate examination if the patient is in pain or if it is necessary to touch the cornea or conjunctiva (eg, to remove a foreign body or measure intraocular pressure).
A sterile, individually packaged fluorescein strip is moistened with 1 drop of sterile saline or topical anesthetic and, with the patient’s eye looking upward, is touched momentarily to the inside of the lower eyelid. The patient blinks several times to spread the dye into the tear film, and then the eye is examined under magnification and cobalt blue illumination. Areas where the corneal or conjunctival epithelium is absent (abraded or ulcerated) fluoresce green.
The size and shape of the pupils are noted, and pupillary reaction to light is tested in each eye, one at a time, while the patient looks in the distance. Then the swinging flashlight test is done with a penlight to compare direct and consensual pupillary response. There are 3 steps:
- One pupil is maximally constricted by being exposed to light from the penlight for 1 to 3 sec.
- The penlight is rapidly moved to the other eye for 1 to 3 sec.
- The light is moved back to the first eye.
Normally, a pupil constricts similarly when light is shone on it (direct response) and when light is shone on the other eye (consensual response).
However, if one eye has less light perception than the other, as caused by dysfunction of the afferent limb (from the optic nerve to the optic chiasm) or extensive retinal disease, then the consensual response in the affected eye is stronger than the direct response.
Thus, on step 3 of the swinging light test, when the light is shone back on the affected eye, it paradoxically appears to dilate. This finding indicates a relative afferent pupillary defect (RAPD, or Marcus Gunn pupil).
The examiner guides the patient to look in 8 directions (up, up and right, right, down and right, down, down and left, left, left and up) with a moving finger, toy , or pen. It is very important not use a dazzling object it will be very uncomfortable for the patient.
it is important to observe for gaze deviation, limitation of movement, disconjugate gaze, or a combination consistent with cranial nerve palsy, orbital disease, or other abnormalities that restrict movement.
Ophthalmoscope (examination of the posterior segment of the eye) can be done directly by using a handheld ophthalmoscope or with a handheld lens in conjunction with the slit lamp biomicroscope.
In-direct ophthalmoscope can be done by using a head-mounted ophthalmoscope with a handheld lens. With handheld ophthalmoscopy, the examiner dials the ophthalmoscope to zero diopters, then increases or decreases the setting until the fundus comes into focus.
The view of the retina is limited with a handheld ophthalmoscope, whereas indirect ophthalmoscopy gives a 3-dimensional view and is better for visualizing the peripheral retina, where retinal detachment most commonly occurs.
The view of the fundus can be improved by dilating the pupils. Before dilation, the anterior chamber depth is estimated because mydriasis can precipitate an attack of acute angle-closure glaucoma if the anterior chamber is shallow.
Depth can be estimated with a slit lamp or less accurately with a penlight held at the temporal limbus parallel to the plane of the iris and pointed toward the nose. If the medial iris is in shadow, the chamber is shallow and dilation should be avoided. Other contraindications to dilation include head trauma, suspicion of a ruptured globe, a narrow angle, and angle-closure glaucoma.
Pupils can be dilated using 1 drop of tropicamide 1%, phenylephrine 2.5%, or both (repeated in 5 to 10 min if necessary); for longer action, a larger dilated pupil, or both, cyclopentolate 1% can be substituted for tropicamide.
Ophthalmoscopy can detect lens or vitreous opacities, assess the optic cup-to-disk ratio, and identify retinal and vascular changes. The optic cup is the central depression, and the optic disk is the entire area of the optic nerve head. The normal ratio of the cup-to-nerve diameters is 0 to 0.4. A ratio of ≥ 0.5 may signify loss of ganglion cells and may be a sign of glaucoma.
Retinal changes include
- Hemorrhage, manifested as small or large areas of blood
- Drusen (small subretinal yellow-white spots that may signify dry age-related macular degeneration)
Vascular changes include
- Arteriovenous nicking, a sign of chronic hypertension in which retinal veins are compressed by arteries where the two cross
- Silver wiring, a sign of hypertension in which thin, fibrotic arteriolar walls decrease the thickness of the light reflex
- Loss of venous pulsations, a sign of increased intracranial pressure in patients known to have had pulsations
A slit lamp focuses the height and width of a beam of light for a precise stereoscopic view of the eyelids, conjunctiva, cornea, anterior chamber, iris, lens, and anterior vitreous. With a handheld condensing lens, it can also be used for detailed examination of the retina and macula.
It is especially useful for the following:
- Identifying corneal foreign bodies and abrasions
- Measuring depth of the anterior chamber
- Detecting cells (RBCs or WBCs) and flare (evidence of protein) in the anterior chamber
- Identifying scleral edema, which is seen as a bowing forward of the slit beam when it is focused beneath the conjunctiva and which is usually a sign of scleritis.
- Identifying diseases such as macular degeneration, diabetic eye disease, preretinal membranes, macular edema, and retinal tears (when using a condensing lens)
Tonometry and gonioscopy, which quantifies the iridocorneal angle and requires the use of a special lens, may be done.
Visual field testing
Visual fields may be impaired by lesions anywhere in the neural visual pathways from the optic nerves to the occipital lobes (see Types of Field Defects and see Figure: Higher visual pathways—lesion sites and corresponding visual field defects.). Glaucoma causes loss of peripheral vision. Fields can be assessed grossly by direct confrontation testing or by more precise, more detailed testing.
In direct confrontation, patients maintain a fixed gaze at the examiner’s eye or nose. The examiner brings a small target (eg, a match or a finger) from the patients’ visual periphery into each of the 4 visual quadrants and asks patients to indicate when they first see the object.
Slowly wiggling the small target helps patients separate and define it. Another method of direct confrontation visual field testing is to hold a number of fingers in each quadrant and ask patients how many they see. For both methods, each eye is tested separately. Abnormalities in target detection should prompt detailed testing with more precise instruments.
More detailed methods include the use of a tangent screen, Goldmann perimeter, or computerized automated perimetry (in which the visual field is mapped out in detail based on patient response to a series of flashing lights in different locations controlled by a standardized computer program). The Amsler grid is used to test the central vision.
Distortion of the grid (metamorphopsia) or a missing area (central scotoma) may indicate disease of the macula (eg, choroidal neovascularization), as occurs in age-related macular degeneration.
Visual Field changes an correlation with Eye disease.
|Altitudinal field defect||Loss of all or part of the superior or inferior half of the visual field; does not cross the horizontal median||More common: Ischemic optic neuropathy, hemibranch retinal artery occlusion, retinal detachment|
Less common: Glaucoma, optic nerve or chiasmal lesion, optic nerve coloboma
|Arcuate scotoma||A small, bow-shaped (arcuate) visual field defect that follows the arcuate pattern of the retinal nerve fibers; does not cross the horizontal median||Damage to ganglion cells that feed into a particular part of the optic nerve head|
More common: Glaucoma
Less common: Ischemic optic neuropathy (usually nonarteritic), optic disk drusen, high myopia
|Binasal field defect (uncommon)||Loss of all or part of the medial half of both visual fields; does not cross the vertical median||More common: Glaucoma, bitemporal retinal disease (eg, retinitis pigmentosa)|
Rare: Bilateral occipital disease, tumor or aneurysm compressing both optic nerves
|Bitemporal hemianopia||Loss of all or part of the lateral half of both visual fields; does not cross the vertical median||More common: Chiasmal lesion (eg, pituitary adenoma, meningioma, craniopharyngioma, aneurysm, glioma)|
Less common: Tilted optic disks
Rare: Nasal retinitis pigmentosa
|Blind-spot enlargement||Enlargement of the normal blind spot at the optic nerve head||Papilledema, optic nerve drusen, optic nerve coloboma, myelinated nerve fibers at the optic disk, drugs, myopic disk with a crescent|
|Central scotoma||A loss of visual function in the middle of the visual field||Macular disease, optic neuropathy (eg, ischemic or Leber hereditary neuropathy, optic neuritis-multiple sclerosis), optic atrophy (eg, due to tumor compressing the nerve or toxic-metabolic disorders)|
Rare: Occipital cortex lesion
|Constriction of the peripheral fields, leaving only a small residual central field||Loss of the outer part of the entire visual field in one or both eyes||Glaucoma, retinitis pigmentosa or another peripheral retinal disorder, chronic papilledema after panretinal photocoagulation, central retinal artery occlusion with cilioretinal artery sparing, bilateral occipital lobe infarction with macular sparing, nonphysiologic vision loss, carcinoma-associated retinopathy|
|Homonymous hemianopia||Loss of part or all of the left half or right half of both visual fields; does not cross the vertical median||Optic tract or lateral geniculate body lesion; lesion in temporal, parietal, or occipital lobe (more commonly, stroke or tumor; less commonly, aneurysm or trauma); migraine (which may cause transient homonymous hemianopia)|
Color vision testing
Twelve to 24 Ishihara color plates, which have colored numbers or symbols hidden in a field of colored dots, are commonly used to test color vision.
Color-blind patients or patients with an acquired color deficiency (eg, in optic nerve diseases) cannot see some or all of the hidden numbers. Most congenital color blindness is red-green; most acquired (eg, caused by glaucoma or optic nerve disease) is blue-yellow.
Tonometry measures intraocular pressure by determining the amount of force needed to indent the cornea. Handheld pen-type tonometers are used for screening.
This test requires topical anesthesia (eg, proparacaine 0.5%). Office-based screening with noncontact air-puff tonometry also can be used; it requires less training because it makes no direct corneal contact. Goldmann applanation tonometry is the most accurate method but requires more training and typically is used only by ophthalmologists.
Measurement of intraocular pressure alone is not adequate screening for glaucoma; the optic nerve also should be examined.
Fluorescein angiography is used to investigate under perfusion and neovascularization in conditions such as diabetes, age-related macular degeneration, retinal vascular occlusion, and ocular inflammation.
It is also useful in preoperative assessment for retinal laser procedures. After IV injection of fluorescein solution, the retinal, choroidal, optic disk, or iris vasculature is photographed in rapid sequence.
Optical coherence tomography
Optical coherence tomography (OCT) provides high-resolution images of posterior eye structures, such as the retina (including retinal pigment epithelium), choroid, and posterior vitreous.
Retinal edema can be identified. OCT works in a manner similar to that of ultrasonography but uses light instead of sound; it does not involve contrast use or ionizing radiation and is noninvasive.
OCT is useful in imaging retinal disorders that cause macular edema or fibrous proliferation over or underneath the macula, including age-related macular degeneration, diabetic edema, macular holes, and epiretinal membranes. It is also useful for monitoring progression of glaucoma.
What is the difference between the direct and indirect ophthalmoscope, many thanks for our student Jameel Hijazeen who made a beautiful table :
|Direct Ophthalmoscopy||Indirect ophthalmoscopy|
|Magnification||About 15 times||5 times when a +13D condensing lens is used|
|Diameter of the field of observationview||Smaller (about 10o in diameter)||Wider (about 37o in diameter)|
|Brightness||There is relatively low brightness||There is relatively greater brightness|
|Structures seen||Central retina only||Peripheral retina seen (by using a scleral depressor in addition to the indirect ophthalmoscopy itself)|
|Image of the fundus that is seen||Virtual & erect image||Real & inverted image|
|Stereopsis||Image formed is not stereoscopic||Binocular indirect ophthalmoscopy provides better stereopsis|
|Retina anterior to the equator||Not well seen (seen with difficulty)||Seen better|
|Scleral indentation||Difficult||Can be easily done in binocular indirect ophthalmoscopy|
|Visualization in hazy media||Poor||Better|
good examples of seminars