SCREENING TESTS FOR EYES

ANATOMY OF THE EYERoumel E. Litao, M.D.

A. OrbitB. EyeballC. Extraocular musclesD. Ocular adnexaeE. Optic nerveOrbitPear-shaped with the optic nerve as its stemVolume: 30 cc20% of the space occupied by the eye7 Bones of the OrbitFrontal boneZygomaMaxillaryPalatineLacrimalEthmoidalSphenoid

Orbital WallsRoof: frontal bone, sphenoid boneLateral Wall: sphenoid bone, zygomatic boneFloor: maxillary bone, zygomatic boneMedial Wall: ethmoid, lacrimal bone, frontal bone, maxillary bone- Relationship to SinusesFrontal sinus: aboveMaxillary sinus: belowEthmoid & sphenoid sinuses: medialOrbit

Orbital ApexEntry site of all the nerves & blood vessels to the eye and all the extraocular muscles except the inferior obliqueOrbital Apex

Blood SupplyArterial Supply: ophthalmic artery (branch of internal carotid artery)Central retinal arteryLacrimal artery: lacrimal gland & upper eyelidMuscular branches to the musclesLong posterior ciliary arteries: ciliary bodyShort posterior ciliary arteries: choroid & part of the optic nerveMedial palpebral arteries: eyelidsBlood SupplyVenous DrainageSuperior & Inferior ophthalmic veinsThese veins communicate with the cavernous sinusThe skin of the periorbital region drain to the angular vein and to the superior ophthalmic veinSo, there is a direct communication between the skin of the face & the cavernous sinusEyeballConjunctiva: thin, transparent mucous membranePalpebral conjunctiva: lines the posterior surface of the eyelid & adherent to the tarsusBulbar conjunctiva: covers the eyeball; loosely adherent to the orbital septum in the fornices & is folded many timesSemilunar fold: thickened fold at the inner canthus & corresponds to the nictitating membrane of lower animalsLayers of the ConjunctivaConjunctival epitheliumcontains goblet cellsConjunctival stromacontains the accessory lacrimal glands of Krause and WolfringTenons CapsuleFibrous membrane covering the globe from the limbus to the optic nerveScleraFibrous outer layer of the eye made up of collagenThinnest (0.3 mm) at the insertion of recti muscles, elsewhere it is 0.6 mm thickEpiscleraThin layer of fine elastic tissue which contains blood vessels that nourish the scleraEyeball

CorneaTransparent tissue inserted to the sclera at the limbusThicker at the periphery (0.65 mm) than at the center (0.52 mm)Horizontal diameter: 11.75 mmVertical diameter: 10.6 mm5 Layers of the CorneaEpithelium: 5-6 layers of cellsBowmans membrane: clear acellular layerStroma: 90% of corneal thicknessIntertwining lamellae of collagen fibrils that are parallel to each otherDescemets membrane: basal lamina of corneal endotheliumEndothelium: single layer of cells which act as a pumpCornea gets its nutrition from:Limbal vesselsAqueousTearsSensory nerves come from CN V1.Transparency of the CorneaUniform structureAvascularityDeturgescenceCornea

Uveal TractIrisCiliary bodyChoroidIrisFlat surface with central opening pupilLayers of the iris:Stroma: contains the sphincter and dilator musclesPigmented posterior layersCiliary BodyConsists of 2 zones:Pars plicata: 2 mm wide & from which arise ciliary processes which produce the aqueousPars plana: 4 mm flattened posterior zoneMuscles of the Ciliary BodyCircular fibers: responsible for accommodationLongitudinal fibers: insert to the trabecular meshwork altering the pore sizeRadial fibersChoroidPosterior portion of uveal tract located between the retina and scleraChoriocapillaries: internal portion of choroid which nourishes the outer retinaUveal Tract

LensBiconvex, avascular, clear4 mm thick & 9 mm in diameterLocated behind the iris & connected to the ciliary body by the zonulesHas a semi permeable lens capsule (to water & electrolytes)Consists of 65% water & 35% protein and mineralsHas subepithelial lamellar fibers continuously produced making the lens larger & less elastic with age.

AqueousClear fluid that fills the anterior and posterior chambers of the eyeComposition similar to plasma but with higher amount of ascorbate, pyruvate; lactate, and lower amount of protein, urea and glucoseVolume: 230 uLRate of production: 2.5 uL/minAnterior Chamber AngleJunction of the peripheral cornea & the root of the irisMain structures:Schwalbes Line: corresponds to termination of the corneal endotheliumTrabecular Meshwork: perforated sheets of collagen & elastic tissueScleral Spur: inward extension of sclera in which the ciliary body & iris are attachedAnterior Chamber Angle

RetinaMulti-layered sheet of neural tissue0.1 mm thick at the ora serrata and 0.56 mm thick at the posterior poleMaculaCenter of posterior retinaSeen clinically as 3 mm yellowish pigmentation to xantophyll pigmentsFoveaCenter of maculaSeen as depression and called foveal reflexFoveolaCenter of the foveaThinnest part of the retinaPhotoreceptors are all cones

10 Layers of the RetinaInternal limiting membraneNerve fiber layer: ganglion cell axons going to optic nerveGanglion cell layerInner plexiform layer: connections of ganglion cells with the amacrine and bipolar cellsInner nuclear layer: cell bodies of amacrine, bipolar, and horizontal cellsOuter plexiform layer: connections of these cells to the photoreceptorsOuter nuclear layer: cell nuclei of photoreceptorsExternal limiting membranePhotoreceptor layer: rods and cones inner and outer segmentsRetinal pigment epithelium

Layers of Retina

Blood Supply of the RetinaChoriocapillaries: supply the outer third of retina from outer plexiform layer to RPECentral retinal artery: supplies the inner 2/3 of the retinaVitreousclear, avascular body99% water, 1% collagen and hyaluronic acid2/3 of the volume and weight of the eyeExtraocular MusclesMedial RectusAdductionCN IIILateral RectusAbductionCN VISuperior RectusElevationIntorsion, Adduction, CN IIIInterior RectusDepressionExtorsion, Adduction, CN III

Superior ObliqueIntorsionDepression, Abduction, CN IVInterior ObliqueExtorsionElevation, Abduction, CN III

Ocular AdnexaeEyelids LayersSkinOrbicularis Oculi CN VIIAreolar tissueTarsal platesPalpebral conjunctiva

Lid RetractorsMuscles that open the eyelidsUpper LidLevator palpebrae superiorisMullers muscleLower LidInferior rectus muscleInferior tarsal muscle

Lacrimal ComplexLacrimal gland w/ orbital and palbebral portionAccessory lacrimal glands of Krause and WolfringCanaliculiLacrimal sacNasolacrimal ductLacrimal Complex

Optic NerveIntraocular portion: optic nerve head; 1.5 mm in diameterOrbital portion: 25-30 mm long; 3 mm in diameterIntracanalicular portion: 4-9 mm longIntracranial portion: 10 mm longFibers of the Optic NerveVisual fibers: 80%Pupillary fibers: 20%Optic Nerve

50Cranial Nerves III, IV, and VI

III - OculomotorIV - TrochlearVI - Abducens

III (Oculomotor) innervates:

1) Medial rectus2) Superior rectus3) Inferior rectus4) Inferior oblique

Levator palpebrae supPupillary sphincterCiliary muscle

IV (Trochlear) innervates:

Superior oblique

VI (Abducens) innervates

Lateral rectus.

Proprioceptive info from eye muscles

comes through Trigeminal nerve.

RISK FACTORAGEChildren and newborns suffer from eye diseases very rarely and most of the patients exceed 40 years of age. Due to ageing of the trabecular meshwork intraocular pressure rises even in healthy people. In advanced age not only the number of risk factors increases but also the loss of nerve fibers occurs. The number of people with higher eye pressure increases with age and because the average life duration rises we should not ignore this fact.

genderIn spite of the fact that women and men have usually the same values of intraocular pressure, women are more affected by eye diseases than men. One of possible explanations is that women have more sensitive papillae of the optic nerve. Sex hormones play an important role in regulation of intraocular pressure. Intraocular pressure usually decreases during pregnancy and on the other hand increases during menopause.

Poor Nutrition (Low Vitamin A Intake)

Lack of Vitamin A causes degenerating night vision which can, in serious cases, lead to total blindness. It is most common amongst pregnant women and preschool aged children in developing countries.heredityPeople with a family history of eye diseases have greater chance of developing it.Eye injuriesInjury to the eye may cause further eye diseases. This can occur immediately after the injury or years later.Blunt injuries that bruise the eye (called blunt trauma) or injuries that penetrate the eye can damage the eyes drainage system.Cigarette smokingStudies have shown that smokers and former smokers at least double their risk of developing eye diseases compared to non-smokers. Alcohol useYour overall visual performance may be altered since drinking heavily impairs brain function. You may have blurred vision or double vision due to weakened eye muscle coordination. You may also experience delayed reactions while driving. Alcohol tends to affect the speed at which your iris constricts and dilates. A driver that has been drinking alcohol cannot adapt as quickly to oncoming headlights. Drinking alcohol has also been shown to decrease the sensitivity of your peripheral vision. This may give you the effect or perception of having tunnel vision.

Possible risk factorsHigh Blood PressureAbdominal ObesityUse of Beta BlockersHigh blood pressureAlong with causing heart and kidney problems, untreated high blood pressure can also affect your eyesight and lead to eye disease. Hypertension can cause damage to the blood vessels in the retina, the area at the back of the eye where images focus. This eye disease is known as hypertensive retinopathy. The damage can be serious if hypertension is not treated.Abdominal obesityAbdominal fat releases estrogen and other chemicals that may contribute to inflammation associated eye diseases.USE OF BETA BLOCKERSBeta Blockers decreases intraocular pressureSCREENING TESTS FOR EYES68OCULAR HISTORY

Taking an ocular historyWhat does the patient perceive to be the problem?Is visual acuity diminished?Does the patient experienced blurred, double, or distorted vision?Is there pain; is it sharp or dull; is it worse when blinking?Is the discomfort an itching sensation or more of a foreign body sensation?Are both eyes affected?Is there a history of discharge? If so, inquire about color, consiustency, odor.What is the duration of the problem?Is this a recurrence of a previous condition?How has the patient self-treated?What makes the symptoms improve or worsen?Has the condition affected performance of activities of daily living?Are there any systemic diseases? What medications are used in their treatament?Whaht concurrent opthalmic conditions does the patient have?Is there an opthalmic surgery history?Have other family members had the same symptoms or condition?

EXTERNAL EYE EXAMINATION

Commonly, the upper 2 mm of the iris are covered by the upper eyelid. The patient is examined for ptosis and for lid retraction. Sometimes the upper eyelid turns out, affecting the closure. The lid margins and lashes should have no edema, erythema, or lesions. The examiner looks for scaling or crusting, and the sclera is inspected. The normal sclera is opaque and white. Lesions on the conjunctiva, discharge, and tearing or blinking are noted. The room should be be darkened so that the pupils can be examined. The pupillary response is checked with a penlight to determine if the pupils are equally reactive and regular. A normal pupil is black. An irregular pupil may result from trauma, previous surgery, or a disease process. The patient eyes are observed in primary or direct gaze, and any head tilt is noted. A tilt may indicate cranial nerve palsy. The patient is asked to stare at a target; each eye is covered and uncovered quickly while the examiner looks for any shift in gaze. The examiner observes for nystagmus. The extra ocular movements of the eyes are tested by having the patients follow the examiners finger, pencil or a hand light through the six cardinal directions of gaze ( up, down,right,left,and both diagonals). This is especially important when screening patients for ocular trauma or for neurologic disorders.

VISUAL ACUITYVisual acuity(VA) is acuteness or clearness ofvision, which is dependent on the sharpness of the retinal focus within theeyeand the sensitivity of the interpretative faculty of the brain.[1]Visual acuity is a measure of the spatial resolution of the visual processing system. VA is tested by requiring the person whose vision is being tested to identify characters (like letters and numbers) on a chart from a set distance. Chart characters are represented as black symbols against a white background (for maximumcontrast). The distance between the person's eyes and the testing chart is set at a sufficient distance to approximateinfinityin the way thelensattempts to focus. Twenty feet, or six metres, is essentially infinity from an optical perspective.

Determination of visual acuityMeasure of visual acuity tests Cranial Nerve II, is a measureof central visionmeasures how well you see at various distances. It is the familiar eye charttest.

1.Snellenchart-has number atthe end ofeach lineof letters indicates thedegreeofvisualacuitywhenmeasuredatadistanceof20feet.Thenumerator 20is thedistance in feet between thechart andthe client. Thedenominator 20 is the distance from which the normal eye can read thelettering, which correspond to the number at the end of each letter line;therefore the larger the denominator the poorer the vision.

SNELLEN CHART

NOTE:20/20 vision is a term used to express normal visual acuity (the clarity or sharpness of vision) measured at a distance of 20 feet.If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance.If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet.1 Secure the Snellen chart to a flat surface in a well-lit room. The chart should be at a comfortable height, which may change depending on the individual's height.2 Measure twenty feet from the chart and mark a spot facing the chart directly. (The test results will only be accurate if it is taken from this distance.)3 Stand at the twenty foot line and cover your left eye, so you can only see out of your right eye. Starting from the top, read each row from left to right for as far down as you can still make out the letters. Note the last line on which you could correctly identify every letter. Have an assistant verify that you are reading the letters correctly.

4 Repeat the test with your left eye, covering your right eye this time. Note the last row you could read with complete accuracy. The row for each eye will not necessarily be the same.5 Take note of the fraction shown to the left of each row: It identifies how your vision rates. For example, if you could read to the fifth line, you have 20/40 vision; if you could read to the seventh line, you have 20/25 vision.6 Look at your results to determine the quality of your eyesight. For example, someone with 20/60 vision can read at 20 feet away what a person with normal vision could read at 60 feet away. In the United States, a score of 20/40 or better is required to drive a car without corrective lenses, vision of 20/200 or worse qualifies an individual as legally blind.

Ishihara Plate

The test consists of a number of colored plates, called Ishihara plates, each of which contains a circle of dots appearing randomized in color and size. Within the pattern are dots which form a number or shape clearly visible to those with normal color vision, and invisible, or difficult to see, to those with a red-green color vision defect, or the other way around. The full test consists of 38 plates, but the existence of a deficiency is usually clear after a few plates. There is also the smaller test consisting only 24 plates.Plates 1 17 each contain a number, plates 18 24 contain one or two wiggly lines. To pass each test you must identify the correct number, or The plates make up several different test designs:Transformation plates: individuals with color vision defect should see a different figure from individuals with normal color vision.Vanishing plates: only individuals with normal color vision could recognize the figure.Hidden digit plates: only individuals with color vision defect could recognize the figure.Diagnostic plates: intended to determine the type of color vision defect (protanopia or deuteranopia) and the severity of it.Cover-uncover testA cover test is an objective determination of the presence and amount of ocular deviation. It is typically performed by orthoptists, ophthalmologists and optemetrists during eye examination.The two primary types of cover tests are the alternating cover test and the unilateral cover test (cover-uncover test).The test involves having the child (typically) focusing on a near object. A cover is placed over an eye for a short moment then removed while observing both eyes for movement. The "lazy eye" will wander inwards or outwards, as it begins to favour its perceptive visual preference. The process is repeated on both eyes and then with the child focusing on a distant object.

The cover test is used to determine both the type of ocular deviation and measure the amount of deviation. The two primary types of ocular deviations are the tropia, also known as Strabismus, and the phoria. A tropia is a constant misalignment of the visual axes of the two eyes, i.e. they can't point the same direction. A phoria is a latent deviation that only appears when fixation is broken and the two eyes are no longer looking at the same object.

The unilateral cover test is performed by having the patient focus on an object then covering the fixating eye and observing the movement of the other eye. If the eye was esotropic, covering the fixating eye will cause an outwards deviation and vice versa. The alternating cover test, or cross cover test is used to detect heterophoria, where direct cover test will be normal for both eyes.

RELEVANT INFORMATIONTypes of BlindnessGlobally, it is estimated that there are 38 million persons who are blind. Moreover, a further 110 million people have low vision and are at great risk of becoming blind. The main causes of blindness and low vision are cataract, trachoma, glaucoma, onchocerciasis, and xerophthalmiaTypes of Blindness: Cataract, Trachoma, GlaucomaCataracts, the world's leading cause of blindness, are an enormous public health problem in both developing and industrialized countries.

Trachoma is still a widespread disease that causesblindness in many developing countries, particularlyamong rural populations.

Glaucoma is the second leading cause of vision loss in the world.Types of Blindness:

ONCHOCERCIASISAn estimated 17.7 million persons, most of them in Africa, are infected with the parasite Onchocerca volvulus. Onchocerciasis has caused blindness in 270,000 and left another 500,000 with severe visual impairment. Onchocerciasis also can cause disfiguring skin changes, musculoskeletal complaints, weight loss, changes in immune function, epilepsy, and growth arrest.

XEROPHTHALMIAVitamin A deficiency remains a major cause of pediatric ocular morbidity. Over five million children develop xerophthalmia annually, a quarter million or more becoming blind.

Assessment of the Eyes

Eye assessmentShould be carried out in anorderly fashion

Moving from the extraocular to the intraocularstructures

Usually includes testing of associated cranial nerves & can be performed in the following order:1.Determination ofVisualAcuity2.Assessment of external eye & lacrimal apparatus3.Evaluation of extraocular muscle function4.Assessment of anterior segment structures5.Assessment of posterior segment structures

PlanningPlace client in well lighted room

Nurse must be able to control natural and overhead lighting during some portionsof the examination

Implementation.Explain procedure. Discuss how results will be used in planning further careWash hands andapply glovesProvide privacyInquire history

Assessment of External Eye and Lacrimal ApparatusExternal examination of eyes consists of:1.inspection ofthe eyelids,surrounding tissues and palpebralfissure.2.Palpation oftheorbitalrimmay also bedesirable,dependingon thepresenting signs and symptoms.3.The conjunctiva and sclera can be inspected byhaving the individual look up, and shining a light while retracting the upper orlower eyelid.4.The cornea and iris may be similarly inspected

Assessment of External Eye and Lacrimal Apparatus1. Inspect theeyelids for position andsymmetry.

2. Palpate the eyelids for the lacrimal glands.-a.To examine thelacrimalgland, theexaminer, lightlyslide thepadofthe index finger against the clients upper orbital rim.-b. Inquire for any pain ortenderness.3. Palpate for the nasolacrimal duct to check for obstruction.a. To assess the nasolacrimal duct, the examiner presses with the index finger against the clients lower inner orbital rim, at thelacrimal sac, NOT AGAINST THE NOSE.b. In the presenceof blockage, this will cause regurgitation of fluid in the punctaNormal Findings: Eyelids Upper eyelids cover the small portion of the iris, cornea, and sclera when eyes are open. No PTOSIS noted. (drooping of upper eyelids). Meets completely when eyes are closed. Symmetrical.

Lacrimal Apparatus Lacrimal gland is normally non palpable. No tenderness on palpation. No regurgitation from the nasolacrimal duct

Evaluation of Extraocular functionThis test is an examination of the function of the eye muscles. A doctor observes the movement of the eyes in six specific directions.Client are asked to sit or stand with your head erect and a forward gaze. Nurse will hold a pen or other object 12 inches in front of your face. Nurse will then move the object in several directions and ask client to follow it their eyes, without moving their head.Normal Results-Normal movement of the eyes in alldirections.

What Abnormal Results Mean-Eye movement disorders may be due to abnormalities of the muscles themselves orproblems in the sections of the brain thatcontrol these muscles.Assessment of the Anterior StructuresThe anterior segment is the front third of the eye that includes the structures in front of the vitreous humor: the cornea,iris, ciliary body, and lens

Assessment of Eye StructureImplementation1.Explain procedure. Discuss how results willbe used in planning furthercare2.Wash hands and applygloves3.Provideprivacy4.Inquirehistory

Eyebrows (hair and skin quality)Normal findings:Hair evenly distributed, skin intactSymmetrical eyebrows w/ equal movements

Deviations from Normal:Loss of hair, scaling/flakiness of skinUnequal alignment / movement of eyebrows

EyelashesNormal Findings:Equally distributed, curled slightly outwardDeviations:Lashes turned inward

EyelidsNormal Findings:Skin intact, no discharge, no discolorationLids close symmetricallyApprox. 15-20 involuntary blinks/minute, bilateral blinkingWhen lids open, no visible sclera above corneas. Upper/lower borders ofcornea are slightly covered

Deviations:Redness, swelling, flaking, crusting, discharge nodules/lesionsLids closeasymmetrically, incompletelyor painfullyInfrequent blinkingPtosis, ectropion lower lids rolled out) or entropion (lower lids rolled in), rimof sclera visible between lid andiris

Bulbar conjunctiva-retract eyelids, -exert pressure over upper & lower bony orbits and ask client to look up & down & sidewaysNormal Findings:Transparent, sclera appears white (yellowish in dark skinned)

Deviations from Normal:Jaundicedsclera(liverdis),excessivelypalesclera,lesions/nodules(mechanical, chemical, allergic or bacterial damage)

Palpebral Conjunctiva- Evert & retract both lower lids & ask client to look up.Normal Findings:Shiny, smoothand pink/redDeviations from Normal:Extremely pale (anemia), red (inflammation), nodules or lesions

Lacrimal Gland-inspect and palpateNormal Findings:No swelling /tenderness over lacrimal glandDeviations from Normal:swelling /tenderness over lacrimal gland

Lacrimal sac and nasolacrimal duct- inspect & palpateNormal Findings:No edema & tearingDeviations from Normal:Increased tearing, regurgitation of fluid on palpation of lacrimal sac

Cornea1. Inspection: Ask client to look straight, hold penlight at oblique angle of eye &move light slowly across corneal surface.Normal Findings:Shiny, smooth. Details ofiris are visibleArcus senilis (grayish w/ white ring around margin in older persons

Diagnostic/ Laboratory Examinations for Disturbances in Visual Perception

Ophthalmoscopy

(funduscopyorfundoscopy) is a test that allows a health professional to see inside thefundus of the eyeand other structures using anophthalmoscope(orfunduscope). It is done as part of aneye examinationand may be done as part of a routinephysical examination. It is crucial in determining the health of theretinaand thevitreous humor.

It is of two major types:Direct Ophthalmoscopyone that produces an upright, or unreversed, image of approximately 15 times magnification.Indirect Ophthalmoscopyone that produces an inverted, or reversed, direct image of 2 to 5 times magnification.

Disturance(s)CataractGlaucomaRetinal Detachment

TheSlit Lampis an instrument consisting of a high-intensity lightsource that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with abiomicroscope. The lamp facilitates an examination of theanterior segment, or frontal structures andposterior segment, of thehuman eye, which includes theeyelid,sclera,conjunctiva,iris, naturalcrystalline lens, andcornea. The binocular slit-lamp examination provides a stereoscopic magnified view of the eye structures I detail, enabling anatomical diagnoses to be made for a variety of eye conditions. A second, hand-held lens is used to examine theretina.

Disturance(s)Retinal DetachmentCataractColor Fundus Photography

Is used to detect and document retinal lesions. The patients pupil are widely dilated before the procedure.

UltrasonographyIn ultrasonography, or ultrasound, high-frequency sound waves, inaudible to the human ear, are transmitted through body tissues. The echoes are recorded and transformed into video or photographic images.

Optical Coherence Tomography (OCT)is an optical signal acquisition and processing method.It capturesmicrometer-resolution, three-dimensional images from withinoptical scatteringmedia (e.g., biological tissue). Optical coherence tomography is aninterferometrictechnique, typically employingnear-infraredlight. . The use of relatively longwavelengthlight allows it to penetrate into the scattering medium.Confocal microscopy, another similar technique, typically penetrates less deeply into the sample.

Disturance(s)Retinopathy

Tonometryis the procedureeye care professionalsperform to determine theintraocular pressure(IOP), the fluidpressureinside theeye. It is an important test in the evaluation of patients at risk fromglaucoma. Most tonometers are calibrated to measure pressure in millimeters of mercury (mmHg).

Disturance(s)CataractGlaucomaIndocyanine Green Angiography a diagnostic test that involves taking photographs of the blood vessels in the eye with the help of a contrast dye. Indocyanine is a green dye that works with infrared light and is visualized with a special camera. The images produced by this test help doctors evaluate the retina and diagnose or monitor problems such as macular degeneration, abnormal vessel growth, macular edema, certain

Perimetry Test (Visual Field Testing) for GlaucomaA perimetry test (visual field test) measures all areas of youreyesight, including your side, or peripheral, vision

Disturance(s)GlaucomaFundus Photography(also calledfundography[1]) is the creation of aphotographof the interior surface of theeye, including theretina,optic disc,macula, andposterior pole(i.e. thefundus

Disturance(s)Retinal DetachmentOphthalmic RadiographyIts using radiation to generate a picture of the eye. Similar to what an MRI is, but on the eye instead of the head/brain. Canon appears to be the major manufacturer ofOphthalmic Radiography equipment.

MRI scan

MRI (magnetic resonance imaging) is a fairly new technique that has been used since the beginning of the 1980s.The MRI scaner uses magnetic and radio waves to create pictures of tissues, organs and other structures within the body, which can then be viewed on a computer

Electroretinographymeasures the electrical responses of various cell types in theretina, including thephotoreceptors(rodsandcones), inner retinal cells (bipolarandamacrinecells), and theganglion cells

Ophthalmodynamometrydetermination of the blood pressure in the retinal artery.

IntravenousFluoresceinangiography(IVFA)orfluorescent angiographyis a technique for examining the circulation of theretinaandchoroidusing a fluorescent dye and a specialized camera. It involves injection of sodiumfluorescein[1]into the systemic circulation, and then anangiogramis obtained by photographing thefluorescenceemitted after illumination of the retina with blue light at awavelengthof 490nanometers. The test uses thedye tracingmethod.

Disturance(s)Retinal DetachmentRetinopathyElectronystagmography(ENG) is a diagnostic test to record involuntary movements of the eye caused by a condition known asnystagmus. It can also be used to diagnose the cause ofvertigo,dizzinessorbalancedysfunction by testing thevestibular system.