8-Part Eye Examination
BLOCK 20 MODULE 01
Ophthalmologists
SUMMARY/OUTLINE
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Distance Acuity Test
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External Exam
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Pupillary Exam
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Motility Exam
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Visual Fields (Confrontation Test)
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Tonometry
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Ophthalmoscopy
VIII.
Slit-lamp Biomicroscopy
DISTANCE VISUAL ACUITY Ask the patient to stand or sit at a designated testing distance (20 feet) Occlude the left eye (testing one eye at a time) Ask the patient to identify each letter in the chart, on the lines of successively smaller optotypes, until patient correctly identifies only half the optotypes on a line Note the corresponding acuity measurement shown at the line of the chart Repeat above steps for the left eye, with the right eye covered Retest acuity with the patients with low vision, e.g. counting fingers, hand motion, light perception, etc.
In using the snellen’s chart, place the patient 20 feet away from the chart. Remember to test each eye separately and be tested with and without corrective lenses But in some clinics, there is only limited space, so they minimize the distance by converting them to smaller distances. The largest letter E is equivalent to 20/200. If the patient cannot read the letter E, move the patient 5 feet closer until the patient reaches 5 feet away. Note the distance where the patient is able to read the letter E. If the patient still cannot read at 5 feet, proceed to counting finger test. Some clinics may use meters. Patients usually placed 6 meters away from the chart.
Visual acuity is scored as a fraction (eg, “20/40”). The first number represents the testing distance between the chart and the patient, and the second number represents the smallest row of letters that the patient’s eye can read. Hence normal vision is 20/20 and 20/60 acuity indicates that the patient’s eye can only read from 20 feet letters large enough for a normal eye to read from 60 feet. th
Vaugn Asbury’s General Ophthalmology 39 Edition
For pediatric patients, you can use figures or the tumbling E charts
Visual acuity can be tested either for distance or near, conventionally at 20 feet (6 meters) and 14 inches (33 cms) away, respectively, but distance acuity is the general standard for comparison. For diagnostic purposes visual acuity is always tested separately for each eye, whereas binocular visual acuity is useful for assessing functional vision, such as for assessing the eligibility to drive. th
Vaugn Asbury’s General Ophthalmology 39 Edition SNELLEN’S CHART
Other patients can use the Jaeger chart. the patient is scored depending on which line of sentences he can read. J10 is the biggest and J1 is the normal acuity. acuity.
Distance visual acuity test should be the first thing to do during the 8 part eye exam. You should do this before palpating, or putting any eye medication me dication or drugs so that visual acuity is not altered because of the prior tests administered. Page 1 of 11
Example result
With correction FAR SIGHT OS 20/150 OD 20/300 NEAR SIGHT OS J8 OD J10
Without correction
20/20 20/20
J1 J1
COUNTING FINGERS By convention, ophthalmologists test first the right eye. If it is known that the other eye is “buron” maybe the patient complained of it before assessment, check the “buron” eye first. In counting fingers, place your finger 1 ft away from the patient and let the patient count the fingers you are showing to him. If the patient cannot count at 1 feet away, move 1 more feet away until you reach the maximum of 3 feet. Record the distance where the patient can count the fingers shown to him. After the maximum of 3 feet and the patient cannot count the fingers, proceed to light perception test. HAND MOTION TEST Make sure that you move your hands against the light. LIGHT PERCEPTION TEST Make sure to turn off the lights The patient unable to read the largest (“20/200”) letter on a Snellen chart should be moved closer to the chart until that letter can be read. The distance from the chart is then recorded as the first number. Visual acuity of “5/200” means that the patient can identify correctly the largest letter from a distance of 5 feet but not further away. An eye unable to read any letters is tested by the ability to count fingers. “CF at 2 ft” indicates that the eye was able to count fingers held 2 feet away but not farther away. If counting fingers is not possible, the eye may be able to detect a hand moving vertically or horizontally (“HM,” or “hand motions” vision). The next lower level of vision would be the ability to perceive light (“LP,” or “light perception”). An eye that is totally blind is recorded as having no light perception (“NLP”). th
Vaugn Asbury’s General Ophthalmology 39 Edition
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EXTERNAL EXAMINATION Observe the facial skin for any dermal or vascular changes; note any lesions or evidence of trauma Note any significant asymmetry of facial bones Note the lid position; assess effectiveness of eyelid closure and strength of the orbicularis muscles if appropriate Palpate the bony orbit for any lesion or deformity
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This is performed before studying the eye under magnification Gross inspection and palpation: lesions, growth, inflammatory signs (swelling, erythema, warmth, tenderness) Check for the ff: position of eyelids (ptosis, lid retraction) o asymmetry can be quantified by measuring the o central width (in mm) of palpebral fissure (space bet lower and upper lid margins) abnormal motor fxn of the lids (upper lid elevation, o forceful lid closure) may be due to neurologic or primary muscular abnormalities o malposition of the globe (proptosis) that may occur in orbital disease o bony orbital rim and periocular soft tissue General facial evaluation: enlarged preauricular LN, sinus tenderness, temporal o artery prominence, skin/mucous membrane abnormalities You canauscultate for bruit at the temporal side of o the orbit or directly at the globe. This can help you detect carotid sinus fistula
PUPILLARY EXAMINATION Turn off the light to decrease the room illumination Ask the patient to maintain fixation on a distance target Shine a bright handheld light directly into the right eye by approaching it from the side or from below Record the direct pupillary response to light in the right eye in terms of briskness of the response; observe the consensual reflex by noting the response to light of the non-illuminated pupil Repeat above steps for the left eye Enumerate the steps in performing the swinging flash light test and explain the clinical significance of relative afferent papillary defect (Marcus Gunn pupil)
Assessment of pupil function should be done before any drops are instilled in the eye and before the cornea is touched (eg, applanation tension or Schirmer test). Examination of the pupils with a light stimulus provides evidence of the health of both the afferent and efferent systems. In addition to light, the pupils also respond to accommodation and convergence for clear and single vision at near. The pupils will constrict equally when either accommodation or convergence is stimulated by a near object. When all 3 actions —accommodation, convergence, and miosis—occur simultaneously, this is called the synkinetic near response. Pupil function is evaluated with a bright penlight or other intense, small light in a dimly illuminated room. Pupil or iris abnormalities found with the naked eye can then be more thoroughly evaluated using the biomicroscope. The pupils are Page 2 of 11
evaluated for size, shape, direct light response, consensual response, and near response. SIZE In dim illumination, the average pupil diameter is 3 or 4 mm. This is ascertained by shining the light from below the patient’s nose so that the pupils are just visible to the examiner; the light is not shone directly into the patient’s eye. Pupils smaller than 2 mm are said to be miotic; pupils larger than 6 mm are mydriatic. Miotic pupils may be caused by antiglaucoma medications, chronic iris inflammation, age, or a neurologic disorder. Abnormal mydriasis is caused by certain drugs, neurologic disorders, iris injury, or acute glaucoma. The pupils should be equal in size , although a small difference (1 mm) may be a normal variation. I f they are unequal ( anisocoria), the difference between them should be further evaluated in both dark and bright room illumination.
stimulation of the right eye. As the light is swung from the right to the left eye, both pupils will begin to dilate normally as the light is moved away from the right eye and then not constrict or paradoxically widen as the light is shone into the left eye (since the direct response in the left eye and the consensual response in the right eye are reduced compared to the consensual response in the left eye and direct response in the right eye from stimulation of the right eye). When the light is swung back to the right eye, both pupils will begin to dilate as the light is moved away from the left eye and then constrict normally as the light is shone into the right eye. This phenomenon is called a relative afferent pupillary defect (RAPD). th
Vaugn Asbury’s General Ophthalmology 39 Edition
SHAPE Both pupils should be round. The pupils are normally centered or a little nasal in the iris. An eccentric pupil may be the result of faulty embryonic development, injury, intraocular surgery, or inflammation. In addition to being eccentric, a pupil may also have an unusual shape. DIRECT LIGHT RESPONSE In dim room illumination, the patient is instructed to look at a distant target (this prevents the pupillary response to a near stimulus). The light source is presented to each eye separately and slightly off center to avoid the near response. Each pupil should exhibit a brisk response and constrict to about 2 mm. CONSENSUAL RESPONSE The consensual response is the simultaneous and equal response of one pupil when the other pupil is being stimulated by direct illumination or a near target. If the stimulated pupil constricts normally, then the consensual response of the other pupil will produce equal constriction without direct light stimulus. The pupils should be symmetric, and each one should be examined for size, shape (circular or irregular), and reactivity to both light and accommodation. Pupillary abnormalities may be due to (1) neurologic disease, (2) intraocular inflammation causing either spasm of the pupillary sphincter or adhesions of the iris to the lens (posterior synechiae), (3) markedly elevated intraocular pressure causing atony of the pupillary sphincter, (4) prior surgical alteration, (5) the effect of systemic or eye medications, and (6) benign variations of normal.
SWINGING PENLIGHT TEST FOR MARCUS GUNN PUPIL As a light is swung back and forth in front of the two pupils, one can compare the reactions to stimulation of each eye, which should be equal. If the neural response to stimulation of the left eye is impaired, the pupil response in both eyes will be reduced on stimulation of the left eye compared to
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MOTILITY EXAMINATION Sit facing the patient. Hold finger on or small fixation target at eye level about 10-14 inches in front of the patient, with the patient looking straight ahead. Ask the patient to follow the target as you move it into the six cardinal fields and up and down along the midline. Elevate the upper eyelid with a finger on your free to observe downgaze Note whether the amplitude of eye movement is normal or abnormal in both eyes Note any nystagmus that may be present Determine alignment using the Hirschberg method of corneal light reflection test – hold a penlight in front of the patient eyes at a distance of approximately 2 feet, directing the light at the midpoint between the two eyes of the patient; instruct the patient to look directly at the light; compare the position of the two corneal light reflections and record the estimated result
The extraocular muscles include: the medial, inferior, and superior recti, the inferior oblique, and levator palpebrae muscles, all innervated by the oculomotor nerve (III); the superior oblique muscle, innervated by the trochlear nerve (IV); and the lateral rectus muscle, innervated by the abducens nerve (VI). The precise action of any muscle depends on the orientation of the eye in the orbit and the influence of the orbital Page 3 of 11
connective tissues, which regulates the direction of action of the extraocular muscles by acting as their functional mechanical origins (the active pulley hypothesis).
Mnemonic: " SO-4,
LR-6, All the rest 3" (ie Superior Oblique by CN 4, Lateral rectus by CN 6, and all the other EOMs by CN 3).
TESTING OF THE VISUAL FIELD The patient is asked to follow a target with both eyes as it is moved in each of the four cardinal directions of gaze. The examiner notes the speed, smoothness, range, and symmetry of movements and observes for unsteadiness of fixation (eg, nystagmus). Impairment of eye movements can be due to neurologic problems (eg, cranial nerve palsy), primary extraocular muscular weakness (eg, myasthenia gravis), or mechanical constraints within the orbit limiting rotation of the globe (eg, orbital floor fracture with entrapment of the inferior rectus muscle). Deviation of ocular alignment that is the same amount in all directions of gaze is called “comitant.” It is “incomitant” if the amount of deviation varies with the direction of gaze.
Landmarks to remember: 0mm Light reflection is at the center of the pupil 1mm Light reflection is in between the center of the pupil and the pupillary border 2mm Light reflection is at the pupillary border 3mm Light reflection is in between pupillary border and limbus 4mm Light reflection is at the limbus
KIMPSKY TEST
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Vaugn Asbury’s General Ophthalmology 39 Edition
SIMPLE TEST OF BINOCULAR ALIGNMENT/ HIRSCHBERG METHOD Procedure:
1. Have the patient look toward a penlight held several feet away. (33 cms according to Vaughan & Asbury’s 18th ed. Page 244) 2. Note for the pinpoint light reflection, or “reflex,”. Note: In normal eyes, pinpoint light reflec tion, or “reflex,” should appear on each cornea and should be centered over each pupil if the two eyes a re straight in their alignment. If the eye positions are convergent, such that one eye points inward (“esotropia”), the light reflex will appear tem poral to the pupil in that eye. If the eyes are divergent, such that one eye points outward (“exotropia”), the light reflex will be located more nasally in that eye. th
Vaugn Asbury’s General Ophthalmology 39 Edition
The Krimsky test is essentially the Hirschberg test, but with prisms employed to quantitate deviation of ocular misalignment by determining how much prism is required to centre the reflex [2] The Krimsky test is advisably used for patients with tropias, but not with phorias. https://en.wikipedia.org/wiki/Hirschberg_test
COVER TEST - More accurate method of verifying normal ocular alignment.The test requires good vision in b oth eyes. Procedure: 1. Ask the patient to gaze at a distant target with both eyes open. If both eyes are fixating together on the
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target, covering one eye should not affect the position or continued fixation of the other eye. 2. Suddenly covers one eye and carefully watches to see that the second eye does not move (indicating that it was fixating on the same target already). If the second eye was not identically aligned but was instead turned abnormally inward or outward, it could not have been simultaneously fixating on the target. Thus, it will have to quickly move to find the target once the previously fixating eye is covered. Fixation of each eye is tested in turn.
BRUCKNER TEST
Note! An abnormal cover test is expected in patients with diplopia. However, diplopia is not always present in many patients with long-standing ocular misalignment. When the test is abnormal, prism lenses of different power can be used to neutralize the refixation movement of the misaligned eye (prism cover test). In this way, the amount of eye deviation can be quantified based on the amount of prism power needed.
The Brückner test is a qualitative assessment of ocular alignment. This test is done under dark room illumination and the direct ophthalmoscope aperture set on the largest aperture setting so as to equally illuminate both eyes. The examiner is viewing at about 1 meter away and observing the relative brightness of the fundus reflex from each eye. A whiter and brighter reflex is noted in the eye that is strabismic. To confirm a difference in color, retest monocularly to note any changes to the reflex. The strabismic eye will appear whiter and brighter as a result of the fundus reflection emanating from outside of the pigmented macula region. http://apps.ketchum.edu/ceonline/courseview.a...
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VISUAL FIELDS EXAMINATION (CONFRONTATION TEST) Seat the patient and make sure the eye not being testes is occluded Seat facing the patient at a distance of about 1m. close your eye that is directly opposite the patient’s occluded eye Ask the patient to fixate on your nose or on your open eye Hold your hands stationary midway between yourself and the patient is opposite quadrants about 30 degrees from central fixation Quickly extend then retract a finger or fingers on one hand in one quadrant of the monocular field asking the patient to state the number of fingers seen Repeat all four quadrants, testing at least twice per
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quadrant Diagram the confrontation field if an abnormality is detected Make sure to test each eye separately. When occluding the other eye, don’t d epress the eyeball because it may cause blurring of vision. During the 8part eye exam, we are expected to use only the manual test. Automated perimetry is done in sophisticated diagnostic centers. Is uses a machine that accurately records the visual fields. The machine can also determine how much light the patient can see by altering the intensity of the light being shown to the visual fields. It is advisable to make a diagram as to which visual field is blinded because it can guide you in diagnosis
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If the patient has bitemporal hemianopia (number 2) what possible disease can lead to such problem knowing that the optic chiasm is the structure affected? Pituitary tumors. In automated perimetry:
TONOMETRY Enumerate and differentiate the methods of measuring intraocular pressure globe can be thought of as an enclosed compartment through which there is a constant circulation of aqueous humor this fluid maintains the shape and a relatively uniform pressure within the globe tonometry is the method of measuring intraocular pressure using calibrated instruments. normal range is 10 to 21 mm Hg less corneal indentation is produced as intraocular pressure rises. since both methods employ devices that touch the patient’s cornea, they require topical anesthetic and disinfection of the instrument tip prior to use. with any method of tonometry, care must be taken to avoid pressing on the globe and artificially increasing its pressure.
APPLANATION TONOMETRY - intraocular pressure is determined by the force required to flatten the cornea by a standard amount. The force required increases with intraocular pressures. - the GOLDMANN APPLANATION TONOMETER is attached to the slitlamp and measures the amount of force required to flatten the corneal apex by a standard amount. - the higher the intraocular pressure, the greater the force required. - Goldmann applanation tonometer is a more accurate method than Schiotz tonometry - following topical anesthesia and instillation of fluorescein, the patient is positioned at the slitlamp and the tonometer is swung into place. To visualize the fluorescein, the cobalt blue filter is used with the brightest illumination setting. After grossly aligning the tonometer in front of the cornea, the examiner looks through the slitlamp ocular just as the tip contacts the cornea. A manually controlled counterbalanced spring varies the force applied by the tonometer tip.Upon contact, the tonometer tip flattens the central cornea and produces a thin circular outline of fluorescein. A prism in the tip visually splits this circle into two semicircles that appear green while viewed through the slitlamp oculars. The tonometer force is adjusted manually until the two semicircles just overlap, as shown in Figure 2 –10. This visual end point indicates that the cornea has been flattened by the set standard amount. The amount of force required to do this is translated by the scale into a pressure reading in millimeters of mercury.
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It can be used in any clinic or emergency room setting, at the hospital bedside, or in the operating room, but it requires greater expertise and has generally been superseded by applanation tonometers.
NONCONTACT TONOMETRY - noncontact (“air-puff”) tonometer is not as accurate as applanation tonometers. - small puff of air is blown against the cornea. - air rebounding from the corneal surface hits a pressuresensing membrane in the instrument. - does not require anesthetic drops, since no instrument touches the eye. Thus, it can be more easily used by optometrists or technicians and is useful in screening programs. - accuracy of intraocular pressure measurement is affected by central corneal thickness. The thinner the cornea, the more easily it is indented, but the calibration of tonometers generally assumes a cornea of standard thickness. If the cornea is relatively thin, the actual intraocular pressure is higher than the measured value, and if the cornea is relatively thick, the actual intraocular pressure is lower than the measured value. Thus ultrasonic measurement of corneal thickness (pachymetry) may be helpful in assessment of intraocular pressure. The Pascal dynamic contour tonometer, a contact but non-applanating technique, measures intraocular pressure independent of corneal thickness. - other applanation tonometers are the Perkins tonometer, a portable mechanical device with a mechanism similar to the Goldmann tonometer, the Tono-Pen, a portable electronic applanation tonometer that is reasonably accurate but requires daily recalibration, and the pneumatotonometer, which is particularly useful when the cornea has an irregular surface. The Perkins tonometer and Tono-Pen are commonly used when examination at the slitlamp is not feasible, for example, in emergency rooms in cases of orbital trauma with retrobulbar hemorrhage and in operating rooms during examinations under anesthesia.
SCHIOTZ TONOMETRY - now rarely used, measures the amount of corneal indentation produced by preset weights - advantage of this method is that it is simple, requiring only a relatively inexpensive, easily portable hand-held instrument.
OPHTHALMOSCOPY 1. Position the patient about 2 feet away 2. Turn off the light to dim the room illumination 3. Set the focusing lens of the ophthalmoscope to zero 4. Check the red reflex from a distance of 2 feet 5. Approach the patient’s eye; the instrument is steadied against the patient’s face by resting the ulnar border of the hand holding the instrument against the patient’s cheek; the thumb of the free hand raises the upper lid 6. Instruct the patient to stare into the distance 7. Dial the ophthalmoscope’s focusing lenses into place to clarify the fundus image 8. Find the optic disc by following a retinal blood vessel 9. Examine the peripapillary retina 10. From the optic disc, follow the blood vessels outward to examine the four quadrants around the posterior pole 11. Check for foveal reflex THE DIRECT OPHTHALMOSCOPE This instrument consists of a single aperture through which light is projected into the subject’s eye and the examiner views the eye. It provides a magnified image (×15) and a field of view of some 6.5 –10 degrees. A set of corrective lenses c an be dialled into the aperture. These enables the focal point of the instrument to be adjusted. The rack of lenses usually contains equal numbers of positive and negative spheres which can be dialled up to take account of the patient and/or examiner’s refractive status. If examiners wish to wear their Page 7 of 11
glasses, they can do so, and effectively they will need a zero lens in the eyepiece. The patient’s refraction must also be taken into account and the relevant lens dialed into place. With highly myopic or hypermetropic patients, their glasses can be left on and used to nullify the effect of the refractive variation. Alternatively plus and minus 10 or 20 D lenses can be positioned in the sight aperture to take account of very high hypermetropia or myopia. The size and brightness of the illumination spot can be varied with the appropriate controls. Additional features vary among the different models but include a slit filter, producing a vertical slit of light which can be used to examine contours or elevations on the fundus, a grid for assessing the size of a fundus lesion, and a green filter for red-free viewing. This latter filter will make red features, such as haemorrhages, stand out due to increasing contrast between the various shades of red and orange which reflect from the fundus. Some ophthalmoscopes also include a cobalt blue filter for use with f luorescein dye. The view obtained with this instrument has a narrow angle of view and a high magnification. The more myopic the patient, the more effective the magnifying effect. This is useful for examining the optic nerve head; however the view is monocular and two-dimensional.
METHOD OF USE 1. Inform patients that you are going to look at their eye with a bright light and that you will have to get very close to their face. Instruct them to breathe normally. 2. The instrument is held to the examiner’s eye with the illumination system switched on and for steadiness and ease of use a hand can be placed on the patient’s shoulder. 3. The examiner’s right eye is used for the patient’s right eye and the examiner’s left for the patient’s left eye. If the examiner finds it difficult to close one eye, or the other, then it can be left open – with practice the brain manages to ignore the image from the non-examining eye. 4. The correct lens, as described above, is dialled into the aperture. 5. The patient is asked to fix on a distant object and is told to maintain that fixation, regardless of whether the examiner gets in the way. The examiner thus knows roughly where the patient’s macula is situated and the optic disc will be just nasal to this. 6. The examiner then points the instrument’s illumination beam into the patient’s pupil and obtains a red reflex from a distance of about half a metre and slowly moves towards the patient. At this point media opacities such as cataract can be seen as black features against the red reflex. The rheostat is used to adjust the brightness of the light for the patient’s comfort. I f required, the front of the eye, cornea, iris and lens can be examined with a +10 lens dialed into the instruments lens bank. 7. Following this part of the examination the lens dial is progressively turned towards zero to focus further back
into the patient’ s eye and eventually reach the retina. It must be stressed that the head of the ophthalmoscope must be held very close to the patient’s eye in order to gain the maximum field of view. nd
Clinical Skills for the Ophthalmic Examination: Basic Procedures, 2 Edition
*For parts of the opthalmoscope: see last page
Macula is usually at temporal side while optic disc is on the temporal side.
INDIRECT OPHTHALMOSCOPY
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Binocular Indirect Ophthalmoscopy (BIO) is a technique that provides thorough view of the retina and vitreous through a dilated pupil in order to evaluate the health of the interior of the eye and to identify structural abnormalities that may be associated with reduced visual acuity thereby aiding the diagnosis of amblyopia
light to the right is reflected off of the cornea (C), while the slit to the left is reflected off of the iris (I). As the latter slit passes through the pupil, the anterior lens (L) is faintly illuminated in cross section. The patient is seated while being examined, and the head is stabilized by an adjustable chin rest and forehead strap. th
Vaugn Asbury’s General Ophthalmology 39 Edition
optometry.osu.edu
Comparison Between Direct and Indirect Ophthalmoscopy DIRECT
INDIRECT
Magnified image Can see only small area If with cataract, cannot see One handheld apparatus
Not magnified Lets you see bigger area Ideal if with cataracts Uses a head gear and a handheld condensing lenses
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Parts of Slit lamp biomicroscopy Viewing Arm. The binocular eyepieces provide stereoscopic vision and can be adjusted to accommodate the examiner's interpupillary distance. The focusing ring can be twisted to suit the examiner's refractive error. The magnification element can be adjusted with the side dial.
SLIT-LAMP BIOMICROSCOPY Identify the different parts of the slit-lamp biomicroscope Enumerate the different uses of the slit-lamp
The slitlamp is a table-mounted binocular microscope with a special adjustable illumination source attached. A linear slit beam of incandescent light is projected onto the globe, illuminating an optical cross section of the eye. The angle of illumination can be varied along with the width, length, and intensity of the light beam. The magnification can be adjusted as well (normally 10× to 16× power). Since the slitlamp is a binocular microscope, the view is “stereoscopic,” or three dimensional.
Slitlamp photograph of a normal right eye. The curved slit of
Illumination Arm The illumination arm can be swung 180 degrees side to side on its pivoting bases allowing the examiner to direct the light beam anywhere between the nasal and temporal aspect of the eye examination.The dimension of the light beam can be varied in height and width with these levers. It can provide diffuse or focal illumination as an optical cross-section of the anterior segment.Cobalt blue, or green filters can be selected with this lever.
The Patient Positioning Frame The patient positioning frame consist of two upright metal rods to which are attached a forehead strap and a chin rest. Page 9 of 11
The chin rest height can be a djusted with the knob just below it.
The Joystick The joystick allows for focusing by shifting forward, backward, laterally or diagonally. The joystick can also be rotated to lower or elevate the light beam. The locking screw located at the base secures the slit lamp from movement when it is not in use.
Just below the slit lamp table on the left is the ON switch and provides high or low options in light intensity.
Uses of Slit lamp 1. To visualize the anterior half of the globe —the “anterior segment. 2. To study the details of the lid margins and lashes, the palpebral and bulbar conjunctival surfaces, the tear film and cornea, the iris, and the aqueous can be studied. 3. Through a dilated pupil, the crystalline lens and the anterior vitreous can be examined as well. 4. Because the slit beam of light provides an optical cross section of the eye, the precise anteroposterior location of abnormalities can be determined within each of the clear ocular structures (eg, cornea, lens, vitreous body). 5. The highest magnification setting is sufficient to show the abnormal presence of cells within the aqueous, such as red or white blood cells or pigment granules. Aqueous turbidity, called “flare,” resulting from increased protein concentration can be detected in the presence of intraocular inflammation. Normal aqueous is optically clear, without cells or flare. th
Vaugn Asbury’s General Ophthalmology 39 Edition
Other uses of slit lamp biomicroscope:- Internet source. 1. Routine observation of ocular adnexia 2. Routine investigation of posterior segment 3. Monitoring signs and symptoms of anterior segment conditions 4. Further "special eye" investigations
Definition of Terms Conjugate movement: Movement of the eyes in the same direction at the same time. Deviation: Magnitude of ocular misalignment, usually measured in prism diopters but sometimes measured in degrees. Comitant deviation : Deviation not significantly affected by which eye is fixing or direction of gaze, typically a feature of childhood (nonparetic) strabismus. Incomitant deviation : Deviation varies according to which eye is fixing and direction of gaze,
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usually a feature of recent onset extraocular muscle paresis and other types of acquired strabismus. Primary deviation: Incomitant deviation measured with the normal eye fixing). Secondary deviation : Incomitant deviation measured with the affected eye fixing.
Ductions: Monocular rotations with no consideration of the position of the othereye. Adduction: Inward rotation. Abduction: Outward rotation. Supraduction (elevation ): Upward rotation. Infraduction (depression ): Downward rotation. Fusion: Formation of one image from the two images seen simultaneously by the two eyes.Fusion has two aspects. Motor fusion : Adjustments made by the brain in innervation of extraocular muscles in order to bring both eyes into bifoveal and torsional alignment. Sensory fusion: Integration in the visual sensory areas of the brain of images seen with the two eyes into one picture.
arc equals approximately 1.7 PD. Secondary deviation: The deviation measured with the paretic eye fixing and the normal eye deviating. Torsion: Rotation of the eye about its anteroposterior axis Intorsion (incycloduction): Rotation of the 12 o’clock meridia n of the eye toward the midline of the head. Extorsion (excycloduction): Rotation of the 12 o’clock meridian of the eye away from the midline of the head. Vergences (disjunctive movements): Movement of the two eyes in opposite directions. Convergence: The eyes turn inward. Divergence: The eyes turn outward. Versions: Binocular rotations of the eyes in qualitatively the same direction.
Heterophoria (phoria): Latent deviation of the eyes held straight by binocular fusion. Esophoria: Tendency for one eye to turn inward. Exophoria: Tendency for one eye to turn outward. Hyperphoria: Tendency for one eye to deviate upward. Hypophoria: Tendency for one eye to deviate downward. (See Hypotropia.) Heterotropia (tropia): Strabismus: Manifest deviation of the eyes that cannot be controlled by binocular vision. Esotropia: Convergent manifest deviation (“crossed eyes”). Exotropia: Divergent manifest deviation (“wall eyes”). Hypertropia: Manifest deviation of one eye upward. Hypotropia: Manifest deviation of one eye upward. By convention, in the absence of specific causation to account for the lower position of one eye, vertical deviations are designated by the higher eye (eg, right hypertropia, not left hypotropia, when the right eye is higher). Incyclotropia: Manifest rotation of the 12 o’clock meridian of one eye about its anteroposterior axis toward the midline of the head. Excyclotropia: Manifest rotation of the 12 o’clock meridian of one eye about its anteroposterior axis away from the midline of the head. Orthophoria: The absence of any tendency of either eye to deviate when fusion is suspended. This state is rarely seen clinically. A small phoria is normal. Prism diopter (PD): The unit of angular measurement used to characterize ocular deviations. A 1 diopter prism deflects a ray of light toward the base of the prism by 1 cm at 1 m. One degree of Page 11 of 11
