Basic Eye Exam
Additional Notes: Length 13:52
Posted April 30, 2020
If video fails to load use this link: https://vimeo.com/413729740
This is Salma Dawoud and David Ramirez from the University of Iowa. The purpose of this video is to provide an overview of basic ophthalmic examination techniques for medical students, interns and early ophthalmology residents.
While this video is not all-encompassing, our hope is that it will provide an efficient foundation upon which to develop a comprehensive exam.
In this video, we're going to cover visual acuity, pupillary exam, intraocular pressure, extraocular motility, confrontation visual fields, the external exam, and the slit lamp and funduscopic exams.
Check vision using either a near card or the distance chart. Make sure the patient is wearing their appropriate correction. The convention is to always check the right eye and then the left eye. To be more efficient, ask the patient to start by reading the smallest line possible. If they are unable, start at the largest line and work your way down. You may need to provide encouragement.
If the patient is unable to read the 20/20 line, check the vision again using the pinhole. If the vision improves, this would indicate the possible presence of refractive error.
You may need to hold up a loose lens, such as a +2.00 D lens, for checking near vision if a patient is presbyopic and does not have their reading correction. Use a near card held at a comfortable distance and check each eye as you did with distance vision.
If an occluder is unavailable (for example, in the inpatient setting), you can always substitute a piece of tissue paper.
Next is the pupil exam. First, perform a general exam of the pupils in ambient light and look for any asymmetry in size or shape. Make sure the patient is fixating at a distance target to minimize accommodation.
Assess whether the pupils react equally to bright light by shining a bright light on both eyes. This may be easier to see in lighter irides. Next, determine if the pupils dilate symmetrically when the light is turned off. Have one hand on the light switch and have the other hand shine a light from below to illuminate both pupils enough to see them when the light is turned off. Bright light emphasizes sphincter problems, and dim light emphasizes dilator problems.
Next, check the near pupil response with sustained focus on a near target for 10-15 seconds.
Then, perform the swinging flashlight test to check for a relative afferent pupillary defect, or RAPD. In dim clinic light, with the patient fixating at distance, shine the light into the right eye, observing the amplitude of the contraction phase. After 1-2 seconds, the pupils will start to "give way" and dilate; this cues you to quickly swing the light over the bridge of the nose to the left eye. The normal response of the left eye is to constrict. An RAPD would be less contraction compared to the other eye or, with a large amount of damage, relative dilation. Continue to swing the light back and forth over the bridge of the nose a number of times to mentally "average" the asymmetry of contraction, if it exists. Finally, beware of hippus, which is normal, less than 1 mm, fluctuation in pupillary size in young people.
Next, we'll check intraocular pressure with a tonopen. Instill a drop of proparacaine into the patient's eye by gently everting the lower lid and placing the drop into the inferior fornix. Always stabilize your hand on the patient's face. Next, with the tonopen, restabilize your hand and tap the tonopen lightly on the center of the cornea. The tonopen should be completely perpendicular to the cornea. If you have difficulty getting a reading, adjust the angle you're tapping on the eye. Should you need to hold the patient's lids open, avoid placing pressure of the globe and pull the upper eyelid against the superior orbital rim.
For more details on the various methods used to check intraocular pressure, see the Iowa Glaucoma Curriculum at the link displayed.
Check extraocular motility by having the patient fixate on your finger and follow without moving their head. Be systematic; a common method is to move your finger in an "H" shape. Look for any difference between the two eyes in the 6 cardinal directions of gaze. As you can see on your screen, for each direction of gaze shown, the primary muscles responsible are highlighted. Be sure to check the extremes of eye movement. A common mistake for beginners is not having the patient look far enough in any given direction.
If you are concerned for misalignment, you can further investigate using cover testing. A link to the Eyerounds video on the basics of this testing is shown on your screen.
Check confrontation visual fields by having the patient first cover their left eye. Ensure the patient is not peeking by having them use the palm of their hand. If the patient is wearing glasses, you can also use tissue paper to occlude each eye. This works especially well for inpatients. Start by checking for central deficits by asking whether any parts of your face are missing or distorted. Then check for peripheral deficits. Cover your own right eye and with your hand equidistant to you and the patient, test their ability to count fingers in all 4 quadrants. Compare their visual fields to your own. Then, test the left eye.
The external exam is helpful to look at lid and brow position, symmetry, proptosis and gross abnormalities of the conjunctiva and sclera. It can also provide information for what you might focus on at the slit lamp (for example, lid/lash position, lid lesions, etc.).
Now we move onto the slit lamp. Start by turning it on and twisting the knob on the right-hand side to unlock the base. Make sure you are positioned correctly and are not over-extended in your neck; neck and spine problems are common in ophthalmologists. Ensure the patient is positioned such that the lateral canthus is aligned with the marker on the side of the chin rest, with their forehead against the bar.
Perform gross movements by moving the base of the joystick with the bottom of your hand. Perform fine movements by moving the top of the joystick with your thumb and forefinger. Rotate the joystick clockwise to raise the beam. Rotate counterclockwise to lower the beam. Good technique is to have one hand move the illuminating arm and one hand moving the joystick. Turn the dial on the illuminating arm to adjust the width of the light beam. Adjust the vertical height of the beam by using the dial at the very top. Turn on cobalt blue light by twisting the same dial as far counterclockwise as you can until it clicks. It is a good idea to check all these functions before bringing a patient into the room for the first time.
Be methodical with your exam. Start with the lids and lashes, then the conjunctiva and sclera, then cornea, anterior chamber, iris, pupil, lens, vitreous, and finally the retina.
To start, look at the lids and lashes by panning across the lower lid. Scroll up and pan across the upper lid. Describe the size, shape, location, and character of any lesions. You can use the knob at the top of the slit beam to measure.
Next, look at the conjunctiva and sclera. Have the patient look left, right, down and up while distracting the lids and looking at the bulbar conjunctiva and fornices. Look for inflammation, masses, foreign objects, or any other abnormalities.
Pan over the cornea with a bright, wide beam and examine the epithelium for any defects. Then use a narrow, oblique beam at higher magnification to see deeper layers.
Next, examine the anterior chamber. This is best done with the room lights off and the light at maximum intensity. Focus the beam of light on the iris, then focus on the cornea. The anterior chamber is the space between these two positions. Make the beam as small as possible (by convention, 1mm x 1mm), increase magnification, and look for cell and flare.
Look at the iris next, examining for any abnormalities in shape or structure.
To look at the lens, move the light onto the pupil and focus on the blue/yellow/sometimes brown structure behind. This is a young eye so this is an example of a clear lens. Next, examine the lens using retroillumination by adjusting the illuminating arm. This can help emphasize lenticular opacities.
Push forward just past the lens and you'll see the strand-like material of the vitreous.
If concerned about a foreign body, try to flip the patient's eyelids. To do this, grab a cotton swab in your hand. Grasp as many of the upper lashes as you can, pull toward you and put the wooden tip of the cotton swab in the groove of the upper lid. At the same time, apply downward pressure while pulling the eyelashes up. If the eyelid won't stay everted, you can try to pin the eyelashes to the superior orbital rim.
To instill fluorescein, take a strip from the packaging. Drop a single drop of saline onto the strip and touch the strip to the inferior palpebral conjunctiva. Use caution to not touch the globe as this can cause false staining patterns. If you find there is too much fluorescein, you may dab the strip on a tissue paper prior to instilling into the eye. Use cobalt blue light to examine for any epithelial irregularities.
Other more advanced techniques, such as gonioscopy, can be found at the link shown.
At the slit lamp, start at low magnification with low to moderate light intensity. Straighten the slit beam and have the patient look slightly nasal. Take your lens in between your thumb and forefinger, and place your middle/ring/pinky fingers on the forehead strap over the brow. With your hands in position, look through the viewer, and focus the light on the eye. Rotate the lens directly in front of your beam and pull back as far as you can until you start to see the redness of the fundus come into focus. Maintain hand position to keep the red reflex in view. Continue to pull back with fine movements until the image is clear. Ensure you have a binocular view by alternating closing each eye. Adjust the lens right and left, up and down until you have a clear view. If there is significant glare, you can either make your slit beam shorter, or tilt the lens toward or away from you.
Once in focus, scan by moving the slit lamp. Do not move the lens. Be systematic. Find the optic nerve and pull back slightly to see the vitreous. Scan the vessels and periphery, and finally the macula and fovea.
Remember, everything is upside down and backwards. In other words, when you move the light beam superiorly, you visualize the inferior retina. Training your brain to remember this just takes practice.
Next is the indirect exam. Although difficult at first, this technique can be mastered with consistent practice.
Fit the headset snugly against your head by adjusting the various knobs. Turn the light to moderate brightness and shine it on your outstretched thumb. Hold your thumb at the same distance you'll be examining the patient's eye, which is typically just under arm's length. Adjust the eye pieces to ensure binocularity. The patient may be reclined or seated. In this video, we will examine the seated patient.
Start with the right eye. Find the red reflex with the headlight. Then, take the lens between your thumb and forefinger. Balance your middle, ring and pinky fingers on the superior orbital rim and swing the lens in front of your field. Your light beam, the lens, and the retina MUST all be in a single plane. Common mistakes include drifting of the lens and moving the head such that the light is displaced onto the cheek or forehead.
Some ways to troubleshoot if you are not seeing a focused image include moving the lens towards you and away from you. You can try very fine movements superiorly and inferiorly and left and right. If having problems with glare, try rotating the lens toward or away from you. You can also try tilting your head to the side as this can allow the two beams of light from your headlamp to enter the eye without reflecting off the iris. Examine each clock hour.
The image you see is upside down and backwards. To orient yourself, think about the pupil as a window; when you ask the patient to look up, the window displays the superior part of the retina
This concludes the basic ophthalmic exam.