Exam techniques II: Indirect Ophthalmoscopy PRINCIPLES Comparison of direct ophthalmoscopy vs indirect ophthalmoscopy Step by step: how to do it! Several practical observations

A Torch or a direct ophthalmoscope are not enough

Anybody can learn indirect Ophthalmoscopy It’s the same as learning how to ride a bicycle or drive a car… It just takes practice!

Direct vs Indirect ophthalmoscope

Indirect Ophthalmoscopy Direct Ophthalmoscopy “bird’s eye” view – wide field, 20-30 degrees, depending on the lens – able to scan the entire retina rapidly Very small field of view – extremely laborious to study the entire retina Binocular view – stereopsis – see in “3 D” Uniocular view - no steropsis Image upside down and backwards Image erect Better performed while the patient is lying Better performed in sitting position Better view in hazy media Very poor in hazy media Periphery of the retina can be examined even to the ora serrata Periphery of retina beyond equator is difficult to see Drawing of retinal lesions “easy” Drawings of retinal lesions very difficult Examination of the retina performed with the patient at “arms length” Examination of the retina performed with the examiners face immediately against the patient’s face Great comparison chart

Narrow field (direct) vs wide field (indirect) Direct ophthalmoscope Indirect ophthalmoscope Replace indirect with normal Optic nerve

Vortex vein Superior temporal Vascular arcade fovcea Optic nerve Posterior ciliary out Inferior temporal Vascular arcade

Superior temporal Vascular arcade fovea Optic nerve Inferior temporal Vascular arcade

Fully dilate the pupil

Remember: the area (of a circle)=Π x radius squared Remember: the area (of a circle)=Π x radius squared! If you double the pupil size with dilation, the “window” (pupil) is open four times as wide (and the view is much better)

Indirect Ophthamoscopy three moveable objects need to be coordinated Headlight hand lens eye

Headlight The first step is to put the spectacle mounted headlight on. Yellow text a little hard to read The first step is to put the spectacle mounted headlight on. Snug up the head cord so the glasses are comfortable and well seated. Next hold your thumbs together at arms length – you should be able to see your thumbs + see them illuminated by the light.

Hand Lens Hold the lens between the thumb and index finger. Rest the other three fingers on the patient’s brow or the side of the eye. Steady the lens against the patient to control the distance of the lens from the eye and to keep the distance the same in order to keep the image in focus.

Practice simply looking at the eye and directing the light at the eye. Move your head side to side and up and down, and watch the light beam. Your head movements direct the light. You may also need to move your head closer or farther away to focus the image. Eye

The Patient (owner of “the eye”) 1. The normal reaction to having a bright light shined in your eye is to shut your eye, or gaze away from the light. 2. Looking directly at the light exposes the most sensitive part of the retina. 3. The reflex to shut the eye can be controlled to some extent by instructing the patient to keep the other eye open. The eyes are “yoked” together. The direction of gaze can also be controlled this way. ***If a patient does not react to your light – immediate worry the eye is blind. (these are the best eyes to practice on)*** Exam photos of how to control direction of sight

Red Reflex Practice getting a red reflex using the light alone. You will gain an instinctive sense about what a normal “red reflex” looks like - the color and brightness. Remember if you can’t get a red reflex, there may be corneal scar, or cataract, or debri in the vitreous cavity.

Red Reflex If at any time or in any gaze direction you see an abnormal red reflex, be sure that you carefully study that area of retina. A “sickly yellow” red reflex may be from a retinal detachment, or CMV. Even a small area of abnormal retina can give an abnormal red reflex.

Alignment of the headlight, the lens, and the patient’s eye Imagine a string always held stretched and straight One end of the string is fastened to the spot on the retina that you wish to see. The string passes thru the patient’s pupil The string must always then pass thru the center of the hand lens and perpendicular to the hand lens The other end of the string is fastened to the light of the indirect ophthalmoscope Make a string teaching aide??

Focusing the image Get perfect alignment “with the string” Hold the lens very close to the eye and with your other fingers braced on the patient – the rim of the eye Slowly back the lens away from the patient keeping perfect alignment “along the string” Viola! – a beautiful image of the retina will fill the lens You can also “fine-tune” the focus by moving your head closer or further away, staying lined up

“tricks” for controlling the patient’s gaze Remember that the eyes are “yoked” together – remind the patient to keep both eyes open and look in the desired direction with both eyes Give the patient a target (the patients thumb that you can move around, the patient’s ear, shoulder, feet…) Gently tap the patient’s forehead in the direction you want the patient to look

Examine the entire retina with the same system every time

Your system needs to become a “habit” Some people find it easiest to start with the posterior pole (ON and Macula) for the examiner’s orientation. Other people find it most efficient to examine the macula and optic nerve last, because that area is most sensitive and the area most likely to cause the patient to loose cooperation

There are 10 directions for the patient to gaze 9 steps if you start at 12 O’clock and repeat at 12, PLUS Straight into the light

drawing what you see

The image is upside down and backwards! (or, “rotated 180 degrees”) For most people, the most difficult part of indirect ophthalmoscopy is confusion about where things are located because of this Reminding yourself of basic landmarks helps: always start with the optic nerve, then identify the superior and inferior temporal arcades, then the fovea Drawing what you see

For next traiing – use ofrms Some people find it helpful to use paper that has a printed schematic drawing of the retina

There are two systems for drawing things in the correct location Place the retinal drawing paper upside down and backwards, and copy what you see, exactly as you see it. Then when you turn your paper the right way around, lesions will be in the correct place The second system is to “transpose” in your head – turn things back around the correct way mentally - by always reminding yourself: if the patient looks up, the lesion is superior; if the patient looks down, the lesion is inferior; if the patient looks nasal, the lesion is nasal; if the patient looks temporal, the lesion is temporal

Vortex vein Superior temporal Vascular arcade fovcea Optic nerve Posterir ciliary out Infeerior temporal Vascular arcade

Superior temporal Vascular arcade fovea Optic nerve Inferior temporal Vascular arcade

Summary The exam of the eye for CMV at the primary care level always includes documenting visual acuity at least to some approximate level. Visual fields and intraocular pressure may also be simply evaluated at the bedside. The indirect ophthalmoscope provides a “bird’s eye view” of the retina and is the single critical tool for the diagnosis of CMV retinitis

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