“Exam” Module Objectives This module will introduce basic exam techniques for CMV retinitis in the resource poor setting. This will assume that much of the standard equipment in an ophthalmology clinic will not be available. This will not be a comprehensive discussion on physical diagnosis in ophthalmology. Part I will discuss testing vision, visual fields, and estimating if intraocular pressure is extremely abnormal Part II will describe use of the indirect ophthalmoscope Part III will describe how to practice indirect opthalmoscopy

Testing vision Testing visual field Estimating eye pressure Exam Techniques: I Testing vision Testing visual field Estimating eye pressure

Ocular History in contrast to Internal Medicine, in Ophthalmology, history is often brief and less important than physical examination

Just a Word About Symptoms The front of the eye is richly innervated with pain fibers. The common symptoms from the front of the eye are pain, redness, itching, and discharge. ***These have no relevance to infection in the retina*** Symptoms of disease in the retina include scotoma, flashes and floaters. If one eye has normal vision the brain will favor the good eye and the patient may not notice. ***Retinal symptoms are often ignored***

Key Point Scotoma, flashes and floaters help you to localize the disease process to the retina, but do not aid in distinguishing between the different diseases.

Physical Exam Overview Measure visual acuity Visual fields estimate intraocular pressure Dilate the pupils and examine the fundus with indirect ophthalmoscopy.

Visual acuity: basic principle A measurement of visual acuity has two parts: Test distance Test object (size) For example: “the patient can see an elephant at 3 meters” gives a measurement of visual acuity

Visual Acuity: standard Snellen eye chart In the Snellen fraction 20/20, the top number represents the test distance, 20 feet. The bottom number represents the size of the test object. The larger numbers represents the increasing size of an object that a person with normal vision can see at an increasingly great distance.

visual acuity, low vision, blindness Eye care specialists measure sight against a standard known as '20/20' vision. This based on what most people are able to see on a standard eye-test chart at a distance of 20 feet (in metres this is called 6/6 vision). If you can read the chart at 20 feet you have 20/20 or 'normal' vision. “low vision” means that the sight is reduced, but not to the level that is defined as “blindness” For example, “mild low vision” might be if someone looking at a standard eye chart from 6 feet away will see what somebody with 'normal' or 20/20 vision sees from 18 feet away; “severe low vision” means that a person standing 3 feet from the eye chart will see the equivalent of what a person with 'normal' vision will see 60 feet away if someone's sight is any worse than this, they are classified as blind.

For example: The 20/200 line – the “big E” on the eye chart The top number “20” is the test distance (measured in feet) The bottom number “200” means that the test object is a size that a person with normal vision can see at 200 feet.

Again, visual acuity… if a person sees 20/40: at 20 feet from the chart that person can read letters that a person with normal vision could read from 40 feet away. In the Metric System 20/20 = 6/6, this is because 20 feet = about 6 meters.

“Blindness” The WHO definition of blindness is vision less than 20/400 (3/60) in the better seeing eye. By lucky coincidence, the “400” test object is approximately the size of the fingers on your hand. Thus, you can, anytime and easily, test if a patient is “Blind” by WHO criteria, by testing if they can count your fingers at 10 feet (or 3 meters)

Measuring Severity of Blindness Count Fingers (CF) – By WHO definition legal blindness (less than 20/400 or 3/60) is the inability to count fingers at 10 feet (3 meters). You can specify the vision further, by seeing how far away the person can count fingers (example CF at 2 feet) Hand motion (HM) - Holding the hand approximately 6-8 inches (15-20 cm) move the hand up and down and side to side. Ask the patient to tell you which way your hand is moving. Light Perception (LP) - can they perceive a light shined directly into the eye.

Pinhole The pinhole allows one to differentiate reduced visual acuity from disease versus refractive error. It allows in only the light that does not have to be focused (bent) by the refracting mechanism of the eye (cornea and lens).

With a pinhole, the only light rays that enter the eye will be the ones that do not need To be “bent” or “refracted” by the cornea and lens. Thus, “pinhole” is a quick and Simple way to determine what the retina can “see” by excluding reduced vision from Refractive causes This central ray is the only one that enters the eye with a pinhole

Visual Fields by Confrontation Have the patient fixate on your nose, while covering one eye at a time. Ask them to tell you how many fingers you are holding up. Hold up 1-3 fingers; testing all four quadrants comparing your peripheral vision to the patients. This test tells you if there are gross defects in the peripheral vision.

Central Visual Field The Amsler grid is a simple screening test used to assess the macula (central vision). Have the patient fixate on the small dot in the center, while covering one eye at a time. While fixating on the dot, the patient reports missing areas of the grid “holes” in the vision, or scotoma Face and retinal example

Central Visual Field testing at the bedside A substitute for the Amsler grid would be to use your own face as the test grid. Face the patient with 30-35 cm (12-14 inches) between you. Have the patient fixate on your nose, while covering one eye at a time. While fixating on your nose, ask the patient to report any missing areas on the face. This test is only useful if positive, a significant scotoma (up to 5°) can be missed by the patient.

Testing central vision at the bedside

Intraocular Pressure (IOP) Ophthalmologists spend a great deal of time measuring IOP, because high IOP is characteristic of glaucoma, a common disease in the eye clinic. For glaucoma the measurments must be highly precise. Glaucoma is not a concern in the AIDS clinic! In the HIV/AIDS clinic, it is important to recognize when the IOP is dramatically low, because this may be a result of retinal detachment caused by CMV retinitis

Shiotz tonometer and Goldman Applanation tonometer, Ophthalmology instruments for measuring IOP for glaucoma .

Estimating eye pressure (IOP) by palpating the eyeball, gently pressing back and forth with the tips of your two index fingers, comparing one eye to the other

Summary The exam of the eye for CMV at the primary care level always includes documenting visual acuity at least at some approximate level. Visual fields and intraocular pressure may also be simply evaluated at the bedside.