Question

Lab Assignment

Part 1

What are the abnormal characteristics of lymph nodes associated with acute infection, chronic inflammation, and cancer?

What are the facial characteristics that occur with Down syndrome?

Part 2

Discuss three concentric coats of the eyeball.

Distinguish between direct light reflex and consensual light reflex.

Discuss visual changes that occur with older adults.

Part 3

Describe the functions of the middle ear.

Discuss using an otoscope for an infant vs an adult.

Identify the types of hearing loss.

Answer 1

Part 1

Abnormal characteristics of lymph nodes associated with acute infection

Acute infection—acute onset, <14 days' duration, nodes are bilateral, enlarged, warm, tender, and firm but freely movable.

Abnormal characteristics of lymph nodes associated with acute infection

Chronic inflammation (e.g., in tuberculosis the nodes are clumped).

Abnormal characteristics of lymph nodes associated with cancer

Cancerous nodes are hard, >3 cm, unilateral, nontender, matted, and fixed.

What are the facial characteristics that occur with Down syndrome?

Common physical features of Down syndrome include:

• A flattened face, especially the bridge of the nose
• Almond-shaped eyes that slant up
• A short neck
• Small ears
• A tongue that tends to stick out of the mouth
• Tiny white spots on the iris (colored part) of the eye

Part 2

Discuss three concentric coats of the eyeball.

Sclera-outer layer, clear protective, contains cornea

Choroid-middle layer, contains pupil and lens

Retina-inner layer, contains optic disk and retinal vessels

Distinguish between direct light reflex and consensual light reflex.

The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness. A greater intensity of light causes the pupil to constrict (miosis/myosis; thereby allowing less light in), whereas a lower intensity of light causes the pupil to dilate (mydriasis, expansion; thereby allowing more light in). Thus, the pupillary light reflex regulates the intensity of light entering the eye. Light shone into one eye will cause both pupils to constrict.

A consensual response is any reflex observed on one side of the body when the other side has been stimulated.

For e.g., if an individual's right eye is shielded and light shines into the left eye, constriction of the right pupil will occur, as well as the left. This is because the afferent signal sent through one optic nerve connects to the Edinger-Westphal nucleus, whose axons run to both the right and the left oculomotor nerves.

Discuss visual changes that occur with older adults.

The involutional changes here mirror similar changes occurring throughout the face and extremities. Gradual tissue atrophy as the mesodermal content of the body begins to shrink; the envelope of the ectoderm becomes too large, and redundant skin folds and wrinkles appear. Loss of adnexal structural support of tarsus, canthal tendons, and orbicularis muscle with thinned skin leads to orbital fat prolapse, eyelid malposition, blepharoptosis, and tearing.

In the lower eyelid, horizontal lid laxity is common. It can be determined by the pinch test, which is the amount the eyelids can be pinched away from the globe and the relative delay and the absence of snap in the lids ability to regain its normal anatomical position. Reduction in the orbital fat with ageing causes the eyes to “sink in” accentuating the lid laxity. Progressive laxity can result in punctual eversion and later eversion of the eyelid margin from the globe (ectropion) and subsequent symptoms of a watery eye. Generalised descent of all of the mid‐face because of ageing further contributes to ectropion formation. If the pretarsal orbicularis muscle is comparatively strong, the eyelid may undergo inversion (entropion) instead causing eyelashes to rub against the cornea and subsequent discomfort. Oculoplastic surgeons operate symptomatic ectropion or entropion. These conditions may also be operated upon before a cataract operation to avoid infection. In entropion, temporary relief may be achieved by simply taping the lid to pull it outwards.

In the upper lids, the disinsertion or attenuation of the levator muscle may cause involutional ptosis. Age related descent of the brow (brow ptosis) also contributes to the ptosis formation. Excess upper eyelid skin along with anterior migration of the preaponeurotic fat pads results in dermatochalasis or pseudoptosis. These are operated upon if they are interfering visually.

Watery eye in the elderly, although mainly caused by eyelid malposition, can sometimes result from true lacrimal obstruction. If the nasolacrimal duct obstruction causes distressful watering or recurrent infections it can be treated by dacryocystorhinostomy. The other end of the spectrum is reduction in the amount of tears produced by the lacrimal gland causing dry eyes. This is treated with artificial tears or punctual plugs to retain tears in the conjunctival sac.

Corneal changes

Changes in corneal toricity (curvature) cause alteration in refraction in elderly, usually a change from the “with the rule” astigmatism to “against the rule” astigmatism. In with the rule astigmatism, the vertical meridian of the cornea is steeper than the horizontal meridian and the eye has more refractive power (plus cylinder) along the vertical axis, hence the patient has difficulty resolving targets with horizontal lines, for e.g., letters like E or F. In against the rule astigmatism, the horizontal meridian is steeper than the vertical and the eye has more refractive power (plus cylinder) along the horizontal axis, hence the patient has difficulty focusing vertically oriented targets. Hence, because of presbyopic changes and astigmatism changes regular refraction check ups are advised for the elderly to help them see optimally.

Other corneal changes include decrease in corneal luster and corneal sensitivity and increase in corneal fragility.

Age related dystrophic changes occur in corneal epithelium, stroma, and endothelium. Hudson‐Stahli line is a pigmented line of iron deposition commonly seen at the junction between middle and lower third of the cornea and is thought to be depostion from the tear film over the opposing lower lid margin. Arcus senilis is the most prominent and frequent ageing change seen in the cornea. These asymptomatic bilateral yellow‐white deposits usually begin inferiorly and then superiorly to form an annular opacity on the peripheral corneal stroma separated from the limbus by a narrow band of clear cornea. The deposits are composed of cholesterol esters, cholesterol, and neutral glycerides. Hassall‐Henle bodies are localised thickenings in the periphery of the endothelium of the ageing cornea seen on specular reflection on slit lamp tesing. If these descemet membrane excrescences occur axially in the corneal endothelium they are called cornea guttata. Kruckenberg spindle is the deposition of uveal pigment on the corneal endothelium with ageing. All the above mentioned changes by themselves do not interfere in vision.

Part 3

Describe the functions of the middle ear.

Also known as the tympanic cavity, the middle ear is an air-filled, membrane-lined space located between the ear canal and the Eustachian tube, cochlea, and auditory nerve. The eardrum separates this space from the ear canal. The area is pressurized.

The eardrum acts as a natural boundary between the middle ear and the ear canal. Pressure in the middle ear is maintained through the Eustachian tubes, which are closed when not in use. Each time a person swallows, the Eustachian tubes open and allow fresh air to enter into the tympanic cavity. This maintains a constant pressure gradient. Sometimes, this pressure is not equalized with the environment outside the head, and this is often the reason why some people experience discomfort in airplanes and at higher elevations

The cavity also plays a very important role in a person’s ability to hear. Inside the middle ear, three small bones (ossicles) form a chain and conduct sound vibrations from the eardrum to the inner ear. Once in the fluid-filled inner ear, sounds are converted into nerve impulses and sent to the brain.

Discuss using an otoscope for an infant vs an adult.

Technique (Adult)

1. The patient should be sitting on the testing table
2. Position the patient's head so you can see comfortably through the instrument
3. Grasp the auricle and firmly but gently pull it upward, backward, and slightly away from the head (straightens the EAC, should be painless)
4. Turn the otoscope light on and hold the handle between your thumb, index finger, and middle finger and point the handle upward or laterally
5. Brace your hand against the patient's temple/cheek using your fourth and fifth fingers to stabilize the otoscope and guard against trauma with sudden movements
6. Direct the speculum in a slightly downward fashion as you insert it into the EAC approximately 0.25 to 0.5 inches
   1. Remove cerumen, discharge, debris, or foreign bodies if inhibiting direct visualization of the TM
7. Inspect the walls of the EAC
8. Carefully move the speculum to see as much of the TM as possible
9. Inspect the TM for color, translucency, vascularity and position
10. Identify the umbo, manubrium of the malleus, the light reflex, the pars flaccida, and the pars tensa
11. Use a pneumatic otoscope to assess the TM mobility
    1. Insert the pneumatic otoscope into the ear canal and ensure an airtight seal (failure to obtain a seal can produce a false-positive/lack of movement finding)
    2. Squeeze the bulb to introduce air into the canal (the TM and its light reflex should move inward) being careful not to apply excessive pneumatic pressure
    3. Release the bulb to remove air (TM should move outward)  

Technique (Child)

1. Have the child sit in the parents lap or lie down on their side, back, or abdomen with the ear to be tested facing upwards
   1. If lying down, have the parent hold the arms either extended or close to the sides to limit motion
   2. If sitting, place the child's legs between the parents legs and have the parent place one arm around the child's body and use the other hand to hold the child's head firmly against the parent's chest
2. Grasp the auricle with your thumb and forefinger of your nondominant hand and pull to straighten the canal
   1. The EAC curves upward in infants so pull down and back to the 6 to 9 o'clock range
   2. The EAC curves downward and forward in children >3 years of age so pull up and back toward a 10 o'clock position
3. Insert the speculum into the meatus between the 3 and 9 o'clock positions in a downward and forward position no more than 0.23-0.5 inches (in older children)
   1. In neonates and infants, the 2 mm speculum may need to be inserted deeper due to the underdeveloped cartilaginous and bony structures
4. Continue steps 4-11 listed above

Identify the types of hearing loss.

Conductive Hearing Loss

Sensorineural Hearing Loss

Mixed Hearing Loss