Special Senses—Eyes Chapter 11

Each eyeball contains three distinct tunics (layers): 11 SPECIAL SENSES—EYES Each eye is globe-shaped and located within a hollow bony socked (orbit) in the anterior cranium. Each eyeball contains three distinct tunics (layers): Outermost layer, the fibrous tunic. Sclera cornea conjunctiva. 2

Supporting structures Eyelid and lacrimal glands. Eyelids and eyelashes Lacrimal gland Lacrimal ducts Nasolacrimal duct Drains tears from lacrimal sac to the nasal cavity. 3

Supporting structures of the eye Eyelids and eyelashes protect eyes and prevent foreign substances from entering. Lacrimal glands continuously secrete tears that travel through lacrimal ducts. Nasolacrimal duct drains tears from lacrimal sac to the nasal cavity. 4

ocul/o, ophthalm/o: eye blephar/o: eyelid opt/o: eye, vision Combining Forms – p. 508-509 ocul/o, ophthalm/o: eye blephar/o: eyelid opt/o: eye, vision retin/o: retina

Combining Forms choroid/o: choroid irid/o: iris corne/o: cornea

dacry/o, lacrim/o: tear dipl/o: double kerat/o: hard tissue Combining Forms dacry/o, lacrim/o: tear dipl/o: double kerat/o: hard tissue cor/o, core/o, pupill/o: pupil

Suffixes -opia, -opsia: vision -ptosis: prolapse, drooping -tomy: incision -tropia: turning

Build Medical Words pertaining to within the eye: /o/ /ar 10

Build Medical Words pertaining to within the eye: intra/ocul/ar

Build Medical Words prolapse of the eyelid: disease of the retina: inflammation of the conjunctiva: Pedagogical Note: Have students place a slash between each word element to identify the word parts and combining vowels. 12

Build Medical Words prolapse of the eyelid: blephar/o/ptosis disease of the retina: retin/o/pathy inflammation of the conjunctiva: conjunctiv/itis

Pathology of the Eye

Cataract Opacity or clouding of the lens or its surrounding membrane. Unilateral or bilateral. Slow development affecting visual acuity. Especially common in older persons. Cataract as shown in left eye.

Treatment Cataract Depends on degree of visual impairment. Depends on age, general health, and occupation of the individual. Glasses for mild cases. Surgery when vision is impaired. Surgical extraction of defective lens. 16

Strabismus Signs and Symptoms Visual defect in which both eyes cannot be directed to focus simultaneously on the same object. Defect may affect one or both eyes. There are two types: esotropia and exotropia. With either form, the main symptom is diplopia. 17

Signs and Symptoms Strabismus Esotropia (continued) Esotropia Eye turns inward; also called cross-eye. Type of strabismus - Esotropia 18

Signs and Symptoms Strabismus Exotropia (continued) Exotropia Eye turns outward; also called wall-eye. Pedagogical Note: You may add other disorders to this presentation and insert illustrations from the Image Bank. Just visit Medical Terminology Simplified online resource center at DavisPlus or other resources for appropriate illustrations and information. Type of strabismus - Exotropia 19

Glaucoma

Glaucoma Signs and Symptoms Accumulated fluid pressure within the eye damages the retina and optic nerve, often causing blindness. Common forms develop asymptomatically. Eye showing normal flow of aqueous humor (yellow arrows) and abnormal flow (red arrows). 21

Glaucoma Signs and Symptoms (continued) Often not detected until irreparable damage occurs to retinas or optic nerves. When symptoms appear late, they may include aching eyes and visual disturbances such as seeing halos around lights or a noticeable loss of peripheral vision. Glaucoma. Destruction of optic nerve (black arrows). 22

Macular Degeneration Signs and Symptoms Macula, small area of retina responsible for central and color vision as shown in the eye. Macula and retina 23

Stye Signs and symptoms Inflammatory infection of sebaceous glands of the eyelid. Pain, swelling, redness, and formation of pus at the site. Hordoleum (stye) 24

Vocabulary Challenge Exercise achromatopsia: congenital deficiency in color perception; also called color blindness astigmatism: defective curvature of the cornea and lens resulting in a distorted image 25

Vocabulary Challenge Exercise Conjunctivitis diabetic retinopathy 26

Vocabulary Word Challenge conjunctivitis: inflammation of the conjunctiva that can be caused by bacteria, allergy, irritation, or a foreign body; also called pinkeye diabetic retinopathy: occurs in people with diabetes, manifested by small hemorrhages, edema, and formation of new vessels leading to scarring and eventual loss of vision

11 SPECIAL SENSES—EYES Vocabulary Challenge Exercise photophobia: retinal detachment: 28

Vocabulary Word Challenge photophobia: unusual intolerance and sensitivity to light retinal detachment: separation of the retina from the choroid, which disrupts vision and results in blindness if not repaired

Diagnostic Procedures Visual acuity test Visual acuity is measured with use of a Snellen chart. Imprinted with alphabetical letters graduating in size from the smallest (bottom) to the largest (top) Patient is positioned 20 feet from the chart. Snellen chart 30 30

Diagnostic Procedures Visual acuity test (continued) Examiner has the patient cover one eye with a 3 x 5 card or eye cover. Patient then reads out loud an indicated line of letters. Lowest line on the chart that the patient is able to read accurately is used to indicate visual acuity for that eye. Each eye is tested individually. Snellen chart 31 31

Diagnostic Procedures Visual acuity test (continued) Normal vision is 20/20, which means the patient can read at 20 feet what the normal eye can read at 20 feet. Visual impairment occurs at 20/70. Legal blindness occurs at 20/200 or more with correction. 32 32

Build Medical Words inflammation of the retina: fear of light: paralysis of the eye: 33

Build Medical Words inflammation of the retina: retinitis fear of light: photophobia paralysis of the eye: ophthalmoplegia

Pharmacology Antiglaucoma drugs Reduce IOP by lowering amount of aqueous humor in the eyelid, reducing its production, or increasing the outflow. Miotics Cause pupils to constrict. Increase outflow of eye fluids. 35

Mydriatics Pharmacology Cause pupils to dilate. Used to prepare eyes for internal examination. 36