Transcript Eyes
Eyes By Orest Kornetsky Eye Anatomy – Why Study It? Why should you care? Optometrist – Doctor of optometry, 4 year undergrad + 4 year optometry school Ophthalmologists – Medical doctors In general, optometrists practice primary and preventive eye care, while ophthalmologists perform eye surgery What do nurses do? History Vision difficulty? Eye pain? Photophobia – inability to tolerate light Childhood strabismus? Halos around lights – in glaucoma Scotoma – blind spot in visual field – in glaucoma, optic nerve, and visual pathway disorder Night blindness – Vit A deficiency, glaucoma, A history of crossed eyes? AKA “lazy eye” Redness or swelling? Infections? History cont. Excessive or lack of tearing? May be due to irritants or obstruction in drainage Past history of ocular problems? Glaucoma? Family history? Use of glasses or contact lenses? When tested last? Any medications? Anatomy of Eyelid Eyelids (L. palpebrae) protect the cornea and eyeball from injury Canthi (sing. canthus) are corners of the eye, also called angles of eye Caruncle is located near medial canthus and contains sebaceous glands Tarsal plates are made of connective tissue and strengthen eyelid. They contain meibomian (tarsal) glands which secrete lipid to create airtight seal when closed and also prevent eyelids from sticking together Inspecting External Ocular Structures General Eyebrows Note if facial expression is relax or tense Note if movement is symmetrical Eyelids and lashes Note if any redness, swelling, discharge or lesions Note if eyelid closes completely and if drooping Pallor of lower lid is good indicator of anemia For upper eyelid, use applicator stick to fold the eyelid over (Fig 14-17) Abnormalities in Eyelids Ectropion Lower lid rolls out, causing an increase in tearing The eyes feel dry and itchy due to inappropriate itching Increase risk for inflammation Occurs mostly in elderly due to atrophy of elastic tissue Entropion The lower lid rolls in Foreign body sensation Abnormalities in Eyelids Periorbital edema May occur with local infection of systemic condition (CHF) Ptosis Occurs with neuromuscular weakness (myasthenia gravis) or CN III damage Lesions on the Eyelids Blepharitis Chalazion Inflammation of eyelids Staph or dermatitis Burning, itching, tearing, foreign body sensation, pain A cyst in or an infection of meibomian gland Nontender, firm, overlying skin freely movable Hordeolum (Stye) Localized Staph infection of hair follicle at lid margin Painful, red, swollen, purulent Anatomy of the Eye Lacrimal apparatus provides irrigation of conjunctiva glands – secrete lacrimal fluid (tears) Lacrimal ducts – lacrimal fluid to conjunctiva Lacrimal canaliculi (puncti) – drain fluid into Nasolacrimal duct – conveys lacrimal fluid to nasal cavity Lacrimal Inspecting the Lacrimal Apparatus Inspect for bulges or pressure near canaliculi Dacryocystitis Inflammation of the lacrimal sac and/or nasolacrimal duct Dacryoadenitis Infection of lacrimal gland Dacryoadenitis Dacryocystitis Anatomy of Extraocular Muscles 4 rectus (straight) 2 oblique Innervations SO4 – Superior oblique m. LR6 – Lateral rectus m. CN IV (trochlear n.) CN VI (abducens n.) AO3 – All other muscles CN III ( Trigeminal n.) Extraocular muscle movement Extraocular Muscle Dysfunction Anatomy of the Eyeball – Outer Layer Sclera – tough protective white covering (posterior 5/6) Cornea – transparent part of the fibrous coat covering the anterior of the eyeball (anterior 1/5) Conjunctiva – transparent protective covering of exposed part of eye (palpebral conjunctiva covers inside of eyelash) iris Corneal reflex – lightly touching the eye with cotton stimulates a blink. Trigeminal n. (afferent) Facial n. (efferent) Inspection Conjunctiva Sliding the lower lids down, observe for redness on conjunctiva and if eyeball looks moist and glossy Reddening may be pathogenic Sclera Should be white, although may have gray-blue hue Might contain yellowish fatty deposits beneath the lids Yellowing of sclera indicates jaundice Vascular Disorders of Eye Conjunctivitis “Pink eye” Due to bacterial, viral, allergic, or chemical irritation Redness throughout the conjunctiva, but usually clear around the iris Purulent discharge usually common Symptoms: itching, burning, foreign body sensation Iritis Red halo around the iris and cornea Pupils may be irregular due to swelling Symptoms: photophobia, blurred vision, throbbing pain Inspecting Cornea and Lens Corneal abrasion Assess by shining a light and observing from the side Pupillary light reflex Charted according to size of pupil Charted as a ratio of before light/after light (3/1) A sluggish response may be caused by increased ICP No response may indicate neurological damage How to chart pupillary light reflex? PERRLA: Pupils Equal, Round, React to Light and Accommodation Anatomy of the Eyeball – Middle Layer Canal of Schlemm Choroid – provides vascularity to retina Pupil – variable-sized, black circular or slit shaped opening in the center of the iris that regulates the amount of light that enters the eye. Appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. Lens – biconvex disc controlled by the ciliary muscle to produce far vision when flat Anterior chamber Aqueous humor is produced by the ciliary body and secreted into posterior chamber of eye. From there, aqueous humor travels to the anterior chamber where it exits through the Canal of Schlemm Determines intraocular pressure Increase leads to Glaucoma Vascular Disorders of Eye Physiology review: Aqueous humor is produced by the ciliary body and secreted into posterior chamber of eye. From there, aqueous humor travels to the anterior chamber where it exits through the Canal of Schlemm Glaucoma Excessive pressure in eye due to blockage of outflow from anterior chamber This puts pressure on optic nerve Redness around the iris, dilated pupils Symptoms: sudden clouding of vision, sudden eye pain, and halos around lights Disorders of Opacity of Lens Cataract Anatomy of the Eyeball – Inner Layer Retina – visually receptive layer where light waves are changed to nerve impulses Optic disc – area where the optic nerve enters the eyeball Fovea centralis – area of most acute vision Inspecting the Ocular Fundus Using an ophthalmoscope to inspect the internal surface of the retina, anterior chamber, lens, and vitreous. Darken the room to dilate the pupils Remove eye glasses, contacts may stay in Ask person to stare at distant object Hold ophthalmoscope close to your eye and move to within a few inches of the person’s face A red glow filling the pupil is called the red reflex and is caused by light reflecting off the retina Cataracts appear as opaque black areas against the red reflex Inspecting the Optic Disc and Retina Normal optic disc is: Yellow-orange to pink Round or oval Distinct margins Normal retina is: Arteries in each quadrant Arteries are bright red Visual pathways Testing Visual Reflexes Pupillary light reflex Constriction of pupils when bright light shines on the retina Direct light reflex – constriction of same sided pupil Consensual light reflex – simultaneous constriction of both pupils The impulse is carried afferently by CN II and efferently by CN III Accommodation Adaptation of eye for near vision Ask person to focus on distant object (dilates the pupils). Then ask person to shift gaze to near object few inches away. A normal response is pupillary constriction and convergence of axes of the eyes Testing Visual Accuity Snellen Eye Chart Standing 20 feet from the chart Test one eye at a time by covering the other eye Leave contact lenses and glasses on, unless the glasses are reading glasses Normal vision is 20/20 Near vision Use Jaeger card (smaller version of Snellen chart) or just read newspaper Testing Visual Fields Confrontation test Measures peripheral vision compared to examiner (assuming examiner’s vision is normal) Both examiner and pt cover one eye with a card, stand about 2 feet away, and maintain eye contact Advance finger, starting from periphery, and ask patient to say “now” when the finger is first visible Inability to see when the examiner sees suggests peripheral field loss Testing Ocular Muscle Function Cover Test Detects deviated alignment of eyes Ask pt. to stare straight at your nose and cover one of the pt.’s eyes with a card While noting the uncovered eye, move away the card A normal response is a steady fixed gaze Diagnostic Position Test Ask pt. to hold head straight and move finger in all positions, holding it about 12 inches away A normal response is parallel tracking of the objects with both eyes Nystagmus Fine oscillating movements around the iris Normal at extreme lateral gaze Developmental Considerations – Infants and Children Strabismus – must be detected and treated early to prevent permanent disability Esotropia – inward turning of eye Exotropia – outward turning of eye Color vision – due to inherited Xlinked recessive trait, occurs more often in boys External eye structures – an upward lateral slope together with epicanthal folds occurs in Down syndrome Ophthalmia neonatum – conjunctivitis due to bacteria, virus, or chemical irritation Developmental Considerations – Aging Decrease in visual acuity, diminished peripheral vision Ectropion (drooping of lower lid) or entropion (eyelids turning in) Pinguecula – yellow nodules due to thickening of conjunctiva as a result of prolonged exposure to sun, wind, and dust Developmental Considerations Aging Arcus senilis – graywhite arc seen around the cornea. Due to deposition of lipids. No effect on vision Xanthelasma – raised yellow plaques. Normal THE END EYE HOPE YOU HAVE A GREAT DAY!!!