Terms Abrasion-scrapping injury to the skin or a membrane such as the cornea of the eye Amblyopia-reduced or dimness of vision Aqueous Humor-watery fluid that circulates thru anterior and posterior eye chambers Bony Orbit-rounded out socket in the skull or cranium where the eyeball sits Canthus-inner or outer corner where the eyelids meet
Terms Crystalline lens-part of the eye that in addition to the cornea, refracts light rays and focuses them on the retina Exophthalmia-abnormal protrusion of the eyeball from the bony orbit (related to thyroid condition or orbital tumor) Extra-ocular-outside globe of the eye Extrinsic eye muscles-muscles that connect the eyeball to the orbital cavity Glaucoma-eye disease (↑ intraocular pressure = optic nerve atrophy and blindness) Globe- eyeball Hyperopic-light rays come to focus behind the retina (farsightedness) Myopia-light rays come to focus in front of the retina (nearsightedness) Objects only seen if up close or near/can’t see farther away
Terms Intraocular-inside globe of the eye Intrinsic eye muscle- muscle located inside the eyeball (iris and ciliary body) Iris- colored eye membrane; separates anterior and posterior chambers; contracts and dilates to regulate light ray entrance Limbus- edge of cornea where it unites with the sclera Optic nerve- II cranial nerve responsible for vision Sensory receptors- rods and cones in the retinal layer (stimulated by light rays conduct nerve impulses to the optic nerve)
Abbreviations OD oculus dexter = right eye OS oculus sinister = left eye OU oculus unitas = both eyes
Purpose of Eye Surgery Preserve or Restore Vision
Fibrous Tunic 2 parts: Sclera forms posterior portion of eyeball Extrinsic eye muscles attach to this layer Cornea forms anterior 1/3 eyeball Cornea is transparent and avascular Both cornea and sclera serve to protect the retina Outer layer which covers and protects the exposed portion of the eyeball and the inner eyelid is the conjuctiva
Vascular Tunic 3 parts: Choroid Provides nutrients/large number of blood vessels Pigmented layer, thin and dark Function to absorb light, reason see black in the pupil Pierced by the optic nerve Ciliary body 2 parts: Ciliary muscle holds lens in place Changes lens shape with accommodation (near and far focusing) Iris Radial/circular smooth muscle with hole in the center (pupil) Controls size of pupil, therefore amount of light coming in and out
Nervous Tunic Innermost layer Where retina ends anteriorly called ora serratus (scalloped region Contains nerves 3 parts: Photoreceptor layer which consist of rods and cones Bipolar layer photoreceptors synapse with bipolar neurons Ganglia layer bipolar neurons feed into one ganglia neuron this is the optic disc or blind spot an area where there are NO photoreceptors
Rods and Cones Rods Found in periphery of center of back of eye Not found in center of eye Vision in dim or dark light Allows vision of shape, movement and shades of gray Overstimulation causes pain (ex. dark to bright light) Cones Packed in one tiny area called macula lutea (where vision most acute/accurate) Indention here is called the fovea centralis In the light, sharpness of vision, shapes, movement, color Each cone has one of three pigments: erythrolabe, chlorolabe, cyanolabe
Colorblindness (FYI) Erythrolabe (red pigments) Chlorolabe (green pigments) Cyanolabe (blue pigments) Depending on color coming in, determines which receptors are stimulated Colorblind means are lacking in one pigment, usually erythrolabe Total colorblindness means no pigments are present
Cavities of the Eye Anterior Cavity Posterior Cavity Separated by transparent structure called the lens whose function is to bend and focus light onto the macula lutea Cataracts form with loss of the lens’ transparency
Anterior Cavity From the lens forward Contains aqueous humor which is watery Formed in the ciliary body Provides nutrients, helps bend light Drained by canal of Schlemm where the cornea meets the sclera Too much causes increased IOP (intraoccular pressure), untreated causes glaucoma/seen in chronic unmanaged hypertensive patients
Anterior Cavity Contains 2 chambers: Anterior chamber anterior to iris Posterior chamber posterior to iris Both contain aqueous humor
Posterior Cavity From lens back/posterior to lens Contains thick gelatinous clear fluid called vitreous humor Vitreous humor keeps the eyeball from collapsing, holds the retina in place, and helps to bend light Body produces all it needs when you’re born You cannot produce anymore
Orbit May be called the bony orbit = socket that eyeball sits in Seven bones form the orbit: Frontal, sphenoid, ethmoid, superior maxillary, malar (zygomatic), lacrimal, and palate (see figure 16-1, AST pg 577)
Eye Muscles 1. Extrinsic Eye Muscles Muscles that connect the eyeball to the orbit and allow for movement of the eye Six total extrinsic muscles: Superior rectus– movement up and temporal Inferior rectus- movement down and temporal Medial rectus- straight nasal Lateral rectus- straight temporal Superior oblique- movement down and nasal Inferior oblique- movement up and nasal 2. Intrinsic Eye Muscles Muscles located inside the eyeball Includes: Iris Ciliary body
Lacrimal System Lacrimal Gland- secretes tears and keeps cornea moist Located in upper eyelid at outer angle Excretory Ducts Carries fluid to surface Empty into lacrimal sac which becomes the nasolacrimal duct leading to the nasal cavity
Nerves and Blood Supply 2 nd cranial nerve (optic nerve) vision 3 rd cranial nerve (oculomotor) 1° motor nerve medial rectus, inferior rectus, superior rectus, and inferior oblique muscles 4 th cranial nerve (trochlear) superior oblique 6 th cranial nerve (abducens) lateral rectus Formula to remember LR6(SO4)3 3 stands for the rest of the extraocular muscles Ophthalmic artery supplies orbit and globe, branches off the carotid artery Branches of ophthalmic artery supply globe, muscles, and eyelids Alexander’s p. 664
Physiology of Vision Light comes into eye Light passes thru cornea and pupil Iris regulates amount of light entering Light goes through lens (light is refracted) Light then to the retina Light rays stimulate rods and cones (sensory receptors of retina) Impulses conveyed to the optic nerve Optic nerve to the brain In the brain, the visual area of the cerebral cortex in the occipital lobe of the cerebrum interprets vision
Physiology of Accommodation (Focus) w
Cataracts Crystalline lens has become opaque Is a condition, not a disease Prevents light passage Vision is impaired gradually Can cause blindness, untreated Causes: aging, certain drugs, chemical exposure, sunlight exposure, disease, congenital
Retinal Detachment Small Develop around a retinal tear Vitreous pulling away from retina, fluid becomes stringy (see spots and flashes of light) Corrected by laser or cryotherapy Large With tear, vitreous gets under tear and under retina separating it from the choroid Vision is lost where retina detaches See veil or shadow from one side, above or below Completely detached, all vision is lost in that eye
Vitreous Hemorrhage With retinal tear, blood vessels torn and vitreous hemorrhage occurs Vitrectomy must be performed to determine if a retinal tear has occurred
(PVR) Proliferative Vitreoretinopathy Occurs 5-10% post-scleral buckle (procedure performed to repair detached retina) Scarring pulls on retina creating re- detachment
Epiretinal Membrane Scarring over the macula (area of retina where vision most accurate) results in a cloudy appearance Membrane is removed surgically
Corneal Pathology Clouding of the cornea results in diminished vision Caused by: Eye injury Corneal infection Disease Any eye surgery Corrected by corneal transplant (keratoplasty)
Chalazion Lump in the inner or outer eyelid surface Inflammatory reaction to debris trapped in oil- secreting gland of the eyelid Eyelid can become red and swollen Hot compress produces cheese-like discharge
Dacryocystitis Inflammation of the lacrimal sac Caused by obstruction of the nasolacrimal duct Area below eye beside nose is red and swollen Sensitive May have a mucous discharge at inner canthus Surgery entails opening blockage and treating infection
Strabismus Misalignment of the eyes “Cross-eyes” (esotropia) “Wall eyes” (exotropia) Due to restrictive or paralytic eye muscles Are six eye muscles Corrected by Recession and Resection
Pterygium Fibrous wedge shaped benign conjunctival growth that often extends out into the cornea Treatment usually with steroidal anti-inflammatories If extend into cornea, vision is impaired requiring surgical intervention Pterygium repair may involve removal of part of the conjunctiva
Entropian Inversion (turning in on itself) of the lower eyelid
Ectropion Eversion (turning out) of the lower eyelid
Diagnostics & Testing Visual exam Vision impairment complaints Eye pain, irritation, burning, drainage, redness Asymmetry Ophthalmoscope exam by physician History of HTN, diabetes, allergies, medications patient is on Tonometer - measures intraocular pressure
Anesthesia General (children, selected patients) Retrobulbar Block Both Local Idea to keep eye completely still and lower intraocular pressure
Medications Label immediately Most are colorless and you must label to avoid any confusion with identity Classifications: Anesthetics Antibiotics Anti-inflammatories Irrigants Miotics Mydriatics/cycloplegics Vasoconstrictors Dyes Viscoelastic agents Enzymes
Anesthetics Injectable Xylocaine (Lidocaine) Bupivicaine (Marcaine, Sensorcaine) Topical Cocaine (4%) Tetracaine (Pontocaine) Proparacaine (Alcaine, Ophthaine) Used to produce absence of sensation May be local or topical
Antibiotics Garamycin Neosporin Bacitracin Erythromycin (Ilotycin) Gantrisin Gentamycin Sulfacetamide Tobramycin Prevent or treat infection May be drops or ointment Injected or Topical
Mydriatics/Cycloplegics Mydriatics Neo-synephrine (Phenylephrine) Atropine sulfate (Atropisol) Dilation of the pupil (mydriasis)by paralyzing iris muscle Cycloplegics Cyclopentolate (Cyclogyl) Tropicamide (Mydriacyl) Dilation of pupil by paralysis of the iris muscle and paralysis of the accommodation mechanism After administration, compress lacrimal sac 2-3 minutes to avoid systemic absorption These drugs increase IOP (intraocular pressure) and should NOT be given to patients with glaucoma
Vasoconstrictors Epinephrine (Adrenalin) Cocaine Prolongs duration of anesthetic Decreases bleeding Injected or topical Most commonly see epi mixed with lidocaine as one solution (ex. Marcaine with epi)
Dyes Fluorescein sodium (Flu-glo) Rose bengal Lissamine green Indocyanine green (IC green) Marks or colors tissue May be used to diagnose abnormalities (corneal abrasions) or locate foreign bodies May be used to see flow of aqueous humor or demonstrate the lacrimal system’s function
Viscoelastic Agents Sodium Hyaluronate (Healon, Amvisc-Plus, Viscoat) Hydroxypropyl methylcellulose (Occucoat) Thick jelly like consistency Injected into anterior chamber during cataract surgery to maintain chamber expansion and prevent surrounding tissue damage May be used as vitreous substitute May be used for tamponade (compression)
Enzymes Protein that act as catalyst (speed up chemical reactions) Alpha-Cymar and Zolyse two most commonly used Increases absorption and dispersal of the anesthetic agent Wydase (hyaluronidase) was phased out in 2001 due to quality assurance issues Wydase was replaced with Vitrase a hyaluronidase product that comes from sheep testicles
Positioning Supine Non-operative side arm on an arm board Operative side tucked Pillow or headrest (may use donut) under head Pillow under knees Heel protectors
Prep Eyebrows never shaved unless surgeon requests (do not grow back completely) Lashes trimmed per surgeon orders with fine scissors coated in petroleum to catch lashes Eyelids and peri-orbital areas cleaned with non- staining antiseptic May flush conjunctiva with BSS or benzalkonium chloride Eyes should be shut during pre may protect with sterile plastic sheet
Draping Likely have entire face exposed even if surgery is unilateral for comparison Head drape or towel and medium sheet place under patient’s head, bring around on either side criss- crossing at hairline or forehead, fasten with clip Towels around face Fenestrated eye drape to expose operative eye Bottom/body sheet for rest of patient Sterile plastic drapes placed over towels or cloth drapes to prevent lint
Equipment Microscope Diathermy probe/apparatus Cryotherapy unit/probe Endocoagulator (bipolar or wet-field) Occutome Argon laser Endoilluminator Bipolar unit Check all equipment prior to use
Instruments Specialty surgeon microscopic eye trays See pgs in your AST text for a list of instrumentation See Rutherford as well
Supplies Eye pack Basin set Disposable eye drape/sterile plastic adhesive drape Microscope drape Pre-cut cellulose sticks (weck cells) Suture 4-0 to 12-0 gauged monofilament nonabsorbable and absorbable (see Table 16-2 in AST text) Needles: (see Table 16-1 in AST text) Round bodied Round bodied with cutting tip Reverse cutting Spatulated Beaver blades Eye patch for dressing
Special Considerations Lint free towels/drapes Will function as ST and STFA Imperative to be able to anticipate surgeon needs due to most patients are awake and quiet is preferable Handle sutures carefully and as little as possible Take care with delicate instrumentation Familiarize self with use of all ophthalmic equipment before attempting to use Meticulously REMOVE powder from gloves to prevent corneal abrasions!
Strabismus Correction Strabismus is a visual disorder where the eyes are misaligned and point in different directions.
Scleral Buckle Scleral buckling surgery is the most common way to treat retinal detachment.
Enucleation Enucleation is the surgical removal of the eyeball that leaves the eye muscles and remaining orbital contents intact.
Evisceration The surgical removal of the contents of the eye, leaving the white part of the eye and the eye muscles intact. This is done to relieve a blind and painful eye due to injury and/or infection when the eye is completely destroyed and blind.
Keratoplasty a surgical procedure in which part or all of a damaged or diseased cornea is replaced by healthy corneal tissue from a donor cornea; transplant to treat Keratoconus (abnormal cone-shaped protrusion of the cornea of the eye)
Cataract Extraction Cataract surgery is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract.
Vitrectomy Vitrectomy is a surgery to remove some or all of the vitreous humor from the eye. Anterior vitrectomy entails removing small portions of the vitreous from the front structures of the eye - often because these are tangled in an intraocular lens or other structures. Pars plana vitrectomy is a general term for a group of operations accomplished in the deeper part of the eye, all of which involve removing some or all of the vitreous - the eye's clear internal jelly.
Pterygium Surgery (pronounced tur-IJ-ee-um) conjunctival removal A pterygium growing across the cornea can cause distortion, resulting in impaired vision. In advanced cases, a pterygium can cover the pupil, causing visual loss