Ophthalmic Surgery

1. Ophthalmic Surgery

2. Outline • Terminology • Anatomy • Pathology • Diagnostics/Testing • Anesthesia • Meds • Positioning/prepping/Draping • Equipment/Instrumentation/Supplies • Considerations • Procedures

3. 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

4. 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

5. 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)

6. Abbreviations • OD oculus dexter = right eye • OS oculus sinister = left eye • OU oculus unitas = both eyes

7. Purpose of Eye Surgery • Preserve or Restore Vision

8. Causes of Eye Defects • Congenital • Injury • Disease

9. Anatomy of the Eye

10. Globe • Eyeball • Compared to a sophisticated camera • All parts work together to produce a clear image (vision)

11. Eyeball • 1” diameter • 3 major layers: 1. Fibrous Tunic • Outer layer/dense connective tissue 2. Vascular Tunic 3. Nervous Tunic

12. 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

13. 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

14. 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

15. 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 Rods and Cones

16. 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

17. 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

18. 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

19. Anterior Cavity • Contains 2 chambers: • Anterior chamber anterior to iris • Posterior chamber posterior to iris • Both contain aqueous humor

20. 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

22. 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)

23. 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 Intrinsic Eye Muscles Muscles located inside the eyeball Includes: Iris Ciliary body Eye Muscles

24. 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

26. Nerves and Blood Supply • 2nd cranial nerve (optic nerve) vision • 3rd cranial nerve (oculomotor) 1° motor nerve medial rectus, inferior rectus, superior rectus, and inferior oblique muscles • 4th cranial nerve (trochlear) superior oblique • 6th 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

29. 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

30. Physiology of Accommodation (Focus) http://www.youtube.com/watch?v=15P8q35vNHw

31. Pathology

32. 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

33. 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 Retinal Detachment

34. Vitreous Hemorrhage • With retinal tear, blood vessels torn and vitreous hemorrhage occurs • Vitrectomy must be performed to determine if a retinal tear has occurred

35. (PVR)Proliferative Vitreoretinopathy • Occurs 5-10% post-scleral buckle (procedure performed to repair detached retina) • Scarring pulls on retina creating re-detachment

36. Epiretinal Membrane • Scarring over the macula (area of retina where vision most accurate) results in a cloudy appearance • Membrane is removed surgically

37. 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)

38. 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

39. 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

40. 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 Strabismus

41. 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

42. Entropian • Inversion (turning in on itself) of the lower eyelid

43. Ectropion • Eversion (turning out) of the lower eyelid

44. 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

45. Anesthesia • General (children, selected patients) • Retrobulbar Block • Both • Local • Idea to keep eye completely still and lower intraocular pressure

46. 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

47. 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

48. Antibiotics • Garamycin • Neosporin • Bacitracin • Erythromycin (Ilotycin) • Gantrisin • Gentamycin • Sulfacetamide • Tobramycin • Prevent or treat infection • May be drops or ointment • Injected or Topical

49. Steroids Dexamethasone (Decadron, Maxidex) Betamethasone (Celestone) Prednisone (PredForte, PredMild) NSAIDS Ketorolac (Acular) Diclofenac (Voltaren) Flurbiprofen (Ocufen) Suprofen (Profenal) Reduce inflammation and prevent edema Injected or Topical Anti-inflammatories

50. Irrigants • BSS balanced salt solution • Tis-U-Sol balanced salt solution • Lacrilube • Duratears • Lactated Ringer’s solution • Irrigate anterior chamber • Keep cornea and eye tissue moist • Soak and rinse intra-ocular lens