CHEM 3B Midterm: The Optometry 10 Study Guide Spring 2016
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Chemistry
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CHEM 3B
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stevenpedersen

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1 The Opt 10 Study Guide- Important Terms and Concepts Revised by Tracy Nguyen and Tina Zeng (Spring Semester 2016 ) Original by Mark Landig, O.D UC Berkeley, Class of 2013 1. The Eye and Sight, Dr. Yu Important Terminology 1. Color Blindness - Inability to distinguish between some colors, most common is difficulty distinguishing shades of red and green. Usually hereditary. 2. Depth Perception - Ability to see in 3-Dimensions. A patient who does not have depth perception sees images as “flat” (i.e. cannot determine one object is in front of another). 3. Electromagnetic Radiation - Energy that travels and spreads as it goes. Examples are visible light, radio waves, microwaves, infrar ed, ultraviolet light, X -rays, and gamma-rays. a. Visible Spectrum - Portion of EM spectrum that is visible (human eye can detect). Typical human eye can respond to wavelengths from 380 -750nm. b. R.O.Y.G.B.I.V. 4. Peripheral Vision - Side vision, not central visio n. 5. Visible Spectrum - A type of electromagnetic radiation that is visible (i.e. capable of detection by the human eye). Mark Landig | 2012 2 Main Eye Landmarks 1. Anterior Chamber - Fluid Filled Space inside the eye between the cornea and the iris. 2. Aqueous Humor - Clear, watery fluid that fills the space between the cornea and the front of the vitreous, bathing and nourishing the lens, iris, cornea. AH maintains the eye ’s Intraocular pressure (IOP). 3. Blind Spot - Sightless area within the visual field of a normal eye. Cau sed by absence of light sensitive photoreceptors where the optic nerve enters the eye. 4. Blood vessel - an artery, vein, or a capillary, through which the blood circulates. 5. Choroid - Layer of large blood vessels lying between the retina and the sclera, which provides nourishment to the retina. 6. Cones - a photoreceptor located in the retina used for color vision and which provides sharp visual acuity. A normal retina contains about 6 to 7 million cones. There are 3 types: a. Short wavelength cones: respond best to blue. b. Medium wavelength cones: respond best to green and yellow. c. Long wavelength cones: respond best to red and yellow. 7. Conjunctiva - Transparent mucous membrane covering the outer surface of the eyeball, except the cornea. 8. Cornea - Transparent front part of the eye that covers the iris, pupil and anterior chamber and provides most of the eye’s optical power. 9. Crystalline Lens - Transparent oval tissue that helps bring rays of light to focus on the retina. 10. Eyebrow - The bony ridge covered by an arch of short hairs. 11. Eyelids - Protective structure covering the front of the eye. 12. Fovea - Central area within the macula that produces the sharpest, detailed vision. 13. Iris - Pigmented tissue lying behind the cornea that gives color to the eye (i.e. blue eyes). The iris also controls pupil size. 14. Lacrimal Gland - A gland that secrete tears. 15. Lacrimal Puncta - Small circular openings, which allow for drainage of tears. 16. Macula - Small, central area of retina surrounding the fovea used fo r detailed, central vision (driving, reading etc.) 17. Optic disc/optic nerve head - The optic disc is a small, circular region where the retinal nerve fibers exit the eye as the optic nerve and where blood vessels enter and exit the eye. 18. Optic Nerve - Eye’s connection to the brain, which carries impulses for sight from the retina to the brain. 19. Orbit - Boney socket that encompasses the eye. 20. Pupil - variable-sized opening in the center of the iris that regulates the amount of light into the eye. Parasympathetic and Sympathetic Nervous Systems control pupil size via pupillary muscles. 21. Retina - Light sensitive nerve tissue that lines the back of the eye and connects to the brain via the optic nerve. It converts images from the eye’s optical system into electrical impulses that are sent along the optic nerve to the brain. 22. Rod - A Photoreceptor responsible for vision at low light levels, night vision , and peripheral (side) vision. A normal retina contains about 120 million rods. Rods are more sensitive than cones. 23. Sclera - white, opaque, protective covering. 24. Vitreous body - Also known as vitreous humor - the clear gel filling the inner, rear portion of the eyeball between the lens and retina. Mark Landig | 2012 3 Binocular Vision Binocular- Using both eyes at the same time. Diplopia- Double vision. Usually an extraocular muscle problem caused by cranial nerve damage. Extraocular Muscles - Six Muscles that move the eyeball Medial Rectus (MR) Moves eye inward towards the nose. Lateral Rectus (LR) Moves eye outward, away from nose. Superior Rectus (SR) Primarily moves the eye upward. Inferior Rectus (IR) Primarily moves the eye downward. Superior Oblique (SO) Primarily rotates the top of the eye toward the nose. Inferior Oblique (IO) Primarily rotates the top of the eye away from the nose. Normally, eyes should be pointing accurately towards an object. However, eyes can be misaligned: in, out, up, or diagonal. Esotropia- Eye is turned inwards, naturally. Exotropia- Eye is turned outwards, naturally. The Eye Socket-Orbital Bones The eye is housed in a cavity of orbital bones and protected by surrounding muscles and tissue: The 7 Orbital Bones: 1. Frontal bone, 2. Lacrimal bone, 3. Ethmoid bone, 4. Zygomatic bone, 5. Maxillary bone, 6. Palatine bone, and 7. Sphenoid bone. 2. The Eye Professionals, Dr. Harvey History • Early Cavepersons o Trephination – drilling holes into the head was used for cases (epilepsy, mental illness, severe headaches) to “release evil spirits” • Hippocrates (460-377 BC) o Father of Medicine o Developed humoral theory that attributed disease to the various fluids of the body: § Disease was caused by phy sical causes rather than demons o Documented sign and symptoms and analyzed possible causes and associati ons (the Principle of Epidemiology) o Developed ethical principles—the physician’s primary obligation was to the patient (Hippocratic Oath – will do no harm to the patient ) • Medicine in the Middle Ages o Period between the decline of Rome a nd the beginning of the Renaissance o Western Europe : raids and wars, cities were walled in defense which became filthy and disease-ridden; very little advancement in medicine o The Black Plague § Transmitted from rats to humans by infected fleas § Killed about 20-30 million people in Europe, which is 25-33% of the population § Medical Care: • Doctors dressed in outfits to keep them safe when treating those infected with plague • Physicians were not very helpful. o Most common method of curing the plague was bloodletting. Mark Landig | 2012 4 § Cuts were made in various parts of the body and the blood drained out. o The Renaissance Period § The end of the Dark and Middle Ages and the beginning of times of medical and scientific discoveries a s well as cultural advancement § Problems of Surgery • Pain and infections o Anesthesia § 1830s-40s, ether frolics and la ughing gas parties were popular § Physician used ether on party -going patient who was reluctant to hav e a tumor removed from his neck § Its success quickly spread to the rest of the world and was used for dental and surgical procedures. o Antisepsis and Sanitation § Joseph Lister (1827-1912) • Was impressed by Pasteur’s work and felt bacteria was in the air and around patients • Developed antisepsis o Greatly decreased mortality from surgery. § Florence Nightingale (1820 -1910) • Created new standards for the care of wounded and sick o Decreased mortality rate. • Founded the first school of nursing. o Development of Glasses § Convex Lenses – Presbyopia 1285AD § Concave Lenses — Myopia 1480 AD § Bifocals lenses – prescription for distance and near 1785 AD § Cylindrical lenses—Astigmatism 1825 AD • Early Opticians/Optometrists o Opticians § Early spectacle peddlers traveled around America with prefabricated glasses. o Opticians divided into 2 groups: § Dispensing Opticians à opticians § Refracting Opticians à optometrists The Three O’s • Opticians o Dispense glasses o Can’t write prescription for glasses (or contacts) • Optometrists o Check for visual acuities o Refraction o Optional = specialize § Refraction Advanced Techniques § Contact Lenses § Pediatrics, Vision Therapy § Ocular and Systemic Health o Serious Surgical Co-Management o Minor Surgery (i.e. foreign Body removal) • Ophthalmologists o MDs and most often conducts surgery Mark Landig | 2012 5 3. Myopia, Hyperopia, Astigmatism, Dr. Moy • Light Basics o Point sources create diverging light o Convex Lens will converge light. o Concave lens will diverge light • Emmetropia o Parallel light enters and focus on the retina • Myopia (nearsighted ness) o Parallel light focuses in front of retina o Axial length is too long o Cornea or lens too strong o 88% genetic and 12% environment § Due to axial length! § Case study on twins: Genetics of myopia à % both identical twins myopia>> % of both fraternal twins myopia. o Correcting Myopiaà MINUS lens • Hyperopia (farsighted ness) o Parallel light focuses behind the retina o Most hyperopes don’t need glasses § AccommodationàCiliary body contractà Distance between the muscle and lens decreases (zonules slacks) à lens curvature increasesà moves light focus (focal point) forward to the retina • When we focus at nearà we accommodate. o Correctionà PLUS lens • Presbyopia o Eye’s ability to focus (via the crystalline lens) decreases with age o Mechanism § Every year, another layer of cells is added to the lens § Lens flexibility DECREASES § Ability to change lens sha pe DECREASES o Correctionà Glasses (Bifocals/Trifocals/Progressives ) Mark Landig | 2012 6 • Cataract o Opacity in the crystalline lens o Surgically removed when it affects vision § Plastic lens is inserted • Astigmatism o Cornea is not perfectly spherical § Shaped like a football. § One meridian is steeper than the other. These two meridians are often 90 degrees from each other. Case: Headaches and tired when reading for a long period of time. What do you think this person’s refractive error is? Hyperopia. Surgery • Radial Keratotomy (RK) — corrects myopia o Weakens the eye structurally o Complication due to incisions can arise o Not accurate o Hard to fit CL post -surgery • Photorefractive Keratectomy (PRK) o Epithelium is removed & the outermost layer below the epithelium is treated with laser. § Very painful recovery period § Permanently weakens the eye structure § Chance of scarring is high § Working directly over visual axis • LASIK o Similar to PRK but flap cut instead. o Much more predictable , not really painful o Maintains eye strength o Complications are low , but minor complications include: § Dry eyes are a side affect § Halos around lights at night. 4. Eye and vision function—from birth to preschool, Dr. Orel -Bixler Newborn’s Eye -Human neonate visual system is relatively mature at birth -Growth of the eye and improvement of vision is rapid during the first year of life -Formation begins at 22 days of fetal life -6 weeks post-conception: ocular structures and differentiation of brain fairly well developed Teratogenic Factors Teratogen: a drug or other agen t that causes abnormal fetal development st -drug abuse, infection, meds in 1 trimester result in ocular defects, alcoholism Eye Growth -Newborns eye is 2/3 of adult size (diameter is like a dime vs. quarter in adults) -Growth in both axial & equatorial directions (axial length increases most rapidly during first 2 years) -Anterior structures more developed than posterior at birth Mark Landig | 2012 7 Cornea -Clear within 2 days after birth -Rapid decrease in curvature after 1 st(astigmatism decreases in 1 styear) -Term infants: ~10mm diameter -Abnormal 9mm
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