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Flashcards in Vision Correction Deck (18)
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Methods of Correcting vision problems

-corrective lenses
-contact lenses
-surgical correction


Refraction def

bending of light rays as they pass from one transparent medium through another of different density


-corrective lens type

concave spherical, minus and divergent


-corrective lens type

convex, plus and convergent


-corrective lens type

-corrected w/ spherical lens


Myopia & astigmatism
-corrective lens type

Hyperopia & astigmatism
-lens type

-concave divergent and spherical lens

-convex converging and spherical lens


Refractive Keratoplasty
-what is this?

generic term that includes all surgical procedures on the cornea to improve vision by changing the shape, and thus the refractive index of the corneal surface.

-Keratotomies= corneal incisions
-keratectomies= removal of corneal epithelium
-keratomileusis= reshaping a stromal layer of the cornea.


Patient Selection of Surgery
- general CI

-autoimmune, collagen vascular and immunodeficiency disease affect corneal healing
-pregnant women/nursing (must wait 1 year after breastfeeding)
-pts w/ abnormal wound healing (keloids
-Diabetes Mellitus (can perform if well controlled, without cataract or diabetic retinopathy)


Patient Selection of Surgery
-Ocular CI

-keratconjunctivitis sicca (really really dry eyes)
-exposure keratitis
-neurotrophic kerratitis
-lid disorder affecting tear layer
-patient w/ hx of herpetic keratitis
-pt w/ abnormal cornea
-severe rosacea

*essentailly if you have


Radial Keratotomy
- first commonly used for what vision correction
-what is this procedure?

-first commonly practiced in myopia, though not used much anymore.

-incision created produce bulge in peripheral portion of cornea which flattens the central cornea. Done in both eyes, wait 6wks in-between.


-what does this stand for?
-corrects which type of vision
-explain this procedure.
-compare to PRK (photorefractive keratotomy)

laser in-situ Keratomileusis

- myopia and hyperopia, astigmatism

-uses excimer laser to resect corneal flap and then either steepen(hyperopia) or flatten a too steep cornea(myopia), return original corneal flap.

*similar to PRK except corneal epithelium remains intact
*much faster recovery


Disadvantages & Advantages to LASIK

-changes made to cornea are irreversible.
-technically complex
-can rarely cause a loss of best vision (which is best corrected vision with glasses or contacts)
-costs $500-1000

- 90% will have desired vision
-very little pain
-vision corrected nearly immediately
-no bandages/stiches
-adjustments can be made years after



-see halos around images
-difficulty driving at night
-fluctuating vision
-dry eyes


Photorefractive Keratoectomy (PRK)
-what type of vision correction?
-describe procedure.
-compare to LASIK
-circumstances in which this procedure is preferred

-myopic, hyperopic, astigmatism

-laser removes part of outside cornea, reshaping the eye to correct refractive errors.

-recovery is longer and more painful than LASIK, longer to see final results

-when pt have thin or irregular shaped corneas or evidence of scarring


-describe procedure

- cut thin corneal flap. few drops of 20% alcohol solution instilled and left on cornea for 30seconds, this is washed and dried. eximer laser treats the stroma just like in LASIK

-thinner corneal flap may avoid corneal ectasia
-LASIK requires more complicated equipment
-risk of infection are easier to manage with thinner flap.

-thin corneal flap may dislodge post-op causing greater pain
-slower optical recovery time
-can cause stromal haze in treated myopic pt


-used to correct what type of vision
-how is this performed?

-hyperopia & presbyopia

-eliminates the chance of developing cataracts.

-natural lens of eye is removed and replaced with plastic lens. this lens works with the eye muscles and change focus natrually.

-small incision lens rolled into capsule, resected and replaced with plastic lens.


-what is this?
-what population is this appealing to?
-what type of vision is corrected?

-non surgical procedure, wear contact lenses at night to slowlyl reshape the cornea overtime to correct myopia.

-teenagers who cant get LASIK



How to improve vision?

-eat nutritously
-eye vitamins:
--Vit A and Beta carotene for night vision, wound healing, and immune function
--Vit B complex (1,2,3,5,6,12, folic acid, biotin, choline) help reduce chronic inflamm, prevent elevated homocysteine levels which has been associate dwith vascular problems affecting the retina. Also, plays role in reducing macular degeneration and tx of uveitis
--Vit C- reduce risk of cataracts
--Vit D- lower risk of macular degeneration
--Vit E lower risk of cataracts
--omega 3 reduce risk of dry eye
--phytochemical antioxidants; gingko, biloba and bilberry may provide protection from oxidative stress in eyes