Chapter 14: Principles and Problems of Contact Lenses Flashcards

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1
Q

Basic Principles

A

1) Determine refractive error (Refraction)
2) Determine flat and steep corneal meridians, and axis
3) Choice of lens type based on medical and ocular history, and specific needs of the patient

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2
Q

Characteristics of Contact Lenses

A

Prescription information:
1) Spherical equivalent, cylinder and axis
2) Diameter of lens
3) Base curve
4) Lens thickness
5) Material, polymer, or brand name
6) Edge blends or peripheral curves
7) Lens tint or lens color
8) Wearing instruction
9) Care regimen
10) Schedule of follow up

Advantages: they do not distort peripheral vision, do not fog, better for certain kinds o refractive errors (high power, keratoconus, nystagmus, irregular astigmatism)

Disadvantages: high maintenance, increased risk of infection, not recommended for certain environments (dust), higher cost, easier to lose

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3
Q

Soft Lenses

A

Flexible contact lenses that permit oxygen and carbon dioxide diffusion through the lens material itself, with minimal tear buildup
Most commonly used lens type today

Advantages: More comfortable, rarely cause spectacle blur, less risk of overwear, less expensive
Disadvantages: variable vision due to dehydration of the lens, less durable

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4
Q

Rigid-Gas Permeable Lenses

A

Contact lenses that permit oxygen and carbon dioxide diffusion through both the lens material and the tear pump

Advantages: More comfortable than PMMA, better suited for problems like keratoconus and irregular astigmatism
Disadvantages: more fragile and prone to protein deposit buildup, more expensive

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5
Q

Spectacle Blur

A

Temporary blurred vision upon switching from contacts to eyeglasses

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6
Q

Polymethyl Methacrylate Lenses

A

Contact lenses that provide oxygen by means of a tear pump only, there is no diffusion through the lens materials

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7
Q

Oxygen-Permeable

A

The ability of a contact lens to transmit oxygen through it material

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8
Q

Extended-Wear Contact Lenses

A

Soft contact lenses that are approved for overnight wear for up to 7 days
Associated with adverse corneal effects and corneal ulcers

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9
Q

Daily-Wear Contact Lenses

A

Rigid and soft contact lenses intended to be worn for fewer than 24 hours consecutively while awake
Associated with oxygen depravation to the cornea if not used as directed

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10
Q

Disposable Contact Lenses

A

Soft contact lenses designed for both daily and extended wear, and then to be discarded after 1-4 weeks

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11
Q

Planned-Replacement Contact Lenses

A

Contact lenses that are designed to be replaced on a regular schedule determined by the ophthalmologist according to patient wearing characteristics and other factors (typically between 1,2,3,or 6 months)

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12
Q

Toric Contact Lenses

A

A contact lens that is specified to correct astigmatism

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13
Q

Bifocal Contact Lenses

A

A contact lens that is multifocal, consisting of a portion that corrects for distance and another portion that corrects for near vision

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14
Q

Monovision

A

An artificially produced system creating visual clarity for near in one eye, and for distance in the other eye. This can be done with either contact lenses or surgically (LASIK or cataract surgery)
There is decreased stereopsis with monovision

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15
Q

Keratoconus

A

A rare degenerative corneal disease in which the center of the cornea thins and assumes the shape of a cone, seriously affecting vision
Will typically have RPG contact lenses prescribed

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16
Q

Corneal Bullous Edema

A

Swelling of the corneal tissue severe enough to cause blisters on the surface of the cornea and decreased vision

17
Q

Care of Contact Lenses

A

1) Cleaning and disinfecting the contacts in order to prevent infection and remove deposits
2) Lubricating the lenses
3) Using the lenses as instructed by the physician
4) Cleaning and Disinfecting
5) Lubrication

18
Q

Enzyme Cleaners

A

A specially designed detergent removing protein deposits from contact lenses

19
Q

Proteolytic Enzymes

A

Enzyme cleaners that are capable of dissolving proteins

20
Q

Triphasic Enzymes

A

A specialized cleaning agent that dissolved adhered substances on contact lenses

21
Q

Surfactant Cleaners

A

A specialized contact lens cleaning solution and wetting agent

22
Q

Insertion of Contacts

A

1) Wash hands
2) Remove lens from case
3) Rinse lens with saline
4) Place lens on tip of index finger
5) Pull down lower eyelid, look up, and place lens on lower portion of globe
6) Close your eyes and massage eyelid to center the lens

23
Q

Removal of Contacts

A

1) Wash hands
2) Look up, pull down lower eyelid and place index finger on lower edge of lens
3) Move lens down the globe
4) Compress lens between finger tips
5) Remove lens
6) Clean lens and place in storage case

24
Q

Problems with Contact Lenses

A

1) Allergies to lens solutions
2) Solution-Contact lens interaction
3) Overwearing syndrome
4) Improper contact lens fitting
5) Giant Papillary Conjunctivitis
6) Irritation and Tearing
7) Corneal edema, vascularization, infiltrates, corneal ulcer, infections, abrasions
8) Inability to remove lenses
9) Losing lens in eye

25
Q

Ciliary Spasm

A

A painful contraction of the ciliary muscle commonly caused by inflammation of the cornea or iris

26
Q

Contact-lens Induced Acute Red Eye

A

Dilation of blood vessels in the conjunctiva caused by contact lens irritation

27
Q

Giant Papillary Conjunctivitis

A

Inflammation of the palpebral conjunctiva, characterized by large-raised bumps on the underside of the eyelids

28
Q

Corneal Edema

A

Swelling of the corneal tissue

29
Q

Corneal Vascularization

A

Abnormal condition charactered by blood vessels growth in the cornea

30
Q

Corneal Infiltrates

A

A discrete collection of inflammatory cells in the cornea

31
Q

Contact Lens Peripheral Ulcers

A

Contact lens-induced noninfectious corneal ulcers outside of the visual axis

32
Q

Corneal Ulcer

A

Pathological condition involving a defect in the corneal surface and associated with inflammation; infectious ulcers are caused by a pathogenic organism

33
Q

Corneal Abrasion

A

A scratch or other defect in the superficial cornea caused by trauma

34
Q

Contraindication

A

Any condition that renders a particular treatment, medication, or medical device inadvisable for a particular patient

1) Ocular pathologic conditions
2) Inability to comply with hygiene regiment
3) poor/no blink reflexes
4) Moderate-severe dry eye
5) Disabilities that limit mobility
6) Occupation
7) Seizures