general CL topics Flashcards
it is a thin lens considered to be a medical device placed directly on the surface of the eye
Contact Lens
Indications for Contact Lens:
- Any refractive error specially in:
- High refractive errors
- Irregular astigmatism
- anisometropia
- Aphakia
- Keratoconus
- Corneal protection in corneal healing
- Occupational Requirements
Contra-indications for contact lens:
- Anterior segment infection / inflammation
- Chronic ocular allergy
- Certain systemic diseases
- Ptosis
- Corneal hypersensitivity
- Dry eye
- Poor tear quality
- Certain occupations
- Non-compliant patient
- Un-motivated patient
- Poor hygiene
Advantages of Contact Lens:
- Unrestricted peripheral field
- Real image size
- No spectacle reflection
- Cosmetically rewarding
- More comfortable
- Convenient for sports and some occupational activities
- Can be used to
- Correct medical condition
- Protect cornea
- Administer topical drugs to the eye
Disadvantages of Contact lens:
- Potential health risk if not worn / cared for as instructed
- Minor inconvenience of follow up exams
- Cost more
Classification of Contact lens:
- According to Material
- According to Design
- According to Size
- According to Mode of Use
- According to Purpose
Contact lens according to Materials:
Hard :
- non gas permeable
- Gas permeable
Soft :
- Hydrogel
- Silicon Hydrogel
Contact Lens according to Design:
- Monocurve
- Bicurve
- Tricurve
- Aspheric
Contact Lens according to Size:
- Corneal
- Semi-Corneal
- Scleral
Contact Lens according to Mode of use:
Daily wear:
- Disposable
- Planned Replacement
Extended wear:
- Continuous wear
- Flexible wear
Contact Lens according to Purpose:
Optical :
- Spherical
- Toric
- Presbyopic
Therapeutic
Cosmetic
- used to correct myopia, hyperopia, aphakia and small amount of astigmatism
- Available in wide range of correction (-20.00D to +20.00D)
Spherical Contact Lens
For the correction of significant amount of astigmatism
Toric Contact Lens
- Provide the patient with the ease and convenience of continuous wear without cleaning for extended periods of time
Extended Wear SCL
Contact Lens for Presbyopic correction:
- Monovision or Monofit
-
Bifocal soft contact lens:
- Alternating Vision
- Simultaneous Vision - Multifocal:
- Center near design
- Center distance design
- Modified monovision (Balanced Design)
One eye is fitted with the proper distance vision power and the other eye is fitted with the power necessary for near vision.
Monovision or Monofit
- Distance viewing is done through the top part of the lens and near viewing is done through the bottom portion of the lens
Alternating Vision - Bifocal SCL
- The patient looks through both the distance and near portion of the lens at the same time
Simultaneous Vision - Bifocal SCL
kinds of Tinted contact lenses:
- Visibility tint
- Opaque colored lenses
- Combination of transparent and opaque tint
- Effective on blue and other relatively light colored eyes
- Makes handling easier
Visibility Tint
Lenses that can actually change the apparent color of the eye by making the original color masked while introducing a new color
Opaque Colored CL
Enhances eye color by allowing the natural color of the eye to mix with the color of the contact lens
Combination of transparent and opaque tint CL
Modern Contact Lenses:
- Ortho - K contact lens
- Hybrid Contact lens
- Google contact lens
- Triggerfish contact lens
- Wink activated telescope contact lens
- Triggerfish contact lens
- iOptik contact lens
- Terminator Eyes contact lens
a gas permeable contact lenses that temporarily reshape the cornea to reduce refractive errors such as myopia, hyperopia and astigmatism
Ortho-K contact lens
large-diameter lenses that have a rigid gas permeable central zone, surrounded by a peripheral zone made of soft or silicone hydrogel material
Hybrid Contact Lens
contact lens prototype that monitors glucose levels in tears
Google contact lens
- 1.55 millimeter-thick contact lens contains an extremely thin, reflective telescope, which is activated by winks.
- The wearer winks with the right eye to activate the telescope (2.8x magnification), and with the left eye to deactivate it.
Intended for for low vision and age-related macular degeneration
Wink activated telescope contact lens
- a soft disposable silicone contact lens embedding a micro-sensor that measures intraocular pressure
The SENSIMED Triggerfish contact lens
- enhances vision and enables visualize their digital world at the same time.
- It allows light from the display to pass through the center of the pupil, and light from the surrounding environment to pass through the outer portion of the pupil.
- Each of these sets of light rays produces an image on the retina simultaneously with the other set. They are superimposed to form a single integrated image.
iOptik™ contact lens
- show images such as road directions or projecting text messages from smart phones straight to the eye
Terminator Eyes Contact lens
- Provide excellent physiological response for patients with refractive errors in the -1.00
- Has lower protein uptake tendencies which contributes to longer lens life
Low Water Content Lenses
- Contact lens that has higher tensile strength
- Exhibits good material stability
- no problems with discoloration
Low water content contact lens
- High oxygen permeability
- excellent choice for the thicker plus and minus lenses
- Low tensile strength
High Water content contact lens
- not compatible with all disinfecting systems
- High incidence of acute red eye and lens discoloration
High water content contact lens
- Typically ionic or non-ionic materials
- combine best of both high and low water materials
- provide good physiology
- produced in thin comfortable designs
Mild Water Content contact lens
Manufacturing process of CL:
- Spincasting
- Lathe Cutting
- Cast molding
