Gas permeable problem solving
Download
1 / 24

GAS PERMEABLE PROBLEM SOLVING - PowerPoint PPT Presentation


  • 62 Views
  • Uploaded on
  • Presentation posted in: General

GAS PERMEABLE PROBLEM SOLVING. GP PROBLEM SOLVING. Progress Evaluation Procedures Reduced Visual Acuity Decentration Reduced Surface Wettability Power Change Corneal Desiccation Refitting into GPs. GP PROBLEM-SOLVING. Progress Evaluation Procedures. PROGRESS EVALUATION PROCEDURES.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

GAS PERMEABLE PROBLEM SOLVING

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


GAS PERMEABLE PROBLEM SOLVING


GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity

  • Decentration

  • Reduced Surface Wettability

  • Power Change

  • Corneal Desiccation

  • Refitting into GPs


GP PROBLEM-SOLVING

  • Progress Evaluation Procedures


PROGRESS EVALUATION PROCEDURES

  • Lenses On:

    • Visual Acuity

    • Retinoscopy (OR)

    • Sphere-Cylinder

    • Biomicroscopy

      • Lag

      • Surface Quality

      • Edema


PROGRESS EVALUATION PROCEDURES

  • Lenses Off

    • Biomicroscopy

      • Staining

      • Limbal Vasculature

      • Lids

        Keratometry

        Subjective

        Verification


GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity


REDUCED VISUAL ACUITY

  • Flexure

  • Warpage

  • Decentration

  • Reduced Surface Wettability

  • Power Change


REDUCED VISUAL ACUITY

  • Flexure:

    • Bending of a flexible GP lens on a toric cornea

    • Diagnosed via over-K’s; if toric & radiuscope is spherical = flexure

    • Managed via flatter BCR, smaller OZD &/or increased center thickness


REDUCED VISUAL ACUITY

  • Flexure

  • Warpage:

    • Caused by excessive digital pressure, especially with high Dk material & digital cleaner


REDUCED VISUAL ACUITY

  • Flexure

  • Warpage

  • Decentration: Causes include:

    • Lens Design

    • Lens Material

    • Corneal Topography

    • Lid Tension/Blink Quality


REDUCED VISUAL ACUITY: DECENTRATION

  • Complications:

    • Reduced/Variable Vision & Flare

    • Limbal Irritation/ 3 & 9 staining

    • Lens Awareness

    • Lens Dislocation

    • Poor Corneal Alignment; excessive flattening & steepening with possibility of distortion


REDUCED VISUAL ACUITY: INFERIOR DECENTRATION

  • Management:

    • Reduce Center Thickness

    • Proper Edge Design (- lent < -1.50D/+); +lent. > -5.00D

    • Bitoric > 2.50D corneal cyl

    • Lid Attachment Design


REDUCED VISUAL ACUITY: LATERAL DECENTRATION

  • Causes: ATR Cyl./ displaced corneal apex

  • Management: Increase OAD or Steeper BCR; aspheric design


REDUCED VISUAL ACUITY

  • Flexure

  • Warpage

  • Decentration

  • Reduced Surface Wettability

  • Power Change


GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity

  • Corneal Desiccation


GP PROBLEM-SOLVING: CORNEAL DESICCATION

  • Definition: Dryness or peripheral desiccation staining occurring in 3 & 9 o’clock regions of the cornea.

  • Occurs in over 50% of rigid lens wearers (but decreasing)

  • Ranges from diffuse punctate staining (most common) to corneal opacification & neovascularization


GP PROBLEM SOLVING: CORNEAL DESICCATION

  • Diameter: larger reduces area; smaller reduces mass

  • Lens Position: Inferior least desirable (Henry, Bennett & Forrest, AJO, 1086)

  • 3 & 9 o’clock staining-to-fit relationship

    • Position#Eyes 3 & 9 %

      Sup-Centr125 48 38

      Interpalp193 111 57

      Inf-Centr 46 34 73


CORNEAL DESICCATION

  • Edge Lift: Too small versus too large

  • Center Thickness: Problems of large CT: Verify!

  • Edge Shape: well polished, thin & tapered


GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity

  • Corneal Desiccation

  • Refitting into GPs


REFITTING INTO GPS

  • Complications

    • Edema (98%)

    • Corneal Warpage

    • Corneal Exhaustion


REFITTING INTO GPS

  • Possible Applications (keratoconus, high astigmatism, presbyopia, soft failures, orthokeratology)

  • Liability

    • Explain GP benefits (effects of PMMA wear, O2 permeability, modern technology, vision in spectacles)

    • Audiovisuals: photographs/slides, videotapes


REFITTING INTO GPS

  • Refitting Procedure

    • Immediate refit without loss in wearing time

    • If corneal warpage, reduce wear time to minimum they can wear and refit one week later

    • Same design or new design???


REFITTING INTO GPS FROM SOFT LENSES

  • Most common reasons:

    • GPC

    • Poor Vision


ad
  • Login