Gas permeable problem solving
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GAS PERMEABLE PROBLEM SOLVING PowerPoint PPT Presentation


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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.

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GAS PERMEABLE PROBLEM SOLVING

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Gas permeable problem solving

GAS PERMEABLE PROBLEM SOLVING


Gp problem solving

GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity

  • Decentration

  • Reduced Surface Wettability

  • Power Change

  • Corneal Desiccation

  • Refitting into GPs


Gp problem solving1

GP PROBLEM-SOLVING

  • Progress Evaluation Procedures


Progress evaluation procedures

PROGRESS EVALUATION PROCEDURES

  • Lenses On:

    • Visual Acuity

    • Retinoscopy (OR)

    • Sphere-Cylinder

    • Biomicroscopy

      • Lag

      • Surface Quality

      • Edema


Progress evaluation procedures1

PROGRESS EVALUATION PROCEDURES

  • Lenses Off

    • Biomicroscopy

      • Staining

      • Limbal Vasculature

      • Lids

        Keratometry

        Subjective

        Verification


Gp problem solving2

GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity


Reduced visual acuity

REDUCED VISUAL ACUITY

  • Flexure

  • Warpage

  • Decentration

  • Reduced Surface Wettability

  • Power Change


Reduced visual acuity1

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 acuity2

REDUCED VISUAL ACUITY

  • Flexure

  • Warpage:

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


Reduced visual acuity3

REDUCED VISUAL ACUITY

  • Flexure

  • Warpage

  • Decentration: Causes include:

    • Lens Design

    • Lens Material

    • Corneal Topography

    • Lid Tension/Blink Quality


Reduced visual acuity decentration

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

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

REDUCED VISUAL ACUITY: LATERAL DECENTRATION

  • Causes: ATR Cyl./ displaced corneal apex

  • Management: Increase OAD or Steeper BCR; aspheric design


Reduced visual acuity4

REDUCED VISUAL ACUITY

  • Flexure

  • Warpage

  • Decentration

  • Reduced Surface Wettability

  • Power Change


Gp problem solving3

GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity

  • Corneal Desiccation


Gp problem solving 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 desiccation1

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

CORNEAL DESICCATION

  • Edge Lift: Too small versus too large

  • Center Thickness: Problems of large CT: Verify!

  • Edge Shape: well polished, thin & tapered


Gp problem solving4

GP PROBLEM SOLVING

  • Progress Evaluation Procedures

  • Reduced Visual Acuity

  • Corneal Desiccation

  • Refitting into GPs


Refitting into gps

REFITTING INTO GPS

  • Complications

    • Edema (98%)

    • Corneal Warpage

    • Corneal Exhaustion


Refitting into gps1

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 gps2

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

REFITTING INTO GPS FROM SOFT LENSES

  • Most common reasons:

    • GPC

    • Poor Vision


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