Essentials of Orthokeratology

Transcription

1 Essentials of Orthokeratology Essentials of Orthokeratology Disclosures: Alcon Bausch + Lomb Contamac CooperVision Johnson & Johnson SpecialEyes Valley Contax Matthew J. Lampa, OD, FAAO lampa@pacificu.edu Early Attempts to Reduce Corneal Curvature Ancient Chinese used sandbags on eyes at night to flatten corneal curvature. Evolution of Orthokeratology 1960 to 1990 Keratometry 1990 to Today Corneal Mapping Contemporary OK / Corneal Reshaping Reverse geometry lens designs. Stable, high Dk lens materials. Overnight reshaping modality. Instruments for detailed topographic analysis. Improved fitting techniques. Greater understanding as to how OK works. How Does It Work??? Epithelial Redistribution??? 1

2 9/28/17 Control Control Epithelial Cell Compression Intercellular Fluid Transfer Gap Junctions: Small protein channels that permit cell contents to move from one cell to another. Mid-peripheral Epithelium Normal Central Epithelium Compression Control Control 2

3 #1 Epithelial Cell Retention? #2 Peripheral Cell Migration? 14 Days Post CRT Alterations in cell apoptosis Decreased cell sloughing Increased cell mitosis Axial Display Tangential Display OK How It Works Cellular compression with intercellular fluid transfer Increased cell mitosis Increased cell retention Localized stromal remodeling? Multifactoral Methods Jennifer Choo et.al. 15 Two-year old cats Randomly fitted with myopic OK and Alignment fitting GP lens Same diameter: 12.3 mm Same thickness: 0.16 mm Slit Lamp Examination Corneal Topography To confirm appropriate corneal changes 3

4 Normal Cat Epithelium Right Eye Left Eye Four Week Epithelial Thickness Changes Control Jennifer Choo OD PhD LM Post Corneal Reshaping Left Eye LM Tangential Display Change in Epithelial Thickness Pre Post Jennifer Choo OD PhD 4 weeks 8.4 microns 4

5 9/28/17 Axial Power Display D. Change 5.0 mm Treatment 50 microns Munnerlyn Formula Depth of the Treatment Zone Equals Optical Zone Diameter ² X Refractive Error 3 Treatment Zone Diameter = 5.0 mm OZ Squared 5.0 x 5.0 = 25 Times the Refractive Error = D. 125 Divided by 3 = 42 Tissue Change = 42 microns Munnerlyn Formula 5.0 mm Treatment Depth of the Treatment Zone Equals Optical Zone Diameter ² X Refractive Error 3 Treatment Zone Diameter = OZ Squared 2.0 x 2.0 = Times the Refractive Error = 5.0 mm Pupil Divided by 3 = Tissue Change = Munnerlyn s Formula -5.00D. Treatment Zone 1.0 mm 2.0 mm 3.0 mm 4.0 mm 5.0 mm 6.0 mm Amount of Tissue Change 2 microns 7 microns 15 microns 27 microns 42 microns 60 microns 2.0 mm D microns Scanning Electron Microscopy Average Human Hair 75 microns thick SEM 100 X 5

6 Scanning Electron Microscopy Average Human Hair 75 microns thick Patient BY D. Change 7 microns Pre-Fit Post-Fit 1000 X The Reversibility of Corneal Reshaping Recovery of Epithelial Changes Week Discontinue Lens Wear 1 Day 1 Week 4 Week Lens Designs for Corneal Reshaping Corneal Refractive Therapy BE Design Contex E System DreimLens Emerald Design NightForm Controlled Kerato-Reformation R&R Design NightMove Vipok Fargo Design OrthoFocus Wave System Reversible Corneal Therapy #1 Alignment / Fitting Curve 6

7 #2 Base Curve BOZR #1 Alignment / Fitting Curve #2 Base Curve #3 Reverse Curve #1 Alignment / Fitting Curve Current Fitting Techniques Empirical (K s & Rx) Fitting Techniques Topography Fitting Techniques Inventory Fitting Techniques K s 180 / 90 (7.90 / 7.70 mm) Base Curve Radius BOZR 7.90 mm 7.70 mm 7

8 BC / BOZD / Jesson Factor -0MR: sphere Target Rx: D. (-0.75 D.) = 4.25 Flat K : D. (7.90 mm) BOZR: 4.25 FTK = mm Alignment Curve Alignment Curve BC BOZD 8.75 mm D. Corneal Topographers CZM Atlas 9000 Keratron Scout/Piccalo Medmont Studio Oculus EasyGraph/Keratograph Tomey TMS 1-4 Alignment Curve 7.90 mm D D. Base Curve. BOZR mm Alignment Curve D 7.90 mm 5 microns Reverse Curve Alignment Curve 8

9 Current Fitting Techniques Laboratory (K s & Rx) Fitting Techniques Topography Fitting Techniques Inventory Fitting Techniques Topography Based OK Systems Centered Central Smiley Treatment Island Face Current Fitting Techniques Laboratory (K s & Rx) Fitting Techniques Topography Fitting Techniques Inventory Fitting Techniques Anatomy Of the CRT Lens Pre-Fitting Corneal Topography for CRT Patient SW Return Zone Depth Base Curve Landing Zone Angle 6.0 mm OZ 9

10 Patient SW K s: OD / 163 / OS / 174 / / 084 Rx: OD x /20 6/6 OS x /20 6/6 Patient SW Dispensing Visit Right Eye Left Eye Overnight Lens Wear Overnight Lens Wear Opt Optimum Fitting Relationship 10

11 Patient SW AM Visit Right Eye Left Eye Inadequate Sagittal Depth Too Shallow Return Zone Depth BC.525 RZD.550 RZD 11

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13 Astigmatism Management.75. D (0.15 mm) of Corneal Astigmatism x Incomplete Astigmatism Limbus-to-Limbus Incomplete/Central Limbus-to-Limbus 1.50 D. Corneal Cylinder 1.50 D.Corneal Astig 1.87 D Corneal Astig. 13