Contact Lens Handling and Care

Preparation

• Wash hands thoroughly with non-lotion and non-perfumed soap, then dry with a lint-free towel.
• Remove the right lens from storage and rinse with multipurpose solution or sterile saline.
• Inspect the lens for damage and eversion by placing it on the tip of the right index finger.

Insertion

• Use an upright mirror to gaze upwards, lowering the chin to the chest.
• Expose the inferior bulbar conjunctiva by retracting the right lower lid at the lid margin with the right middle finger.
• Retract the right upper lid at the lid margin with the left middle finger.
• Place half the lens on the cornea and half on the inferior bulbar conjunctiva.
• Lower the eyes downwards, and then release the lids slowly.

Removal

• Wash, rinse, and dry hands as previously described.
• Use an upright mirror to gaze upwards, lowering the chin to the chest.
• Retract the right lower lid at the lid margin with the right middle finger.
• Slide the lens downwards with the right index finger, placing half on the cornea and half on the bulbar conjunctiva.
• Pinch the lens lightly between the thumb and index finger to break the suction, and then remove from the eye.
• Inspect the lens for damage, clean, and rinse with the habitual solution before putting it in the case.

Tips for Insertion and Removal

• The lens can be placed directly on the cornea.
• Opening the mouth wide can reduce excessive blinking during insertion.
• Insert lenses before applying cosmetics to minimize debris trapping.
• Use multipurpose solution or soft lens compatible rewetting drops to aid in difficult lens removal.

Cleaning

• Perform digital rubbing on the anterior lens surface by placing it in the non-dominant hand, adding the suggested number of drops, and rubbing back and forth and/or side to side.
• Repeat the process for the posterior lens surface, avoiding hard rubbing that can tear thinner lenses.

Base Curve Radius (BCR)

• BCR can be written in either dioptric power or millimeters (e.g., 45.00D = 7.50mm)
• Measured using a radioscope (e.g., Marco Radiusgauge)
• Procedures to measure BCR:
  • Prepare the lens by cleaning, rinsing, and patting it dry
  • Prepare the radioscope by placing a drop of water or hydrogel multipurpose solution on the concave lens mount
  • Place the lens in the well on the lens mount and center it on the stage
  • Use the coarse adjustment knob to raise the objective until the target form appears
  • Move the stage to center the target and bring it into focus using the fine adjustment knob
  • "Zero out" the inner and outer scales using the knurled knob
  • Record the BCR to the nearest 0.01mm

Power (F)

• Verified using a lensometer
• Measured in the customary manner
• Power in Bitoric and Front Sphere/Back Toric lenses is recorded separately, with the greatest minus or least plus power first and the least minus or greatest plus power second, separated by a slash

Center Thickness (CT)

• Measured using a dedicated thickness gauge or the gauge on the radioscope
• Read only the larger outer dial, marked in increments of 0.01mm
• Record CT to the nearest 0.01mm
• Minus power lenses typically have CTs between 0.10 and 0.20mm, while plus power lenses typically have CTs between 0.20 and 0.40mm

Overall Diameter (OAD) and Optic Zone Diameter (OZD)

• OAD measured using a lens loupe or V-gauge
• Record OAD to the nearest 0.1mm
• OZD determined by measuring the distance between the peripheral curve systems

Peripheral Curve System (PCS) and Peripheral Curve System Width (PCSW)

• PCS width specified in mm (secondary, intermediate, and peripheral)
• Total width of PCS corresponds to only half the lens, so multiply by 2 to describe the total width
• Verified with a lens loupe

Peripheral Curve System Blend

• Verified with a lens loupe
• Classified as Light (L), Medium (M), or Heavy (H) based on the ease of seeing the junctions between the curves

Color

• Standard colors include blue, brown, green, and gray
• Options to help patients identify the right or left lens:
  • A black dot can be inked on the periphery of the right lens
  • Use a gReen or gRay lens for the right eye, and a bLue lens for the left eye

Review of GP Lens Designs

• Determine the type of toric GP lens by calculating the difference between radioscope readings (converted to diopters) and lensometry readings (already in diopters), and then dividing the smaller number into the larger one to obtain a ratio
• Ratios are always the larger number divided by the smaller number
• Use the table to identify the lens design based on the ratio

GP Lens Care System Components

• Cleaner: Removes lipids, mucin, protein, and cosmetics from CL surfaces. Daily cleaning is essential to prevent deposit accumulation.
• Conditioner: Has four functions:
  • Cushioning: Provides comfort between the CL and cornea.
  • Wetting: Makes CL surfaces more hydrophilic for better tear film spread.
  • Disinfection: Safeguards against contamination.
  • Lubrication: Relieves drying and breaks up deposits.
• Hydration: Daily protein remover and periodic enzymatic cleaner for removing protein deposits.
• Lubricant: Relieves drying, rewets, breaks up deposits, and rinses away debris.
• Saline: For rinsing and filling scleral GP and hybrid CLs. Must be preservative-free saline.

GP CL Care Systems

• Chemical Systems: Advantages: good anti-microbial activity, easy to use. Disadvantages: preservatives may cause sensitivity or allergy.
  • One Bottle Multipurpose: Examples include B&L Boston Simplus, Tangible Clean, and Menicon Unique pH.
  • Two Bottle/Multiple Step: Examples include B&L Boston Original, B&L Boston Advance, and Lobob Optimum.
• Oxidative (Hydrogen Peroxide) Systems: Advantages: excellent anti-microbial activity, ideal for patients with preservative sensitivities. Disadvantages: complicated to use, requires neutralization.
  • Examples: AMO Oxycept UltraCare and Alcon Clear Care Plus.
• Protein Removal: Examples include B&L Boston One Step Liquid Enzymatic Cleaner and Menicon Progent.
• Lubricants: Examples include AMO Blink Contacts, B&L Boston Rewetting Drops, and Menicon Rewetting Drops.
• Non-Preserved Saline: Examples include Medical Addipack Unit Dose, Menicon's Lacripure, and B&L Specialty Vision ScleralFil.

Preparation, Insertion, Re-centering, and Removal of Corneal GP Lenses

• Preparation: Work over a clean surface, wash and rinse hands, and inspect the CL for damage.
• Insertion: Stare straight ahead, retract the lower lid, and place the CL on the cornea. Release the inferior lid before the superior lid.
• Re-centering: Determine the CL location, look in the opposite direction, and gently manipulate the CL to the center of the cornea using the lids.
• Removal: Two methods: Lid Margin Technique and Canthus (Blink) Technique.

Evaluating Corneal GP CLs on the Eye

• BCR Selection: Initial choice depends on corneal curvature, including cylinder.
• Characteristics of Fitting Philosophies: Lid Attachment, Modified Lid Attachment, and Interpalpebral Fitting.
• Centration: CL should remain centered over the visual axis between blinks. Decentration is acceptable if the OZD covers the pupil and the edge doesn't put excessive pressure on the limbus.
• Movement: CL should have sufficient vertical movement for tear exchange, typically 1mm to 1.5mm.
• Assessment: Evaluate the fitting philosophy, centration, movement, and fluorescein patterns.

Impact of Design Changes and Troubleshooting for Non-Specialty Corneal GP CLs

• BCR: Modify in 0.10mm increments, steepen to tighten the fit, and flatten to loosen the fit.
• OAD: Modify in 0.5mm increments, increase to steepen the fit, and decrease to loosen the fit.### FINAL LENS Parameters
• FINAL LENS Parameters: -0.75DS / 7.65 BCR / 9.7 OAD

OZD (Ocular Zone Diameter)

• Increase or decrease in concert with OAD
• Flatten BCR by 0.05mm while increasing OZD by 0.5mm to maintain the same fitting relationship
• Dependent on pupil size, Refractive error, Corneal curvature, and Lid tension

PCR (Peripheral Curve Radius)

• Modify in 1.0 mm increments for testing purposes
• Ensures adequate tear pump for delivery of O2
• Aids in debris removal, eliminates bearing, and widens or flattens the peripheral curve radii to increase clearance and loosen the fit

Clinical Setting Example

• Flattening the peripheral curve radius: Increase the radius value to allow for more tear exchange
• Example: SCR 8.80 / PCR 10.80 → SCR 9.80 / PCR 11.80 (by increasing PCR by 1.0mm)

PCW (Peripheral Curve Width)

• Modify in 0.20 mm increments
• Flattening: Widen/increase width in mm
• Steepening: Reduce width in mm

Blend

• Default: "Medium" blend if not specified
• Functions: Remove debris, loosen fit, eliminate bearing, and enhance patient comfort

Edge

• Critical to patient comfort
• Modification based on power: (+) Lenticular (High minus >5.00D), (-) Lenticular (Low minus)