General Problem-Solving
Use the tips on this page and on page 10 to solve your GP fitting problems.
Flexure
Symptoms
- Vision varies with blink or poor initial vision
Causes
- High astigmatism
- Steep BCR
- Thin design
- Large OZD
Diagnosis
- Toricity with over-keratometry but spherical on radiuscope
Management
- Flatter BCR
- Increase CT
- Reduce OZD
- Switch to lower Dk material
Decentration

Inferior Decentration


Superior Decentration
Lateral Decentration
Symptoms
- Vision varies with blink
- Lens awareness
Causes
- Decentered corneal apex or ATR astigmatism
- Tight or loose lid tension
- Thick lens design
- High specific gravity material
- Unusual corneal topography. (Beware of superior flattening and inferior steepening shown in topography for long-term wear of superior positioning GP.)
Diagnosis
- Biomicroscopic evaluation during and after blink: see excessive movement with blink or simply stays in a decentered position. Patient views through non-optical periphery of lens, often intermittently.
Management
Inferior Decentration
- (+) lenticulate if power >-5.00
- (-) lenticulate if power <-1.50
- (-) lenticulate all + lens
- Bitoric for >2.50 cylinder
- Lid attachment design
- Flatter BCR
- Minimize CT
- Lower specific gravity material
Superior Decentration
- Plus lenticular
- Increase CT
- Steepen BCR
Lateral Decentration
- Larger overall diameter
- Steeper BCR
- Aspheric design
Corneal Dessication 3 & 9 Staining


Symptoms
- Lens awareness
- Occurs in more than 50% of rigid lens wearers
Causes
- Dryness
- Lid margin disease (meibomianitis) and blepharitis can compromise tear film
Diagnosis
- Phenol Red Thread
- 3 and 9 o’clock punctate staining
- Severity range from diffuse punctate staining to corneal opacification and neovascularization
Management
- If staining coalesced, improve centration
- Decrease edge lift (consider aspheric design or steepen PCR & PCW)
- Change to F-S/A material
- Ensure proper blinking & frequency
- Frequent use of rewetting drops
- Lid hygiene
- Hot compresses with gentle lid massage for meibomian gland dysfunction
- Humidifier
– OR –