KC Presentation 1

8/8/2019 KC Presentation 1

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Marc L. Braithwaite, OD

Vision Care of Maine



Keratoconus

What have the years taught us?



Keratoconus Characteristics

Non-inflammatory.

Central or para-central corneal thinning.

Corneal steepening or protrusion.

Increased astigmatism and possiblymyopia.

Loss of best spectacle corrected visual

acuity. Corneal striae and scarring.

Corneal hydrops (inflammatory).



Causes of Keratoconus

Heredity vs. Mechanical

Cellular

Tissue

Genetic



Heredity vs. Mechanical

Does eye rubbing cause Keratoconus?

2 out of 250 doctors feel that rubbing is

a cause. KC patients do rub their eyes more often

than those without KC.

What is it that makes KC patients rub

their eyes?



Cellular Changes

Keratoconus cells are hypersensative.

Increased enzyme activity, lack of

enzyme inhibitors. Matrix substrate instability in response

to environmental stress factors.

mtDN A damage and exaggerated

oxidative response causing cellular damage.



Tissue Changes

Loss of Bowman¶s layer.

Lamellar slippage.

Lack ³anchoring´ lamellar fibrils.

Apoptosis of the stroma causing anterior

thinning.



Genetics

Autosomal dominant w/variable

penetrance.

SOD1, an antioxidant enzyme, is

abnormal in some KC corneas.

No single gene responsible.

10 different chromosomes have been

associated with KC.

Most likely multiple genes involved.



Progression and Prognosis

Age is a big factor.

The younger the diagnosis, the poorer the prognosis.

Less likely to progress to the point of atransplant if diagnosed in the 30¶s.

20% of Keratoconus patients result in

corneal transplants. 35 to 45% of all transplants are due to

Keratoconus.



Possible Aggravating Factors

UV exposure.

Allergies.

Vigorous eye rubbing.

Poorly fitting contact lenses.

Inflammation.



Types of Keratoconus

Nipple/Oval cone - central or mildly

para-central localized thinning and

steepening.

Keratoglobus - Large generalized

thinning and steepening.

PMD (pellucid marginal degeneration) ±

peripheral thinning and steepening. Keratoconus Fruste ± Less progressive

and less manipulative.



Nipple/Oval Cone

Central Steepening

Steepest form



Keratoglobus

Wider ± 75 to 90% of cornea.

Not as steep.



Pellucid Marginal Degeneration

Peripheral Thinning



How to Treat Keratoconus

Spectacles

Contactsy Soft Standard

y

Soft Customy RGP Standard

y RGP Custom

y Hybrid

Surgery

y Intacsy Penetrating Keratoplasty

Riboflavin/UV treatment



When to Intervene?

Best Spectacle/Soft CL Acuity 20/30 or

better?

y Good tolerance of acuity.

y Corneal health is not compromised.

y ³If it aint broke, don¶t fix it.´

Best Spectacle/Soft CL Acuity worse

than 20/30?y Specialized contact lenses.

y My opinion, use RGP lenses.



Which RGP Design?

Early Keratoconus

y Standard RGP

y KC RGP

Mid-stage Keratoconus

y KC RGP

y Custom KC RGP

Advanced Keratoconusy Custom KC RGP

y Intra-limbal or Scleral RGP



My ´GO TOµ Lens ² Rose K

Developed by Dr. Paul Rose.

Designed to fit the irregular cornea.

³Very forgiving lens´ Multiple designs to fit all shapes of

corneas and corneal conditions.

Blanchard is very good to work with and

has staff to assist with very difficult

cases.



Nipple/Oval Cone Fitting

Most common form of KC.

Early stages - simple RGP or KC RGP

Later stages ± KC RGP usually smalland steep.

The steeper the cone, the smaller the

lens diameter.



Rose K2

Rose K vs. Rose K2

72% of patients notice an increase in

acuity with aspheric, aberration control.

Lens to be centered on the cone.

Reduce excessive movement (1 to

2mm).



Fitting the Rose K2

Too high ± tighten edge lift

reduce OAD

steepen base curve

Too low ± increase edge lift

increase OADflatten base curve



Fitting the Rose K2

Centrally fitting the

lens on a nipple

cone better insuresoptimal acuity and

comfort.



Rose K2IC

IC stands for irregular cornea

Larger diameter

Larger optic zone Aspheric for aberration control

Reverse geometry design



PMD

Keratoglobus

LASIK induced ectasia

Corneal transplants



Corneal Dystrophies

Traumatic Corneas with Scars

Post RK

Irregular Astigmatism or CornealWarpage



What is That?



Asymmetric Corneal Technology

ACT.



ACT ² Continued«



Using ACT ( Asymmetric Corneal Technology)

3 standard grades available

Option also to specify degree of tuck in 0.1 steps from 0.4 to 1.5mm

Grade 1 ( 0.7mm steeper)

Grade 2 (1.0mm steeper)

Grade 3 (1.3mm steeper)

Fitting with ACT



NO ACT WITH ACT

ACT - Improved comfort , lens stability and vision

Fitting with ACT



Toric Peripheral Curves



Fitting Pearls

Tendency to tighten after initial fitting.

Light central touch will increase acuity.

Avoid central staining.

Movement is necessary but slightmovement is usually sufficient.

Pay attention to tear flow beneath lens.

The steeper the lens, the smaller OAD and

less movement.

Don¶t change too many parameters atonce.



Penetrating KeratoplastyWhen to refer?

Acuity is 20/50 or worse.

Patient intolerance to visual decrease.

Scars within the visual axis. Multiple episodes of Hydrops.

Contact lens intolerance.

Unable to get adequate/healthy CL fit.

Consider OD to OD referral.

Give reasonable expectations.



Post PKP Management

How soon can you fit with lens?

Why are the curvatures so strange?

Do you have to wait for all sutures to beremoved?

Corrective options.

y Spectacles

y RGP contact lenses.

y LASIK



Rose K2 Post Graft



PKP Topography



Rose K2 Post Graft

Much more difficult to fit than KC.

Patients are less tolerable to CL.

Eyes are more dry.

Ill-fitting contact lenses can lead to graft

rejection.

Lens design is crucial to success.



K2PG Fitting Pearls

Don¶t be intimidated!

Watch tear flow!

Also good lens for ectasia patients. Stay with your fitting basics

y Fit base curves.

y Adjust diameter.

y Adjust peripheral curves.

y Use ACT or Toric PC if needed.



Post Graft ² Too Steep



Post Graft ² Too Flat



Post Graft ² Good Fit



Watch Vasculature



What Do You Do?



Mini-Scleral Design - MSD

Large RGP

Vaults the cornea, rests on the sclera.

Creates a fluid filled environment.

Can be used to treat any corneal

condition.

Can be used to treat other anterior

segment conditions.



MSD - Advantages

Very Stable lens.

Fluid filled environment.

Improved comfort.

Good visual acuity.



Mini-Scleral Design



MSD ² Fitting Pearls

Central Feather-touch.

Intra-limbal adjustment.

With or without

fenestration or

fenestrations.

Watch edge for

tightening.



Practice Management Issues

Setting Fees.

Bill for services performed.

Insurances and fee collection.

Appropriate diagnostic and treatment

equipment.

y Topography/corneal mapping.

y Pachymetry.

y Fitting sets.



Refractive Surgery Specific

Moderate ± Large Diameter

y (10.5 mm Standard Diameter, 9.5 mm to

12.0 mm).

Reverse Geometry Transition.

Post Surgical Central BC.

Curves

Paracentral Fitting Curves.

Asymmetric Corneal Technology (ACT).



Thank You!

KC Presentation 1

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