SCO HOMECOMING / FALL CE WEEKEND • OCTOBER 9-12, 2014

2014 FallCE@SCO

COURSE 9

Corneal Topography Review and Use in Fitting Contact Lenses

COPE Course 42491-CL

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•! Baseline examinations •! Screening/diagnosing pathology •! Surgical work-up and follow-up

–!Refractive Surgery –!Corneal Transplant

•! Monitor progression •! Enhanced fitting of RGPs

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“Standardized”(scales(keep(same(color/diopter(values(

across(maps((14!

“Normalized”(scales(tailor(the(color/diopter(values(to(

individual(maps((

A(“round”(paUern(means(very(liUle(

corneal(as5gma5sm(is(present.(

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An(“oval”(paUern(means(a(small(

amount(of(corneal(cyl.(

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Large(bow5e(means(larger(cyl((

and/or(limbusItoIlimbus(

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4(different(interpreta5ons(of(the(data(

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Curvature(Maps(measure…curvature!(

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Diopters( mm(

Axial(data(is(“smooth”(and(“averaged”.(

Axial(Map(assumes(center(of(curvature(

is(on(op5c(axis(

•  Smoothes(out(data((sphericalized)(

•  Best(for(picking(base(curves(

•  Cau5on(interpre5ng(“power”(in(periphery(

Tangen5al(data(has(more(precision(but(noisy(

Tangen5al(Map(measures(radius(from(

true(center(of(curvature((

•  PointIbyIpoint,(not(averaged(– Noisy(

•  Good(for(loca5ng(disease(

•  Cau5on(interpre5ng(“power”(in(periphery(24

Infero-nasal steepening OS>OD is evident on the axial map of a keratoconus patient. Tangential maps of the same patient show more detail about the size and location of the cone. Note that the dioptric values differ from the axial map.

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Refractive uses the local radius of curvature and ray tracing to measure the refraction and thus �true� power !

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Eleva5on(Map(

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•  Compares(to(closestIfiKng(sphere(–  Like(a(giant(CL(laid(over(top(

•  Shows(high(and(low(points(•  Useful(for((

– Disease(loca5on/extent(–  Predic5ng(NaFl(paUerns(

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Curvature(v.(Eleva5on(in(Keratoconus(

Normal(WTR(Cornea(Comparison(

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CL(FiKng(Guidelines(

•  1)(Try(for(10I20(microns(clearance(centrally(in(flat(meridian(–  Best(acuity!(

•  2)(Try(for(20I30(microns(clearance(along(whole(steep(meridian(

•  3)(These(are(for(~1.00DC(– Adjust(as(needed(

Topography(PaUerns(

•  Keratoconus(•  PMD(

•  PostIPKP(•  PostILASIK(•  PostIOK(

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Keratoconus(

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