course 9 corneal topography review and use in … · sco homecoming / fall ce weekend • october...
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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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• 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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