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Evaluation of Long-Term Keratoconus Progression Using Scanning-Slit TopographyFirst Author: David Galarreta, MDContributing Authors: Nestor Cortes, MD, Fernando Sanchez-Mannarelli, MD, Alejandro Portero, MD, Belen Carrasco, MD, Jesus Merayo-Lloves, MDHospital Clinico Universitario Valladolid (Spain)IOBA. Universidad de Valladolid (Spain) The authors have no financial interest in the subject matter of this poster VI World Cornea Congress, Boston 7-9th April 2010
Purpose • To evaluate the long term changes and predictor factors of evolution in keratoconus using corneal elevation topography parameters measured by scanning-slit topography system
Methods • Retrospective study • Ninety three eyes from 52 keratoconic patients were evaluated by scanning-slit topography system. • Diagnosed by slit lamp findings and by corneal topography • Minimum follow up of 3 years was required with topography examinations at least twice. • Tenets of the Declaration of Helsinki were followed and local medical ethics comitee approved the study.
Methods • Age at onset and at analysis • Sex • Quantitative topographic parameters analyzed • Keratoconus topographical pattern • Minimum mean simulated keratometry (minSimK) • Maximum mean simulated keratometry (maxSimK) • Maximum keratometry reading (Kmax) • Posterior and anterior best-fit sphere (BFS) • Posterior/Anterior BFS ratio (P/A BFS) • Thinnest and central pachymetry point
Results • Age • 26,46 years 9,51 (SD) at onset (diagnosis). • 39,12 years 10,4 (SD) at analysis. • Sex: 53,84% male • Follow up: 3,91 y1,94 (SD).
Results • Whole keratoconus group (n=93) • MaxSimK: 49,63D to 50,40D (p=0,006) • MinSimK: 44,94D to 45,94D (p<0,001) • ABT/SRAX pattern group (n=24) • Posterior BFS: 54,06D to 54,62D (p=0,042) • MaxSimK:48,55D to 49,47D (p=0,01) • MinSimK: 43,67 to 45D (p=0,01) • Kmax: 51,66D to 52,46D (p=0,03) • Inferior steeping pattern group (n=33) • Anterior BFS: 43,87D to 44,42D (p=0,004) • Posterior BFS: 54,59D to 55,41D (p=0,006) • MinSimK: 45,12D to 46,14D (p=0,017) • Kmax: 53,24D to 54,99D (p=0,006) • No changes detected in other patterns (low n bias)
Results • Age at onset (percentile 50th= 31,26 years) • Younger patients (<31,26 years) • MaxSimK: 50,05D to 51,23D (p=0,022) • MinSimK: 44,83D to 46,48D (p<0,001) • Posterior BFS: 54,86D to 55,70D (p=0,002) • Kmax: 53,52D to 55,45D (p<0,001) • No changes detected in older patients (p>0,05)
Results • Kmax groups • <47D • MaxSimK: 45,16D to 46,35D (p=0,04) • 47D-50D • Posterior BFS: 54,23D to 55,01D (p=0,011) • MinSimK: 43,78D to 44,78D (p=0,028) • 50D-53D • MaxSimK: 51,15D to 52,22D (p=0,025) • MinSimK: 46 to 47,56D (p=0,012) • >53D: Showed no pregression • Nor difference in age at onset nor at follow up
Results • Thinnest pachymetry (p50th=432 microns) • Thinner pachymetry (<432 microns) • MaxSimK: 51,37D to 52,06D (p=0,02) • MinSimK: 46,6D to 47,9D (p<0,001) • Thicker pachymetry (>433 microns) • Anterior BFS: 43,4D to 43,87D (p<0,001) • Posterior BFS: 52,82D to 53,66D (p<0,001) • Central pachymetry: 501 microns to 493 microns (p=0,016) • Thinnest pachymetry: 480,6 microns to 470,7 microns (p=0,019) • MaxSimK 47,88D to 48,78D (p=0,021)
Results • Posterior BFS (p50th=54,5D) • <54,5D • Posterior BFS: 52,22D to 52,74D (p=0,013) • Central Pachymetry: 481 microns to 476 microns (p=0,04) • MaxSimK: 46,9D to 47,83D (p=0,027) • MinSimK: 43D to 43,69D (p=0,038) • >54,5D • MinSimK 46,96D to 48,28D (p<0,001)
Results • Posterior/Anterior BFS (p50th=1,24) • <1,24 • Posterior BFS: 52,89D to 53,37D (p=0,002) • Central Pachymetry: 481 microns to 473 microns (p=0,022) • Thinnest pachymetry: 460 microns to 451 microns (p=0,021) • MaxSimK: 48D to 48,8D (p=0,04) • Posterior/anterior BFS: 1,20 to 1,21 (p=0,03) • >1,24 • MinSimK 46,1D to 47,39D (p<0,001)
Conclusions • Younger age at onset increased the probability of progression of topographical parameters in keratoconus. • Topographical patterns of keratoconus (Asymmetric bow tie with skewed radial axis and inferior steepeninig) provide information about a higher risk of progression. • Very high K readings, thinner corneas, high power in posterior BFS,and high posterior/anterior BFS showed less progression of keratoconus topographical parameters. These variables normally correlates with an advanced keratoconus. • Low K readings, thicker corneas, low power in posterior BFS, and low posterior/anterior BFS can potentially showed a wide margin for advance in keratoconus