Posterior Corneal Elevation Measured by Pentacam rotating Scheimpflug

Posterior Corneal Elevation Measured by Pentacam rotating Scheimpflug Camera associated to Amsler-Krumeich Classification for Keratoconus. Henriquez Maria MD, Izquierdo Jr Luis MD, Bernilla César MD. Authors have no financial interest Instituto de Ojos OFTALMOSALUD Lima-Perú

PURPOSE The purpose of this study was to measure anterior and posterior corneal elevation values in patients with keratoconus diagnoses and to correlate these values with the Amsler. Krumeich classification for keratoconus.

METHODS This prospective study involved 103 eyes with keratoconus diagnoses between September 2006 until June 2008. INCLUSION CRITERIA: Keratoconus diagnoses by biomicroscopic and topographic signs. Keratoconus cases with a history of corneal surgery or with extensive corneal scarring were excluded. A single expert examiner, who was blind to the clinical condition of the patient, acquired Pentacam images using the Pentacam rotating Scheimpflug camera, software version 2. 0. Then the anterior and posterior elevation values were correlated with the Amsler Krumeich classification for keratoconus.

RESULTS STAGE OF MEAN ANTERIOR STANDAR MEAN STANDAR KERATOCONUS ELEVATION VALUE DESVIATION POSTERIOR DESVIATION ( um) ( DS ) ELEVATION VALUE ( DS ) I 7. 16 5. 36 11. 49 9. 05 II 15. 54 5. 71 24. 72 10. 41 III 22. 78 7. 03 32. 11 8. 08 IV 37. 50 26. 49 59. 90 37. 22 Mean anterior and posterior corneal elevation value was statistically higher in keratoconus stage IV (p=0. 00) compare with stage II and I.

STAGE I KERATOCONUS 81. 3 % 78. 9 % Mean: 11. 49 um Mean: 7, 16 um 41. 8% 39. 5% 30. 2% 25. 5% 13. 9% 23. 2% Corneal anterior elevation value (um) Corneal posterior elevation value (um)

EXAMPLE: Keratoconus Stage I [RX: -4, 00 -1, 00 25] 45. 85 D 8 um 7 um 8 um

STAGE II KERATOCONUS 48. 6 % ( 20 - 30 um) 79 % (6 -20 um) Promedio: 24. 72 um Promedio: 11. 49 um 25. 6 % 35. 5 % 25. 6 % 23 % 17. 9% 12. 8% Corneal anterior elevation value (um) Corneal posterior elevation value (um)

EXAMPLE: Keratoconus Stage II [Rx: -1. 00 -5. 00 10] 51. 84 D +25 um +38 um

STAGE III KERATOCONUS 77. 8 % ( 20 - 30 um) 66. 6 % (25 - 35 um) Promedio: 22. 78 um Promedio: 32. 11 um 55. 6% 33. 3% 22. 2% 11. 1% 20 -25 25 -30 30 -35 11. 1% 35 -40 Corneal anterior elevation value (um) 20 -25 25 -30 30 -35 35 -40 40 -45 Corneal posterior elevation value (um)

STAGE VI KERATOCONUS Promedio: 37. 5 um 40% Promedio: 59. 9 um 40% 20. 0% Corneal anterior elevation value (um) Corneal posterior elevation value (um)

EXAMPLE: Stage IV Keratoconus. 78. 49 D + 82 um + 132 um

CONCLUSION Posterior corneal elevation very effectively discriminates keratoconus stage VI from keratoconus stage II and I. Its efficacy is lower for discriminates keratoconus stage II and III and thus data concerning posterior elevation should be used to help us in stratify patients with this condition.