April 2009
Volume 50, Issue 13
ARVO Annual Meeting Abstract  |   April 2009
Comparison of Corneal Thickness Using Pentacam and Ultrasonic Pachymetry in Keratoconus and Ectasia Eyes
Author Affiliations & Notes
  • A. Prasad
    Ophthalmology, UMDNJ-New Jersey Med Sch, Jersey City, New Jersey
  • K. L. Fry
    Ophthalmology, Cornea & Laser Eye Institute, Teaneck, New Jersey
  • P. S. Hersh
    Ophthalmology, Cornea & Laser Eye Institute, Teaneck, New Jersey
  • Footnotes
    Commercial Relationships  A. Prasad, None; K.L. Fry, None; P.S. Hersh, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 3529. doi:
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      A. Prasad, K. L. Fry, P. S. Hersh; Comparison of Corneal Thickness Using Pentacam and Ultrasonic Pachymetry in Keratoconus and Ectasia Eyes. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3529.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : To determine the validity of Pentacam corneal thickness measurements to ultrasound pachymetry in a population of keratoconus (KC) and post-LASIK ectasia eyes.

Methods: : A retrospective review identified 78 eyes of 56 patients (50 KC eyes and 28 ectasia) that presented for consultation. There were 17 females and 39 males in this patient group. Corneal pachymetry was determined using Pentacam (Oculus Inc.) and ultrasound (Sonogage) methods. For ultrasound pachymetry, readings were taken at the thinnest location using the Pentacam map as a guide. Five readings were recorded using ultrasound and the smallest used for analysis. Corneal thicknesses were assessed for all eyes as well as separately for ectasia and KC eyes. In addition, KC eyes were evaluated by disease severity, as determined by the average of the Pentacam keratometry readings: mild (K<47D), moderate (47D<K<55D), and severe (K>55D).

Results: : For all 78 eyes and in each subgroup (KC and ectasia), Pentacam pachymetry readings indicated a high association to ultrasound pachymetry readings (r2=.90). Mean difference between measurements was 4.14 ± 17 µm for all eyes, with thinner ultrasound readings compared to Pentacam. In the ectasia and KC subgroups, ultrasound corneal thickness readings were thinner than Pentacam by a mean of 4.18 ± 17 µm and 4.12 ± 16 µm, respectively.There were 18, 20, and 12 eyes in the mild, moderate, and severe KC subgroups, respectively. For KC subgroups, there was good correlation between both modalities [mild: r2=.88; moderate: r2=.62; severe: r2=.71]. Mean differences were 6.11 ± 12 µm and 3.8 ± 20 µm thinner by ultrasound for mild and moderate disease groups, respectively. In contrast, in severe KC, Pentacam readings were slightly thinner than ultrasound by 0.17 ± 20 µm.

Keywords: keratoconus • cornea: stroma and keratocytes • cornea: basic science 

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