Posters

Pachymetry in high myopic patients: inter-device agreement of an ultrasound pachymeter, Pentacam, and Orbscan II before and after photorefractive keratectomy

Poster Details

First Author: N.Nassiri IRAN

Co Author(s):    K. Sheibani   N. Nassiri           

Abstract Details

Purpose:

To determine the agreement in central corneal thickness (CCT) measurement between ultrasound pachymetry, as the gold standard method, rotating Scheimpflug imaging (Pentacam, Oculus, Wetzlar, Germany), and scanning slit corneal topography (Orbscan II, Bausch & Lomb, Rochester, NY, USA) in high myopic patients before and after photorefractive keratectomy (PRK).

Setting:

Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Methods:

This prospective comparative study included 32 patients (61 eyes) with high myopia who underwent PRK. The 6-month postoperative CCT values were compared to their preoperative values in 27 patients (51 eyes) who completed the follow up. To find the level of agreement, Pentacam and Orbscan II readings were compared with the ultrasonic pachymetry readings as the gold standard method.

Results:

Mean CCT measurements with ultrasound, Pentacam, and Orbscan II were 557µm, 556µm, and 564µm, respectively, before PRK and 451µm, 447µm, and 438µm 6 months after surgery. Preoperatively, the 95% limits of agreement (LoA) with ultrasound were -20μm to 17μm for the Pentacam and -21μm to 33μm for the Orbscan II. Six months postoperatively, the 95% LoA were -30μm to 23μm for the Pentacam and -69μm to 43μm for the Orbscan II.

Conclusions:

Preoperatively, CCT measurements were higher with Orbscan II compared to ultrasound. Postoperatively, both Pentacam and Orbscan II measurements were lower than the ultrasound, but Pentacam had better agreement with ultrasound. The use of ultrasound as the gold standard method or Pentacam both appear to be preferable to Orbscan II among patients with high myopia. FINANCIAL INTEREST: NONE