OCULUS Pentacam Interpretation Guide

119
16 INTACS
®
implantation
16.2 Case 2: INTACS
®
after PRK
by Alain-Nicolas Gilg, MD
A 45-year-old female had had photorefractive keratectomy (PRK) in both eyes 7 years earlier.
Before the laser surgery her visual acuity had been
 OD: sph -7.50 cyl -0.50 A 170°
 OS: sph -6.75 cyl -1.00 A 10°
She was referred for blurred vision, photophobia, and poor intermediate VA. Zernike analysis
confirmed the functional disorders of her vision, showing them to be due to abnormal spherical and
high order aberrations (HOA), |Z|4° (spherical), |Z|5³ (trefoil 5
th
order) |Z|6² (astigmatism 6
th
order)
(Figure 147).
The keratoconus menu of the Pentacam® identifies this cornea as an oblate postoperative cornea.
Note the negative eccentricity and the abnormally high aberration coefficient due to the HOA
(Figure 148).
The pachymetry map shows a smooth progression with a thick area for the implantation of the
INTACS® in the 7 mm zone. This made her a good candidate for INTACS® implantation.
Before the implantation of corneal INTACS® her visual acuity was:
 OD: sph -1.25, cyl -0.50 A 175° VA 20/25
 OS: sph -1.50, cyl -0.50 A 55° VA 20/40
Figure 147: Zernike Analysis topography pre INTACS
®

OCULUS Pentacam Specifications

General

Measurement Time	Less than 2 seconds
Corneal Coverage	Up to 12 mm
Software	Pentacam Software
Data Transfer	USB
Corneal Topography	Yes
Display	External monitor required
Measurement Principle	Scheimpflug imaging
Camera	Rotating Scheimpflug camera
Light Source	Blue LED
Pachymetry	Yes
Anterior Chamber Analysis	Yes
Imaging Principle	Scheimpflug imaging
Fixation	Internal
Power Supply	100-240 V, 50/60 Hz
Resolution	High resolution
Lens Density Measurement	Yes
Dimensions	Varies depending on model and configuration
Weight	Varies by model, check manufacturer specifications
Number of Images	25 or 50