OCULUS Pentacam Interpretation Guide

8
3.3 Refractive power map
This map (Figure 3) uses only values from the anterior surface, but it also takes effect “A” (see above)
into account. It calculates corneal power according to Snell’s law of refraction assuming a refractive
index of 1.3375 to convert curvature into refractive power (Figure 2). This is a map that other
Placido topographers also may show because it only considers the anterior surface.
Figure 2: Snell´s law of refraction
Figure 3: Refractive power map of a sphere, r = 8 mm
3 Differences between the various topography maps of Pentacam
®

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