Optivision, Inc.

The Leader in 3-Dimensional Corneal Mapping

Optivision EH-300 Fifth Generation Computerized Corneal Topographer

The Optivision CornealMap EH-300 is the result of 40 years of research and development. It is the descendant of the first fully automated Corneal Topography system. The Optivision CornealMap EH-300 introduced the following innovations to the field of Corneal Topography:
1) Auto-positioning/ auto-centration/ auto-focusing
2) Tangential/ Sagittal/ Gaussian/ refractive displays
3) Determined the X,Y,Z coordinates for each point on the cornea
4) 3-D display
5) Elevation maps (the first Z maps was shown at the AAO meeting in Las Vegas, 1987)
6) Simulated fluorescein contact lens fit
7) ASCII file (output data)
8) Side by side patient doctor (operator)
9) Keratoconus detection
10) Wavefront measurements of the cornea with Zernike polynomial
11) Fourier analysis with display of the harmonics
12) Summary plot showing the tangential, refractive, elevation and wavefront plots
13) Difference plots for dioptric, refractive and elevation
14) Innermost area measured .46mm, outer measurement 10mm plus
15) Microsoft Windows XP
16) Integrated e-mail system for transfer of data files

What is the Science behind today’s topography systems?

There are numerous corneal topography systems available today. One system, the CornealMap EH-300 Corneal Topography System, handles and displays data in a unique way, providing three levels of information. The CornealMap system provides corneal curvature in three ways, tangential (shape), sagittal (power) and Gaussian. Moreover, using the Z coordinates, the CornealMap can display the Wavefront of the cornea using the Zernike polynomial or the Fourier analysis to decompose the wavefront in separate harmonics.

The Optivision CornealMap measures the X,Y,Z coordinates of each points on the 23 rings and 360 meridian and up to 8280 locator points to map the cornea

The relationship between the cone, rings, optical axis, and camera of the CornealMap system is known by design and fixed in manufacturing. The CornealMap system locates the apex and the imaginary plane that touches the cornea at the apex. Scanning the digitized image will provide the x and y coordinates for any location. The distance between each point can be measured, and, since distance is due to curvature in the cornea, the Z coordinate for each point can be calculated. The 23 rings over 360 meridians give 8280 locator points on the corneal surface, providing greater coverage and sensitivity to the shape of the corneal surface.
By using the X,Y, and Z data, a 3D image is generated, demonstrating the changes in curvature across the surface of the cornea. This three-dimensional plot is an excellent tool to educate patients. It makes it easier for them to understand the image without having to know what the colors mean. The most popular display is the dioptric plot, a view of corneal curvature in terms of power, orientation and astigmatism.

Automatic Centering, Focusing, and Capturing

The CornealMap EH-300 system, now in its fifth generation, was the first system to automate centering, focusing, and capturing, a most helpful feature. The CornealMap can now capture up to five consecutive pictures. When different operators are introduced to the equation of patient image capture, some assistants bias the focus to their preference. This automated function assists in eliminating operator bias, which is imperative for accurately capturing the data. The feature speeds up exams and ensures compatibility among operators. For difficult patients, however, the CornealMap system incorporates a manual image-capture override to allow the operator to capture an image manually.
Once the image or images has been captured and locked into the digital memory, the operator can now examine the quality of the mires using the analysis to ensure that data collected are good. The operator can excludes at will the out of focus image and keep the rest for measurement. An average plot along with the other plots is displayed.

Sensitivity is key, especially in PRK

The inner ring of the CornealMap EH-300 system is .46mm diameter, and the outer ring is 10 mm, allowing for a great sensitivity of the central corneal surface. This feature is presently important but even more useful now with excimer refractive surgery. Following refractive surgery, some of the visually significant corneal irregularities are very subtle and easily missed. Central islands are residual, steepening in the center of the refractive surgery ablation. Competitive systems may miss these islands and only show a smooth central surface. Diagnosis of such irregularities will be paramount in postoperative care of Lasik/Lasek/PRK surgery patients.

Analyze images in 10- and 1- degree steps

The Optivision CornealMap EH-300 system also has the capability of analyzing an image in 10- and 1-degree steps. The 10-degree detection variation offers sufficient analysis of normal corneal surfaces. When the subtle details of incision sites, transplant margins, or contact lens warpage are needed, the 1- degree detection will provide the most data and coverage. When small epithelial irregularities cause overlying tear film breakup that can affect results, the 10-degree mode eliminates erroneous data from the map.

Data Verification

One of the many special features of the CornealMap EH-300 system is the Verify window. The Verify window provides a guide to accurate analysis of the data. The function eliminates technician subjectivity, because it verifies the accuracy of the image captured and determines whether the data are dependable and true. The competitive systems require close scrutiny of the data points on the image to determine whether the data are useful, encouraging operator subjectivity. Without the CornealMap EH-300 Verify window, other systems allow analysis of data that should have been discarded and recaptured.


Notice on the image above that the computer has missed some data points in the center of the image, yet it is very hard to detect by casual observation.


The next screen (on the right) demonstrates a verification screen that clearly shows the data collected have missing data points and should be retaken.


Having the operator look at each individual dot on the screen to verify accuracy in detection is a tedious and difficult task, and it does not ensure that bad data will be detected. The next screen demonstrates the data (insert image) collected are continuous and complete. It is important to understand there is no guarantee that the analysis is correct if the system does not demonstrate the accuracy of the detection of the data points.


The image above demonstrates the dioptric plot that has missing data points. Observe the “blue flame” originating from the center of the plot. This indicates that a data point or group of data points was missed.

Why is networking/co-management important?

An important consideration for eye doctors is the ability to participate in the new explosion of Surgical Keratorefractive referral and co-management organizations. Ophthalmologists and optometrists alike will be interested in a corneal topography system that has the capability of sending patient data, images, and graphs to another offsite doctor or center: The CornealMap EH-300 system has software capable of achieving this.

Send data anywhere

The receiver of the patient files will be able to view or manipulate and alter the data using CornealMap system or CornealMap EH-300 Executive Software. A single CornealMap EH-300 or multiple CornealMap EH-300 systems are connected to a local area network (LAN) and Internet E-mail service provider. Remote locations on the LAN and those with a sending/receiving E-mail address can store and retrieve patient files.

The method for sending the data to remote sites uses any Windows-compatible E-mail client. The Windows software facilitates system operation and patient file management. This will expedite as well as improve patient co-management among doctors at different sites. It will be helpful with expediting second opinions and advising doctors’ responses.

Advanced design

The design of the CornealMap EH-300 system enables the operator to position the patient for the optimum use of office space. The components can be arranged side by side, allowing the assistant to directly visualize head position and assist, or if necessary, face to face 90 degrees, providing flexibility and patient comfort. The feature is convenient for operator and patient. The system is even designed to comfortably accommodate patients using wheelchairs.

Is there technology that can help in difficult-to-evaluate cases?

The CornealMap EH-300 technology provides the flexibility to evaluate difficult corneal cases that fall outside of the standard range. Because the Optivision CornealMap Topography system has good corneal coverage and a wide range of adjustable parameters, almost any irregular corneal surface can be imaged and analyzed.