Specular microscope provides powerful magnification

A new automated microscope offers simplified photography and more accurate cell counts.

In part three in a series from the OSN Technology and Equipment Workshop featured at Hawaiian Eye 2010, John Vacca, vice president and director of the specular microscope division at Tomey USA, presented the Tomey EM 3000, one of the company’s latest innovations in corneal endothelium photography.

Improved light source, increased accuracy

The EM 3000 is a specular microscope that can be used daily to monitor and detect abnormal variation in cellular size and shape to ensure early diagnosis of endothelial disease.

Similar to an automated slit lamp, the EM 3000 uses an LED light source, which requires less maintenance than a conventional xenon lamp and is likely to last as long as the microscope itself. In addition, the LED light is easier on a patient’s eyes during the procedure, which involves shining light on the cornea to make the cells more visible.

“Everything in the cornea is transparent; otherwise you wouldn’t be able to get light through it,” Mr. Vacca said. “Now, when we shine a light at a 28° angle, what we’re really doing is causing shadows where the ends of the cells meet. And what we’re photographing is the difference between the light and the shadows, which form lines that create cells we can see.”

While a slit lamp can magnify cells only 30 times, the EM 3000 magnifies cells up to 190 times, capturing an area approximately 40% larger than that of Tomey’s competitors, Mr. Vacca said.

Eye care professionals can choose to count the cells manually, but the machine is equipped with a fully automated cell analysis system that counts the cells at the touch of a button.

“The EM 3000 can count up to 300 cells, depending on the patient’s cell count. And as far as we’re concerned, the more cells you count, the more accurate the count,” Mr. Vacca said.

The machine also offers the most accurate method of pachymetry, he added, because the front and back of the cornea are measured simultaneously, without having to move the optical assembly.

Guaranteed photographs

According to Mr. Vacca, the EM 3000’s color touch-screen technology makes photographing easier. Simply touching the center of the pupil displayed on the screen centers the image, and photos can be taken immediately with the auto-alignment and auto-shoot functions. The measuring head is also automatic, so the patient does not need to move in order for the fellow eye to be photographed. However, if a patient has an irregular cornea, the eye care professional can use a power joystick to focus on the endothelium.

With the EM 3000’s wide photographing range of 0.25 mm × 0.54 mm, eye care professionals can also take photographs at the center of the cornea and at six peripheral points, allowing them to select the photographing point with the best conditions.

Depending on the curvature of the cornea, the EM 3000 can take up to 15 photographs at a time, which virtually guarantees a successful photograph, Mr. Vacca said. Then, the best image among the shots is automatically selected and displayed on the screen. At the same time, the operator can view the other shots for possible disease.

Finally, a colored histogram provides a visual understanding of the corneal endothelium’s condition. The image can be displayed with the cell shapes traced and with certain areas and cell structures displayed in different colors, he said.

Compatible with EMRs

According to Mr. Vacca, everything needed to perform specular photography is built into the base of the EM 3000, except a database for storing data, images and patient information. However, he said Tomey offers a software package that is a mini electronic medical record (EMR) system designed to store endothelium photography. In addition, the machine has three outputs for EMRs, local area networks and a printer. — by Courtney Preston

• John Vacca can be reached at Tomey USA, 2630 E. Mohawk Lane, Suite 136, Phoenix, AZ 85050; 888-449-4045; fax: 602-508-4896; e-mail: jvacca@tomeyusa.com.