We tend to take three dimensional vision for granted and under look the importance it plays in our daily lives: from driving, to picking up a pencil and cooking to stepping off a curb. It requires the collective efforts of both of our eyes and our brains in order to judge depth, width and height of objects.
In the world of ophthalmology, not only do we strive to restore and maintain a patient's three-dimensional vision, but also advances in technology have allowed us to measure depth and distance through the use of a variety of instruments in order to visualize how disease processes affect the eye.
Spectral domain optical coherence tomography (SDOCT) allows high-speed imaging of many eye conditions using infrared light. SDOCT uses voxels to create 3-D images, allowing the physician to change the viewing angle of the optic nerve, cornea, lens or other parts of the eye.
Topcon makes the 3D OCT-2000. This system incorporates a high-resolution fundus camera and a color touch screen display. It has a FastMap™ software that enables 3D, 2D and fundus image viewing simultaneously. Pin-Point™ Registration shows the location of the OCT image within the fundus image. This unit has a compare function that allows viewing of serial exams in a comparison view with use of different analytical tools.
Carl Zeiss makes the Cirrus HD-OCT, another 3D system using direct data cubes. Users can 'Fly Through the Cube' in order to view all B-Scans in just seconds. The change analysis functions provide measurements from 2 separate visits and provide a thickness change map for the macula or nerve fiber layer. The data cubes are automatically registered to cubes from prior visits and aligned to allow pixel-by-pixel comparisons to the prior visit. There is a Macular Thickness Normative Database allowing comparison of the patient's macula to a database of known normal subjects.
Optovue makes the RTVue-100, an ultra-high speed, high resolution OCT based on Fourier-Domain Optical Coherence technology. This unit also comes with thickness mapping of the retina and nerve fiber layer. It has a Macular Normative Database and change analysis as well as 3D viewing of the macula, optic disc and cornea.
There are many 3D systems on the market not mentioned in this article. When considering an SD-OCT purchase, ask whether the unit has legacy support. Will it support data acquisition from your old system? The Cirrus HD-OCT comes with reader software whereas others you have to purchase separate software. Topcon has actually built the reader software into their units.
Advances in ultrasound biomicroscopy (UBM) also allow 3-D imaging of the crystalline lens. Dr. Jean-Marie Parel at the Bascom Palmer Eye Institute developed a novel UBM scanning system providing a 3-D set of data for a computer display.
Operating microscopes made for ophthalmology must also provide excellent 3D capability for surgical ease. Leica Microsystems manufactures several, among them are those listed below.
The Leica M220 F12 is a new microscope tailored for the ophthalmologist to include a motorized 5-step APO-chromatic magnification changer and focus
allowing hands-free adjustments, LED illumination without fiberoptic cables, and an upgradeable XY unit, all of which are standard features. The microscope is compact and has a long arm for ease of positioning.
The Leica M844 F40 comes with the APO OptiChrome system that provides excellent image quality with higher contrast and resolution for more detail of the tissues. This microscope also has the Leica OttoFlex II, an integrated, independent illumination system that provides a red reflex even in low light conditions. Leica QuadZoom technology gives 100% illumination, stereopsis and the same magnification for both the surgeon and the assistant. Finally, the unit has a real time video monitor, operated by a touch screen.
As well as technological advances, there are companies dedicated to restoring vision to patients. TruVision is one such company, founded in 1996 and located in St. Louis, Missouri. TruVision is a third-party administrator of vision services that collaborates with health plans and large corporations to offer laser vision correction and contact lenses at significant discounts to over 100 million members. This company contracts with chains, independent doctors and manufacturers.
Surgically, 3D vision is paramount, but an extra bonus is when you can record the case. Optronics offers a Microcast 3 CCD RGB high-resolution microscope camera that is simple to operate and easy to install on any surgical microscope with a C-mount adapter. It provides real-time, 36-bit RGB image processing. This system is ideal for broadcasting and recording. The material can be edited, published and downloaded directly to a computer. Optronics also manufactures a line of Quintus microsurgical video adapters for use with surgical microscopes. They range from 45mm to 80mm.
Again, the world of 3D has become an area of increasing interest amongst innovators across the board. In ophthalmology, the possibilities are endless and scientists continue to strive in advancement of technology to improve our field day by day.