Medical imaging has come a long way since 1967, when Dr. McCoy of Star Trek could wave his tricorder over a patient and get complete diagnostic data, while the rest of us had little more than blurry X-rays. The ideal imaging device, according to Reference 1, should provide non-invasive visualization of internal structure with infinite detail and perfect contrast, in real time, at low cost. It should be easy for the doctor to use, with no more discomfort than the magic wand tricorder for the patient.
For eye examination, ultrasound technology is a leading contender in the quest for ideal. Here's the description of preparing the patient: “After topical anaesthesia, the probe was coupled to the eye using a scleral shell that held the eyelids open and filled with normal saline or the more viscous methycellulose for acoustic coupling.” I find this a bit disturbing, but more advanced ultrasound devices can be used, at least in some cases, with the eyelids closed.
Ultrasound imaging is valuable in the diagnosis of corneal diseases, glaucoma, cysts, and tumors. In addition, precise measurement of interior eye parameters is beneficial in planning for surgery to implant intraocular lenses, either in cataract treatment or for severe myopia.
There are many types of glaucoma, including plateau iris syndrome, pupillary block, malignant, and pigment dispersion. Ultrasound imaging is a useful tool for evaluation and planning treatment.
For corneal diseases, ultrasound imaging is used in the diagnosis of edema, keratoconus, corneal dystrophies, corneal scars, trauma, and keloid. Precise measurements of the cornea are also valuable in planning refractive surgery, including LASIK and similar procedures.
Both malignant tumors and non-malignant cysts and other growths can form in the eye. Ultrasound imaging can be valuable in diagnosis and treatment planning.
Ultrasound has been used for eye examination since the 1950's, but recent advances have greatly improved the image quality. The older systems used a frequency of 10 MHz. Current systems generally use 35 to 50 MHz, with some operating at 80 MHz. The high frequency technique is called ultrasound biomicroscopy, or UBM. Several equipment manufacturers offer photos of the images their devices can produce.
Sources:
Silverman RH, “High-resolution ultrasound imaging of the eye – a review”, Clin Experiment Ophthalmol. 2009 Jan; 37(1): 54-67.
Optikon HiScan:
http://www.optikon.com/en/hi-scan.asp
Sonomed VuMax:
http://www.sonomedinc.com/Ultrasound%20Biomicroscope.html
Quantel Medical Aviso:
http://www.quantel-medical.com/produit-echographe-aviso.php
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.