Tomography is an innovative technique to display a representation of a cross section through a human body or other solid objects using x-rays or ultrasounds. Tomography brings together technology, biology, and mathematics to solve problems in many areas. A specific type of tomography is optical tomography. Optical tomography is a form of computed tomography that creates a digital volumetric model of an object by reconstructing images made from light transmitted and scattered through an object. It’s mostly used in biomedical imaging research today. The purpose of an optical tomography is for the ophthalmologist, a osteopathic doctor who specializes in eye and vision, to be able to study each of their patient’s retina’s distinctive layers in the eye. The retina is a light sensitive layer at the back of the eye that covers about 65% of its interior surface. During an optical coherence tomography exam, an ophthalmologist may put dilating eye drops in your eyes. The drops will widen the patient’s pupil to make it easier to examine their eye’s retina. The patient will then sit in front of the OCT machine and rest their head on a support to keep it motionless because if they move, it will affect the examination. The machine will then scan your eye without touching it. The scanning portion will take about 5 to 10 minutes. If their eyes were dilated, they may be sensitive to light for several hours after the OCT exam (“What Is Optical Coherence Tomography?”). The mechanisms of OCT are similar to that of an ultrasound, only instead of sound waves OCT uses the reflection of light. Optical Coherence Tomography is often used to evaluate disorders of the optic nerve. The exam helps your ophthalmologist detect changes to the fibers of the optic nerve. For example, it can detect changes caused by glaucoma. This type of tomography is useful in diagnosing many eye conditions like: macular hole, macular pucker, macular edema, age-related macular degeneration, central serous retinopathy, diabetic retinopathy and vitreous traction.The mathematical portion of optical tomography can be very intensive. The inverse problem of optical tomography is to reconstruct the optical properties of a medium of interest from boundary measurements (Scotland, 2011). Mathematical equations can range from the Maxwell equations at the microscale, to the radiative transport equation at the mesoscale, and to di?usion theory at the macroscale. Typically, to solve an inverse problem is by nonlinear optimization. Nonlinear optimization is the process of solving a problem defined by a system of equalities and inequalities, where some of the constraints or the objective function are nonlinear. Maxwell equations are appropriate for microscale or “forward problems” because the mathematical description of light propagation in random media changes according to the length scale of interest (Scotland, 2011). Radiative transport is relevant at the mesoscale because of the way the light passes through a material medium is formulated in terms of a conservation law that accounts for gains and losses of photons due to scattering and absorption (Scotland, 2011). At the microscale, the diffusion theory works best because of the high-frequency asymptotics, the approaching of a value or curve, of wave propagation in a random medium.An example of the mathematical part of optical tomography is an analytical optical coherence tomography model based on the extended Huygens-Fresnel principle: . When an optical wave goes through an object like a tissue, both the amplitude and phase of the electric field experience random fluctuations caused by small random changes in the index of refraction. R denotes a point in space, k is the wave number of the electromagnetic wave, and n(R) is the index of refraction whose time variation has been suppressed. There are many technicals and uses of optical tomography. The most frequently used ones are diffuse optical tomography (DOT) and optical coherence tomography (OCT). Diffuse optical tomography is a method of imaging using near-infrared spectroscopy (NIRS), the study of the interaction between matter and electromagnetic radiation, or fluorescence-based methods. This technique probes absorption as well as scattering properties of biological tissues (Hielscher). It also doesn’t use radiation. The main applications of DOT are the brain, breast, limb, joint, etc. DOT is very convenient at times when an MRI can’t be used, such as pacemakers or screws, and for bedside monitoring. DOT technology could be used to monitor developmental disorders, like autism, and neurodegenerative disorders, such as Parkinson’s. Optical coherence tomography (OCT) is a medical imaging technique in which it uses light to take 3D images of biological tissues. OCT is known for finding and diagnosing people with eye conditions such as: macular edema, age-related macular eye degeneration, glaucoma, etc (Fujimoto, 2000). OCT can also be used to create images inside your blood vessels using near-infrared light (Su, 2016). Because this is fairly new, there are clinical trials being done and research being conducted to see how effective it is in diagnosing diseases in patients and breakthroughs in medicine. Imaging the back of the eye presents unique challenges. The human pupil limits the aperture of the eye, and avoiding glare from reflections from the cornea and crystalline lens presents a significant challenge. A german physician and physicist named Hermann Ludwig Ferdinand von Helmholtz is generally credited with the invention of the first ophthalmoscope in 1850, permitting observation of the retina, and fundus cameras recording images on film. The first commercial instrument , OCT 1, was launched in 1996. This instrument gave researchers around the world, the opportunity to investigate clinical applications of OCT. By today’s standards, the performance of OCT 1 is modest and there was a big learning curve for interpreting images of retinal pathology. With every generation of OCT, the advancement is everytime more and more expensive. Commercially available systems are priced beyond the reach of most users. On resale sites like eBay, a used Stratus ophthalmic OCT systems are around $35,000, but they’re not FDA approved. Meaning clinical are not allowed to use them unless they are FDA approved. Systems that are approved by the FDA typically cost about $70,000. A cost analysis performed by the Veterens Affairs Health Care System in Boston determined that the cost of its OCT machine was recovered after four months of use. The analysis compare the annual cost of using only fluorescein angiogram (FA) for the diagnosis of macular disease with the annual cost of using both FA and OCT. THe study found that in the year before the OCT system was purchased, 411 FAs were performed at a cost of $297,498 , an average of about $724 per test. The year after the OCT system was purchased, 692 diagnostic procedures were performed with a total cost of $325,695, an average of about $471 per test. Out of the 692 diagnostic procedures , there was 336 FAs at $243, 210 and 356 OCTs at $82, 485. Meaning performing an OCT exam only costs about $232 per test. But as always, everyone wants more. More speed, better resolution and higher regristration are being developed to enable the systems to take images quickly while tracking eye movements and avoiding blink response. New software is being created to enable OCT users to analyze greater amounts of data and to compare it to normative data. Tomography was first used around the 1930s but it wasn’t as effective as it is now. With the technological advances in medicine rising, there are many forms and uses of tomography. More precise and infinite high resolution OCT scans may be able to diagnose systematic diseases much earlier, with high sensitivity and specificity through ocular magnification. Innovations are in progress to include OCT in evaluating inflammatory , traumatic and degenerative ocular and systematic lesions, not only for ophthalmologists but for a spectrum of clinicians. Overall, the use of tomography is safe to both the patient and doctor. CT scans, computerized tomography, are known for diagnosing broken bones, blood clots, cancer, etc. Without CT scans, or tomography in general, it would be extremely difficult to solving the world’s biggest medical problems today.