Optical Microscopy and Endoscopy

- Optical Microscopy

The optical microscope, often referred to as the “light optical microscope,” is a type of microscope that uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly designed in their present compound form in the 17th century. Basic optical microscopes can be very simple, although there are many complex designs that aim to improve resolution and sample contrast. 

The object is placed on a stage and may be directly viewed through one or two eyepieces on the microscope. In high-power microscopes, both eyepieces typically show the same image, but with a stereo microscope, slightly different images are used to create a 3-D effect. A camera is typically used to capture the image (micrograph). 

The sample can be lit in a variety of ways. Transparent objects can be lit from below and solid objects can be lit with light coming through (bright field) or around (dark field) the objective lens. Polarised light may be used to determine crystal orientation of metallic objects. Phase-contrast imaging can be used to increase image contrast by highlighting small details of differing refractive index.

Optical microscopes have a ubiquitous presence in modern society. Recent research is advancing the field of optical microscopy, giving the field a critical new tool to solve challenging problems across many fields of science and engineering including semiconductor wafer inspection, nanoparticle sensing, material characterization, biosensing, virus counting, and microfluidic monitoring.

- Endoscopy

Endoscopy is the insertion of a long, thin tube directly into the body to observe an internal organ or tissue in detail. It can also be used to carry out other tasks including imaging and minor surgery. Endoscopes are minimally invasive and can be inserted into the openings of the body such as the mouth or anus. 

Endoscopy is a nonsurgical procedure used to examine a person's digestive tract. Using an endoscope, a flexible tube with a light and camera attached to it, your doctor can view pictures of your digestive tract on a color TV monitor. 

During an upper endoscopy, an endoscope is easily passed through the mouth and throat and into the esophagus, allowing the doctor to view the esophagus, stomach, and upper part of the small intestine. 

Alternatively, they can be inserted into small incisions, for instance, in the knee or abdomen. Surgery completed through a small incision and assisted with special instruments, such as the endoscope, is called keyhole surgery. 

Similarly, endoscopes can be passed into the large intestine (colon) through the rectum to examine this area of the intestine. This procedure is called sigmoidoscopy or colonoscopy depending on how far up the colon is examined. 

A special form of endoscopy called endoscopic retrograde cholangiopancreaticography, or ERCP, allows pictures of the pancreas, gallbladder, and related structures to be taken. ERCP is also used for stent placement and biopsies. 

Endoscopic ultrasound or EUS combines upper endoscopy and ultrasound examination to obtain images and information about various parts of the digestive tract. 

Because modern endoscopy has relatively few risks, delivers detailed images, and is quick to carry out, it has proven incredibly useful in many areas of medicine. Today, tens of millions of endoscopies are carried out each year.   

Here are some key points about endoscopy:

• Endoscopies are quick and relatively safe procedures.
• The first endoscope was designed in 1806.
• The main reasons for endoscopy are investigation, confirmation, and treatment.
• Endoscopy can be used to remove tumors or polyps from the digestive tract.

- Optical Endoscopy 

Optical endoscopy is the primary diagnostic and therapeutic tool for management of gastrointestinal (GI) malignancies. Most GI neoplasms arise from precancerous lesions; thus, technical innovations to improve detection and diagnosis of precancerous lesions and early cancers play a pivotal role in improving outcomes. 

Over the last few decades, the field of GI endoscopy has witnessed enormous and focused efforts to develop and translate accurate, user-friendly, and minimally invasive optical imaging modalities. From a technical point of view, a wide range of novel optical techniques is now available to probe different aspects of light–tissue interaction at macroscopic and microscopic scales, complementing white light endoscopy. Most of these new modalities have been successfully validated and translated to routine clinical practice.

- Emerging Endoscopic Technology

Although the basic platform of flexible endoscopes is similar to that devised 50 years ago, numerous recent technological advances are becoming available to the endoscopist. Novel self-propelled endoscopes and shape-conforming overtubes may permit simpler colonoscopic exams. An abundance of new imaging modalities may facilitate early detection of dysplasia and other pathologic entities. Many of these techniques remain investigational and are currently in clinical trials to determine patient benefit. Thus, as endoscopic technology and its indications progress in tandem, the endoscopist’s armamentarium continues to expand.