The Chain is Only as Strong as its Weakest Link: Understanding the Endoscopic Optical Chain

Review Article

Austin J Obstet Gynecol. 2014;1(3): 5.

The Chain is Only as Strong as its Weakest Link: Understanding the Endoscopic Optical Chain

Milad MP1*, Moy I2 and Pavone ME1

1Department of Obstetrics and Gynecology, Feinberg School of Medicine at Northwestern University, USA

2Kaiser Permanente, Center for Reproductive Health, USA

*Corresponding author: Magdy Milad, Department of Obstetrics and Gynecology Division of Reproductive Endocrinology and Infertility, Feinberg School of Medicine at Northwestern University, 250 Superior Street, Suite OS 2177, Chicago, IL 60611, USA

Received: July 25, 2014; Accepted: August 20, 2014; Published: August 22, 2014

Abstract

A basic understanding of the components of the optical chain, as well as a guide to overcoming common problems, continue to be integral to safe and effective patient care. A thorough comprehension of the optical chain will enable one to effectively troubleshoot basic problems leading to stellar image displays and safer patient care in the operating room.

Keywords: Laparoscopy; Optical chain; Safety

Introduction

The first references to endoscopy dates back to ancient times when Hippocrates described performing a rectal exam with a speculum. Prior to the 19th century, the interior of the body could only be examined through orifices aided by the use of candlelight [1]. In the early 19th century, Phillip Bozzini, Pierre Segalas, Francis Cruise and John Fisher used gas lamps and candles with reflectors to better visualize the gastrointestinal tract [1-3]. This method of access also allowed for therapeutic procedures, including lithotripsy. In the 20th century, collaborations between engineers, physicians and optical instrument creators set the stage for the development of the field of endoscopy [1,4]. Following the introduction of the computer chip television camera, enlarged views of the operative field were projected onto a monitor, freeing the operating surgeon's hands and facilitating the performance of complex laparoscopic procedures [5,6].

Laparoscopic surgery has increasingly become accepted as an alternative to traditional open gynecologic cases. In 2003, Wu et al reported an increase in the laparoscopic hysterectomy rates in the United States, accounting for 12% of all hysterectomies performed [7]. With continued advances in laparoscopic procedures including the FDA's approval of Da Vinci laparoscopy for gynecologic surgery in 2005, operative options for clinicians and patients have continued to expand. Recently, the AAGL took the position that most hysterectomies for benign disease should be performed either vaginally or laparoscopically [5,7]. Notwithstanding the continued improvements in minimally invasive surgery, a surgeon's understanding of the optics of endoscopic surgery still remain paramount to safe and effective patient care [8-11]. In this article, we will review the components of the optical chain. A surgeon's ability to properly utilize the armamentarium afforded to him or her in the operating room relies on his/her understanding of how the multiple components of the system work together. Since "the chain is as strong as the weakest link", a thorough comprehension of the optical chain will enable one to effectively troubleshoot basic problems leading to stellar image displays and safer patient care in the operating room [6,9].

The optical chain

With the development of lighted tubes in the 19th century, surgeons were able to look into body cavities to obtain more diagnostic information than was previously available [1]. This was one of the initial developments which made endoscopy feasible. The first documented laparoscopy, performed by Dimitri Oskarovich Ott in 1901, used a gynecologic hand mirror, an external light source and a speculum [1,12]. The development and use of fiberoptic bundles in 1957 revolutionized the field and set the stage for the first laparoscopic appendectomy performed by gynecologist Kurt Semm in 1981 [4,13,14]. This type of fiber optic light cable is still used today. The modern day optical chain commonly consists of an endoscope, fiber optic light cable, light source, camera head, video signal box, video cable, and display monitor. An interruption in this chain can lead to poor imaging, which can greatly compromise the safety of the surgery. The component parts, when connected properly, make visualization possible. The image quality itself is judged by its sharpness and clarity, which are collectively referred to as "resolution" [8,9]. The image is only as good as its weakest component.

System Components

The endoscope

In gynecologic surgery, the laparoscope provides the appropriate magnified image of a patient's abdominal and pelvic cavity [1]. The objective or distal lens creates the image while the ocular or proximal lens provides magnification. In rigid scopes, rod shaped glass lenses transmit the image from the objective to the proximal lens. With repeated sterilization, condensation can accumulate within lenticular spaces between lenses disrupting the image. Optical glass fibers transmit the images in semi-rigid and flexible endoscopes. The fiber optic cable and bundle in the laparoscope must be in working order to deliver a crisp and optimal image [6,9]. Rigid endoscopes come in a variety of angles from 0 to 120 degrees to facilitate visualization (Figure 1).