THE UNPROTECTED HUMAN EYE is extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. The site of ocular damage for any given laser depends upon its output wavelength. Laser light in the visible and near infrared spectrum 400 - 1400 nm (the majority of lasers used in dermatology) contributes to the so-called "retinal hazard region" and can cause damage to the retina, while wavelengths outside this region (i.e., ultraviolet and far infrared spectrum) are absorbed by the anterior segment of the eye causing damage to the cornea and/or to the lens. The extent of ocular damage is determined by the laser irradiance, exposure duration, and beam size. As laser retinal burns may be painless and the damaging beam sometimes invisible, maximal care should be taken to provide protection for all persons in the laser suite including the patient, laser operator, assistants, and observers. Protective eyewear in the form of goggle, glasses, and shields provides the principal means to ensure against ocular injury, and must be worn at all times during laser operation. Laser safety eyewear (LSE) is designed to reduce the amount of incident light of specific wavelength(s) to safe levels, while transmitting sufficient light for good vision. In accordance with the ANSI Z136.3 (1988) guidelines, each laser requires a specific type of protective eyewear, and factors that must be considered when selecting LSE include: laser wavelength and peak irradiance, optical density (OD), visual transmittance, field of view, effects on color vision, absence of irreversible bleaching of the filter, comfort, and impact resistance. Ignorance of any of these factors may result in serious eye injury. As LSE often look alike in style and color, it is important to specifically check both the wavelength and OD imprinted on all LSE prior to laser use, especially in multi-wavelength facilities where more than one laser may be located in the same room. Color coding of laser handpieces and LSE may help to minimize confusion. LSE should not move between laser rooms, nor should they be carried in lab coat pockets between use. The integrity of LSE must be inspected regularly since small cracks or loose fitting filters may transmit laser light directly to the eye. With the enormous expansion of laser use in medicine, industry and research, every facility must formulate and adhere to specific safety policies that appropriately address eye protection.

C-mount

The lens mount is an interface that allows a lens to be attached to an interchangeable lens camera. As of 2018, Canon has produced 8 mainstream lens mounts.However, a lens mount does not exist simply as a means of attaching a lens to the camera. It also facilitates communication between the camera and the lens, enabling both to perform a wide range of functions.Canon’s first mount was a standard-thread-type screw mount that supported the mechanisms found in rangefinder cameras. Subsequent mounts evolved with the times in order to meet users’ expectations, delivering such advancements as automatic aperture, auto-exposure and autofocus mechanisms.The newest mount, the RF mount, promises even better image quality and usability thanks to its large mount diameter, short back focus distance and enhanced lens-camera communication system. It is indeed a mount designed for the future.It can be said that the lens mount is the key to the future evolution of both lenses and cameras.

T-mount

A spigot mount supporting TTL metering at maximum aperture and featured a predecessor of the automatic exposure (AE) mechanism.

From the Lions Laser Skin Centre, Division of Dermatology, Vancouver Hospital & Health Sciences Centre, and University of British Columbia, Vancouver, B.C.

Presented at the American Academy of Dermatology Annual Meeting Poster Session, Washington, D.C. February 10-15, 1996

Mirrorless camera

Lensmount

2. The Nominal Hazard Zone (NHZ) is the physical space in which direct, reflected or scattered laser radiation exceeds the MPE. LSE must be worn within the NHZ.

1. Maximum permissible exposure (MPE), is the level of laser radiation to which a person may be exposed without hazardous effects or biological changes in the eye. MPE levels are determined as a function of laser wavelength, exposure time and pulse repetition. The MPE is usually expressed either in terms of radiant exposure in J/cm2 or as irradiance in W/cm2 for a given wavelength and exposure duration.

In 2018, Canon unveiled the new RF lens mount. There were a number of different types of lens mount that came before it. What features did these lens mounts have, and how have Canon mounts evolved throughout the years? Watch this video to find out.

We thank the Massachusetts General Hospital Dermatology Laser Center for providing us with some of the photographs used in this poster.