62 Australasian Dental Practice March/April 2007 the cutting | EDGE M agnification is becoming an increasingly important requirement for high quality contemporary dentistry. Magnifying loupes, intra-oral cameras (IOC), and surgical operating microscopes (SOM) are the three common magnification tools in use. The published literature suggests that every dental professional is at risk for an occupational musculoskeletal injury because of poor posture secondary to eyestrain, if visual enhancement aids are not used. As well as reducing the ongoing concern of eyestrain because of the sustained, demanding and intense near visual work required in dentistry, these can offer very real improvements in the quality of work undertaken whilst also improving posture. Eyestrain During intense near visual work, the ciliary muscle of the eye, which produces accommodation (focusing) and the extra-ocular muscles, which converge the visual axis of each eye on to the object of interest, become fatigued. Subconscious attempts to alter posture to improve near vision can result in musculo-skeletal complaints, as well as eyestrain. Conversely, solutions to eyestrain (such as loupes or operating microscopes) provide a major improvement to the operator’s posture. As we age, the discrepancy between the visual demands of dentistry (close visual work) and our visual abilities increases. This is particularly common above the age of 40 years. Presbyopia is a reduction in the ability to attain sharp focus for near vision. It occurs because of reduced elasticity of the lens as a consequence of normal aging, and results in blurred near vision. The unconscious desire to hold a printed text at arm’s length in order to read it is a classic sign of this condition. The contributing factors to eyestrain in dentistry include: • The need to change focus from near to far objects, e.g. from the teeth to the bracket table, patient charts, radiographs or computer screens; • Inadequate lighting on the target, e.g. because of shadowing from the lips and cheeks; • Poor visual contrast between objects of interest, e.g. because of the similar hue of tooth structure and adhesive restorative materials; • Glare from reflections of the operating light from enamel surfaces; • Glare from reflections of daylight or artificial lighting from surfaces in the workplace, or from computer screens; • Frequent movement of the object of interest (e.g. tooth or instrument), which requires tracking of the eyes; and • Other visual problems such astigmatism. Dental staff who suffer eyestrain or visual fatigue may experience the following signs and symptoms: • Temporary blurring of vision; • Difficulties in visual accommodation; • Photophobia; • A vague discomfort in the eyes; • Feelings of heaviness of the eyes; • Dull bilateral headaches; • Bloodshot eyes; • A burning and itchy sensation in the eyesk and • Increased lacrimation (tear production). 1 Intra-oral cameras Since their introduction in 1987, these have become widely used for co-diagnosis and patient education. Modern systems have benefited from improvements in image sensor technology and image display units, with compact CMOS colour cameras and LCD screens now the usual combina- tion. Using zero degree and 90 degree optics, these cameras are normally used for demonstrating to Magnification and its increasing role in clinical practice By Professor Laurence J. Walsh “every dental professional is at risk for an occupational musculoskeletal injury because of poor posture secondary to eyestrain, if visual enhancement aids are not used...”