Periorbital Surgery and Patient Eye Protection

No one questions the need to protect the eye during periorbital surgery. However, the most appropriate means of protection and standardized requirements have been the subject of some debate. The treatment of the facial tissue near the eye can potentially expose ocular tissues to scattered laser radiation that has been internally diffusely scattered around optical tissues. This is of particular concern for the more penetrating laser wavelengths within the 750-1400 nm spectral region. The use of eye patches and occluders protect the globe from direct exposure; however, scattered energy from around the protector can reach the eye. Sensitive imaging methods and a subjective method have been employed to estimate the fluence at different internal ocular structures. Sliney measured the radiance (brightness) of scattered optical radiation in the orbital area when a low-power laser was placed at several periorbital locations to quantify the level of periorbital exposure. Subjective measures of brightness have also permitted the determination of retinal exposure levels. The measured levels scaled to 1- and 10 watt laser power levels showed that significant levels of laser radiation can be transmitted to ocular tissues despite the use of lid patches, and great cau­tion must be exercised in the choice of appropriate eye protection for the more deeply penetrating wavelengths in the 600-1100 nm spectral region. Indeed, a number of acciden­tal eye injuries have been reported from inadequate precautions during laser skin resurfac­ing and hair removal in the periorbital area [16-22]. Although accidental injuries have resulted from the CO2 laser [16], injuries from the more deeply penetrating wavelengths in

the 700-850 nm region, such as diode and alexandrite lasers have been reported more fre­quently [17-22]. As one example, a patient treated for a port-wine stain in the periorbital area with a 755-nm alexandrite laser with a radiant exposure of 50 J/cm2 and 20 ms pulses having a beam diameter of 12.5 mm produced permanent injury of the iris and some reduc­tion in vision [20]. An iris atrophy was produced during diode laser epilation [17]. The CO2 laser injury of the eyes apparently took place, despite the use of metal eye-shields; how­ever, in that instance, the treatment of both eyelids with two passes as well as the entire face (a 210-minute procedure) may have overheated the metal eye shields, causing thermal damage from heat conduction to the underlying ocular tissue from the 0.25-0.3 J, 6-7 mm spots (although dislocation of the eye shields cannot be ruled out). Special eye shields are available for patient protection and normally should be opaque and in contact with the cornea and conjunctiva (Fig. 24.3).

The thickness of soft tissues in and around the orbit varies greatly with position and facial type, therefore it is very difficult to provide absolute assurance that a specific eyelid cover or even a corneal-contact metal eye shield will provide certain protection in every case. With the deeply penetrating wavelengths, some energy will definitely reach into the globe and potentially heat-pigmented tissues—most notably the iris, and to a much lesser extent, even the retina. The findings of Pham and colleagues are notable here, as they dem­onstrated retinal stimulation by scattered red light, but of course this level of multiply scat­tered light around the globe—while sufficient to see—was far below levels required to injure the retina [23]. It is worth remembering that eye shields developed and tested in the 1990s for covering the eye and protecting the cornea against excessive CO2 laser radiation may not necessarily be ideal for deep red and IR-A (780-1400 nm) wavelengths [24-27]. Surfacing of rhytides near the eye and blepharoplasty require great care to protect the eye [28]. Ocular injuries from IPL devices can also occur to the iris, but less likely to occur to the retina.