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Evaluation of corneal damage after 355-nm irradiation of rabbit eyes. Slit lamp image of rabbit eye showing second column of exposures with cumulative radiant exposures (top to bottom) of 300, 1200, and 300 J∕cm 2 after (a) 12 h and (b) 48 h. Live/dead stained corneal endothelium of 300 J∕cm 2 at (c) 12 h and (d) 48 h after laser exposure.
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A recent study showed that 355-nm nanosecond lasers cut cornea with similar precision to infrared femtosecond lasers. However, use of ultraviolet wavelength requires precise assessment of ocular safety to determine the range of possible ophthalmic applications. In this study, the 355-nm nanosecond laser was evaluated for corneal and iris damage in...
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... lamp analysis of the rabbit eyes was performed in live rab- bits under anesthesia, as described above. At the 12-or 48-h time points, the cornea was removed and the endothelium was inspected with live/dead staining. An example of rabbit cornea analysis is shown in Fig. 5. The 12-h slit lamp photo [ Fig. 5(a)] shows clearly demarcated opaque lesions, whereas the 48-h image [ Fig. 5(b)] shows opacities with more gradual boundaries. Corresponding images of the endothelium after live/dead staining show a patch of missing endothelial cells at 12 h [ Fig. 5(c)] with dead stain signal coming from exposed ...
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... lamp analysis of the rabbit eyes was performed in live rab- bits under anesthesia, as described above. At the 12-or 48-h time points, the cornea was removed and the endothelium was inspected with live/dead staining. An example of rabbit cornea analysis is shown in Fig. 5. The 12-h slit lamp photo [ Fig. 5(a)] shows clearly demarcated opaque lesions, whereas the 48-h image [ Fig. 5(b)] shows opacities with more gradual boundaries. Corresponding images of the endothelium after live/dead staining show a patch of missing endothelial cells at 12 h [ Fig. 5(c)] with dead stain signal coming from exposed stromal cells. Such an endothelial hole is ...
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... eyes was performed in live rab- bits under anesthesia, as described above. At the 12-or 48-h time points, the cornea was removed and the endothelium was inspected with live/dead staining. An example of rabbit cornea analysis is shown in Fig. 5. The 12-h slit lamp photo [ Fig. 5(a)] shows clearly demarcated opaque lesions, whereas the 48-h image [ Fig. 5(b)] shows opacities with more gradual boundaries. Corresponding images of the endothelium after live/dead staining show a patch of missing endothelial cells at 12 h [ Fig. 5(c)] with dead stain signal coming from exposed stromal cells. Such an endothelial hole is filled by irregularly shaped cells at 48 h [ Fig. 5(d)]. These endothelial ...
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... staining. An example of rabbit cornea analysis is shown in Fig. 5. The 12-h slit lamp photo [ Fig. 5(a)] shows clearly demarcated opaque lesions, whereas the 48-h image [ Fig. 5(b)] shows opacities with more gradual boundaries. Corresponding images of the endothelium after live/dead staining show a patch of missing endothelial cells at 12 h [ Fig. 5(c)] with dead stain signal coming from exposed stromal cells. Such an endothelial hole is filled by irregularly shaped cells at 48 h [ Fig. 5(d)]. These endothelial changes cor- respond well to the appearance of the lesions in slit lamp at the same times. Observation of the corneas under slit lamp over 4 weeks follow-up allowed for ...
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... whereas the 48-h image [ Fig. 5(b)] shows opacities with more gradual boundaries. Corresponding images of the endothelium after live/dead staining show a patch of missing endothelial cells at 12 h [ Fig. 5(c)] with dead stain signal coming from exposed stromal cells. Such an endothelial hole is filled by irregularly shaped cells at 48 h [ Fig. 5(d)]. These endothelial changes cor- respond well to the appearance of the lesions in slit lamp at the same times. Observation of the corneas under slit lamp over 4 weeks follow-up allowed for assessment of the healing rate of the cor- neal lesions in rabbits. As shown in Fig. 6 for laser exposures with 0.87-and 1.4-mm beam diameters, only ...
Citations
... [32][33][34][35][36] Patient safety is likely not a concern when a UV-A wavelength of 355 nm is used for intrastromal cutting because the threshold for photodamage at this wavelength is four orders of magnitude higher than for UV-B wavelengths around 250 nm, and the total energy required for dissection remains well below damage thresholds for photokeratitis. 33,34,37 However, it should be emphasized that the use of laser light at 355 nm is not essential for the feasibility of the method. IR fs pulses at 1040 nm, as commonly used in Femto-LASIK, could also be applied. ...
Correction of hyperopia requires an increase of the refractive power by steepening of the corneal surface. Present refractive surgical techniques based on corneal ablation (LASIK) or intrastromal lenticule extraction (SMILE) are problematic due to epithelial regrowth. Recently, it was shown that correction of low hyperopia can be achieved by implanting intracorneal inlays or allogeneic lenticules. We demonstrate a steepening of the anterior corneal surface after injection of a transparent, liquid filler material into a laser-dissected intrastromal pocket. We performed the study on ex-vivo porcine eyes. The increase of the refractive power was evaluated by optical coherence tomography (OCT). For a circular pocket, injection of 1 μl filler material increased the refractive power by +4.5 diopters. An astigmatism correction is possible when ellipsoidal intrastromal pockets are created. Injection of 2 μl filler material into an ellipsoidal pocket increased the refractive power by +10.9 dpt on the short and +5.1 dpt on the long axis. OCT will enable to monitor the refractive change during filler injection and is thus a promising technique for real-time dosimetry.
Light can act as an effective and strong agent for the cross-linking of biomaterials and tissues and is recognized as a safe substitute for chemical cross-linkers to modify mechanical and physical properties and promote biocompatibility. This review focuses on the research about cross-linked biomaterials with different radiation sources such as Laser or Ultraviolet (UV) that can be applied as scaffolds, controlled release systems, and tissue adhesives for cornea healing and tissue regeneration.
Heat and mass transport processes in humans occur at cellular, tissue, organ, and whole-body levels. The subfield of heat and mass transfer in the human eye provides the context for understanding the functions of the eye and to develop protective, diagnostic, and therapeutic processes. The eye is sensitive to the environment because of the absence of blood flow through parts such as cornea and lens, and the absence of thermal sensors and protective reflexes beyond blinking. Heat transfer processes in the eye comprise the continuous evaporation of the tear layer coating the corneal region of a normal eye, the thermal massage across the pupils called the transpupillary thermotherapy (TTT), and the several methods of internal tissue ablation involving lasers. Drug delivery inside the eye is an important man-made mass transfer process that includes the intravitreous and transscleral routes to medicate the retina. This chapter focuses on the exposition of heat transfer processes that drive laser surgical methods and the mass transfer processes that govern drug delivery methods to the retina. In a bridging section, discussion on the combined heat and mass transfer processes involved in the TTT-based convection-assisted drug diffusion to the retina through the vitreous humor is also provided.
Laser-assisted in situ keratomileusis (LASIK) eye surgery is increasingly common, with approximately 600,000 procedures performed each year in the United States (1). LASIK eye surgery is typically performed in an outpatient setting and involves the use of a machine-guided laser to reshape the lens of the eye to correct vision irregularities (2). Clinic A is an ambulatory surgery center that performs this procedure on 1 day each month. On February 5, 2015, the Toledo-Lucas County Health Department (TLCHD) in Ohio was notified of eye infections in two of the six patients who had undergone LASIK procedures at clinic A on January 9, 2015. The two patients experienced eye pain after the procedures and received diagnoses of infection with Mycobacterium chelonae, an environmental organism found in soil and water.
TLCHD staff visited clinic A on February 12, 2015, to review procedures associated with LASIK surgery and identify possible routes of transmission. None were immediately identified. Clinic A subsequently performed 18 LASIK procedures on February 13, 2015. Two of these 18 patients experienced eye pain in early March 2015 and were determined to have laboratory-confirmed M. chelonae. These infections were reported to TLCHD, which prompted clinic A to suspend all further LASIK procedures.
Discussions between CDC, TLCHD, and the Ohio Department of Public Health focused on opportunities for water contamination during the procedures. Although TLCHD staff reported that they did not observe obvious lapses in medication preparation or hand hygiene, they did note that clinic A used two humidifiers to maintain the 40%–50% relative humidity recommended by the manufacturer of the laser device used in the LASIK procedures (3). These cold air, reservoir style, retail humidifiers were filled with tap water and located in the operating room close to where patients were situated during the procedures. Both humidifiers contained an internal reservoir that held water during use. One of these devices used an ultrasonic nebulizer to produce a mist, whereas the other passed dry inlet air over a saturated wick. The misting humidifier had been purchased in December 2014, and the evaporative device had been in use for multiple years. CDC recommended collecting environmental samples throughout the operating room, including from the water reservoir and air output vents on each of the humidifiers.
Laboratory testing performed by CDC isolated M. chelonae from the water reservoir of the misting humidifier. Pulsed-field gel electrophoresis results indicated that three of the four patient isolates and the humidifier isolate were indistinguishable; the isolate from the fourth patient was closely related (>95% similarity). After this investigation, clinic A disposed of both humidifiers and upgraded its centralized air handling system to control both temperature and humidity in the operating room environment. No further cases have been reported after the resumption of LASIK procedures in June 2015.
