Specular microscopy of traumatic posterior annular keratopathy.

Specular microscopic studies in two patients with traumatic posterior annular keratopathy demonstrated that the endothelial rings consist of disrupted and swollen endothelial cells. The damaged cells were still evident many days after the rings had disappeared. The amount of endothelial cell loss depends on the severity of the injury, and a measurable decrease in cell density occurs only in the more severely injured patients. A physical explanation for the occurrence of these endothelial rings is discussed.

Preoperative measurement of scotopic pupil dilation using an office pupillometer.

PURPOSE: To describe a light-amplification pupillometer designed for office evaluation of refractive surgical candidates and compare its usefulness with that of a millimeter ruler and a standard pocket-card pupillary gauge. SETTING: Center for Ophthalmic Surgery, Encino, California, USA. METHOD: The pupil sizes of 100 patients with a mean age of 28 years (range 18 to 50 years) were measured at 2 levels of illumination: 15 and 3 lumens. Pupil size was measured with a Rosenbaum pocket-card pupil gauge, a millimeter ruler, and the pupillometer at approximately 15 lumens. This level of illumination was chosen by 3 technicians as the lowest at which the pupil of a brown eye could be measured with confidence using the Rosenbaum card. Pupil size was then measured using the light-amplification pupillometer at approximately 3 lumens. This illumination level was chosen to simulate that of night-driving conditions. RESULTS: At 15 lumens, mean pupil diameter was 5.1 mm (range 2.5 to 8.0 mm). There was no difference in the measurements taken with the 3 instruments at this illumination level. At 3 lumens, the pupil diameter could not be measured with confidence using the Rosenbaum card or the millimeter ruler. Using the pupillometer, mean pupil size was 6.2 mm (range 3.0 to 9.0 mm). The mean difference in pupil diameter measured at 15 and 3 lumens was 1.1 mm (range 0.0 to 3.0 mm). CONCLUSION: This evaluation suggests that it would be difficult for clinicians to reliably predict the level of pupil dilation at 3 lumens by measuring pupil size at 15 lumens. The light-amplification pupillometer provides a tool for measuring pupil size at an illumination level that simulates night-driving conditions. The use of this device may help surgeons identify refractive surgery candidates who are more likely to be dissatisfied with their postoperative vision at low illumination levels.

Current status of lasers in soft tissue dental surgery.

The aims of this paper are to briefly describe laser physics, the types of lasers currently available for use on soft tissues focusing primarily on CO2 and Nd:YAG laser energies, the histological effects of lasers on oral tissues, laser safety, the clinical applications of lasers on oral soft tissues, and future directions. Of the two types of lasers currently available for dental applications, both the CO2 and Nd:YAG lasers can be used for frenectomies, ablation of lesions, incisional and excisional biopsies, gingivectomies, gingivoplasties, soft tissue tuberosity reductions, operculum removal, coagulation of graft donor sites, and certain crown lengthening procedures. The advantages of lasers include a relatively bloodless surgical and post-surgical course, minimal swelling and scarring, coagulation, vaporization, and cutting, minimal or no suturing, reduction in surgical time, and, in a majority of cases, much less or no post-surgical pain. CO2 lasers, compared to Nd:YAG are faster for most procedures, with less depth of tissue penetration and a well-documented history. There have been recent reports on the use of the Nd:YAG laser for periodontal scaling, gingival curettage, and root desensitization, but further research needs to be conducted. Both the CO2 and the Nd:YAG laser have limited use in conventional flap therapy.

Managing aphthous ulcers: laser treatment applied.

The recurrent aphthous ulcer is a common oral ulcerative condition. Therapies are pharmaceutical in nature, remain palliative and do not alleviate pain. Carbon dioxide laser therapy was used to treat a minor form of the ulcer (canker sore); the laser therapy reduced or eliminated the pain and inflammation with normal wound healing.

Laser surgery procedures in the operational KC-135E aviation environment.

The operational aviation and space environments present a potential for surgical trauma to aircrew and passengers. Current wound care techniques for trauma in the aviation and space medicine environment focus on classical surgical management of wounds. Medical lasers used in these environments can provide rapid control of bleeding wounds, reduce aircraft environmental contamination from body fluids and secretions, and foster rapid triage of injured personnel. Self-contained and reusable medical lasers have the potential to reduce the material supply of medical kits in the aviation and space environment. A miniaturized carbon dioxide laser was used to establish protocols and procedures for use on operational military KC-135E aircraft. Laser surgery was performed to demonstrate laser efficacy and safety in flight.

Smokeless tobacco-induced lamellar body abnormalities.

OBJECTIVES: To compare the morphological changes and quantitative distribution of lamellar bodies (Lb) (membrane coating granules) in the hamster cheek pouch epithelium with smokeless tobacco (ST). MATERIALS AND METHODS: Archives of experimental material from previously published studies [S. Ashrafi, A. Das, R. Worawongvasu, B. Mehdinejad and J. Waterhouse (1992) Scanning Microscopy6: 183] were utilized. Animals in experimental group received most ST (snuff) in their right pouch, 5 days weekly, for 24 months, while no snuff was given to control group. After 24 months, the epithelial tissues were processed for electron microscopic study. Volume densities of Lb were assessed by morphometry. MAIN OUTCOME MEASURES: Densities of Lb in the two groups, experimental vs control. RESULTS: In the control, Lb extruded their contents into the intercellular spaces of upper granular layers and in between the last granular cell layers and keratin layers to form a permeability barrier. Conversely, in the smokeless tobacco-treated epithelium, the majority of the Lb that were formed remained inside and accumulated within the granular cells, without extruding their contents into the intercellular spaces to form a lipid compound permeability barrier. CONCLUSIONS: Commercial alkaline ST may have contributed to the abnormal accumulation of Lb in the granular cell layer and affected the extrusion process of Lb to form an incomplete permeability barrier in the oral epithelium.

Future directions of lasers in dental medicine.

Dental practitioners continue to serve as leaders in the development of laser applications for dental surgery. Laser wavelengths ranging from the ultra-violet excimer lasers to the far-infrared carbon-dioxide lasers are now used in dental research with greater frequency. By using new and emerging laser media, researchers can now demonstrate advances in the fields of laser diagnostics, photocoagulation, photoablation, and laser tissue-welding. Dental laser therapy is rapidly emerging as an increasingly significant portion of the dental armamentarium. As advances in laser media and miniaturized delivery systems continue, dental laser research will continue to focus on the risk-benefit ratios and viability of specific laser applications. This paper reviews significant laser research of the past year, covering such areas as laser history, laser types, and laser biophysics. Finally, the future implications for dentistry of the most recent advances in laser therapies on hard and soft tissues is reviewed.

Mitochondrial volume densities in the smokeless tobacco-treated hamster cheek pouch epithelium.

OBJECTIVES: To compare the morphological changes and quantitative distribution of mitochondria in the hamster cheek pouch (HCP) epithelium treated with smokeless tobacco (ST). MATERIALS AND METHODS: Archives of experimental material from previously published studies (Ashrafi et al., 1992) were utilized. Animals in experimental group received moist ST (snuff) in their right pouch, 5 days weekly for 24 months, while no snuff was given to control group. After 24 months, the epithelial tissues were processed for electron microscopy study. Volume densities of mitochondria were assessed by morphometry. MAIN OUTCOME MEASURES: Mitochondrial volume densities in the two groups, experimental vs control. RESULTS: In both control and experimental groups mitochondria were concentrated between the nucleus and basal cell plasma membrane. A decrease in the mean mitochondrial volume density (Vvmit) was observed from the basal layer to the more superficial layers in both groups. The experimental HCP displayed more mitochondria than control, and the granular epithelial cell layer in experimental group showed significantly a higher mean Vvmit than the control group (P = 0.03). It was concluded that greater numbers of mitochondria were retained in ST-treated granular cells of the hyperplastic epithelia than in the normal epithelium.

Amyl nitrite: use as a smooth muscle relaxant in difficult preterm cesarean section.

Amyl nitrite is a smooth muscle relaxant that has been used clinically to facilitate uterine relaxation in difficult deliveries. In this retrospective study, we evaluate the safety of amyl nitrite use during preterm cesarean deliveries, and we assess possible advantageous effects on surgical incision choice. Women who received amyl nitrite cesarean section were compared to a control group matched for gestational age, fetal presentation, and mode of delivery who did not receive amyl nitrite. There were no statistical differences between the groups in the independent variables (maternal age, parity, medical or obstetric history, type of anesthesia, anesthesia or obstetric attending physician, antepartum hematocrit, or neonatal weight). Outcome (dependent) variables (estimated blood loss, Apgar scores, postpartum hematocrit, cord gases, or postpartum complications) were assessed, and there were no significant differences between the groups. Low transverse cesarean section was performed more frequently in the amyl nitrite group (58 of 64) than in the comparison group (48 of 64) (p less than 0.03). Considering the 128 women with and without amyl nitrite together, the decrease in hematocrit observed postpartum was greater after classic section (7%) than after low transverse section (4%) (p less than 0.002). We conclude that the use of amyl nitrite during preterm cesarean section poses no threat to mother or fetus and may facilitate delivery by allowing the performance of a low transverse rather than a classic cesarean section without maternal or neonatal complications.

Comparison of the accuracy of the Binkhorst, Colenbrander, and SRK implant power prediction formulas.

The prediction accuracy of the Binkhorst, Colenbrander, and SRK formulas were compared in five series from different sources totalling 654 cases. The SRK formula was superior to both the other formulas by having a smaller average error per case, a smaller range of error from highest minus to highest plus, and a smaller proportion of cases with greater than 2 diopters (D) of error in all five series studied. In four of the five series, the SRK formula also had the greatest proportion of cases with less than 1 D of error. The Colenbrander formula was superior to the Binkhorst formula in all five series with regard to average error, proportion of cases with less than 1 D of error, and proportion of cases with more than 2 D of error. The range of error from highest minus to highest plus was equivalent with the two formulas. All available published literature on the accuracy of implant power prediction formulas was reviewed and appears to support our findings.