Publications (6)7.61 Total impact
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Article: Physiological profile of world-record-holder Sherpas.
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ABSTRACT: Tibetans and Sherpas have long been revered for their physical aptitude at high altitude, and are thought to have lived at high altitude longer than any other culture. We performed physiologic testing on 2 Sherpas who currently hold world records for: (1) most number of ascents of Mt Everest and (2) speed ascent of Mt Everest from base camp to the summit. In doing so, we describe certain physiological aspects of these individuals that may contribute to their abilities at altitude. Anthropometric measurements, blood testing, and electro- and echocardiographic examination as well as pulmonary function tests were performed. Exercise testing consisted of treadmill climbing at increasing incline and speed while wearing a 22 kg backpack in Salt Lake City (1325 m) and Park City (2063 m). Anthropometry, electrocardiography, pulmonary function, strength, and echocardiography were consistent with predicted parameters for the general population. The Sherpas demonstrated appropriate cardiopulmonary response to dynamic exercise similar to moderately fit individuals while performing treadmill testing, both at moderate and high altitude. As expected, the energetic cost increased at higher altitude, likely due to increased respiratory work. The 2 world-record Sherpa climbers were within normal ranges for the specific measurements that were tested. They displayed appropriate cardiopulmonary and physiological responses and exercise performance profiles at moderate and high altitude.Wilderness and Environmental Medicine 03/2011; 22(1):65-71. · 0.94 Impact Factor -
Article: Ultraviolet keratitis among mountaineers and outdoor recreationalists.
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ABSTRACT: Ultraviolet (UV) keratitis is a self-limited, inflammatory condition resulting in pain and temporary visual disturbance following acute UV radiation exposure. It may afflict mountaineers and other outdoor recreationalists because snow, water, and sand reflect a high percentage of UV radiation reaching the earth's surface. We examined the cases of UV keratitis that have occurred on National Outdoor Leadership School (NOLS) courses in order to better understand its epidemiology and to help prevent this affliction on wilderness expeditions. We retrospectively reviewed all cases of UV keratitis that occurred on NOLS courses from 1984-2009. Subject demographics and contributing factors were recorded and descriptive information reported. Fifteen cases of UV keratitis occurred during the study period with an overall incidence of 0.06% in those exposed. All cases occurred in mountainous or snowy terrain except one case which occurred while boating on a river. Thirteen of the 15 (87%) cases occurred in participants who were not wearing sunglasses. Two cases (13%) occurred in participants who were wearing sunglasses without side shields. Ten cases (71%) occurred in sunny conditions, and 4 cases (29%) occurred in cloudy or low visibility conditions. In all cases, symptoms resolved within 36 hours after cessation of UV exposure. Appropriate eye protection, including adequate lenses with appropriate side shields, should be worn in mountain or water environments in order to prevent UV keratitis. This data supports the conventional conception of UV keratitis as a relatively mild and self-limited condition, if treated appropriately.Wilderness and Environmental Medicine 01/2011; 22(2):144-7. · 0.94 Impact Factor -
Article: Etiologic diagnosis of corneal ulceration at a tertiary eye center in Kathmandu, Nepal.
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ABSTRACT: To determine the etiologic diagnosis of infectious corneal ulcers at Tilganga Institute of Ophthalmology, a tertiary teaching hospital in Kathmandu Nepal, from 2006-2009. This study involved a review of all microbiology records at Tilganga Institute of Ophthalmology from August 2006 through July 2009. Microbiologic records from the corneal scrapings of all patients suspected of having infectious corneal ulcers were included. Corneal scrapings were obtained from 468 patients. The average patient age was 52 years, and 55% of the affected cases were males. Microorganisms were grown from 185 of the corneal scrapings (40%). Pure bacterial cultures were obtained from 72 patients (39%), and pure fungal cultures were obtained from 113 patients (61%). Gram stain was 75% sensitive (95% confidence interval, 0.632-0.841) in identifying bacterial infection, whereas KOH prep was 80.5% sensitive (95% confidence interval, 0.718-0.871) in identifying fungal organisms. Of 72 bacterial isolates, 50 isolates (69%) were Streptococcus pneumoniae, the most common organism isolated in this study. Of 113 fungal isolates, 40 of isolates (35%) were identified as Aspergillus sp. Fungal organisms (61%) are the most common cause of infectious keratitis in this patient population. Of all organisms, S. pneumoniae was the most common organism identified. Smear microscopy is reliable in rapidly determining the etiology of the corneal infection and can be used to help guide initial therapy in this setting.Cornea 12/2010; 29(12):1380-5. · 1.73 Impact Factor -
Article: The use of glycerol-preserved corneas in the developing world.
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ABSTRACT: Corneal opacity is the third leading cause of blindness in the developing world and encompasses a wide variety of infectious, inflammatory and degenerative eye diseases. Most caes of corneal blindness are treatable with partial or full-thickness keratoplasty, provided adequate corneal tissue and surgical skill is available. However, access to sightrestoring keratoplasty in developing countries is limited by the lack of developed eye banking networks and a critical shortage of tissue suitable for transplantation. Beyond the developed world, corneal transplantation using fresh corneal tissue (FCT) is further hindered by unreliable storage and transportation facilities, unorganized distribution networks, the cost-prohibitive nature of imported tissue, unreliable compliance with medications and follow-up instructions and inadequate health and education services. Glycerol-preserved corneas overcome many of these limitations inherent to the use of FCT. As surgical innovation in lamellar corneal surgery expands the potential use of acellular corneal tissue, long-term preservation techniques are being revisited as a way to increase availability of corneal tissue to corneal surgeons throughout the developing world. Herein, we discuss the advantages of using and the applications for glycerol-preserved corneal tissue throughout the developing world.Middle East African journal of ophthalmology 01/2010; 17(1):38-43. -
Article: Corneal profile analysis after Descemet stripping endothelial keratoplasty and its relationship to postoperative hyperopic shift.
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ABSTRACT: To evaluate changes in the corneal profile after Descemet stripping endothelial keratoplasty (DSEK) using anterior segment optical coherence tomography (AS-OCT) analysis and to describe its relationship to a dynamic postoperative hyperopic shift. John A. Moran Eye Center, University of Utah, Salt Lake City, USA. In this retrospective observational study, 9 eyes had DSEK and were followed with manifest refractions and AS-OCT analysis. To assess changes in the thickness of the cornea, measurements for each AS-OCT image were taken at the vertex of the cornea, at 1.5 mm on each side of the vertex, and at the distal edges of the graft. Patients were followed for a mean of 134 days (range 46 to 228 days). Monthly Graft thinning rates were 5.2 microm per month at the vertex, 7.9 microm per month 1.5 mm from the vertex, and 26 microm per month at the edges, with the edges thinning significantly faster than the cornea vertex (P = .0024) and the points on either side of the 3.0 mm visual axis (P = .0018). The mean spherical equivalent (SE) showed an initial hyperopic shift that decreased over the ensuing 100 to 200 days postoperatively. The mean monthly postoperative SE change was -0.25 diopter (D) with a mean preoperative to postoperative SE change of +1.26 D. The donor graft underwent changes after DSEK, which may account for the induced hyperopia and its diminishment over time via changes in the posterior corneal curvature. Results suggest that intraocular lenses be targeted to -1.00 to -1.25 D of myopia for combined DSEK and cataract procedures.Journal of Cataract [?] Refractive Surgery 03/2008; 34(2):211-4. · 2.26 Impact Factor -
Article: Penetrating keratoplasty in Nepal.
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ABSTRACT: To identify indications and outcomes in a large series of penetrating keratoplasty surgeries performed in Nepal. A retrospective case series of 472 consecutive penetrating keratoplasty surgeries (408 patients) performed at Tilganga Eye Center, Kathmandu, Nepal from June 1994 to September 1999. Mean recipient age was 39.2 years (+/- 19.7 years). Main indications for PKP were corneal scar (37%), adherent leukoma (35%), perforation or impending perforation (9%), pseudophakic bullous keratopathy (6%), keratoconus (4%), and aphakic bullous keratopathy (3%). Mean duration of follow-up was 27.6 +/- 25.1 months. Sixty-five percent of available grafts were clear at 6 months, and 70% of available grafts were clear at 3 years. Six months postoperatively, 15% of patients had acuity better than 6/18, 37% had acuity between 6/18 and 6/60, and 17.7% had acuity between 6/60 and 3/60. Common causes of graft failure were endothelial failure (43%), increased intraocular pressure (15%), ulcer (14%), and trauma (7%). The corneal diseases and indications for transplant surgery in Nepal are different from those in the Western world. Despite these differences, penetrating keratoplasty is a successful and reasonable way to reduce corneal blindness in developing nations.Cornea 09/2004; 23(6):589-96. · 1.73 Impact Factor
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2011
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University of Utah
- Division of Emergency Medicine
Salt Lake City, UT, USA
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