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Background: A number of ophthalmic findings including optic disc edema, globe flattening, and choroidal folds have been observed in several astronauts after long-duration space flights. The authors report the first astronaut with previously documented postflight ophthalmic abnormalities who developed new pathological changes after a repeat long-duration mission., Methods: A case study of an astronaut with 2 long-duration (6 months) exposures to microgravity. Before and after his first long-duration space flight, he underwent complete eye examination, including fundus photography. Before and after his second flight, 9 years later, he underwent fundus photography, optical coherence tomography, ocular ultrasonography, and brain magnetic resonance imaging, as well as in-flight fundus photography and ultrasound., Results: After his first long-duration mission, the astronaut was documented to have eye findings limited to unilateral choroidal folds and a single cotton wool spot. During a subsequent 6-month mission, he developed more widespread choroidal folds and new onset of optic disc edema in the same eye., Conclusion: Microgravity-induced anatomical changes that occurred during the first mission may have set the stage for recurrent or additional changes when the astronaut was subjected to physiological stress of repeat space flight.

Unlabelled: This report documents the effects of photorefractive keratectomy (PRK) in an astronaut during a 12-day Russian Soyuz mission to the International Space Station in 2008. Changing environmental conditions of launch, microgravity exposure, and reentry create an extremely dynamic ocular environment. Although many normal eyes have repeatedly been subject to such stresses, the effect on an eye with a relatively thin cornea as a result of PRK has not been reported. This report suggests that PRK is a safe, effective, and well-tolerated procedure in astronauts during space flight., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2012 ASCRS and ESCRS. All rights reserved.)

Over the years, many climbers and other visitors to high altitude have been attracted to refractive surgery in hopes of lessening their dependence on glasses. Although there has been a gradual refinement of these procedures over time, they continue to have the potential for visual changes with altitude exposure. The goal of this review is to provide guidance to clinicians as to how to better advise their patients on the pros and cons of these procedures.

Purpose: To describe the history, clinical findings, and possible etiologies of ophthalmic findings discovered in 7 astronauts after long-duration space flight, and document vision changes in approximately 300 additional astronauts., Design: Retrospective, observational examination of ophthalmic findings in 7 astronauts and analysis of postflight questionnaires regarding in-flight vision changes in approximately 300 additional astronauts., Participants: Seven astronauts with ophthalmic anomalies upon return from long-duration space missions to the International Space Station and 300 additional astronauts who completed postflight questionnaires regarding in-flight vision changes., Methods: Before and after long-duration space flight, all 7 subjects underwent complete eye examinations, including cycloplegic and/or manifest refraction and fundus photography. Six underwent postmission optical coherence tomography (OCT) and magnetic resonance imaging (MRI); 4 had lumbar punctures (LP). Approximately 300 astronauts were queried regarding visual changes during space missions., Main Outcome Measures: Refractive change, fundus photograph examination, retina OCT, orbital MRI, LP opening pressures, and examination of visual acuity data., Results: After 6 months of space flight, 7 astronauts had ophthalmic findings, consisting of disc edema in 5, globe flattening in 5, choroidal folds in 5, cotton wool spots (CWS) in 3, nerve fiber layer thickening by OCT in 6, and decreased near vision in 6 astronauts. Five of 7 with near vision complaints had a hyperopic shift ≥+0.50 diopters (D) between pre/postmission spherical equivalent refraction in 1 or both eyes (range, +0.50 to +1.75 D). These 5 showed globe flattening on MRI. Lumbar punctures performed in the 4 with disc edema documented opening pressures of 22, 21, 28, and 28.5 cm H(2)O performed 60, 19, 12, and 57 days postmission, respectively. The 300 postflight questionnaires documented that approximately 29% and 60% of astronauts on short and long-duration missions, respectively, experienced a degradation in distant and near visual acuity. Some of these vision changes remain unresolved years after flight., Conclusions: We hypothesize that the optic nerve and ocular changes we describe may result from cephalad fluid shifts brought about by prolonged microgravity exposure. The findings we report may represent parts of a spectrum of ocular and cerebral responses to extended microgravity exposure., Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article., (Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate the incidence of biopsy-proven giant cell arteritis in the Native population of Alaska., Design: Retrospective review of medical diagnostic and Current Procedural Terminology (CPT) codes., Participants: 110,000 Alaska Native patients., Methods: We conducted a retrospective review of medical diagnostic codes for temporal arteritis, giant cell arteritis, and anterior ischemic optic neuropathy in the medical records of 110,000 Alaska Native patients seen between 1983 and 2003. We examined this same database in search of the CPT code for the temporal artery biopsy procedure. We also re-examined all temporal artery biopsy specimens that had been reported as positive., Results: We identified 122 patients whose diagnostic codes matched those of giant cell arteritis, temporal arteritis, or anterior ischemic optic neuropathy. We found that of 20 temporal artery biopsies that had been performed on this group, only 4 were reported to have had positive results. On re-examination of pathologic specimens, 1 of the 4 was found not to meet the latest pathologic criteria for this disease, leaving only 3 cases of biopsy-proven giant cell arteritis. The calculated incidence of giant cell arteritis in the Alaska Native population is approximately 1/100,000 in those over 50 years old., Conclusions: Compared with previous epidemiologic studies performed worldwide, our review suggests a very low incidence of biopsy-proven giant cell arteritis among Alaska Natives.

Purpose: To report the corneal perforation and delayed collapse of the anterior chamber caused by the thorn from a devil's club plant., Methods: An 8-year-old Alaska Native girl was struck in the eye with the stalk and leaves of a devil's club plant. Although 3 thorns from the plant were found to be lodged superficially in the corneal stroma, 1 was deeply embedded to the level of Descemet's membrane. The thorn was surrounded by a stromal infiltrate. Four days after the injury, the patient suffered a sudden collapse of the anterior chamber after the deeply embedded thorn became dislodged., Results: The corneal wound was sutured, and the patient had an uneventful postoperative course., Conclusions: Our experience suggests that devil's club corneal injuries should be examined daily after the initial injury. The anterior chamber may suddenly collapse after a deeply embedded thorn becomes dislodged.

Purpose: To document the incidence and treatment of patients with severe ocular and ocular adnexal injuries during Operation Iraqi Freedom., Design: Retrospective hospital-based observational analysis of injuries., Participants: All coalition forces, enemy prisoners of war, and civilians with severe ocular and ocular adnexal injuries., Methods: The authors retrospectively examined severe ocular and ocular adnexal injuries that were treated by United States Army ophthalmologists during the war in Iraq from March 2003 through December 2005., Main Outcome Measures: Incidence, causes, and treatment of severe ocular and ocular adnexal injuries., Results: During the time data were gathered, 797 severe eye injuries were treated. The most common cause of the eye injuries was explosions with fragmentation injury. Among those injured, there were 438 open globe injuries, of which 49 were bilateral. A total of 116 eyes were removed (enucleation, evisceration, or exenteration), of which 6 patients required bilateral enucleation. Injuries to other body systems were common., Conclusions: Severe eye injuries represent a significant form of trauma encountered in Operation Iraqi Freedom. These injuries were most commonly caused by explosion trauma.

Purpose: To determine graft survival and long-term visual outcome after penetrating keratoplasty (PK) for keratoconus in patients with Down syndrome., Methods: The records of all patients with Down syndrome who received PK by the same provider were reviewed. A retrospective analysis was performed to determine long-term graft survival, incidence of graft failure, and complication rate., Results: Twenty-one PKs were performed on 18 eyes of 13 patients with Down syndrome with keratoconus. Three repeat PKs were performed for secondary graft failure. All 18 eyes had clear grafts at the most recent examination. Follow-up ranged from 4 to 88 months, with a mean of 34.9 months. The average age of patients was 42 years, with a range of 20 to 63 years. Preoperative visual acuity ranged from 20/160 to count fingers. Postoperatively, visual acuity was objectively measurable in 12 eyes of 8 patients and ranged from 20/30 to 20/200, with a mean of 20/60. Broken sutures and difficulties with unsedated suture removal complicated postoperative care in some patients., Conclusion: Clear grafts and improvements in visual acuity can be obtained after PK in patients with Down syndrome, but consideration must be given to careful postoperative care by health care providers and home support personnel.

Purpose: To document the types and causes of ocular and ocular adnexal injuries treated by United States Army ophthalmologists serving in Iraq during the Iraqi Insurgency., Design: Prospective hospital-based observational analysis of injuries., Participants: All coalition troops, enemy prisoners of war, and civilians with severe ocular and ocular adnexal injuries., Methods: We prospectively examined severe ocular and ocular adnexal injuries that were treated at the 31st Combat Support Hospital during the portion of the Iraqi Insurgency that took place from January 20 through September 12, 2004., Main Outcome Measures: Incidences and characteristics of ocular and ocular adnexal injuries., Results: During the time observed, 207 patients suffered severe ocular or ocular adnexal injuries, including 132 open globes. Blast fragmentation from munitions caused 82% of all injuries. The most common single cause of injury was the improvised explosive device (IED), which caused 51% of all injuries. Of 41 eye excisions, 24 were caused by IEDs., Conclusions: During the portion of the Iraqi Insurgency covered in our report, munitions fragments were the most common cause of ocular and ocular adnexal injuries. The single most common cause of injury was the IED, which produced devastating ocular and ocular adnexal injuries. The authors' findings indicate that polycarbonate ballistic eyewear could have prevented many, but not all, of the ocular injuries we report.

The goal of this paper is to review how preexisting ocular conditions may be affected by altitude exposure. Such preexisting conditions include dry eye problems, monocular visual loss, and potential problems following refractive surgery procedures, as well as the possible changes associated with some forms of retinal and optic nerve diseases. Although most such altitude-related visual difficulties are relatively minor, some have resulted in serious morbidity or even death at high altitude. This review will give the reader background regarding these potentially debilitating conditions in order to better prepare for exposure to high altitude environments.

Military free fall parachutists may be unaware of the risk of corneal freezing and desiccation keratitis should their goggles come off during free fall in subfreezing temperatures. We determine the incidence of ocular difficulties in military free fall parachutists and the role freezing temperatures may play in causing these problems. We found that 79% of those who responded to the survey had lost their goggles at least once during free fall and 69% experienced ocular symptoms after goggle loss. Analysis shows a 30-fold increase in the duration of symptoms in subfreezing vs. above-freezing temperatures, with the odds of the ground mission being affected at 7.3 per 100 jumps in the subfreezing group. The rate of goggles coming off per jump is 3.3 times less with >75 jumps. Contact lenses are not protective and photorefractive keratectomy was not detrimental.

Purpose: To study the changes in anterior and posterior corneal curvatures in radial keratotomy (RK) and normal eyes exposed to hypoxia using Orbscan (Bausch & Lomb) technology., Setting: Department of Ophthalmology, Madigan Army Medical Center, Tacoma, Washington, USA., Methods: At sea level, 11 RK subjects and 10 control subjects were exposed to ocular surface hypoxia in 1 eye by filtering humidified, compressed 100% nitrogen (0% oxygen) through an airtight goggle system for 2 hours. The contralateral eye was exposed to humidified, compressed air (21% oxygen) simultaneously through the airtight goggle system. Orbscan analysis was performed in each subject before and immediately after gas exposure. This analysis included measurement of the anterior axial and posterior axial corneal curvatures as well as corneal pachymetry., Results: In the RK eyes exposed to 100% nitrogen gas, there was a statistically significant flattening in the anterior axial corneal curvature (P = .0012) and in the posterior axial corneal curvature (P = .0067). Radial keratotomy and control eyes exposed to air and control eyes exposed to 100% nitrogen gas demonstrated no statistically significant change in the anterior axial or posterior axial corneal curvature., Conclusions: Corneal hypoxia induced a statistically significant flattening in the anterior axial and posterior axial corneal curvatures in eyes that had had RK. There was no significant change in these curvatures in RK eyes exposed to air and in control eyes exposed to air or 100% nitrogen gas.

Objective: To determine whether hypoxia induces refractive changes in subjects who have had laser in situ keratomileusis (LASIK) refractive surgery., Design: Prospective paired eye clinical trial., Participants: There were 20 LASIK subjects (40 eyes) and 20 myopic non-LASIK controls (40 eyes)., Intervention: Each subject had one eye exposed to ocular surface hypoxia (humidified nitrogen) by use of an airtight goggle system at sea level for 2 hours. The other eye was simultaneously exposed to humidified, compressed air (21% oxygen) with the same airtight goggle system., Main Outcome Measures: Keratometry, cycloplegic refraction, and pachymetry were compared before and after exposure by use of repeated measures analysis of variance., Results: A significant myopic shift (P: < 0.01) occurred in LASIK corneas exposed to hypoxia compared with myopic control subjects. A significant increase in corneal thickening occurred symmetrically in both LASIK and control subjects exposed to hypoxia. There was a trend toward corneal steepening (keratometry) in LASIK subjects, but this was not statistically significant., Conclusions: These results suggest that ocular surface hypoxia induces a myopic shift in LASIK subjects.

Purpose: To report excellent and stable vision in an astronaut during space flight after bilateral cataract surgery with intraocular lenses., Methods: A 60-year-old physician mission specialist astronaut developed cataracts and underwent phacoemulsification with insertion of one-piece polymethylmethacrylate intraocular lenses that had 6-mm optics bilaterally. Several months later, he flew on a space shuttle mission. Ocular examinations were performed before and after the mission, and the patient was questioned about visual changes during flight., Results: Ocular examinations demonstrated stable bilateral posterior chamber intraocular lenses. Our subject reported excellent vision during liftoff, 18 days of microgravity, changes in cabin pressure, and reentry., Conclusion: Results suggest that intraocular lenses are safe, effective, and well tolerated during space flight.

Purpose: To examine the causes signs, and symptoms of anterior capsule contraction syndrome and the response to neodymium YAG (Nd:YAG) anterior capsulotomy., Setting: Madigan Army Medical Center, Tacoma, Washington, USA., Methods: This retrospective review comprised 70 cases of phacoemulsification with foldable plate-haptic silicone intraocular lens (IOL) implantation. Patients who developed anterior capsule contraction postoperatively, defined as the anterior capsule being visible through an undilated pupil, had a radial anterior capsulotomy with an Nd:YAG laser. Variables analyzed were visual acuity, subjective complaints, associated inflammation, and IOL decentration., Results: Ten eyes of 9 patients (14%) developed anterior capsule contraction and had Nd:YAG laser radial anterior capsulotomy. Three of 9 patients reported decreased visual acuity and glare. Two other patients had chronic anterior chamber inflammation unresponsive to steroids after surgery that resolved after Nd:YAG anterior capsulotomy. Intraocular lens decentration was observed in 3 patients before the Nd:YAG capsulotomy. Posterior lens dislocation occurred in 1 patient after capsulotomy and required surgical lens exchange., Conclusion: One-piece foldable silicone IOLs may not provide enough peripheral capsule expansion.

Purpose: To describe the manifestations of infectious crystalline keratopathy caused by Candida guilliermondii in a corneal transplant performed for pseudophakic bullous keratopathy., Method: Case report., Results: Candida guilliermondii was identified as the causative organism of an indolent infectious crystalline keratopathy. Incisional lamellar biopsy provided diagnostic culture and histopathologic results. Histopathology showed aggregates of yeast elements between corneal stromal lamellae, without inflammation. The infection progressed despite a 6-week course of topical amphotericin B and an additional 6-week course of topical and oral fluconazole. Repeat penetrating keratoplasty resulted in clear graft, with no recurrent infection., Conclusions: Fungal keratopathy should be included in the differential diagnosis of infectious crystalline keratopathy. Numerous Candida species have been isolated in addition to the most common causative bacterial organism, Streptococcus viridans. Candida guilliermondii is yet one more causative agent of infectious crystalline keratopathy. Candida guilliermondii, a rare human pathogen, was resistant to medical therapy in this case.

Objective: Refractive changes at high altitude that occur after radial keratotomy (RK) may be caused by hypoxia or hypobaria., Design: A prospective study was performed to evaluate the effects of hypoxia on RK and non-RK corneas., Participants: There were 20 RK and 20 control eyes., Intervention: These eyes were subjected to ocular surface hypoxia using an air-tight goggle system at sea level for 2 hours., Main Outcome Measures: Keratometry, cycloplegic refraction, and pachymetry were evaluated using repeated measures analysis of variance., Results: A significant hyperopic shift (P < 0.0001) and corneal flattening (P < 0.0013) occurred in all subjects with RK compared with those of control subjects. Corneal thickening occurred symmetrically in both groups., Conclusions: These results suggest that refractive changes in subjects with RK occur at high altitude as a direct result of corneal hypoxia.

Purpose: To report a surgical technique for the removal of limbal dermoids., Methods: We propose a method of deep excision and lamellar keratoplasty for limbal dermoid removal., Results: This technique achieves near-normal postoperative appearance and function in patients with limbal dermoids., Conclusion: This method appears to offer an effective means of limbal dermoid removal.

Purpose: The authors prospectively analyzed refractive and pachymetric parameters during exposure to high altitude after radial keratotomy (RK) and photorefractive keratectomy (PRK)., Methods: The authors measured manifest and cycloplegic refraction, keratometry, computed video keratography, and central and peripheral pachymetry in six subjects who have undergone RK (11 eyes), six who have undergone PRK (12 eyes), and nine with myopia (17 eyes) at sea level and on three consecutive days at 14,100 feet. All measurements were repeated 1 week after subjects returned to sea level., Results: Subjects who have undergone RK demonstrated a significant and progressive increase in spherical equivalence (+0.30 +/- 0.50 diopters on day 1 and +1.52 +/- 1.01 diopters on day 3; P < 0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P < 0.004; PRK, P < 0.007; control subjects, P = 0.0006) by day 3 at high altitude. Refraction, keratometry, and pachymetry returned to baseline (P = 1.000) after return to sea level., Conclusions: Seventy-two-hour exposure to high altitude in subjects who have had RK induces a significant, progressive, and reversible hyperopic shift in refraction with corresponding video keratographic and keratometric changes. The authors hypothesize that the high-altitude hypoxic environment causes increased corneal hydration in the area of the RK incisions, which may lead to central corneal flattening and a hyperopic shift in refractive error. Subjects who have had PRK and those with myopia are not susceptible to this refractive shift. The authors' RK data suggest that the time since surgery and the amount of surgery are related to the degree of hyperopic shift during altitude exposure.

Corneal abrasions are characterized by sudden onset of eye pain, photophobia and tearing. The patient usually relates a history of recent eye trauma but may not recall an inciting event. The differential diagnosis includes direct mechanical injury, recurrent erosion syndrome, ultraviolet keratitis and infection. Most abrasions heal within 24 to 48 hours. Therapeutic modalities include cycloplegia and topical antibiotics. Other treatment methods include pressure patching, topical nonsteroidal anti-inflammatory drugs, bandage contact lenses, collagen shields, anterior stromal puncture and epithelial debridement.

Background: Previous studies documented diurnal myopic shifts in patients who have had radial keratotomy (RK). Recently, hyperopic shifts in these patients exposed to high altitude have been reported. A direct mechanical effect of reduced barometric pressure on surgically altered corneas has been theorized to cause this hyperopic shift. Another hypothesis implicates the effect of hypobaric hypoxia on the RK incisions. The authors examined the effect of a 6-hour exposure to decreased barometric pressure on 14 normal and 18 RK corneas., Methods: Cycloplegic refraction, keratometry, corneal pachymetry, and tonometry were performed on seven control subjects and nine patients who have had RK. Measurements were obtained over 8 hours at sea level on day 1 of the study. Measurements were repeated on day 2 which included a 6-hour exposure to 12,000 feet simulated altitude in a hypobaric chamber. Results were compared between subjects and control subjects to determine the effect of a 6-hour exposure to decreased barometric pressure., Results: There was no statistically significant difference in refraction or keratometry readings between control subjects and subjects who have had RK. Central corneal thickness decreased in the afternoon in RK eyes compared with control eyes. There was no clinically significant difference in intraocular pressure between subjects who have had RK and control subjects., Conclusions: A measurable hyperopic shift in RK corneas exposed to high altitude requires more than 6 hours to develop. A direct effect on corneal shape due to barometric pressure alone should produce a sudden change in refractive error. This study supports the hypothesis that a slow metabolic process is responsible for the previously documented hyperopic shifts induced by altitude. However, a barometric pressure effect requiring more than 6 hours to occur cannot be ruled out with the methodology used in this study.

Purpose: We studied the effects of altitude on four corneas that had undergone radial keratotomy and four normal corneas exposed to increasing elevation during a high-altitude excursion., Methods: We measured visual acuity, cycloplegic refraction, keratometry, and intraocular pressure at sea level and after 24-hour exposure to 12,000 and 17,000 ft., Results: We observed a significant increase in spherical equivalence (hyperopic shift) in radial keratotomy eyes exposed to altitude as compared to controls (P < .0001). The average change in spherical equivalent cycloplegic refraction from sea level to 12,000 ft was 1.03 +/- 0.16 diopters and from sea level to 17,000 ft was 1.94 +/- 0.26 diopters. We also observed a significant decrease in keratometry values at altitude as compared with control corneas (P < .0001). The average change in keratometry from sea level to 12,000 ft was 0.59 +/- 0.19 diopter and from sea level to 17,000 ft was 1.75 +/- 0.27 diopters., Conclusions: Although the specific origin of these changes is open to question, we hypothesize that hypoxic corneal expansion in the area of the radial keratotomy incisions may lead to central corneal flattening and a hyperopic shift in refractive error. The cornea that has undergone radial keratotomy appears to adjust constantly to changing environmental oxygen concentration, producing a new refractive error over a period of 24 hours or more. Additional study is required to identify with certainty the specific origin of the hyperopic shift at high altitude.

Objective: To report a possible adverse effect of topical steroid-phosphate preparations and to identify factors that may contribute to the development of this effect., Design: The medical records of five patients who developed calcium deposition in the cornea were reviewed and analyzed for possible contributing factors., Patients: Five cases of calcium deposition in the cornea associated with the use of topical steroid-phosphate preparations are described. Scrapings from the cornea and/or specimens obtained at keratoplasty were available in all cases. These cases had the following characteristics in common: use of steroid-phosphate preparations (n = 5); multiple topical drops (n = 5); penetrating keratoplasty (n = 3); presence of epithelial defects (n = 4); history of herpetic stromal keratitis (n = 3) [corrected]; and history of iritis (n = 3). A hypothesis explaining calcium deposition in association with steroid-phosphate preparations is presented., Conclusions: We recommend withdrawal of steroid-phosphate preparations in patients who develop band keratopathy.

Background: Ocular and ocular adnexal injuries, both combat-related and accidental, are common during wartime. In a combat setting, the eye is particularly vulnerable to serious injury from tiny flying particles that might minimally affect other parts of the body. The purpose of this study is to examine the incidence of serious ocular and ocular adnexal injuries that occurred during Operations Desert Shield and Desert Storm., Methods: The authors retrospectively reviewed serious ocular and ocular adnexal injuries treated by United States Army and Navy ophthalmologists that occurred during Operations Desert Shield and Desert Storm. Only those injuries that resulted in, or would have resulted in, hospital admission because of the ocular or ocular adnexal injury alone are presented., Results: During Desert Shield, 20 patients (23 eyes) suffered serious ocular or ocular adnexal injuries compared with 160 patients (198 eyes) in Desert Storm. During Desert Storm, 78% of all serious injuries were caused by blast fragmentation from munitions. More than one third of the 98 globe lacerations reported in this article were 10 mm or less in size. Of 35 enucleations performed during Desert Storm, 94% were the result of munitions fragments., Conclusions: During Operation Desert Storm, fragmentation wounds from munitions were the most common cause of ocular and ocular adnexal morbidity. The authors' findings indicate that polycarbonate ballistic protective eyewear could have prevented many of the ocular injuries that they report.

We measured intraocular pressures and retinal vascular diameters from 11 subjects during 20 seconds of microgravity produced by parabolic flight on board a KC-135 aircraft. Intraocular pressures increased 58% during parabolic flight compared to baseline values (19 +/- 1 mm Hg vs 12 +/- 1 mm Hg, respectively; P < .001). A 4% reduction in the caliber of retinal arteries was also noted during microgravity, but this change did not achieve statistical significance (7.8 +/- 0.3 pixels at zerogravity vs 8.1 +/- 0.3 pixels at 1g; P = .07). The increase in intraocular pressure and trend of arteries to constrict are thought to result from cephalad shifts in intravascular and extravascular body fluids as a result of the absence of the 1g hydrostatic gradient. The results of our study confirm that this fluid shift and its effects on the eye occur rapidly, within 20 seconds of exposure to microgravity.

Background/purpose: Selective removal of interrupted sutures and adjustment of a running suture can minimize astigmatism after penetrating keratoplasty, but the long-term effects of early suture manipulations remain largely unknown. The authors tested the hypothesis that the cornea becomes "fixed" more than 1 year after keratoplasty so that desirable refractive results will remain when all sutures are eventually removed., Methods: The authors reviewed retrospectively the changes in astigmatism that occurred when all remaining sutures were removed from 162 eyes 1 to 6 years after penetrating keratoplasty. Single-running sutures were used in 130 eyes, double-running sutures in 20 eyes, and a combination of interrupted and running sutures in 12 eyes., Results: Removal of single-running sutures caused an average decrease in astigmatism of 0.52 diopters (D) from 6.10 +/- 4.41 D to 5.57 +/- 3.14 D. However, the astigmatism in 62% of eyes changed 2 or more D (range, 11.94 to -17.87 D), and the range changed more than 20 degrees in 55% of eyes. The average vectorial change was 6.5 +/- 4.3 D (range, 0.59 to 19.8 D). There was no decrease in the amount of astigmatic change with increasing time between surgery and suture removal. Graft size and diagnosis had no effect on the amount of astigmatic change. Astigmatic errors became stable, with less than 1 D of change between successive examinations within 6 months after suture removal. Similar results were obtained for eyes with double-running and interrupted-running sutures., Conclusions: Corneal astigmatism may change unpredictably and by large amounts when all remaining sutures are removed 1 to 6 years after penetrating keratoplasty.

Spaceflight induces a cephalad redistribution of fluid volume and blood flow within the human body, and space motion sickness, which is a problem during the first few days of spaceflight, could be related to these changes in fluid status and in blood flow of the cerebrum and vestibular system. To evaluate possible changes in cerebral blood flow during simulated weightlessness, we measured blood velocity in the middle cerebral artery (MCA) along with retinal vascular diameters, intraocular pressure, impedance cardiography, and sphygmomanometry on nine men (26.2 +/- 6.6 yr) morning and evening for 2 days during continuous 10 degrees head-down tilt (HDT). When subjects went from seated to head-down bed rest, their heart rate and retinal diameters decreased, and intraocular pressures increased. After 48 h of HDT, blood flow velocity in the MCA was decreased and thoracic impedance was increased, indicating less fluid in the thorax. Percent changes in blood flow velocities in the MCA after 48 h of HDT were inversely correlated with percent changes in retinal vascular diameters. Blood flow velocities in the MCA were inversely correlated (intersubject) with arterial pressures and retinal vascular diameters. Heart rate, stroke volume, cardiac output, systolic arterial pressure, and at times pulse pressure and blood flow velocities in the MCA were greater in the evening. Total peripheral resistance was higher in the morning. Although cerebral blood velocity is reduced after subjects are head down for 2 days, the inverse relationship with retinal vessel diameters, which have control analogous to that of cerebral vessels, indicates cerebral blood flow is not reduced.

Viruses that affect the cornea produce changes that range from benign, self-limited conjunctivitis to sight-threatening scarring and vascularization of the cornea. In this article, the forms of viral keratitis most commonly encountered by the clinician are reviewed. The epidemiology, clinical presentation, and treatment of infection by Herpes simplex virus, varicella zoster virus, and the adenoviruses are discussed. Also included are other viral infections of the cornea.

We describe penetrating keratoplasty for corneal scarring in a patient with congenital sensory neuropathy and repeated self-mutilation. This patient underwent a successful penetrating keratoplasty but suffered a series of postoperative complications necessitating three repeat grafts. Some of these complications were attributable to decreased corneal sensation while others were caused by self-mutilation. Since his last penetrating keratoplasty 4 years ago, this patient has had functional visual acuity.

Gentamicin sulfate is frequently included in the initial treatment of suspected bacterial keratitis. We present the gentamicin susceptibility test results for coagulase-negative staphylococci and Staphylococcus aureus isolated from corneal ulcers in nine patients. All were resistant to gentamicin by standard disk diffusion techniques. The minimum inhibitory concentrations were very high, some exceeding the concentration normally achieved by frequent topical application of antibiotics. Clinicians should be aware that strains of staphylococci extremely resistant to gentamicin may cause keratitis. An antibiotic with broad activity against Gram-positive organisms, such as a cephalosporin or vancomycin, should be included as part of the initial therapy for corneal ulcers that might be caused by staphylococci.

Amaurosis fugax, or fleeting loss of vision, is often attributed to embolic retinovascular disease. In this setting, there is appropriate concern for associated cerebrovascular complications. Extensive and expensive vascular evaluation may be indicated. Less often, local ocular abnormalities may mimic embolic visual loss. We describe a case of sudden, transient, monocular visual loss in a 67-year-old woman caused by Valsalva-induced intraocular bleeding from a seemingly normal iris.

Intraocular pressures, retinal vascular diameters, and visual acuities of nine men (ages 19-29), were repeatedly measured while the subjects were tilted 10 degrees head-down for 48 h and while they were seated before (baseline), and after the tilt. An immediate increase in intraocular pressure, measured by pneumatonometer (4.7 +/- 0.6 mm Hg, p less than 0.001) was recorded when subjects assumed the head-down position, and diurnal variations in intraocular pressures were observed for the 48 h. The initial and final head-down intraocular pressures were not significantly different (18.9 +/- 1.2 mm Hg vs. 17.9 +/- 1.4 mm Hg, respectively). However, when subjects resumed the sitting position, intraocular pressures fell below the initial sitting values (14.2 +/- 0.9 pre vs. 11.2 +/- 0.5 post, p less than 0.04). Computer image analysis of the retinal vasculature detected a 6% and 2% reduction in the caliber of arteries and veins, respectively, as compared with sitting baseline values. No changes in visual acuity were documented during the 48 h of head-down tilt. Our data suggest that the choroidal blood reservoir increases in volume over 48 h at continuous head-down position with a compensatory decrease in aqueous volume. These findings may explain intraocular pressure changes noted in astronauts during previous space missions and in studies associated with change in body position.

The width of retinal arteries and veins was measured by digital image analysis using an automated vessel-tracking software program. Mean coefficients of variations in vessel width of less than 3% were easily achieved from digitized 35-mm retinal photographs taken with a table-top or hand-held fundus camera. Retinal images were analyzed from seven subjects exposed to sea level or altitudes equivalent to 10,000 (3048 m), 17,500 (5334 m), and 25,000 (7620 m) ft and nine subjects exposed to sea level and 14,110 ft (4300 m). At each altitude, retinal veins dilated more than did arteries (5 +/- 1 versus 0 +/- 1% at 10,000 ft and 28 +/- 9% versus 9 +/- 2% at 25,000 ft; veins versus arteries, respectively). However, widths of retinal arteries and veins were reduced in nine subjects tested after 15 minutes, 24 hours, and 48 hours of 10 degrees head-down tilt; and values varied inversely with intraocular pressures (IOP). Hand-held retinal fundus photography and digital image analysis were found to provide a sensitive and objective method for detecting and quantifying retinal vascular responses in humans exposed to novel environments.

Intraocular lenses are known to be efficacious in the correction of aphakia, but their suitability and durability in Army aviators has not been previously evaluated. Eight experienced pilots (preoperative flight time average: 7,660 hours), who had intraocular lens implants following removal of cataractus lenses, were studied. All had returned to flight duty, seven as pilots, with a total of 2,700 hours postoperative flight time accumulated. All were very pleased with the surgery and with the effectiveness of their lenses. Minor problems included: halos around lights in low illumination (5/8 pilots), erythropsia (2/8), and difficulties with a fixed focal length (2/8). Two aviators reported significant visual problems: complications associated with a platinum loop iris supported intraocular lens, and discomfort and glare stemming from traumatic corneal scarring. A detailed ophthalmological examination revealed abnormalities (5/8 pilots), but none which would be directly attributed to flying. Modern intraocular lenses appear to be an acceptable means of correcting aphakia in Army aviators.

Melanin has been previously shown to modify the mydriatic response to atropine instillation. Skin and iris pigmentation has also been shown to modify aspects of the heart rate response to injected atropine, although these observations have been generally overlooked. In this study, 20 healthy non-smoker male subjects, ages 20-30 years, were injected by two different automatic injector devices and the mydriatic and heart rate responses in the first 90 min were reported. The group included 8 brown-eyed, 4 hazel-eyed, and 8 blue-eyed subjects. Although there were differences in the rate of atropine delivery between the two injection devices, the heart rate responses were independently modified by eye color to a magnitude of difference as great as the differences between injectors. Subjects with more pigmented irides (brown-eyed) showed a more rapid rise in heart rate compared to less pigmented irides (hazel-eyed and blue-eyed subjects). Following injection by the device with a slower atropine absorption rate, these differences were particularly enhanced and an abbreviated bradycardic phase of the heart rate response was observed for the brown-eyed subjects. This observation confirms earlier reports and suggests the possibility of an interference by melanin (in the iris or elsewhere) in atropine accessibility to selected muscarinic target sites.