Near-simultaneous great earthquakes at Tongan megathrust and outer rise in September 2009.

The Earth's largest earthquakes and tsunamis are usually caused by thrust-faulting earthquakes on the shallow part of the subduction interface between two tectonic plates, where stored elastic energy due to convergence between the plates is rapidly released. The tsunami that devastated the Samoan and northern Tongan islands on 29 September 2009 was preceded by a globally recorded magnitude-8 normal-faulting earthquake in the outer-rise region, where the Pacific plate bends before entering the subduction zone. Preliminary interpretation suggested that this earthquake was the source of the tsunami. Here we show that the outer-rise earthquake was accompanied by a nearly simultaneous rupture of the shallow subduction interface, equivalent to a magnitude-8 earthquake, that also contributed significantly to the tsunami. The subduction interface event was probably a slow earthquake with a rise time of several minutes that triggered the outer-rise event several minutes later. However, we cannot rule out the possibility that the normal fault ruptured first and dynamically triggered the subduction interface event. Our evidence comes from displacements of Global Positioning System stations and modelling of tsunami waves recorded by ocean-bottom pressure sensors, with support from seismic data and tsunami field observations. Evidence of the subduction earthquake in global seismic data is largely hidden because of the earthquake's slow rise time or because its ground motion is disguised by that of the normal-faulting event. Earthquake doublets where subduction interface events trigger large outer-rise earthquakes have been recorded previously, but this is the first well-documented example where the two events occur so closely in time and the triggering event might be a slow earthquake. As well as providing information on strain release mechanisms at subduction zones, earthquakes such as this provide a possible mechanism for the occasional large tsunamis generated at the Tonga subduction zone, where slip between the plates is predominantly aseismic.

Long-term visual acuity, retention and complications observed with the type-I and type-II Boston keratoprostheses in an Irish population.

AIM: To evaluate the outcomes of the type-I and type-II Boston keratoprostheses in a single Irish centre. METHODS: A retrospective chart review of keratoprosthesis implantations carried out in our institution from November 2002 to March 2014 was performed. All procedures were performed by a single surgeon (WP). RESULTS: Thirty-four keratoprosthesis implantations were carried out in 31 patients with a mean follow-up of 42±31 months (range 2-110 months). Seventeen patients were female (54.8%) and 14 were male (45.2%). The majority of keratoprostheses implanted were type-I (31/34, 91.2%), and three were type-II (3/34, 8.8%). Twenty-nine patients (85.3%) had an improvement in distance best-corrected visual acuity (BCVA) from baseline. Fifty per cent (17/34) of patients had a best-ever BCVA of at least 6/12. Eighteen patients (64.3%) retained a BCVA of at least 6/60 at 1 year. Over the course of follow-up, six keratoprostheses were explanted from six eyes of five patients, one of which was a type-II keratoprosthesis. Twenty-six patients (76.5%) developed postoperative complications. Complications included retroprosthetic membrane (18 patients, 52.9%), an exacerbation or new diagnosis of glaucoma (6 patients, 17.6%), endophthalmitis (5 patients, 14.7%) and retinal detachment (2 patients, 5.9%). CONCLUSIONS: These data demonstrate excellent visual acuity and retention outcomes in a cohort with a long follow-up period in a single centre. Complications remain a considerable source of morbidity. These outcomes provide further evidence for the long-term stability of type-I and type-II Boston keratoprostheses in the management of patients in whom a traditional graft is likely to fail.

Sleep-stage-dependent Cheyne-Stokes respiration after cerebral infarct: a case study.

Polysomnographic studies of nocturnal sleep were performed on a 63-year-old women. Sleep-onset and sleep-maintenance insomnia dated back to a cerebral infarction at age 53, which resulted in bilateral cerebral injury. Two patterns of respiration were observed, and both were sleep-stage-dependent. Classic Cheyne-Stokes respiration predominated during slow-wave sleep and stages 1 and 2. REM sleep, in contrast, was associated almost exclusively with normal respiration. Recurrent brief arousals, temporally linked to the Cheyne-Stokes pattern of respiration, markedly disturbed sleep stages 1 and 2 and appeared related to the patient's subjective sleep complaints. During waking, REM, and NREM sleep, respiration is known to have different sensitivity to CNS and peripheral controls. The selective association of Cheyne-Stokes respiration with NREM sleep in this patient supports the view that anatomically separate CNS mechanisms regulate respiration in REM and NREM sleep.

Primary varicella-zoster keratitis: diagnosis by polymerase chain reaction.

PURPOSE: To report the value of polymerase chain reaction in the diagnosis of a worsening corneal ulcer. METHODS: A 6-year-old boy underwent an emergent penetrating keratoplasty for a corneal ulcer that continued to worsen despite intensive antibiotic therapy. RESULTS: Examination of the corneal specimen by polymerase chain reaction was positive for varicella-zoster virus but negative for herpes simplex. Based on polymerase chain reaction studies, we diagnosed primary varicella-zoster keratitis with corneal perforation. Electron microscopy showed herpetic virus particles in the cornea. CONCLUSIONS: Polymerase chain reaction analysis of corneal buttons at the time of penetrating keratoplasty may benefit patients with undiagnosed recalcitrant corneal ulcers.

Welding arc maculopathy and fluphenazine.

A 45-year-old male patient presented with a bilateral maculopathy following unprotected exposure of less than two minutes' duration to a manual metal arc welding unit. He had been receiving the drug fluphenazine for the previous 10 years for treatment of depression. We believe that the drug fluphenazine, which had accumulated in his retinal pigment epithelium, may have rendered him particularly susceptible to retinal photic damage.

Acyclovir ointment plus topical betamethasone or placebo in first episode disciform keratitis.

Thirty patients with first episode disciform keratitis and with no previous steroid exposure were randomly assigned to double blind treatment with 3% acyclovir ointment and 0.1% betamethasone (Betnesol) drops or acyclovir ointment and matching placebo. In the steroid group 14 of the 15 patients healed in a mean time of 21.8 days. In the placebo group eight of the 13 patients healed in a mean time of 34.5 days. The difference in mean healing time between the two groups was significant (p < 0.05). The cumulative rate of healing was also quicker in the steroid group when compared with the placebo group (p < 0.001). Other clinical parameters improved more favourably in the combination treatment group. Four patients, two in either group, experienced a mild transient punctate epitheliopathy, but no other serious adverse effects were noted. There has been no significant difference in the recurrence rate between the two groups after a mean follow-up period of approximately 3 years.

Randomised double-blind trial of bromovinyldeoxyuridine (BVDU) and trifluorothymidine (TFT) in dendritic corneal ulceration.

The results of a randomised double-blind clinical trial of 0.1% bromovinyldeoxyuridine (BVDU) and 1% trifluorothymidine (TFT) in 60 patients with corneal dendritic ulceration are presented. There was no significant difference between BVDU and TFT in terms of numbers of ulcers healed (p = 0.61), mean healing time (p = 0.065), and cumulative healing rate (p = 0.058). No serious side effects were observed, though transient stinging was recorded in five patients receiving TFT and in three patients receiving BVDU. One patient in the group treated with TFT developed a punctate epitheliopathy.

Adherence of human lens epithelial cells to conventional poly(methyl methacrylate), heparin-surface-modified, and polyHema lenses.

We developed an in vitro model to assess the adherence of human lens epithelial cells to three types of intraocular lenses: poly(methyl methacrylate) (PMMA), heparin-surface-modified PMMA (HSM-PMMA), and polyHema. Lenses were incubated with a fixed number of human lens epithelial cells. Adherent cells were counted after 72 hours in culture. Scanning electron microscopy showed significantly fewer cells adhering to the HSM-PMMA and polyHema lenses than to the PMMA lenses (P < .01). Repeat experiments on cell lines established from different donors confirmed these findings.

Daunomycin as an inhibitor of human lens epithelial cell proliferation in culture.

Posterior capsule opacification is still a major complication of both extracapsular cataract extraction and phacoemulsification. We evaluated the effects of the anti-proliferative agent daunomycin on cultured human and bovine lens epithelial cell viability and proliferation. After ten minutes of exposure, low concentrations of the agent markedly inhibited the proliferation of both cell types. The calculated LD50 for the drug against human cells was 2.20 micrograms/ml and against the bovine cells was 0.38 microgram/ml. The bovine cells appeared to be slightly more susceptible to the drug's effects, although this difference was not marked. Our results indicate that daunomycin is a potent inhibitor of both human and bovine lens epithelial cells in the laboratory.

Patient pain during different stages of phacoemulsification using topical anesthesia.

PURPOSE: To assess the pain experienced by patients during the different stages of phacoemulsification cataract surgery performed under topical anesthesia. SETTING: Ophthalmic teaching hospital, Dublin, Ireland. METHODS: This prospective study comprised 100 consecutive patients having phacoemulsification under topical anesthesia. Patients were asked to grade the pain they experienced during the different stages of the procedure using a visual analog pain scale from 0 to 10. The pain experienced during the procedure was compared with that experienced after the instillation of a drop of amethocaine. RESULTS: The overall mean pain score was 1.46. The highest mean pain score, which was during the phacoemulsification stage of the procedure, was not significantly more than the score for the administration of the topical anesthetic agent. The duration of surgery was not related to the level of pain during the procedure. CONCLUSIONS: Topical anesthesia was effective in phacoemulsification cataract surgery. Because the highest mean score was not significantly higher than that for the administration of the anesthetic agent, it is possible to counsel patients before surgery that the pain they experience during the procedure will be no worse than that during administration of the anesthetic drops.

Preoperative pupil fatigue.

Pupils are frequently dilated on the day before cataract surgery and for retinal detachment surgery so the fundus can be examined. This may, however, interfere with pupil mydriasis on the day of surgery. This study looked at the effect of pupil dilation with tropicamide 1% and with cyclopentolate 1% on pupil mydriasis 24 hours later, using phenylephrine 10% and cyclopentolate 1%, in 40 cataract patients. The pupils dilated with cyclopentolate one day previously demonstrated a mean reduction in subsequent mydriasis of 0.73 mm compared with pupils that had been dilated with tropicamide (P less than .0001). The magnitude of this difference was not related to the patient age (P = .12) or to iris color (P = .21). If it is necessary to dilate pupils on the day before surgery, tropicamide 1% rather than cyclopentolate 1% should be used, as it is less likely to interfere with the pupil mydriasis produced with cyclopentolate 1% and phenylephrine 10% on the day of surgery.

Effect of topical cyclosporin A on conjunctival T cells in patients with secondary Sjögren's syndrome.

The effect of topical cyclosporin A on conjunctival T cells was studied in nine patients with secondary Sjögren's disease. Patients had conjunctival biopsies performed before and after a 6-week course of topical cyclosporin. Epithelium and substantia propria in the Sjögren's patients before treatment showed significantly more CD4+ cells than specimens taken from nine age- and sex-matched controls. Following treatment with topical cyclosporin, there was a significant reduction in the number of CD4+ cells in both the conjunctival epithelium and substantia propria. Despite the fact that the treatment resulted in immunopathological improvement, the clinical benefit was not as favorable. Our results suggest that topical cyclosporin may have a local immunosuppressive effect on the conjunctiva in patients with Sjögren's disease.

Keratoprosthesis: preoperative prognostic categories.

PURPOSE: Recent advances aimed at preventing and treating complications after keratoprosthesis surgery have improved prognosis, but it has been suspected that various preoperative diagnoses may carry substantially different postoperative outcomes. This article attempts to clarify the ranking of prognostic categories for patients undergoing keratoprosthesis surgery. METHODS: A retrospective review of the outcome in a recent series of 63 patient eyes operated at the Massachusetts Eye and Ear Infirmary between 1990 and 1997 and followed up for a minimum of 21 months. Anatomic retention of the device and the loss of vision caused by complications were recorded. The patients were divided into four categories according to preoperative cause. RESULTS: Anatomically, one keratoprosthesis extruded spontaneously. Another 10 were permanently removed because of complications. Of the 63 eyes, 10 never achieved a visual acuity of at least 20/200 vision because of preexisting retinal or optic nerve damage. The remaining 53 had a visual acuity of 20/200 to 20/20 as follows: Stevens-Johnson syndrome (n = 7), after 2 years: 33%, after 5 years: 0%; chemical burn (n = 17), after 2 years: 64%, after 5 years: 25%; ocular cicatricial pemphigoid (n = 20), after 2 years: 72%, after 5 years: 43%; graft failure in noncicatrizing conditions (dystrophies, degenerations, or bacterial or viral infections) when a repeat graft was expected to have a poor prognosis (n = 19), after 2 years: 83%, after 5 years: 68%. The difference in outcome between the Stevens-Johnson syndrome outcome group and the graft failure group or the ocular cicatricial pemphigoid group was statistically significant. In the group of 53 eyes, visual acuity was restored to 20/200 to 20/20 for a cumulative total of 138 years. CONCLUSION: Outcome of the keratoprosthesis surgery varied markedly with preoperative diagnosis. Most favorable was graft failures in non-cicatrizing conditions, whereas Stevens-Johnson syndrome was the worst. Ocular cicatricial pemphigoid and chemical burns occupied a middle ground. The difference between the groups seemed to correlate with the degree of past preoperative inflammation.

Herpes zoster peripheral ulcerative keratitis in patients with the acquired immunodeficiency syndrome.

The purpose of this study was to describe the clinical characteristics and course of peripheral ulcerative keratitis (PUK) secondary to herpes varicella-zoster virus in patients with the acquired immunodeficiency syndrome (AIDS). Three AIDS patients with ocular herpes zoster infection (mean age at onset, 33.0 years; range, 30-42) developed PUK. The three patients had skin involvement, and two of them had bilateral keratouveitis. All were treated with high-dose oral acyclovir (4 g/day) with or without topical antiviral therapy. Two of the patients responded well to oral acyclovir, but one of them stopped the treatment, and bilateral progressive outer retinal necrosis and lethal encephalitis developed. The third patient had a recurrent episode of inflammation with PUK, extensive stromal scarring, and deep neovascularization. AIDS patients with herpes varicella-zoster virus infection may have severe and protracted corneal manifestations, including PUK. The correct diagnosis and aggressive early long-term systemic antiviral treatment must be instituted to control inflammation, ulcer progression, and complications.

Pseudohypohyperparathyroidism: a case study of differential resistance to parathyroid hormone.

OBJECTIVE: To present a rare case of a combination of hyperparathyroidism and hypoparathyroidism in a 30-year-old woman. METHODS: We review the laboratory, radiographic, and pathologic findings in a healthy-appearing woman who sustained a patellar fracture after a simple fall at home. RESULTS: Our patient had features of hypoparathyroidism--that is, tetanic crises and hypocalcemia--and also hyperparathyroidism--fracture of the patella, multiple bone cysts, and confirmed osteitis fibrosa cystica on bone biopsy specimens. These features were associated with a high serum level of intact parathyroid hormone (PTH) and parathyroid hyperplasia. A lack of response of nephrogenic cyclic adenosine monophosphate (cAMP) to PTH stimulation was observed along with subnormal serum cAMP responses. In contrast, urine phosphate excretion increased after administration of PTH. CONCLUSION: These results demonstrate a state of renal PTH resistance in a patient with osteitis fibrosa cystica.

Expression of collagens I, III, IV and V mRNA in excimer wounded rat cornea: analysis by semi-quantitative PCR.

A semi-quantitative polymerase chain reaction (PCR) methodology was used to evaluate the kinetic changes occurring in collagens I, III, IV and V mRNA in rat cornea following excimer laser keratectomy. cDNA was synthesized from RNA extracted from rat cornea at various times following excimer laser photoablative keratectomy. Collagen cDNA sequences were subsequently amplified using specific sets of oligonucleotide primers. Competitive PCR amplification was carried out using an internal standard so that a semi-quantitative analysis of message for synthesis of collagen types I, III, IV and V could be performed and time course dynamics of message for these collagens studied. There was a biphasic increase in the levels of collagens III, IV and V mRNA following excimer laser keratectomy. Collagen I mRNA levels demonstrated a more sustained increase and were still elevated at 6 weeks following wounding. Collagens IV and V mRNA showed the largest increase with an approximate three fold increase over controls between 4 days and 1 week. Our results demonstrate that upregulation of stromal collagens I, III, and V mRNA and basement membrane collagen IV mRNA occurs in rat cornea following excimer laser keratectomy.

Bromovinyldeoxyuridine (BVDU) and trifluorothymidine (TFT) in dendritic corneal ulceration: a double blind controlled study.

Fifty patients with corneal dendritic ulceration were randomly entered into a double blind clinical trial comparing BVDU eyedrops with TFT eyedrops. Of those receiving TFT 100% healed in a mean time of 6.7 days, while 92% of those receiving BVDU healed in a mean time of 8.7 days. There was no statistical difference between the two groups in terms of numbers healed, but BVDU was significantly slower in terms of days to heal. After a mean follow-up period of 7.5 months there has been one recurrence in each group.

Topical ciprofloxacin in the treatment of blepharitis and blepharoconjunctivitis.

An international multicentre study assessed the clinical and antibacterial efficacy of a new topical ophthalmic formulation of the quinolone antimicrobial agent ciprofloxacin and compared it with that of tobramycin ophthalmic solution in patients with blepharitis and blepharoconjunctivitis. The study consisted of a randomised double-masked between-group evaluation of 464 patients, 230 of whom were treated with ciprofloxacin and 234 with tobramycin. There was qualitative and quantitative bacteriology, and clinical assessment of ocular symptoms and signs before and after a seven-day course of treatment. Bacteriological cultures demonstrated eradication or reduction of potentially pathogenic bacteria in 93.7% of eyes (ciprofloxacin) versus 88.9% of eyes (tobramycin), seven days after starting treatment. Clinically more than 80% of patients in both treatment groups were cured or improved after seven days. No statistically significant differences were observed between the two treatment groups. No serious side-effects were observed after use of either antimicrobial agent. Ciprofloxacin ophthalmic solution appears safe and effective. The spectrum of activity and clinical efficacy of this new formulation are discussed in comparison with currently used antimicrobial agents.

Evaluation of efficacy and safety of ciprofloxacin ophthalmic solution versus chloramphenicol.

The results of this clinical study demonstrate that ciprofloxacin ophthalmic solution 0.3% is as safe and as effective as 0.5% chloramphenicol ophthalmic solution in the treatment of conjunctivitis and blepharitis of bacterial aetiology. Both agents achieved microbiological improvement rates in excess of 90% after 1 week's treatment. On ciprofloxacin 93.5% of patients were judged clinically cured or improved versus 84.6% on chloramphenicol after 1 week. There were no serious adverse affects. One patient in each group suffered drug-related side-effects (chemosis, erythema) which resolved on discontinuation or changing of therapy. Cirpofloxacin is not associated with the rare, but serious, side effect of aplastic anaemia which is associated with chloramphenicol use. On the evidence of this study ciprofloxacin would appear to be an appropriate agent for general use as a topical ophthalmic formulation.

Limbal xanthogranuloma.

Three cases of histologically proven limbal xanthogranuloma are presented. All three cases presented with a yellow raised swelling at the limbus and no other ocular or systemic abnormality. A simple excision of the lesion was carried out in all cases and histological examination revealed features typical of xanthogranuloma. Two patients had a recurrence at the original site, necessitating keratectomy, with insertion of a lamellar graft. We suggest that a primary keratectomy with insertion of a lamellar graft should be performed in cases of limbal xanthogranuloma in order to lessen the risk of recurrence and to provide a better cosmetic result.