104 research outputs found
Corneal wavefront-guided photorefractive keratectomy with mitomycin-C for hyperopia after radial keratotomy: Two-year follow-up
No full textPURPOSE: To assess corneal wavefront-guided photorefractive keratectomy (PRK) to correct hyperopia after radial keratotomy (RK). SETTING: Sadalla Amin Ghanem Eye Hospital, Joinville, Santa Catarina, Brazil. DESIGN: Case series. METHODS: Excimer laser corneal wavefront-guided PRK with intraoperative mitomycin-C (MMC) 0.02% was performed. Main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE), corneal aberrations, and haze. RESULTS: The mean time between RK and PRK in the 61 eyes (39 patients) was 18.8 years +/- 3.8 (SD). Before PRK, the mean SE was +4.17 +/- 1.97 diopters (D); the mean astigmatism, -1.39 +/- 1.04 D; and the mean CDVA, 0.161 +/- 0.137 logMAR. At 24 months, the mean values were 0.14 +/- 0.99 D (P<.001), -1.19 +/- 1.02 D (P=.627), and 0.072 +/- 0.094 logMAR (P<.001), respectively; the mean UDVA was 0.265 +/- 0.196 (P<.001). The UDVA was 20/25 or better in 37.7% of eyes and 20/40 or better in 68.9%. The CDVA improved by 1 or more lines in 62.3% of eyes. Two eyes (3.3%) lost 2 or more lines, 1 due to corneal ectasia. Thirty eyes (49.2%) were within +/- 0.50 D of intended SE and 45 (73.8%) were within +/- 1.00 D. From 6 to 24 months, the mean SE regression was +0.39 D (P<.05). A significant decrease in coma, trefoil, and spherical aberration occurred. Three eyes developed peripheral haze more than grade 1. CONCLUSION: Corneal wavefront-guided PRK with MMC for hyperopia after RK significantly improved UDVA, CDVA, and higher-order corneal aberrations with a low incidence of visually significant corneal haze
Corneal wavefront-guided photorefractive keratectomy (PRK) with adjunctive mitomycin C (MMC) for the treatment of hyperopia after radial keratotomy
No full textOBJETIVO: Avaliar a eficácia, estabilidade, previsibilidade e segurança da ceratectomia fotorrefrativa (PRK) guiada pelas frentes de onda corneana para o tratamento da hipermetropia secundária à ceratotomia radial (CR). MÉTODOS: Foram avaliados prospectivamente 61 olhos de 39 pacientes consecutivos, submetidos a PRK personalizado com o laser Esiris-Schwind. A técnica constou de desepitelização mecânica, fotoablação, e utilização de mitomicina C (MMC) 0,02% por 20 ou 40 segundos. A MMC foi aplicada por 40 segundos em 17 olhos (27,9%) que haviam sido submetidos a ablações mais profundas do que 100 ?m ou apresentavam córneas previamente suturadas. As avaliações pós-operatórias foram realizadas após sete dias, um, seis, 12 e 24 meses. Todos os olhos foram avaliados após um ano e dois anos. RESULTADOS: O intervalo médio entre a CR e o PRK foi de 18,8 anos ± 3,8 (DP); o equivalente esférico (EE) médio antes da ceratotomia radial era -4,10 dioptrias (D) ± 1,44. As medidas prévias ao PRK mostraram EE médio de +4,17 D ± 1,97; astigmatismo médio de -1,39 D ± 1,04; AV com correção (AVcc) média de 0,161 ± 0,137 (logMAR); e curvatura corneana média de 35,85 ± 3,60 D. Os resultados encontrados dois anos após a cirurgia foram: EE médio de 0,14 ± 0,99 D (p < 0,001); astigmatismo médio de -1,19 ± 1,02 D (p = 0,627); AV sem correção (AVsc) média de 0,265 ± 0,196 (p < 0,001); AVcc média de 0,072 ± 0,094 (p < 0,001); e curvatura corneana média de 39,01 ± 3,18 D (p < 0,001). AVsc igual ou melhor a 20/25 foi observada em 38% dos olhos e igual ou melhor a 20/40 em 69%. A AVcc melhorou em 62,3% dos olhos, sendo que 21 olhos (34,4%) melhoraram uma linha e outros 17 olhos (27,9%), duas ou mais linhas. Um olho (1,6%) perdeu duas linhas devido ao astigmatismo irregular ocasionado por opacificação corneana periférica. Outro olho perdeu três linhas pelo desenvolvimento de ectasia corneana entre seis e 24 meses, devido ao alargamento progressivo de uma incisão radial inferior, e foi posteriormente submetido à sutura da incisão. Houve 30 olhos (49,2%) entre ± 0,50 D do EE planejado e 45 (73,8%) entre ± 1,00 D. Entre seis e 24 meses, a regressão média do EE foi de +0,39 D (p < 0,05) e cinco olhos (8,3%) sofreram desvio hipermetrópico > 1,00 D. Ocorreu redução estatisticamente significante do coma (p = 0,001), trefoil (p = 0,008), aberração esférica (p < 0,001), astigmatismo secundário (p = 0,001) e quatrefoil (p < 0,001). Não houve mudança estatisticamente significativa da contagem endotelial (p = 0,161). Dois olhos (3,3%) desenvolveram opacificação corneana periférica grau 2 e um, grau 3. CONCLUSÃO: O PRK personalizado pelas frentes de onda corneana coadjuvado pela MMC foi eficaz, previsível e seguro pelo período de dois anos para a redução da hipermetropia após a CR. No pós-operatório observou-se melhora significativa da AVsc, AVcc e das aberrações corneanas. Constatou-se, entretanto, que a hipermetropia consecutiva à CR continua a progredir após o tratamento com o excimer laser.PURPOSE: To assess the efficacy, stability, predictability and safety of corneal wavefront-guided photorefractive keratectomy (PRK) for correcting hyperopia after radial keratotomy (RK). METHODS: In a prospective study, 61 eyes of 39 consecutive patients were treated with PRK using an Esiris-Schwind excimer laser. Corneal epithelium was mechanically removed, followed by photoablation and use of 0.02% mitomycin C (MMC) for 20 or 40 seconds. MMC was used for 40 seconds in 18 eyes (27.9%) which underwent ablations deeper than 100 micron or had previous corneal sutures. Postoperative evaluations were performed after seven days, six, 12 and 24 months. All patients were followed up for two years. RESULTS: The mean time between RK and PRK was 18.8 years ± 3.8 (SD); mean spherical equivalent (SE) before RK was -4.10 diopters (D) ± 1.44. Before PRK, the mean SE was +4.17 D ± 1.97, mean astigmatism was -1.39 D ± 1.04, the mean best-corrected visual acuity (BCVA) was 0.161 ± 0.137 (logMAR) and the mean corneal curvature was 35.85 ± 3.60 D. At 24 months, mean SE was 0.14 ± 0.99 D (p < 0.001), mean astigmatism was -1.19 ± 1.02 D (p = 0.627), mean UCVA was 0.265 ± 0.196 (p < 0.001), mean BSCVA was 0.072 ± 0.094 (p < 0.001) and the mean corneal curvature was 39.01 ± 3.18 D (p < 0.001). UCVA was 20/25 or better in 38% of eyes and 20/40 or better in 69%. BCVA improved in 62.3% of eyes, with 21 (34.4%) gaining one line and 17 (27.9%), two or more lines. One eye (1.6%) lost two lines due to irregular astigmatism and peripheral haze. Another eye lost three lines due to keratectasia occurring between six and 24 months resulting from widening of an inferior radial incision that was later sutured. Thirty eyes (49.2%) were within ± 0.50 D of intended SE and 45 (73.8%) were within ± 1.00 D. From six to 24 months, the mean SE regression was +0.39 D (p < 0.05) and five eyes (8.3%) had a hyperopic shift > 1.00 D. A significant decrease in coma (p = 0.001), trefoil (p = 0.008), spherical aberration (p < 0.001), secondary astigmatism (p = 0.001) and quatrefoil (p < 0.001) was observed. Endothelial cell counts did not show a statistically significant decrease (p = 0.161). Two eyes (3.3%) developed peripheral haze grade 2 and one, grade 3. CONCLUSION: Corneal wavefront-guided PRK with MMC was effective, predictable and safe after two years for the treatment of hyperopia after RK. A significant improvement in UCVA, BSCVA and corneal aberrations was obtained. However, hyperopic shift after RK continued to progress after excimer laser surgery
Customized Topography-guided Photorefractive Keratectomy With the MEL-70 Platform and Mitomycin C to Correct Hyperopia After Radial Keratotomy
No full textPURPOSE: To evaluate topography-guided photorefractive keratectomy (PRK) for correcting hyperopia and astigmatism after radial keratotomy (RK). METHODS., Prospective study of 12 consecutive patients (19 eyes) who were treated with topography-guided PRK with 0.02% mitomycin C using an Asclepion-Meditec MEL-70 excimer laser with a 9.5-mm ablation zone. All eyes were operated by the same surgeon and followed for 1 year. RESULTS: Thirteen eyes had complete epithelialization by day 7 and all eyes by day 10. At 1 year, uncorrected visual acuity was 20/25 or better in 42.1% of eyes and 20/40 or better in 68.4%. Preoperative mean spherical equivalent refraction was +3.80 +/- 2.47 diopters (D) and +0.24 +/- 2.36 D (P <.001) 1 year postoperative, with 47.4% of eyes being within +/- 1.00 D and 73.7% within +/- 2.00 D. Preoperative mean cylinder was -2.30 +/- 1.41 D and -0.62 +/- 0.73 D (P <.1001) 1 year postoperative. At 1 year, 68.4% of eyes gained at least 1 line of best-spectacle corrected visual acuity, 36.8% gained more than 1 line, and only 2 eyes lost 1 line (one due to corneal haze). Three eyes developed central haze. Mean regression from 6 to 12 months in these 3 eyes was +1.83 D and in the remaining 16 eyes was -0.50 D. CONCLUSIONS: Topography-guided PRK with mitomycin C was safe and reasonably effective for the treatment of hyperopia after RK [J Refract Surg. 2008;24:911-922.
Photo of E.L. Doctorow (left), and Carol C. Harter (right) at Homer and Langley in 2009 at Black Mountain Institute.
No full textOn November 10, E.L. Doctorow —the renowned author of Billy Bathgate, Ragtime, and The March — read from his newest novel, Homer & Langley. Doctorow served as UNLV\u27s 2009 Elias Ghanem Chair in Creative Writing.https://oasis.library.unlv.edu/blackmountain_images/1011/thumbnail.jp
Political regimes, trade, and labor policies in developing countries
No full textWhat, if any, is the link between labor market policies that benefit insiders - for example, regulations guaranteeing high minimum wages and strict job security - and political regimes. Is it true that in a democracy outsiders vote and impose limits on what insiders can achieve, whereas in a dictatorship the government need worry only about insiders who have real power? Or are democratic governments more likely to succumb to trade union pressure and use labor policies to give them special privileges? To test these competing hypotheses, the authors designed a two-sector political economy model that demonstrates that labor market distortions depend directly on the trade regime: the more open the trade regime, the fewer distortions in the labor market. They use cross-country regressions to test the relationship between political and civil liberties and trade and labor policies. Using data for 90 developing countries, they apply existing indices of openness and political freedom and two different constructed measures of labor market distortion. Their conclusions, based on the regression results: authoritarian systems that repress labor are more likely than democratic systems to adopt inefficient labor policies inimical to development.Economic Theory&Research,Environmental Economics&Policies,Labor Policies,Health Economics&Finance,Banks&Banking Reform,Environmental Economics&Policies,Health Economics&Finance,Banks&Banking Reform,Labor Standards,Economic Theory&Research
Photo of E.L. Doctorow (left), and Carol C. Harter (right) at Homer and Langley in 2009 at Black Mountain Institute.
No full textOn November 10, E.L. Doctorow —the renowned author of Billy Bathgate, Ragtime, and The March — read from his newest novel, Homer & Langley. Doctorow served as UNLV\u27s 2009 Elias Ghanem Chair in Creative Writing.https://oasis.library.unlv.edu/blackmountain_images/1011/thumbnail.jp
Microeconomic distortions : static losses and their effect on the efficiency of investment
No full textIn the past decade the developing countries have tried much harder to achieve macroeconomic stability than they have to eliminate inefficiencies from microeconomic distortions. The author has pursued a relatively new line of inquiry in examining measurement of the social income losses induced by the reduction of the investment efficiency caused by trade distortions. Empirical findings of the study suggest a strong negative effect of trade distortions on the social efficiency of investment. The social income losses caused by the reduced investment efficiency are considerable. Countries that have a moderate investment ratio (about 20 percent of GDP) can experience social income losses in excess of 18 percent in 30 years, if tariffs are about 50 percent. This study confirms earlier findings about the relatively modest efficiency losses caused by the independent effects of specific distortions. The author alsofound a significant synergistic effect when trade and wage distortions coexist and lead to larger efficiency losses. The key issue is the combination of price distortions favoring capital-intensive activity with wage distortions that cause unemployment and underemployment. This pattern is pervasive in developing countries.Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Economic Growth,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT
Safety of photorefractive keratectomy with mitomycin-C for the treatment of hyperopia after radial keratotomy
No full textOBJETIVO: Analisar a segurança da ceratectomia fotorrefrativa (PRK) com mitomicina-C (MMC) em olhos com hipermetropia consecutiva à ceratotomia radial. MÉTODOS: Foram avaliados prospectivamente 60 olhos de 36 pacientes consecutivos, submetidos à ceratectomia fotorrefrativa personalizada pela frente de onda corneana com o laser Esiris Schwind. Realizaram-se desepitelização mecânica, seguida da fotoabla ção, e utilização de MMC 0,02% por 20 ou 40 segundos. Em 16 olhos (26,7%) a MMC foi aplicada por 40 segundos. Estes foram submetidos a ablações mais profundas do que 100 micra ou apresentavam córneas submetidas a suturas prévias. Os pacientes foram acompanhados por um ano. RESULTADOS: O equivalente esférico (EE) médio antes do PRK era +4,27 D ± 2,18 e a acuidade visual corrigida (AVcc) média era 0,174 ± 0,139 (logMAR). O EE médio programado no laser foi +4,74 D ± 2,11, resultando em uma profundidade de ablação de 78 ± 28 µm (de 33 a 148). Não foram observadas complicações intraoperatórias. Após um ano observaram-se: EE médio de + 0,04 D ± 1,03 (p<0,001) e AVcc de 0,079 ± 0,105 (p<0,001). Observou-se melhora de duas ou mais linhas de AVcc em 20 olhos (33,3%) e somente 1 olho (1,7%) perdeu duas linhas. A análise de correlação mostrou que a melhora da AVcc foi inversa mente correlacionada à AVcc pré-operatória (r=-0,694; p<0,001). ''Haze'' periférico grau 2 ou 3 foi observado em cinco olhos e ''haze'' central discreto, em um olho. Não houve correlação significativa do ''haze'' central ou periférico com o número de incisões radiais, com a profun didade da fotoablação ou com a AVcc pós-operatória. A contagem endotelial média no pré-operatório foi de 2.681± 455 cel/mm2 e após 1 ano foi de 2.481 ± 378 cel/mm2 (p=0,124). Um olho desenvolveu ectasia corneana, devido ao alargamento progressivo de uma incisão radial inferior, e foi submetido à sutura da incisão. CONCLUSÃO: O PRK com MMC mostrou-se seguro após um ano para a redução da hipermetropia secundária a ceratotomia radial. Observou-se melhora significativa da AVcc, com pequena incidência de ''haze'' e de outras complicações.PURPOSE: To evaluate the safety of photorefractive keratectomy (PRK) with mitomycin-C (MMC) in eyes with hyperopia after radial keratotomy. METHODS: Sixty eyes of 36 consecutive patients treated with corneal wavefront-guided PRK using an Esiris-Schwind excimer laser were prospectively evaluated. Corneal epithelium was mechanically removed, followed by photoablation and use of 0.02% MMC for 20 or 40 seconds. In 16 eyes (26.7%), MMC was applied for 40 seconds. These eyes underwent ablations deeper than 100 micron or had previous corneal sutures. Patients were followedup for 12 months. RESULTS: The mean spherical equivalent (SE) before PRK was +4.27 D ± 2.18, and the mean bestcorrected visual acuity (BCVA) was 0.174 ± 0.139 (logMAR). The planned laser SE correction was +4.74 D ± 2.11, resulting in an ablation depth of 78 ± 28 µm (from 33 to 148). No intraoperative complications were observed. At one year, mean SE was +0.04 D ± 1.03 (p<0.001) and mean BCVA was 0.079 ± 0.105 (p<0.001). There was a gain of 2 or more lines of BCVA in 20 eyes (33.3%) and only one eye (1.7%) lost 2 lines. Correlation analysis showed that the improvement in BCVA was inversely related to preoperative BCVA (r=-0.694; p<0.001). Five eyes developed peripheral haze grade 2 or 3 and one eye had central trace haze. No significant correlation was found between central or peripheral haze and the number of radial incisions, depth of the ablation or postoperative BCVA. Mean preoperative endothelial cell count was 2,681 ± 455 cel/ mm² and after one year was 2,481 ± 378 cel/mm² (p=0.124). One eye developed keratectasia due to the progressive widening of an inferior radial incision, which was later sutured. CONCLUSION: PRK with MMC was safe after one year of follow-up for the reduction of hyperopia after radial keratotomy. A major improvement in BCVA was obtained with a small incidence of haze and other complications
The rise of securities markets : what can government do?
No full textUsing U.S. securities markets as a case history, the author explores the role securities markets play in economic development, how they emerge, and how regulation can make them more effective. Why the United States? Two centuries ago, it was a small undeveloped country with serious financial problems. It confronted those problems and, guided by Alexander Hamilton, creatively reformed its financial system, which then became a foundation of the U.S. economic infrastructure and a bulwark for long-term growth. When Hamilton's program established public credit and securitiesmarkets in the 1790s, U.S. citizens were immediately able to borrow from older, richer countries. U.S. wealth then increased until, by the end of the nineteenth century, U.S. residents began to lend and invest more abroad than they borrowed. During the 1820s and 1830s, the United States (usually state governments) borrowed large sums from foreign investors to build roads, canals, and early railroads, to make other transportation improvements, and to capitalize state banks. From the 1830s to the end of the century, still larger sums from overseas went into private U.S. railway companies that provided cheap transcontinental transportation. Most of this borrowing took the form of state and corporate bond sales to overseas investors. The pristine U.S. government credit established by Hamilton thus rubbed off on U.S. state and corporate debt. The British stock market did better than the U.S. market until the United States adopted security-market regulation (including disclosuire rules) under the SEC. Then the U.S. market became a world leader. The U.S. stock market developed more slowly than the bond market, but it both aided and benefited from foreign investment in U.S. bonds. Foreign investors preferred debt securities to equities, yet equities create a safety margin for bondholders who, because of this margin, are more willing to purchase and hold bonds. Foreign investors preferred bonds; U.S. investors, after exporting bonds, held more stocks than bonds at home. Why? Because good stock markets permit the conversion of equity securities into cash.Environmental Economics&Policies,Payment Systems&Infrastructure,Financial Intermediation,International Terrorism&Counterterrorism,Economic Theory&Research,Housing Finance,Insurance&Risk Mitigation,Financial Intermediation,Environmental Economics&Policies,Economic Theory&Research
Corneal wavefront-guided photorefractive keratectomy with mitomycin-C for consecutive hyperopia after radial keratotomy
No full textOBJETIVO: Avaliar a eficácia, previsibilidade e estabilidade da ceratectomia fotorrefrativa (PRK) guiada pela frente de onda corneana para o tratamento da hipermetropia secundária à ceratotomia radial. MÉTODOS: Este estudo prospectivo analisou 60 olhos de 36 pacientes consecutivos, submetidos a PRK personalizado com o laser Esiris-Schwind. A técnica constou de desepitelização mecânica, fotoablação e utilização de mitomicina-C 0,02%. Os pacientes foram acompanhados por 12 meses. RESULTADOS: O intervalo médio entre a ceratotomia radial e o PRK foi de 18,4 anos ± 3,8 (DP); o equivalente esférico (EE) médio antes da ceratotomia radial era -4,35 dioptrias (D) ± 1,55. As medidas prévias ao PRK mostraram grau esférico médio de +5,00 D ± 2,28, astigmatismo médio de -1,47 D ± 1,06, EE médio de +4,27 D ± 2,18 e AV corrigida (AVcc) média de 0,174 ± 0,139 (logMAR). O EE médio programado no laser foi +4,74 D ± 2,11. Os resultados encontrados um ano após a cirurgia foram: EE médio de +0,04 D ± 1,03 (P<0,001), astigmatismo médio de -1,03 ± 0,75 D (P=0,015), AV média sem correção de 0,265 ± 0,197 e AVcc de 0,079 ± 0,105 (P<0,001). A AVcc mostrou ganho médio de uma linha; 20 olhos (33,3%) melhoraram duas ou mais linhas e somente um olho perdeu duas linhas. Ocorreu redução estatisticamente significante do coma (P=0,002), trefoil (P=0,004), aberração esférica (P<0,001) e quatrefoil (P=0,002). Houve 48 olhos (80%) entre ± 1,00 D do EE planejado. A regressão média entre seis e 12 meses foi de +0,17 ± 0,67 D. CONCLUSÃO: O PRK personalizado pela frente de onda corneana foi eficaz, previsível e estável pelo período de um ano para a redução da hipermetropia após a ceratotomia radial. No pós-operatório, observou-se melhora significativa da AVsc, AVcc e das aberrações corneanas. Número do ClinicalTrials.gov:NCT00917657PURPOSE: To assess the efficacy, predictability and stability of corneal wavefront-guided photorefractive keratectomy (PRK) for correcting hyperopia and astigmatism after radial keratotomy. METHODS: In a prospective study, 60 eyes of 36 consecutive patients were treated with corneal wavefront-guided PRK with 0.02% mitomycin-C using an Esiris-Schwind excimer laser. Corneal epithelium was mechanically removed. All patients were followed-up for 12 months. RESULTS: The mean time between radial keratotomy and PRK was 18.4 years ± 3.8 (SD); mean spherical equivalent (SE) before radial keratotomy was -4.35 diopters (D) ± 1.55. Before PRK, the mean sphere was +5.00 D ± 2.28, mean astigmatism was - 1.47 D ± 1.06, mean SE was +4.27 D ± 2.18, and the mean best-corrected visual acuity (BCVA) was 0.174 ± 0.139 (logMAR). The planned laser SE correction was +4.74 D ± 2.11. No intraoperative complications were noted. At 12 months, mean SE was +0.04 D ± 1.03 (P<0.001), mean astigmatism was -1.03 ± 0.75 D (P=0.015), mean UCVA was 0.265 ± 0.197, and mean BCVA was 0.079 ± 0.105 (P<0.001). There was a mean gain of 1 line of BCVA and 20 eyes (33.3%) gained 2 or more lines. Only one eye lost 2 lines. A significant decrease in coma (P=0.002), trefoil (P=0.004), spherical aberration (P<0.001) and quatrefoil (P=0.002) was observed. Forty eight eyes (80%) were within ± 1.0 D of intended SE. Mean regression from 6 to 12 months was +0.17 ± 0.67 D. CONCLUSION: Corneal wavefront-guided PRK was effective, predictable and stable after one year of follow-up for the treatment of hyperopia after radial keratotomy. A significant improvement in UCVA, BCVA and corneal aberrations was obtained. ClinicalTrials.gov Identifier: NCT0091765
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