Navegando por Palavras-chave "Refractive errors"

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    Achados oculares em crianças de zero a seis anos de idade, residentes na cidade de São Caetano do Sul, SP
    (Conselho Brasileiro de Oftalmologia, 2003-12-01) Beer, Sandra Maria Canelas [UNIFESP]; Scarpi, Marinho Jorge [UNIFESP]; Minello, Antonieta Antunes [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To establish the prevalence of refractive errors, strabismus, amblyopia and anisometropia, among children in a population, using two methods of screening (at school and at the National Polio Vaccination Day). METHODS: We examined 2,640 children, between 0 and 6 years of age. The children, residents of the city São Caetano do Sul, were divided into two groups (A and B). Group A: 476 children, with an age range of a few months to 6 years, had their eyes examined by 10 ophthalmologists and 11 ophthalmology technicians, during the National Polio Vaccination Day (June 20,1998). Group B: 2,164 children attending municipal schools (EMEIs and EMIs), between 4 and 6 years of age, who had their eyes examined by two ophthalmologists during the year of 1998. RESULTS: In group A, the prevalence of strabismus was 3.36% and that of anisometropia was 1.26%. The most common type of refractive error was hypermetropia £ 2D and 14.11% required optical prescription. In group B, the prevalence of strabismus was 1.43%. In the group who failed in the screening, the prevalence of amblyopia was 1.39% and that of anisometropia was 2.8%. The most common type of refractive error found was hypermetropic astigmatism and 56.48% required optical prescription. CONCLUSION: The prevalence of the ocular findings in children in São Caetano do Sul, although being a city with a privileged socioeconomic profile, is similar to that reported in the literature. Ophthalmic examination on National Polio Vaccination Day showed to be an efficient screening tool.
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    Adaptação de lentes de contato após cirurgia refrativa
    (Conselho Brasileiro de Oftalmologia, 2005-02-01) Renesto, Adimara Da Candelária [UNIFESP]; Lipener, César [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To evaluate the fitting and use of contact lens in patients submitted to refractive surgery. METHODS: This was a retrospective study in 53 patients submitted to refractive surgery who later started to use contact lens, from 1999 to 2003. The parameters were: previous ametropia, refractive surgery procedure, ametropia after surgery, postoperative spherical equivalent, postoperative keratometry, base curve of fitted contact lens, contact lens design, final visual acuity with spectacles after surgery, final visual acuity with contact lens, complications and the reason for stopping the use. The follow-up of patients ranged from 1 month to 84 months (average of 42,5 months). RESULTS: Of 53 evaluated patients, 19 patients had undergone LASIK (Laser Assisted in Situ Keratomileusis), 29 patients had undergone RK (radial keratotomy), 4 patients had undergone PRK (photorefractive keratectomy) and in one patient it was not possible to know which surgery was performed. 61.29% of the patients (57 eyes of a total of 93 eyes) were fitted with rigid gas-permeable lenses. There was an improvement of visual acuity in 60.21% of the cases (VA>20/40), with few complications. CONCLUSION: Due to the great number of performed refractive surgery, an increase in the number of patients unhappy with the postoperative result is expected, and for these patients, many times the use of contact lens is the best option. The fitting of contact lenses after refractive surgery demands knowledge, dedication and has good results principally regarding better visual acuity.
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    Análise comparativa da refração automática objetiva e refração clínica
    (Conselho Brasileiro de Oftalmologia, 2001-02-01) Uras, Ricardo [UNIFESP]; Belfort, Rubens Junior [UNIFESP]; Hofling-Lima, Ana Luisa [UNIFESP]; Martins, Elisabeth Nogueira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Purpose: This study was designed to determine if lens prescription can be based solely on automated objective refraction. Methods: All patients were interviewed and underwent an ophthalmologic examination including clinical refraction with classical non-automated objective and subjective procedures (gold standard). Afterwards the automated objective refraction was performed using the automatic keratorefractor TOPCON 3000. Results: 1,001 eyes of 504 patients were studied. 45.2% were male patients and the mean age was 36.6 years. There was an overall concordance between clinical refraction and the automated objective refraction in 66.7% of the patients. The concordance of a spherical value, not considering variations of -0.50 to +0.50 SD was, approximately 90%. In simple hyperopic/myopic astigmatic eyes the concordance was 27.6%, in eyes with compound hyperopic/myopic astigmatism the concordance was 97.7%. Cycloplegia did not significantly affect this concordance. There was no significant difference regarding the axis of astigmatic eyes when using both techniques. Conclusion: Automated objective refraction is an useful tool in clinical refraction but clinical data should also be considered and the final lens prescription should never be based solely on the automated examination.
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    Análise comparativa entre a refração clínica subjetiva e a automatizada obtida por sensor de frentes de onda
    (Conselho Brasileiro de Oftalmologia, 2007-08-01) Freitas, Wilson de [UNIFESP]; Melo Júnior, Luiz Alberto Soares [UNIFESP]; Schor, Paulo [UNIFESP]; Campos, Mauro Silveira de Queiroz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To evaluate and compare refractive errors obtained through clinical subjective and automatized wavefront refraction analyses in eyes under cycloplegia. METHODS: Prospective study of 147 patients, 279 eyes, undergoing preoperative examination for refractive surgery. Clinical subjective refraction was performed first followed by wavefront refraction. Results on astigmatism obtained from refraction were decomposed in power vectors for statistical analyses. Data were first analyzed in one eye and then in both eyes. RESULTS: The mean difference between clinical subjective refraction and automatized wavefront refraction on cycloplegic eyes was of -0.19 SD combined with -0.06 CD in the 15º axis for data in one eye, and -0.17 SD combined with -0.05 CD in the 3º axis for data in both eyes of the same patient. CONCLUSION: In the present study clinical subjective refraction and automatized wavefront refraction under cycloplegia had similar numerical values.
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    Análise laboratorial das ceratites infecciosas secundárias à cirurgia refrativa
    (Conselho Brasileiro de Oftalmologia, 2005-06-01) Leal, Fernando [UNIFESP]; Hofling-Lima, Ana Luisa [UNIFESP]; Freitas, Denise de [UNIFESP]; Campos, Mauro Silveira de Queiroz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To describe the laboratory findings in patients with infectious keratitis, who underwent refractive surgery, correlating the surgical procedure and the time of infection manifestation, and the results of culture and smears. METHODS: The previous samples were obtained from patients submitted to radial keratotomy (RK), photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) at the Ophthalmology Department of UNIFESP. The infections were classified as early, when they occurred up to 30 days after the surgery, and late when diagnosed after 30 days. RESULTS: In 93 samples, 39 (42%) came from patients submitted to radial keratotomy, 14 (36%) being early infections and 25 (64%) late; 38 (41%) of LASIK, 21 (55%) being early and 17 (45%) late; 16 (17%) of photorefractive keratectomy, 10 (62.5%) being early and 6 (37.5%) late. Eighty-six samples were submitted to culture and smears for bacteria, 43 cultures (50%) and 43 smears (50%) were positive. Seventy-two samples were submitted to culture and smears for fungi, 2 cultures (3%) and 4 smears (6%) were positive. CONCLUSION: The agreement between culture and smear results was 80.2%; regarding the type of surgery there was no statistically significant relationship between time of onset of infection and surgery.
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    Avaliação do impacto da cirurgia refrativa na qualidade de vida por meio do questionário NEI-RQL (National Eye Institute Refractive Error Quality of Life)
    (Conselho Brasileiro de Oftalmologia, 2005-12-01) Nunes, Larissa Madeira [UNIFESP]; Schor, Paulo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To assess the impact of refractive surgery on quality of life using the National Eye Institute Refractive Error Quality of Life instrument (NEI-RQL) and to evaluate the responsiveness of our Portuguese version of the NEI-RQL instrument to surgical correction of refractive error. METHODS: In this prospective study, the NEI-RQL, a 42-item questionnaire with 13 scales, was self-administered by 96 patients of the Federal University of São Paulo - UNIFESP, between March 2002 and April 2003, before and after undergoing surgical correction of refractive error. An overall scale score was determined by calculating the mean of the 13 scale scores. Differences between preoperative and postoperative NEI-RQL scores were examined. Responsiveness was assessed by calculating the size of effect for each scale of the instrument. RESULTS: Refractive surgery was associated with statistically significant improvements in scores for all the scales of the NEI-RQL. The NEI-RQL has shown to be responsive to surgical correction of refractive error, and the calculated effect sizes ranged from 0.4 (glare) to 4.19 (expectations). CONCLUSIONS: The NEI-RQL is highly responsive to changes in vision-related quality of life resulting from keratorefractive surgery. We observed improvements in all the scales of the NEI-RQL, after surgery.
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    Biometria ocular, erro refrativo e sua relação com a estatura, idade, sexo e escolaridade em adultos brasileiros
    (Conselho Brasileiro de Oftalmologia, 2007-06-01) Pereira, Graziela Campanelli [UNIFESP]; Allemann, Norma [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To assess ocular biometric parameters and refractive error in Brazilian adults and their relationship with height, age, gender and years of formal education. METHODS: Cross-sectional study that assessed 173 subjects by keratometry, echobiometry, refraction and measurement of body height. The statistical analysis was performed using Pearson's coefficient and a regression model was constructed. RESULTS: The correlations found were: each 10 cm - increase in height was related to a 0.32 mm longer axial length, 0.07 mm deeper anterior chamber, 0.26 mm deeper vitreous chamber and 0.50 D flatter keratometry. Each 10-year increase in age, related to a 0.15 mm smaller axial length, 0.25 mm thicker lens, 0.21 mm shallower vitreous chamber and 0.23 D more positive spherical equivalent. Each 10-year increase in education related to a 0.74 D more negative spherical equivalent. Gender did not influence the analyzed biometric parameters. Equations referring to biometric parameters and spherical equivalent were formulated. CONCLUSIONS: Positive correlations were found between: axial length and height; anterior chamber and vitreous cavity depth with height; lens thickness with age; keratometry with height; and spherical equivalent with age. Negative correlations were found between: anterior chamber and vitreous cavity depth with age; spherical equivalent and years of formal education.
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    Cirurgia refrativa: quem precisa de tratamento personalizado?
    (Conselho Brasileiro de Oftalmologia, 2003-01-01) Chamon, Wallace [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Journal of Refractive Surgery
    Refractive surgery is facing an important period of its evolution. Day by day we are getting used to terms such as: wave front, customized ablation, supervision, aberrations, etc. What will be the future of all these technologies? It is important to understand that all these terms are based on some unquestionable facts. In this manuscript the following subjects were considered: 1. Improvement of visual performance when correcting optical aberrations, 2. The change in the concept of physiologic optics, 3. The relationship between refraction and refractive map 4. Visual benefit, 5. Chromatic and spherical aberrations
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    Clinical evaluation of reprocessed blades in LASIK
    (Conselho Brasileiro de Oftalmologia, 2008-04-01) Mallmann, Felipe [UNIFESP]; Murata, Celina [UNIFESP]; Yamazaki, Ester Sakae [UNIFESP]; Campos, Mauro Silveira de Queiroz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To evaluate outcome and complications in LASIK with reprocessed blades. METHODS: Retrospective analysis of patients' charts submitted to complete custom LASIK from January 2004 to June 2005. Inclusion criteria comprised surgical description of blade use and minimum follow-up of 1 month. The blade was reprocessed following a clinic protocol, from 1 to 3 times (reprocessed group) and results compared with patients that underwent LASIK with first-use blades (first-use group). RESULTS: Two hundred fifty-one eyes of 135 patients were analyzed (spherical equivalent of -3.69 (D). There was no statistical differences between first-use group and reprocessed blade group regarding intraoperative (5.5% vs 8.8%), early (50.5% vs 49.5%) and late complications (33% vs 27.5%), respectively. Uncorrected visual acuity > 20/20 (68.1% vs 66.9%), aberrometry analysis (total RMS: 0.62 vs 0.64 µm) and safety (85.7% vs 83.1%) were similar between groups (p>0.05). CONCLUSION: Reprocessed blades following rigid sterilization protocol may have similar outcomes and complications rates in LASIK surgery compared to first-use blades.
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    Clinical results in phacoemulsification using the SRK/T formula
    (Conselho Brasileiro de Oftalmologia, 2009-04-01) Lagrasta, Juliana Marques de Souza [UNIFESP]; Allemann, Norma [UNIFESP]; Scapucin, Luciana [UNIFESP]; Moeller, Cecilia Tobias de Aguiar [UNIFESP]; Ohkawara, Lilian Emi [UNIFESP]; Melo Junior, Luiz Alberto Soares [UNIFESP]; Soriano, Eduardo Sone [UNIFESP]; Casanova, Fabio Henrique [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To evaluate the prediction of refraction using the SRK/T formula for intraocular lens (IOL) calculation in eyes with medium axial length after phacoemulsification. METHODS: This prospective study enrolled 33 eyes with nuclear cataract that underwent phacoemulsification. All procedures were performed by one surgeon with the intraocular lens placed within the capsular bag. The same technician who was unaware of the purpose of the study made all the measurements. The achieved refractive error one month after surgery was compared to the predicted postoperative refractive error by the SRK/T formula. RESULTS: The ocular axial length varied between 22.2 mm and 24.5 mm. The mean predicted refraction was -0.431 ± 0.181 D and the mean achieved postoperative spherical equivalent was -0.220 ± 0.732 D. Eighteen eyes (55%) had a refractive error between ± 0.50 D and thirty eyes (91%) between ± 1.00 D of the predicted refraction. There was a tendency toward hyperopic shift (mean ± SD: 0.211 ± 0.708 D, p=0.009). CONCLUSION: The SRK/T formula demonstrated a satisfactory accuracy to calculate the error of refraction in eyes with medium axial length.
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    Comparação entre qualidade de visão auto-relatada e acuidade visual em população idosa de baixa renda na cidade de São Paulo
    (Conselho Brasileiro de Oftalmologia, 2006-02-01) Cinoto, Rafael Werneck [UNIFESP]; Berezovsky, Adriana [UNIFESP]; Belfort, Rubens Junior [UNIFESP]; Salomão, Solange Rios [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: Self-reported visual function questionnaires are becoming more common in clinical research. The purpose of this study is to evaluate and correlate self-reported visual function assessed by a visual function questionnaire with visual acuity. METHODS: 806 patients aged 60 years and older, who were included in an epidemiological eye study, were interviewed and present visual acuity for near and distance was taken; they also answered a visual function questionnaire. RESULTS: Weak correlations were found between self-reported visual function assessed by a visual function questionnaire and visual acuities for both distance and near. CONCLUSION: Self-reported visual function assessed by a visual function questionnaire did not correspond to visual acuity, nevertheless it can provide important information to the ophthalmologist.
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    Desempenho visual de lentes de contato gelatinosas de diferentes tipos baseado na análise de frentes de onda
    (Conselho Brasileiro de Oftalmologia, 2008-12-01) Gatti, Roberta Fagnani [UNIFESP]; Lipener, César [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To evaluate the visual performance by wavefront analyses of six different kinds of soft contact lenses: Cooperflex® (Cooper Vision), Frequency® 55 Aspheric (Cooper Vision), World Vision FW® (World Vision), Pure Vision® (Bausch & Lomb), Focus® Monthly (Ciba Vision) and Focus® Choice AB (Ciba Vision). METHODS: A prospective study was performed with 130 eyes of 71 myopic or hyperopic patients with astigmatism until 1.50 diopter and best corrected visual acuity 20/20 or better. The patients first underwent ophthalmic examination and then wavefront analyses without visual correction and wearing one of the different contact lenses included in the study. The patients were divided into six similar groups, each one tested with one of the six lenses included in the study. RESULTS: Changes at the values of high order aberrations were verified during the use of contact lenses. In 78 (60%) of the 130 analyzed eyes an increase at the RMS (rooth mean square) values during the use of contact lens was detected. All types of analyzed contact lenses showed an increase of coma aberrations due to contact lens use. Frequency® Aspheric and Cooperflex® had the best visual performance in relation to coma. There was a decrease in the medium value of spherical aberrations during the use of contact lenses, higher in myopic patients than in the hyperopic. There was an increase in the other high order aberrations (that exclude the third order coma and fourth order spherical aberration) characterized by the component others on the aberrometry examination. Focus® Choice AB had the best visual performance of this component. CONCLUSION: The use of soft contact lenses modifies the performance of high order aberrations, showing an increase of the medium values of asymmetric Zernike aberrations. This was not observed for symmetric spherical aberrations. No statistically significant differences were observed between the performance of six kinds of lenses included at this study.
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    Distúrbios visuais e desequilíbrios posturais: uma revisão de escopo
    (Universidade Federal de São Paulo, 2022-01-27) Tseng, Tereza [UNIFESP]; Cockell, Fernanda Flávia [UNIFESP]; Ostolin, Thatiane Lopes Valentim Di Paschoale [UNIFESP]; http://lattes.cnpq.br/4675570734968007; http://lattes.cnpq.br/9338283259338237; http://lattes.cnpq.br/6999388140297755; Universidade Federal de São Paulo (UNIFESP)
    Os períodos de transição entre a infância e a adolescência, no decorrer do processo de desenvolvimento e produção social do corpo apresentam-se como fatores complexos que podem contribuir para o aparecimento de problemas posturais e visuais. Os distúrbios visuais, posturais e as dores crônicas associadas a eles tornaram-se problemas de saúde pública devido ao seu ônus econômico e social. Além de altamente prevalentes na fase infanto-juvenil, tais distúrbios são responsáveis pela redução da qualidade de vida, bem como pelo risco aumentado de evoluir para escoliose e cegueira quando nãotratados e, por isso, carecem de estratégias preventivas. Com o objetivo de identificar a literatura existente e as principais lacunas relacionadas a este tema, realizamos uma revisão de escopo com os termos “Child”, “Adolescent”, “Vision Disorders” e “Posture” nas seguintes bases de dados: Scielo, PMC, BIREME, PEDro e Cochrane, assim como na literatura cinzenta: CAPES e Open Grey. Foram encontrados no total 16698 citações referentes à comprometimentos visuais e posturais. Todavia, apenas foram selecionados 51 estudos publicados nos anos de 1982 a 2021. Dentre eles, houve 48 estudos primários, subdivididos em observacionais (n= 42) e experimentais (n= 6), e 3 artigos secundários. Os participantes desses estudos foram principalmente crianças e adolescentes que apresentavam distúrbios visuais (erros refracionais, nistagmo e estrabismo) ou escoliose idiopática e não foram relatados os possíveis comorbidades associados. As iniquidades em saúde não foram abordadas, exceto sexo. As possíveis relações foram descritas, sobretudo, por meio das avaliações estáticas da postura cervical, métodos de Cobb e testes de movimentos oculares. E foi encontrado que os erros de refração podem refletir no desalinhamento da cabeça, bem como o sistema proprioceptivo do cervical alterado devido às curvaturas das colunas podem levar à disfunção oculomotora. No entanto, as intervenções orientadas para a saúde postural nem sempre culminam efeitos positivos na saúde visual. Ademais, não se sabe da eficácia do tratamento ocular no controle postural pela falta de estudos.
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    Dysfunction in the fellow eyes of strabismic and anisometropic amblyopic children assessed by visually evoked potentials
    (Consel Brasil Oftalmologia, 2016) Andrade, Eric Pinheiro [UNIFESP]; Berezovsky, Adriana [UNIFESP]; Sacai, Paula Yuri [UNIFESP]; Pereira, Josenilson Martins [UNIFESP]; Rocha, Daniel Martins [UNIFESP]; Salomao, Solange Rios [UNIFESP]
    Purpose: To evaluate visual acuity and transient pattern reversal (PR) visual evoked potentials (VEPs) in the fellow eyes of children with strabismic and/or anisometropic amblyopia. Methods: Children diagnosed with strabismic and/or anisometropic amblyopia were recruited for electrophysiological assessment by VEPs. Monocular grating and optotype acuity were measured using sweep-VEPs and an Early Treatment Diabetic Retinopathy Study chart, respectively. During the same visit, transient PR-VEPs of each eye were recorded using stimuli subtending with a visual angle of 60', 15', and 7.5'. Parameters of amplitude (in mu V) and latency (in ms) were determined from VEP recordings. Results: A group of 40 strabismic and/or anisometropic amblyopic children (22 females: 55%, mean age = 8.7 +/- 2.2 years, median = 8 years) was examined. A control group of 19 healthy children (13 females: 68.4%, mean age = 8.2 +/- 2.6 years, median = 8 years) was also included. The fellow eyes of all amblyopes had significantly worse optotype acuity (p = 0.021) than the control group, regardless of whether they were strabismic (p = 0.040) or anisometropic (p = 0.048). Overall, grating acuity was significantly worse in the fellow eyes of amblyopes (p = 0.016) than in healthy controls. Statistically prolonged latency for visual angles of 15' and 7.5' (p = 0.018 and 0.002, respectively) was found in the strabismic group when compared with the control group. For the smaller visual stimulus (7.5'), statistically prolonged latency was found among all fellow eyes of amblyopic children (p< 0.001). Conclusions: The fellow eyes of amblyopic children showed worse optotype and grating acuity, with subtle abnormalities in the PR-VEP detected as prolonged latencies for smaller size stimuli when compared with eyes of healthy children. These findings show the deleterious effects of amblyopia in several distinct visual functions, mainly those related to spatial vision.
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    Estudo comparativo entre duas plataformas para realização de Lasik personalizado para correção de miopia e astigmatismo: Alcon CustomCornea® versus Bausch & Lomb Zyoptix®
    (Conselho Brasileiro de Oftalmologia, 2009-08-01) Barreiro, Telma Pereira; Forseto, Adriana dos Santos [UNIFESP]; Pinto, Lucila Ferreira Leite; Francesconi, Claudia Maria; Nosé, Walton [UNIFESP]; Eye Clinic; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To compare the visual and clinical outcomes of Wavefront-guided laser in situ keratomileusis (Lasik) with Alcon CustomCornea® and Zyoptix® systems. METHODS: A prospective, randomized, masked and bilateral study was conducted. Fifty patients with preoperative spherical equivalent ranging from -1.00 to -6.50 D were enrolled for customized ablation in both eyes. All of them were submitted to Lasik CustomCornea® treatment in one eye and Zyoptix® in the other eye. Uncorrected visual acuity, best correct visual acuity (BCVA), manifest refraction, wavefront measurements, and contrast sensitivity testing were performed preoperatively and postoperatively at 1, 3 and 6 months. RESULTS: Preoperatively manifest refractive spherical equivalent was -3.29 ± 1.56 D in the CustomCornea® group and -3.22 ± 1.50 D in the Zyoptix® group. At 6 months, 86% of CustomCornea® eyes and 70% of Zyoptix® eyes had UCVA > 20/20. One hundred percent of the CustomCornea® group and 88% of the eyes in the Zyoptix® were within 0.50 D of emmetropia. In both groups, the contrast sensitivity improved. Spherical aberration increased in both groups, with the CustomCornea® group showing lower levels (p<0,001). CONCLUSION: There were no differences between the systems according to safety and effectiveness. The Zyoptix® platform showed greater spherical aberration.
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    Frentes de ondas (wavefronts) e limites da visão humana Parte 1: fundamentos
    (Conselho Brasileiro de Oftalmologia, 2002-12-01) Jankov, Mirko [UNIFESP]; Mrochen, Michael; Schor, Paulo [UNIFESP]; Chamon, Wallace [UNIFESP]; Seiler, Theo; UniversitätsSpital Zürich; Universidade Federal de São Paulo (UNIFESP); Instituto de Física Aplicada
    Light spreads out uniformly at the same speed in all directions. Its position at any given moment is a sphere that connects all the corresponding phase points, having the source at its center. Such imaginary spherical surfaces are called light fronts or wavefronts. There are three principal factors that limit the finest details an eye can see: optical (due to scattering, diffraction, chromatic and monochromatic aberration), retinal and neural factors (limiting visual acuity to an approximate maximum of 20/10 or 2.0). A mathematical system, the Zernike polynomials, can define geometrical surfaces in order to describe the monochromatic aberrations, both for the lower order aberrations ('prism', 'sphere' and 'astigmatism') and the higher order ones ('coma', 'spherical aberration' and others). The wavefront measures the performance of the whole optical system of the eye. Both systems described herein, the aberrometer based on the Tscherning principle and the one originated from the Hartmann-Shack sensor, start from the same logic: to compare the actual position of the wavefronts with the ideal one, calculate mathematically the geometrical surface that describes that discrepancy and represent it in the terms of the Zernike polynomials. Corneal topography measurement, with adequate software, can also express the wavefront, caused by the corneal irregularities, with the Zernike polynomials, but it still represents the anterior corneal surface only. Wavefront technology offers a new way to quantify and classify optical imaging errors of the human eye. The next article will deal with the peculiarities of the wavefront analysis, as well as with some of the clinical and surgical applications to the day-to-day ophthalmic practice.
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    Frentes de ondas (wavefronts) e limites da visão humana Parte 2: aplicações
    (Conselho Brasileiro de Oftalmologia, 2002-12-01) Jankov, Mirko [UNIFESP]; Mrochen, Michael; Schor, Paulo [UNIFESP]; Chamon, Wallace [UNIFESP]; Seiler, Theo; UniversitätsSpital Zürich; Universidade Federal de São Paulo (UNIFESP); Instituto de Física Aplicada
    The mean values for all the Zernike coefficients are approximately zero, while the individual variability is very high, what means that humans as a species in general have a very good optical system, though individually imperfect. Some temporal instability of higher-order aberrations, whose largest source is accommodation has been described. There arises a new question: will the correction of all the aberrations for the non-accommodated state of the eye be as beneficial for the near sight also? It is possible to modify and decrease the optical aberrations by a process of photo-ablation carried out by a scanning spot LASER with the wavefront data serving as a basis for the customized ablation profile. Perfect alignment of the LASER beam on the eye by means of high frequency eye trackers is fundamental. The theoretical visual benefit by correcting the higher order aberrations is up to 12 times. The main goal of the wavefront-guided treatments is not to allow the decrease in visual acuity after refractive surgical treatments, as may occur nowadays with the traditional LASER treatments; the next step would be treatments aiming at the improvement of visual acuity, as well as the treatments of highly irregular corneas (primary irregular, small or decentered ablations, central islands or irregularities after corneal transplantation). Understanding the new terminology and the bases of the new technological evolution, together with the continuous and critical follow-up of the new results in the literature, is the key of success of the modern approach to the problems related to refraction and refractive surgery.
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    O impacto da cirurgia de ceratectomia fotorrefrativa (PRK) e ceratomileuse assistida por excimer laser in situ (LASIK) na qualidade visual e de vida em pacientes com ametropias
    (Conselho Brasileiro de Oftalmologia, 2008-02-01) Belfort, Ricardo [UNIFESP]; Campos, Mauro Silveira de Queiroz [UNIFESP]; Hoexter, Marcelo Queiroz [UNIFESP]; Belfort, Rubens Junior [UNIFESP]; Mari, Jair de Jesus [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    PURPOSE: To evaluate the quality of life, vision and stress before and after refractive surgery. METHODS: This is a longitudinal, observational study, where 100 patients were evaluated; 54 espectacles wearers, 21 contact lens users before surgery and 25 controls wearers spectacles or contact lenses, who did not want to undergo refractive surgery during one year despite refractive error. The applied questionnaires were Self Reporting Questionnaires SRQ-20 of quality of life and vision and National Eye Institute Visual Function Questionnaire NEI VFQ-25 for the assessment of mental health. The intervention group answered the questionnaires before surgery, three, six and twelve months after follow-up and the control group answered the questionnaires at six and twelve months after the baseline. The questionnaires of the intervention group were applied by an independent person. RESULTS: In the intervention group (54 spectacle wearers), 39 were treated by photorefractive excimer laserkeratectomy (PRK) and 15 by laser in situ keratomileusis (LASIK), of the 21 contact lens users: 12 received photorefractive excimer laser keratectomy and nine were treated by laser in situ keratomileusis (LASIK). The control group remained stable during the study. After three months of follow-up the intervention group showed improvement in quality of life, vision and reduction of stress. After one year of follow-up the assessments of quality of life and mental health were similar to the control group. After three months there was a significant reduction of psychiatric symptomatology in the intervention group. CONCLUSION: Patients operated for correction of ametropia showed a significant improvement in quality of life and mental health assessments.
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    Intraocular lens power calculation by measuring axial length with partial optical coherence and ultrasonic biometry
    (Conselho Brasileiro de Oftalmologia, 2011-06-01) Fontes, Beatriz Machado; Fontes, Bruno Machado [UNIFESP]; Castro, Elaine; Centro de Microcirurgia e Diagnóstico; Universidade Federal de São Paulo (UNIFESP); Oftalmoclínica Méier
    PURPOSE: To compare the achieved refractive outcomes of patients undergoing cataract surgery with intraocular lens (IOL) power calculation performed by conventional immersion ultrasound (US) or partial coherence interferometry (PCI). METHODS: Prospective, comparative case series. Patients undergoing cataract surgery were randomly divided in two groups with regard to the IOL power calculation method. Group 1 had calculations performed by PCI (IOL Master; Carl Zeiss Meditec), while US was used in Group 2 (Ultrascan; Alcon), using the Holladay 1 formula. Differences between target and achieved refractions were then compared. RESULTS: The study comprised 120 eyes from 79 patients. Biometry with PCI was used in 50 eyes of 33 patients, and US was used in 70 eyes of 46 patients. Mean age of patients in the PCI Group was 69.8 ± 13.1 years (range 11 - 85) and 70.0 ± 9.3 (45 - 86) in the US Group (P=0.7165). Mean axial length measured by PCI was 23.22 ± 1.00 mm (range 21.01 - 25.45) and that by US was 23.22 ± 1.06 mm (20.05 - 25.78) (P=0.9110). Mean absolute error in the PCI group was 0.15 ± 0.33 D (range -0.65 - 0.9) and that in the US group was 0.26 ± 0.48 D (-1.05 - 1.76). All eyes in the PCI group and 94.3% of those in the US group were within 1.00 D of the planned refraction. CONCLUSION: Although both PCI and US yielded good prediction in IOL power calculation, the PCI group tended to show better accuracy and improved refractive outcome.
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    Keratoconus prediction using a finite element model of the cornea with local biomechanical properties
    (Conselho Brasileiro de Oftalmologia, 2009-04-01) Carvalho, Luis Alberto [UNIFESP]; Prado, Marcelo; Cunha, Rodivaldo H.; Costa Neto, Alvaro; Paranhos Junior, Augusto [UNIFESP]; Schor, Paulo [UNIFESP]; Chamon, Wallace [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Hospital Albert Einstein Departamento de Oftalmologia
    PURPOSE: The ability to predict and understand which biomechanical properties of the cornea are responsible for the stability or progression of keratoconus may be an important clinical and surgical tool for the eye-care professional. We have developed a finite element model of the cornea, that tries to predicts keratoconus-like behavior and its evolution based on material properties of the corneal tissue. METHODS: Corneal material properties were modeled using bibliographic data and corneal topography was based on literature values from a schematic eye model. Commercial software was used to simulate mechanical and surface properties when the cornea was subject to different local parameters, such as elasticity. RESULTS: The simulation has shown that, depending on the corneal initial surface shape, changes in local material properties and also different intraocular pressures values induce a localized protuberance and increase in curvature when compared to the remaining portion of the cornea. CONCLUSIONS: This technique provides a quantitative and accurate approach to the problem of understanding the biomechanical nature of keratoconus. The implemented model has shown that changes in local material properties of the cornea and intraocular pressure are intrinsically related to keratoconus pathology and its shape/curvature.