Early postoperative astigmatism in 2-mm manual small incision cataract surgery with phacofracture

Purpose: India’s cataract surgery rate has been hovering around a creditable 6000 per million population but the coverage is variable across the geography and demography with sharp urban rural divide. Smaller incisions in manual small incision cataract surgery (MSICS) with phacofracture have been credited with lower astigmatism and faster recovery, which is especially useful for patients traveling for surgeries. Methods: In this retrospective chart analysis based observational study of 66 eyes, we describe the early postoperative results with 2 mm MSICS with phacofracture. Results: The mean spherical equivalent of the autorefractor measured astigmatic error changed marginally to ?0.51 diopters (SD = 0.58) from ?0.44 diopters (SD = 0.42) (t = ?8.410, P = 0.0) translating to mean change in astigmatism of 0.14 DCyl when the axis was ignored. The keratometric difference between steepest and flattest axis of the anterior surface of the central 3 mm zone of the cornea changed from a mean of 0.89 diopters (SD = 0.55) to 1.39 diopters (SD = 1.03). The visual acuity improved to mean logarithm of the minimum angle of resolution (logMAR) score of 0.27 (SD = 0.33) at 1 week and 0.007 (SD = 0.04) which corresponds to 6/6P on Snellen’s acuity at 1 month or more. Conclusion: A 2 mm MSICS with phacofracture can deliver low astigmatism and good visual recovery in cataract surgery. The study underlines the need for considering the refraction at anterior and posterior corneal interfaces when the triplanar incision with separate interfaces is used.

Consideraciones actuales sobre el uso del optotipo LogMAR en la baja visión / Current considerations on the use of LogMAR optotype in low vision

Debe ser interés de todos los profesionales de la salud brindar un servicio de excelencia y de calidad que conlleve la satisfacción de las necesidades de los pacientes que concurran a las consultas de las diferentes especialidades. El examen clínico en todas sus fases es un eje medular para lograr este propósito, apoyado en los avances tecnológicos, pertinentes para la atención de cada paciente de manera individual. Por esta razón surgió la motivación de profundizar en el conocimiento y en la interpretación de los resultados obtenidos en la medición de la agudeza visual de los pacientes con baja visión y en la ambliopía profunda, atendidos en el Servicio de Baja Visión del Instituto Cubano de Oftalmología Ramón Pando Ferrer, mediante la utilización de optotipos de escala logarítmica. Para esto se realizó una exhaustiva, amplia y profunda revisión bibliográfica sobre el tema, que ayudó a aumentar y a mejorar el conocimiento sobre la utilidad y las ventajas del empleo del optotipo LogMAR en esta subespecialidad y en la Oftalmología en general(AU)

All the health professionals should be interested in providing excellent service of quality that meet the requirement of the patients who go to the different specialty services The clinical exam in all its phases is fundamental to achieve this purpose, supported by the technological advances and in line with the customized care of each patient. For these reasons, this study is aimed at delving into the knowledge and the interpretation of results achieved in the measurement, using logarithmic optotypes, of the visual acuity of low vision and deep ambliopia patients seen at the Low Vision Service of Ramon Pando Ferrer Cuban Institute of Ophthalmology. A comprehensive, broad and deep literature review was made on this topic, which helped to expand and to improve the knowledge on the usefulness and advantages of the use of LogMAR optotype in this subspecialty and in the ophthalmological field in general(AU)

Construction and validation of logMAR visual acuity charts in seven Indian languages

Purpose: The evaluation of visual impairment requires the measurement of visual acuity with a validated and standard logMAR visual acuity chart. We aimed to construct and validate new logMAR visual acuity chart in Indian languages (Hindi, Bengali, Telugu, Urdu, Kannada, Malayalam, and Assamese). Methods: The commonly used font in each language was chosen as the reference and designed to fit the 5 � 5 grid (Adobe Photoshop). Ten letters (easiest to difficult) around median legibility score calculated for each language based on the results of legibility experiment and differing by 10% were selected. The chart was constructed based on the standard recommendations. The repeatability of charts was tested and also compared with a standard English Early Treatment Diabetic Retinopathy Study (ETDRS) logMAR chart for validation. Results: A total of 14 rows (1.0 to -0.3 logMAR) with five letters in each line were designed with the range of row legibility between 4.7 and 5.3 for all the language charts. Each chart showed good repeatability, and a maximum difference of four letters was noted. The median difference in visual acuity was 0.16 logMAR for Urdu and Assamese chart compared to ETDRS English chart. Hindi and Malayalam chart had a median difference of 0.12 logMAR. When compared to the English chart a median difference of 0.14 logMAR was noted in Telugu, Kannada, and Bengali chart. Conclusion: The newly developed Indian language visual acuity charts are designed based on the standard recommendations and will help to assess visual impairment in people of these languages across the country.

A need for standardization in visual acuity measurement / Medida da acuidade visual e necessidade de padronização

ABSTRACT Standardization of terminologies and methods is increasingly important in all fields including ophthalmology, especially currently when research and new technology are rapidly driving improvements in medicine. This review highlights the range of notations used by vision care professionals around the world for vision measurement, and the challenges resulting from this practice. The global community is urged to move toward a uniform standard.

RESUMO Nos tempos atuais, quando a pesquisa e a tecnologia estão avançando rapidamente, as melhorias na medicina, a padronização de terminologias e métodos está se tornando cada vez mais importante em todos os campos, incluindo a oftalmologia. Os profissionais de cuidados da visão em todo o mundo usam várias notações para a medição da visão. Nesta revisão, os autores destacam os desafios enfrentados por essa abordagem. A comunidade global precisa adotar um padrão uniforme.

Development of Pocket Vision Screener and its effectiveness at screening visual acuity deficits.

Aim: The aim was to construct a visual acuity chart and find its effectiveness at screening visual acuity deficits. Materials and Methods: Two phases were involved in this study.Construction of the screener: Ten Sloan letters (C, D, H, K, N, O, R, S, V, and Z) were selected and the letters were constructed and reduced to 0.2 logMAR acuity size (6.92 mm) for viewing at 3 m. The screener contains three lines with seven letters in each. Few combinations of the seven letter sequences were chosen based on the row legibility scores. Three seven letter combinations close to the median of all combinations were selected, such that maximum difficulty score difference between the lines are <1%. Finding the effectiveness of the screener: 100 literate subjects with unaided visual acuity better than or equal to 6/60 were recruited for the study. Unaided visual acuity was tested using both the newly constructed Pocket Vision Screener and a logMAR visual acuity chart and the time taken to measure the visual acuity using both the charts was noted. Results: The mean age of the subjects was 43 ± 17 years. Subjects were classified as normal or deficient based on the logMAR visual acuity measurement. The screener was found to have 81% sensitivity, 94% specificity. The positive and negative predictive values were found to be 91% and 87%, respectively. A significant difference (P < 0.001) was found in the time taken to record visual acuity using both the charts. Conclusion: The Pocket Vision Screener can be used as a quick and accurate tool to screen subjects for visual acuity deficits, being highly sensitive, specific, and cost‑effective.

A new Gujarati language logMAR visual acuity chart: Development and validation.

Aims: Gujarati is the main spoken language of a large proportion of the population of India. The aim of this study was to develop and validate a new Minimum Angle of Resolution (logMAR) visual acuity chart in the Gujarati language. Materials and Methods: A new Gujarati visual acuity chart was designed to logMAR specifications using Gujarati optotypes experimentally selected to have similar relative letter legibility under spherical and cylindrical defocus. The chart validation study was carried out using 153 adult subjects in a large clinical setting in India. Subjects who were literate in English and Gujarati participated in the study. Visual acuity was measured with the new Gujarati logMAR chart and a modified Early Treatment of Diabetic Retinopathy Study‑(m‑ETDRS) logMAR chart. The method of presentation was randomized between the charts. Repeat visual acuity was measured on a subsequent day with a second version of the Gujarati logMAR chart. Results: The Gujarati chart correlated highly with the m‑ETDRS logMAR chart (r2 = 0.974). The mean visual acuity difference (Gujarati – m‑ETDRS logMAR) was equal to three letters (–0.06 logMAR). The Gujarati logMAR chart also proved to be highly repeatable (r2 = 0.994, test‑retest) with 95% CI of ± 0.04 logMAR. Conclusions: The new Gujarati logMAR visual acuity chart provides a valid and repeatable tool for the measurement of visual acuity in native Gujarati language speakers.

Variaciones en el grado de aberraciones ópticas corneales de alto orden en pacientes diagnosticados con ectasias corneales implantados con anillos intraestromales / Variations on the degree of high order corneal optical aberrations in patients diagnosed with corneal ectasia with intrastromal rings implanted

Objetivo: identificar si existen variaciones significativas en el grado de aberraciones corneales de alto orden después del implante de los anillos intraestromales, en pacientes diagnosticados con ectasias corneales. Materiales y métodos: se realizó un estudio analítico y longitudinal de intervención en pacientes mayores de 18 años. Se valoró el estado refractivo; la agudeza visual medida con log mar; la queratometría topográfica; las aberraciones ópticas corneales coma, trifoid, esférica y el Root Mean Square High Order (rms Ho), mediante el topógrafo Keratron Scout, y la calidad visual por medio de la prueba de letras de Mars para la sensibilidad al contraste. Todo lo anterior en tres momentos antes de la intervención, primer y tercer mes postoperatorio. Resultados: en 39 ojos de 26 pacientes evaluados antes, al mes y al tercer mes después del implante se presentaron diferencias significativamente clínicas, aunque no estadísticas: a) se incrementó la agudeza visual sin corrección, b) hubo disminución del valor esférico y cilíndrico, c) aplanamiento en la K1 y K2, d) diferencias en cuanto al grado de aberraciones ópticas de alto orden corneales, después del procedimiento, e) una mejor calidad visual para estos pacientes y f) uso de lentes oftálmicos con mayor tolerancia. Conclusión: las aberraciones ópticas de la superficie anterior de la córnea no presentan una diferencia estadísticamente significativa antes y después del implante de segmentos intraestromales, aunque sí existen cambios a nivel clínico y en magnitud.

Objective: To identify whether there are significant variations in the degree of higher-order corneal aberrations after implantation of intrastromal rings in patients diagnosed with corneal ectasia. Materials and methods: An analytical and longitudinal study of intervention in patients over 18 years was carried out. The refractive state was evaluated, as well as the visual acuity measured by logmar; the topographic keratometry, the corneal optical aberrations coma, the trifoid, the spherical and the Root Mean Square High Order (rms Ho), by the Keratron Scout topograph, and the visual quality through Mars letters test for contrast sensitivity. All of this was done in three times before surgery, first and third post-op months. Results: In 39 eyes of 26 patients evaluated before, after one and three months after the implantation, clinical differences were significant, though not statistical: a) visual acuity was increased with no correction, b) there was a decrease in spherical and cylindrical values, c) flatten ng in K1 and K2, d) differences in the degree of high order optical aberrations of cornea after the procedure, e) a better visual quality for these patients and f) use of ophthalmic lenses with a greater tolerance. Conclusion: The optical aberrations of the anterior surface of the cornea do not have a statistically significant difference before or after the implantation of intrastromal segments, although there are changes at a clinical level and in magnitude.

Sweep pattern visual evoked potential acuity in visual developing children / 中华实验眼科杂志

BackgroundSweep pattern visual evoked potential(SPVEP) acuity,as an objective detective technique of visual function,can be used to measure visual acuity in children and uncooperative adults.Recent studies have shown that the amplitude-logarithm of the visual angle (A-LogVA) function regression method was more accurate than the amplitude-spatial frequency (A-SP)function regression method in evaluating SPVEP acuity.Objective This study was to explore the clinical use of SPVEP acuity in visual developing children and compare the evaluating the SPVEP acuity of children between A-SP function regression method and A-LogVA function regression method.Methods Twenty-six eyes of 26 asthenopic children with age range of 3-12 years and 31 age-matched normal children were enrolled in this study.SPVEP acuity was recorded with GT-2000 NV ( GUOTE MEDICAL APPARATUS LTD,China) using sinusoidally modulated horizontal gratings of 10 different spatial frequencies from 0.99 to 12.89 cpd as stimulus.The responses were averaged and displayed through discrete Fourier transformations (DFT) on the monitor display.SPVEP acuity was estimated by using both the SPVEP A-SP function regression method and the SPVEP A-LogVA function regression method.The LogMAR chart was used to acquire LogMAR visual acuity.ResultsIn the normal group,the correlation coefficient between LogMAR visual acuity and acuity calculated by the A-SP function regression method was 0.600 (P＜0.01).The correlation coefficient between LogMAR visual acuity and acuity calculated by the A-LogVA function regression method was 0.733 ( P＜0.01 ).The ANOVA of the LogMAR acuity and the SPVEP acuity calculated from the A-SP function regression method and A-LogVA function regression method were 113.173 (P＜0.01 ),which indicated that there were significant difference among all of subjects.The differences of the mean values of LogMAR visual acuity and the SPVEP acuity calculated from the A-SP function regression method and A-LogVA function regression method were respectively 0.40±0.02,0.26 ±0.02 and 0.14 ± 0.02.In the amblyopia group,the correlation coefficient between LogMAR visual acuity and acuity calculated by the A-SP function regression method was 0.134 (P =0.515 ).The correlation coefficient between LogMAR visual acuity and acuity calculated by the A-LogVA function regression method was 0.456 ( P＜0.05 ).The ANOVA of the LogMAR acuity and the SPVEP acuity calculated from the A-SP function regression method and A-LogVA function regression method were 3.433 (P＜0.05),indicating that there were significant difference among all of subjects.The differences of the mean values of LogMAR visual acuity and the SPVEP acuity calculated from the A-SP function regression method and A-LogVA function regression method were 0.07±0.05,0.12±0.05 and 0.05 ±0.01 respectively.Conclusions SPVEP can evaluate the visual acuity in children,although SPVEP acuity may overestimate or underestimate acuity in comparison with different LogMAR visual acuities.The amplitude-LogVA function regression method is more accurate in extrapolating SPVEP acuity.

Comparison of two methods of extrapolating sweep pattern visual evoked potential acuity / 中华实验眼科杂志

Background Sweep pattern visual evoked potential (SVEP) is an objective method of visual test.There is a clear correlation between SVEP acuity and subjective vision,but they are not identical.Recent studies showed that new regression method can improve the accuracy of SVEP acuity. Objective This trial was to investigate and compare the outcome between amplitude-spatial frequency (A-SP) regression method and amplitudelogVA (A-logVA) regression method in extrapolating the SVEP acuity.Methods SVEP was recorded in 113 eyes of 64 subjects using GT-2000 ( Guo Te,China) with the gratings of 10 different spatial frequency from 0.99 to 12.89 cpd as stimulus.The 1 13 eyes included cataract,glaucoma,corneal disease,optical neuropathy,retinal disease,ocular trauma,refractive error and normal eyes.The correlation were analyzed of SVEP acuity,decimal visual acuity and LogMAR visual acuity.The response were averaged and DFT on the monitor display.SVEP acuity was calculated by extrapolating 0 response amplitude.Results The correlation indices of decimal visual acuity curves obtained by the A-logVA function was 0.663,and that obtained by the A-SP function was 0.705.The positive correlation was seen between subjective decimal visual acuity and A-logVA decimal visual acuity (r =0.540,P＜ 0.01 ) and between subjective decimal acuity and decimal acuity calculated by the A-SP regression method (r=0.620,P＜0.01 ).SVEP decimal acuity calculated by the A-SP function regression method was significantly different from the that calculated by the A-logVA function regression method (Z =-8.688,P＜0.01 ).And the correlation indices of LogMAR visual acuity curves obtained by the A-logVA function was 0.733 and that obtained by the A-SP function was 0.715.The positive correlation was found between the subjective LogMAR acuity and that calculated by the A-SP regression method (r=0.700,P＜ 0.01 ) and between the subjective LogMAR acuity and LogMAR acuity calculated by the A-logVA regression method (r=0.710,P＜0.01 ).SVEP LogMAR acuity from A-SP function regression method was significantly different from the LogMAR acuity from A-logVA function regression method (Z=-8.748,P＜0.01 ).No significant differences of VA LogMAR were found in gender,eyes,type of disease and age(x2 =2.171,P=0.338;x2 =0.976,P=0.614;x2 =6.032,P=0.420;x2 =14.720,P=0.257 ).Conclusions SVEP can obtain the visual outcome in human.The amplitude-logVA function regression method is more accurate in extrapolating SVEP acuity.

Prueba piloto para determinar la reproducibilidad de la carta de Snellen al evaluar la agudeza visual en sujetos jóvenes / Pilot trial to determine the reliability of the snellen chart for assessment of the visual acuity in young people

La agudeza visual es la principal característica evaluada para conocer cómo ve una persona. Al medirla se utilizan Cartas de Agudeza Visual, de las cuales la más empleada en el medio colombiano es la carta Snellen. Objetivo: el propósito de esta investigación fue determinar la reproducibilidad ínter e intraobservador de la carta de letras serif Snellen para evaluar la agudeza visual (AV). Materiales y métodos: en un muestreo por conveniencia, dos evaluadores midieron en dos sesiones la AV con la carta de Snellen tipo serif en 110 estudiantes universitarios (220 ojos) entre 15 y 30 años de edad, con ametropía corregida, visión binocular normal y sin patologías del segmento anterior o posterior. Se repitieron las pruebas en los pacientes induciendo una miopía de 1,50 D. Los valores de AV fueron convertidos de la escala fraccional a la logarítmica. Resultados: los resultados mostraron que la AV promedio (LogMAR) fue -0,06 (20/20+5); con la miopía inducida, 0,51 (20/63). La prueba de Wilcoxon pareada mostró diferencias significativas para la primera sesión entre los dos evaluadores (p = 0,0001; p = 0,007) y con el defecto inducido interevaluadores en las dos sesiones (p = 0,03; p = 0,001). El coeficiente de correlación y concordancia de Lin (Pc) indicó pobre concordancia (Pc = 0,9) ínter e intraobservador, sin defecto inducido y con éste. Los límites de concordancia de Bland-Altman muestran variaciones de AV de 3 líneas en los sujetos corregidos y de 5 a 6 líneas de visión con la miopía inducida. Conclusiones: la carta de Snellen presenta concordancia baja y variabilidad en los resultados moderada-alta, por lo que se sugiere la realización de estudios que evalúen la validez de la prueba en las poblaciones sana y con alteraciones visuales.

The visual acuity is the main characteristic evaluated to know how a person sees. For the visual acuity measuring it is used the letter chart, in Colombia the most used it is the Snellen Chart. Objective: To determinate the reliability inter e intraevaluator of Snellen Chart to test visual acuity. Methods: With convenience sampling two evaluators tested visual acuity with serif Snellen Chart to 110 subjects (220 eyes) who were university students between 15-30 years old, full distance refractive correction, normal binocular vision, and no pathologies of anterior and posterior of eye. A refractive error (myopia 1.50D) was induced for all the subjects and the trials were carrying out.Results: Visual acuity means was -0.06 (20/20+5), with induced myopia 0.51 (20/63). Wilcoxon sign rank test showed difference between inter evaluators (p=0,0001; p=0,007) in first trial and wearing plus lens +1.50D between inter evaluators in both trials ((p=0,03; p=0,001). Conclusions: Correlation Coefficient and Concordance of Lin showed a poor concordance and a moderated-high variability in the outcomes; then, Snellen chart has a poor concordance and moderate variability, so we suggest achieving researches about the validity of this test in the population with normal and subnormal vision.

Pruebas para la evaluación de la agudeza visual en pacientes pediátricos / Tests for the visual acuity assessment in pediatric patients

La medición de la agudeza visual en niños representa un importante reto para el optómetra por ser laboriosa y requerir conocimiento y paciencia. Según el estímulo, la agudeza visual puede dividirse en tres tipos: de detección, de resolución y de reconocimiento. Los valores de estas pueden ser diferentes y se alteran en diferente proporción en presencia de problemas visuales. El presente artículo hace una revisión de los tests de agudeza visual para niños, sobre los que se han realizado gran número de investigaciones en los últimos años: Teller, Cardiff, Lea, HOTV y las cartillas logMAR que podrían emplearse en el grupo de escolares.Conclusiones: las pruebas contempladas en esta revisión no son necesariamente las más utilizadoas en nuestra práctica clínica cotidiana; sin embargo, la actividad investigativa en torno a éstas ha aportado a la construcción de protocolos diagnósticos. El referente para una mejor práctica clínica debe ser la optometría basada en la evidencia, ya que ésta permite a los profesionales disponer de nuevos elementos de juicio objetivos, con fundamento científico, que contribuyan a la elección de la mejor alternativa para determinar la agudeza visual en los niños. El optómetra debe seguir rigurosamente los protocolos de evaluación de la agudeza visual para dar a sus mediciones mayor confiabilidad y analizar los resultados obtenidos dentro del contexto de la historia clínica. Los métodos para la evaluación de la agudeza visual pueden adaptarse de acuerdo con las habilidades, el conocimiento y la experiencia del niño que va a examinarse. Con esta revisión se evidencia la importancia de realizar estudios sobre la aplicación de estos tests en nuestro medio con el fin de evaluar su confiabilidad y utilidad en nuestros pacientes.

The visual acuity measurement in children is an important Challenger for the optometrist, given de complexity of the task and to require knowledge and patience. According to the stimulus, the visual acuity can be divided in three types: detection, resolution and recognition. The values of these can be different and they are altered in different proportion in the presence of visual problems. The present article makes an overhaul of the test of the visual acuity for children which years have generated great number of investigations in the past years: Teller, Cardiff, Lea, HOTV and logMAR charts that could be used in the school age group.Conclusions: The tests reviewed are not necessarily used commonly used our clinical daily practice, nevertheless the investigative activity concerning these has reached in the construction of diagnostic protocols. The reference for a better clinical practice must be the optometry based on the evidence, since this one allows to the professionals to have new facts that contribute to the election of the best alternative to determine the visual acuity in the children. The optometrist a must follow rigorously the protocols of evaluation of the visual acuity to give to measurements major reliability and to analyze the results obtained inside the context of the history. The methods for the evaluation of the visual acuity can be adapted in agreement with the skills, knowledge and experience of the child being examinated. There is evident the importance of realizing studies on the application of these test in order to evaluate their reliability and utility in our patients

A new standardized logMAR visual acuity chart: development and clinical application / 第二军医大学学报

Objective:To introduce a new standardized logMAR visual acuity chart and its clinical application.Methods: The new visual acuity chart and notations were designed based on Weber-Fechner theorem.The E optotype on the chart had 3 limbs of equal length.A regular geometric progression of optotype sizes and distribution was employed to arrange 14 lines with 4 optotypes on each line.The progression rate of optotype size between 2 lines was 10 and the testing distance was 3 m.The visual acuity score could be recorded as logarithm of the minimum angle of resolution(logMAR) notation or decimal notation.The reliability of naked distant measurements with this new chart was tested in one eye of 100 subjects taking the Chinese national standard logarithm visual acuity chart(CSVAC) standard.Results: This new chart overcame the shortcomings of different number of optotypes on each line and fewer optotypes at the top of CSVAC.Several visual acuity notations were adopted and conversion between different notations was very convenient in this new chart.The measurements of this new chart had significant correlation and good agreement with CSVAC.Conclusion: The new standardized logMAR visual acuity chart is reliable,easy to use and accurate.It can be applied in clinical teaching and research of ophthalmology and optometry.

A New LogMAR Vision Chart: Jin`s Vision Chart

A new vision chart has been developed. This chart utilizes geometric progression of optotype size instead of arithmetic progression. The optotype is increased or decreased in its size by 1.25X (0.1 log unit) when a line changes. It becomes double or half by change of 3 lines. this principle is based on the suggesstion of International Standard Organization (ISO 8596). There are 3 kinds of vision chart; each one for adult, for children and landolt`s ring chart. They are available in one set. The basic distance for examination is 4 m, but it can be used in 3.25, 5and 6.25m. Five optotypes are arranged in each line, and the corresponding visual acuity is given when more than 3 letters are recognized correctly. The correlation coefficient when compared to ladolt`s ring chart were 0.88 with adult chart and 0.91 with children`s chart.