Correção óptica e evolução da hipermetropia / Optical correction and evolution of hipermetropy

Resumo Objetivo: Comparar as alterações da refração e da biometria ocular na população infantil hipermetrópica com e sem correção óptica total. Métodos: Realizou-se estudo prospectivo longitudinal não randomizado em 41 pacientes com hipermetropia, entre 3 e 6 dioptrias ou/e com esotropia acomodativa pura nos ambulatórios do Hospital Geral Universitário e Oftalmocenter Santa Rosa, com idade inicial entre 4 e 6 anos. Os pacientes foram divididos em dois grupos, em que o Grupo 1 compôs-se pelos pacientes hipermétropes que não necessitavam usar sua correção óptica ou poderiam usá-la parcialmente, e o Grupo 2 por pacientes com esotropia acomodativa pura e pelos hipermétropes que necessitavam usar toda sua correção óptica. Os pacientes submeteram-se a exame oftalmológico completo, incluindo refração objetiva em autorrefrator com cicloplegia, biometria óptica e topografia corneana em uma medida inicial e outra 3 anos mais tarde. Comparou-se a refração e parâmetros biométricos com teste T student. Resultados: A média da idade inicial foi de 5,23 ± 0,81 e 5,36 ± 0,74 anos, a refração inicial foi +3,99 ± 0,92 e +4,27 ± 0,85 D, o diâmetro anteroposterior do globo ocular foi de 21,42 ± 0,84 e 21,22 ± 0,86 mm, e a ceratometria foi de 42,55 ± 1,24 e 42,39 ± 1,22 D, para os Grupos 1 e 2, respectivamente. Em relação à refração, houve redução significativa do poder esférico no Grupo 1, em 3 anos; e não houve no Grupo 2 (p<0,05). Com relação ao diâmetro anteroposterior do globo ocular, ocorreu aumento significativo no Grupo 1 e não houve no Grupo 2 (p<0,05 ). Não se verificou diferença significativa na comparação das ceratometrias em 3 anos nos Grupos 1 e 2. Conclusão: Estes dados permitiram concluir que a correção total da hipermetropia pode prejudicar a emetropização natural em crianças.

Abstract Objective: To compare changes in refraction and ocular biometric parameters in hyperopic children with and without full optical correction. Methods: Non-randomized prospecting study with 41 subjects (21 males and 20 females) aged 4 to 6 years with accommodative esotropia and or hyperopia between 3 to 6 diopters, select in Hospital Geral Universitário and Oftalmocenter Santa Rosa. The patients were divided in two groups: group 1 for hyperopic patients that did not need to use optical correction or could use partial correction, and group 2 for patients with accommodative esotropia or hyperopia who needed to use full optical correction all the time. The patients were examined to a complete ophthalmological examination, including objective cycloplegic refraction with auto refractometer, optical biometry and corneal topography, in baseline measurements and 3 years after that. Refraction and ocular biometric parameters were compared using T student test. Results: The mean initial age was 5.23 ± 0.81 and 5.36 ± 0.74 years; the initial refractive error in average was +3.99 ± 0.92 e +4.27 ± 0.85 D, the initial axial length was 21.42 ± 0.84 and 21.22 ± 0.86 mm, and initial keratometry was 42.55 ± 1.24 e 42.39 ± 1.22 D for group 1 and 2, respectively. In relation to refractive error, there was a significant decrease in group 1 and there was not in group 2 (p < 0.05). In relation to axial length, there was significant increase in group1 and there was not in group 2 (p<0.05). The 3-year comparison showed no statistically significant differences in keratometry for both groups. Conclusion: This study suggests that full optical correction of hyperopia may inhibit natural emmetropization during early and late childhood.

Biometria no crescimento do olho alto míope na infância / Biometry in the growth of the high myopic eye in childhood

OBJETIVO: Determinar se o crescimento do globo ocular mensurado através da biometria óptica e ultrassônica em uma população pediátrica de altos míopes é significante, assim como variação significante da espessura do cristalino, profundidade da câmara anterior, curvatura corneana e achados fundoscópicos durante o acompanhamento. MÉTODOS: Uma população pediátrica (idade média: 8,7anos), 11 olhos de crianças portadoras de alta miopia (refração média inicial: -11,28D) foi submetida a avaliação seriada num período de nove meses incluindo-se biometria óptica (IOLMaster, Zeiss) e ultrassônica (Ultrascan, Alcon; técnica de contato), refratometria estática, oftalmoscopia indireta e retinografia. RESULTADOS: No período de nove meses, o crescimento do olho foi estatisticamente significante em 64% (7 olhos) e não ocorreu em 36% (3 olhos), com modificação do comprimento axial médio (pré=26,76 mm; final=26,98 mm). Neste período, o equivalente esférico refracional aumentou em 45% (5 olhos), não apresentou variação em 27% (3 olhos), com modificação da refração média (pré=-11,28 D; final=-11,69 D). Não houve variação estatisticamente significante da espessura do cristalino, profundidade da câmara anterior, curvatura corneana e do aspecto fundoscópico. CONCLUSÃO: No grupo de crianças com alta miopia acompanhadas num período de nove meses, demonstrou-se o crescimento do globo ocular com variação do comprimento axial tanto pela técnica de biometria óptica quanto ultrassônica, e com aumento da refratometria média. Outros parâmetros estudados como espessura do cristalino, profundidade da câmara anterior e curvatura da córnea não demonstraram variação no período de tempo do estudo.

PURPOSE: To determine if the growth of the axial length measured by optical and ultrasound biometry in a pediatric population of high myopes is significant, as well as significant variation of lens thickness, anterior chamber depth, corneal curvature and ophthalmoscopic findings during follow-up. METHODS: A pediatric population (mean age: 8.7 years old) of 11 high myopic eyes (mean initial refractive error: -11.28 D) was submitted to serial evaluation over a 9-months period including optical (IOLMaster, Zeiss) and ultrasound biometry (Ultrascan, Alcon, contact technique), cycloplegic refraction, indirect ophthalmoscopy and fundus photography. RESULTS: During a 9-months period, eye growth was significant in 64% (7 eyes) and did not occur in 36% (3 eyes), with change in the mean axial length (pre=26.76 mm; final=26.98 mm). During this period, refractive spherical equivalent increased in 45% (5 eyes), did not show variation in 27% (3 eyes), with a change in mean refraction (pre=-11.28 D; final=-11.69 D). There was no statistically significant variation of lens thickness, anterior chamber depth, corneal curvature and ophthalmoscopic findings. CONCLUSION: Ocular globe growth (axial length) measured by optic and ultrasound biometry was significant in the high myopic pediatric population examined. The findings suggest that axial length variation preceded variation of other structures in the sample examined. In a group of children with high myopia followed during a 9-months period, ocular growth was demonstrated with variation of axial length either with optical or ultrasound biometry techniques, and change in mean refraction. Other parameters studied as lens thickness, anterior chamber depth and corneal curvature did not demonstrate variation during the time of the study.

Growth of the human lens in the Indian adult population: Preliminary observations.

Context: The eye lens grows throughout life by the addition of new cells inside the surrounding capsule. How this growth affects the properties of the lens is essential for understanding disorders such as cataract and presbyopia. Aims: To examine growth of the human lens in the Indian population and compare this with the growth in Western populations by measuring in vitro dimensions together with wet and dry weights. Settings and Design: The study was conducted at the research wing of a tertiary eye care center in South India and the study design was prospective. Materials and Methods: Lenses were removed from eye bank eyes and their dimensions measured with a digital caliper. They were then carefully blotted dry and weighed before being placed in 5% buffered formalin. After 1 week fixation, the lenses were dried at 80 °C until constant weight was achieved. The constant weight was noted as the dry weight of the lens. Statistical Analysis Used: Lens parameters were analyzed as a function of age using linear and logarithmic regression methods. Results: Data were obtained for 251 lenses, aged 16–93 years, within a median postmortem time of 22 h. Both wet and dry weights increased linearly at 1.24 and 0.44 mg/year, respectively, throughout adult life. The dimensions also increased continuously throughout this time. Conclusions: Over the age range examined, lens growth in the Indian population is very similar to that in Western populations.

La evolución de los ojos / The evolution of the eyes

La evolución de los ojos comenzó cuando comenzó la vida misma. Incluso las formas de vida más simples, las bacterias, tienen las primeras proteínas fotosensibles. Desde las bacterias la vida y la visión evolucionaron hacia una asombrosa variedad y complejidad: ojos telescópicos, ojos especulares, ojos tipo cámara, todos ellos con un solo origen.

The evolution ofthe eyes began when the life itself began. Even the simplest life forms, the bacteria, have the first photosensitive proteins. From the bacteria, the life and the vision evolved towards an astonishing variety and complexity: telescope eyes, mirror eyes, camera eyes, between many others, all ofthem with a single source.

Eye malformations induced by carbamazepine in mice

Neural tube defects, growth retardation and nail hypoplasia are most common features of teratogenic effects of carbamazepine. This study was done to determine the effects of carbomazepine on eye development in Mice fetuses. In this experimental study 40 BALB/c pregnant Mice were divided into four groups. Experimental groups I and II received 15 mg/kg daily 6-15 GD [gestational days] and 30 mg/kg daily 6-15 GD intraperitoneal of carbamazepine, respectively. All drugs recolved in Tween20. Two control groups received normal saline or Tween 20. Dams were dissected on GD18 and embryos were collected. After observation of eye malformation in fetuses, we employed routine histological processes to stain the samples and also skeletal staining was performed. Calvaria deformations, finger anomalies, brachygnathia and short tail in experimental groups I and II were 7% and 10.8%, 13.3% and 16.6%, 7.8% and 11.7%, 10.2% and 9.2% respectively. Ten of fetuses [8.6%] in experimental group I and nine of fetuses [7.5%] in the experimental group II had eye malformations. Premature opening of one or both eyes with mild to severe exophthalmos occurred in both of the experimental groups. Also, histological examination showed deformed lens, retinal folds with undeveloped layers, corneal fold with absence of surface epithelium. This study revealed that administration of carbamazepine during embryunic period can induce eye malformations in Mice fetuses

Componentes oculares em anisometropia / The ocular components in anisometropia

Objetivo: Em anisométropes, comparar os valores médios individuais dos componentes oculares de ambos os olhos (poder da córnea, profundidade da câmara anterior, poder equivalente do cristalino e comprimento axial), correlacionar as diferenças dos componentes oculares com as diferenças de refração de ambos os olhos; verificar a contribuição total e a seqüência geral de influência das variáveis na diferença refrativa; e identificar o menor número de fatores que contenham o mesmo grau de informações expressas no conjunto de variáveis que influenciam na diferença refrativa. Métodos: Realizou-se um estudo transversal analítico em população de 77 anisométropes de duas ou mais dioptrias, atendida no ambulatório de Oftalmologia do Hospital Universitário da Faculdade de Medicina Nilton Lins, Manaus, Amazonas. Os anisométropes foram submetidos à refração estática objetiva e subjetiva, ceratometria e biometria ultra-sônica A-scan. A análise dos dados foi feita por meio dos seguintes modelos estatísticos: análise univariada, multivariada, de regressão múltipla e fatorial. Resultados: Não houve diferenças significativas na comparação dos valores médios individuais dos componentes oculares entre os olhos. Houve correlação negativa média entre a diferença refrativa e a diferença de comprimento axial (r=-0,64) (P<0,01) e correlação negativa fraca entre a diferença refrativa e a diferença de poder do cristalino (r=-0,34) (p<0,01). As variáveis analisadas responderam, no seu conjunto, por 78% da variação total para a diferença refrativa. A seqüência geral de influência das variáveis na diferença refrativa foi a seguinte: comprimento axial, poder do cristalino, poder da córnea e profundidade da câmara anterior. Foram identificados três fatores para a diferença refrativa: a) fator 1 (refração, comprimento axial); b) fator 2 (profundidade da câmera anterior, poder da córnea) e c) fator 3 (poder do cristalino). Conclusões: O estudo conduzido em 77 indivíduos com anisometropia...

Purpose: To compare the individual means of ocular components of both eyes (corneal power, anterior chamber depth, crystalline lens power and axial length) in patients with anisometropia; to correlate the differences of the ocular components with refractive differences in both eyes; to verify total contribution and the sequence of influence that variables have in refractive differences, and to identify the smallest number of factors that contain the same level of information expressed in the set of variables that influence refractive difference. Methods: An analytical transversal study was carried out in 77 patients with anisometropia of two or more dioptres seen at the Ophthalmologic Clinic, University Hospital, Medical School Nilton Lins, Manaus, Amazon state. All participants were submitted to ophthalmologic exam which included objective and subjective cycloplegic refractometry, keratometry and ultrasonic biometry. Data analysis comprised the following statistical models: univariate, multivariate, multiple and factorial regression analyses. Results: There were no significant differences in the comparison of the individual means of the ocular components. There was negative correlation between refractive difference and difference of axial length (r=- 0.64; p<0.01) and weak negative correlation between refractive difference and crystalline lens power difference (r=-0.34; p< 0.01). The analyzed variables amounted to 78% of the total variation of refractive difference. The general sequence of variables influencing refractive difference was: axial length, crystalline lens power, cornea power, and anterior chamber depth. There were three factors identified for refractive differences: a) factor 1 (refraction, axial length); b) factor 2 (anterior chamber depth, cornea power), and c) factor 3 (crystalline lens power). Conclusions: Seventy-seven cases of anisometropia ranging from 2,00 to over 19,00 dioptres, examined for the individual components of refraction...

GAL4 causes developmental defects and apoptosis when expressed in the developing eye of Drosophila melanogaster

The UAS/GAL4 ectopic expression system is widely used in Drosophila melanogaster for the overexpression of transgenes. This system operates under the assumption that the yeast transcription factor, GAL4, is inactive in D. melanogaster. Thus, GAL4 can be expressed under the control of D. melanogaster -specific promoters with little effect upon the organism. We have shown that expression of GAL4 in the developing eye under the control of the glass multiple reporter (GMR) promoter element does have an effect on eye development. Although GMR-GAL4 heterozygotes appear normal when raised at 25 degrees C, the homozygotes have a highly disorganized ommatidial array. In addition, the levels of apoptosis in the third-instar larval eye imaginal disc (where GAL4 is expressed) are slightly higher in GMR-GAL4 heterozygotes, and much higher in GMR-GAL4 homozygotes when compared to wild type discs. The morphological eye defects caused by GMR-GAL4 are significantly enhanced when flies are raised at 29 degrees C (presumably due to the higher activity of GAL4 at this temperature); however, the levels of apoptosis appear to be similar at these two temperatures. Taken together, these data suggest that GAL4 can have adverse effects on D. melanogaster development, especially at high expression levels. In addition, GAL4 appears to induce apoptosis even in the absence of any visible morphological defects. Thus, despite the benefits of the UAS/GAL4 ectopic expression system, one must use caution in the design and interpretation of experiments

The postembryonic development of the ocellar system of Triatoma infestans Klug (Heteroptera: Reduviidae)

Simple eyes or ocelli coexist with compound eyes in many adult insects. The change in the morphology of the ocelli along the five larval instars of Triatoma infestans was studied by light and scanning electron microscopy. Our analysis showed that the development of the ocelli of these bugs occurs gradually along the larval life. The photoreceptor layer is present from the second-instar onwards. The cornea appears first at the imaginal stage and grows up to the 18-20th day after the last ecdysis, associated to an increase in the retinal mass. Findings are discussed in a comparative fashion and in relation to the functionality of the ocellar system in T. infestans

Influencia de la deprivación por tarsorrafia y sección del nervio óptico: en el crecimiento del globo ocular en conejos albinos / Influence of the deprivation by tarsusraphy and section of the optical nerve: in the growth of ocular globe in albino rabbits

Los factores que determinan el crecimiento del globo ocular en el humano, se deben a fallas en el proceso de emetropización en el desarrollo más allá de sus valores normales. Los modelos animales han servido para estudiar la miopía axial inducida por deprivación visual. Estos experimentos se originan de hallazgos en humanos, en condiciones como catarata congénita monocular, ptosis congénita, etc, presentaban anisometría con un aumento del eje AP del globo ocular afectado. Se practicó tarsorrafia, más sección del nervio óptico en globos oculares de conejos, eliminando así la posible influencia del S.N.C. en la regulación del crecimiento del ojo con el objeto de estudiar las modificaciones en el crecimiento del globo ocular en ausencia de la influencia del S.N.C. tanto en condiciones de deprivación visual, como frente a estímulos visuales apropiados. Histopatológicamente se encontró una disminución importante del número de células ganglionares y desorganización de la capa de fibras nerviosas que demostró una sección efectiva del nervio óptico. Hubo diferencias significativas con respecto a los ejes AP a favor de los ojos sometidos a tarsorrafia. No se encontraron diferencias en el grosor de la esclera en los ojos en estudio y los controles. No hubo diferencias estadísticamente significativas en cuanto a peso, longitud horizontal y vertical. Concluímos que el crecimiento del globo ocular bien sea en condiciones de estimulación visual apropiada, o deprivación, no requiere la acción directa del S.N.C. y que el desarrollo normal hacia la emetropía, o a ametroptas como la miopía axial, son independientes de la regulación cortical cerebral y que probablemente sea dependiente de factores oculares locales tal vez retinianos

Effect of chloramphenicol on the development of the foetal eye: an experimental study

Chloramphinicol, a drug that produces adverse effects involving the eye, was intramuscularly [i.m.] administered to six pregnant female mice for three successive days starting on the 7th day of gestation aiming at screening its influence on the development of the eye. Three pregnant control female mice received only i.m. injections of sterile water on the same days of pregnancy as in experimental animals. Histological examination of eye specimens of experimental maternally-treated neonate mice with chloramphenicol revealed different degrees of corneal vacuolization. In some specimens corneal vacuolization was accompanied by discontinuity of the corneal endothelium and disruption of the posterior lamellae of the substantia propria and alterations in the contour of the lens. In other specimens apart from vacuolization and thickening of the cornea persistent connective tissue remnants were seen filling the anterior chamber. Moreover, different modalities of adherence between the anterior surface of the lens and the posterior surface of the cornea were indentified. These findings were discussed in relation to mesenchymal dysgenesis of the anterior segment of the eye specially Peter's anomaly

Crescimento do globo ocular humano: análise quantitativa no período fetal (9a. a 43a. semanas pós-concepçäo) / Growth of human ocular globe: quantitative analysis in fetal period (9th to 43th weeks post-conception)

Quantificaçäo do crescimento do globo ocular, no período prenatal humano (9a. a 43a. semanas pós-concepçäo) aplicando o método alométrico multiplicativo. Foi verificado que o crescimento do globo ocular apresenta proporçöes de 2,50 e 0,55 em relaçäo a idade gestacional e ao peso corporal, respectivamente. Esses dados corroboram com a literatura vigente, visto que os avanços tecnológicos propiciam o diagnóstico precoce de várias anormalidades