Technical notes on prism-dioptre and Prentice's rule.

PURPOSE: To show an alternative interpretation for prism-dioptre and access Prentice's rule accuracy. METHODS: Algebraic calculation. RESULTS: The prism-dioptre can be expressed as a percentage of the distance between the prism and the plane of prismatic dislocation. Prentice's rule is an imprecise mathematical expression prone to expressive errors. CONCLUSIONS: The prism-dioptre seems to be more informative when interpreted as a percentage. Prentice's rule is more effective as a pedagogical approach for introducing the concept of spherical lenses' prismatic image dislocation rather than a method for calculating its actual value.

Adult-onset Buphthalmos in Down Syndrome.

PURPOSE: To report a peculiar case of adult-onset buphthalmos. METHODS: Review of the medical record of a 24-year-old patient with Down syndrome who developed buphthalmos in the left eye after corneal transplantation for keratoconus. RESULTS: In the next 2 years after surgery, the operated eye evolved with chronic anterior uveitis that led to progressive peripheral synechiae, oscillating intraocular pressure, cataract, graft failure, and buphthalmos. CONCLUSIONS: The finding of buphthalmos of adult-onset in Down syndrome raises important issues concerning the classification of this eye condition and the responsibility for detecting and monitoring eyes with glaucoma in individuals with chromosome 21 trisomy.

Preoperative tranilast as adjunctive therapy to primary pterygium surgery with a 1-year follow-up.

PURPOSE: To determine the efficacy of tranilast as an adjunctive therapy in conjunctival autograft. METHODS: Twenty-nine patients were randomly allocated to the Tranilast Group (n=15) or the Control Group (n=14). The Tranilast Group received a subconjunctival injection of 0.5% tranilast 30 days prior to surgery. Conjunctival autograft was performed in both groups using fibrin sealant and 0.02% subconjunctival mitomycin C at the end of the surgery. After the resection of the pterygium, immunohistochemistry was performed with 100 cells to identify epithelial cells positive for transforming growth factor-ß (TGF-ß). Subjective symptoms were evaluated using a 5-point scale, and the recurrence rate was assessed. RESULTS: Both groups showed improvements in their symptoms and similar clinical results. Compared with the Control Group, the Tranilast Group failed to show a decreased recurrence rate (p=0.59). However, the number of epithelial cells expressing TGF-ß was lower in the Tranilast Group (5 cells; 95% CI: 2.56-13.15; Control Group, 16 cells, 95% CI: 11.53-24.76; p=0.01). Minimal but reversible complications, including glaucoma secondary to corticosteroids and granuloma, occurred during the study. CONCLUSION: Tranilast was effective in decreasing the number of pterygium epithelial cells expressing TGF-ß.

Preoperative tranilast as adjunctive therapy to primary pterygium surgery with a 1-year follow-up / Terapia auxiliar com o tranilast pré-operatório na cirurgia do pterígio primário com um ano de seguimento

Purpose: To determine the efficacy of tranilast as an adjunctive therapy in conjunctival autograft. Methods: Twenty-nine patients were randomly allocated to the Tranilast Group (n=15) or the Control Group (n=14). The Tranilast Group received a subconjunctival injection of 0.5% tranilast 30 days prior to surgery. Conjunctival autograft was performed in both groups using fibrin sealant and 0.02% subconjunctival mitomycin C at the end of the surgery. After the resection of the pterygium, immunohistochemistry was performed with 100 cells to identify epithelial cells positive for transforming growth factor-β (TGF-β). Subjective symptoms were evaluated using a 5-point scale, and the recurrence rate was assessed. Results: Both groups showed improvements in their symptoms and similar clinical results. Compared with the Control Group, the Tranilast Group failed to show a decreased recurrence rate (p=0.59). However, the number of epithelial cells expressing TGF-β was lower in the Tranilast Group (5 cells; 95% CI: 2.56-13.15; Control Group, 16 cells, 95% CI: 11.53-24.76; p=0.01). Minimal but reversible complications, including glaucoma secondary to corticosteroids and granuloma, occurred during the study. Conclusion: Tranilast was effective in decreasing the number of pterygium epithelial cells expressing TGF-β. .

Objetivo: Determinar a eficácia do tranilast, como terapia auxiliar no transplante autólogo de conjuntiva. Métodos: Vinte e nove pacientes foram randomizados em dois grupos: Grupo Tratado (15) e Grupo Controle (14). Trinta dias antes da cirurgia, o Grupo Tratado recebeu uma injeção subconjuntival de tranilast a 0,5%. O transplante autólogo de conjuntiva foi realizado em ambos os grupos, usando-se a cola de fibrina e a mitomicina 0,02% subconjuntival, ao final da cirurgia. Cada paciente foi examinado por 12 meses de acompanhamento. A imuno-histoquímica foi realizada, mediante um total de 100 células, a fim de que se contassem as células epiteliais positivas, para o fator de crescimento transformador beta (TGF-β), após a cirurgia do pterígio. Os sintomas subjetivos foram avaliados usando-se uma escala de cinco pontos, e a taxa de recorrência foi avaliada. Resultados: Os 2 grupos apresentaram melhora dos sintomas e com resultados clínicos similares. Quando comparado com o Grupo Controle, o Grupo Tratado falhou em mostrar uma diminuição da taxa de recorrência (p=0,59). Entretanto o número de células epiteliais expressando o TGF-β foi menor no Grupo Tratado (5 células; 95% CI=2,56-13,15; Grupo Controle, 16 células; 95% CI: 11,53-24,76, p=0,01). Complicações mínimas, mas reversíveis, ocorreram durante o estudo, incluindo glaucoma secundário ao uso de corticoide e granuloma. Conclusão: O tranilast foi efetivo em diminuir o número células epiteliais do pterígio expressando o TGF-β. .

Ultraviolet analysis of donated corneas: a portable prototype.

As technology improves human vision, some procedures currently performed may be causing a decrease of the natural UV protection of the cornea. A portable dual beam system prototype was assembled for physicians for clinical studies of these effects on the corneas endowing two types of 300-400 nm evaluations: 1, regularly donated corneas and 2, simulating refractive keratectomy by corneal lamellae removal. The system performs 500 measurements/s, providing ±0.25% precision for the transmittance. The measurements performed on the prototype are 95% in agreement with Cary 17 and HR4000CG-UV-NIR Ocean Optics spectrophotometers. Preliminary studies on cadaveric corneas demonstrate that, as the stromal layer is reduced (∼150 µm depth), there is significant loss--an average of 7.1%.--of the cornea's natural UV protection. The prototype is being tested in an eye bank for routine evaluation of donor corneas.

Keratometry device for surgical support.

BACKGROUND: High astigmatisms are usually induced during corneal suturing subsequent to tissue transplantation or any other surgery which involves corneal suturing. One of the reasons is that the procedure is intimately dependent on the surgeon's skill for suturing identical stitches. In order to evaluate the influence of the irregularity on suturing for the residual astigmatism, a prototype for ophthalmic surgical support has been developed. The final intention of this prototype is to be an evaluation tool for guided suture and as an outcome diminish the postoperative astigmatism. METHODS: The system consists of hand held ring with 36 infrared LEDs, that is to be projected onto the lachrymal film of the cornea. The image is reflected back through the optics of the ocular microscope and its distortion from the original circular shape is evaluated by developed software. It provides keratometric and circularity measurements during surgery in order to guide the surgeon for uniformity in suturing. RESULTS: The system is able to provide up to 23D of astigmatism (32D - 55D range) and is +/- 0.25D accurate. It has been tested in 14 volunteer patients intraoperative and has been compared to a commercial keratometer Nidek Oculus Hand-held corneal topographer. The correlation factors are 0.92 for the astigmatism and 0.97 for the associated axis. CONCLUSION: The system is potentially efficient for guiding the surgeon on uniformity of suturing, presenting preliminary data indicating an important decrease on the residual astigmatism, from an average of 8D - for patients not submitted to the prototype guidance - to 1.4D - for patients who have actually been submitted to the prototype guidance - after the first 24 hours post-surgery and in the subsequent weeks. It also indicates that the surgeon should achieve circularity greater or equal to 98% in order to avoid postoperative astigmatisms over 1D. TRIAL REGISTRATION NUMBER: CAAE - 0212.0.004.000-09.

Evaluation of a new system for obtaining donor lamellar grafts.

PURPOSE: To evaluate the performance of a new system for obtaining corneal lamellar grafts of preset sizes. The system consists of the combination of an artificial anterior chamber (MALKS) and an automated microkeratotome (MASYK). METHODS: A prospective study was performed. Lamellar tissue was obtained with the microkeratotome from 40 human corneoscleral buttons mounted in the artificial anterior chamber. The instrument was set to cut lamellae with a center thickness of 350 microm and a diameter of 10 mm. A new cutting blade for the microkeratotome was used for every 8 cases. Thickness was measured by ultrasound pachymetry. The lamellar diameter was assessed with a micrometric caliper. RESULTS: The center thickness of the corneal lamellae ranged from 230 to 430 microm (mean, 322 +/- 48 microm; 95% confidence interval [CI], 307-337 microm). The diameter of the stromal ranged from 9.26 to 10.74 mm (mean, 10 +/- 0.27 mm; 95% CI, 9.9-10 mm). There were no cases of perforation or incomplete/irregular lamellae. The interface between the residual stroma and the lamellae was macroscopically smooth. The repetitive use of the same blade up to 8 times did not significantly change these results. CONCLUSION: The MALKS and MASYK system showed good accuracy in obtaining lamellae of specific thickness and size taken from human corneoscleral buttons. It is a promising instrument for use in deep lamellar keratoplasty. The technique may be useful in obtaining precut lamellar donor tissue for distribution by eye banks.

Portable light transmission measuring system for preserved corneas.

BACKGROUND: The authors have developed a small portable device for the objective measurement of the transparency of corneas stored in preservative medium, for use by eye banks in evaluation prior to transplantation. METHODS: The optical system consists of a white light, lenses, and pinholes that collimate the white light beams and illuminate the cornea in its preservative medium, and an optical filter (400-700 nm) that selects the range of the wavelength of interest. A sensor detects the light that passes through the cornea, and the average corneal transparency is displayed. In order to obtain only the tissue transparency, an electronic circuit was built to detect a baseline input of the preservative medium prior to the measurement of corneal transparency. The operation of the system involves three steps: adjusting the "0 %" transmittance of the instrument, determining the "100 %" transmittance of the system, and finally measuring the transparency of the preserved cornea inside the storage medium. RESULTS: Fifty selected corneas were evaluated. Each cornea was submitted to three evaluation methods: subjective classification of transparency through a slit lamp, quantification of the transmittance of light using a corneal spectrophotometer previously developed, and measurement of transparency with the portable device. CONCLUSION: By comparing the three methods and using the expertise of eye bank trained personnel, a table for quantifying corneal transparency with the new device has been developed. The correlation factor between the corneal spectrophotometer and the new device is 0,99813, leading to a system that is able to standardize transparency measurements of preserved corneas, which is currently done subjectively.

Desenvolvimento de um sistema para contagem automatizada de celulas endoteliais da córnea / Development of an automatic measure system of corneal endothelial cells

A análise do endotélio de uma córnea doada é um dos procedimentos para se obter um laudo final quanto à sua qualidade o desenvolvimento de um sistema ótico automatizado, que realize medidas de forma objetiva e padronizada de córneas a serem utilizadas em transplante. Como, atualmente, essa análise é feita subjetivamente, o sistema em desenvolvimento deverá proporcionar uma avaliação objetiva da córnea dentro de seu meio de conservação, evitando, portanto, a sua descentrilização e danificação. Ainda, visa a aplicação imediata do sistema no Banco de Olhos do Hospital das Clínicas de Ribeirão Preto, que é responsável pela distribuição de córneas naquela cidade e região.

The corneal endothelium analysis is one of the used ways to evaluate the quality and viability of the donated cornea for the transplanting. The goal of the present work is the development of an automatic optical system for objectively measuring the donated corneas for transplant uses. As this measurement is generally subjectively done in the brazilian eye banks, the system in development should allow an objective evaluation of the cornea in its conservation environment avoiding damages. This system is to be implemented in the Banco de Olhos do Hospital das Clínicas de Ribeirão Preto, which is responsible for distributing corenas in that region.

Sistema de medidas automáticas de áreas de úlceras de córnea / Automatic measure systems of corneal ulcer area

Úlceras1 são feridas na córnea com alta potencialidade de cegueira, pois mesmo curadas tendem a tirar a transparência. Nos países em desenvolvimento e de natureza agrícola elas respondem por cerca de 10 por cento das causas de cegueira. Uma das formas do clínico acompanhar o tratamento delas é pela estimativa subjetiva de sua dimensão. Evoluções favoráveis tedem a promover uma diminuição da ferida. No entanto, as medidas existentes para essa estimativa são rudimentares. Assim, este trabalho apresenta o desenvolvimento de um sistema de captação de imagem em Lâmpada de Fenda (instrumento utilizado para analisar as córneas) e um "software" dedicado para o delineamento e cálculo da área úlcerada para ser implementado num hospital público (400 pacientes por semana). Inserido no contexto será desenvolvida uma biblioteca de arquivamento e análise de imagens de enfermidades corneanas.

Corneal Ulcer is a very common disease in agricultura! countries and it is responsible for 10% of the blindness causes. One of the main aspects to be observed in these cases is the increasing or decreasing of the affected area. We have been developing an automatic optical system in order to evaluate the affected area (the ulcer) to be implemented in a public hospital (400 patients per week are analyzed). The optical system is implemented in a Slit Lamp and connected to a CCD detector. The image is displayed in a PC monitor by a commercial frame grabber anda dedicated software for detennining the area ofthe ulcer has been developed.

Refrator ocular automático / Ocular autorefrator

Um sistema de medidas automáticas e objetivas de erros refrativos oculares (miopia, hipermetropia e astigmatismo), utilizando tecnologia laser, foi desenvolvido. O sistema consiste em projetar, através de um laser de diodo (lambida=850nm), um alvo luminoso (um anel) no fundo do olho do paciente e os feixes de luz que emergem do olho e atingem um detector CCD matricial são analisados quanto às suas vergências. Os feixes emergentes do olho testado são divididos em seis partes (três meridianos) e são analisados dois a dois pelo CCD. A distância entre as duas imagens formadas em cada meridiano fornece o poder de refração naquele meridiano. Com os poderes de refração dos três meridianos (0 graus, 120 graus e 240 graus) é possível determinar o erro refrativo ocular. Comparativamente com os sistemas por nós anteriormente desenvolvidos, este sistema utiliza o mesmo princípio básico de medidas, porém a forma do alvo de medida e o detector utilizados, resultaram num sistema menos complexo para o alinhamento ótico e com menor introdução de erros. Medidas em olhos artificiais e em olhos humanos foram realizadas apresentando excelente concordância com os resultados obtidos em consultórios oftalmológicos e estão dentro da precisão requerida para estes tipos de medidas (0,125di e 5 graus).

An automatic and objective system for measuring ocular refractive errors (myopia, hyperopia and astigmatism) was developed using laser technology. The system consists of projecting a light target (a ring), using a diode laser (À=850nm), at the fundus of the patient's eye. The light beams scattered from the retina are analyzed by a CCD detector (matrix) regarding their vergence. The beams which emerge from the tested eye are divided into six portions (three meridians) and are analyzed in pairs by the CCD. The distances between the two images in each meridian provide the refractive power in that particular meridian. As the refractive power is obtained for the fr meridians coº' 120° e 240°), it is possible to determine the ocular refractive error. This system uses the sarne basic principle for detecting the refractive errors as our previous ones 123, but the new measuring target and the detector have provided a less complex system for the optical alignment avoiding most of the measurement errors introduced in the other system. Measurements in artificial eyes and in human eyes were done and they are in good agreement with the retinoscopic measurements and also they are as precise as these kinds of measurement require (0,125di and 5°).