The influence of storage method on the transparency of pig crystalline lens / A influência do método de armazenamento na transparência do cristalino de porco

ABSTRACT Purpose: The porcine eye is frequently used as a research model. This paper analyzes the effect of different storage methods on the transparency of pig crystalline lens. Methods: A spectral transmission curve (from 220 to 780 nm) for the crystalline lens was determined experimentally after storage in different conditions: saline solution, formalin, castor oil, and freezing at -80°C. The total transmission in the visible spectrum, which was used as an index of transparency, was calculated from these curves. For comparative purposes, fresh lenses were evaluated and used as controls. Results: Storing the porcine crystalline lens in saline solution or castor oil resulted in a transparency loss of approximately 10% after 24 h and storage in formalin resulted in a loss of nearly 30%. Storage by freezing at -80°C for 4 weeks maintained the transparency of the crystalline lens; the spectral transmission measured immediately after defrosting at room temperature coincided exactly with that of the freshly extracted lens. Conclusions: The transparency of porcine crystalline lens is affected by the storage method. The visible spectrum is the most affected, evidenced by the effect on the transparency and consequently the amount of light transmitted. The results show that freezing at -80°C maintains the transpa rency of the crystalline lens for at least 4 weeks.

RESUMO Objetivos: Olho de porco é frequentemente usa do como modelos de pesquisa. Este estudo analisa o efeito de di ferentes métodos de armazenamento na preservação da transparência do cristalino de porco. Métodos: Uma curva de transmissão espectral (de 220 até 780 nm) para o cristalino foi experimentalmente determinada após armazenamento em diferentes condições: solução salina, formol, óleo de mamona e congelamento a -80°C. Transmissão total do espectro visível, que foi usada como um índice de transparência foi calculada a partir dessas curvas. Para fins comparativos, lentes frescas foram avaliadas e usadas como controles. Resultados: O armazenamento do cristalino suíno em solução salina ou óleo de mamona resultou uma perda de transparência de aproximadamente 10% após 24 h e o armazenamento em formol resultou uma perda de quase 30%. O armazenamento por congelamento a -80°C durante 4 semanas manteve a transparência do cristalino; a transmissão espectral medida imediatamente após o descongelamen to à temperatura ambiente coincidiu exatamente com a da lente extraída recentemente. Conclusão: A transparência do cristalino suíno é afetada pelo método de armazenamento. O espectro visível é o mais afetado, evidenciado pelo efeito sobre a transparência e consequentemente a quantidade de luz transmitida. Os resultados mostram que o congelamento a -80°C mantém a transparência do cristalino suíno por pelo menos 4 semanas.

The relationship of birth weight, gestational age, and postmenstrual age with ocular biometry parameters in premature infants / A relação entre o peso ao nascer, idade gestacional e idade pós-menstrual com a biometria ocular em bebês prematuros

ABSTRACT Purpose: To analyze ocular biometry parameters and evaluate their relationship with gestational age, birth weight, and postmenstrual age in prematurely born infants. Methods: The right eyes of 361 premature infants born before the 36th gestational week were evaluated. Birth weight, gestational week, and gender were recorded. An A-scan Biometer was used for obtaining axial measurements, including anterior chamber depth, lens thickness, vitreous length, and total axial length. Results: Gestational age and birth weight values ranged from 23 to 36 weeks and from 560 to 2,670 g, respectively. The mean gestational age and birth weight were 30.8 ± 2.8 weeks and 1,497.9 ± 483.6 g, respectively. During the first examination (4-5 weeks of postnatal age), birth weight and gestational age of the infants correlated significantly and positively with lens thickness, vitreous length, and axial length (r>0.5, p<0.001), but not with anterior chamber depth (r<0.5). Increased vitreous and axial lengths correlated significantly with increasing postmenstrual age of the infants (r=0.669, p<0.001; r=0.845, p<0.001, respectively). Conclusions: Lens thickness, vitreous length, and axial length, but not anterior chamber depth, were significantly correlated with birth weight and gestational age. All four parameters increased with increasing postmenstrual age, with higher correlations for vitreous and axial lengths than for anterior chamber depth and lens thickness. It was concluded that axial elongation resulted primarily from increasing posterior chamber length. .

RESUMO Objetivo: Medir os comprimentos axiais dos componentes oculares e avaliar a relação com a idade gestacional, peso ao nascer e idade pós-menstrual em crianças nascidas prematuramente. Método: O olho direito de 361 crianças prematuras, que nasceram com menos de 36 semanas de gestação, foram avaliados. O peso ao nascer, semanas de gestação e gênero foram registrados. Um biômetro A-scan foi utilizado para a obtenção das medidas axiais da profundidade da câmara anterior, espessura do cristalino, comprimento vítreo e comprimento axial total. Resultados: A idade gestacional e os valores de peso ao nascimento variaram de 23 a 36 semanas e de 560 a 2.670 g, respectivamente. A idade gestacional e o peso ao nascer foram 30,8 ± 2,8 semanas e 1.497,9 ± 483,6 g. Ao primeiro exame (4 a 5 semanas de idade pós-natal), o peso ao nascimento e a idade gestacional dos recém-nascidos apresentaram correlação positiva, estatisticamente significativa, com a espessura do cristalino, comprimento vítreo e comprimento axial total (r>0,5 p<0,001), mas não com a profundidade da câmara anterior (r<0,5). O alongamento de comprimento vítreo e do comprimento axial total se correlacionaram significativamente com o aumento da idade pós-menstrual dos lactentes (r=0,669; p<0,001 e r=0,845; p<0,001, respectivamente). Conclusões: A espessura do cristalino, o comprimento vítreo e o comprimento axial total, mas não profundidade da câmara anterior, foram significativamente correlacionados com o peso ao nascimento e com a idade gestacional. Todos os quatro componentes aumentaram com a idade pós-menstrual, apresentando correlações mais elevadas do comprimento vítreo e comprimento axial total do que da profundidade da câmara anterior e espessura do cristalino. Concluiu-se que o alongamento axial resultou principalmente do aumento do comprimento da câmara posterior. .

Estudio densitométrico del cristalino y su relación con el sistema LOCS III / Densitometric study of the crystalline lens and its relationship with the LOCS III system

Objetivo: determinar la dureza nuclear del cristalino clasificada por el Lens Opacities Classification System (LOCS III) y su relación con la densitometría del cristalino. Métodos: se realizó un estudio descriptivo, longitudinal y prospectivo en el Centro de Microcirugía Ocular del Instituto Cubano de Oftalmología Ramón Pando Ferrer, desde enero de 2011 hasta diciembre de 2011, en 290 pacientes diagnosticados con catarata y operados con la técnica de facoemulsificación por pre chop, más implante de lente intraocular. Resultados: los núcleos cristalineanos (N) clasificados del N1 al N6 aumentaron la densitometría del cristalino hasta un valor de 46,5 por ciento, con tiempo efectivo de facoemulsificación de 0,54 min relacionado a la dureza nuclear, al igual que las clasificadas de P2 a P5 donde la densitometría fue hasta 66,1 por ciento con valores de tiempo efectivo de facoemulsificación de 0,46 min. La edad media fue de 63,8 años de edad, se planificó una refracción esperada para -0,16 D, el equivalente esférico posoperatorio fue de 0,50 D y el astigmatismo medio inducido de -0,56 D. La mejor agudeza visual sin corrección mejoró a 0,81 en el posoperatorio y la corregida final fue de 0,96. Conclusiones: el estudio densitométrico del cristalino, como valor objetivo de su dureza, le permite al cirujano trazarse una estrategia quirúrgica adecuada en cada paciente para lograr una verdadera cirugía refractiva personalizada del cristalino y resultados visuales óptimos

Objective: To determine the nuclear hardness of the crystalline lens according to the Lens Opacities Classification System (LOCS III) and its relationship with the crystalline lens densitometry. Methods: A prospective, cross-sectional and descriptive study was conducted in 290 patients diagnosed with cataract and operated on by the prechop phacoemulsification technique plus intraocular lens implantation, at Ramon Pando Ferrer Cuban Institute of Ophthalmology from January to December, 2011. Results: The crystalline lens nuclei classified as N1 to N6 increased the lens crystalline densitometry up to 46.5 percent, with effective phacoemulsification time of 0.54min with respect to the .nucleus hardness; the densitometry value in the nuclei classified P2 to P5 rose to 66.1 percent where the effective phacoemulsification time was 0.46. The average patients' age was 63.8 years, the expected refraction was planned to be -0.16D, the postoperative spherical equivalent was 0.50 D and the mean induced astigmatism reached -0.56 D. The best uncorrected visual acuity improved by 0.81 in the postoperative period and the final corrected acuity was 0.96. Conclusions: The densitometric study of the crystalline lens, as concrete value of hardness, allows the surgeon to draw an adequate surgical strategy for each patient in order to make a real customized refractive surgery of the crystalline lens and to obtain the optimal visual results

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.

Efficacy of lower doses of vanadium in restoring altered glucose metabolism and antioxidant status in diabetic rat lenses.

Vanadium compounds are potent in controlling elevated blood glucose levels in experimentally induced diabetes. However the toxicity associated with vanadium limits its role as therapeutic agent for diabetic treatment. A vanadium compound sodium orthovanadate (SOV) was given to alloxan-induced diabetic Wistar rats in lower doses in combination with Trigonella foenum graecum, a well-known hypoglycemic agent used in traditional Indian medicines. The effect of this combination was studied on lens morphology and glucose metabolism in diabetic rats. Lens, an insulin-independent tissue, was found severely affected in diabetes showing visual signs of cataract. Alterations in the activities of glucose metabolizing enzymes (hexokinase, aldose reductase, sorbitol dehydrogenase, glucose-6-phosphate dehydrogenase) and antioxidant enzymes (glutathione peroxidase, glutathione reductase) besides the levels of related metabolites, [sorbitol, fructose, glucose, thiobarbituric acid reactive species (TBARS) and reduced glutathione (GSH)] were observed in the lenses from diabetic rats and diabetic rats treated with insulin (2 IU/day), SOV (0.6 mg/ml), T. f. graecum seed powder (TSP, 5%) and TSP (5%) in combination with lowered dose of vanadium SOV (0.2 mg/ml), for a period of 3 weeks. The activity of the enzymes, hexokinase, aldose reductase and sorbitol dehydrogenase was significantly increased whereas the activity of glucose-6-phosphate dehydrogenase, glutathione peroxidase and glutathione reductase decreased significantly in lenses from 3 week diabetic rats. Significant increase in accumulation of metabolites, sorbitol, fructose, glucose was found in diabetic lenses. TBARS measure of peroxidation increased whereas the levels of antioxidant GSH decreased significantly in diabetic condition. Insulin restored the levels of altered enzyme activities and metabolites almost to control levels. Sodium orthovanadate (0.6 mg/ml) and Trigonella administered separately to diabetic animals could partially reverse the diabetic changes, metabolic and morphological, while vanadate in lowered dose in combination with Trigonella was found to be the most effective in restoring the altered lens metabolism and morphological appearance in diabetes. It may be concluded that vanadate at lowered doses administered in combination with Trigonella was the most effective in controlling the altered glucose metabolism and antioxidant status in diabetic lenses, these being significant factors involved in the development of diabetic complications, that reflects in the reduced lens opacity.

Morphometry of the lens development in albino rat

This study analysed pattern of growth of the lens by measuring the lens surface area, circumference and diameters in relation to the eye ball in albino rat at ten stages, 12, 13, 14, 16, 18 and 20 days of embryonic development and 1, 7. 14 and 28 days of post-natal development. We used the recent technique DIAD [Digitizing and Image Analyzing Device] and runing the autocad program. Surface area of the lens increases during different stages of development and reachs its maximum percentage in relation to the eye ball during the 4[th] and 5[th] stages. Surface area of the lens at 10[th] stage is more than 60 folds than the 1[st] stage. Transverse diameter of the last stage is more than 8 times of the first stage. Anteroposterior diameter is nearly equal the transverse diameter up to the 5[th] stage then it declines. Significant age-related linear increas were found for all parameters

Anterior chamber depth and lens thickness in primary angle-closure glaucoma: a case-control study.

Anterior chamber depth and lens thickness have been considered as important biometric determinants in primary angle-closure glaucoma (PACG). In a tertiary care centre-based case-control study, 70 patients and equal number of controls were investigated to analyse the strength of association and predictability of anterior chamber depth (ACD) and lens thickness (LT) in the disease. Mean (+/- S.D.) ACD and LT in the cases and the controls were found to be 2.28 +/- 0.19, 2.87 +/- 0.10; 4.57 +/- 0.34 and 4.13 +/- 0.19 mm respectively. Two sample t test demonstrated statistically significant difference in the ACD and LT between the cases and the controls (Difference being -0.59, 0.44; 95% confidence interval of the difference: -0.64, -0.53 and 0.34, 0.53 respectively, P < 0.01). Logistic regression analysis demonstrated statistically significant protective effect of ACD over PACG (P < 0.01). The odds ratio corresponding to an increase of 0.01 mm in ACD and LT were computed as 0.83 and 1.11 respectively.

Ocular dimensions with aging in normal eyes

To quantify the dynamic changes taking place in the anterior segment, we measured the anterior chamber depth (ACD), lens thickness (LT) and their difference between sexes and age groups in normal eyes using contact ultrasonography and anterior chamber photography. There were 141 women (241 eyes) and 76 men (130 eyes) between the ages of 10 and 70 years. In normal eyes, the lens thickness was increased and the anterior chamber depth was decreased with aging in both sexes. The anterior chamber depth showed an accelerated decrease between the 4th and 5th decades in females and the ratio of anterior chamber depth to axial length was smaller in females than in males after the 5th decade. The results suggested that the prevalence of angle closure glaucoma will be increased in females after middle age.