Comparison of capsular opacification and refractive status after placement of three different intraocular lens implants following phacoemulsification and aspiration of cataracts in dogs

Objective  To evaluate the effect of lens design and biomaterial on formation of posterior capsular opacification (PCO) and refractive correction.
Animals studied  Sixty dogs undergoing bilateral phacoemulsification for mature or diabetic cataracts.
Procedures  One randomly selected eye received a rounded edge 41D polymethyl-methacrylate (PMMA) intraocular replacement lens (IOL) and the contralateral eye received either a squared edge 41D hydrophilic acrylic IOL ( n  = 35) or a squared edge 40D hydrophobic acrylic IOL ( n  = 25). At the (mean = 79 day) reexamination period, PCO was graded using direct slit-lamp observation and by masked observer evaluation of digital images of the IOLs. Streak retinoscopy and B-mode ultrasound were performed at this period.
Results  The PCO score via direct slit-lamp was significantly lower for the hydrophilic acrylic IOL when compared to the PMMA IOL. Masked observer evaluation of digital images revealed that the acrylic IOLs had lower but generally not statistically significant PCO scores than the PMMA IOLs. Streak retinoscopy showed that the PMMA IOL was significantly closer to emmetropia (+0.44 D) when compared to either the hydrophilic acrylic (+0.96 D) or the hydrophobic acrylic (+1.2 D) IOLs. B-mode ultrasonography revealed the center of the hydrophilic acrylic IOL is 0.31 mm closer to the retina and the center of the hydrophobic acrylic IOL is 0.63 mm further from the retina when compared to the center of the PMMA to retina distance.
Conclusions  Square edged foldable acrylic IOLs show a predisposition towards generating slightly less PCO than round edged PMMA IOLs in the early postoperative period, however, both acrylic IOLs had greater persistent hyperopia than the PMMA IOLs.     

Antioxidant profile of cataractous English Cocker Spaniels

Cataracts have been attributed to oxidative injury in proteins and lipids. Primary defenses that directly protect the lens against oxidative damage include small molecule antioxidants (vitamin C, vitamin E, glutathione and carotenoids) and antioxidant enzymes (superoxide dismutase, catalase, and the glutathione enzyme systems – glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase). In humans, low plasmatic levels of vitamin C, vitamin E and carotenoids have been associated with a high risk of senile cataracts. Dogs are more prone to develop cataracts. A decrease in antioxidant defenses could be responsible for increased lens oxidation and cataract development. In this study we report the levels of erythrocytic enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glucose-6-phosphate dehydrogenase) and plasma vitamin C as well as malondialdehyde, in normal and cataractous English Cocker Spaniel dogs. Plasma vitamin C levels were consistently lower in cataractous dogs (20.17 μ m  ± 8.2 μ m ) when compared with normal dogs (24.1 μ m  ± 9.4 μ m ). These results indicate a possibly decreased synthesis in vitamin C, leading to lower aqueous humor levels of this vitamin. Considering that vitamin C levels in the aqueous humor may be responsible for lens antioxidant maintenance, and that these levels are obtained from plasma secretion through the ciliary epithelium, decreased plasma levels may indicate a decrease in the antioxidant capacity of the aqueous humor.     

Immunohistochemical analysis of lens epithelial-derived membranes following cataract extraction in the dog

The objective of the study was to characterize the morphologic and immunohistochemical features of lens epithelial-derived proliferative membranes from the anterior segment of canine globes. These features were correlated with those previously identified for diseases resulting from lens epithelial cell (LEC) proliferation including posterior capsular opacification, traumatic subcapsular cataract, and subcapsular plaques associated with hypermature cataracts. Sixteen canine globes were removed as a result of glaucoma or other complications following cataract extraction. Light microscopic and immunohistochemical analysis was performed on sections from formalin-fixed, paraffin-embedded globes. The tissues were stained with a variety of antibodies for cellular markers for LECs, growth factors or other cellular constituents relevant to cellular metaplasia and proliferation. The membranes were composed of monolayers or multilayers of spindle-shaped cells on the external surfaces of the anterior and posterior lens capsule, ciliary processes, iris leaflets, and iridocorneal angle, and they could be seen extending from an obvious monolayer of LEC within the capsular sac. Variably, scattered pigment cells, presumably of uveal origin, were concurrently present. Cellular components of the membranes stained positive for vimentin, transforming growth factor-beta, basic fibroblast growth factor, and smooth muscle actin. An amorphous eosinophilic extracellular matrix consisting predominately of collagen was associated with the membranes. Proliferative anterior segment membranes following cataract surgery were morphologically and immunohistochemically similar to cellular and matrix components of posterior capsular opacification and capsular plaques seen with hypermature cataracts, both of which result from metaplasia and proliferation of LEC. The presence of these LEC-derived membranes in association with secondary glaucoma suggests that exuberant proliferation of LEC outside the confines of the lens capsular sac may cause pathologic alterations in the eye following cataract surgery in the dog.     

Detection of anti-lens crystallin antibody in dogs with and without cataracts

Objective To determine if antilens crystallin (ALC) serum and aqueous humor antibodies were present in normal dogs and dogs with cataracts, whether antibody incidence varied with stage of cataract, and whether antibody titer had a relationship to the presence of lens‐induced uveitis. Methods Serum and aqueous humor samples were obtained from normal dogs and dogs with cataracts. Lens crystallin was separated by SDS‐polyacrylamide gel electrophoresis (SDS‐PAGE), and antilens crystallin antibodies were detected by Western immunoblot analysis. An indirect ELISA using crystallin protein as antigen was also used to detect antilens crystallin antibodies in serum and aqueous humor. Test groups included normal, incipient, immature, mature, hypermature and diabetic cataract. Results SDS‐PAGE identified bands with molecular weights of lens crystallin subunits. Western immunoblotting demonstrated reaction between canine serum and these protein bands. The five canine serum samples that reacted with crystallin subunits on Western blots had corresponding reactivity on the ELISA. All aqueous humor samples (30) were negative. Serum ALC antibodies were detected in 59.3% (16/27) of controls, 66.7% (16/24) of incipients, 50.0% (10/20) of immatures, 37.9% (11/29) of matures, 28.6% (6/21) of hypermatures, and 26.7% (4/15) of diabetics. Serum ALC antibodies were detected in 43.1% (47/109) of all cataract samples. There was a statistically significant negative association between the presence (P = 0.004) and maturity (P = 0.004) of cataract and presence of ALC serum antibodies. In the immature and hypermature cataract groups, there was a statistically significant negative association between ALC serum antibody titer and severity of uveitis (95% confidence interval). Conclusions There is a negative association between the presence (P = 0.004) and maturity (P = 0.004) of cataract and presence of ALC serum antibodies.     

Phacoemulsification and acryl foldable intraocular lens implantation in dogs: 32 cases

This study evaluated the surgical outcome and complications of phacoemulsification and the implantation of an acryl foldable intraocular lens (IOL) with a squared edge in dogs with cataracts. Thirty-two eyes from 26 dogs were examined. The mean follow up period was 75.9 days ranging from 23 to 226 days. The complications after phacoemulsification were posterior capsular opacity (PCO) around the IOL (n = 11), ocular hypertension (n = 4), focal posterior synechia (n = 4), hyphema (n = 3) and corneal ulcer (n = 2). The complications associated with the IOL were decenteration of the optic (n = 2) and ventral haptic displacement (n = 1). Most cases of PCO were found only around the margin of the IOL, and all eyes had vision during the observation period. In conclusion, the implantation of an acryl-foldable lens with a squared edge at the time of phacoemulsification is an effective method for preserving the central visual field of dogs with cataract.     

The incidence of posterior capsule disruption during phacoemulsification and associated postoperative complication rates in dogs: 244 eyes (1995-2002)

OBJECTIVE: The objective of this retrospective study was to report the incidence of posterior capsule disruption during routine phacoemulsification and to document the postoperative outcomes and complications in eyes with posterior capsule disruption compared with eyes with intact posterior capsules. PROCEDURES: Records of 143 dogs (244 eyes) were reviewed. Data collected included whether the posterior capsule was disrupted, whether the disruption was planned or accidental, whether an intraocular lens was implanted, and visual outcome. Records were reviewed for postoperative complications. Intraocular lens implantation rates, complication rates, and visual outcomes were compared between intact and disrupted posterior capsule groups using Chi-square analyses. RESULTS: The posterior capsule was disrupted in 33/244 eyes (14%). Planned capsulotomies accounted for 36% of the disruptions. Intraocular lenses were implanted in 76% of eyes without a disruption of the posterior capsule and in 31% of eyes with a posterior capsule disruption. Intraocular lenses were more likely to be implanted in eyes with a planned disruption of the posterior capsule (7/12; 58%) than in eyes with an accidental disruption (3/20; 15%). There were no significant differences in postoperative complications or visual outcome between eyes with posterior capsule disruption and those without. CONCLUSIONS: The most significant complication of posterior capsule disruption during phacoemulsification is the inability to implant an intraocular lens. Intraocular lenses are more likely to be placed in eyes with intentional disruptions of the posterior capsule than those with accidental ruptures.     

Secondary glaucomas in the dog in North America

OBJECTIVE: To determine the prevalence of secondary glaucomas in dogs associated with cataract formation, lens luxation or displacement, cataract surgery, uveitis, hyphema and intraocular neoplasia. METHODS: Information was obtained from the Veterinary Medical Data Base (VMDB) from all veterinary medical teaching hospitals in North America from March 1964 to March 2003. Secondary glaucomas were diagnosed at the same examination or after the primary diagnosis was made, and included those associated with cataract formation, lens luxation, cataract surgery, uveitis of unknown cause, hyphema of unknown cause, and intraocular neoplasia. The data were evaluated by decade, breed, gender and age of presentation. RESULTS: A total of 1 592 831 dogs were presented, and 9695 canine secondary glaucomas. Secondary glaucoma associated with cataract formation represented 81% of all the canine secondary glaucomas. Breeds (n = 7890 dogs) predisposed to secondary glaucoma and cataracts had an overall prevalence of 0.5%, but nearly 20% of all the cataractous dogs developed secondary glaucoma in at least one eye. For the years 1994-2003, these breeds included the American Cocker Spaniel; Boston Terrier; Toy, Miniature and Standard Poodle; English Springer Spaniel; Bichon Frise; and Labrador Retriever. The other forms of secondary glaucoma occurred less frequently, and included those glaucomas with lens luxation or displacement (779 dogs; 12.0%), postcataract surgery (528 dogs; 5.1%), with uveitis from unknown cause (399 dogs; 7.1%), with hyphema from unknown cause (117 dogs; 7.3%), and with intraocular neoplasia (19 dogs; 3.5%). The risk of the secondary glaucomas from 1984 to 2002 was highest after the intracapsular lens extraction (ICLE), less in the extracapsular technique (ECLE), and lowest for the phacoemulsification/phacofragmentation method. CONCLUSION: Prevalence of the canine secondary glaucomas ranges from 0.25% (1964-1973), 0.46% (1974-1983), 0.79% (1984-1993), to 0.80% (1994-2003) and are as frequent as the primary or breed-related glaucomas during these same time periods.     

智能手机实现虚拟角规的原理与设计

分析了利用智能手机摄像头实现虚拟角规测树功能的原理,讨论了实像尺寸偏差和虚拟角规缺口的关系,给出了计算虚拟角规缺口在摄像头中的实像公式,并结合智能手机中的加速度传感器设计了虚拟角规自动改平功能,为开发智能手机在林业行业中的应用进行了有意尝试。     

软性接触镜清洗液的研制及其质量定量检测方法的建立

本文报道了0.3％AES清洗液的研制经过。实验测定了其溶解变性蛋白的能力和清除油污的能力,并与其它清洗液进行了比较;观察了其清除模型软镜蛋白(脂质)沉积物的能力;测定了其与软镜的相容性;进行了兔眼刺激性实验和微生物学检查;测定了其各项物理指标并观察了其稳定性。实验证明该清洗液能迅速有效地清除软镜沉积物,性能优越,对镜片和兔眼无损害,符合国家药典规定的眼药水标准。讨论了清洗液诸成分的药理作用及清洗机理,对其效能的定量测定方法作了估计。     

Dietary histidine affects lens protein turnover and synthesis of N-acetylhistidine in Atlantic salmon (Salmo salar L.) undergoing parr–smolt transformation

This study was conducted to investigate protein synthesis rates and metabolism of histidine (His)‐derivatives in lenses of Atlantic salmon (Salmo salar L.) of different dietary His background during parr–smolt transformation. Two populations of Atlantic salmon parr of equal origin were established in freshwater (FW), 3 months prior to transfer to seawater (SW). The populations were fed either a control diet (CD) containing 8.9 g kg^?1 His or the same diet added crystalline His to a total level of 14.2 g kg^?1 (HD). On the basis of these two populations, ¹⁴C His force‐feeding studies were performed; in FW 3 weeks prior to sea transfer and in SW 6 weeks after transfer. The studies were conducted by force‐feeding the respective diets enriched with ¹⁴C labelled His, with subsequent measurements of incorporation of ¹⁴C His into lens free amino acid pool, as well as into lens proteins and other free His pool fractions. The latter included the major lens imidazole N‐acetylhistidine (NAH). Lens concentrations of His and NAH were clearly influenced by dietary His history, both in parr and smolt. The lens His and NAH concentrations in the CD population were considerably lower in SW than in FW, while in the HD group the His level was equal and the NAH level 50% higher in SW than in FW. Fractional synthesis rate for NAH, K_{S (NAH)}, in FW was 8.2 and 4.2 μmol g^?1 day^?1 for fish in the CD and HD populations, respectively. The corresponding K_{S (NAH)} values in SW were 5.1 and 33.0 μmol g^?1 day^?1. Our data show that free His is rapidly converted to NAH in the lens, and that NAH seems to have a very high turnover, especially in salmon reared in SW. Fractional synthesis rate for lens proteins, K_{S (PROTEIN)}, ranged between 1.8 and 17.3% day^?1 (182 and 2791 μg g^?1 day^?1, respectively), and was generally higher in SW than in FW (P < 0.01). In SW, K_{S (PROTEIN)} was highest in fish in the HD population (P < 0.05), whereas lens protein retention in the HD group was significantly lower than the CD group (P = 0.01). In a second model assuming that His from lens NAH is available for protein synthesis, calculated values of K_{S (PROTEIN)} ranged between 0.17% day^?1 (17.6 μg g^?1 day^?1) and 0.48% day^?1 (70.2 μg g^?1 day^?1). Cataract scores recorded in the His populations at a later point (day 204), showed that the CD fish had significantly higher mean cataract scores than individuals in the HD population (P < 0.01), confirming that low levels of lens His and NAH are associated with cataract development.