Ocular Cataract Research Articles

Fluoroquinolones in animal health.

The fluoroquinolones are a series of synthetic antibacterial agents that are undergoing extensive investigation for both human and veterinary use in the treatment of a variety of bacterial infections. These agents work through the inhibition of DNA gyrase, interfering with the supercoiling of bacterial chromosomal material. As a result, these agents are rapidly bactericidal primarily against gram-negative bacteria, mycoplasma, and some gram-positive bacteria, with most having little to no activity against group D streptococci and obligate anaerobic bacteria. Resistance develops slowly and is almost always chromosomal and not plasmid-mediated. However, development of resistance to the fluoroquinolones and transfer of that resistance among animal and human pathogens have become a hotly debated issue among microbiologists. The fluoroquinolones are a current antimicrobial class whose use in veterinary medicine is being scrutinized. From a pharmacokinetic perspective, these agents are variably but well absorbed from the gastrointestinal tract and almost completely absorbed from parenteral injection sites, and they are well distributed to various tissues in the body. The fluoroquinolones are metabolized and renally excreted, with many of them having approximately equal excretion by the hepatic and the renal excretory systems. The primary toxicity observed at therapeutic doses involves the gastrointestinal system and phototoxicity, although at higher doses central nervous system toxicity and ocular cataracts are observed. Administration to immature animals may result in erosive arthropathies at weight-bearing joints, and administration of high doses to pregnant animals results in maternotoxicity and occasionally embryonic death. The fluoroquinolones are approved for indications such as urinary tract infections and soft tissue infections in dogs and cats and colibacillosis in poultry. Approval for bovine respiratory disease in the United States is being sought. Other indications for which the fluoroquinolones have been used in animal health include deep-seated infections, prostatitis, and other bacterial infections resistant to standard antimicrobial therapy.

Ocular toxicology.

This review of recent articles on ocular toxicology concentrates on undesirable effects on the eye induced by systemically used xenobiotics. These effects include the corticosteroid-induced glaucoma and cataracts (especially in children), chloroquine-induced heart block and retinopathy, its possible protection by platelet aggregating factor antagonists, oculopathy after intracarotid chemotherapy with nitrosyl-urea or cisplatin, ketoconazole-induced papilledema, cytarabine-induced photophobia, ethambutol HCl-induced visual deficits, psychotherapeutic-agent overdose-induced ocular bobbing, amiodarone-induced cataracts, and imipramine HCl-induced angle-closure glaucoma. Also reviewed are the role of hormone levels in diabetic retinopathy, the therapeutic use of clonidine for perioperative intraocular pressure spikes, the increase in ocular blood flow by pentoxifylline, and decrease by nicotine, the potential for the reduction in drop size of mydriatic medications, a theory for sulfonamide-induced myopia, and guidelines for animal models of ocular toxicity. No drug achieves ultimate efficacy or ultimate safety. Thus, the decision to employ a given therapy involves a physician's evaluation of its therapeutic index, the ratio between efficacy and toxicity.

Possible mode of seawater-adapting actions of growth hormone in salmonids

Formation of ocular cataracts after seawater (SW) exposure of yearling coho salmon has been studied in relation to the parr-smolt transformation. No ocular opacity was observed in fish in fresh water (FW). In February and March, survival rates 12 h after exposure to SW were 11 and 20%, respectively, and cataracts were observed in all survivors. Cataracts persisted even after prolonged adaptation to SW. In April, when yearling coho smolts migrate naturally to the sea, the incidence of cataracts decreased to 40% in the first week, none in the second and third weeks, and 14% in the last week of the month. Although no mortality in SW was seen from May to August, cataract incidence increased to 33% in May and 42% in June–August. The increase in cataract formation coincided with a decrease in SW adaptability.The time course of cataract appearance was studied in yearling masu salmon. In February, cataracts appeared 1 h after transfer to SW, and more than 80% of the fish showed cataracts after 3 h. When a lens of masu salmon was exposed to hypertonic salmon Ringer's solution, the transparent lens fibers became opaque within 1 h, indicating that cataracts may be induced by increased osmolality of the aqueous humor or by dehydration of the lens. Ocular opacity was limited to the area immediately below the lens epithelium around the suture line, where the tips of the cortical lens fibers meet at the center of the corneal (outer) side of the lens. The cataract seems to arise from structural damage to cortical fibers. The occurrence of cataracts after SW transfer may provide a simple and accurate method of evaluating the degree of smoltification of salmonids.

Reverse Mutation in Myotonic Dystrophy

Myotonic dystrophy is a multisystem disorder that is transmitted in an autosomal dominant fashion and is characterized by muscular weakness and atrophy, clinical and electromyographic evidence of myotonia, ocular cataract, and various other abnormalities, such as cardiac conduction disturbances, testicular atrophy in males, premature balding, increased risk from anesthesia, and mental retardation in cases with early onset1. It is the most common inherited muscular dystrophy of adulthood, with an incidence of approximately 1 per 7500 people. The clinical expression of myotonic dystrophy is variable, ranging from neonatal mortality to a complete absence of symptoms. Recently, the disorder has been . . .

Association of ocular cataracts with inhaled and oral steroid therapy during long-term treatment of asthma

Background: Posterior subcapsular cataracts (PSCs) have been reported to occur in some asthmatic patients treated with inhaled steroids, Methods: We studied the associations between the occurrence of PSCs and inhaled and oral steroid therapy in 48 adults in a cross-sectional survey by slit lamp, Accurate records of the patients' long-term usage of these drugs were available: 9,2 ± 5.2 years for inhaled steroid and 9.1 ± 9.3 years for prednisone (mean ± SD), Their current inhaled steroid dosage averaged 1.46 ± 0,85 mg/day (range, 0 to 3.2 mg/day). Results: Twenty-seven percent of the group had PSCs. The occurrence of PSCs correlated with the current daily dose and duration of prednisone use (p = 0.002 and p = 0,01, respectively), but not with the dose or duration of inhaled steroid treatment. As judged by multiple logistic regression analysis, neither the particular inhaled steroid drug used, nor its daily dose or cumulative dose, nor the additional nonsteroidal risk factors for PSCs also present in some of these patients contributed significantly to their risk of developing PSCs. Conclusions: The findings do not exclude the possibility that inhaled steroid therapy might lead to PSCs if a person has an exceptionally high inherent susceptibility. However, in the asthmatic population at large, the risk appears negligible, even if high doses of inhaled steroid are administered.

First- and second-trimester diagnosis of fetal ocular defects and associated anomalies: Report of eight cases

Ocular cataract, hypertelorism, hypotelorism, anophthalmos, and microphthalmos are rare malformations commonly associated with other fetal anomalies. Previously, ocular malformations were detected only after mid-gestation. Transvaginal sonography allows the detection of many structural fetal anomalies. We describe the case reports of eight ocular anomalies among 1600 fetal screenings by transvaginal sonography at 12-18 weeks' gestation. Severe cataract was correctly diagnosed by transvaginal sonography. However, transvaginal sonography failed to detect moderate cataract in a case of repeat cataract in a subsequent gestation. Anophthalmia may sometimes be secondary to a degenerative process in middle and late pregnancy. In five of the eight described cases, the eye malformations were associated with defects of the central nervous system.

Therapeutic Dilemmas in External Ocular Diseases

Three ocular conditions continue to pose therapeutic dilemmas for the practising clinician. Acanthamoeba keratitis, which presents with ocular pain, redness, tearing, photophobia and lid oedema, should be considered in any chronic, progressive corneal ulceration that is unresponsive to conventional treatment. Although the best treatment for this infection has yet to be defined, surgery should be reserved for those patients with progressive destructive disease or corneal penetration. Topical antibiotics and oral ketoconazole may be beneficial, as may surgical debridement in conjunction with topical antibiotic-antifungal combinations. However, since more than two-thirds of reported cases involve contact lens wearers, patients should be instructed as to the importance of regular lens care regimens. Giant papillary conjunctivitis occurs more frequently in soft contact lens wearers than in those wearing hard lenses, but may also occur in association with ocular prostheses, cataract surgery and corneal transplants. Symptoms of increased lens awareness, mucus accumulation, itching and blurred vision occur. Stopping use of contact lenses usually improves or eliminates these irritating effects, but is not always practical. Thus, resolution or improvement of symptoms while the patient continues to wear contact lenses is desirable, making lens hygiene essential in treatment. Pharmacological treatment includes the use of topical corticosteroids and agents that stabilise mast cells, such as cromolyn sodium. The dry eye syndrome can occur alone or as a part of Sjögren's syndrome. The irritation, redness, and other symptoms associated with ocular dryness are usually treated by preparations of either mucomimetics, polyvinyl alcohol or cellulose derivatives, which provide moisture and prevent evaporation from the surface of the eye.

Late effects of total body irradiation and cytostatic preparative regimen for bone marrow transplantation in children with hematological malignancies

Twenty-seven children, surviving disease-free for more than 1 year after allogeneic bone marrow transplantation (BMT) for hematological malignancy were evaluated for the long-term effects on endocrine function, sexual development, physical growth, appearance of ocular cataract and psychological sequelae. The growth rate was not decelerated in the prepubertal period in children not affected by chronic graft-versus-host (GVH) disease and without previous cranial irradiation. Development of sexual characteristics was delayed in 4 relevant cases. Thyroid function was not adversely affected, gonadal function was impaired in girls, transplanted after menarche, ocular cataract developed in all cases, irradiated without shielding of the eyes after 4 years. Psychologically, children after BMT had an advantageous social development.

Health Effects of Ozone Depletion

The problem of ozone depletion has recently become a topic of major concern. What was once a vague, theoretical hypothesis that artificial chlorofluorocarbon compounds could accumulate in the stratosphere and break down ozone molecules is an imminent reality. A decrease in the concentration of stratospheric ozone would increase the amount of ultraviolet radiation in ambient sunlight. In addition to altering plant and aquatic life in unpredictable ways, increiased ultraviolet radiation will adversely affect human health. The incidence of various types of skin cancers will increase, as will the rate of deaths from skin cancer. In addition, there will be an increase in the occurrence of certain types of ocular cataracts. The most recently described effect of ultraviolet radiation on a biologic system is its ability to alter the immune system in experimental animals and humans. Although much is known about the immunologic effects of ultraviolet radiation, particularly in animal models, little information is available on its potential to decrease host resistance to infectious diseases. This is an important topic that needs to be addressed in order for us to understand fully the consequences of ozone depletion for human health.

The ontogeny of gamma-crystallin mRNAs in CatFraser mice.

SummaryMice which are either homozygous or heterozygous for the CatFraser mutation have ocular cataracts accompanied by selective reduction of the γ-crystallins, a homologous family of proteins present in the lens and encoded by a family of tightly linked genes. We measured the concentrations of four different mRNAs, each encoding a different γ-crystallin, in the lenses of homozygous CatFraser mice and in normal controls at various stages of development by preparing Northern blots from lens RNA, probing with RNAs complementary to each of the four messages and densitometry of the bands thus generated. The results show that, for each of these messages, the ontogenetic patterns observed in normal mice are retained in the mutant, but at much lower concentrations.

The murine cataractogenic mutation, Cat Fraser, segregates independently of the gamma crystallin genes.

SummaryThe murine mutation, Cat Fraser (CatFr), causes dominantly inherited ocular cataracts. Lenses of adult mice bearing this mutation contain reduced amounts of all seven γ-crystallin proteins and their corresponding transcripts. Levels of other lens proteins and transcripts appear normal and no extra-ocular effects of the mutation have been observed. The selective effect of this mutation on the γ-crystallins is consistent with the possibility that the site at which it occurs is involved in the coordinated regulation of the family of genes which encodes them. We have shown that several restriction fragment length polymorphisms in the γ-crystallin genes segregate independently of the CatFr mutation. Therefore, despite its selective effect on the expression of the γ-crystallin genes, the mutation is not linked to them. This observation rules out the possibility that the mutation is in a cis-acting regulatory site.

Ocular cataract and seawater adaptation in salmonids

Formation of ocular cataracts after seawater (SW) exposure of yearling coho salmon has been studied in relation to the parr-smolt transformation. No ocular opacity was observed in fish in fresh water (FW). In February and March, survival rates 12 h after exposure to SW were 11 and 20%, respectively, and cataracts were observed in all survivors. Cataracts persisted even after prolonged adaptation to SW. In April, when yearling coho smolts migrate naturally to the sea, the incidence of cataracts decreased to 40% in the first week, none in the second and third weeks, and 14% in the last week of the month. Although no mortality in SW was seen from May to August, cataract incidence increased to 33% in May and 42% in June–August. The increase in cataract formation coincided with a decrease in SW adaptability. The time course of cataract appearance was studied in yearling masu salmon. In February, cataracts appeared 1 h after transfer to SW, and more than 80% of the fish showed cataracts after 3 h. When a lens of masu salmon was exposed to hypertonic salmon Ringer's solution, the transparent lens fibers became opaque within 1 h, indicating that cataracts may be induced by increased osmolality of the aqueous humor or by dehydration of the lens. Ocular opacity was limited to the area immediately below the lens epithelium around the suture line, where the tips of the cortical lens fibers meet at the center of the corneal (outer) side of the lens. The cataract seems to arise from structural damage to cortical fibers. The occurrence of cataracts after SW transfer may provide a simple and accurate method of evaluating the degree of smoltification of salmonids.

Bupivacaine and lignocaine for ophthalmic surgery.

Bupivacaine 0.5% when used as a local anaesthetic for ocular cataract surgery does not give absolute ocular akinesia but provides adequate and prolonged pain relief. In comparison lignocaine provides good ocular akinesia at operation but pain relief is short lived. The mixture of the two local anaesthetics in equal volumes eliminated the disadvantages of their individual use.

Recent advances in ocular cataract research

Cataracts account for blindness in 17 million people worldwide. Prevention and treatment of opacity of the lens requires complete understanding of lens biochemistry and structure. Anthony Cerami and James Crabbe discuss the evidence for the various mechanisms of cataract formation that have been proposed, based on results from experimental animals. For pharmacologists there are two implications: firstly, cataracts can result as undesirable side-effects of drugs; and secondly, there is now potential for the rational development of drugs which interfere with cataract formation. Inhibitors of aldose reductase are already available.

Ocular cataract in yearling coho salmon in sea water

Ocular cataract in yearling coho salmon in sea water

Survey of Ocular Cataracts in Radium Dial Workers

Survey of Ocular Cataracts in Radium Dial Workers

Survey of Ocular Cataracts in Radium Dial Workers

Survey of Ocular Cataracts in Radium Dial Workers

Survey of ocular cataracts in radium dial workers.

A survey of the medical records of 813 female radium dial workers first exposed to radium before 1930 yielded reports of 119 cataracts in the group whose radium body burden had been measured at least once. After dividing the subjects into high and low dose groups, the data were analyzed according to latency (time between first employment and first diagnosis of cataract), duration of employment and age at first exposure. Duration of employment and age at employment showed no significant correlation with dose. Latency, however, showed a significant negative correlation with dose. Since radiation cataracts tend to occur earlier than so-called senile cataracts, these preliminary data suggest the need for further investigation.

Multiple changes in lens protein composition associated with Cat Fr gene in the mouse.

SUMMARYThe ocular cataracts produced by the dominant CatFr gene in the mouse, Mus musculus, are associated with quantitative changes in the lens proteins (crystallins). The three classes of crystallin are affected differentially in homozygotes. Heterozygotes show a smaller effect. The quantitative levels of crystallin subunits are also affected and these changes are different for each subunit. The overall loss in protein is not readily explicable hi terms of a generalised leakage or a general tendency to insolubilisation. Possible mechanisms for the action of the gene are suggested.

Urgent Treatment of Face and Jaw Injuries

Electrical burns are classified as either high voltage (1000 volts and higher) or low voltage (< 1000 volts). The typical injury with a high-voltage electrical contact is one where subcutaneous fat, muscles, and even bones are injured. Lower voltages may have lesser injuries. The electrical current has the potential to injure via three mechanisms: injury caused by current flow, an arc injury as the current passes from source to an object, and a flame injury caused by ignition of material in the local environment. Different tissues also have different resistance to the conduction of electricity. Voltage, current (amperage), type of current (alternating or direct), path of current flow across the body, duration of contact, and individual susceptibility all determine what final injury will occur. Devitalized tissue must be evaluated and debrided. Ocular cataracts may develop over time following electrical injury. Lightning strikes may conduct millions of volts of electricity, yet the effects can range from minimal cutaneous injuries to significant injury comparable to a high-voltage industrial accident. Lightning strikes commonly result in cardiorespiratory arrest, for which CPR is effective when begun promptly. Neurologic complications from electrical and lightning injuries are highly variable and may present early or late (up to 2 years) after the injury. The prognosis for electricity-related neurologic injuries is generally better than for other types of traumatic causes, suggesting a conservative approach with serial neurologic examinations after an initial CT scan to rule out correctable causes. One of the most common complications of electrical injury is a cardiac dysrhythmia. Because of the potential for large volumes of muscle loss and the release of myoglobin, the presence of heme pigments in the urine must be evaluated promptly. Presence of these products of breakdown of myoglobin and hemoglobin puts the injured at risk for acute renal failure and must be treated. The exact mechanism of nerve injury has not been explained, but both direct injury by electrical current overload or a vascular cause receive the most attention. Because electrical injuries carry both externally visible cutaneous injuries and possible hidden musculoskeletal damage, conventional burn resuscitation formulas based on body surface area injured may not provide enough fluid to maintain urine output. Damaged muscle resulting in swelling within the investing fascia of an extremity may result in compartment syndromes, requiring further attention. If myoglobin has been detected in the urine, treatment is aggressive volume resuscitation and possibly alkalinization of the urine or mannitol is given IV push to minimize pigment precipitation in the renal tubules. Approximately 15% of electrical burn victims also sustain traumatic injuries. This is because of falls from height or being thrown against an object. The tetanic contractions that result from exposure to electrical injury cause imbalance in flexor versus extensor muscles, with the flexor groups being stronger. Not only is the victim unable to release from the electrical contact, but they are at risk for fracture of bones from this prolonged muscular contracture. Neurologic and psychological symptoms were the most common sequelae of electrical and lightning injuries. Many of these symptoms are nonspecific, and they often do not appear until several months after the injury. A full neurologic examination must be performed on admission, documenting initial presentation and at any change in symptoms. Electrical injuries can have devastating consequences. Prevention of electrical injuries is clearly the preferable strategy for treatment.