Despite an association between increased ocular perfusion pressure (OPP) and glaucoma, increasing blood pressure in an effort to modulate OPP appears to offer no value for treating glaucoma, according to a study published in a 2010 issue of the American Journal of Ophthalmology. Caprioli and Coleman from the Jules Stein Eye Institute at the University of California, Los Angeles, conducted the study, which reviewed current literature and presented the findings of the Blood Flow in Glaucoma Discussion Group.
"There is currently no evidence that manipulation of blood pressure or blood flow improves outcomes in glaucoma," the authors wrote. "Although low OPP is now an established risk factor in glaucoma, is is not clear whether it is truly independent of the sum of 2 separate risk factor-high [intraocular pressure] and low blood pressure."
While in theory, controlling OPP via blood pressure may seem appealing, modulating OPP in practice is complicated by a range of factors, including the potential for inaccuracy in OPP measurements, the authors noted. OPP measured during a routine examination may vary significantly from a patients physiologic OPP and therefore may not accurately correlate with the perfusion of the optic nerve head.
The authors added that there is currently little evidence to identify which vascular beds are important in the development and prevention of glaucoma, and therapies not targeted to those beds could cause an unwarranted increase in overall pressure and an attendant increase in morbidity and mortality. "There is the possibility that improving optic nerve perfusion by diverting blood from elsewhere (such as retinal capillary beds) may have unforeseen adverse effects, " they wrote.
While future drugs developed to target specific pathways or receptors may offer hope for treatment of glaucoma via OPP modulation current evidence does not support such treatment. "Glaucoma is a heterogeneous group of related diseases," the authors noted. "There may be subgroups of patients in whom vascular factors are important, (but) those patients subgroups have not been well identified."
Monday, October 17, 2011
Wednesday, October 12, 2011
Decreasing the Risk of Vision Loss in Herpes Simplex Patients
The use of oral antiviral medications in patients with herpes simplex virus (HSV) appears to help decrease the risk of recurrence of epithelial keratitis, stromal keratitis, conjunctivitis, and blepharitis, and may decrease the risk of vision loss in these patients, according to a retrospective study conducted by Young et al from Mayo Clinic, Minnesota. The results of the study were published in a 2010 issue of the Archives of Ophthalmology.
In the study, researchers reviewed the outcomes of 394 residents of Olmsted County, Minnesota, diagnosed with ocular HSV from 1976 through 2007, and compared the frequency of recurrence and adverse outcomes such as vision loss or need for surgery, among patients treated prophylactically with oral antiviral medication and those who did not receive oral antiviral medication. According to their data, the authors found that patients who were not being treated prophylactically were
- 9.4 x more likely to have a recurrence of epithelial keratitis
- 8.4 x more likely to have a recurrence of stromal keratitis
- 34.5 x more likely to have a recurrence of blepharitis or conjunctivitis
Of the 20 patients included the study who experienced adverse outcomes, 17 were not being treated with oral antiviral medications immediately prior to the adverse event.
HSV is a common cause of corneal disease, and recurrence is relatively common. Following initial exposure and primary systemic infection, HSV establishes a latent infection in the trigeminal or other sensory ganglia, disease may recur in one or both eyes, with the risk of recurrence significantly increasing over time. The cumulative effect of these reactivations may lead to stromal inflammation or neurotrophic keratitis, resulting in scar of perforation, the authors noted.
"The results of this study suggest that oral antiviral prophylaxis should be considered for patients with frequent recurrences of corneal disease," the authors concluded. "Additionally, we recommend an evaluation of possible barriers preventing compliance with antiviral prophylaxis and a reassessment of the cost-effectiveness of long-term oral antiviral therapy."
In the study, researchers reviewed the outcomes of 394 residents of Olmsted County, Minnesota, diagnosed with ocular HSV from 1976 through 2007, and compared the frequency of recurrence and adverse outcomes such as vision loss or need for surgery, among patients treated prophylactically with oral antiviral medication and those who did not receive oral antiviral medication. According to their data, the authors found that patients who were not being treated prophylactically were
- 9.4 x more likely to have a recurrence of epithelial keratitis
- 8.4 x more likely to have a recurrence of stromal keratitis
- 34.5 x more likely to have a recurrence of blepharitis or conjunctivitis
Of the 20 patients included the study who experienced adverse outcomes, 17 were not being treated with oral antiviral medications immediately prior to the adverse event.
HSV is a common cause of corneal disease, and recurrence is relatively common. Following initial exposure and primary systemic infection, HSV establishes a latent infection in the trigeminal or other sensory ganglia, disease may recur in one or both eyes, with the risk of recurrence significantly increasing over time. The cumulative effect of these reactivations may lead to stromal inflammation or neurotrophic keratitis, resulting in scar of perforation, the authors noted.
"The results of this study suggest that oral antiviral prophylaxis should be considered for patients with frequent recurrences of corneal disease," the authors concluded. "Additionally, we recommend an evaluation of possible barriers preventing compliance with antiviral prophylaxis and a reassessment of the cost-effectiveness of long-term oral antiviral therapy."
Monday, October 3, 2011
10/3/11
Finding the Causes of Pediatric Cataracts
Although approximately 200,000 children worldwide are bilaterally blind from cataracts, the causes of the majority of cases remain undetermined, making prevention often problematic. A retrospective study of pediatric cataracts by Lim et al from the Hospital for Sick Children, Canada, indicates that, although the cause remains unclear in many instances, understanding associated and potential contributing factors can be a powerful tool in both treatment and diagnosis of the condition.
"Data on the characteristics of pediatric cataracts are useful for the purpose of diagnosis, genetic counseling, and selection of treatment options," the aauthors wrote in a 2010 issue of the American Journal of Ophthalmology. "Prevention strategies also require information about etiology."
The authors reviewed 1122 eyes of 778 consecutive patients suffering from cataract. About a third of syndrome-associated cataracts occurred in patients with Down syndrome. Posterior subcapsular cataract was the most common morphologic type, and more than half of all patients presented with unilateral cataracts. Almost 13% of patients examined had developed cataracts as the result of trauma, and almost 12% of cases had genetic origins. Although the most common systemic association involved diseases treated with steroids, about 58% had no clear etiology.
"Slightly over half of our patients had cataracts of unknown etiology despite examinations of their parents and siblings and, where indicated, laboratory investigations," the authors noted. "Idiopathic cataract is a diagnosis of exclusion. A metabolic and genetic examination tailored, with the assistance of a pediatrician, according to the medical and developmental history may be indicated when there are no other clear etiologic factors." The authors added that while steroid use is clearly established a relationship between the incidence of cataracts and the dosage or duration of steroid therapy."
Finding the Causes of Pediatric Cataracts
Although approximately 200,000 children worldwide are bilaterally blind from cataracts, the causes of the majority of cases remain undetermined, making prevention often problematic. A retrospective study of pediatric cataracts by Lim et al from the Hospital for Sick Children, Canada, indicates that, although the cause remains unclear in many instances, understanding associated and potential contributing factors can be a powerful tool in both treatment and diagnosis of the condition.
"Data on the characteristics of pediatric cataracts are useful for the purpose of diagnosis, genetic counseling, and selection of treatment options," the aauthors wrote in a 2010 issue of the American Journal of Ophthalmology. "Prevention strategies also require information about etiology."
The authors reviewed 1122 eyes of 778 consecutive patients suffering from cataract. About a third of syndrome-associated cataracts occurred in patients with Down syndrome. Posterior subcapsular cataract was the most common morphologic type, and more than half of all patients presented with unilateral cataracts. Almost 13% of patients examined had developed cataracts as the result of trauma, and almost 12% of cases had genetic origins. Although the most common systemic association involved diseases treated with steroids, about 58% had no clear etiology.
"Slightly over half of our patients had cataracts of unknown etiology despite examinations of their parents and siblings and, where indicated, laboratory investigations," the authors noted. "Idiopathic cataract is a diagnosis of exclusion. A metabolic and genetic examination tailored, with the assistance of a pediatrician, according to the medical and developmental history may be indicated when there are no other clear etiologic factors." The authors added that while steroid use is clearly established a relationship between the incidence of cataracts and the dosage or duration of steroid therapy."
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