Volume 7, Number 42
Monday, October 22, 2007



In this issue: (click heading to view article)
Topical Glaucoma Therapy as a Risk Factor for Nasolacrimal Duct Obstruction
Haplotypes Protective Against AMD
Nuclear Cataract and Myopic Shift in Refraction
Heritable Skeletal Disorders Associated with Significant Ocular Findings
Briefly











Topical Glaucoma Therapy as a Risk Factor for Nasolacrimal Duct Obstruction

In a retrospective comparative study, researchers at Israel's Rambam Medical Center investigated a possible association between primary open-angle glaucoma (POAG) and primary acquired nasolacrimal duct obstruction (PANDO).

The study group consisted of 209 consecutive eyes (178 patients) whose lacrimal system had PANDO in patients older than 50 years during the 10-year study. The control group included 183 consecutive eyes (183 patients) that underwent cataract surgery during the same period. Main outcome measures were prevalence of POAG in study and control groups and the effect of topical glaucoma therapy use profile on PANDO prevalence. Medical records of all patients included in the study were reviewed. Data collected included demographic details and history and characteristics of POAG treatment.

The prevalence of POAG in the PANDO group (23 percent) was significantly higher than that of the control group (6 percent). The average history of POAG was longer in the PANDO group (14.10 +/- 5.59 years) compared with that of the control group (9.55 +/- 7.23 years). The average number of topical glaucoma therapy drugs per glaucomatous eye in the PANDO group (1.58 +/- 0.92) was significantly higher than that of the control group (0.73 +/- 0.90). Bilateral nasolacrimal duct obstruction was more common among glaucoma patients in the PANDO group (38.23 percent) than in non-glaucomatous patients in the same group (11.80 percent). A significantly higher percentage of glaucoma patients in the PANDO group (69 percent) were treated with timolol, compared with glaucoma patients in the control group (18 percent).

Based on these results, the authors suggest that chronic use of timolol-containing topical glaucoma therapy preparations in glaucoma patients may be associated with an increased risk for nasolacrimal duct obstruction. They stress, however, that large-scale prospective studies are needed to confirm such an association.


SOURCE: Seider N, Miller B, Beiran I. Topical glaucoma therapy as a risk factor for nasolacrimal duct obstruction. Am J Ophthalmol 2007; Oct 1 [Epub ahead of print]. 		Table of Contents











Haplotypes Protective Against AMD

The risk of age-related macular degeneration imparted by carrying the Y402H variant in the complement factor H (CFH) gene on chromosome 1 is well-known; however, recent evidence suggests the existence of protective haplotypes spanning CFH. Investigators at Vanderbilt University's Center for Human Genetics Research, the Center for Human Genetics at Duke University Medical Center and the Miami Institute for Human Genomics used the haplo.stats program to test whether these protective haplotypes exist, after adjusting for age in 584 sporadic cases and 248 control samples.

The researchers used logistic regression modeling and likelihood ratio tests to investigate an interaction between a particular haplotype and smoking status. The haplotype (HBAT) option of the family-based association test (FBAT) program was used to confirm the associations in an independent dataset of 201 families.

Two protective (P) haplotypes in a family-based dataset were identified for the first time. Age-adjusted score statistics provided support for these protective haplotypes in the case-control dataset. Results also showed tentative evidence of an interaction between one of the protective haplotypes and cigarette smoking.

The authors of the study believe that replication of the association between the protective haplotypes and decreased AMD susceptibility provides increased evidence that these associations have biological meaning. The suggestion of a haplotype-smoking interaction adds to the growing body of evidence that smoking is an important environmental covariate in AMD and that it should be considered in genetic studies. They believe that identifying the protective variant(s) carried within these haplotypes is critical for understanding the etiology of AMD.

SOURCE: Spencer KL, Hauser MA, Olson LM, et al. Haplotypes spanning the complement factor H gene are protective against age-related macular degeneration. Invest Ophthalmol Vis Sci 2007;48(9):4277-83.		 Table of Contents






Nuclear Cataract and Myopic Shift in Refraction

Nuclear cataract is thought to cause a myopic shift in refraction in older persons. Investigators at Australia's Centre for Vision Research, Sydney, tested this hypothesis in a population-based cross-sectional study by assessing the correlation of nuclear opacity with spherical equivalent refraction (SER) in an older population.

A total of 3,654 participants aged 49 years or older were examined in the Blue Mountains Eye Study (BMES) from 1992 to 1994. Eye examinations included subjective refraction and lens photographs. Physicians assessed nuclear opacity against four standard slit-lamp lens photographs using the Wisconsin Cataract Grading System. They defined nuclear cataract as opacity level 4 or higher.

Participants without nuclear cataract had an annual mean hyperopic shift of 0.05 diopters. In those with nuclear cataract, this hyperopic shift disappeared. A myopic refractive shift occurred only in persons with nuclear opacity levels of 4 or higher. The results document the contribution of nuclear cataract to the mild myopic shift that neutralizes the age-related hyperopic shift occurring in older persons.

SOURCE: Samarawickrama C, Wang JJ, Burlutsky G, et al. Nuclear cataract and myopic shift in refraction. Am J Ophthalmol 2007;144(3):457-9.		 Table of Contents






Heritable Skeletal Disorders Associated with Significant Ocular Findings

The type II collagenopathies are a phenotypically diverse group of genetic skeletal disorders caused by a mutation in the gene coding for Type II collagen. Reports published before the causative mutations were discovered suggest that heritable bone dysplasias with skeletal malformations may be associated with a vitreoretinopathy.

Researchers conducted a retrospective notes search of patients with a molecularly characterized Type II collagenopathy chondrodysplasia who had been examined in the Vitreoretinal Service at Cambridge University Hospital, England. Thirteen of 14 patients had a highly abnormal vitreous appearance. One patient, age 11 years, presented with a total retinal detachment. Two other children, aged 2 and 4 years, had bilateral flat multiple retinal tears on presentation. Ten out of 12 patients refracted were myopic. Two patients had asymptomatic lens opacities, one associated with bilateral inferiorly subluxed lenses and the other with a zonule and lens coloboma.

The investigators concluded that heritable skeletal disorders resulting from a mutation in the gene coding for Type II collagen are associated with abnormal vitreous, myopia and peripheral cataract with lens subluxation. In bone dysplasias resulting from a defect of Type II collagen, there is likely to be a high risk of retinal detachment with a propensity for retinal tears at a young age.

SOURCE: Meredith SP, Richards AJ, Bearcroft P, et al. Significant ocular findings are a feature of heritable bone dysplasias resulting from defects in type II collagen. Br J Ophthalmol 2007;91(9):1148-51.		 Table of Contents





BRIEFLY
  • LIMITING REFINED CARBOHYDRATES MAY STALL AMD PROGRESSION. Limiting the amount of carbohydrates in the diet may help slow the progression of age-related macular degeneration (AMD), according to a recent study by researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. The study, which appears in the October issue of the American Journal of Clinical Nutrition, builds on a recent analysis that found that men and women older than 55 years who consumed diets with higher-than-average dietary glycemic index foods appeared to have an increased risk both for early and later stages of AMD. Dietary glycemic index determines how quickly carbohydrates are broken down into glucose: Foods with a high glycemic index are associated with a faster rise and subsequent drop in blood sugar than those with a low glycemic index. In the present study, investigators analyzed diet questionnaires completed by 4,757 non-diabetic men and women participating in the nationwide Age-Related Eye Disease Study (AREDS), an eight-year study that included participants ages 55 to 80 with varying stages of AMD. They examined the participants" carbohydrate intake over one year and used the data to calculate the participants" dietary glycemic index. Results showed that those who consumed the most refined carbohydrates were 17 percent more likely to develop blinding AMD than the group that consumed the least. Based on their data, the investigators believe that limiting dietary refined carbohydrates in at-risk elderly people could reduce the number of advanced AMD cases by 8 percent in five years. The authors note that their findings warrant randomized controlled clinical trials.
    SOURCE: Chiu CJ, Milton RC, Klein R, et al. Dietary carbohydrate and the progression of age-related macular degeneration: A prospective study from the Age-Related Eye Disease Study. Am J Clin Nutr 2007;86(4):1210-8.
  • VISUAL DISPLAYS PROJECT HELPS PATIENTS WITH AMD AND OTHER VISION LOSS. An interdisciplinary team of biomedical researchers from the USC Viterbi School, the College and the Keck School of Medicine of USC has received a $6 million Bioengineering Research Partnership grant from the National Institutes of Health (NIH) to begin designing visual aids for millions of older adults who suffer from significant vision loss. The USC team will join researchers from Harvard Medical School and the University of Houston to address low-vision problems caused by neural pathologies such as age-related macular degeneration (AMD) and other diseases affecting the retina. The NIH project will concentrate on designing visual displays that help patients who have lost central vision and must rely on peripheral vision. The aim is to use techniques of computer vision and computational neuroscience to build visual displays that enhance certain parts of an image; this will allow patients with AMD to better "digest" the visual information. The focus is on the nervous system and the way in which the brain processes information rather than the optics of the eye. As part of the project, engineering faculty at USC"s Center for Vision Science and Technology will first enhance contrast in scenes and suppress background "noise"; then they will design displays that brighten the contours of objects--a sort of "cartoon" of outlines that would be more recognizable to AMD patients. Patients will be trained in techniques of perceptual learning to make the best use of the devices; statistical learning tools built into the devices will adapt automatically to the needs of the patient.
  • ENROLLMENT COMPLETE FOR PHASE III TRIAL OF MEDIDUR. Alimera Sciences and pSivida Ltd. have announced the completion of enrollment for the Fluocinolone Acetonide in Diabetic Macular Edema (FAME) study of Medidur FA for the treatment of diabetic macular edema (DME). FAME is a double masked, randomized, multicenter study that will follow more than 900 patients in the United States, Canada, Europe and India for 36 months, with safety and efficacy assessed at two years. The two companies are jointly developing Medidur FA under a collaborative research and development agreement. Medidur is a tiny, injectable insert under investigation as a means to deliver the corticosteroid fluocinolone acetonide to the retina for up to three years as a treatment for DME. Using a proprietary 25-gauge injector system, an eyecare professional injects the Medidur insert into the vitreous through a minimally invasive procedure in an outpatient setting. For more information, go to www.psivida.com.


Table of Contents

 

 

 


Check Yearly. See Clearly. Open Your Eyes To the Opportunities.
The Check Yearly. See Clearly.(SM) marketing campaign is opening consumers' eyes to the benefits of regular eye exams. Call the Vision Council of America at 800-424-8422 today or visit checkyearly.com for your free promotional materials.

 




Subscriptions: Review of Ophthalmology Online is provided free of charge as a service of Jobson Publishing, LLC. If you enjoy reading Review of Ophthalmology Online, please tell a friend or colleague about it. Forward this newsletter or send this address: [email protected]. To change your subscription, reply to this message and give us your old address and your new address; type "Change of Address" in the subject line. If you do not want to receive Review of Ophthalmology Online, reply to this message and type "Unsubscribe: Review of Ophthalmology Online" in the subject line.

Advertising: For information on advertising in this e-mail newsletter or other creative advertising opportunities with Review of Ophthalmology, please contact publisher Rick Bay, or sales managers James Henne, Michele Barrett or Kimberly McCarthy.

News: To submit news, send an e-mail, or FAX your news to 610.492.1049