Volume 8, Number 25
Monday, June 23, 2008



In this issue: (click heading to view article)
Ischemic Optic Neuropathy Decompression Trial: Evaluation of Change in Pattern Defect and Severity Over Time
Manual Top Hat Wound Configuration for PK
Associations with IOP in Latinos: The Los Angeles Latino Eye Study
Describing Morphological Variations in Eyes with Atrophic AMD Using High-Resolution SD-OCT
Briefly










Ischemic Optic Neuropathy Decompression Trial: Evaluation of Change in Pattern Defect and Severity Over Time

Researchers at Johns Hopkins University Bloomberg School of Public Health evaluated the change from baseline to 12 months follow-up in study and nonstudy (fellow) eye visual fields from the Ischemic Optic Neuropathy Decompression Trial (IONDT), a randomized, controlled trial and observational study.

The IONDT enrolled patients 50 years and older with acute nonarteritic ischemic optic neuropathy (NAION). A total of 258 randomized patients had visual acuity less than 20/64; 160 nonrandomized patients had visual acuity better than 20/64 or refused randomization. Interventions were optic nerve decompression surgery (127 patients) or careful follow up (131 patients). Researchers measured visual fields at baseline and at six and 12 months follow up. Using a computerized system, they classified visual field defects by pattern, location and severity and examined changes over time by treatment group, age, baseline comorbidities and change in visual acuity. In fellow (nonstudy) eyes, they assessed change by whether NAION was present at baseline and assessed incidence of NAION by whether a visual field defect was present at baseline.

The study included 245 study eye visual field pairs (179 and 66, randomized and nonrandomized, respectively) for change from baseline to 12 months. Significant changes in defect distribution occurred within the central field for randomized eyes. Superior and inferior altitudinal defects were less severe at follow-up in both randomized and nonrandomized eyes. An association between change in central field severity and change in visual acuity from baseline was evident, but there was no association between visual field change and treatment group, age or baseline comorbidities. Superior and inferior visual field defects present at baseline in nonstudy eyes improved at follow up. Fellow (nonstudy) eyes with normal fields did not have an increased risk of developing NAION compared with eyes with one or greater defects.


SOURCE: Scherer RW, Feldon SE, Levin L, et al.; Ischemic Optic Neuropathy Decompression Trial Research Group. Visual fields at follow-up in the Ischemic Optic Neuropathy Decompression Trial: Evaluation of change in pattern defect and severity over time. Ophthalmol 2008; May 15. [Epub ahead of print].
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http://www.raveonhs.com/octo300/






Manual Top Hat Wound Configuration for PK

In this study, investigators compared the outcomes of manual top hat penetrating keratoplasty (PK) versus traditional PK.

The study authors reviewed the charts of 71 consecutive patients who underwent manual top hat (36 participants) or traditional PK (35 participants) at Toronto Western Hospital, University of Toronto. Main outcome measures included best-corrected Snellen visual acuity (BCVA), topographic and refractive results, high-order ocular aberrations, endothelial cell counts and complication rate.

Results showed no difference in mean BCVA between the two groups after 12 months of follow up. The mean spherical equivalent power was mild myopia, and the mean astigmatism was less than 4.2 D cylinder in both groups. There was no difference in total high-order aberrations, except spherical aberrations: 0.88 ± 0.74 microns in the top hat versus 0.49 ± 0.41 microns in the traditional PK. Endothelial cell count was significantly higher in top hat PK group, and time to all suture removal was shorter.

SOURCE: Bahar I, Kaiserman I, Srinivasan S, et al. Manual top hat wound configuration for penetrating keratoplasty. Cornea 2008;27(5):521-6.
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http://www.jobsoneducation.com/orderpub/redbook.asp






Associations with IOP in Latinos: The Los Angeles Latino Eye Study

This population-based, cross-sectional study by the Doheny Eye Institute and the Department of Ophthalmology, Keck School of Medicine, University of Southern California, evaluated the association of biologic factors with IOP in a Latino population.

A total of 5,958 Latinos aged 40 years and older from the Los Angeles Latino Eye Study who did not have a history of ocular hypotensive treatment underwent an interviewer-administered questionnaire and a complete ocular and clinical examination. IOP was obtained by applanation tonometry and was based on the mean of three measurements. Investigators used multivariable regression models to evaluate the independent association of biological factors with IOP.

Higher systolic blood pressure, higher central corneal thickness and diabetes were the major factors associated with elevated IOP. Other positively correlated variables included age, female gender, higher diastolic blood pressure, larger body mass index, darker colored irides and nuclear sclerosis. Axial length and family history of glaucoma had no association with IOP.

The authors suggest that identifying and recognizing the systemic and ocular characteristics associated with elevated IOP in Latinos will help define subgroups of the population that may be most at risk of having elevated IOP.

SOURCE: Memarzadeh F, Ying-Lai M, Azen SP, Varma R; The Los Angeles Latino Eye Study Group. Associations with intraocular pressure in Latinos: The Los Angeles Latino Eye Study. Am J Ophthalmol 2008; May 15 [Epub ahead of print].
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Describing Morphological Variations in Eyes with Atrophic AMD Using High-Resolution SD-OCT

Researchers at Germany"s University of Bonn conducted this study in an effort to describe morphological variations in outer retinal layers in eyes with atrophic AMD, using high-resolution, spectral-domain optical coherence tomography (SD-OCT).

Investigators obtained SD-OCT scans using a combined confocal scanning laser ophthalmoscope (cSLO) and SD-OCT for simultaneous tomographic and topographic in vivo imaging. They examined 81 eyes of 56 patients (mean age 77.8 ± 7.4) with geographic atrophy (GA), analyzing and classifying morphological alterations in the perilesional zone, at the junction between GA and non-atrophic retina and in the atrophic area itself.

In the perilesional zone, distinct morphological alterations included elevations of the outer retinal layers, thickening and spikes of the outer hyperreflective band as well as clumps at different neurosensory retinal levels. At the junction, highly variable transitions of the outer retinal layers were present, with different degrees of loss of the normal hyperreflective bands. Within the actual GA, hyperreflective clumps at different retinal levels, segmented plaques of the outer band and elevations with variable reflectivity were visualized.

SD-OCT imaging in eyes with GA revealed a wide spectrum of morphological alterations, both in the surrounding retinal tissue and in the atrophic area. The authors believe that these alterations may reflect different disease stages or, alternatively, heterogeneity on a cellular and molecular level. Longitudinal studies using in vivo SD-OCT imaging may allow researchers to evaluate the relevance of these phenotypic changes as potential predictive markers for the progression of disease (enlargement rates of GA over time) and may be used for monitoring of future therapeutic interventions.

SOURCE: Fleckenstein M, Charbel Issa P, Helb HM, et al. High resolution spectral domain-OCT imaging in geographic atrophy associated with age-related macular degeneration. Invest Ophthalmol Vis Sci 2008; May 16. [Epub ahead of print].
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BRIEFLY
  • CLINICAL STUDY OF LASER-BASED GLAUCOMA THERAPY SUCCESSFULLY COMPLETED. IOPtima, a subsidiary of Bio-Light Life Science Investments, has successfully completed a three-month follow-up period for an initial human clinical study using the company"s OT134 device and procedure, a novel, laser-based therapy that will allow eye surgeons to operate and reduce internal eye pressure without penetrating the eye membrane. The company"s non-penetrating deep sclerotomy (NPDS) surgery is similar to a trabeculectomy, but the procedure is modified to reduce side effects. Both technologies reduce IOP by removing scleral tissue in a small flap of the eye. In conventional trabeculectomy, the surgeon penetrates through the wall of the eye; in the NPDS procedure, the surgeon penetrates to approximately 95 percent of the scleral depth, leaving a residual intact thin layer several dozen microns thick. In the study, 13 patients were treated by NPDS at a glaucoma center in Mexico City, marking the first leg in what IOPtima says will be a multi-national clinical trial at leading ophthalmology centers around the world. The company aims to obtain regulatory approval for Europe and plans to meet with the FDA to initiate procedures aimed at U.S. regulatory approval.
  • LIGHT SENSORS THAT CONTROL "BODY CLOCK" FOUND IN THE EYE. Scientists have discovered the function of a third type of light sensor in the eye, related not to vision, but to control of the body"s internal clock. The investigators believe the discovery may offer a new pathway for potential treatments of light-related mood and sleep disorders. The sensors, found in two percent of retinal cells, are dedicated to detecting the presence and intensity of light through the use of a light-sensitive molecule called melanopsin, according to the report of the study results in the journal PLoS ONE. Nocturnal mice in the study that did not have the sensor were unable to reset their internal biological clocks and thus woke up one-half hour earlier every evening, without adjusting to a 24-hour day. Project leader Satchin Panda of the Regulatory Biology Laboratory at the Salk Institute for Biological Studies in La Jolla, CA, said that searches of the recently sequenced mouse and human genomes revealed that both contained an extra light sensor gene. The researchers narrowed the sensor"s location to a small number of retinal cells and genetically engineered mice with sensor cells sensitive to a particular toxin. When the mice were exposed to the toxin, only the cells containing melanopsin died. The animals could still see normally and retained depth perception, but they became unable to discern and respond to light intensity. The results confirm those of a separate study reported earlier this year in the journal Nature.

    SOURCE: Hatori M, Le H, Vollmers C, et al. Inducible ablation of melanopsin-expressing retinal ganglion cells reveals their central role in non-image forming visual responses. PLoS ONE 2008;3(6): e2451 .

  • FIVE-YEAR SAFETY STUDY EXAMINES EFFECT OF INSULIN ANALOG ON DR PROGRESSION. A five-year safety study designed to assess the risk of exacerbation of diabetic retinopathy (DR) in patients with Type II diabetes who are treated with the basal insulin analog Lantus (insulin glargine [rDNA origin] injection) showed similar progression of retinopathy for Lantus compared with NPH, a human insulin that has been available for several decades and has a well-known safety profile. The study used 7-field fundus photography and the Early Treatment Diabetic Retinopathy Study (ETDRS) scale to evaluate progression of retinopathy. Randomized Type II diabetes patients received Lantus once daily or NPH twice daily, titrated over the first three years to target fasting plasma glucose (FPG) levels of 6.7 mM and 5.5 mM, with HbA1c 7 percent or less over the last two years of the study. Results showed that DR at baseline tended to be more prevalent and the baseline ETDRS score greater in the Lantus group; however, non-inferiority for three-step progression of retinopathy for Lantus versus NPH was established in the per-protocol population and confirmed in the intent-to-treat population. Both groups achieved mean FPG 7.7 mM at endpoint, despite a trend toward less basal insulin use in the Lantus group.


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