Faculty Bibliography

PURPOSE/OBJECTIVE:To assess the impact on visual function of community glaucoma screening in an African American population using spectral-domain optical coherence tomography (SD-OCT). METHODS:Using a Monte Carlo microsimulation model with a 10-year time horizon, we analyzed the efficacy of SD-OCT screening on visual field outcomes in a population of African Americans who are not otherwise seeking office-based care. Outcomes included classification of visual field severity, quality-adjusted life years, and direct health care costs. RESULTS:Assuming a 60% follow-up rate, screening decreased the prevalence of undiagnosed glaucoma from 75% to 38%, and decreased the prevalence of severe visual field loss in patients with glaucoma from 29.1% to 23.9%. Conversely, screening increased the prevalence of mild visual field loss in patients with glaucoma from 9.2% to 18.7%. From initial screening through confirmatory eye examination, the screening program ("screen only") cost $98 per screened individual, and $2561 per new diagnosis of glaucoma. When considering the costs of initial screening though the resultant treatment, the screening program ("screen and treat") had an average annual cost of $79 and $2138, respectively, over a 10-year time period. The cost of one quality-adjusted life year (QALY) gained by screening, including management and treatment, in comparison with opportunistic case finding, ranged from $46,416 to $67,813. CONCLUSIONS:Our findings suggest that community SD-OCT screening in an African American population will minimize glaucoma-related visual morbidity. Ideally, strategies to maximize treatment efficacy through improved medication adherence and improved compliance with follow-up should be identified and implemented before instituting a screening program.

PURPOSE/OBJECTIVE:To compare the intermediate-term intraocular pressure (IOP) control and complication profile of the Ahmed Glaucoma Valve (AGV) implanted posteriorly through the pars plana in eyes undergoing concurrent pars plana vitrectomy (PPV) with device implantation in the anterior chamber (AC) in nonvitrectomized eyes. METHODS:: We retrospectively reviewed the medical records of 31 case eyes (30 patients) with refractory glaucoma that underwent posterior implantation of AGV after complete PPV and compared them to 31 control eyes (31 patients) with refractory glaucoma that underwent implantation of AGV in the AC. Case-control patients were matched one-to-one on the basis of principal glaucoma diagnosis. All surgeries were performed at 1 institution using a silicone-plate device. Success was defined as intraocular pressure (IOP)≥ 5 mm Hg and ≤ 21 mm Hg with or without glaucoma medications at final follow-up, no additional glaucoma surgery, no removal of the implant, and no loss of light perception. RESULTS:The average follow-up was 20.9 months (range, 6 to 54 mo) for the posterior group and 20.5 months (range, 4 to 48 mo) for the anterior group. The reduction in IOP was similar in both groups at all postoperative time points. The number of postoperative glaucoma medications in both groups was not statistically different at final follow-up. Success rates at final follow-up were identical, 83.9% in both groups, and Kaplan-Meier survival curve analysis showed no significant difference between the 2 groups (P=0.96). Postoperative complications were similar between the 2 groups, except there were more instances of early postoperative flat AC in the anterior group than the posterior group (P=0.01). CONCLUSIONS:The AGV can similarly control IOP in the majority of cases, whether the tube is placed in the posterior segment after PPV or in the AC of nonvitrectomized eyes.

PURPOSE/OBJECTIVE:To evaluate corneal graft survival and intraocular pressure (IOP) control after penetrating keratoplasty (PK) and pars plana Ahmed Glaucoma Valve (AGV) implantation among patients with coexisting glaucoma and corneal disease. METHODS:Retrospective chart review at an institution of 25 eyes (24 patients) that received PK and pars plana AGV. RESULTS:The mean postoperative follow-up was 23 months (range, 2-106 months). Survival of the grafts was 89% (16 of 18 eyes) at 1 year and 63% (5 of 8) at 2 years. IOP control was 78% (15 of 19) at 1 year and 44% (4 of 9) at 2 years. By Kaplan-Meier analysis, the 50% probability of sustained graft clarity occurred at 28 months and that of sustained IOP control at 24 months. By last follow-up, best-corrected visual acuity had improved by at least 1 line in 52% (13 of 25) of eyes compared with preoperative values. Preoperative factors, including peripheral anterior synechiae, were not found to be associated with graft survival, IOP control, or visual acuity at 1 year. CONCLUSION/CONCLUSIONS:Pars plana AGV can successfully control IOP in PK patients in the short and intermediate terms, but graft clarity and IOP control diminish over time. Graft decompensation, when it did occur, likely reflects the associated ocular morbidity and clinical complexity of this circumscribed cohort of eyes.

PURPOSE: To introduce a rapid and objective electrophysiological technique that can assess visual function in the magnocellular pathway, which is thought to be affected in early-stage glaucoma. METHODS: Low-contrast bright or dark isolated-checks were luminance-modulated against a static background at 10 Hz in order to drive preferentially the magnocellular ON or OFF pathway. Visual evoked potentials were recorded during 1-s epochs of stimulation and responses at the stimulus frequency were measured. Artifact rejection features ensured that eight valid runs were obtained per eye. Signal-to-noise ratios (SNR) were derived based on a multivariate statistic. In order to demonstrate its functionality, a small group of patients with glaucoma (N = 18, Snellen acuity of 20/30 or better) and control observers (N = 16) were tested. A participant failed the test if either eye yielded an SNR < or = 1. Receiver-operating-characteristic curve analysis was used to estimate the accuracy of group classification. RESULTS: The instrument was found to elicit reliable responses from control observers. For the 15% bright condition, all control observers yielded significant isolated-check VEPs (icVEPs), whereas the majority of patients failed to do so, indicating significant losses in central visual function. This condition produced the highest classification accuracy (94%), followed by the 10% dark condition (91%). CONCLUSIONS: Both ON and OFF divisions of the magnocellular pathway can be assessed rapidly through the application of the icVEP technique. This measure of central visual function may be of value in the detection of glaucomatous deficits and may complement tests of peripheral function

PURPOSE/OBJECTIVE:To report a case of cilioretinal artery occlusion with normal fluorescein angiography findings that was evaluated by electroretinography (ERG) and microperimetry. METHODS:A 64-year-old-man presented with an oval paracentral scotoma in the temporal field of the left eye that became more evident after cataract surgery. Fundus photography, fluorescein angiography, ERG, multifocal ERG, and microperimetry were performed. RESULTS:Multifocal ERG showed decreased signal amplitudes in areas corresponding to areas with a visual defect as detected by microperimetry. Pattern ERG also showed a defect in the P50 component. Findings of fundus photography, fluorescein angiography, and full-field ERG were within normal limits. CONCLUSION/CONCLUSIONS:This case demonstrates the possibility of using ERG and microperimetry as noninvasive tools in the diagnosis of cilioretinal artery occlusion.

PURPOSE/OBJECTIVE:To measure the peripapillary retinal nerve fiber layer (RNFL) thickness in normal children. DESIGN/METHODS:Observational cross-sectional study. PARTICIPANTS/METHODS:Ninety-two eyes of 92 normal children ages 4 to 17 years presenting to the Ophthalmology Clinic at the Harkness Eye Institute, Department of Ophthalmology, Columbia University. METHODS:Retinal nerve fiber layer thickness was measured with optical coherence tomography (OCT). Patient cooperation and signal strength of the OCT scans were assessed. Optic disc photographs were evaluated by a glaucoma specialist in a masked fashion. Eyes with abnormal optic discs were excluded. One eye of each subject was randomly selected for statistical analysis. The effect of several factors on RNFL thickness was investigated statistically. MAIN OUTCOME MEASURES/METHODS:Retinal nerve fiber layer thickness. RESULTS:Ninety-one percent of the study subjects were Hispanic; 8%, African American; and 1%, Caucasian. Optical coherence tomography measurements were obtained in 117 of 121 (96.7%) subjects, and disc photographs were available for 92 of them. Mean age (+/-standard deviation [SD]) was 9.7+/-2.7 years. Mean global RNFL thickness (+/-SD) was 107.0+/-11.1 microm (range, 78.1-134.6). The RNFL was thickest inferiorly (136.9+/-16.9 microm) and superiorly (135.4+/-19.3 microm), thinner nasally (83.0+/-18.0 microm), and thinnest temporally (72.5+/-13.4 microm). In univariate regression analysis, age (P = 0.013) and refraction (P<0.001) had a significant effect on RNFL thickness; age had a significant effect on refraction (P<0.001). When controlling for refraction, age no longer had a significant effect. CONCLUSIONS:Optical coherence tomography can be used to measure RNFL thickness in children. Refraction had an effect on RNFL thickness. In normal children, variation in RNFL thickness is large. The normative data provided by this study may assist in identifying changes in RNFL thickness in children.