Purpose-To use optical coherence tomography (OCT) to identify the specific retinal layers and macular regions damaged in glaucoma. Design-Observational cross-sectional study.Participants-One hundred forty-nine participants in the Advanced Imaging for Glaucoma Study, divided into 3 groups: normal (N) perimetric glaucoma (PG), and glaucoma suspect and preperimetric glaucoma (GSPPG) with 44, 73, and 29 persons, respectively. Methods-TheZeiss Stratus OCT system (Carl Zeiss Meditec, Inc., Dublin, CA) was used to map the macula over a 6-mm diameter and to scan the circumpapillary nerve fiber layer (cpNFL). The macular OCT images were exported for automatic segmentation using software developed by the authors. The thickness of the macular nerve fiber layer (mNFL), ganglion cell layer (mGCL), inner plexiform layer (mIPL), inner nuclear layer (mINL), outer retinal layer (mORL), and total retinal thickness were measured. Thickness measurements of GSPPG and PG eyes were compared with those of N eyes. The ability to differentiate between GSPPG and PG eyes against N eyes was assessed by fractional loss, standardized deviation, and the area under the receiver operating characteristic curve.Main Outcome Measures-Area-weighted average thicknesses of retinal sublayers in the macula.Results-The mNFL, mGCL, mIPL, and mINL were significantly (P<0.001) thinner in both the GSPPG and PG eyes than in the N eyes. In PG eyes, mNFL, mGCL, and mIPL thinning was most severe (approximately 20%), mINL thinning was intermediate (7%), and mORL thinning was minimal (3%). The repeatability (coefficient of variation and intraclass correlation) of thickness measurements was improved by combining the mNFL, mGCL, and mIPL measurements as the inner retinal layer (mIRL). The mIRL was the best macular parameter for glaucoma diagnosis and had discriminant power comparable with that of the cpNFL. The fractional loss of mIRL thickness was most severe in the inferior perifoveal region for both the PG and GSPPG groups.Conclusions-Glaucoma leads to thinning of the mNFL, mGCL, mIPL, and mINL, even before detectable visual field changes occur. A combination of the 3 innermost layers seems to provide optimal glaucoma detection. Increasing the sampling of peripheral macula with a new OCT scan pattern may improve glaucoma diagnosis further.Glaucoma is an optic neuropathy characterized by an irreversible loss of neural tissue and visual field function. Early detection of the disease or its progression is important in Advanced imaging systems such as optical coherence tomography (OCT), scanning laser polarimetry, and scanning laser tomography can measure objectively both retinal NFL thickness and optic disc contour.The macular region does not undergo clinically observable change with glaucoma. But the development of more sensitive measurement technology has sparked interest in investigating this area for glaucoma diagnosis. Zeimer 5-7 hypothesized that macular thickness was important because the retinal ganglion cell layer consists of the cell bodies of reti...
Purpose To determine the relationship between fine particulate matter (PM 2.5 ) and ocular outcomes such as visual impairment and age-related eye disease. Methods Baseline data were used from the Canadian Longitudinal Study on Aging. The Comprehensive Cohort consisted of 30,097 adults ages 45 to 85 years. Annual mean PM 2.5 levels (µg/m 3 ) for each participant's postal code were estimated from satellite data. Ozone, sulfur dioxide, and nitrogen dioxide levels were also estimated. Binocular presenting visual acuity was measured using a visual acuity chart. Intraocular pressure (IOP) was measured in millimeters of mercury using the Reichart Ocular Response Analyzer. Participants were asked about a diagnosis of glaucoma, macular degeneration, or cataract. Logistic and linear regression models were used. Results The overall mean PM 2.5 level was 6.5 µg/m 3 (SD = 1.8). In the single pollutant models, increased PM 2.5 levels (per interquartile range) were associated with visual impairment (odds ratio [OR] = 1.12; 95% confidence interval [CI], 1.02–1.24), glaucoma (OR = 1.14; 95% CI, 1.01–1.29), and visually impairing age-related macular degeneration (OR = 1.52; 95% CI, 1.10–2.09) after adjustment for sociodemographics and disease. PM 2.5 had a borderline adjusted association with cataract (OR = 1.06; 95% CI, 0.99–1.14). In the multi-pollutant models, increased PM 2.5 was associated with glaucoma and IOP only after adjustment for sociodemographics and disease (OR = 1.24; 95% CI, 1.05–1.46 and β = 0.24; 95% CI, 0.12–0.37). Conclusions Increased PM 2.5 is associated with glaucoma and IOP. These associations should be confirmed using longitudinal data and potential mechanisms should be explored. If confirmed, this work may have relevance for revision of World Health Organization thresholds to protect human health.
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