The choroid in glaucoma
Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA. Current opinion in ophthalmology
(Impact Factor: 2.5).
01/2013; 24(2). DOI: 10.1097/ICU.0b013e32835d9245
Purpose of review:
Prior studies have not conclusively established a relationship between the choroid and glaucoma. The development of an enhanced imaging technique for spectral domain optical coherence tomography (SD-OCT) has allowed for measurements of choroidal thickness that are more accurate than previously possible. Therefore, the SD-OCT may be capable of documenting the changes in the choroid as they relate to glaucoma.
When applied to the SD-OCT, the technique of enhanced depth imaging allows for reproducible measurements of choroidal thickness. Nine reports have been published about choroidal thickness within the macula, as measured by OCT, in eyes with glaucoma. In six publications, there was no significant difference between the macular choroidal thicknesses of patients with glaucoma compared with those without glaucoma. Additional five studies have reported on peripapillary choroidal thickness in glaucoma patients. Although three of the studies determined that the peripapillary choroid is thinner in glaucoma patients, two others failed to establish this relationship.
The SD-OCT is capable of reproducibly measuring choroidal thickness in the peripapillary and macular areas. In those with glaucoma, choroidal thickness does not change within the macula. In a few subsets of glaucoma, the peripapillary choroid is thinner when compared with normals.
Available from: Hee Chan Kim
- "The fact that iris volume dynamically increases during pupil dilation supports the theory that some patients show physiological predisposition to angle closure [16,17]. Choroidal expansion has been observed in both untreated and treated acute and chronic primary-angle closure . Of the multiple factors associated with PAC(G) pathogenesis, the LV is determined by lens thickness and position, but the rLV is influenced also by the AL and ACD. "
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The purpose of this study was to investigate the association of a novel biometric parameter, relative lens vault (LV), with primary angle-closure (PAC) and primary angle-closure glaucoma (PACG).
We evaluated 101 subjects with PAC (G) and 101 normal subjects that were age- and gender-matched. Based on anterior-segment optical coherence tomography scans, and using customized software, the anterior vault (AV) and LV were measured. They were defined as the maximum distances between the horizontal line connecting the two scleral spurs and the posterior corneal surface and anterior lens surface, respectively. The relative LV was calculated by dividing the LV by the AV.
Significant differences between PAC (G) eyes and normal eyes were found in the LV (1.06 ± 0.41 vs. 0.36 ± 0.37 mm, P < 0.001), relative LV (0.34 ± 0.23 vs. 0.11 ± 0.25, P < 0.001), and axial length (22.96 ± 0.94 vs. 24.02 ± 1.33 mm, P < 0.001). However, the two groups’ values of the AV relative to those of axial length were quite similar (both 0.14 ± 0.03, P = 0.91). The relative LV values distinguished between PAC (G) eyes and normal eyes better than the LV values (area under the receiver operator characteristic curve: 0.97 vs. 0.92, P = 0.032).
Our results suggest that relative dimensions of the eyeball’s anterior portion in PAC (G) eyes might be within the normal range. And the value of LV relative to that of the AV (i.e., the relative LV) is more closely related to PAC (G) than is the absolute value of LV.
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ABSTRACT: Nonarteritic anterior ischemic optic neuropathy (NA-AION) is the most common nonglaucomatous optic neuropathy in adults over 50 years of age. It is usually related to cardiovascular risk factors. The primary objective of this study was to evaluate choroidal thickness in patients with chronic NA-AION, and the secondary objective was to evaluate macular thickness in these patients. This cross-sectional study compared two groups: group 1 included 20 eyes of 20 patients with chronic NA-AION, and group 2 included 31 eyes of 31 healthy controls. In both groups, the choroidal thickness was measured using the enhanced depth imaging program of Heidelberg Spectralis® optical coherence tomography (Heidelberg Engineering, Heidelberg, Germany). The macular thickness was also measured using the automatic software of the same device. The mean follow-up time after NA-AION in group 1 was 57.17 ± 26.92 months. The mean choroidal thickness of the posterior pole was 244.38 ± 61.03 µm in group 1 and 214.18 ± 65.97 µm in group 2 (p = 0.004). The mean macular thickness was higher in group 2. Macular thickness is reduced in eyes that had an episode of NA-AION, whereas choroidal thickness is generally higher in these eyes when compared with normal eyes. The increase in choroidal thickness may be due to a local dysfunction in vascular autoregulatory mechanisms, which may predispose to ischemic phenomena.
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