Correlation of iris collagen and in-vivo anterior segment structures in patients in different stages of chronic primary angle-closure in both eyes.

Purpose: To compare the density of iris collagen and anterior segment parameters in eyes with chronic primary angle closure glaucoma (CPACG) and their fellow eyes with confirmed or suspected primary angle closure (PAC/PACS). Methods: Nineteen patients with CPACG in one eye and PAC/PACS in the fellow eye requiring trabeculectomy in the CPACG eye and iridectomy in the fellow eye were recruited. Anterior segment optical coherence tomography (AS-OCT) measurements were conducted under light and dark conditions. Iris specimens, obtained by iridectomy/trabeculectomy, were analyzed by sirius red polarization for quantifying type I/III collagen density. AS-OCT parameters and type I/III collagen densities were compared between the two eyes. Results: The iris curvatures were flatter in CPACG eyes in light and dark conditions (P < 0.05). The iris areas in light condition and iris thicknesses in dark condition were smaller in CPACG eyes (P < 0.05). The density of collagen type I in CPACG eyes was lower (P = 0.048). The light-to-dark changes in CPACG eyes and PAC/PACS eyes, respectively, were -0.679 ± 0.701 and -1.627 ± 0.802 mm for pupil diameters, and 0.069 ± 0.113 and 0.258 ± 0.157 mm2 for iris areas, which differed significantly (P < 0.001). With the decrease of type I collagen, anterior chamber width increased and iris areas decreased in dark condition. Conclusion: Dynamic changes in pupil diameter and iris areas differed significantly between CPACG eyes and their fellow PAC/PACS eyes. Decreased type I collagen density in iris tissue was associated with decreased iris area and increased anterior chamber width, which may contribute to disease progression.

Dynamic changes of anterior segment in patients with different stages of primary angle-closure in both eyes and normal subjects.

PURPOSE: To compare changes in anterior segment parameters under light and dark (light-to-dark) conditions among eyes with chronic primary angle-closure glaucoma (CPACG), fellow eyes with confirmed or suspect primary angle-closure (PAC or PACS), and age-matched healthy eyes. METHODS: Consecutive patients with CPACG in one eye and PAC/PACS in the fellow eye, as well as age-matched healthy subjects were recruited. Anterior segment optical coherence tomography measurements were conducted under light and dark conditions, and anterior chamber, lens, and iris parameters compared. Demographic and biometric factors associated with light-to-dark change in iris area were analyzed by linear regression. RESULTS: Fifty-seven patients (mean age 59.6±8.9 years) and 30 normal subjects matched for age (60.6±9.3 years) and sex ratio were recruited. In regards to differences under light-to-dark conditions, angle opening distance at 500 µm (AOD500µm) and iris area during light-to-dark transition were smaller in CPACG eyes than fellow PACS/PAC eyes and normal eyes (P<0.017). Pupil diameter change was largest in normal eyes, and larger in PACS/PAC eyes than CPACG eyes (P<0.017). There was an average reduction of 0.145 mm2 in iris area for each millimeter of pupil diameter increase in CPACG eyes, 0.161 mm2 in fellow PAC/PACS eyes, and 0.165 mm2 in normal eyes. Larger iris curvature in the dark and diagnosis of PACG were significantly associated with less light-to-dark iris area changes. CONCLUSIONS: Dynamic changes in iris parameters with light-to-dark transition differed significantly among CPACG eyes, fellow PAC/PACS eyes, and normal eyes. Greater iris curvature under dark conditions was correlated with reduced light-to-dark change in iris area and pupil diameter, which may contribute to disease progression.

Quantitative Measurements of the Ciliary Body in Eyes With Acute Primary-Angle Closure.

PURPOSE: To compare the structural differences of the ciliary body in patients with acute primary-angle closure (APAC) and normal subjects. METHODS: Forty-four patients with APAC in one eye and 25 eyes from 25 age-matched normal subjects were consecutively recruited. A-scan ultrasound and ultrasound biomicroscopy (UBM) measurements were performed. Ciliary body parameters including maximum ciliary body thickness (CBTmax), ciliary body thickness at point of the scleral spur (CBT0) and 1000 µm from the scleral spur (CBT1000), anterior placement of ciliary body (APCB), and trabecular-ciliary process angle (TCA), as well as biometric measurements, were measured. RESULTS: Average CBTmax was 0.894 ± 0.114, 0.967 ± 0.110, and 1.053 ± 0.103 mm in eyes with APAC, their fellow eyes, and normal eyes, respectively. Average CBT1000 was 0.616 ± 0.111, 0.631 ± 0.088, and 0.842 ± 0.118 mm, respectively. Average TCA was 48.10 ± 13.26°, 50.60 ± 9.08°, and 87.11 ± 20.71°, respectively. CBTmax and CBT0 were thinner in eyes with APAC compared with their fellow eyes (P = 0.002, P < 0.001). In addition, CBTmax, CBT1000, and TCA were smaller whereas APCB was larger in the fellow eyes of APAC patients compared with normal eyes (P = 0.002, P < 0.001, P < 0.001, P < 0.001). The anterior chamber depth (ACD) was smaller whereas lens thickness (LT) was larger in eyes with APAC compared with their fellow eyes (P < 0.001, P = 0.036). Smaller ACD and axial length and larger LT and lens vault were found in the fellow eyes of APAC patients compared with normal eyes (P < 0.001, P < 0.001, P = 0.015, P = 0.001). CONCLUSIONS: Ciliary bodies were thinner and more anteriorly rotated in eyes with APAC as well as in their fellow eyes. Further studies are needed to elucidate the relationship between ciliary body parameters and mechanism of APAC.