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Rizwana Siddiqi, David B. Henson, Velota Sung, Peter A. Good; Anterior Segment Morphology Of Young Patients With Primary Angle Closure. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3266.
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Patients with Primary Angle Closure (Glaucoma) or PAC(G) are frequently associated with: reduced axial length, increased lens thickness, increased iris thickness, and crowded anterior chambers. This study investigates the anterior segment morphology of PAC(G) in younger patients using ultrasound biomicroscopy (UBM).
Consecutive patients with a diagnosis of irido-trabecular contact (ITC) or PAC(G) were recruited from glaucoma clinics at the Birmingham & Midland Eye Centre. Twenty young patients (group 1) with PAC(G) and twenty older patients (group 2) underwent UBM using a linear 50 MHz probe. Measurements of: anterior chamber depth (ACD), anterior chamber width (ACW), lens thickness, axial length were made, together with angle-scleral spur distance were made and compared to 20 patients with angle closure aged > 40 years. Statistical analysis was by pooled two sample t test.
Data was collected in 20 eyes of 20 young patients (age range 30 -39 years with PAC(G) and twenty eyes of older patients (40-59 years) with PAC(G). Table 1 shows the mean values for each biometric parameter in two different age groups. AC width (p< 0.001), AC depth (p< 0.001), and axial length were all significantly greater in the younger group (0.03<p0.02).Angle to sclera spur distance (p< 0.001), lens vault (p< 0.001) and lens thickness (p< 0.001) were significantly shorter in the younger group compared to the older group (p<0.001). Anteriorly rotated ciliary bodies were noted in 8 patients in the younger group, and 4 patients in the older group. Thin irides were noted in 9 patients in the younger group alone.
There appears to be significant differences in biometric measurements of ACD, AC width, lens vault and axial length between the two groups. The lens plays a greater part in the pathogenesis of PAC(G) in older patients - as indicated by the difference in lens vault. Younger individuals with PAC(G) are characterised by deeper and wider anterior chamber, longer axial lengths, more anterior iris insertion, and thinner irides when compared to an older group of PAC(G) patients. We suggest anterior chamber dysgenesis and plateau iris are the most common causes of PAC(G) in younger patients.
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