Ultrasound biomicroscopy and iris pigment dispersion: a case-control study

Mora, Paolo; Sangermani, C.; Ghirardini, Stella; Carta, Arturo; Ungaro, Nicola; Gandolfi, S.

doi:10.1136/bjo.2009.162065

Cited by 23 publications

(11 citation statements)

References 18 publications

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“…2 Providing cross-sectional imaging technology for detailed evaluation of the eye in vivo and in real-time is technically challenging but could help us better understand the mechanisms of accommodation and presbyopia and in the long term set the foundations for new procedures and implants aimed to restore dynamic accommodation. Magnetic resonance imaging (MRI), 3–5 ultrasound biomicroscopy (UBM), 6–8 and Scheimpflug camera (SC) based optical systems 5, 9–11 have been used to study the anatomical changes occurring in the eye during accommodation. In the past few years, optical coherence tomography (OCT) has been increasingly used to study accommodation in vivo and in real-time 12–30 since it has several advantages over the other ophthalmic imaging technologies.…”

Section: Introductionmentioning

confidence: 99%

Dynamic imaging of accommodation by swept-source anterior segment optical coherence tomography

Néri¹,

Ruggeri²,

Protti³

et al. 2015

Journal of Cataract and Refractive Surgery

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Purpose To study the accommodation process in normal eyes using a commercially available clinical system based on swept-source anterior-segment optical coherence tomography (SS-AS-OCT). Setting Ophthalmology, University of Parma, Parma, Italy. Design Experimental study. Methods The right eye of 14 healthy volunteers (18–46 years) was analyzed with SS-AS-OCT. The optical vergence of the coaxial fixation target integrated in the OCT device was adjusted during imaging to obtain monocular accommodation stimuli with different amplitudes (ASA: 0, 3, 6 and 9 Diopters). Overlapping of real and conjugate OCT images enabled imaging of all the anterior segment optical surfaces in a single frame. Intraocular distances including central corneal thickness (CCT), anterior chamber depth (ACD) and lens thickness (LT) were extracted from the OCT scans acquired at different static ASA. Dynamic analysis of the crystalline lens was also performed during accommodation and disaccommodation by sequentially acquiring OCT images of the anterior segment at a rate of 8 frames per second. LT was extracted from the temporal sequence of OCT images and plotted as a function of time. Results With accommodation ACD decreased significantly (p<0.05), LT increased (p<0.001) and lens central point moved slightly forward (p<0.01). CCT and ACW measurements did not change significantly with accommodation, which in turn confirmed that centering of the eye in the OCT images was maintained through ASA. LT at 0D was positively correlated with age (range: 3.131–4.088mm, r=0.772, p<0.01). Conclusions High-resolution real-time imaging and biometry of the accommodating anterior segment can be effectively performed with a commercial SS-AS-OCT clinical device.

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Section: Introductionmentioning

confidence: 99%

Dynamic imaging of accommodation by swept-source anterior segment optical coherence tomography

Néri¹,

Ruggeri²,

Protti³

et al. 2015

Journal of Cataract and Refractive Surgery

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“…Apparent contact length, commonly used in UBM studies (Kanadani et al, 2006; Liebmann et al, 1995; Merula et al, 2008; Mora et al, 2010; Pavlin et al, 1992; Woo et al, 1999; Yoon et al, 2004), is defined as the distance over which there is no resolvable space between the iris and lens in the UBM image. In the computational model, we estimated the apparent contact as the distance over which the iris was at most 50μm from the lens.…”

Section: Methodsmentioning

confidence: 99%

Increased iris–lens contact following spontaneous blinking: Mathematical modeling

Amini

Jouzdani

Barocas

2012

Journal of Biomechanics

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The purpose of this work was to study in silico how iris root rotation due to spontaneous blinking alters the iris contour. An axisymmetric finite-element model of the anterior segment was developed that included changes in the iris contour and the aqueous humor flow. The model geometry was based on average values of ocular dimensions. Blinking was modeled by rotating the iris root posteriorly and returning it back to the anterior. Simulations with maximum rotations of 2°, 4°, 6°, and 8° were performed. The iris-lens contact distance and the pressure difference between the posterior and anterior chambers were calculated. When the peak iris root rotation was 2°, the maximum iris-lens contact increased gradually from 0.28 to 0.34 mm within eight blinks. When the iris root was rotated 6° and 8°, the pressure difference between the posterior and anterior chambers dropped from a positive value (1.23 Pa) to negative values (−0.86 and −1.93 Pa) indicating the presence of reverse pupillary block. Apparent iris-lens contact increased with steady blinking, and the increase became more pronounced as posterior rotation increased. We conclude that repeated iris root rotation caused by blinking could maintain the iris in a posterior position under normal circumstances, which would then lead to the clinically-observed anterior drift of the iris when blinking is prevented.

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“…This includes anterior rotation of the ciliary body in plateau iris, iridociliary masses causing secondary angle closure or choroidal effusions. [2830] Additionally, UBM may also play a role in the evaluation of certain types of secondary glaucoma, such as pigment dispersion[31] (posteriorly bowed, causing iris pigment shaffing) and assessing for a tilted or subluxed lens in the exfoliation syndrome. [32]…”

Section: Ultrasound Biomicroscopymentioning

confidence: 99%

Angle imaging: Advances and challenges

Quek

Nongpiur

Perera

et al. 2011

Indian J Ophthalmol

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Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard.

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Ultrasound biomicroscopy and iris pigment dispersion: a case-control study

Abstract: All UBM parameters examined were statistically different between the two groups. ROC analysis showed ICA and IC in near vision to be the most discriminatory parameters. This evidence confirms the importance of iris movements in inducing the particular features of PDS/PG.

Cited by 23 publications

References 18 publications

Dynamic imaging of accommodation by swept-source anterior segment optical coherence tomography

Dynamic imaging of accommodation by swept-source anterior segment optical coherence tomography

Increased iris–lens contact following spontaneous blinking: Mathematical modeling

Angle imaging: Advances and challenges

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