scholarly journals Probing biomechanical properties of the cornea with air-puff-based techniques – an overview

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Patryk Mlyniuk ◽  
Ewa Maczynska-Walkowiak ◽  
Jagoda Rzeszewska-Zamiara ◽  
Ireneusz Grulkowski ◽  
Bartlomiej J. Kaluzny
Keyword(s):  
Intraocular Pressure ◽  
Mechanical Load ◽  
Accurate Determination ◽  
Anterior Segment ◽  
External Environment ◽  
Standard Technique ◽  
Biomechanical Properties ◽  
Corneal Biomechanics ◽  
Optical Methods ◽  
Optical Coherence

Abstract The cornea is a part of the anterior segment of the eye that plays an essential optical role in refracting the light rays on the retina. Cornea also preserves the shape of an eyeball and constitutes a mechanical barrier, protecting the eye against the factors of the external environment. The structure of the cornea influences its biomechanical properties and ensures appropriate mechanical load transfer (that depends on the external environment and the intraocular pressure) while maintaining its shape (to a certain extent) and its transparency. The assessment of the corneal biomechanics is important in clinical ophthalmology, e.g. in the diagnosis of ectatic corneal diseases, for precise planning of the refractive surgery, and in accurate determination of the intraocular pressure. A standard technique to determine corneal biomechanics requires the application of well-defined mechanical stimulus (e.g. air puff) and performing simultaneous imaging of the response of the tissue to the stimulus. A number of methods to assess the biomechanical properties of the cornea have been developed, including ultrasound, magnetic resonance imaging, and optical methods as visualization modalities. Commercially available methods include the ocular response analyzer (ORA) and corneal visualization scheimpflug technology (Corvis ST). Currently advanced research is conducted using optical coherence tomography (OCT). The extension of OCT called optical coherence elastography (OCE) possesses high clinical potential due to the imaging speed, noncontact character, and high resolution of images.

scholarly journals The Use of Anterior-Segment Optical-Coherence Tomography for the Assessment of the Iridocorneal Angle and Its Alterations: Update and Current Evidence

2021 ◽  
Vol 10 (2) ◽  
pp. 231
Author(s):  
Giacinto Triolo ◽  
Piero Barboni ◽  
Giacomo Savini ◽  
Francesco De Gaetano ◽  
Gaspare Monaco ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Intraocular Pressure ◽  
Clinical Relevance ◽  
Anterior Segment ◽  
Angle Closure ◽  
Current Evidence ◽  
Optical Coherence ◽  
Iridocorneal Angle ◽  
Wide Range

The introduction of anterior-segment optical-coherence tomography (AS-OCT) has led to improved assessments of the anatomy of the iridocorneal-angle and diagnoses of several mechanisms of angle closure which often result in raised intraocular pressure (IOP). Continuous advancements in AS-OCT technology and software, along with an extensive research in the field, have resulted in a wide range of possible parameters that may be used to diagnose and follow up on patients with this spectrum of diseases. However, the clinical relevance of such variables needs to be explored thoroughly. The aim of the present review is to summarize the current evidence supporting the use of AS-OCT for the diagnosis and follow-up of several iridocorneal-angle and anterior-chamber alterations, focusing on the advantages and downsides of this technology.

scholarly journals Age-Related Changes in the Rhesus Macaque Eye

2021 ◽  
Author(s):  
Kira Lin ◽  
Tu Tran ◽  
Soohyun Kim ◽  
Sangwan Park ◽  
Jiajia Chen ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Intraocular Pressure ◽  
Rhesus Macaque ◽  
Axial Length ◽  
Rhesus Macaques ◽  
Anterior Segment ◽  
Optical Coherence ◽  
Lens Thickness ◽  
Age Related ◽  
Age Related Changes

Purpose: To assess age-related changes in the rhesus macaque eye and evaluate them to corresponding human age-related eye disease. Methods: Data from eye exams and imaging tests including intraocular pressure (IOP), lens thickness, axial length, and retinal optical coherence tomography (OCT) images were evaluated from 142 individuals and statistically analyzed for age-related changes. Quantitative autofluorescence (qAF) was measured as was the presence of macular lesions as related to age. Results: Ages of the 142 rhesus macaques ranged from 0.7 to 29 years (mean=16.4 years, stdev=7.5 years). Anterior segment measurements such as IOP, lens thickness, and axial length were acquired. Advanced retinal imaging in the form of optical coherence tomography and qAF were obtained. Quantitative assessments were made and variations by age groups were analyzed to compare with established age-related changes in human eyes. Quantitative analysis of data revealed age-related increase in intraocular pressure, ocular biometry (lens thickness and axial length), and presence of macular lesions. Age-related changes in thicknesses of retinal layers on OCT were observed and quantified. Age was correlated with increased qAF. Conclusions: The rhesus macaque has age-related ocular changes similar to humans. IOP increases with age while retinal ganglion cell layer thickness decreases. Macular lesions develop in some aged animals. Our findings support the concept that rhesus macaques may be useful for the study of important age-related diseases such as glaucoma, macular diseases, and cone disorders, and for development of therapies for these diseases.

scholarly journals Assessing the biomechanical properties of the porcine crystalline lens as a function of intraocular pressure with optical coherence elastography

2018 ◽  
Vol 9 (12) ◽  
pp. 6455 ◽  
Author(s):  
Chen Wu ◽  
Salavat R. Aglyamov ◽  
Zhaolong Han ◽  
Manmohan Singh ◽  
Chih-Hao Liu ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Crystalline Lens ◽  
Biomechanical Properties ◽  
Optical Coherence

Anterior chamber particles are associated with reduction of intraocular pressure after selective laser trabeculoplasty

2020 ◽  
pp. bjophthalmol-2019-315445
Author(s):  
Alexei N Kulikov ◽  
Dmitrii S Maltsev ◽  
Alina A Kazak ◽  
Maria A Burnasheva
Keyword(s):  
Optical Coherence Tomography ◽  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Open Angle Glaucoma ◽  
Anterior Segment ◽  
Optical Coherence ◽  
Selective Laser Trabeculoplasty ◽  
Cross Sectional ◽  
Laser Trabeculoplasty ◽  
The Mean

PurposeTo study the correlation between intraocular pressure (IOP) reduction and the number of hyper-reflective particles appearing in the anterior chamber following selective laser trabeculoplasty (SLT).Material and methodsIn this prospective interventional study, we included primary open-angle glaucoma patients. All participants received a standardised SLT session, which consisted of 100 pulses of 0.9 mJ over 360°. Anterior segment optical coherence tomography (4×4 mm volume scan, 101 horizontal cross-sectional scans) and applanation tonometry were performed before SLT and 15 min, 1 day, 1 week, 1 month and 3 months after. Particles were counted on cross-sectional scans using a standardised algorithm.ResultsIn this study, we included 25 patients (25 eyes), 14 males and 11 females, with a mean age of 68.9±10.5 and baseline IOP of 21.4±4.5 mm Hg. IOP at month 1 and month 3 after SLT was 18.0±4.0 and 17.4±3.3 mm Hg, respectively. The mean number of anterior chamber particles before and 15 min after SLT was 0.62±0.2 and 7.1±2.0 particles/mm2, respectively (p=0.036). There was a statistically significant correlation between the mean number of anterior chamber particles 15 min after SLT and IOP reduction at 1 month (r=0.62, p=0.03) and 3 months (r=0.71, p=0.01).ConclusionThe number of the anterior chamber particles graded using anterior segment optical coherence tomography after the procedure correlates with the IOP-lowering effect of SLT.

scholarly journals Applications of Scheimpflug Imaging in Glaucoma Management: Current and Potential Applications

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Alexander T. Nguyen ◽  
Tiffany Liu ◽  
Ji Liu
Keyword(s):  
Intraocular Pressure ◽  
Image Reconstruction ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Three Dimensional ◽  
Biomechanical Properties ◽  
Scheimpflug Imaging ◽  
Potential Applications ◽  
Corneal Biomechanical Properties

Scheimpflug photography is the basis for a variety of imaging devices that are highly versatile. The applications of Scheimpflug imaging are wide in scope, spanning from evaluation of corneal ectasia to quantifying density in nuclear sclerotic cataracts. The potential uses for Scheimpflug-based devices are expanding and a number of them are relevant in glaucoma. In particular, they can provide three-dimensional image reconstruction of the anterior segment which includes assessment of the iridocorneal angle. Photographic analyses allow also for a noncontact method of estimating central corneal thickness (CCT) and intraocular pressure (IOP), as well as the study of various corneal biomechanical properties, which may be useful for stratifying glaucoma risk.

scholarly journals Evaluation of Corneal Biomechanical Properties Modification after Small Incision Lenticule Extraction Using Scheimpflug-Based Noncontact Tonometer

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Leonardo Mastropasqua ◽  
Roberta Calienno ◽  
Manuela Lanzini ◽  
Martina Colasante ◽  
Alessandra Mastropasqua ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Corneal Biomechanics ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Lenticule Extraction ◽  
Noncontact Tonometer ◽  
Corneal Biomechanical Properties

Purpose.To quantify the effect of small incision lenticule extraction (SMILE) on the corneal biomechanics using Scheimpflug noncontact tonometer (Corvis ST).Methods.Twenty eyes of twenty patients, evaluated as eligible for surgery, with high myopia and/or moderate myopic astigmatism, underwent small incision lenticule extraction (SMILE). All patients underwent Corvis ST preoperatively and postoperatively after 1 week, and 1 and 3 months to observe alterations of corneal biomechanical properties. The main outcome measures were Deformation Amplitude, 1st-AT, and 2nd-AT. The relationship between the amount of stroma removed and the percentage variation of the measured parameters from baseline was evaluated with generalized linear model from each time point. For completeness also intraocular pressure (IOP), central corneal thickness (CCT), and their variations after surgery were evaluated.Results.The ratio between the amount of removed refractive error and, respectively, changes of Deformation Amplitude, 1st-AT, and 2nd-AT were significantly modified at the 1st week after surgery(P=0.005; P=0.001; P=0.024). At 1 and 3 months these values did not show statistically significant alterations. Intraocular pressure and central corneal thickness showed statistically significant changes during follow-up.Conclusions.No significant modifications in biomechanical properties were observed after SMILE so this procedure could induce only minimal transient alterations of corneal biomechanics.

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