Understanding Trabecular Meshwork Physiology: A Key to the Control of Intraocular Pressure?

Physiology ◽  
2003 ◽  
Vol 18 (5) ◽  
pp. 205-209 ◽  
Author(s):  
Artur Llobet ◽  
Xavier Gasull ◽  
Arcadi Gual
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Aqueous Humor ◽  
Trabecular Meshwork ◽  
Anterior Chamber Angle ◽  
Chamber Angle

The trabecular meshwork is a tissue located in the anterior chamber angle of the eye, and it is a crucial determinant of intraocular pressure values because of its resistance to the evacuation of aqueous humor from the eye. Here we bring together classical and recent discoveries on the function of the trabecular meshwork, keys to understanding eye pathophysiology.

Anterior Chamber Angle and Iris-Lens Contact Alteration During Pupillary Dilation

2011 ◽  
Author(s):  
Sara Jouzdani ◽  
Rouzbeh Amini ◽  
Victor H. Barocas
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Aqueous Humor ◽  
Ciliary Body ◽  
Ocular Tissue ◽  
Posterior Chamber ◽  
Pupillary Dilation ◽  
Anterior Chamber Angle ◽  
Aqueous Outflow ◽  
Chamber Angle

The aqueous humor (AH) provides oxygen and nutrients for the avascular ocular tissue specifically, the cornea and lens. AH is secreted by the ciliary body into the posterior chamber, passes through pupil, and drains into the anterior chamber (Fig. 1a). Resistance to the aqueous outflow generates the intraocular pressure (IOP), which is 15–20 mmHg in the normal eyes.

Glaucoma Problems Associated with Aniridia

2010 ◽  
Author(s):  
Peter A. Netland
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Trabecular Meshwork ◽  
Ciliary Body ◽  
Vision Loss ◽  
Visual Field Loss ◽  
Anterior Chamber Angle ◽  
Foveal Hypoplasia ◽  
Closed Angle ◽  
Chamber Angle

Glaucoma is a potentially vision-threatening problem that is commonly encountered in aniridia patients. This condition may develop at birth, or shortly thereafter. More commonly, however, glaucoma is acquired later in childhood or even young adulthood. If unrecognized and untreated, glaucoma can result in blindness. For this reason, it is important to be vigilant in watching for this condition in children affected with aniridia. Vision lost due to glaucomatous damage cannot be regained at a later time. In addition to glaucoma, children with aniridia may demonstrate other problems with their vision. They may have refractive errors, corneal or retinal problems, or abnormalities of eye movement. Foveal hypoplasia (lack of development of the retina) may limit vision in some children. In aniridia patients, cataract (opacification or cloudiness of the lens) is seen with approximately the same prevalence as glaucoma. Cataract, however, differs from glaucoma in that the vision loss due to cataract is reversible. Glaucoma is suspected in aniridia patients when there is an increased intraocular pressure. Glaucoma can be definitely diagnosed when changes of the optic nerve occur due to this elevated intraocular pressure. At the later stages of the disease, visual field loss occurs. In the normal eye, the fluid (aqueous humor) in the front of the eye (the anterior chamber) is produced by the ciliary body, which is located behind the iris (see Figure 5.1). The fluid produced from the ciliary body flows forward into the anterior chamber, where it drains from the anterior chamber angle through tissue called the trabecular meshwork. When there is an abnormal situation, the fluid exits the eye poorly or not at all, and the intraocular pressure may be increased. The fluid may be blocked from exiting the eye by a closed angle, or may flow poorly out of the eye even though the angle is open (see Figure 5.2). The angle may be closed in aniridic patients when the stump of residual iris covers the trabecular meshwork in the anterior chamber angle.

Changes in intraocular pressure and anterior chamber angle after congenital cataract extraction

2019 ◽  
Vol 23 (4) ◽  
pp. e30-e31 ◽  
Author(s):  
Jylan Gouda ◽  
Abdelrahman Elhusseiny ◽  
Reham H. Tomairek ◽  
Dina Elfayoumi ◽  
Ahmed Awadein ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Congenital Cataract ◽  
Cataract Extraction ◽  
Anterior Chamber Angle ◽  
Chamber Angle

Anterior Chamber Angle and Trabecular Meshwork Measurements Made by Fourier-domain Optical Coherence Tomography in Healthy White Children

2017 ◽  
Vol 26 (9) ◽  
pp. 810-815 ◽  
Author(s):  
José I. Fernández-Vigo ◽  
Lucía De-Pablo-Gómez-de-Liaño ◽  
Cristina Fernández-Vigo ◽  
Gabriel Arcos-Villegas ◽  
Cristina Fernández-Pérez ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Anterior Chamber ◽  
Trabecular Meshwork ◽  
Fourier Domain ◽  
Optical Coherence ◽  
Anterior Chamber Angle ◽  
White Children ◽  
Chamber Angle

scholarly journals The changes of anatomic and topographic characteristics of eye anterior segment after uncomplicated cataract phacoemulsification

2013 ◽  
Vol 94 (6) ◽  
pp. 853-858
Author(s):  
A A Ryabtseva ◽  
M P Yugaj ◽  
N S Nikitina
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Ultrasound Biomicroscopy ◽  
Anterior Chamber Angle ◽  
Ciliary Processes ◽  
Lens Implantation ◽  
Topographic Characteristics ◽  
Chamber Angle

Aim. To study the changes of anatomic and topographic characteristics of the eye anterior segment after uncomplicated cataract phacoemulsification using corneal incision with intraocular soft lens implantation. Methods. The data of ultrasound biomicroscopy and noncontact tonometry of 58 eyes (56 patients, 32 females, 24 males aged 54 to 78 years) before and after cataract phacoemulsification were analyzed. Paitents with survived ocular trauma, refractive keratoplasty, glaucoma, uveitis, and surgical complications (incomplete capsulorrhexis, posterior capsule rupture, ciliary zonule disinsertion, corneal burn). Apart from the common examinations (visual acuity testing, tonometry, tonography, eye A- and B-ultrasonography, biomicroscopy), all patients underwent eye ultrasound biomicroscopy. Results. Anterior chamber depth increased from 2.73±0.10 to 4.17±0.06 mm (p ≤0.001). Trabecula-iris distance measured at 500 μm from the scleral spur, increased from 0.38±0.02 to 0.47±0.02 mm (p ≤0.001). Anterior chamber angle increased from 28.69±1.87 to 42.73±1.56 degrees (p ≤0.001), the angle between the iris and the sclera increased from 32.78±1.39 to 41.36±0.84 degrees (p ≤0.001), the angle between the sclera and ciliary processes increased from 39.48±1.29 to 45.30±1.16 degrees (p ≤0.001). Intraocular pressure according to the non-contact tonometry data decreased from 18.16±1.29 to 13.55±0.95 mm Hg (p ≤0.001). Conclusion. Anterior chamber depth, trabecula-iris distance, anterior chamber angle, the angle between sclera and iris and the angle between sclera and ciliary processes increased significantly after phacoemulsification with intraocular lens implantation. Intraocular pressure decreased significantly according to the non-contact tonometry data.

scholarly journals Anterior Chamber Angle Evaluation following Phakic Posterior Chamber Collamer Lens with CentraFLOW and Its Correlation with ICL Vault and Intraocular Pressure

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Sherif A. Eissa ◽  
Sherin H. Sadek ◽  
Mohamed W. A. El-Deeb
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Refractive Error ◽  
Case Series ◽  
Mean Value ◽  
Posterior Chamber ◽  
Anterior Chamber Angle ◽  
Implantable Collamer Lens ◽  
Angle Width ◽  
Chamber Angle

Purpose.To assess intraocular pressure (IOP), lens vaulting, and anterior chamber (AC) angle width, following V4C implantable Collamer lens (ICL) procedure for myopic refractive error.Methods.A prospective case series that enrolled 54 eyes of 27 patients that were evaluated before and after V4C phakic posterior chamber Collamer lens implantation for correction of myopic refractive error. Preoperative measurement of IOP was done using Goldmann applanation tonometer and anterior chamber angle width using both Van Herick slit lamp grading system and Scheimpflug tomography imaging (Oculus Pentacam). Follow-up of the aforementioned variables was at 1, 6, and 18 months postoperatively, together with ICL vault measurements.Results.The mean baseline IOP of11.69±2.15showed a statistically significant (P=0.002) increase after 1 month that remained unchanged at 6 and 18 months postoperatively, with mean value of16.07±4.12,16.07±4.10, and16.07±4.13, respectively. Pentacam AC angle width showed a statistically significant decrease at 1(P=0.025), 6(P=0.016), and 18(P=0.010)months postoperatively, with mean preoperative value of40.14±5.49that decreased to25.28±5.33,25.46±5.44, and25.49±5.38, at 1, 6, and 18 months, respectively. Mean ICL vault showed moderate correlation with Pentacam AC angle width at 1(r=-0.435)and 6(r=-0.424)months.Conclusion. V4C ICL implantation resulted in decrease in AC angle width and increase in IOP, within acceptable physiological values at all time points.

scholarly journals Assessment of anterior chamber angle changes after phacoemulsification with swept-source OCT

2021 ◽  
Vol 14 (10) ◽  
pp. 1527-1532
Author(s):  
Qian Zheng ◽  
◽  
Zhang-Liang Li ◽  
Ping-Jun Chang ◽  
Yun-E Zhao ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Cataract Surgery ◽  
Anterior Chamber ◽  
Anterior Chamber Depth ◽  
Anterior Chamber Angle ◽  
Swept Source ◽  
Narrow Angle ◽  
Significant Difference ◽  
Shallow Anterior Chamber ◽  
Chamber Angle

AIM: To assess the changes of anterior chamber angle in patients with shallow anterior chamber after phacoemulsification combined with intraocular lens (IOL) implantation, based on anterior segment swept-source optical coherence tomography (AS-SS-OCT) measurements. METHODS: This was a prospective case control study; sixty eyes of sixty case were scheduled for cataract surgery with normal intraocular pressure (IOP). Based on anterior chamber depth (ACD) and gonioscopy findings, the eyes were divided into two groups: group of shallow anterior chamber and narrow angle (SAC group, 30 eyes); and group of normal anterior chamber group with wide angle (NAC group, 30 eyes). Measurements of ACD, anterior chamber volume (ACV), iris volume (IV), lens vault (LV), angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), and trabecular iris angle (TIA) were conducted in each group before and 3mo after surgery. RESULTS: There was no significant difference in age, axial length (AL), corneal curvature, corneal diameter, intraocular pressure, and IV between two groups before surgery, except for the LV (P=0.000). ACD and ACV were prominently larger in the NAC group than the SAC group 3mo after operation (3.69±0.38 vs 3.85±0.39 mm, P=0.025; 161.37±19.47 vs 178.26±20.30 mm3, P=0.002). AOD750, ARA750 in nasal and inferior quadrants, TISA750 in all quadrants except temporal, and TIA750 in all quadrants in SAC group were significantly smaller than those in NAC group after operation (all P<0.05). CONCLUSION: Cataract surgery can deepen anterior chamber and increase the width of anterior chamber angle in Chinese subjects, but the angle related parameters including AOD750, ARA750, TISA750, TIA, TISA750, and ACV in patients with shallow anterior chamber and narrow angle do not reach the normal level.

scholarly journals THE HISTOLOGICAL STUDY OF THE STRUCTURES OF THE ANTERIOR CHAMBER ANGLE IN THE CHILDREN OF DIFFERENT GESTATIONAL AGE UNDER THE NORMAL CONDITIONS AND IN THE PRESENCE OF CONGENITAL GLAUCOMA

2017 ◽  
Vol 12 (2) ◽  
pp. 87-90
Author(s):  
Marina Andreevna Zertsalova ◽  
E. P Fedotova ◽  
V. V Brzheskiy ◽  
R. A Nasirov
Keyword(s):  
Anterior Chamber ◽  
Gestational Age ◽  
Trabecular Meshwork ◽  
Histological Study ◽  
Full Term ◽  
Fibrous Membrane ◽  
Congenital Glaucoma ◽  
Anterior Chamber Angle ◽  
Histological Picture ◽  
Chamber Angle

Purpose. The objective of the present study was to obtain and investigate the tissue samples taken from the anterior chamber angle of the children of different gestational age under the normal conditions and in the presence of congenital glaucoma; the secondary objective was to carry out the histological study of the pieces of tissues removed from the glaucoma patients of different gestational age undergoing hypotensive filtration surgery (sinusotrabeculectomy). Materials and methods. The anterior chamber angle histological preparations from a total of five enucleated eyes were available for the intravital investigation of the trabecular meshwork (two of them were obtained from the full-term infants and one from a premature baby). Results. The histological study of the structures of the anterior chamber angle of the enucleated eyes has demonstrated the presence in all the cases of cornea, Descemet’s membrane, trabecular meshwork, Schlemm’s canal, and iris. The morphological structure of the anterior chamber angle associated with congenital glaucoma shows up some peculiar features compared with the normal one, such as its block by the permanent fibrous membrane which penetrates deep into the trabecular meshwork that, in its turn, is formed from the rough and thickened tissue. The histological picture of the fetal eye at different gestational age exhibits the open anterior chamber angle, the well developed porous trabecular meshwork, and fragmentation of Descemet’s membrane near the trabecular meshwork. No signs of fibrous degeneration of the trabecule have been apparent. Conclusion. The intravital investigation of the trabecular meshwork has demonstrated some peculiar features that differ depending on the gestational age in birth. In the full-term babies, it is hypoplastic and covered with the rough fibrous membrane at certain places. Its histological picture is similar to that of the preparations of the enucleated eyes. In the premature babies, the trabecular meshwork is fibrous and characterized by enhanced cellularity; it undergoes fibrous degeneration that becomes apparent after the birth of the premature child (it is supposed to be related to the proliferative processes inherent in such babies).

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