Glaucoma Surgery

Minimally invasive glaucoma surgery (MIGS) has become increasingly popular as a step in the management pathway of open angle glaucoma. Due to the relative novelty of these devices, there remains some paucity of evidence relating to their long-term efficacy and safety, and this can make comparison between these techniques somewhat complex. This review article aims to guide clinical decision making by providing the latest evidence on the comparative efficacy of current iterations of minimally invasive glaucoma surgery. A literature review was conducted to identify the most significant recent evidence to support the safety and efficacy of the various forms of minimally invasive glaucoma surgery. Included studies provided efficacy and safety data on a variety of minimally invasive glaucoma surgery methods. The PubMed database was searched and a total of 484 studies, published between 2015 and 2020 were identified, of which 27 were included. The studies indicate that most available forms of minimally invasive glaucoma surgery show statistically significant efficacy in terms of intraocular pressure reduction and improvement in medication burden, while maintaining an acceptable safety profile.

Objective: To evaluate the change of biomechanical properties of the trabecular meshwork (TM) and configuration of collector channels (CC) by high-resolution optical coherence tomography (HR-OCT) induced by Schlemm's canal (SC) dilation. Methods: The anterior segments of two human eyes were divided into four quadrants. One end of a specially designed cannula was placed in SC and the other end connected to a perfusion reservoir. HR-OCT provided three-dimensional (3D) volumetric and two-dimensional (2D) cross-sectional imaging permitting assessment of the biomechanical properties of the TM. A large fluid bolus was introduced into SC. Same-sample, pre and post deformation and disruption of SC and CC lumen areas were analyzed. Results: Morphologic 3D reconstructions documented pressure-dependent changes in lumen dimension of SC, CC, and circumferential intrascleral channels. 2D imaging established volumetric stress-strain curves (elastance curves) of the TM in quadrants. The curves of TM elastance shift to the right with an increase in pressure-dependent steady-state SC area. After a bolus disruption, the SC area increased, while the CC area decreased. Conclusion: Our experimental setup permits the study of the biomechanical properties of TM by examining elastance, which differs segmentally and is altered by mechanical expansion of SC by a fluid bolus. The study may shed light on mechanisms of intraocular pressure control of some glaucoma surgery.

Objective-This study was carried out to evaluate the usefulness of endoscopy for examination of the anterior and posterior segments of the glaucomatous eyes. Animals: Fifteen dogs. Methods: Ocular examination was done using endoscopic probe (8.5mm diameter, Eickemeyer video endoscope unit supplied with halogen light source 150 watt (vetlux), Germany). The animals were sedated through intravenous injection of Xylazine (1mg/Kg body weight, ADWIA, Egypt). Surface corneal anesthesia was achieved by local application of Benox® (Benoxinate Hydrochloride 4mg, EIPICO, Egypt) to the eye under investigation. After sedation, the endoscopic probe was applied on the cornea and videos were monitored on the laptop and diagnostic images were captured and processed. Results: Primary open angle glaucoma was diagnosed in 2 cases. Goniodysgenesis with closure of the iridocorneal angle (ICA) by an iris like sheet was seen in 2 cases. Abnormal thickening of the pectinate ligament with closure of the ICA was observed in one case. Lens induced glaucoma was the most common type of the glaucoma seen in the presented cases (10 cases); phacomorphic glaucoma due to lens displacement was diagnosed in 5 cases, phacoanaphylactic glaucoma secondary to cataractous lens was diagnosed in 3 cases while pupillary block glaucoma (due to swelling of the cataractous lens) was seen in 2 cases. Conclusion: endoscopy is non invasive technique for diagnosis of glaucoma in dogs in which interior visualization of the eye is impossible such in cases with corneal edema and cataract. [Abd-Elhamid M.A, Ali K.M and Ayman A. Mostafa. Endoscopic evaluation for the anterior and posterior segment of the eye: A new and useful technique for diagnosis of glaucoma in dogs. Life Sci J 2014;11(11):233-237]. (ISSN:1097-8135). http://www.lifesciencesite.com. 33

Medical Glaucoma is a major cause of blindness. It affect quality of life of patients. So the present study was carried out in ESI Hopital, Jaipur with the aim to assess quality of life of glaucoma patients as per WHOQOL-Bref. Along with assessment of quality of life of patients various socio-demographic and clinical associates of this quality of life was also found. It was observed that quality of life of glaucoma patients was lowered in all four domains i.e. Physical, Mental, Social and Environmental. Among socio-demographic variables, quality of life was not found to be associated with sex and marital status but it was found more poorer in elder age groups and low socio-economic status. Among clinical variables its quality of life of glaucoma patients was not found to be associated with papillary reaction, Anterior chamber depth (ACD), type of glaucoma and duration of glaucoma  but it was found more poorer in glaucoma patients with pain, congestion and defective visual equity. Quality of life was significantly lowered in sever glaucoma. Glaucoma patients should be educated to realize the severity of the disease and importance of the adherence to daily treatment.

Trabecular meshwork (TM) motion abnormality is the leading cause of glaucoma. With technique limitations, how TM moves is still an enigma. This study describes a new laboratory platform to investigate TM motion responses to ocular transients in ex vivo eyes. The anterior segments of human cadaver and primate eyes were mounted in a perfusion system fitting. Perfusion needles were placed to establish mean baseline pressure. A perfusion pump was connected to the posterior chamber and generated an immediate transient pressure elevation. A phase-sensitive optical coherent tomography system imaged and quantified the TM motion. The peak-to-peak TM displacements (ppTMD) were determined, a tissue relaxation curve derived, and a time constant obtained. This study showed that the ppTMD increased with a rise in the pulse amplitude. The ppTMD was highest for the lowest mean pressure of 16 mmHg and decreased with mean pressure increase. The pulse frequency did not significantly change ppTMD. With a fixed pulse amplitude, an increase in mean pressure significantly reduced the time constant of recoil from maximum distension. Our research platform permitted quantitation of TM motion responses to designed pulse transients. Our findings may improve the interpretation of new TM motion measurements in clinic, aiding in understanding mechanisms and management.

Purpose: To compare the effect on intraocular pressure (IOP) of phacoemulsification combined with viscosynechialysis and trabe-culotomy with that of phacoemulsification combined with trabecu-lectomy in eyes with primary angle-closure glaucoma (PACG) and visually significant cataract. Setting:

Purpose
The aim of the study was to evaluate the effi cacy and safety of decapsulation of the fi brous capsule
around the valve body versus valve reimplantation in another site in refractory glaucoma cases.
Patients and methods
We studied 25 cases with refractory glaucoma that had been implanted with an Ahmed
glaucoma valve; their intraocular pressure (IOP) was greater than 21 mmHg and had undergone
additional maximum topical antiglaucoma therapy. Patients were divided into two groups
according to the surgical treatment that had been performed: group I included 12 eyes that
had been treated by surgical decapsulation of the cyst around the valve body without removal
of the valve and group II included 13 eyes treated by removal of the valve and reimplantation
in another quadrant of the eye.
Results
Of the 25 patients included in the study, 15 were male and 10 were female, with a mean
age of 19.2 ± 9.2 years in group I and 22.1 ± 10.3 years in group II. Recurrent congenital
glaucoma was the most common preoperative diagnosis in both groups (50 and 53.8% in
groups I and II, respectively). There was no statistically signifi cant difference between the two
groups regarding preoperative patient demographic characteristics (P < 0.05). The surgical
results revealed that the mean operation time was signifi cantly lower in group I than in group II
(30 ± 12 and 45 ± 13.5 min, respectively; P = 0.023). However, there were no statistically
signifi cant differences in the success (complete and partial) and failure rates between the
two groups (P < 0.05). There was marked reduction in IOP from preoperative values in both
groups but there were no signifi cant differences in IOP levels between the two groups over
the follow-up visits. Tube-related complications occurred in group II only and included corneal
tube touch in one (7.7%) case and erosion of the tube covering in two (15.4%) cases. One
of them developed endophthalmitis and then lost the perception of light (PL) and ended in
phthisis bulbi. Recurrence of encapsulation occurred more in group I (three cases, 25%) than
in group II (two cases, 15.4%), after a mean postoperative time of 23 ± 2 weeks. The incidence
of valve re-encapsulation was statistically insignifi cant between the two groups (P = 0.09).
Conclusion
Both surgical techniques were effective in controlling IOP in cases with encapsulated Ahmed
valve; however, the decapsulation technique was simpler with shorter operation time and no
probability for tube-related complications. Although the other technique of valve reimplantation
had a longer operation time and more tube-related complications, it was associated with less
incidence of re-encapsulation. However, larger multicenter studies with longer follow-up are
needed for validation of these treatment strategies.
Keywords:
ahmed glaucoma valve, decapsulation, refractory glaucoma

We examined the role of common genetic variation in schizophrenia in a genome-wide association study of substantial size: a stage 1 discovery sample of 21,856 individuals of European ancestry and a stage 2 replication sample of 29,839 independent subjects. The combined stage 1 and 2 analysis yielded genome-wide significant associations with schizophrenia for seven loci, five of which are new (1p21.3, 2q32.3, 8p23.2, 8q21.3 and 10q24.32-q24.33) and two of which have been previously implicated (6p21.32-p22.1 and 18q21.2). The strongest new finding (P = 1.6 × 10(-11)) was with rs1625579 within an intron of a putative primary transcript for MIR137 (microRNA 137), a known regulator of neuronal development. Four other schizophrenia loci achieving genome-wide significance contain predicted targets of MIR137, suggesting MIR137-mediated dysregulation as a previously unknown etiologic mechanism in schizophrenia. In a joint analysis with a bipolar disorder sample (16,374 affected individuals a...

Purpose To make an account of published implant-related complications (IRC) by a systematic review of the literature. Methods A systematic search of Pubmed and Scopus databases and Google Scholar engine was performed with selection criteria to detect papers on IRC. We excluded unrelated papers and reviewed selected ones. We considered papers that did not explicitly state about occurrence or not occurrence of IRC as non-IRC reporting. Main outcome measures were the number of papers reporting on complications, IRC, and types of IRC. Results After the search, selection, and addition, we studied 109 papers. Incidence of IRC was 4.5%, half required explantation. While 26 implant studies found IRCs (23%), 13 case reports on surgical complications, 8 (61.5%) of them reported IRC. Frequent complications were conjunctival erosion, blockage of the tube, migration to anterior chamber or damage to surrounding tissues. Conclusion Most papers did not report on IRC. Length or nature of studies may skew finding IRC. The incidence of IRC was 4.5%. Hard and sharp implants carry a greater risk of IRC and explantation.

Aims: To review the trends in glaucoma procedural treatments from January 2009
to December 2017. Methodology: A retrospective search was carried out from the
operating theater and laser room records of the Eye Foundation Hospitals in Lagos,
Abuja, and Ijebu‑Imushin. Consecutive glaucoma procedures for each year from
January 2009 to December 2017 were recorded in the data sheet prepared for the
study. Data were analyzed using SPSS version 25. Results: From 2009 to 2017,
trabeculectomy had been decreasing in frequency from 117 to 65 (44%), except for
2015. The frequency of use of glaucoma drainage device (GDD) has been steadily
increasing from 1 in 2013 to 26 in 2017, but this is not statistically significant.
The frequency of cataract extraction with trabeculectomy reduced drastically from
20 in 2009 to 3 (566%) in 2014. Bleb review (BR) increased from 2 in 2009 to
18 (800%) in 2015, however, it dropped to 6 in 2017 (66%). Among the laser
procedures, transscleral cyclophotocoagulation (g‑probe) is commonly done. It
increased from 40 procedures in 2009 to 98 in 2014 (145%). There has been an
increase in laser trabeculoplasty from 15 in 2009 to 44 in 2013 (193%). Laser
iridotomy increased from 12 in 2009 to 26 in 2015 (116%). From 2009 to 2015,
there was an increase in glaucoma procedures and surgeries – 206 to 325 (58%)
but this declined by 27% from 2015 to 2017. Conclusion: Trabeculectomy is the
most performed procedure at our centers. This is followed by g‑probe and laser
trabeculoplasty. The rate of trabeculectomy is on the decrease, while the rate of
GDD is increasing. The laser procedures are also on the increase.
Keywords: Eye Foundation Hospital Group, glaucoma surgeries, trends, types

Intraocular pressure (IOP) is the only treatable risk factor in glaucoma, one of the world's leading causes of blindness. Mechanisms that maintain IOP within a normal range have been poorly understood in contrast to intrinsic mechanisms that regulate systemic blood pressure. Vessel walls experience continuous pulse-induced cyclic pressure and flow. Pressure-dependent wall stress and flow-dependent shear stress provide sensory signals that initiate mechanotransduction responses. The responses optimize vessel wall elasticity, compliance and lumen size, providing a feedback loop to maintain intrinsic pressure homeostasis. Aqueous humor is part of a vascular circulatory loop, being secreted into the anterior chamber of the eye from the vasculature, then returning to the vasculature by passing through the trabecular meshwork (TM), a uniquely modified vessel wall interposed between the anterior chamber and a vascular sinus called Schlemm's canal (SC). Since pressure in circulatory loops elsewhere is modulated by cyclic stresses, one might predict similar pressure modulation in the aqueous outflow system. Recent laboratory evidence in fact demonstrates that cyclic IOP changes alter aqueous outflow while increasing cellularity and contractility of TM cells. Cyclic changes also lead to alterations in gene expression, changes in cytoskeletal networks and modulation of signal transduction. A new technology, phase-based optical coherence tomography, demonstrates in vivo pulse-dependent TM motion like that elsewhere in the vasculature. Recognition of pulse-dependent TM motion provides a linkage to well-characterized mechanisms that provide pressure homeostasis in the systemic vasculature. The linkage may permit unifying concepts of pressure control and provide new insights into IOP homeostatic mechanisms.

Purpose: To describe an adjustable suture (AS) experimental model that allows for tightening, loosening and retightening of the suture tension in trabeculectomy. Methods: Standard trabeculectomy was performed in fifteen pig eyeballs. All pig eyes were tested twice: one test with conventional suture in both flap’s corners (conventional suture group) and another test with a conventional suture at one corner and an adjustable suture in the other corner (AS group). The order in which each test was performed was defined by randomization. Intraocular pressure was measured at three time points: T1) when the knots were tightened; T2) when the AS was loosened or the conventional knot was removed; and T3) when the AS was retightened in the AS group or five minutes after the knot removal in the conventional suture group.
Results: The mean Intraocular pressure was similar between the two groups at time point 1 (p=0.97). However, significant Intraocular pressure differences were found between eyes in the conventional and adjustable suture groups at time points 2 (12.6 ± 4.2 vs 16.3 ± 2.3 cmH2O, respectively, p=0.006) and 3 (12.2 ± 4.0 vs 26.4±1.7cmH2O,respectively;p=0.001).Whiletheconventionaltechniqueallowed only Intraocular pressure reduction (following the knot removal; T2 and T3), the AS technique allowed both Intraocular pressure reduction (T2) and elevation (T3) through the management (loosening and retightening) of the suture. conclusion: This experimental model provides an effective noninvasive posto- perative mechanism of suture tension adjustment.

Purpose: To compare the results of trabeculectomy with subconjunctival Bevacizumab and 5-Fluorouracil (5-FU); with trabeculectomy with 5-FU alone; in terms of intraocular pressure (IOP) lowering, bleb formation, and complications, in the long term.

We report the use of a high-resolution optical coherence tomography (OCT) imaging platform to identify and quantify pressure-dependent aqueous outflow system (AOS) tissue relationships and to infer mechanical stiffness through examination of tissue properties in ex vivo human eyes. Five enucleated human eyes are included in this study, with each eye prepared with four equal-sized quadrants, each encompassing 90 degrees of the limbal circumference. In radial limbal segments perfusion pressure within Schlemm's canal (SC) is controlled by means of a perfusion cannula inserted into the canal lumen, while the other end of the cannula leads to a reservoir at a height that can control the pressure in the can-nula. The OCT system images the sample with a spatial resolution of about 5 μm from the trabecular meshwork (TM) surface. Geometric parameters are quantified from the 2D OCT images acquired from the sample subjected to controlled changes in perfusion pressures; parameters include area and height of the lumen of SC, collector channel entrances (CCE) and intrascleral collector channels (ISCC). We show that 3D OCT imaging permits the identification of 3-D relationships of the SC, CCE and ISCC lumen dimensions. Collagen flaps or leaflets are found at CCE that are attached or hinged at only one end, whilst the flaps are connected to the TM by cylindrical structures spanning SC. Increasing static SC pressures resulted in SC lumen enlargement with corresponding enlargement of the CCE and ISCC lumen. Pressure-dependent SC lumen area and height changes are significant at the 0.01 levels for ANOVA, and at the 0.05 for both polynomial curves and Tukey paired comparisons. Dynamic measurements demonstrate a synchronous increase in SC, CCE and ISCC lumen height in response to pressure changes from 0 to 10, 30 or 50 mm Hg, respectively, and the response time is within the 50-millisecond range. From the measured SC volume and corresponding IOP values, we demonstrate that an elastance curve can be developed to infer the mechanical stiffness of the TM by means of quantifying pressure-dependent SC volume changes over a 2 mm radial region of SC. Our study finds pressure-dependent motion of the TM that corresponds to collagen leaflet configuration motion at CCE

Purpose To assess the efficacy and safety of the XEN Gel Stent in patients with primary open-angle glaucoma. Materials and methods Twenty eyes of 17 patients (6 males, 11 females) with primary open-angle glaucoma were implanted with XEN Gel Stent. The following data were ascertained in each participant at baseline and at 1, 3, 6, 9 and 12 months following implanting procedure: intraocular pressure, number of anti-glaucoma medications, retinal sensitivity (PS 24/2 w/w), pattern electroretinogram (ISCEV standard), as well as the number of complications. Results The mean intraocular pressure reduction in a 1-year follow-up was 18% (21.56 vs. 17.69 mmHg, p 

MATERIAL Y MÉTODO. Estudio descriptivo retrospectivo de 15 ojos (14 pacientes), para evaluar el control de la PIO en glaucomas refractarios, mediante el implante de una válvula de Ahmed. Los casos se siguieron durante al menos seis meses, y nueve de ellos se siguieron durante un año. Se evaluó el control de la PIO y las complicaciones que aparecieron.

RESULTADOS. La PIO previa media al implante fue de 35,46 mmHg (22-56). Tras la cirugía, la PIO media fue: a la semana 16,06 mmHg (3-45), al mes 22,46 mmHg (11-56), a los tres meses 24,53 mmHg (6-56), a los seis meses 21,6 mmHg (5-52) y, en los nueve casos seguidos un año, de 22,4 mmHg (3-56). El 66,66% de los casos requirieron tratamiento tópico complementario. Se registró un caso de hipotonía precoz, un caso de extrusión del tubo del implante y un caso en el que hubo que recolocar la válvula. No encontramos ningún caso de hipema. La PIO se controló en el 66,66% de los casos a los seis meses, y en el 77,77% al año.

We propose an integrated model of aqueous outflow control that employs a pump-conduit system in this article. Our model exploits accepted physiologic regulatory mechanisms such as those of the arterial, venous, and lymphatic systems. Here, we also provide a framework for developing novel diagnostic and therapeutic strategies to improve glaucoma patient care. In the model, the trabecular meshwork distends and recoils in response to continuous physiologic IOP transients like the ocular pulse, blinking, and eye movement. The elasticity of the trabecular meshwork determines cyclic volume changes in Schlemm’s canal (SC). Tube-like SC inlet valves provide aqueous entry into the canal, and outlet valve leaflets at collector channels control aqueous exit from SC. Connections between the pressure-sensing trabecular meshwork and the outlet valve leaflets dynamically control flow from SC. Normal function requires regulation of the trabecular meshwork properties that determine distention and recoil. The aqueous pump-conduit provides short-term pressure control by varying stroke volume in response to pressure changes. Modulating TM constituents that regulate stroke volume provides long-term control. The aqueous outflow pump fails in glaucoma due to the loss of trabecular tissue elastance, as well as alterations in ciliary body tension. These processes lead to SC wall apposition and loss of motion. Visible evidence of pump failure includes a lack of pulsatile aqueous discharge into aqueous veins and reduced ability to reflux blood into SC. These alterations in the functional properties are challenging to monitor clinically. Phase-sensitive OCT now permits noninvasive, quantitative measurement of pulse-dependent TM motion in humans. This proposed conceptual model and related techniques offer a novel framework for understanding mechanisms, improving management, and development of therapeutic options for glaucoma.

Trabecular meshwork (TM) motion abnormality is the leading cause of glaucoma. With technique limitations, how TM moves is still an enigma. This study describes a new laboratory platform to investigate TM motion responses to ocular transients in ex vivo eyes. The anterior segments of human cadaver and primate eyes were mounted in a perfusion system fitting. Perfusion needles were placed to establish mean baseline pressure. A perfusion pump was connected to the posterior chamber and generated an immediate transient pressure elevation. A phase-sensitive optical coherent tomography system imaged and quantified the TM motion. The peak-to-peak TM displacements (ppTMD) were determined, a tissue relaxation curve derived, and a time constant obtained. This study showed that the ppTMD increased with a rise in the pulse amplitude. The ppTMD was highest for the lowest mean pressure of 16 mmHg and decreased with mean pressure increase. The pulse frequency did not significantly change ppTMD. With a fixed pulse amplitude, an increase in mean pressure significantly reduced the time constant of recoil from maximum distension. Our research platform permitted quantitation of TM motion responses to designed pulse transients. Our findings may improve the interpretation of new TM motion measurements in clinic, aiding in understanding mechanisms and management.

Primary angle closure glaucoma (PACG) is a major cause of blindness worldwide. We conducted a genome-wide association study (GWAS) followed by replication in a combined total of 10,503 PACG cases and 29,567 controls drawn from 24 countries across Asia, Australia, Europe, North America, and South America. We observed significant evidence of disease association at five new genetic loci upon meta-analysis of all patient collections. These loci are at EPDR1 rs3816415 (odds ratio (OR) = 1.24, P = 5.94 × 10(-15)), CHAT rs1258267 (OR = 1.22, P = 2.85 × 10(-16)), GLIS3 rs736893 (OR = 1.18, P = 1.43 × 10(-14)), FERMT2 rs7494379 (OR = 1.14, P = 3.43 × 10(-11)), and DPM2-FAM102A rs3739821 (OR = 1.15, P = 8.32 × 10(-12)). We also confirmed significant association at three previously described loci (P…

Purpose: To review the results of the Moorfields Safer Surgery System (MSSS) for trabeculectomy, recently introduced in Malta. Methods: Patient files were reviewed from data collected over an 18 month period, from Mater Dei Hospital. Files of all patients undergoing primary trabeculectomy with a minimum of 12 months follow up data available were reviewed. Primary outcome measure of success was defined as a 30% drop in final post-operative intraocular pressure (IOP) at 1 year. The secondary outcome measure of success was a final post-op IOP of less than 21mmHg. Unqualified success was defined as a satisfactory IOP without the need of anti-glaucoma medication, while qualified success was defined as a satisfactory IOP in those patients requiring anti-glaucoma medication. Results: 43 eyes (mean age = 66.2 yrs ± 11.7) were analysed. The mean pre-operative IOP was 27.0mmHg ± 4.6. The mean post-op IOP at one year was 15.3mmHg ±2.7. Unqualified success for the primary outcome measure was achieved in 64.1% of patients while the qualified success was achieved in 82.1%. Unqualified success for the secondary outcome measure was achieved in 72.7%, while a qualified success of 94.8% was obtained. There was a 6.8% failure rate. Conclusions: The results from this first review using the Moorfields safe surgery system for Trabeculectomy surgery in the Maltese islands compares well to the current literature.

Introduction: To develop a grading system that provides objective quantification of flow through the conventional aqueous humor out- flow (AHO) system. The technique gives clinicians an additional assessment option in the evaluation of glaucoma treatment approaches.

Methods: This was a retrospective observational study. This study evaluated the eyes of all primary open-angle glaucoma patients who under- went a Trabectome (NeoMedix Corp., Tustin, CA, USA) procedure with or without cataract surgery in the interval between April and September 2016 (n = 73). The nasal hemisphere was divided into three regions. Utilizing a four- level grading system designed for this study, an aqueous humor outflow grade (G0–G3) was assigned to each region using a video taken during examinations. The individual grade levels of the three regions were combined to get a composite AHO score. The correlation between the composite AHO score and intraocular pressure (IOP) was then analyzed. Additionally, the speed of red blood cell (RBC) clusters in the episcleral veins (ESV) was calculated when made possible by the existence of pulsatile flow.

Results: At 3 months following the Trabectome procedure, average IOP decreased from 26 to 15 mmHg. Assessment of the relationship between AHO grade and IOP demonstrated that a high composite AHO score was correlated with lowered IOP (Tukey-Kramer method p \ 0.05). Additionally, it was found that if one of the three regions had an AHO grade of C G2, an IOP of \ 20 mmHg could be predicted. (Fischer’s exact test p\0.0001). Calculated speed was as follows: at G1, the speed was 0.68 ± 0.26 mm/s (n = 7), at G2, the speed was 1.8 ± 0.84 mm/s (n = 5), and at G3, the speed was 6.8 ± 3.3 mm/s (n = 6).

Conclusion: There was a significant correlation between an increase in the composite AHO score and a decrease in IOP. Additionally, the speed of RBC clusters as they traveled through the ESVs remained consistent for each of the grades, and the span of the speeds from lower to higher grades represented a significant range. These findings suggest that the grading system is a reliable measure of AHO.

Primary open-angle glaucoma remains one of the leading causes of irreversible blindness in the world. Intraocular pressure (IOP) is the only known treatable risk factor.  Treatment of glaucoma remains imperfect because our understanding of IOP regulation is incomplete.  The abnormality of IOP regulation is thought to reside in the outflow side of the system.  The traditional view has been that aqueous outflow is passive, regulated by modulation of the extracellular matrix of the juxtacanalicular space of the aqueous outflow system. Despite many decades of study based on the passive conceptual framework, the cause of glaucoma remains an enigma.  Lack of causal clarity is not merely an academic concern, but rather has serious clinical implications for both medical and surgical glaucoma management.  This chapter reviews a new conceptual framework based on recent evidence.  This alternative framework or model portrays aqueous outflow regulation as under the control of dynamic pressure-dependent tissue motion that regulates fluid passage through valve-like structures in Schlemm's canal and at collector channel entrances.