Angle-Closure Glaucomas (original) (raw)
Related papers
Angle-closure glaucomas — posterior (pushing) mechanisms other than pupillary block
Hong Kong Journal of Ophthalmology, 2007
Angle-closure is often erroneously considered synonymous with pupillary block, the most common mechanism leading to acute or chronic iridocorneal apposition. However, abnormalities exist in structures and/or forces other than those related to pupillary block and may cause apposition despite a patent iridotomy. A 4-point classification of these mechanisms has been described, and includes mechanisms originating in the ciliary body, lens, or posterior segment. This review outlines the characteristics of angle-closure specific to each of these 3 levels.
Angle Closure Glaucoma: Pathogenesis and Evaluation. A Review
Journal of Clinical & Experimental Ophthalmology, 2012
Pupillary block is the most common mechanism responsible for angle closure [9], but the anatomical configuration which causes a plateau iris may be a more common mechanism than was previously thought. Pupillary block mechanism In pupillary block, the resistance to aqueous flow from the posterior to anterior chamber is at the level of the pupil, creating a pressure gradient that causes forward bowing of the peripheral iris and closure of the angle [10,11]. Aqueous humor flow from the posterior chamber into the anterior chamber is regulated by a differential pressure between the anterior and the posterior chamber. This pressure differential may increase greatly when the dimensions of the iris-lens channels are changed. As this pressure increment increases, the iris becomes more convex and can close angle. Extreme anterior iris-bulging, iris bombé would be expected with pressure differentials of 10-15 mm Hg [12]. The variables that influence the flow through the ''pinch region'' (iris-lens channels) and influence the pressure differential and related iris contour have been studied extensively [12-16]. Changes in pupillary size, increased channel length and decreased height, movement of the iris insertion posteriorly or of the lens anteriorly, were associated with an expected increase in the pressure differential. Other variables exist and interact to determine the iris contour, including eye size, especially the dimensions of the anterior segment, lens size and position, iris stroma and iris musculature characteristics, ciliary body anatomy, and physiologic parameters including aqueous humor flow rate, facility of outflow, vitreousaqueous fluid flow, and the effects of accommodation and blinking [9].
Angle-closure Glaucoma: The Role of the Lens in the Pathogenesis, Prevention, and Treatment
Survey of Ophthalmology, 2009
Primary angle-closure glaucoma is a major cause of blindness worldwide. It is a disease of ocular anatomy that is related to pupillary-block and angle-crowding mechanisms of filtration angle closure. Eyes at increased risk for primary angle-closure are small with decreased axial length, anterior chamber depth, and filtration angle width, associated with a proportionately large lens. Angle-closure glaucoma afflicts Asian and
Angle closure glaucoma – misleading causes, delayed treatment
Archive of Clinical Cases, 2016
We present the clinical case of a 43 years old female patient, referred to our clinic for a red, painful left eye. Multiple bilateral similar attacks were reported by the patient in the last 2 years, for which a diagnosis of conjunctivitis or anterior uveitis was established. At current presentation we found bilateral marked inflammatory reaction in the anterior segment (extensive peripheral iris synechiae, inflammatory membrane in the pupillary area, iris "bombe", pigment dispersion, but no keratic precipitates or cells in the anterior chamber. Intraocular pressure (IOP) was 12 mmHg in OD and 40 mmHg in OS, under topical treatment, started 24 before the current visit. Gonioscopy showed closed angle in both eyes, "openable" in various grades after indentation in all quadrants. Anterior segment ocular coherence tomography (AS-OCT) and ultrasonic biomicroscopy (UBM) suggested anatomical causes for acute angle closure, revealing multiple rolling folds on the iris surface, high insertion onto the scleral wall. Multiple laboratory investigations excluded any potential cause of uveitis, therefore the anatomical theory remained in discussion related to a disproportion between anterior structures leading to angle closure attacks. We performed laser peripheral iridotomy, in this patient with positive outcome: IOP decrease, deepening of the AC, open angle in gonioscopy. Misleading issues in this case confused the initial diagnosis and delayed the adequate treatment.
Update on angle-closure glaucoma: diagnosis
Revista Da Associacao Medica Brasileira, 2014
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Clinical & Experimental Ophthalmology, 2012
Primary angle‐closure glaucoma (PACG) frequently leads to severe vision loss. Prevalence among older Asian populations is high and given global demographics, the number of persons with PACG will increase dramatically in the coming decades. Improvements in imaging of the anterior segment will help us to identify more of those with angle closure, and important clinical trials that are currently underway will provide important evidence to support screening and treatment approaches for PACG. In this manuscript, we intend to review the existing evidences, to introduce some important on‐going studies on PACG and to share the experience and viewpoints of the authors.
Ophthalmic Ultrasonography and Ultrasound Biomicroscopy
Mechanisms and treatment of primary angle closure: a review
Clinical & Experimental Ophthalmology, 2012
Angle closure can recur following peripheral iridotomy in up to 58% of cases, due to plateau iris syndrome, lens disproportion or ciliary block. Ciliary block glaucoma is an important differential diagnosis of shallow anterior chamber, angle closure and high intraocular pressure, which may occur spontaneously or following laser or surgery. Some underlying mechanisms of ciliary block glaucoma remain poorly understood but lens-ciliary body apposition and anterior hyaloid changes with increased hydraulic resistance are major pathogenic factors. An understanding of the pathogenic factors facilitates early recognition of ciliary block glaucoma, and aids a logical sequence of intervention. We review the mechanisms of post-iridotomy angle closure and propose a stepwise treatment strategy for these conditions.
Misdiagnosis of angle closure glaucoma
BMJ, 2006
Angle closure glaucoma is a sight threatening ophthalmic emergency. Patients classically present with an acutely painful red eye and periocular headache, loss of vision, nausea, and vomiting, but sometimes the presentation is less dramatic or more systemic than ocular. The diagnosis may be missed in such cases, leading to unnecessary investigations, delayed treatment, and blindness. We describe three cases of angle closure glaucoma in which initial diagnostic uncertainty led to a delay in treatment and which highlight the need for a wider awareness of this condition. Case reports Case 1 A 66 year old woman was admitted to the orthopaedic ward for elective spinal canal decompression for spinal stenosis. She was otherwise healthy and was taking oral diclofenac, morphine, and amitriptyline. During the operation, she was placed prone for spinal laminectomy. Postoperatively, she received regular opiate analgesia. On the third postoperative day the patient developed severe headache, photophobia, and neck stiffness without focal neurological deficit. An urgent computed tomography scan of the head was normal. On the fourth postoperative day she complained of visual loss, a red eye was noted, and an ophthalmology referral was made. Her visual acuity was counting fingers for both eyes. Slit lamp examination was hampered by her immobility, but both eyes were red with cloudy corneas; shallow anterior chambers; fixed, middilated pupils; and high intraocular pressures of 45 mm Hg in the right eye and 33 mm Hg in the left eye (normal < 21 mm Hg). A diagnosis of bilateral angle closure glaucoma was made. She was treated immediately with the standard medical regimen (using eye drops to constrict the pupil and systemic acetazolamide to lower the intraocular pressure). Her amitriptyline was stopped, as it was a potential precipitating factor. Her response to medical treatment was partial, and, as she had coexistent cataracts, bilateral lens extraction, lens implantation, and surgical peripheral iridotomies were done. The anterior chambers deepened immediately, and the intraocular pressures normalised postoperatively. Two months later, intraocular pressures were normal without treatment. The best corrected Snellen visual acuity was only 6/12 in either eye, with bilateral visual field constriction and reduced colour vision associated with glaucomatous optic atrophy (fig 1).