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The Special Sense Organs and Their Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
The hollow eyeball is divided into three cavities: the anterior chamber located between the iris and cornea; the vitreous chamber, the space behind the lens that contains the vitreous humor; and the posterior chamber between the iris, lens, and vitreous chamber. The other chambers of the eye are filled with aqueous humor, which is secreted by the ciliary processes and reabsorbed into the venous system through the canal of Schlemm (Figure 13.3).
Mycotic Keratitis Caused by Dematiaceous Fungi
Published in Mahendra Rai, Marcelo Luís Occhiutto, Mycotic Keratitis, 2019
Javier Araiza, Andrés Tirado-Sánchez, Alexandro Bonifaz
Morphology: The most frequent clinical findings are ulcers with a whitish to white-yellowish corneal pitting, ciliary congestion, edema, corneal infiltration mainly in the peripheral part of the ulcer, presence of an immune ring in the border of the ulcer, hypopyon (Garg et al. 2000, Balne et al. 2012, Karsten et al. 2012), palpebral edema, conjunctival injection, quimosis, epithelial lesions with “feathered” borders, anterior chamber inflammation with stroma infiltrated in the surface area, anterior, medium or deep surrounded by edema, Descemet folds, mild iritis (Thomas 2003) endophthalmitis and pigmented brown lesions (by the pigment characteristic of black fungi) in stroma, which are reported in 6 to 27% of the cases. In other cases, subluxated cataracts with posterior and vitreous haemorrhage, corneal infiltration with overlapping obscure pigmentation have been reported in the posterior chamber in up to 14.5% (Hsiao et al. 2014). Furthermore, an obscure haze (particulate material) in the eye fundus, uveitis, thinning of the cornea, epithelial defects and a rare corneal perforation have been reported; the ulcers can vary in size from 1 to 12 mm. The clinical aspect of the majority of the lesions is not determinant to establish that this is MK, so it is essential to analyze the samples to establish the correct and timely diagnosis (Guarro et al. 1999, Garg et al. 2000, Martone et al. 2011, Chaidaroon et al. 2015, Lalremruata and Sud 2015, Chaidaroon et al. 2016, Calvillo-Medina et al. 2018).
Anterior vitrectomy
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Occasionally, a dense pupillary membrane is encountered in an eye after distant surgery or trauma. The following procedure uses a combined anterior and posterior approach and can be used in an aphakic eye or in the presence of an anterior chamber lens (but not a posterior chamber lens). This so-called ‘chopping block’ technique is useful for very dense membranes.
Current Concepts of the Uveitis-Glaucoma-Hyphema (UGH) Syndrome
Published in Current Eye Research, 2023
Meera S. Ramakrishnan, Kenneth J. Wald
Glaucoma is by far the least appreciated pathology of the triad for a number of reasons. First, many eyes afflicted with UGH are managed with corticosteroids for long periods and therefore “steroid response” pressure elevation is assumed in many cases. Second, erythroclastic induced pressure rises from hyphema are typically obvious but transient. Finally, glaucoma in UGH is classically thought to be due to chronic changes to the angle due to ACIOL footplates and any associated synechiae. However, in the modern age, it is likely that most cases of UGH-based IOP elevation have none of the above etiologies. More likely is a clinically well-positioned posterior chamber IOL situated in the “ciliary sulcus” (anterior to the lens capsule) or fixated to sclera or iris where it can interact with uveal structures. In this case, the iris chafing and continuous inflammation leads to extravasation of protein from chronic blood-ocular barrier breakdown. This can be low grade and typically not clinically detectable. Hence, since the anatomic disturbance is subtle, the evolving glaucoma may not be readily attributed to an UGH mechanism. More severe blood ocular barrier breakdown will be observed by the clinician as aqueous cells or protein induced flare, but mild breakdown with low volume of protein and no cell will have no clinical signs hence go undetected.
Visual and refractive outcomes following secondary intraocular lens implantation
Published in Seminars in Ophthalmology, 2022
Marina Delgado João, Jorge Vasco Costa, Keissy Sousa, Tiago Monteiro, Nuno Lopes, Gil Calvão-Santos, Carlos Cruz, Fernando Vaz
In this study, all iris-claw aphakic IOLs were implanted in a prepupillary position. Nonetheless, retropupillary iris-claw IOLs have been increasing in popularity among surgeons for aphakia correction in eyes with insufficient capsular or zonular support. The rationale is based on some factors: the retropupillary position is more physiological since it is closer to the nodal point, the risk of bullous keratopathy due to endothelial cell loss is lower due to the greater distance to the cornea, greater IOP reduction, and lower risk of CME.19 However, a recent meta-analysis20 which included six studies (five retrospective case series and one randomized controlled clinical trial) compared the visual and safety outcome of anterior chamber vs. posterior chamber iris-claw IOL implantation. The authors concluded that the visual outcomes of both techniques were similar and no statistically significant differences were found in CDVA and endothelial cell count. Nonetheless, prepupillary iris-claw IOLs were associated with less IOP reduction and a relative increase of CME. Our study had similar CDVA, IOP reduction, and CME to those described in these studies.20,21
Local ocular renin–angiotensin–aldosterone system: any connection with intraocular pressure? A comprehensive review
Published in Annals of Medicine, 2020
Mervi Holappa, Heikki Vapaatalo, Anu Vaajanen
From the posterior chamber, AH flows between the lens and the iris into the anterior chamber after which it can be excreted either through the trabecular or uveoscleral pathways. A novel so-called uveolymphatic pathway has also been described, which may even be a target for new glaucoma treatments [172,181]. In addition, AH can exit the eye via iris vessels, corneal endothelium and anterior vitreous body [181,182] but their significance to AH dynamics is minimal. In the trabecular pathway, which is the main route of drainage, AH flows through the porous, AH filtering trabecular meshwork, the endothelial lining of Schlemm’s canal itself, the collecting channels and aqueous veins into the circulatory system [158,166,172]. This process is known to be passive with the AH movement being driven by the pressure gradient (IOP) [168,181,183]. The actin cytoskeleton and the adhesions of trabecular meshwork cells affect the fluid outflow but the rate limiting step is considered to be the flow through the endothelium in the inner wall of Schlemm’s canal [168,184–188].