Cataract, phacoemulsification and intraocular pressure: Is the anterior segment anatomy the missing piece of the puzzle?

Solano, Marissé Masís; Lin, Shan

doi:10.1016/j.preteyeres.2018.01.003

Cited by 39 publications

(34 citation statements)

References 59 publications

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“…The OHTS study reports that removal of the crystalline lens in cataract surgery decreases postoperative IOP by > 4.0 mm Hg (16%) ( Mansberger et al, 2012 ). Clinical evidence indicates that cataract surgery reduces IOP ( Masis Solano and Lin, 2018 ) and that the IOP reduction can persist long-term ( Fig. 7 ).…”

Section: Clinical Science: An Aqueous Outflow Pump That Fails In Glaucomamentioning

confidence: 99%

Aqueous outflow regulation – 21st century concepts

Johnstone

Chen

Tan

et al. 2021

Progress in Retinal and Eye Research

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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.

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Section: Clinical Science: An Aqueous Outflow Pump That Fails In Glaucomamentioning

confidence: 99%

Aqueous outflow regulation – 21st century concepts

Johnstone

Chen

Tan

et al. 2021

Progress in Retinal and Eye Research

View full text Add to dashboard Cite

show abstract

“…One possible explanation for this lack of studies is the achievement of sufficient reduction of IOP reduction or the number of medications needed is considered to be difficult in the absence of phacoemulsification. It is widely known that cataract surgery itself has a lowering effect on IOP and the number of medications needed in glaucoma patients [24][25][26][27][28][29][30]. However, a consensus has not been reached regarding the indications for this type of surgery.…”

Section: Introductionmentioning

confidence: 99%

Twelve-month surgical outcome and prognostic factors of stand-alone ab interno trabeculotomy in Japanese patients with open-angle glaucoma

et al. 2021

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The purpose of the study was to evaluate the 12-month surgical outcome and prognostic factors of stand-alone ab interno trabeculotomy. The changes in the intraocular pressure (IOP) and medication score and the success rate of the surgery were analyzed. Thirty-four eyes of 29 patients with primary open-angle glaucoma (POAG; n = 16) or pseudoexfoliation glaucoma (PEG; n = 18) with a 12-month follow-up period were included in the study. The decreases in IOP and medication score from the baseline to the all-time-point were statistically significant (P < 0.001). The surgical success rates were 97.1%, 76.5%, and 44.0% at 3 months (90 days), 6 months (180 days), and 12 months (365 days), respectively. A mixed effect Cox model revealed that the type of glaucoma (POAG) was significantly associated with surgical failure (P = 0.044). Furthermore, the surgical success rate was significantly higher in eyes with PEG than it was in those with POAG (P = 0.019). Stand-alone ab interno trabeculotomy significantly lowered both the IOP and the medication score in patients with glaucoma, although almost one quarter of the cases needed additional glaucoma surgeries. The surgical success rate was significantly higher in eyes with PEG than it was in those with POAG.

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“…Despite being a significant risk factor for OAG progression, IOP changes post cataract surgery remain poorly understood. The mechanism(s) behind IOP reduction post cataract removal have several interconnected theories: (1) the anterior chamber anatomy changes, as the intraocular lens (IOL) is significantly thinner than the crystalline lens; (2) the anterior chamber deepens, the width of anterior chamber increases enabling higher volume of aqueous humour to reach trabecular meshwork; and (3) the resistance in trabecular meshwork also decreases and the ciliary body and its’ processes change position leading to decreased IOP 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Importantly, most of the studies concerning ACA and IOP change after cataract surgery investigated closed angle glaucoma 23 – 25 . The main mechanisms related to these changes were ACA opening and increased aqueous drainage through the trabecular meshwork 2 . The reduction of IOP was also observed in eyes with OAG 11 – 21 .…”

Section: Introductionmentioning

confidence: 99%

Changes in ocular morphology after cataract surgery in open angle glaucoma patients

Pakulienė

Kuzmienė

Siesky

et al. 2021

Sci Rep

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The purpose of this study was to evaluate intraocular pressure (IOP) pre- and postoperatively, together with anterior chamber angle (ACA) parameters and biometrical results in cataract patients with or without open angle glaucoma (OAG). The prospective observational case–control study included 15 eyes with cataract and OAG in the glaucoma group and 25 eyes with only cataract in control group. Examination included full ophthalmic evaluation, IOP, ocular biometry and anterior segment optical coherence tomography measuring ACA pre- and 6 months postoperatively. OAG patients had a larger absolute IOP reduction compared to control group. Anterior chamber depth (ACD) and ACA width significantly increased in both groups. The OAG group had a tendency of narrower ACA preoperatively, but overall ACA parameters did not differ in either group pre- and postoperatively. The ACD change after surgery correlated with ACA parameters in the control group, but not in OAG group. Axial length was shorter postoperatively in the control group, but remained similar in the OAG group. Absolute IOP reduction was more pronounced in cataract patients with OAG than in cataract patients without glaucoma. ACD and ACA postoperatively increased in both groups and AL shortening was observed in non-OAG in cataract group.

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Cataract, phacoemulsification and intraocular pressure: Is the anterior segment anatomy the missing piece of the puzzle?

Cited by 39 publications

References 59 publications

Aqueous outflow regulation – 21st century concepts

Aqueous outflow regulation – 21st century concepts

Twelve-month surgical outcome and prognostic factors of stand-alone ab interno trabeculotomy in Japanese patients with open-angle glaucoma

Changes in ocular morphology after cataract surgery in open angle glaucoma patients

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