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Editors Selection IGR 20-4

Surgical Treatment: Anterior chamber depth after phacoemulsification

Comment by Clement Tham on:

48122 Anterior chamber depth, iridocorneal angle width, and intraocular pressure changes after phacoemulsification: narrow vs open iridocorneal angles, Huang G; Gonzalez E; Peng PH et al., Archives of Ophthalmology, 2011; 129: 1283-1290

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Huang et al. (1724) compared the changes in anterior chamber depth, iridocorneal angle width, and intraocular pressure (IOP) after cataract extraction by phacoemulsification in eyes with open angles (OAs) and narrow angles (NAs) in a prospective study. OAs were defined as those with Shaffer grades of three or four in three or all four quadrants. Eyes with NAs were defined as those with Shaffer grades of two or less in three or all four quadrants. The existence or extent of peripheral anterior synechiae (PAS) before surgery was not addressed in the recruitment criteria. Huang et al. found that after phacoemulsification, there were significantly greater increase in angle opening distance (AOD) 500, greater increase in anterior chamber depth, and greater reduction in IOP, in the NA group compared to the OA group. They concluded postoperative reduction in IOP was proportional to the increase in angle in both groups, but the IOP reduction per 0.1-mm increase in AOD500 in NA eyes was greater than that in OA eyes. In real-life clinical situations, one has to be cautious in applying the conclusions from this study to predict clinical outcomes. In eyes with pre-existing PAS or trabecular dysfunction, the amount of IOP reduction after phacoemulsification may be decreased, despite significant increases in anterior chamber depth and iridocorneal angle width. It has long been known that cataract removal may reduce IOP in eyes with primary angle closure (PAC) and primary angle-closure glaucoma (PACG), but it remains to be determined what pre-operative clinical parameters in these patients could reliably predict IOP outcomes. Whether such IOP reduction could be sustained in the long term also remains to be seen. This paper by Huang et al. is a good starting point in our understanding of the relationship between cataract extraction, anterior segment anatomical parameters, and IOP. More research needs to be done to identify those patients, especially those with existing glaucomatous optic neuropathy, in whom other surgical interventions may be needed in addition to phacoemulsification.

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