Outcomes of Cataract Extraction in Eyes With PAC
Outcomes of Cataract Extraction in Eyes With PAC
Purpose: To examine the clinical outcomes of cataract extraction in eyes with primary angle closure (PAC) and coexisting cataract.
Patients and Methods: Retrospective study of surgical outcomes after phacoemulsification and intraocular lens implantation in 55 eyes of 39 patients with PAC or occludable angles and visually symptomatic cataract. Approximately, 61.8% of eyes had received a peripheral iridotomy and 65% had evidence of glaucomatous optic neuropathy (GON).
Results: At 7.2 months after cataract extraction, a statistically significant reduction in intraocular pressure (IOP) was observed in all eyes with PAC (median 3 mm Hg, P =<0.0001). The reduction in IOP was significantly greater in eyes with a higher preoperative IOP (P =<0.0001). On average, one less glaucoma medication was in use postoperatively (P =0.01). Eyes with >180 degrees of peripheral anterior synechiae (PAS) preoperatively achieved a significantly greater reduction in IOP postoperatively compared with those with less PAS (7.5 vs. 4.4 mm Hg, P =0.03). The observed reduction in IOP in eyes with PAC and GON was significantly greater compared with those without GON (5.6 vs. 2.5 mm Hg, P =0.01). Visual acuity was significantly improved after cataract extraction by a mean of −0.23 LogMAR units (P =0.0001).
Conclusions: Contrary to earlier expectations, the observed reduction in postoperative IOP in eyes with PAC was significantly greater in the presence of a higher preoperative IOP, a larger number of glaucoma medication, narrower iridotrabecular angle width, and greater extent of PAS formation and in eyes with evidence of GON. Lens extraction seems to have a beneficial effect on IOP control in PAC, and is especially efficacious in more advanced cases.
Primary angle closure glaucoma (PACG) accounts for half of all glaucoma blindness worldwide. Primary angle closure (PAC) occurs as a result of crowded anterior segment anatomy, causing appositional contact between the peripheral iris and trabecular meshwork. The most common underlying mechanism is pupil block.
Laser peripheral iridotomy (PI) is accepted as highly effective in preventing symptomatic acute pressure rises in PAC sufferers who have had one episode in their fellow eye. Reports suggest that PI is not universally effective in preventing asymptomatic intraocular pressure (IOP) rises in the longer term. Angle width increases in most eyes after PI, but between 20% and 25% of eyes, show no change. Furthermore, studies of laser PI in the treatment of PAC suggest that the presence of 180 degrees or more of circumferential peripheral anterior synechiae (PAS) is indicative of a significantly greater likelihood of poor IOP control, as are eyes with established glaucomatous optic neuropathy (GON). Many ophthalmologists would therefore consider trabeculectomy, with its inherent risks and complications, as the treatment of choice in more advanced PACG.
The crystalline lens plays a pivotal role in the pathogenesis of PAC. The cardinal anatomic characteristic in eyes with PAC is a thicker, more anteriorly positioned crystalline lens than in unaffected eyes. It is therefore no surprise that lens extraction has been proposed as a method of managing IOP in PAC instead of a filtering procedure. Currently, there is little evidence from randomized or nonrandomized studies of the role of clear lens extraction in the management of PACG.
One randomized controlled trial of laser PI versus phacoemulsification in eyes with previous acute PAC found that mean angle width was significantly greater and mean IOP significantly lower, in the group that had undergone phacoemulsification. A recent randomized controlled trial found combined phacotrabeculectomy with adjunctive mitomycin C to be only marginally more effective than phacoemulsification alone in controlling IOP in medically controlled chronic angle closure glaucoma eyes with coexisting cataract; however, combined surgery was associated with more complications (P <0.001), additional surgery, and more progression of optic neuropathy (P =0.03). The report did not describe the performance of phacoemulsification in different grades of severity of angle closure.
In this retrospective study we examined the hypothesis that IOP control in PAC is poorer in those with evidence of more advanced disease after lens extraction. The effect of cataract extraction on IOP control in patients with PAC and the association between change in IOP and preoperative factors determining the severity of PAC was explored.
Abstract and Introduction
Abstract
Purpose: To examine the clinical outcomes of cataract extraction in eyes with primary angle closure (PAC) and coexisting cataract.
Patients and Methods: Retrospective study of surgical outcomes after phacoemulsification and intraocular lens implantation in 55 eyes of 39 patients with PAC or occludable angles and visually symptomatic cataract. Approximately, 61.8% of eyes had received a peripheral iridotomy and 65% had evidence of glaucomatous optic neuropathy (GON).
Results: At 7.2 months after cataract extraction, a statistically significant reduction in intraocular pressure (IOP) was observed in all eyes with PAC (median 3 mm Hg, P =<0.0001). The reduction in IOP was significantly greater in eyes with a higher preoperative IOP (P =<0.0001). On average, one less glaucoma medication was in use postoperatively (P =0.01). Eyes with >180 degrees of peripheral anterior synechiae (PAS) preoperatively achieved a significantly greater reduction in IOP postoperatively compared with those with less PAS (7.5 vs. 4.4 mm Hg, P =0.03). The observed reduction in IOP in eyes with PAC and GON was significantly greater compared with those without GON (5.6 vs. 2.5 mm Hg, P =0.01). Visual acuity was significantly improved after cataract extraction by a mean of −0.23 LogMAR units (P =0.0001).
Conclusions: Contrary to earlier expectations, the observed reduction in postoperative IOP in eyes with PAC was significantly greater in the presence of a higher preoperative IOP, a larger number of glaucoma medication, narrower iridotrabecular angle width, and greater extent of PAS formation and in eyes with evidence of GON. Lens extraction seems to have a beneficial effect on IOP control in PAC, and is especially efficacious in more advanced cases.
Introduction
Primary angle closure glaucoma (PACG) accounts for half of all glaucoma blindness worldwide. Primary angle closure (PAC) occurs as a result of crowded anterior segment anatomy, causing appositional contact between the peripheral iris and trabecular meshwork. The most common underlying mechanism is pupil block.
Laser peripheral iridotomy (PI) is accepted as highly effective in preventing symptomatic acute pressure rises in PAC sufferers who have had one episode in their fellow eye. Reports suggest that PI is not universally effective in preventing asymptomatic intraocular pressure (IOP) rises in the longer term. Angle width increases in most eyes after PI, but between 20% and 25% of eyes, show no change. Furthermore, studies of laser PI in the treatment of PAC suggest that the presence of 180 degrees or more of circumferential peripheral anterior synechiae (PAS) is indicative of a significantly greater likelihood of poor IOP control, as are eyes with established glaucomatous optic neuropathy (GON). Many ophthalmologists would therefore consider trabeculectomy, with its inherent risks and complications, as the treatment of choice in more advanced PACG.
The crystalline lens plays a pivotal role in the pathogenesis of PAC. The cardinal anatomic characteristic in eyes with PAC is a thicker, more anteriorly positioned crystalline lens than in unaffected eyes. It is therefore no surprise that lens extraction has been proposed as a method of managing IOP in PAC instead of a filtering procedure. Currently, there is little evidence from randomized or nonrandomized studies of the role of clear lens extraction in the management of PACG.
One randomized controlled trial of laser PI versus phacoemulsification in eyes with previous acute PAC found that mean angle width was significantly greater and mean IOP significantly lower, in the group that had undergone phacoemulsification. A recent randomized controlled trial found combined phacotrabeculectomy with adjunctive mitomycin C to be only marginally more effective than phacoemulsification alone in controlling IOP in medically controlled chronic angle closure glaucoma eyes with coexisting cataract; however, combined surgery was associated with more complications (P <0.001), additional surgery, and more progression of optic neuropathy (P =0.03). The report did not describe the performance of phacoemulsification in different grades of severity of angle closure.
In this retrospective study we examined the hypothesis that IOP control in PAC is poorer in those with evidence of more advanced disease after lens extraction. The effect of cataract extraction on IOP control in patients with PAC and the association between change in IOP and preoperative factors determining the severity of PAC was explored.
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