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Sustained decrease in IOP seen after cataract extraction in eyes without glaucoma
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Researchers described a 2-year sustained decrease in IOP in nonglaucomatous Asian eyes after cataract extraction, a decrease that also occurred in the fellow eye after subsequent cataract surgery, in a study recently published in the British Journal of Ophthalmology.
At a single center, the National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore, the authors reviewed 116 consecutive nonglaucomatous patients with senile cataract who underwent sequential cataract extractions by a single surgeon.
IOPs were recorded preoperatively and postoperatively at day 1, day 30, day 90, 6 months, 1 year and 2 years, according to the study. Once the fellow eye underwent cataract extractions, IOP was recorded at the same time points. Patient mean age was 70.6 years, with 50 males (43.1%) and 66 females (56.9%).
Researchers reported that, prior to cataract extraction, mean IOP in the first eye was 15.4 ± 2.6 mm Hg and 15.2 ± 2.5 mm Hg in the fellow eye. IOP at baseline varied from 10.0 mm Hg to 21.0 mm Hg in both eyes.
After cataract surgery, IOP decreased to a mean of 14.0 ± 3.1 mm Hg at 1 month, with a significant decrease in IOP at subsequent follow-ups, according to researchers.
Researchers found a mean decrease in IOP from 1.6 mm Hg (8.6%) to 2.3 mm Hg (14.0%).
Compared to the initial IOP measurement, the fellow eye showed no significant decrease in IOP.
After cataract surgery in the fellow eye, the mean IOP decreased to a level comparable with that of the first surgical eyes at all follow-up intervals, with a decrease of comparable magnitude until 1 year, they reported.
A subset of 46 patients underwent phacoemulsification in one eye and extracapsular cataract extraction (ECCE) in the other. Researchers found no significant difference in the IOP-lowering effect of phacoemulsification compared with ECCE and no significant difference comparing the entire cohort to eyes that had phacoemulsification or ECCE.
Researchers found a statistically significant mean IOP decrease of approximately 2.0 mm Hg after cataract surgery.
Finally, those with the greatest presurgical IOPs experienced a greater magnitude of decrease in IOP, and in those with the lowest presurgical IOP, postsurgical levels remained relatively unchanged.
“We described a 2-year sustained and statistically significant decrease in IOP after cataract extraction, which also occurs in the fellow eye when cataract surgery is subsequently performed to that eye,” the researchers concluded. “The decrease in IOP may be a useful adjunct in the control of IOP in patients.” – by Abigail Sutton
Disclosure: Ngo reported no relevant financial disclosures. Please see the full study for a list of all remaining authors’ relevant financial disclosures.
Perspective
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Carl H. Jacobsen, OD, FAAO
Cataract surgery has been recently found to have a modest intraocular pressure lowering effect. Ngo and colleagues in their retrospective analysis of post-cataract surgery patients have furthered our understanding of this interesting phenomena.
First and perhaps most importantly, they found that the IOP lowering effect of cataract surgery persists for at least 2 years. Additionally, they have confirmed previous reports that patients with higher pre-surgery IOP have a greater post-surgery IOP lowering effect. In this study, patients with pre-surgery IOP greater than 17 mm Hg realized an IOP lowering of about 20%.
There are many challenges in glaucoma management. Medical treatment is plagued by problems such as tachyphylaxis, poor compliance and side effects. Laser treatment is only modestly effective and often short-lived. Glaucoma surgery carries sight threatening potential risks.
With this backdrop, it is heartening to know that our post-cataract surgery patients may enjoy not just clearer vision, but also a modest and persistent IOP lowering effect.
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