Reduction in Intraocular Pressure after Cataract Extraction: The Ocular Hypertension Treatment Study

Abstract

Purpose To determine the change in intraocular pressure (IOP) after cataract extraction in the Observation Group of the Ocular Hypertension Treatment Study (OHTS). Design Comparative case series Participants Forty-two participants (63 eyes) who underwent cataract surgery in at least one eye during the study and a control group of 743 participants (743 eyes) who did not undergo cataract surgery Methods We defined the “split date” as the study visit date that cataract surgery was reported in the cataract surgery group, and a corresponding date in the control group. Preoperative IOP was defined as the mean IOP of up to 3 visits prior to split date. Postoperative IOP was the mean IOP of up to 3 visits including the split date (0, 6, and 12 months with ‘0 months’ equaling the split date). In both groups, we censored data after initiation of ocular hypotensive medication, or glaucoma surgery of any kind. Main outcome measures Difference in preoperative and postoperative IOP. Results In the cataract group, postoperative IOP was significantly lower than the preoperative IOP (19.8 ± 3.2 mmHg vs. 23.9 ± 3.2 p<0.001). The postoperative IOP remained lower than preoperative IOP for at least 36 months. The average decrease in postoperative IOP from preoperative IOP was 16.5%, and 39.7% of eyes had postoperative IOP ≥ 20% below preoperative IOP. A greater reduction in postoperative IOP occurred in the eyes with the highest preoperative IOP. In the control group, the corresponding mean IOP’s were 23.8 ± 3.6 prior to the split date and 23.4 ± 3.9 after the split date. Conclusion Cataract surgery decreases IOP in ocular hypertensive patients over a long period of time.

Cataract Surgery and Intraocular Pressure

“…Since then, and particularly in the last decade, many studies have consistently shown a variable IOP decrease after cataract surgery (table 1) [5,6,7,8,9,10,11,12,13,14,15,16,17,18]. …”

Role of Lens Extraction In Glaucoma – A Review

“…greater response seen in eyes with higher preoperative pressures. 15 For PACG eyes, the IOP response is much more and ranges from 2-8mmHg with a mean reduction of 6mmHg documented by a recent report released by American Academy of Ophthalmology (AAO). [16][17][18][19][20]10 Comparative studies between POAG and PACG subsets have clearly documented better response in ACG group in terms of IOP control and number of medications required, occurring despite a pre-existing patent laser iridotomy thus negating the aspect of relieving pupil block element as the sole cause.…”

“…23 For those cases with poor control of pressure, IOP reduction after cataract surgery depends on height of pre-op values with a linear correlation irrespective of glaucomatous optic nerve changes. 5,9,15,25 Thus a decision to undertake a lens extraction alone needs to be individually tailored depending on target pressure, patient profile, adherence to medication and accessibility to medical care. Long term control of IOP is possible and two recent multicentre study groups (iStent study group and OHTS) have documented IOP reduction of 8.5 and 4mmHg post-phacoemulsification in the control arm over a follow up of 1-3 years.…”

“…Long term control of IOP is possible and two recent multicentre study groups (iStent study group and OHTS) have documented IOP reduction of 8.5 and 4mmHg post-phacoemulsification in the control arm over a follow up of 1-3 years. 32,15 A word of caution however as upto 26% patients may require additional medications, laser treatment or glaucoma surgery within a year of lens extraction.…”

Evaluation of efficacy of lens extraction for intraocular pressure reduction in eyes with primary angle closure glaucoma and primary angle closure

“…In the 1970s, Bigger and Becker reported a lower IOP after cataract extraction in glaucoma patients [7].…”