Can Cataract Surgery Cause Glaucoma?
Cataract surgery does not cause glaucoma, but it can cause temporary elevations in intraocular pressure (IOP) in the immediate postoperative period, particularly in patients with pre-existing open-angle glaucoma. 1
Immediate Postoperative IOP Elevation
The primary concern is early postoperative IOP spikes, not the development of glaucoma itself:
- In patients with open-angle glaucoma undergoing cataract surgery alone, 69% experienced IOP rises of 10 mmHg or more on postoperative day 1, with 77% having absolute IOP over 25 mmHg. 2
- Mean IOP increased from 18.9 mmHg preoperatively to 34.2 mmHg on postoperative day 1 in glaucoma patients undergoing cataract extraction alone. 2
- This represents a transient complication requiring careful monitoring and therapy, not the development of new glaucoma. 2
Long-Term IOP Effects: Beneficial, Not Harmful
Contrary to causing glaucoma, cataract surgery actually reduces IOP over the long term:
- Cataract surgery with IOL implantation results in a mean IOP reduction of 2.22 mmHg in glaucoma patients, with 59% achieving at least 3 mmHg reduction over a mean follow-up of 4.8 years. 3
- The average IOP decrease of 16.5% persists for at least 3 years postoperatively. 1, 4
- Recent systematic reviews of randomized controlled trials show consistent IOP reductions ranging from 4.1 to 8.5 mmHg after cataract surgery in open-angle glaucoma patients. 5
- Patients also experience a mean reduction of 0.2-1.0 glaucoma medications postoperatively. 5
Clinical Management Implications
For patients with controlled glaucoma on one or two medications, cataract surgery alone may be adequate for both visual rehabilitation and IOP control. 1, 4
Key management considerations include:
- Higher preoperative IOP predicts greater IOP reduction: Eyes with preoperative IOP ≥24 mmHg had mean IOP reduction of 4.03 mmHg, with 81% experiencing at least 3 mmHg reduction. 3
- Patients on fewer topical glaucoma medications preoperatively experience larger IOP reductions. 3
- Combined cataract-glaucoma surgery reduces the frequency and magnitude of early postoperative IOP spikes (only 14% had IOP rises ≥10 mmHg vs. 69% with cataract surgery alone). 2
Important Caveats
The sequence of surgeries matters for patients requiring both procedures:
- Performing cataract surgery after trabeculectomy increases the odds of filtration failure, with risk inversely proportional to the duration between procedures. 6
- Performing cataract extraction prior to glaucoma surgery has numerous benefits and should be considered when both procedures are needed. 6
- Combined surgery results in better IOP control at one year (mean difference -1.62 mmHg) compared with cataract surgery alone, though with uncertain effects on complication rates. 7
Appropriate postoperative care must include treatment of elevated IOP and corneal edema as potential complications. 1