Does laser peripheral iridotomy (LPI) mprove the safety of cataract surgery and patients with narrow angle?

A narrow angle on Slit lamp microscopic examination and confirmed either by gonioscopy, Pentacam imaging, and/or UBM, is important to assess in all phakic patients (ie, the patient’s natural lens is still present), particularly before cataract surgery. 

Laser peripheral iridotomy (LPI) is a safe procedure that If performed prior to cataract surgery can improve the safety of cataract surgery in patients with narrow angles. 

Here are several key reasons:

1. Increased Anterior Chamber Depth (ACD): LPI helps increase the ACD, which helps make cataract surgery safer. A deeper anterior chamber provides the surgeon with more space to operate, reducing the risk of damaging the cornea's endothelial cells during the procedure (see reference below). Opening the angle with LPI prior to cataract surgery also helps the surgeon better choose the correct intraocular lens power. Studies seemed to indicate that the effective lens position changes more dramatically, in patient's with shorter eyes, and that LPI might help prevent this. This is an area where future research is needed. For instance, it may be better in patients with shorter eyes to choose a light adjustable lens to avoid small refractive surprises. Future studies are needed to confirm the benefits of LAL implants and narrow angle patients.

2. Reduced Endothelial Cell Loss: Studies have shown that eyes with shallow ACDs are more susceptible to endothelial cell loss during cataract surgery. By increasing the ACD through LPI, the risk of this complication is reduced

3. Lower Risk of Intraoperative Complications: A shallow anterior chamber is associated with a higher risk of surgical complications such as posterior capsule rupture, iris prolapse, and corneal edema. Increasing the ACD through LPI reduces these risks, making the surgery safer  

4. Better Surgical Outcomes: By addressing the narrow angle condition before cataract surgery, LPI can lead to better overall surgical outcomes and lower the likelihood of postoperative complications 

Overall, performing LPI in patients with narrow angles before cataract surgery can significantly enhance the safety and effectiveness of the procedure, ensuring better patient outcomes.

References:

1.

ARVO Annual Meeting Abstract  |   April 2009

Shallow Anterior Chamber Depth Is Associated With Increased Surgical Complications During Cataract Surgery

L. A. Anderson; A. Gupta; N. Srikantha; S. Goverdhan; J. Kirwan

 Author Affiliations & Notes

Investigative Ophthalmology & Visual Science April 2009, Vol.50, 5578. doi:

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Abstract

Purpose: : To assess if smaller anterior chamber depth (ACD) is a risk factor for intra-operative complications during cataract surgery.

Methods: : Data from an electronic cataract database was analysed for 8891 eyes at the Queen Alexandra Hospital, Portsmouth, UK. All eyes which had a central ACD measured were included in the study. All intra-operative complications and issues (posterior capsule rupture/dialysis, capsulorexis tears, iris prolapse, corneal oedema and descemet tears) were recorded. Complication rates were compared between ≤ 2.5mm and > 2.5mm ACD groups. Chi square (2- tailed with Yates correction) were used to calculate P values and odds ratios (OR) with 95% confidence intervals.

Results: : 1138 eyes were identified as having an ACD ≤ 2.5 mm and 7753 had an ACD >2.5 mm. The overall complication rate was 3.56%. Complications were seen significantly more in the ACD ≤2.5 mm group as compared to the ACD >2.5 mm group, 54(4.75%) versus 263(3.40%) with an odds ratio of 1.42 (P=0.026, 95% CI = 1.05 -1.92). Posterior capsule rupture/zonular dialysis (+/- vitreous loss) was seen in 23 (2.0%) of the eyes with an ACD ≤ 2.5 mm compared to 95 (1.2%) in the > 2.5 mm ACD group (OR= 2.060, P=0.036, 95% CI = 1.64 -2.60) with an over 2 fold risk. A shallow anterior chamber with vitreous bulge was also significantly more common in the ≤ 2.5mm ACD group i.e., 51 (4.48%) versus 93 (1.2%) in the >2.5 mm group (OR= 3.386, P<0.0001, 95%CI = 2.70-5.50).

Conclusions: : Patients with anterior chamber depths ≤ 2.5mm are significantly more at risk of developing complications during cataract surgery. ACD should be considered as a factor in risk stratification preoperatively.

2. https://www.reviewofophthalmology.com/article/cataract-surgery-in-eyes-with-angle-closure)