Fluid Supplementation Through Weakened Zonules via Side-Port Incision to Maintain Intraocular Pressure in High Myopic...

During phacoemulsification, the infusion pressure can cause the liquefied vitreous fluid to escape through the ciliary fiber interspace in highly myopic eyes, leading to reduced vitreous cavity pressure similar to vitrectomized eyes. This study assessed the probability of low intraocular pressure (IOP) in high myopic eyes with different axial length (AL) group undergoing cataract surgery, as well as the impact of balanced salt solution (BSS) supplementation and the optimal IOP value for such supplementation.

The control group consisted of cataract eyes with normal AL (group 1: 22 mm ≤ AL < 24.5 mm), while cataract eyes with high axial myopia were categorized into three groups (group 2: 26 mm ≤ AL < 28 mm, group 3: 28 mm ≤ AL < 30 mm, group 4: AL ≥ 30 mm). IOP was measured using the iCare pro tonometer intraoperatively. BSS supplementation was performed to raise IOP in cases of low IOP, before intraocular lens (IOL) implantation and before the end of surgery. The probability of low IOP was calculated, and the IOP before and after supplementation were compared.

Ninety-five eyes were included. The total probability of low IOP in groups 2, 3, and 4 was 56.52, 62.50, and 70.83%, respectively, significantly higher than that in group 1 (16.67%). Similarly, the probability of low IOP before IOL implantation was significantly higher in groups 2, 3, 4 (43.48, 41.67, and 62.50%) compared to group 1 (4.17%, P < 0.05). The IOP before and after the first BSS supplementation in three high myopia groups were statistically significant (P < 0.05), increasing from 12.10 mmHg (range, 6.0-24.9 mmHg) to 16.60 mmHg (range, 10.2-34.4 mmHg). After the second BSS supplementation before the end of surgery, the IOP of high myopia groups increased from 12.60 mmHg (range, 7.0-25.3 mmHg) to 14.60 mmHg (range, 9.8-25.3 mmHg).

The condition of highly myopic eyes seems more likely to develop low IOP during cataract surgery. There is an observed correlation: as AL increases, the total probability of low IOP rises. In patients with IOP < 9.5 mmHg intraoperatively, fluid supplementation via a side-port incision can effectively raise IOP to about 16 mmHg before IOL implantation and about 14 mmHg after incision sealing, facilitating smoother IOL implantation and reducing the risk of postoperative low IOP.

NCT, NCT05201677. Registered 23 November 2021-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05201677 .