FEB 26, 2015
Cataract/Anterior Segment
This study found that femtosecond pretreatment before cataract surgery caused a greater transient rise in IOP after treatment and a higher residual IOP after vacuum undocking in glaucomatous versus nonglaucomatous eyes. While this is well-tolerated in the short term, the authors say the long-term implications for eyes with glaucoma are unknown.
Subjects were 97 patients undergoing femtosecond laser pretreatment using a fluid-filled optical docking system (Liquid Optics Interface). Forty-three eyes (30.1%) had primary open-angle glaucoma (POAG). The researchers measured IOP with the patient supine at four time points using a rebound tonometer (Icare Pro).
In patients with and without glaucoma, IOP increased from baseline after the vacuum was applied, as found previously. This was followed by a further increase in IOP levels after completion of the femtosecond laser treatment (capsulotomy and lens fragmentation), with the mean post-treatment IOP values significantly higher in glaucomatous vs. nonglaucomatous eyes. After undocking of the vacuum, IOP levels decreased in both groups but remained above preoperative values and were higher in eyes with glaucoma.
The authors speculate that this can be attributed to production of plasma in the anterior chamber, a byproduct of femtosecond laser pretreatment that generates expansile cavitation bubbles with a consequent increase in IOP. A forward shift in the lens-iris diaphragm with secondary angle narrowing is also a potential contributing factor.
They say it is unknown whether the transient IOP changes during treatment and residual rise in IOP measured two minutes after undocking will worsen glaucoma in glaucomatous eyes in the long term.