Outcomes of High vs Physiological Intraocular Pressure During Cataract Surgery Using ACTIVE SENTRY

Cataract surgery is a widely performed procedure across the world that helps restore vision in many patients suffering from cataracts. The surgery has known many improvements across time and continues to do so. Irrigation is an essential component of the surgery. Fluid is constantly being circulated to help regulate temperature as heat is generated with the use of ultrasound energy, to minimize tissue trauma, and to create an intraocular pressure sufficient to keep the anterior chamber stable. In parallel, aspiration brings the components of the cataract closer to the surgical instrument. A balance between irrigation and aspiration during surgery is essential to maintain stability in the anterior chamber. However, an ideal flow rate, which influences intraocular pressure (IOP) during surgery, is yet to be determined. Most recent studies with Centurion Active Sentry (maintaining vacuum and aspiration rates the same) show that there is similar efficiency between higher and lower IOP settings. Traditionally, high-flow rates have been used in advanced cataracts and are believed to increase the space in the anterior chamber. However, they are known to create fluid turbulence and are associated with risks of tissue damage, including cell loss in the endothelial layer of the cornea. High intra-ocular pressure during surgery has also been shown to cause damage to the optic nerve as well as to the retina. Distorting and stretching the anterior chamber during phacoemulsification have also been associated with increased pain experienced by the patient. Comfort can be achieved by lowering pressure levels. Low-flow rates have a better safety profile, reduce IOP and pressure fluctuations while offering equal efficiency, including comparable surgical time. Using central corneal thickness (CCT) as an indicator of corneal trauma, it has been shown that patients that have had surgery with low-flow rates present no change in the CCT postoperatively while patients in the high-flow rates show signs of corneal damage as well as greater anterior segment inflammation. As less fluid turbulence is created with low-flow rates, there is decreased risk of fragment contact with the cornea's inner surface, thus reducing cell loss. Alcon Laboratories, Inc. developed Active Fluidics which allows to stabilize intraocular pressure and prevent IOP fluctuations as well as IOP surges during surgery. It is now further equipped with the Active Sentry handpiece which is integrated to the surgical instrument and acts as a sensor to pressure variation. It allows rapid feedback to maintain a stable anterior chamber. Our research project aims to assess the outcomes following phacoemulsification done with physiological IOP with the help of the Active Sentry handpiece compared to traditional high IOP levels.

Inclusion criteria

• No prior ocular surgery including corneal refractive surgery
• Bilateral visually significant cataract, similar in density (LOCS III grade 2+), undergoing uncomplicated cataract surgery
• Equal dilated pupil size ≥6mm, no use of pupil expansion devices
• Axial length 21-26mm, refractive error between -8.00D to +6.00D and cylinder ≤ 4.50D, normal K values <48.00D
• Normal CCT range 540µm ± 50

Exclusion criteria

• History of corneal disease or dystrophies
• Media opacification for reasons other than cataract
• Compromised zonular integrity or stability.
• Retinal and retinal vascular pathologies, age-related macular degeneration
• Glaucoma
• Patients with uncontrolled systematic diseases, including hypertension, diabetes, systemic cardiovascular diseases, and hematological diseases.