Corneal burn during Phaco
-Corneal incision contracture (CIC), commonly referred to as wound burn, is a rare intraoperative complication of phacoemulsification.
-The phaco probe creates two sources of heat:
-Conversion of electrical energy to mechanical energy
-Friction heat when the phacoemulsification needle vibrates against the sleeve that contains the probe
-Water is usually used as a cooling agent to reduce the amount of thermal energy produced
-If the flow of irrigation fluid surrounding the phacoemulsification needle is disrupted, the generated heat may contact the tissue, with the corneoscleral wound site being most susceptible to damage
-Thermal damage to the collagen fibers in the sclerocorneal tunnel can occur once the temperature reaches 60 degrees Celsius, leading to a “phacoburn” over 1 to 3 seconds
-The wound burn results in the contracture of the incision site and surrounding tissue
INCIDENCE: Very low (0.037%)
RISK FACTORS:
-Level of ultrasound energy used during the phaco process, with higher levels or prolonged use
-Surgical approaches that rely more heavily on the use of ultrasound energy, such as divide-and-conquer, carousel, and stop-and-chop
-Decreased irrigation around the phaco tip
High viscosity OVDs such as Healon5 have been shown to significantly increase the risk of wound burn (exothermic nature of OVD)
-Surgical incision size, power modulation, and type of ultrasound used were not found to modulate the risk of corneal incision contracture
PREVENTION:
-Continuous irrigation of BSS on the outer surface of the phaco needle and aspiration through the central canal is critical to prevent the tip from increasing in temperature and causing subsequent thermal injury
-Verification of proper machine setup and adequate irrigation flow before insertion of phaco probe
-Frictional thermal generation can be reduced by avoiding long excursions, excessive manipulation, and angulation of the phaco handpiece, and ensuring that the site is an adequate size
-Irrigation and aspiration should be performed for up to 15 seconds at the beginning of the case if an OVD is being utilized. This ensures that the working space above the nucleus is free of the OVD, which protects against wound burn
DETECTION:
-Critical warning sign is the appearance of milky white fluid around the phaco tip
-Whitening of the cornea and gaping at the incision site
-At the end of the procedure, it can manifest as difficulty in maintaining watertight closure of the incision site
MANAGEMENT:
-Suturing the wound
-Soft BCL
- Very severe cases - patch grafts
COMPLICATIONS:
-Delayed wound healing
-Fistula formation
-Damage to corneal stroma and endothelium
-Inability to close the incision
-Increased surgically induced astigmatism
-Flat AC and iris prolapse, which may arise from persistent dehiscence due to the inability to achieve a watertight closure
Image from Rajan Eye Care Hospital
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