A cataract occurs when the natural lens inside the eye, which is normally clear, becomes clouded or opaque, impairing vision. This clouding is caused by the breakdown and clumping of proteins within the lens, resulting in symptoms like blurred vision, faded colors, and increased glare. The primary objective of cataract surgery is to remove this clouded lens and restore clear vision by replacing it with a transparent, artificial lens. This procedure is one of the most frequently performed surgical interventions globally.
Phacoemulsification The Standard Procedure
Phacoemulsification, often simply called “Phaco,” is the most widely adopted technique for cataract removal in developed nations. This method is minimally invasive and relies on a small incision, typically ranging from 2.2 to 2.8 millimeters, made on the side of the cornea. The small size of this incision allows it to be self-sealing, reducing the need for sutures and promoting faster healing.
Once the surgeon accesses the lens, a specialized ultrasonic probe is inserted through the incision. This probe vibrates at high frequencies, generating ultrasound waves that break up or “emulsify” the cloudy lens nucleus into tiny fragments. These fragmented pieces are then suctioned out of the eye through the same probe. The combination of a small wound and efficient fragmentation leads to a rapid recovery and minimal trauma to the surrounding ocular tissues.
Manual Small Incision and Extracapsular Surgery
These techniques represent a different approach to cataract removal, where the lens is extracted without the use of an ultrasonic probe for fragmentation. Extracapsular Cataract Extraction (ECCE) involves making a larger incision, often between 9 and 12 millimeters, through which the lens nucleus is removed in a single or a few large pieces. This larger wound typically requires sutures for closure, leading to a longer recovery period and a higher risk of surgically induced astigmatism.
Manual Small Incision Cataract Surgery (MSICS) is an evolution of ECCE, utilizing a smaller incision, usually around 6 to 7 millimeters, created through a self-sealing scleral tunnel. The lens nucleus is still removed manually, often by a technique called “phaco-expression,” where the nucleus is gently pushed out of the eye. MSICS is particularly beneficial in areas where the high cost of phacoemulsification equipment is prohibitive, or for patients presenting with extremely dense cataracts that may be challenging to emulsify with ultrasound alone.
Laser-Assisted Cataract Surgery
Femtosecond Laser-Assisted Cataract Surgery (FLACS) introduces a high-precision laser to perform several preparatory steps that are traditionally executed manually. A femtosecond laser emits ultra-fast pulses of light to cut and separate tissue with micron-level accuracy. This technology is used to create the initial corneal incisions, which can be custom-designed for size and location.
The laser also performs a step called the anterior capsulotomy, creating a perfectly circular opening in the lens capsule, which is necessary to access the cataract. Additionally, the laser pre-softens and fragments the lens nucleus into smaller, manageable segments. By pre-fragmenting the cataract, FLACS aims to reduce the amount of ultrasonic energy required during the subsequent Phacoemulsification step, potentially leading to less stress on the eye and quicker recovery.
Selecting the Intraocular Lens
Regardless of the surgical technique used to remove the cloudy natural lens, the final step is the implantation of an artificial Intraocular Lens (IOL). This clear, synthetic lens replaces the focusing power of the natural lens and is selected before the surgery based on the patient’s visual goals.
Types of IOLs
The standard option is a Monofocal IOL, which is designed to provide clear vision at a single, fixed distance, typically far away. Patients with this lens will generally need reading glasses for near or intermediate tasks.
For those desiring a broader range of focus, Multifocal or Trifocal IOLs are available. These lenses use different focal points to allow for clear vision at near, intermediate, and far distances, reducing or eliminating the need for glasses. A specialized type, the Toric IOL, is designed with specific curvatures to correct pre-existing astigmatism, offering a tailored solution for patients with irregularly shaped corneas.