Introduction
Femtosecond laser (FSL) cataract surgery is still beginning, although it is gaining favor due to better uniformity and predictability for corneal incisions and anterior capsulorhexis. It thus allows for less phacoemulsification energy and time to be used, which results in less corneal edema. Furthermore, the FSL enables greater anterior capsulotomy circularity, capsule overlap, intraocular lens (IOL) insertion, and IOL centration. In the near term, these benefits have improved visual and refractive results. Complication rates are modest and continue to decrease with surgeon expertise.
What Is a Laser, and the Function of a Femtosecond Laser?
A laser uses stimulated emission to emit electromagnetic light. Ophthalmic lasers have a defined wavelength, pulse pattern, energy, duration, repetition rate, and spot size. This allows photons from the coherent, monochromatic laser beam to arrive at the target tissue at the same time and place. The femtosecond (FS) laser has a wavelength of 1053 nm and is an infrared laser. Like Nd: YAG lasers, FS lasers function by photo disrupting or photoionizing optically transparent tissue, such as the cornea.
Ophthalmology has always been at the forefront of the usage of lasers (Light Amplification by Stimulated Emission of Radiation), with a wide range of lasers being used for more than 50 years. Dr. Gerhard Meyer-Schwickerath, a German ophthalmologist, proposed laser photocoagulation of the retina in 1949. As a result, by adjusting these parameters, they may be absorbed in different tissues at different depths, with diverse biological consequences.
As a result, lasers may now target any problem within the eye. Many lasers employ molecular vibration to produce localized heat effects such as photocoagulation (e.g., argon laser), which induces protein denaturation. Other lasers, such as the excimer laser used in refractive surgery and the neodymium: yttrium-aluminum-garnet (Nd: YAG) laser, work through photoablation or photo disruption.
What Is Femtosecond Cataract Surgery?
The femtosecond laser (FSL) originally debuted as a microkeratome in corneal refractive surgery to generate the corneal flap. Following that, the indication was broadened to include all forms of corneal surgery, including lamellar and penetrating keratoplasty, ring-segment implantation in keratoconus, and developing presbyopia inlay pockets. The early corneal FSLs used a frequency of 30 kilohertz (kHz). The repetition rate was later doubled to 60 kHz, and the most recent 160 kHz FSLs can form a corneal flap in 10 seconds. Higher repetition rates require less energy to provide the same tissue impact. The pulse duration of FSLs employed in cataract surgery is 400-800 femtoseconds (fs), and the energy range is in microjoules (J, 106 J).
Cataract surgery is the most frequent ocular operation performed worldwide. Cataract surgery has evolved from a vision restoration operation to a refractive procedure. Ophthalmic surgeons restore optical media purity and alter the eye's refractive power.
Furthermore, presbyopia can be treated using multifocal intraocular lenses (IOLs)]. Because corneal laser refractive surgery is more accurate than cataract surgery, considerably more effort is needed to enhance refractive results. Patient expectations have grown, and doctors must be skilled at interacting with patients to manage them appropriately. FSLs provide new possibilities for both patients and doctors.
What Are the Indications and Advantages of Femtosecond Cataract Surgery?
The following are the primary indications for FSL during cataract surgery:
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Making an anterior capsulotomy
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Laser liquefaction and fragmentation of hard and soft lenses, respectively
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Corneal incisions on a single plane or many planes
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Controlling pre-operative corneal astigmatism using arcuate corneal incisions
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With the LenSx system, the diameter of the anterior capsulotomy may be adjusted between 4.5 and 6 mm.
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A hybrid pattern may be utilized for lens fragmentation. The center 3.0 mm core is liquefied, and the periphery lens is fragmented into 4 to 8 slices (cross pattern and cake or pizza pattern).
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This approach removes the core lens, allowing access to the remaining lens peripheral.
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As a result, the ultrasonic phacoemulsification energy and duration are reduced, resulting in improved one-day post-operative visual acuity and decreased corneal and cystoid macular edema (CMO).
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Other benefits include less manipulation within the eye due to the pre-fragmented and liquefied lens.
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Most research only used the FSL up to grade 4 on the nuclear scale of the Lens Opacities Classification System (LOCS).
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Because the water content of the lens is low in advanced brunescent cataracts, the laser absorbs less energy. Because the water concentration in white tumescent cataracts is substantial, efficient lens fragmentation is improbable.
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The FSL is confined to the anterior capsulotomy and corneal incisions.
What Are the Contraindications of Femtosecond Cataract Surgery?
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Scarring of the cornea.
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Relative contraindication: mature cataract.
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Relative contraindication: small, non-dilating pupil.
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The presence of a tiny, non-dilating pupil smaller than 6 mm in diameter is a relative contraindication to FSL cataract surgery (lens fragmentation).
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An anterior capsulotomy can be performed with a 5.0 mm pupil, although there is a considerable risk of iris damage.
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In such circumstances, malyugin rings or iris hooks may be utilized. Corneal incisions can still be made in cases when the pupils are tiny.
Can Femtosecond Lasers Make Cataract Surgery More Effective?
Most cataract surgeons reach the anterior chamber by a precise corneal incision (CCI) despite this procedure being linked to an increased risk of postoperative endophthalmitis. A new study used anterior segment OCT after cataract surgery to reveal that most eyes had an internally gaping corneal hole and Descemet's membrane separation following CCI.
Several investigations have corroborated this conclusion, and it is hypothesized that these wound anomalies are one factor that raises the incidence of postoperative endophthalmitis. FSLs have been examined for usage in corneal incisions because the laser may allow for more square construction, which has proved to be more leakage-resistant. Despite not being a traditional reason for cataract surgery, these FSL
Conclusion
FSLs have the potential to change the way cataract surgery is performed in the future years. Already, the procedure has demonstrated excellent results for precise and self-sealing corneal incision, highly circular, robust, and accurate capsulorhexis, and safer and less technically challenging phaco-fragmentation and subsequent phacoemulsification. The FSL is used mainly for corneal incisions, anterior capsulotomy, and lens fragmentation. Aside from enhanced precision and accuracy, the following energy and time requirements for phacoemulsification are significantly reduced. The FSL is not widely used, presumably because of the added expense with modest benefits over an existing successful treatment. New advances, such as phacoemulsification tips and smaller incision alternatives, are predicted. Combined FSL and phacoemulsification devices that treat the lens and the cornea simultaneously are expected.
