الفهرس 
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Abstract
The use of lasers in the treatment of cataract has long been desired by ophthalmologists to overcome risks of phacoemulsification. These risks include endothelial trauma and thermal burns at the wound due to heat generation.
Early attempts at the use of lasers involved Nd:YAG laser systems which are categorized into direct and indirect acting systems. The direct acting system (Photon laser PhacoLysis) consists of Nd:YAG system coupled with a conventional ultrasound phacoemulsification system.
The indirect acting system (Dodick photolysis), approved for cataract extraction by the FDA, transfers the laser energy in a Q-switched mode from the laser source to a laser probe. It produces no significant heat and allows for smaller wound sizes.
Er:YAG laser system has the advantages of lower energy requirements and lack of heat production. It works by being focused directly into the lens nucleus, and the subsequent optical breakdown causes micro fractures of the lens material. This laser is called the Phacolase MCL-29.
YAG laser systems have some limitations. They are restricted in their treatment of dense cataracts. Also phacoemulsification time with the laser tends to be longer than with ultrasound. The fibres used in Er:YAG laser systems have toxic properties upon degradation in an aqueous environment and, must be connected to a nontoxic tip. The fibre used in Nd:YAG systems is quartz, which minimally attenuates the energy, and must be replaced after every four to five surgeries.
Femtosecond laser is an infrared laser that works at wavelength of 1052 nm; it emits ultrashort laser pulses with a diameter of 0.001 mm, and use a shorter pulse time of 10-15 s. It improves safety, efficiency, precision and speed of ophthalmic surgeries.
Femtosecond lasers produce tissue interaction known as photodisruption. The laser cuts tissue by essentially vaporizing it. The tight focus of laser energy creates a plasma and then a cavitation bubble that expands and collapses separating the tissue.
Femtosecond laser cataract surgery companies are: Alcon, Inc. (Hünenberg, Switzerland), which purchased LenSx Lasers, Inc.; LensAR, Inc. (Winter Park, FL); OptiMedica Corp. (Santa Clara, CA), and Technolas Perfect Vision GmbH (Munich, Germany).
Use of the femtosecond laser has the potential to revolutionize cataract surgery with the creation of a capsulotomy, lens fragmentation, limbal relaxing incisions and clear corneal incisions. It has the potential advantages of improved safety and increased precisions.
The major risk involved in the surgery is loss of suction during the procedure and displacement of the laser pulses. The major disadvantage is the increased cost. Complex cataract cases, such as those with opaque nuclei, corneal opacity or edema, conjunctival bleb due to previous filtration surgery, or poor iris dilation, are contraindications for the procedure. Nevertheless, in the long run improved results will drive the acceptance (or rejection) of femtosecond laser cataract technology.