Over the years, many advances have taken place in the field of cataract surgery. The newest techniques have become so refined that cataract surgery is now considered a refractive procedure, with the goal of not only removing the cataract, but also decreasing the patient’s dependency on glasses.
- Topical Anesthesia for Cataract Surgery
- Clear Corneal Incision
- Premium Lenses
- Limbal Relaxing Incision
- ORA Intraoperative Aberrometer
- The Callisto Eye
- Educational Videos
A cataract is a lens that has become clouded. Many times, a patient will describe that looking through a cataract is like looking through a dirty window. During the cataract operation, a small ultrasound device is used to remove the clouded lens and a new, clear intraocular lens is inserted.
Measurements of the eye prior to surgery are used to select the power for the intraocular lens that will make the patients least dependent on glasses. At the San Jose Eye Institute, Dr. Yang uses the newest technologies available for cataract evaluation and surgery. Although ultrasound can be used to determine which intraocular lens power to use, the most accurate refractive results are obtained when using optical biometry, such as the IOL Master 700.
Dr. Yang also exclusively use the Signature Phacoemulsification System with the new WHITESTAR™ Technology. It is this machine that creates the ultrasound which breaks up the cataract into tiny pieces. The WHITESTAR™ upgrade reduces the total amount of energy used during the cataract extraction, resulting in a much quicker recovery time for the patient.
Topical Anesthesia for Cataract Surgery
The technique of using only eye drops to anesthetize the eye is a significant advance in cataract surgery compared to using a needle. With a needle injection, a long needle is inserted just underneath the eyeball and the anesthetic is then injected behind the eye. There is a risk for bruising of the eyelids, bleeding around the eyeball, droopy eyelids, and the patients are usually heavily sedated. With topical anesthesia, only eye drops are used to numb up the eye. There is no risk for bleeding and there is no chance that a needle could inadvertently penetrate the eye. Following cataract surgery, patients with a needle are required to have their eye patched until the next day, whereas those with topical anesthesia can go home without any eye patch. Dr. Yang routinely uses topical anesthesia in order to achieve the best results.
Clear Corneal Incision
There are many techniques used to enter the eye in order to remove the cataract. The size and location of the incision can affect the curvature of the cornea and potentially induce astigmatism. This can be minimized by having a smaller incision. Incisions in the sclera (the white part of the eye) are typically larger in length, whereas incisions in the clear part of the cornea tend to be very small. Dr. Yang typically uses a 2.4 mm incision in the cornea, resulting in an incision that does not require sutures to close.
Furthermore, unlike cutting in the sclera, there is no bleeding associated with making an incision in the cornea. As a result, without using a microscope, it is difficult to tell that surgery was even performed.
Premium Intraocular Lenses
Traditionally, a mono-focal lens is placed in the eye during cataract surgery. Following surgery with a mono-focal lens, the patient will typically need glasses to fine-tune the vision, allowing the patient to see far, intermediate and near. Lens technology has grown significantly, and today, there are many different lens options. Besides the standard mono-focal lens, there are now special Premium Lenses that offer unique features designed to help patients become less dependent on glasses.
Toric lenses are designed to eliminate or significantly decrease the amount of astigmatism, or warping of the cornea surface. The amount of astigmatism reduced is extremely accurate and stable. By using a toric lens, the vision without glasses is improved because the distortion from astigmatism is improved. Toric lenses can remove upwards of 4 diopters of astigmatism. Ask Dr. Yang about the Alcon AcrySof IQ Toric IOL and the Tecnis Toric IOL.
Multi-focal lenses allow images at different distances to be seen in focus. Working distances can be broken down into far (driving, TV), intermediate (cell phones, computers), and near (reading). Multi-focal lenses can bring two working distances in focus: either far and intermediate, or far and near, depending on the patient’s desire. Multi-focal lenses include the ReSTOR Multifocal lens and the Tecnis Multifocal lens. The ReSTOR Multifocal also comes in a toric version to help patients who also have astigmatism.
Accommodating lenses dynamically change their shape inside the eye to allow patients to see far, intermediate and near. The Crystalens is the first accommodating lens approved by the FDA. In 2013, Trulign was introduced, which is essentially a combination of the Crystalens with a toric lens to correct for astigmatism as well.
Extended Range of Vision lenses are the latest category of premium lenses that allow patients to see far, intermediate and near. In contrast to multi-focal lenses, which allow patients to see two distances in focus, these lenses allow patients to see a continuous range of distances in focus. The Symfony lens is the first lens in this category, approved by the FDA in 2016. The Symfony Toric lens is the Symfony lens combined with a toric lens.
Dr. Yang offers all of the above premium lenses, giving patients the greatest flexibility in customizing the lens choices that are best-suited to the patients’ lifestyle and visual demands.
Limbal Relaxing Incision
This is a technique similar to astigmatic keratotomy which can be used to decrease the amount of corneal astigmatism. A corneal topography is used prior to cataract surgery to map the extent and location of the astigmatism. Based on this map an incision is made on the cornea to decrease the amount of astigmatism. The effect of the incision is dependent on the patient’s ability to heal, and so the effect is somewhat variable. Reducing the astigmatism at the time of the surgery will further reduce the patient’s dependence on glasses.
ORA Intraoperative Aberrometer
This latest technology is used at the time of cataract surgery to improve the refractive outcome following cataract surgery. Traditionally, the power of the new intraocular lens is determined prior to surgery by measuring the curvature of the corneal surface and length of the eye. Because of the presence of the cataract, certain assumptions also have to be made, and the desired lens power is calculated.
With ORA, some of these assumptions can be eliminated. At the time of surgery, after the cataract is removed, ORA can be used to measure the true refractive power of the eye. Real-time calculations are then made to determine the best-fit lens power. The result is a truly customized lens power calculation for each individual patient, resulting in improved uncorrected vision. Dr. Yang is pleased to be one of the first in the San Jose area to be able to offer this technology to all of his cataract surgery patients.
The CALLISTO Eye
This is computer-assisted technology that allows the operating microscope to project clinical information on to the eye, and track the eye dynamically during cataract surgery, eliminating errors introduced by eye movement and rotation. This system has many applications, but there are two clinical situations that are particularly useful:
1. For patients who have astigmatism, and wish to have it reduced during cataract surgery, knowing the axis of the astigmatism is critical. The CALLISTO Eye system will project an image of the astigmatism axis on to the eye during surgery. When the surgeon looks through the microscope, the superimposed axis will rotate to compensate if the eye rotates.
2. Certain intraocular lenses are more sensitive and require centration with the visual axis. Unfortunately, the center of the visual axis does not necessarily correlate with the center of the eye or pupil. Before surgery, when the pre-op measurements are taken, the patient can fixate on an image, and CALLISTO Eye can determine the true visual center. This center is seen in the microscope, superimposed on the eye, and the new intraocular lens can be confidently centered.
This technology requires a significant equipment upgrade at the surgery center as well as the surgeon’s office, and Dr. Yang is pleased to be one of the few in the Bay Area to be able to offer this technology to his patients.
Accommodating Intraocular Lenses
Crystalens / Trulign
Extended Range of Vision Intraocular Lenses
Symfony / Symfony Toric