Intra-Ocular lens implants
Technological advancements in Ophthalmology continue to amaze me even after 25 years of practice. In the past few years there has been an explosion in new intraocular lenses (IOL) available. These allow patients to experience better vision and more eyeglass independence.
A cataract is a clouding of the natural occurring focusing lens of the eye. In order to remove the cloudiness the entire lens must be removed. Therefore a method to replace the focusing ability of the eye is required. The most common method is the IOL. In the past, the only style available was one that corrected the major focusing power. It could not correct astigmatism, reading vision or other optical aberrations of the eye. We now have IOLs that can do all of these things. However, it is still not possible to do all of them at once. We expect an IOL available within the next year or so that will be able to correct all three of these errors.
Astigmatism is a focusing error in the eye that traditionally has been corrected with glasses or contact lenses. It is a condition where instead of the eye being round like a basketball it is oblong like a football. This creates two axes of focus and requires a special toric lens to correct it. As mentioned earlier there is now an IOL with toric surfaces to correct astigmatism. When a patient receives this IOL they usually do not require glasses for distance vision.
As everyone over forty knows, at this stage in life typically one begins to need reading glasses. There are currently several choices available to obtain useful reading vision without glasses following cataract surgery. The method familiar to many contact lens patients called Monovision corrects one eye for distance and one eye for near. Many people have been using this method successfully prior to cataract surgery and are good candidates to do it with IOLs. The only difference is that it is permanent with IOLs unless further surgery is performed. A variation on this method involves correcting the eye with near vision for intermediate vision instead. We have found that this is better tolerated by most people. It does not create as much of a disparity between the two eyes and allows better depth perception than full Monovision. These patients might not be able to go fulltime without glasses. They may need to wear them to drive at night and for prolonged reading. However, in our digital society they can usually see their cell phones and computers and function approximately 75-80% of the time without glasses.
Another method to correct reading vision is multifocal IOLs. These implants allow distance, intermediate and reading vision in each eye. They work by creating multiple zones of vision. Another method is the accommodating IOL. It works buy purportedly changing shape with focusing effort. As mentioned earlier neither of these IOLs are available with astigmatism correction. Nevertheless, the multifocal IOL with a toric surface is in FDA studies and may be available within a year.
In addition to the focusing problems I have already discussed there are more aberrations inherent in every optical system. They are less significant but even so can degrade image quality. None of the so-called Higher Order Aberrations have previously been correctable with glasses, contact lenses or IOLs. Recently aspheric IOLs have become available, which can correct the next most significant aberration, called spherical aberration. Without getting into an overly boring and technical discussion of optics these IOLs can provide better image quality and enhance vision.
At Eye Specialists of Mid-Florida we are offering all of these IOL choices to our patients in an effort to provide them with the best vision possible after cataract surgery, as well as the lifestyle convenience of less dependence on glasses or contact lenses.
In order to determine which IOL is appropriate for each patient we use advanced equipment to perform individual measurements and do a thorough history and physical exam including a lifestyle questionnaire. We have been impressed with the results these new IOLs provide and look forward to advancing our practice as technology continues to improve.
story by DAVID M. LOEWY, MD
BIO: David M. Loewy, MD is an ophthalmologist specializing in cataract and laser surgery at Eye Specialists of Mid-Florida and is a PCMA member. Dr. Loewy currently resides in Winter Haven with his wife Debbie.