Basics of Macular Degeneration
by Bear Eye Care
Blog
What Is Intraoperative Aberrometry?
Yes, that is a mouthful, but the concept isn’t quite as hard as the name.
An Intraoperative Aberrometer is an instrument we can use in the operating room to help us determine the correct power of the implant we put in your eye during cataract surgery.
Cataract surgery is the removal of the cloudy natural lens of your eye and the insertion of a new artificial lens inside your eye called an intraocular lens (IOL).
The cloudy cataract that we are removing has focusing power (think of a lens in a camera) and when that lens is removed, we need to insert an artificial lens in its place to replace that focusing power. The amount of focusing power the new IOL needs has to match the shape and curvature of your eye.
To determine what power of lens we select to put in your eye, we need to measure the shape and curvature of your eye prior to surgery. Once we get those measurements, we can plug those numbers into several different formulas to try and get the most accurate prediction of what power lens you need.
Overall, those measurements and formulas are very good at accurately predicting what power lens you should have. There are, however, several eye types where those measurements and formulas are less accurate at predicting the proper power of the replacement lens.
Long Eyes: People who are very nearsighted usually have eyes that are much longer than average. This adds some difficulty with the accuracy of both the measurements and the formulas. There are special formulas for long eyes but even those are less accurate than formulas for normal length eyes.
Short Eyes: People who are significantly farsighted tend to have shorter-than-normal eyes. Basically, the same issues hold true for them as the ones for longer eyes noted above.
Eyes with previous refractive surgery (LASIK, PRK, RK): These surgeries all change the normal shape of the cornea. This makes the formulas we use on eyes that have had previous surgery not work as well when the normal shape of the cornea has been altered.
This is where intraoperative aberrometry comes in. The machine takes the measurements that we do before surgery and then remeasures the eye while you are on the operating room table after the cataract is removed and before the new implant is placed inside the eye. It then presents the surgeon with the power of the implant that the aberrometer thinks is the correct one. Unfortunately, the power that the aberrometer selects isn’t always exactly right, but with the combination of the pre-surgery measurements and the intra-surgery measurements the overall accuracy is significantly enhanced.
The intraoperative aberrometry is also very helpful in choosing the power of specialty lenses like multi-focal and toric lenses.
We would encourage you to consider adding intraoperative aberrometry to your cataract surgery procedure if you have either a long or short eye (usually manifested as a high prescription in your glasses) or if you have had any previous refractive surgery.
Article contributed by Dr. Brian Wnorowski, M.D.
A wrinkle on the retina -- which is also known as an epiretinal membrane (ERM) or a macular pucker -- is a thin, translucent tissue that develops on the surface of the retina.
The retina is the inner layer that lines the inside of the back of the eye and is responsible for converting the light image into an electrical impulse that is then transmitted to the brain. An epiretinal membrane that forms on the retina goes unnoticed by the patient many times, and is only noticed during a dilated eye exam by an eye doctor.
Epiretinal membranes can become problematic if they are overlying the macula, which is the part of the retina that is used for sharp central vision. When they become problematic they can cause distortion of your vision, causing objects that are normally straight to look wavy or crooked.
Causes of a wrinkle on the retina
The most common cause is age-related due to a posterior vitreous detachment, which is the separation of the vitreous gel from the retina. The vitreous gel is what gives the eye its shape, and it occupies the space between the lens and the retina. When the vitreous gel separates from the retina, this can release cells onto the retina's surface, which can grow and form a membrane on the macula, leading to an epiretinal membrane.
ERMs can also be associated with prior retinal tears or detachments, prior eye trauma, or eye inflammation. These processes can also release cells onto the retina, causing a membrane to form.
Risk factors
Risk for ERMs increases with age, and males and females are equally affected.
Both eyes have ERMs in 10-20% of cases.
Diagnostic testing
Most ERMs can be detected on a routine dilated eye exam.
An optical coherence tomography (OCT) is a noninvasive test that takes a picture of the back of the eye. It can detect and monitor the progression of the ERM over time.
Treatment and prognosis
Since most ERMs are asymptomatic, no treatment is necessary. However, if there is significant visual distortion from the ERM or significant progression of the membrane over time, then surgical intervention is recommended. There are no eye drops, medications, or nutritional supplements to treat or reverse an ERM.
The surgery is called a vitrectomy with membrane peeling. The vitrectomy removes the vitreous gel and replaces it with a saline solution. The epiretinal membrane is then peeled off the surface of the retina with forceps.
Surgery has a good success rate and patients in general have less distortion after surgery.
Article contributed by Dr. Jane Pan
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