Astigmatism results from a misshapen cornea. People with astigmatism typically suffer from blurry or distorted vision, eye strain and headaches. They can also have difficulty seeing at night.
On Day 2 of the annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS 2022), Dr. B. Rubenstein, MD, Deutsch Family Professor and Chairman of the Department of Ophthalmology at Rush University Medical Center, Chicago, Illinois, dropped his top five tidbits of ophthalmological genius for dealing with the condition … and CAKE magazine was on hand to greedily gobble up every last crumb!
Crumb #1: Think Astigmatism!
It sounds simple, but Dr. Rubenstein says this is a common diagnostic error that can lead to the mismanagement of astigmatism during cataract surgery.
“You gotta think about it! Obviously, the first step is to decide if the patient needs cataract surgery. Is it visually significant? Does it interfere with their daily activities? Could there be a significant refractive advantage to cataract surgery? Once you’ve decided ‘yes, this patient needs cataract surgery,’ your first consideration should then be does this patient have treatable astigmatism? I consider this before doing any IOL calculations, is there astigmatism and do I need to correct it? Our goal is really to eliminate astigmatism (if possible), therefore less than a half a diopter is ideal to minimize a patient’s need for spectacles post surgery.”
Crumb #2: Accurate Pre-Op Assessment of Astigmatism
If we can’t accurately assess astigmatism, then we can’t properly treat it.
Dr. Rubenstein suggests the use of multiple assessment tools: “The more information, the better,” he said.
While biometry, corneal topography, manual keratometry and elevation mapping all have their merits, Dr. Rubenstein prefers biometry (and sometimes manual keratometry) for assessing axis and magnitude, and uses corneal topography as a qualitative guide.
“Preoperative corneal topography is essential for all cataract surgeries,” he continued. “It’s good for comparing axis and magnitude, assessing regular versus irregular astigmatism, and screening out patients with irregular mires. Don’t just look at the values on the biometry, because if their topography is showing something different, you know you can’t really trust those values.”
Crumb #3: Plan the Appropriate Surgical Technique
There are multiple techniques for correcting astigmatism, including manual PCRIs (peripheral corneal relaxing incisions), femto PCRIs, toric IOLs, or a combination of these.
“We don’t need to be married to one particular technique,” stressed Dr. Rubenstein.
Factors that could determine which treatment is best for a particular patient may include cost (some procedures are more expensive than others), as well as axis and magnitude of the astigmatism.
For most of us, a toric IOL is the first choice for treatment. These work best with regular, predictable astigmatisms, and can correct up to 4.75D.
Manual PCRIs have a lower cost and are good for correcting less severe astigmatism. They are also useful for treating mild non-orthogonal astigmatism.
Femto PCRIs are also useful for correcting small amounts of astigmatism, and can be used as an adjunct to toric IOL’s.
Crumb #4: Accurate Alignment
This can be achieved multiple ways: Manual, automated, or intraoperative.
The simplest way to do this is to anesthetize the eye and mark either the 6 o’clock, or 3 and 9 o’clock positions with the patient looking straight ahead and both eyes open.
Fancier techniques include Callisto Toric IOL Alignment, which overlays real time imagery with data from preoperative measurements.
Crumb #5: Precise Surgical Technique
It’s imperative that PCRIs are performed with the utmost precision. It’s important to make sure the epithelium is smooth, and the length and depth of incisions are exact.
“I think a lot of people give manual PCRIs a bad reputation because they are not performed with proper technique,” said Dr. Rubenstein.
Toric IOL’s also require proper technique.
Thus, a clean surgery, controlled corneal incisions, ensuring anterior and posterior capsule and zonules are intact, as well as precise lens alignment are crucial for a positive outcome.
Editor’s Note: ASCRS 2022 was held on April 22-26, as a physical show in Washington DC, USA. Reporting for this story took place during the event.