Nearly 70% of corneas have 0.75 D or more of preoperative corneal astigmatism — enough to affect their vision meaningfully. Performing cataract surgery alone actually worsens the astigmatic state of most of our patients.
After cataract surgery, most patients expect to have improved vision. However, when they still need to use prescription lenses to see clearly post-surgery, the disappointment they feel can be significant.
This is particularly the case when the cause is uncorrected astigmatism. There are a lot of patients who don’t realize that they have a little bit of astigmatism. Or, perhaps they have some astigmatism, but their corneal astigmatism is balanced by their lenticular astigmatism.
In these cases, cataract surgery that doesn’t include correction of astigmatism can lead to even blurrier vision and/or a continuing need for prescription lenses after surgery. Then, the patient is sitting in the chair upset with the surgeon, asking ‘Why am I not seeing 20/20?’”
With a multifocal lens, residual astigmatism is especially bothersome. Multifocal lenses reduce contrast to a degree that does not bother the vast majority of patients, unless there are other comorbidities that reduce contrast.
Of these comorbidities — such as optic nerve disease, macular pathology and dry eye — astigmatism is the easiest to address with a simple, simultaneous procedure or toric lens to greatly reduce or eliminate it.
Development of future disease years after cataract surgery can degrade vision, so correcting astigmatism now only improves patients’ long-term outlook.
The Option of Astigmatism Correction
Research has shown that 72 percent of cataract patients have more than 0.5 D of astigmatism. However, only 7 percent of all IOL procedures use toric IOLs. One common reason patients aren’t having their astigmatism corrected is cost, particularly since it isn’t typically covered by insurance.
Doctors should always give the patient the option of astigmatism correction and then let the patient decide. It’s important for patients to understand that opting to have a monofocal lens implanted could result in them paying just as much for prescription lenses over time as they would have for the toric lens.
Other reasons astigmatism goes uncorrected include surgeons’ lack of confidence in their ability to perform the procedure and/or their lack of access to the devices required to implant toric lenses— such as corneal topographers.
Additionally, some patients don’t understand how their astigmatism will affect their vision after surgery. Others are simply used to wearing prescription glasses and don’t mind continuing to do so after surgery.
With a variety of toric lenses on the market, it can be challenging to determine which to select and when to use them. The question of when a toric lens should be used to correct astigmatism is often related to the question of how early this solution can or should be used.
For example, if a toric lens that— at its lowest—corrects only 1.2 D, using it with a patient who has 0.5 D against the rule can make the astigmatism worse. Instead of 0.5 D, the patient would now have 0.75 astigmatism.
Astigmatism as little as 0.5 D has the potential to adversely impact functional and low-contrast acuity. Treating astigmatism in its earliest stages can have a measurable impact on patients’ ocular comfort and visual performance.
There’s a huge opportunity for both patients and physicians to benefit from correcting astigmatism during cataract surgery. Patients will be more satisfied because they’ll see better without glasses. It’s rewarding to have these super happy patients in the clinic.