Even the most proficient
cataract and refractive surgeons can sometimes get less than satisfactory outcomes. As refractive cataract surgeons, we often enter the patient exam room expecting an enthusiastic answer such as “My vision is great. Everything is fantastic.” But occasionally, instead, the patient declares their vision is still blurry due to residual myopic or hyperopic refractive error.
Dr. Khandelwal offers these pearls for what post-operative action can be taken if you've missed that refractive target.
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Top four pearls for a missed refractive target
1. Check the refraction
Revisit the refraction and determine who performed it and if it was accurate. To ensure accuracy, repeat the process yourself. In addition, it is recommended to rule out pathologies in the patient that could influence the results, including macular edema, corneal edema, early posterior capsule opacification (PCO), or mild temporal edema at the site of the clear corneal incision.
Once these conditions are eliminated as culprits, complete a full evaluation using your usual refractive target checklist.
2. Review your original calculations
Like a Monday morning quarterback, review the procedure play-by-play. Reassess your original calculations and hone in on the reason that the refractive target was not hit.
Ask yourself questions such as:
- Did the eye have a narrow angle?
- Was the anterior chamber narrow and prone to deepening, leading to myopic error?
- Was there asymmetry between the eyes?
- Was it an exceptionally large eye?
- Did the eye have a scleral buckle from previous retinal disease (or other pathology)?
- Was there anything otherwise strange about the eye that might seem out of place?
Next, recheck the quality of the corneal measurements and axial length. Go back to the
pre-operative topography to see if you can see irregularities that could lead to hyperopic error. If there's no explanation, Dr. Khandelwal urges to repeat the calculations as well as the topography in both eyes. She offers the example of a patient whose mild anterior basement membrane dystrophy (ABMD) worsened, resulting in refractive error.
The problem may not lie in the intraocular lens (IOL), but in the need for further corneal intervention. Also, realize the role of ocular surface health, as it is more challenging to perform an accurate refraction on a
patient with ocular surface disease.
Tip: Establish whether it was a true refractive target miss or whether the eye was just exceedingly difficult to refract, due to an existing corneal pathology. This may determine whether you want to perform surgery on the second eye.
3. Determine how—and if—you will proceed with the second eye.
Prior pathology will be a key indicator; if AMBD was present in the first eye, decide whether the condition needs to be treated pre-operatively before an
IOL is implanted. The level of error will also be a determinant. If, post-operatively, the first eye has a residual hyperopia measuring +1 D to 1.5D, which is a considerable refractive error, you must resolve whether proceeding with the second eye is in the best interest of the patient.
When it is deemed advantageous to move to the second eye, Dr. Khandelwal, most commonly, prefers a 50% adjustment of the difference. Therefore, if the first eye was 1.0D myopic after surgery, for the second eye, you would take 0.5D of myopia and adjust accordingly when placing the IOL. Dr. Khandelwal noted that some sets of eyes are relatively unique and could require deviations from the 50% adjustment protocol.
Possible exceptions would be eyes with differing axial lengths or narrowness of the anterior chamber, one eye having a
prior corneal procedure, or other anatomical variations. If the two eyes are legitimately different, a 50% adjustment may not be an effective formula to follow, depending on the case presentation.
If at all possible, Dr. Khandelwal prefers to perform surgery on both eyes as patients do not often tolerate differences in brightness and anisometropia, even if that means performing a corneal refractive procedure on both eyes at a later date to achieve the desired vision. However, though not ideal, in some instances, the best decision might be to leave the patient anisometropic.
4. Maintain open communication with the patient
According to Dr. Khandelwal, one of the most common mistakes surgeons make is simply not communicating with the patient. By educating them on corneal measurements, axial length, and extenuating circumstances, you can
mentally prepare them by building appropriate patient expectations. Further, this reassures them that there are treatment options to possibly correct the existing complication and, hopefully, avoid any challenge in the second eye.
A sample conversation from Dr. Khandelwal:
“Your first eye didn't behave the way we wanted. We aimed for zero, but we ended up with plus one [+1.00D]. I am confident we can improve it the second time around, and I think you're gonna have a great outcome. We'll get you there. In light of this, we're going to make a slight adjustment with your other eye. Just know sometimes the eyes do behave differently than how the formulas predict.”
Final thoughts
Keep in mind, even with the utilization of the best technologies and devices; cataract surgery can still throw us a curveball similar to refractive corneal procedures, such as
laser-assisted in situ keratomileusis (LASIK), wherein the refractive target is frequently being hit 99% of the time.
With
IOL procedures, there can be outliers. But, by following the pearls laid out by Dr. Khandelwal, you can proceed with confidence in addressing that missed refractive target.
