It’s no secret that the scars and shape of the cornea after radial keratometry (RK) have made both cataract surgery and IOL selection for these patients a challenge. It is hard to measure the visual center of the cornea, and we often find highly irregular corneas. This results in an increase in higher-order aberrations, which basically creates a multifocal cornea. This can hurt us but can also help us later, as these patients tend to have a good level of extended range of vision. So, if we can hit the refractive target closely, we can achieve good results for our patients.
Here, I present two cases in which the Barrett True K formula and the Light Adjustable Lens (RX Sight) resulted in positive patient outcomes.
CASE 1: Begging for a Solution
A 60-year-old woman presented for a cataract evaluation. The patient told me she was desperate to see. Glasses didn’t work, and she was unable to wear contact lenses. She could not drive easily and only rarely would drive at night, not being able to see street signs or feel safe when driving. Her corrected vision was OD: 20/40-2 with +7.25 -2.75 X 120 OS: 20/40-1 with +8.00 -6.00 X 120.
Her history was positive for unsuccessful RK surgery in Tijuana, Mexico years prior. Specifically, she underwent multiple RK surgeries resulting in a 20 cut RK OD, and a 22 cut RK with her arcuate keratotomy penetrating the radial incisions inferior temporally OS. (See Figure 1A, Figure 1B, respectively.) Corneal topography showed highly irregular mires, especially OS. (See Figure 2 and Figure 3).
Scleral Incisions were used in hopes of preventing the RK incisions from opening.
Using the Barrett True K formula, her axial length was 26.15 in each eye, and K’s ranged from high 20’s to mid 30’s. The Barrett True K formula suggested a 25 D and 24 D Light Adjustable Lens (LAL) (RxSight) in OD and OS, respectively.
Post LAL Pre-treatment Rx:
OD: +4.25 -7.25 x 096
OS: +7.25 -12.00 x 123
I waited 7 weeks for the patient’s RK incisions to stabilize before starting treatment. (The corneal integrity creating stable refractions is always suspect in RK patients, so do not be afraid to wait for stabilization of the incisions.)
Post 3 Treatments:
Va sc 20/25 OD and 20/100 OS
OD +1.00 -1.00 x 105 20/20
OS +2.00 -6.00 x 120 20/30 -2
Today, this patient is driving without any refractive correction and wearing no glasses for distance. Additionally, he reads J3 without correction.
Case 2: Hyper Hyperopia
A 62-year-old patient with a history of S/P 10 cut RK OD and 14 cut RK OS, along with AKs for astigmatism, S/P LASIK OU, dry eye disease (DED), and irregular corneas presented for cataract surgery. These cuts were circular and hexagonal in nature. (See Figure 4.) The patient presented with a best spectacle-corrected visual acuity of:
OD: -.50 – 4.00 X 100 20/40
OS: +.25 – 3.50 X 58 20/60
The patient’s DED was treated with an immunomodulator, a DED-specific nasal spray, and a semifluorinated alkane solution.
The goal for this patient was to go from hyperopia to myopia by inducing .50 extended depth of focus. The LAL was chosen, as it is capable of 4.00 D of steepening in either meridian, and 3.25 D of flattening in either meridian. Therefore, I aimed for ~ +1.00 D of hyperopia and steepened the flat meridian by 1.00 D, taking the burden off the residual treatment for astigmatism.
The patient’s final outcome, with some vision fluctuation, without correction:
OD: 20/30
OS: 20/25
BSCVA OD: +2.50 -2.25 X 100 20/20-2
BSCVA OS: -.50 -.25 X 85 20/20-2
The patient sees well at near and distance now, but if she desires better distance OD, we will plan PRK.
Happy patients
RK patients have difficulty achieving the post-cataract surgery refractive target, so having flexibility in IOL adjustments has been life changing for these patients. CP
