Hit Or Miss? Primary Visual Outcomes Of Using Toric Edof Intraocular Lens In Cataract Surgery Of A Patient Who Underwent Two Refractive Surgeries: Radial Keratotomy With Subsequent Photorefractive Keratectomy On Both Eyes

This case report evaluated the visual outcomes of a patient who underwent phacoemulsification, implanted with toric extended depth of focus (EDOF) intraocular lens (IOL) (RayOne EMV IOL RAO200E, Rayner Intraocular Lenses Ltd., Worthing, UK) in both eyes with history of two refractive surgeries: radial keratotomy (RK) with subsequent photorefractive keratectomy (PRK).

A 66-year-old female came to the Eye Center of Medical Center Paranaque in Manila for continuation of her treatment for glaucoma in the left eye. The patient also came in complaining of decreased vision and glare on both eyes. Upon examination of the glaucoma specialist, there were RK cuts on the cornea of both eyes and bilateral cortical cataract reaching the pupil area thus this referral to refractive surgery service for management.

This is a case of a patient who had a history of RK forty-two years ago, with four RK cuts on the right and eight on the left. The patient also had PRK on both eyes twelve years ago. Prior to deciding which IOL calculator to use, corneal status was assessed using two corneal tomography machines: Oculus Pentacam (Pentacam AXL, Oculus, Germany) and Anterion (Heidelberg Engineering GmbH, Germany). For biometry, IOL Master 700 (Carl Zeiss, Meditec, Jena, Germany) was used. With two refractive surgeries done on both eyes, choosing the right IOL formula presents a challenging dilemma. Barrett True-K Toric Calculator for post-Radial Keratotomy was the option used for choosing the IOL power rather than the Barrett True-K Toric for post-Myopic LASIK. Target refraction on both eyes was plano.

Primary visual outcomes were uncorrected visual acuity (UCVA) at 4 meters, uncorrected intermediate visual acuity (UIVA) at 66 centimeters and uncorrected near visual acuity (UNVA) at 40 centimeters. One month post-cataract surgery, IOL in both eyes were noted to be on the proper axis. UCVA of the right eye was 20/15 with manifest refraction spherical equivalent (MRSE) of -1.25 diopter sphere, UIVA was 20/20 and UNVA was 20/25. However, the left eye UDVA was 20/50 with MRSE of +2.50 diopters sphere, UIVA was 20/70 and UNVA was 20/100.  Even though the left eye was exhibiting progressive hyperopic shift after the surgery, bilateral UDVA and UIVA were 20/20, and bilateral UNVA  was 20/32.

Even with the latest IOL calculators and biometry machines, post-RK IOL calculation is still challenging due to compromised corneal biomechanics, complex optical system and progressive hyperopic shift. The number of RK cuts may also be considered an important factor affecting the visual outcomes. Corneal biomechanics is more stable with 4 RK cuts thus hitting excellent target visual outcomes in contrast to the eye with 8 RK cuts. Also, refractive surgeries after RK may have contributed to less accurate IOL calculations. Therefore, with still unpredictable results, patients’ expectations should be managed with caution and possible options must be discussed to address the refractive surprise that may arise from missed target visual outcomes.