Small Aperture Intraocular Lens Implantation Provides Excellent Outcomes In Patients With History Of Radial Keratotomy (Rk)

Retrospectively evaluated visual and refractive outcomes of the IC8 (Bausch and Lomb) small aperture lens in eyes with previous RK surgery. The optimal method of lens calculation and parameters influencing refractive outcomes were also evaluated.

Centre for Sight, UK - private ambulatory surgical centre

8 consecutive eyes (5 patients) were evaluated. Because of keratometric index changes in post-RK eyes, Equivalent K readings (EKR65) values (Pentacam) and Holladay 2 IOL formula were used targeting for mild myopia (Method 1). This was compared with the Holladay 2 formula using standard IOL master 500 K values (Method 2). UDVA, CDVA, UIVA, UNVA, dysphotopsias, keratometry and complications were recorded. Low-infusion pressure phacoemulsification surgery and scleral incision were performed to reduce magnitude of RK wound dehiscence.

Mean preop K values were steeper in EKR65 compared to IOL master K readings (mean difference of 0.60D± 0.94D). Mean preop SE was -0.90D±3.24D (-7.50D to +2.00D). At final postop SE was +0.39D±0.86D (-0.50D to +2.00D). UDVA was ≥6/7.5 in 7 of 8 eyes (87.5%). UIVA was ≥6/12 in 100%. UNVA was ≥6/12 in 87.5%. Mean predictive error of Method 1 and Method 2 were 1.01D and 0.30D respectively. SE ±1.00D using EKR65 was 60% vs 100% with IOL master Ks. Mean Day 1 keratometric flattening was 1.13D±0.76D (0.5D to 2.8D) and  0.19D±0.63D (-0.59D to 0.80D) at 6 weeks postop worse in an eye with 16 cut RK. Starbursts present preop in 2 patients resolved. Postop refractive cyl was less (p<0.05) than corneal cyl with mean difference of 0.60D±0.42D

Following RK, IC8 small aperture intraocular lens implantation achieves excellent and predictable visual outcomes with good range of focus and eliminates starbursts. Corneas are flatter immediately postop and do not always recover fully. As a result of long term postop corneal flattening, the use of flatter IOL master K readings results in a lower predictive error than the steeper EKR65 readings which measures the anterior and posterior curvatures. Modified surgical techniques with correct surgical wound placement and low fluidic parameters are important to reduce the risk of significant postoperative corneal flattening with more predictable outcomes.