LASIK surgery in patients with residual refractive errors after radial keratotomy

AIMTo study the results and complications of LASIK surgery after radial keratotomy.

Cataract surgery on post radial keratotomy patients

This study aims to evaluate and to compare three different approaches of cataract surgery to patients with previous radial keratotomy（RK）, and to analyze the mechanical properties of the cornea after cataract surgery. Three groups of patients, each one including 8 eyes of patients with 16 RK incisions. The first group includes eyes with the first cataract incision superiorly, the second group in the temporal area, the third group in temporal area and a precautionary stabilizing suture across the RK incision adjacent to the main tunnel. In the first group intraoperative dehiscence occurred in three eyes（37.5%）： it required immediate application of a suture. In the second group dehiscence occurred intraoperatively in two radial scars（20%）： it required immediate application of a suture. In the third group, no intraoperative dehiscences were observed. The stabilizing suture of the RK incision works safer, with a lower risk of dehiscences and less postoperative astigmatism.

INDICATIONS AND PATIENTS' SELECTION FOR RADIAL KERATOTOMY

This paper sums up the indications and patients selection for Radial Keratotomy, including necessary presurgery examination, the age for surgery in myopia and predictability. It benefits the recognization for developing this surgery.

Eleven-year Experience with Radial Keratotomy

1 900 consecutive eyes that underwent radial keratotomy by the senior author were evaluated retrospectively. 3 months after surgery, minimum reduction in mean spherical equivalent of 0. 67D was achieved with 1 incision and maximum 7. 250 with 24 incisions. Unconnected visual acuity of 20/40 or better was obtained in 99. 4% of eyes with low myopia, 64. 2% with moderate myopia and 32. 4% with high myopia. For anisometropia, bilateral RK reduced refractive error from -12. 12D to -5. 22D in more myopic eyes...

Comparative results of corneal curvature measurements with three different keratometers after radial keratotomy

Background Corneal curvatures measured by conventional instruments after refractive surgeries were greater than the real values. This study on the instruments and methods for measuring corneal curvature was carried out with the aim of determining an accurate, simple and effective method to evaluate corneal refractive power after radial keratotomy （RK）. Methods A retrospective study was carried out on 52 eyes of 42 patients with a history of RK. The postoperative measurements after RK were performed with a manual keratometer （Rodenstock, Munchen-Hamburg, Germany）, a corneal topographer （Tomey TMS-1） and an automated IOLMaster keratometer （Carl Zeiss GmbH, USA）. The results obtained from analyzing clinical histories （clinical history method, CHM） were compared to the postoperative measurements with a two-way analysis of variance. Adjusted keratometry was used to correct the corneal central refractive power （K） values of the three keratometers. The CHM results were also compared to the corrected K values obtained with the three keratometers using the same statistical method. Results The smallest mean value was found for the CHM （（36.61±2.23） diopters）. The K values obtained with the CHM were very different from the results obtained with the three different instruments. The corrected K values obtained with the IOLMaster were the closest to the K values from the CHM. Conclusions It was shown that K values from measurements with the three instruments were higher. When the power of the intraocular lens of the patients after RK was calculated, the errors of the K values measured with the instruments should be taken into consideration.

Implantable collamer lens for residual refractive error after corneal refractive surgery

AIM：To assess the safety,efficacy,predictability and stability of implantable collamer lens（ICL） for residual refractive error after corneal refractive surgery.METHODS： This study evaluated 19 eyes of 12 patients who underwent ICL implantation after corneal refractive surgeries.They were followed up for 1y to 5y of uncorrected distance visual acuity（UDVA）,corrected distance visual acuity（CDVA）,manifest refractive error,flat and steep K value,axial length,intraocular pressure,corneal endothelial cell density,adverse events after ICL surgery.RESULTS： The mean follow-up period was 39.05 ±19.22 mo（range,1-5y）.Spherical equivalent refractive error changed from-7.45±3.02 D preoperatively to-0.85±1.10 D 1wk to 1mo after ICL implantation,with the safety and efficacy indices being 1.12 and 1.15,respectively.A total of 52.63% of eyes were within ±0.5 D of the predicted spherical equivalents,73.68% were within ±1.0 D.A trend of mild regression towards myopia with axial elongation after 5y was observed.One eye with mild anterior capsule opacity and retinal detachment 1y after surgery were observed.CONCLUSION： ICL implantation is safe and effective for the correction of residual refractive error after corneal refractive surgeries,especially in moderate to high residual myopia.

Accuracy and safety of partial thickness femtosecond laser radial and arcuate keratotomy incisions in porcine eyes

Background:To evaluate the accuracy and safety of micro radial and arcuate keratotomy incisions constructed by a femtosecond laser system with a curved contact patient interface in porcine eyes.Methods:Partial thickness micro radial and arcuate keratotomy incisions were constructed in porcine eyes with a femtosecond laser system and evaluated for precision of depth,quality,and consistency.Optical coherence tomography was used to determine the accuracy and precision of incision depth.Corneal endothelial safety was assessed by a fluorescent live/dead cell viability assay to demonstrate laser-induced endothelial cell loss.Quality was evaluated by ease of opening and examination of interfaces.Results:In two micro radial incision groups,intended incision depths of 50%and 80%resulted in mean achieved depths of 50.01%and 77.69%,respectively.In three arcuate incision groups,intended incision depths of 80%,600μm or 100μm residual uncut bed thickness resulted in mean achieved depths of 80.16%,603.03μm and residual bed of 115μm,respectively.No loss of endothelial cell density occurred when the residual corneal bed was maintained at a minimum of 85-116μm.The incisions were easy to open,and interfaces were smooth.Conclusions:A femtosecond laser system with curved contact interface created precise and reproducible micro radial and arcuate keratotomy incisions.Accuracy and precision of the incision depth and preservation of endothelial cell density demonstrated the effectiveness and safety of the system.