Bilateral femtosecond laser-enabled intrastromal astigmatic keratotomy to correct high post-penetrating keratoplasty astigmatism

Post-penetrating keratoplasty astigmatism

Postoperative astigmatism is one of the common complications affecting visual outcomes after a penetrating keratoplasty. It can result from various factors related to host, donor and surgical technique, resulting in suboptimal visual outcome. While some of the measures taken during preoperative planning and during actual surgery can reduce the magnitude of postoperative astigmatism, postoperative correction of astigmatism is often required in cases with high degrees of astigmatism. When spectacles and contact lenses fail to provide optimal visual outcomes, various surgical techniques that include astigmatic keratotomy, compression sutures, toric intraocular lens placement, and laser refractive procedures can be considered. When none of these techniques are able to achieve a desired result with in the acceptable optical range, a repeat keratoplasty is considered a last option. We discuss the various causes and management of complication of postoperative astigmatism occurring after a full thickness corneal transplantation surgery.

Femtosecond laser in refractive corneal surgery

The introduction of the femtosecond (fs) laser has revolutionized ophthalmic surgery. With the worldwide application of fs-lasers, clinical outcomes and safety in corneal procedures have improved significantly and they have become an ideal tool for ultra-precise corneal refractive surgery. Flap creation in laser in situ keratomileusis (LASIK) is the most common use of this laser. It can also be used for other corneal refractive procedures including channel creation for the insertion of intrastromal corneal ring segments (ICRS), performing astigmatic keratotomies (AK), femtosecond lenticule extraction including small incision lenticule extraction (SMILE), and the insertion of corneal inlays. This article summarizes recent advanced applications of fs laser technology in corneal refractive surgery.

Comparison of manual and femtosecond laser arcuate keratotomy procedures for the correction of post-keratoplasty astigmatism

Purpose

To compare the effectiveness of femtosecond laser (FSL) assisted and manual arcuate keratotomy (AK) procedures for the correction of postkeratoplasty astigmatism.

Methods

Fifty-two eyes (52 patients) were treated with FSL assisted AK and 53 eyes (51 patients) with manual AK for post-keratoplasty astigmatism. The main outcome measures included preoperative and postoperative manifest refraction, uncorrected and corrected distance visual acuity (UDVA, CDVA), corneal topography and complications.

Results

In FSL group, UDVA changed significantly from 0.90 ± 0.43 preoperatively to 0.60 ± 0.39 at last follow-up (p = 0.001). In manual group, preop- (0.87 ± 0.35) and post-operative UDVA (0.93 ± 042) were comparable (p = 0.535). CDVA improved from 0.30 ± 0.18 preoperatively to 0.20 ± 0.14 at last follow-up visit in FSL group (0.014) and 0.28 ± 0.15 preoperative to 0.23 ± 0.19 at last postoperative visit (0.074) in manual group. Postoperative UDVA and CDVA were comparable between both the groups (p > 0.05). The mean preoperative refractive cylinder was 6.38 ± 3.73 and 7.15 ± 132, decreasing significantly to 5.06 ± 2.06 and 5.19 ± 2.25 after manual and FSL assisted AK procedures respectively. Mean change in the refractive cylinder was −1.10 ± 4.11 in manual AK group and −2.19 ± 2.35 in FSL group (p = 0.134). Perforation, overcorrection and regression occurred in respectively 3 eyes (5.8%), 12 eyes (23.07%) and 1 eye (1.92%) in FSL group and 1 eye (1.9%; macro-perforation), 7 eyes (13.21%) and 8 eyes (15.09%) in manual group. Additionally, in the manual group, severe ectasia occurred in 1 eye (1.9%).

Conclusion

FSL assisted AK procedure is comparable or to a certain extent better regarding safety and efficacy than manual AK procedure. Postoperatively, FSL resulted in better outcomes of UCVA, BCVA, refractive cylinder and keratometric astigmatism compared to the manual AK procedures; although, the difference between the groups was not statistically significant.

Deep Intrastromal Arcuate Keratotomy With In Situ Keratomileusis (DIAKIK) for the Treatment of High Astigmatism After Keratoplasty: 2-Year Follow-up

PURPOSE

To describe 2-year results of deep intrastromal arcuate keratotomy with in situ keratomileusis (DIAKIK) for the treatment of high astigmatism after keratoplasty.

METHODS

This prospective study included 20 eyes from 20 patients presenting with high astigmatism after keratoplasty. All were treated by two-step femtosecond laser surgery, with two intrastromal arcuate keratotomies and a corneal flap, followed a few months later by excimer photoablation after reopening of the flap.

RESULTS

At 24 months, both uncorrected (UDVA) and corrected (CDVA) distance visual acuity had improved from 1.12 ± 0.42 logMAR (20/200 Snellen) before surgery to 0.58 ± 0.23 logMAR (20/80 Snellen) (P < .001) and from 0.31 ± 0.26 logMAR (20/40 Snellen) to 0.20 ± 0.20 logMAR (20/32 Snellen) (P = .04), respectively. The mean spherical equivalent improved from -5.01 ± 4.35 to -1.54 ± 2.42 diopters. The mean efficacy index was 0.63. The mean correction index was 0.93 ± 0.32. The mean flattening index was 1.09 ± 0.75 and the mean safety index was 1.39. No graft rejection or epithelial ingrowth was observed.

CONCLUSIONS

This two-step procedure was an effective treatment for high astigmatism after keratoplasty. The use of both femtosecond and excimer lasers helped to avoid some complications that would have jeopardized the grafts. Refractive and topographic stability was good 2 years after surgery. [J Refract Surg. 2019;35(4):239-246.].

Novel method for preventing cyclorotation in Ziemer Femto LDV Z8 femtosecond laser-assisted cataract surgery with Verion image-guided system

Purpose

To investigate the feasibility of a new method involving the use of the Verion image-guided system in preventing cyclorotation during femtosecond laser-assisted cataract surgery (FLACS).

Patients

Our preliminary data included details of 24 consecutive patients. All patients underwent cataract surgery at Universal Eye Center, Zhong-Li, Taiwan, between December 2016 and January 2017.

Methods

We developed a technique to use the Verion image-guided system in FLACS and evaluated whether this new technique is compatible with Femto LDV Z8. The Verion image-guided system was used to prevent misalignments. The only additional step in this technique is using a marking tool to place ink on the corneal limbus (at 3 and 9 o’clock positions) guided by the Verion digital marker system. Remaining procedures could be performed using the touchscreen of Femto LDV Z8 to calibrate the horizontal reference axis.

Results

This study included 24 patients who underwent cataract surgery. The technique used could effectively neutralize misalignments at an average of 8.08° and 2.66° in clockwise and counterclockwise directions, respectively.

Conclusion

This technique combines the advantages of iris fingerprinting technology and mobile features of Femto LDV Z8, has fewer transfer steps, improves centration of the eyes, and, most importantly, can prevent misalignments through cyclotorsion or docking procedures. Furthermore, this method can improve the accuracy of arcuate incisions and toric intraocular lens alignment in astigmatism correction.

Femtosecond laser-assisted astigmatic keratotomy: a review

Background

Astigmatic keratotomy (AK) remains an accessible means to correct surgically induced or naturally occurring astigmatism. The advantages of femtosecond laser-assisted astigmatic keratotomy (FSAK) over conventional methods have been recognized recently.

Main text

This review evaluates the efficacy, complications, and different methods of FSAK for correction of astigmatism in native eyes and those that underwent previous penetrating keratoplasty (PKP).

The penetrating and intrastromal FSAK (IFSAK) techniques can reduce post-keratoplasty astigmatism by 35.4% to 84.77% and 23.53% to 89.42%, respectively. In native eyes, the penetrating and IFSAK techniques reduce astigmatism by 26.8% to 58.62% and 36.3% to 58% respectively, implying that the magnitude of the astigmatic reduction is comparable between the two FSAK procedures. Nonetheless, IFSAK offers the additional advantages of almost no risk of infection, wound gape, and epithelial ingrowth. The use of nomograms, anterior-segment optical coherence tomography, and consideration of posterior cornea and corneal biomechanics are helpful to enhance the efficacy and safety of FSAK. The complications of FSAK in eyes that underwent PKP include overcorrection, visual loss, microperforations, infectious keratitis, allograft rejection, and endophthalmitis. The reported difficulties in native eyes include overcorrection, anterior gas breakthrough, and suction loss.

Conclusions

In eyes that underwent PKP, FSAK effectively reduces high regular or irregular astigmatism, with rare and manageable complications. Nevertheless, the drawbacks of the procedure include the potential loss of visual acuity and low predictability. For native eyes undergoing femtosecond laser-assisted cataract surgery, IFSAK is a good choice to correct low astigmatism (< 1.5 diopters). The refractive effect of astigmatism from the posterior cornea needs to be considered in the nomograms for native eyes undergoing refractive cataract surgery. To further improve the efficacy of FSAK, more large-scale randomized studies with longer follow-up are needed.

Post-keratoplasty astigmatism management by relaxing incisions: a systematic review

Postoperative visual acuity can be limited by post-keratoplasty astigmatism, even with a clear corneal graft. Astigmatism management can be performed by selective suture removal, adjustment of sutures, optical correction, photorefractive procedures, wedge resection, intra-ocular lens implantation, intracorneal ring segments, relaxing incisions with or without compression sutures and repeated keratoplasty. Relaxing incisions can be made in the graft, graft-host interface or host cornea. Despite the unpredictability of the method because the flat and steep meridians are usually not orthogonal after penetrating keratoplasty, with asymmetric power distribution, all the studies showed an overall reduction of refractive, keratometric or topographic astigmatism, ranging from 30% to 72% with manual or femtosecond-assisted techniques. Most patients with astigmatism higher than 6 diopters had residual cylinder less than or equal to 3 diopters, which can be treated by laser excimer ablation or secondary intraocular lens implantation.

Corneal Astigmatism and Aberrations After Combined Femtosecond-Assisted Phacoemulsification and Arcuate Keratotomy: Two-Year Results

PURPOSE

To investigate the stability of corneal astigmatism and higher-order aberrations after combined femtosecond-assisted phacoemulsification and arcuate keratotomy.

DESIGN

Retrospective, interventional case series.

METHODS

Surgery was performed using a VICTUS (Bausch & Lomb Inc, Dornach, Germany) platform. A single, 450-μm deep, arcuate keratotomy was paired at the 8-mm zone with the main phacoemulsification incision in the opposite meridian. The keratotomy incisions were not opened. Corneal astigmatism and higher-order aberration measurements obtained preoperatively and at 2 months and 2 years postoperatively were analyzed.

RESULTS

Fifty eyes of 50 patients (mean age 66.2 ± 10.5 years) were included. The mean preoperative corneal astigmatism was 1.35 ± 0.48 diopters (D). This was reduced to 0.67 ± 0.54 D at 2 months and 0.74 ± 0.53 D at 2 years postoperatively (P < .001). There was no statistically significant difference between postoperative corneal astigmatism over 2 years (P = .392). Both magnitude of error and absolute angle of error were comparable between the 2 postoperative time points (P > .283). At postoperative 2 months and 2 years, 72% and 70% of eyes were within 15 degrees of preoperative meridian of astigmatism, respectively. All wavefront measurements increased significantly at 2 months and 2 years (P < .007), except spherical aberration (P > .150). There was no significant difference in higher-order aberrations between 2 months and 2 years postoperatively (P > .486).

CONCLUSIONS

Our study showed the stability of femtosecond-assisted arcuate keratotomy. Further studies using other platforms and nomograms are needed to corroborate the findings of this study.

Combined intrastromal astigmatic keratotomy and laser in situ keratomileusis flap followed by photoablation to correct post-penetrating keratoplasty ametropia and high astigmatism: One-year follow-up

PURPOSE

To evaluate a new technique combining intrastromal astigmatic keratotomy (AK) with a laser in situ keratomileusis (LASIK) flap followed by excimer laser photoablation to correct post-penetrating keratoplasty (PKP) high astigmatism and ametropia.

SETTING

Kasr El Aini Hospital, Cairo University, Cairo, Egypt.

DESIGN

Prospective interventional uncontrolled case series.

METHODS

Patients with post-PKP high astigmatism and ametropia had paired intrastromal AK with LASIK flap using the M2 microkeratome followed 2 to 3 months later by excimer laser photoablation. The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), mean refractive spherical equivalent (SE), and mean cylinder after each step and at the 1-year follow-up.

RESULTS

The study comprised 20 eyes (20 patients). All parameters were significantly improved in all patients by the last follow-up visit. The mean UDVA improved from 1.07 logMAR ± 0.2 (SD) preoperatively to 0.23 ± 0.18 logMAR (P < .001), the mean CDVA improved from 0.79 ± 0.18 logMAR to 0.12 ± 0.12 logMAR (P < .001), the mean refractive SE improved from -5.04 ± 2.62 diopters (D) to -1.47 ± 1.32 D (P = .001), and the mean cylinder reduced from -5.39 ± 0.98 D to -1.05 ± 0.71 D (P < .001). The mean correction index was 0.84 ± 0.10, and the mean flattening index was 0.83 ± 0.10. Thirty-five percent of cases developed microperforations, and 15% developed epithelial ingrowth.

CONCLUSION

This combined approach allowed for the correction of high astigmatism and ametropia following PKP; however, epithelial ingrowth requiring intervention is a complication to be considered.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Femtosecond laser-assisted cataract surgery--current status and future directions

Femtosecond laser-assisted cataract surgery (FLACS) putatively offers several advantages over conventional phacoemulsification. We review the current status of FLACS and discuss the evolution of femtosecond lasers in cataract surgery and the currently available femtosecond laser platforms. We summarize the outcomes of FLACS for corneal wound creation, limbal relaxing incisions, capsulotomy, and lens fragmentation. We discuss surgical planning, preoperative considerations, clinical experiences including the learning curve and postoperative outcomes with FLACS, and also the cost effectiveness of FLACS. We present the intraoperative complications and management of challenging cases where FLACS offers an advantage and also speculate on the future directions with FLACS. Further advancements in laser technology to refine its efficacy, advancement in intraocular lens design to harness the potential benefits of FLACS, and a reduction in cost are needed to establish a clear superiority over conventional phacoemulsification.

Femtosecond laser cataract surgery

Femtosecond laser (FSL) cataract surgery is in its infancy but is rapidly gaining popularity due to the improved consistency and predictability for corneal incisions and anterior capsulorhexis. It enables subsequently less phacoemulsification energy and time to be employed, which has gains in terms of reduced corneal oedema. In addition, the FSL allows better circularity of the anterior capsulotomy, capsule overlap, intraocular lens (IOL) placement and centration of the IOL. These advantages have resulted in improved visual and refractive outcomes in the short term. Complication rates are low which reduce with surgeon experience. This review article focuses on the Alcon LenSx system.