Femtosecond-laser arcuate wedge-shaped resection to correct high residual astigmatism after penetrating keratoplasty

Predicting the impact of femtosecond-assisted arcuate keratotomy combined with tri-planar clear corneal incisions on astigmatism in implantable collamer lens surgery: one-year follow-up

PURPOSE

To investigate the factors associated with and impact on the femtosecond-assisted (FS-assisted) limbal relaxing incision (LRI) combined with the steep-meridian tri-planar clear corneal incision (TCCI) to reduce astigmatism in patients undergoing Implantable Collamer Lens (ICL) surgery.

METHODS

Retrospective case series. The study reviewed patients with ICL surgery combined with FS-assisted LRIs paired with steep-meridian TCCIs. Correlation analysis examined the relationship between independent variables, including preoperative characteristics (intraocular pressure, corneal thickness, axial length, et al.), TCCI, and LRI surgical parameters. The predictors of surgically induced astigmatism (SIA) were determined using individual-level analysis and accounting for inter-eye correlation with the generalized estimating equation (GEE).

RESULTS

The study enrolled 69 patients, with 114 eyes (55 right and 59 left). The mean spherical equivalent (SEQ) was - 10.29 ± 2.99D and - 9.99 ± 2.72D for the right and left eye, respectively, while the mean preoperative corneal astigmatism was - 1.54 ± 0.47D and - 1.54 ± 0.46D for the right and left eyes, respectively. After 12 months of follow-up, univariate analysis revealed significant correlations between SIA and intraocular pressure (IOP), astigmatism type, TCCI position (degree), peripheral corneal thickness (PCT), LRI arc incision diameter, post depth (%), and angle, respectively (P = 0.046, 0.016, 0.039, 0.040, 0.009, 0.000, 0.000). Multivariate analysis using GEE demonstrated that axial length (AL), astigmatism type, LRI arc diameter, and angle were independent predictors of SIA (P = 0.000, 0.005, 0.029, 0.000).

CONCLUSIONS

The type of astigmatism and axial length were independent factors that affected SIA when modifying the LRI arc diameter and angle through FS-assisted steep-meridian TCCI paired with LRI in ICL surgery.

Changes in post-keratoplasty astigmatism after suture removal: refraction vs tomography vs aberrometry

AIM

To analyse the changes in magnitude and orientation of astigmatism after suture removal (SR) in keratoplasty eyes as measured by refraction, tomography, and aberrometry.

METHODS

Twenty-six eyes of 25 patients after optical keratoplasty requiring SR to reduce the astigmatism during the follow-up period were prospectively included. Eyes with poor quality topography scans or if there were no sutures in the steepest semi meridian were excluded. Corrected distance visual acuity (CDVA), manifest refraction, corneal tomography and aberrometry were performed on all patients before and after SR.

RESULTS

The mean age of the patients was 40.8±14.4y. Penetrating keratoplasty was performed in 23 eyes (89%) and deep anterior lamellar keratoplasty was done in 3 eyes (11%). There was a statistically significant reduction in the magnitude of refractive, tomographic and aberrometry astigmatism after SR (P<0.001) at 2h after suture removal. The mean net reduction of the astigmatism was greater as measured by corneal tomography compared to refractive astigmatism (P<0.05). There was no statistically significant change in refractive astigmatism between 2h and 2mo after SR (P=0.55). Vector calculations demonstrated a greater amount of undercorrection in the tomography group and the rotational error was more towards counterclockwise direction. Mean monocular logMAR CDVA improved from 0.57 D to 0.49 D after SR (P=0.002).

CONCLUSION

The net reduction in the magnitude of astigmatism after SR is greater in the tomography and aberrometry groups. With one episode of SR, there is no difference in the aberration profile.

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.

Application of Femtosecond Laser in Anterior Segment Surgery

Femtosecond laser (FSL) is a near-infrared laser that can create reliable and reproducible tissue cutting with minimal damage to adjacent tissue. As the laser can also create incisions with various orientations, depths, and shapes, it is expected to be a useful tool for anterior segment surgery, such as cornea, refractive, and cataract surgery. In this review, the authors will introduce the application of FSL in various anterior segment surgeries and discuss the results of studies regarding the efficacy and safety of FSL in cornea, refractive, and cataract surgery. Experimental studies regarding the potential use of FSL will also be introduced. The studies discussed in this review suggest that FSL may be a useful tool for improving the prognosis and safety of surgeries of the anterior segment.

Long-term Results of Corneal Wedge Resection for High Postkeratoplasty Astigmatism

PURPOSE

To present the results of corneal wedge resection in postkeratoplasty astigmatism, performed by the same surgeon using the same nomogram over a 25-year period.

METHODS

This is a retrospective observational study. The sample was obtained from the medical records of all patients who underwent penetrating or deep lamellar keratoplasty, performed by a single surgeon from 1993 to 2018. All surgeries were performed using a diamond knife, on the flat meridian, involving the keratoplasty scar and closed with five 10-0 nylon sutures.

RESULTS

A total of 39 eyes were included. The keratometry measured cylinder improved from 7.99 ± 0.25 to 2.5 ± 0.3 D at 12 months and remained stable thereafter (a mean follow-up of 76.3 months). Best spectacle corrected visual acuity increased from 0.35 ± 0.01 to 0.57 ± 0.02 at 12 months and remained stable thereafter. There was a coupling ratio of 0.08 ± 0.03 D at 12 months. There were no corneal graft rejections or loss of best spectacle corrected visual acuity on this series.

CONCLUSIONS

Corneal wedge resection is a valuable resource for the management of high postkeratoplasty astigmatism. It is a safe and reproducible procedure, with stable results at 12 months and thereafter.

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.

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.

A Novel Corneal Remodeling Technique for the Management of Keratoconus

PURPOSE

To describe a novel technique to reshape the ectatic cornea by means of crescent keratectomy performed with an excimer laser using a mask.

METHODS

A crescent-shaped perforation at the base of the mask allowed the laser ablation to be directed only to the intended region, shielding the remaining cornea. This technique was performed in 3 eyes of 3 patients with keratoconus grade 2 to 3. Arcs of 180° and 360° had been performed depending on the severity of the keratoconus. The edges of the crescent were closed by 10-0 nylon interrupted sutures.

RESULTS

At 1 year postoperatively, all cases showed improvement in visual acuity, keratometry, and corneal topography. The treatment also reduced optical aberrations and shortened the anterior chamber depth.

CONCLUSIONS

Although the preliminary results are promising, there is a need to standardize a nomogram of this technique for treating keratoconus. [J Refract Surg. 2017;33(12):854-856.].

Management of post-keratoplasty astigmatism

Post-keratoplasty astigmatism remains a challenge for corneorefractive surgeons. While maintaining a healthy graft is the most crucial issue in keratoplasty procedures, astigmatism is a limiting factor in the visual rehabilitation of otherwise successful corneal grafts. The management of post-keratoplasty astigmatism takes place at 2 stages: when sutures are still present at the graft-host junction and when all sutures have been removed. Excessive suture-in post-keratoplasty astigmatism is usually managed by selective suture manipulation, ie, suture adjustment and/or suture removal along the steep meridian of astigmatism. A small amount of suture-out post-keratoplasty astigmatism can be managed by spectacles. Higher magnitudes of astigmatism can be addressed by contact lenses or surgical intervention, such as relaxing and compressing procedures. Laser lamellar refractive surgery can also be used to manage post-keratoplasty astigmatism, and toric phakic intraocular lenses have recently been recommended. In this review, we discuss the etiology and management of post-keratoplasty astigmatism and provide recommendations and tips to minimize it.

FINANCIAL DISCLOSURE

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

[Astigmatism correction by femtosecond laser]

Through the creation of astigmatic keratotomies, femtosecond laser can correct congenital or post-surgical astigmatism. We have been using an optimized treatment nomogram, which offers superior and more predictable results than manual incisional techniques. Femtosecond arcuate incisions allow a reduction of over 50% of the preoperative astigmatism. Nonetheless, the efficacy can likely be improved further by refining these nomograms specific to the femtosecond laser.

Current approaches for management of postpenetrating keratoplasty astigmatism

A successful corneal graft requires both clarity and an acceptable refraction. A clear corneal graft may be an optical failure if high astigmatism limits visual acuity. Intraoperative measures to reduce postkeratoplasty astigmatism include round and central trephination of cornea with an adequate size, appropriate sutures with evenly distributed tension, and perfect graft-host apposition. Suture manipulation has been described for minimising early postoperative astigmatism. If significant astigmatism remains after suture removal, which cannot be corrected by optical means, then further surgical procedures containing relaxing incisions, compression sutures, laser refractive surgery, insertion of intrastromal corneal ring segments, wedge resection, and toric intraocular lens implantation can be performed. When astigmatism cannot be reduced using one or more abovementioned approaches, repeat penetrating keratoplasty should inevitably be considered. However, none of these techniques has emerged as an ideal one, and corneal surgeons may require combining two or more approaches to exploit the maximum advantages.

Comparison of astigmatic keratotomy results in deep anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus

PURPOSE

To compare astigmatic keratotomy (AK) outcomes in high astigmatism after deep anterior lamellar keratoplasty (DALK) and after penetrating keratoplasty (PK) in keratoconus patients.

DESIGN

Prospective, comparative, interventional case series.

METHODS

This study comprised 20 eyes that underwent DALK and 24 eyes that underwent PK. After suture removal, all eyes had more than 5 diopters (D) of astigmatism and underwent standard manual 1-pair, 90-degree, and 90% corneal thickness AK incisions. The main outcome measures included preoperative and postoperative manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity, surgically induced astigmatism, Orbscan II (Bausch & Lomb) corneal topography results, keratometric astigmatism, and complications.

RESULTS

All eyes completed 6 months of follow-up. The overcorrection rate was 35% and 41.6% in the DALK and PK groups, respectively (P=.75). At 6 months after AK, logarithm of the minimal angle of resolution uncorrected visual acuity improved from 0.88 ± 0.20 to 0.54 ± 0.26 and from 1.0 ± 0.34 to 0.53 ± 0.26 in the DALK and PK groups, respectively (P=.01 to P<.01). Best spectacle-corrected visual acuity improved from 0.16 ± 0.09 to 0.13 ± 0.08 and from 0.16 ± 0.12 to 0.11 ± 0.08 in the DALK and PK groups, respectively (P=.13 to P=.01). The mean refractive cylinder was decreased 2.74 ± 1.44 D in the DALK group and 3.18 ± 2.96 D in the PK group (P=.35). Surgically induced astigmatism was 6.10 ± 3.27 D in the DALK group and 7.15 ± 2.98 D in the PK group (P=.36).

CONCLUSIONS

The manual AK for the treatment of postkeratoplasty astigmatism after DALK and PK in keratoconus patients is a safe and effective surgical procedure, allowing similar refractive cylinder reduction and improvement in uncorrected visual acuity and best spectacle-corrected visual acuity.

Femtosecond laser-assisted decagonal penetrating keratoplasty

PURPOSE

To assess the use of a new polygonal trephination pattern for penetrating keratoplasty (PK) assisted by femtosecond laser.

DESIGN

Prospective, nonrandomized clinical study.

METHODS

Sixteen eyes underwent decagonal PK. Nine had Fuchs dystrophy, 4 had pseudophakic bullous keratopathy, 1 had experienced trauma, 1 had corneal amyloidosis, and 1 had keratoconus. A Femtec (Tecnolas PerfectVision) laser was used to create decagonal penetrating cuts on both donor and recipient corneas. All patients were evaluated for uncorrected visual acuity, best spectacle-corrected visual acuity, pachymetry, topography, and endothelial cell density. Scanning electron microscopy was performed on corneal tissue after surgery.

RESULTS

All eyes were treated successfully without intraoperative complications. The mean follow-up ± standard deviation was 9.75 ± 3.5 months. Mean postoperative best spectacle-corrected visual acuity was 20/53, and there was a significant improvement in both uncorrected visual acuity (P = .0019) and best spectacle-corrected visual acuity (P = .001). At 6 months, mean ± standard deviation manifest astigmatism was 1.90 ± 1.20 diopters. Mean endothelial cell density was 1502 ± 458 cells/mm². Scanning electron microscopy displayed straight decagonal cut margins and minor remaining tissue bridges.

CONCLUSIONS

Use of the decagonal trephination profile was effective and safe to perform PK. Short-term visual results and refractive results are encouraging compared with those of conventional PK studies. Longer-term follow-up and comparative studies are necessary to determine precisely advantages the and optimal surgical settings of this technique.

[Arcuate keratotomy for postkeratoplasty astigmatism by femtosecond laser]

OBJECTIVE

Evaluation of the effectiveness of arcuate keratotomy performed with femtosecond laser for correction of postkeratoplasty astigmatism.

METHODS

This retrospective clinical study included 11 eyes. All cases underwent arcuate keratotomy using femtosecond laser. Outcome measures included visual acuity and endothelial cell density as well as refractive, keratometric, and topographic astigmatism. The incision depth was also evaluated by OCT-3.

RESULTS

With a mean follow-up of 7.4+/-6.7 months, uncorrected visual acuity was not modified and the mean best corrected visual acuity significantly improved from 1.68+/-1.59 lines (p=0.007). The mean preoperative refractive cylinder was 5.18+/-1.15D, decreasing to 3.41+/-1.93D (p=0.045) after laser-arcuate keratotomy. The reduction of preoperative keratometric (7.79+/-3.69D) and topographic (7.98+/-2.41D) astigmatism was higher, with a decrease to 4.81+/-2.52D (p=0.021) and 4.36+/-2.59D (p=0.005) postoperatively. Endothelial cell density was not modified after surgery. The difference between achieved and planned incision depth was -10.7+/-63.5mum. All cases were uncomplicated.

DISCUSSION

Arcuate keratotomies performed with the femtosecond laser were effective in reducing postkeratoplasty astigmatism and has a number of advantages over conventional techniques. However, efficacy could be improved by a more accurate nomogram.

CONCLUSION

Arcuate keratotomy performed with femtosecond laser is a relatively easy, safe, and effective means of treating postkeratoplasty astigmatism. Given our small sample, much larger series are needed to provide more confident estimates of astigmatism reduction proportions and to adjust correction parameters.

Correction of postkeratoplasty astigmatism by femtosecond laser compared with mechanized astigmatic keratotomy

PURPOSE

To compare the effectiveness of arcuate keratotomy (AK) performed with a femtosecond laser (FSL) or Hanna keratome (Moria, Anthony, France) for correction of postkeratoplasty astigmatism.

DESIGN

Prospective, randomized study.

METHODS

This clinical study included 20 eyes. Two groups of 10 eyes underwent AK using an FLS or keratome. Refractive and keratometric astigmatism were evaluated before surgery and 6 months after surgery. The astigmatic changes in the 2 groups were measured through arithmetic and vector analysis (Alpins method).

RESULTS

Six months after surgery, the mean uncorrected and corrected visual acuities did not change significantly. The mean preoperative refractive cylinder was 8.6 +/- 3.0 diopters (D) and 6.7 +/- 2.1 D, decreasing to 3.9 +/- 2.4 D and 4.7 +/- 2.4 D after laser AK and mechanized AK, respectively. The mean arithmetic change was significantly higher after laser AK, with a decrease of -55.4 +/- 20.7% (P = .011). Vector analysis showed a systematic undercorrection of astigmatism in both groups with a refractive correction index of 0.82 and 0.90 after laser AK and mechanized AK, respectively. Although no statistically significant differences were detected, a wider spread of angle of error and an almost significant difference of mean absolute angle of error (P = .052) suggest a larger misalignment of treatment during mechanized AK. All cases were uncomplicated after laser AK, 1 microperforation occurred and 1 case with off-center incisions occurred after mechanized AK.

CONCLUSIONS

AK performed with the femtosecond laser was effective in reducing postkeratoplasty astigmatism and has some advantages over conventional techniques. However, efficacy could be improved by a more accurate nomogram and alignment of treatment.

Femtosecond laser arcuate keratotomy for the correction of high astigmatism after keratoplasty

PURPOSE

To determine the feasibility and initial outcomes of using a femtosecond laser to perform arcuate keratotomies to correct high post-keratoplasty astigmatism.

DESIGN

Prospective noncomparative interventional case series.

PARTICIPANTS

Twelve eyes of 12 consecutive patients (mean age 44.9+/-9.5 years) who presented with a high degree of astigmatism, noncorrectable with spectacles or contact lenses (10 post-penetrating keratoplasty, 2 post-deep lamellar keratoplasty), and were candidates for relaxing incisional corneal surgery.

METHODS

The Femtec (20/10 Perfect Vision, GmbH, Heidelberg, Germany) femtosecond laser performed paired 90-degree angled arcuate incisions on the graft button. The incision sites and depths were programmed at 1.00 mm inside the graft edge and at 90% of the corresponding local graft thickness, whereas the angular lengths of the cuts were determined by analyzing the locations and extents of the steepest meridians in the topographic map.

MAIN OUTCOME MEASURES

Changes in uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), mean subjective and topographically determined astigmatism; imaging of incisions by anterior segment optical coherence tomography (AS-OCT); and wound healing by in vivo confocal microscopy (IVCM).

RESULTS

Postoperative follow-up extended to 6 months. Mean uncorrected logarithm of the minimum angle of resolution (logMAR) BSCVA and UCVA improved from preoperative values of 0.25+/-0.16 and 1.05+/-0.18 to 6-month values of 0.11+/-0.12 (standard deviation) and 0.55+/-0.34, respectively (P<0.05). Mean subjective astigmatism was 7.16+/-3.07 diopters (D) preoperatively and 2.23+/-1.55 D at 1 month after surgery (P = 0.002) and remained stable to the end of follow-up. Anterior segment optical coherence tomography image analysis showed that the depth and location of the incisions were consistent with the preoperative surgical plan. In vivo confocal microscopy showed mild edema and keratocyte activation along the incision edges, together with initial epithelial ingrowth inside the wound, followed by subsequent moderate fibrotic scarring.

CONCLUSIONS

Arcuate keratotomies performed with the femtosecond laser were effective in reducing post-keratoplasty astigmatism. Laser-generated incisions within the graft button presented precise geometry and reliable depth of incision, with a wound healing pattern characterized by epithelial ingrowth and mild fibrosis.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Histologic evaluation of human posterior lamellar discs for femtosecond laser Descemet's stripping endothelial keratoplasty

PURPOSE

To evaluate the histologic changes in corneal structure after femtosecond laser preparation of posterior lamellar discs, more specifically, the smoothness of the stromal bed and the accuracy of the predicted depth of the horizontal lamellar cut.

MATERIALS AND METHODS

Nineteen human donor eyes unsuitable for transplantation were used. Femtosecond laser was used to prepare a horizontal lamellar cut in donor corneas at a depth of 400 microm. Transmission electron microscopy images were used to evaluate the changes in the corneal structure and to measure the damage zone. Scanning electron microscopy images were used to determine the relative depth of the horizontal lamellar cut, and the stromal bed was examined to determine the smoothness of the surface.

RESULTS

Transmission electron microscopy images showed a mean damage zone of 6.8 +/- 3.1 microm, which consisted of irregularly oriented collagen fibrils and electron-dense granular material. The collagen lamellae, both anteriorly and posteriorly of the damaged zone, showed a regular parallel configuration. The relative depth of the horizontal lamellar cut as percentage of the total corneal thickness in the center and periphery was 70.4% +/- 4.5% and 55.6% +/- 5.9%. Scanning electron microscopy images of the stromal bed showed a relatively smooth surface.

CONCLUSION

The femtosecond laser is effective to prepare a deep horizontal lamellar cut in a standardized method. The stromal bed is smooth and without extensive adjacent tissue damage. The is thinner in the center and thicker at the edges, which may produce a mild hyperopic shift after femtosecond laser-assisted Descemet's stripping endothelial keratoplasty.

Femtosecond lasers in ophthalmology

PURPOSE

To provide an update and review of femtosecond (FS) lasers in clinical ophthalmology.

DESIGN

Perspective, literature review, and commentary.

METHODS

Selected articles from the literature and the authors' clinical and laboratory studies.

RESULTS

The FS laser employs near-infrared pulses to cut tissue with minimal collateral tissue damage. Although its major use at present is in the cutting of laser in situ keratomileusis flaps, the laser has proven its versatility in laser-assisted anterior and posterior lamellar keratoplasty, cutting of donor buttons in endothelial keratoplasty, customized trephination in penetrating keratoplasty, tunnel creation for intracorneal ring segments, astigmatic keratotomy, and corneal biopsy. Current laboratory studies include all-FS laser refractive keratomileusis sans flap, cutting corneal pockets for insertion of biopolymer keratoprostheses, noninvasive transscleral glaucoma surgery, retinal imaging and photodisruption, presbyopia surgery, and anterior lens capsulorrhexis.

CONCLUSIONS

Advances in ultra-fast laser technology continue to improve the surgical safety, efficiency, speed, and versatility of FS lasers in ophthalmology.

Femtosecond laser-assisted corneal surgery

PURPOSE OF REVIEW

The femtosecond laser has potentially improved the safety and precision of creating corneal flaps in laser in situ keratomileusis (LASIK). This review focuses on recent advances in applying femtosecond laser technology to other corneal procedures.

RECENT FINDINGS

The femtosecond laser is capable of cutting tissue at various depths and patterns with minimal collateral tissue injury. The laser can now be used to perform corneal pockets for ring segments, arcuate wedge-shaped resection in correction of high astigmatism, lamellar dissections in anterior lamellar keratoplasty, donor tissue preparation in Descemet's stripping endothelial keratoplasty, and shaped full-thickness keratoplasty.

SUMMARY

Femtosecond laser-assisted corneal surgery may provide a more precise and safer approach to corneal surgery.