Standardized arcuate keratotomy for postkeratoplasty astigmatism

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.

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.].

Circular Keratotomy Combined With Wedge Resection in the Management of High Astigmatism After Penetrating Keratoplasty

OBJECTIVE

To evaluate the effectiveness of circular keratotomy combined with wedge resection for the management of high astigmatism after penetrating keratoplasty (PK).

METHODS

The study included seven eyes of seven patients with previous PK who underwent circular keratotomy combined with wedge resection. The uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), spherical equivalent (SE) refraction, and keratometric powers obtained by corneal topography were evaluated. The power vector method was used to analyze the astigmatic change postoperatively.

RESULTS

The mean follow-up period was 18.42±8.56 months (range 12-33 months). Uncorrected visual acuity, BCVA, and SE were improved in all eyes postoperatively. The mean preoperative astigmatism reduced from 15.11±5.48 D (range, 10.0-24.4 D) to 4.98±3.01 D (range, 2.2-9.6 D), postoperatively. According to the vector analysis, the overall mean surgically induced astigmatism at last visit was 12.87±6.20 D. The most common complication was the loosening of sutures occurred in five eyes within 2 months.

CONCLUSIONS

Circular keratotomy combined with corneal wedge resection is a favorable option for the management of high astigmatism after PK.

Effects of astigmatic keratotomy combined with scleral tunnel incisions for the treatment of high astigmatism after penetrating keratoplasty

The present study aimed to evaluate the efficacy, predictability and safety of astigmatic keratotomy (AK) combined with scleral tunnel incisions in the treatment of high astigmatism after penetrating keratoplasty (PKP). Paired AK combined with scleral tunnel incisions was performed at the steep astigmatic meridian in 8 eyes of 8 patients with high keratometric astigmatism [>5.0 diopters (D)] after PKP. Pre- and post-operative parameters, including uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction and keratometric astigmatism were evaluated. The Alpins method for vector analysis was used to evaluate the changes in keratometric astigmatism. The results indicated a statistically significant reduction in the mean keratometric astigmatism from 8.16±3.02 D pre-operatively to 2.28±1.07 D at 3 months postoperatively. The mean UCVA improved from 0.95±0.24 logarithm of the minimum angle of resolution (logMAR) pre-operatively to 0.61±0.17 logMAR at 3 months postoperatively (P<0.05). The mean BCVA improved from 0.41±0.18 logMAR pre-operatively to 0.26±0.12 logMAR at 3 months postoperatively (P>0.05). Between 3 and 6 months after the surgery, the keratometric astigmatism remained stable. Alpins vector analysis demonstrated the relative predictability of this combined surgical treatment. The surgically induced astigmatism was significantly correlated with the target induced astigmatism (r=0.76, P<0.05). None of the patients had any severe complications. The present study indicated that AK combined with scleral tunnel incisions is an effective, relatively predictable and safe treatment for high astigmatism after PKP.

Vector analysis of femtosecond laser-assisted astigmatic keratotomy after deep anterior lamellar keratoplasty and penetrating keratoplasty

PURPOSE

To compare the refractive and keratometric changes induced by femtosecond laser astigmatic keratotomy (AK) for suture-out post-keratoplasty astigmatism in deep anterior lamellar keratoplasty (group I) and penetrating keratoplasty (group II).

SETTING

Dhahran Eye Specialist Hospital, Dhahran, Saudi Arabia.

DESIGN

Retrospective, comparative, interventional study.

METHODS

This study comprised 15 eyes in group I and 35 eyes in group II. All eyes underwent femtosecond AK for suture-out post-keratoplasty astigmatism. The refractive and keratometric measurements were evaluated before and 6 months after AK. The Alpins method for vector analysis was used to evaluate the keratometric changes induced by AK.

RESULTS

The astigmatic correction was 99 and 110% in group I and group II, respectively (p = 0.743) and the success of AK was 43 and 51% in group I and group II (p = 0.966). There was a trend in the magnitude of error toward overcorrection with increased surgically induced astigmatism (r = 0.80 with p < 0.001 in group I and r = 0.70 with p < 0.001 in group II). There was no systemic misalignment in either group. The safety indices were 1.50 (0.19-26.67) and 1.27 (0.12-13.33) in group I and group II, respectively (p = 0.325). The efficacy indices were 1.00 (0.05-24.00) and 0.31 (0.04-2.50) in group I and group II, respectively (p = 0.001).

CONCLUSIONS

Femtosecond laser AK has similar safety for correcting suture-out post-DALK and PKP astigmatism; however, it is more effective for DALK. There is a positive correlation between surgically induced astigmatism and magnitude of error.

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.

Office-based Relaxing Incision Procedure for Correction of Astigmatism after Deep Anterior Lamellar Keratoplasty

Purpose:

To report the outcomes of a simple and effective office-based procedure for the correction of astigmatism after deep anterior lamellar keratoplasty (DALK).

Methods:

This study enrolled 24 consecutive keratoconic eyes that developed an intolerable amount of graft astigmatism after DALK. The location and extension of steep semi-meridians were determined using corneal topography. Office-based relaxing incision procedures were performed at the slit-lamp biomicroscope using a 27-gauge needle. Relaxing incisions were made at the donor-recipient interface on one side of the steepest meridian with an arc length of 45° to 60° and an initial depth of approximately 70–80% of the corneal thickness. Topography was performed after 30–40 minutes and the initial incision was enhanced in depth and length. If an acceptable amount of astigmatism was not achieved, another incision was created at the opposite semi-meridian during the same session.

Results:

Mean follow-up period was 13.1 ± 7.4 months. Mean preoperative best spectacle corrected visual acuity was 0.26 ± 0.14 logMAR, increasing to 0.22 ± 0.09 logMAR after the procedure (P = 0.20). Mean spherical equivalent refractive error increased from − 4.64 ± 3.06 diopters (D) preoperatively to −6.06 ± 3.15 D postoperatively (P = 0.01). Mean keratometric astigmatism was reduced by 2.95 ± 3.43 D and 5.16 ± 2.97 D measured using subtraction and vector analysis methods, respectively (P < 0.001). Microperforation occurred in one eye, which spontaneously improved with no sequelae.

Conclusion:

Office-based relaxing incision is a safe and effective procedure for the treatment of corneal graft astigmatism after DALK. This approach effectively decreases the need for the more costly alternative in the operating room.

Femtosecond astigmatic keratotomy for postkeratoplasty astigmatism

PURPOSE

To evaluate the initial outcomes of femtosecond laser arcuate keratotomies (AK) to correct high astigmatism after keratoplasty.

METHODS

This retrospective non-comparative interventional study included 52 consecutive patients (52 eyes) who underwent Intralase-enabled arcuate keratotomies. Changes in uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BCVA), mean refractive and keratometric astigmatism, preoperative and postoperative manifest refraction and complications were the main outcome measures.

RESULTS

The mean follow-up period was 13.77 ± 4.17 months. Mean BCVA and UCVA improved statistically significantly from 0.30 ± 0.18 LogMAR and 0.90 ± 0.43 LogMAR preoperatively to 0.20 ± 0.14 and 0.60 ± 0.39 postoperatively respectively (P < 0.05, all comparisons). Mean subjective cylinder decreased statistically significantly from 7.15 ± 1.32 D preoperatively to 5.19 ± 2.25 D at the last postoperative visit (P = 0.0002). Two eyes (4%) lost one line or more of BCVA. Three patients (5.8%) had corneal perforation and only one eye required resuturing of the AK wound. Twelve patients (23%) were overcorrected.

CONCLUSIONS

AK performed with the femtosecond laser was relatively easy to perform, safe, and effective for treating post-keratoplasty astigmatism. There was a significant improvement in UCVA and BCVA with a very low rate of complications. A larger series is required to refine the nomogram to achieve a greater reduction in cylinder.

Long-term follow-up of astigmatic keratotomy for corneal astigmatism after penetrating keratoplasty

PURPOSE

To report the long-term stability of paired arcuate corneal keratotomies (AKs) in patients with high regular postpenetrating keratoplasty astigmatism.

METHODS

Retrospective chart review of best-corrected visual acuity, refraction and keratometric values of 41 eyes with AK between 2003 and 2012.

RESULTS

Magnitude of median target induced astigmatism vector was 9.2 dioptres (Dpt). We reached a median magnitude of surgically induced astigmatism vector of 9.81 Dpt and a median magnitude of difference vector of 5.5 Dpt. In keratometry, we achieved a net median astigmatism reduction by 3.3 Dpt. The average correction index was 1.14, showing a slight overcorrection. Irregularity of keratometric astigmatism increased by 0.6 Dpt, and spherical equivalent changed by 1.75 Dpt. Monocular best spectacle corrected visual acuity increased from preoperatively 20/63 (0.5 logMAR) to 20/40 (0.3 logMAR) postoperatively. Median gain on the ETDRS chart was two lines. Long-term follow-up showed a median keratometric astigmatic increase by 0.3 Dpt per year.

CONCLUSION

Arcuate corneal keratotomies is a safe and effective method to reduce high regular corneal astigmatism following penetrating keratoplasty but has limited predictability. The long-term follow-up shows an increase of keratometric astigmatism by 0.3 Dpt/year, equalizing the surgical effect after 10 years.

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.

Correction ratio and vector analysis of femtosecond laser arcuate keratotomy for the correction of post-mushroom profile keratoplasty astigmatism

PURPOSE

To evaluate the refractive and keratometric effect of arcuate keratotomy using femtosecond technology in patients with high post-keratoplasty astigmatism with a mushroom profile.

SETTING

Enaim Refractive Center, Tel-Aviv, Israel.

DESIGN

Noncomparative prospective interventional case series.

METHODS

The arcuate depth incision was set to 80% of the minimal graft thickness, with a 60-degree angle. The mean diameter was 5.79 mm ± 0.32 (SD) according to the graft size. Patient evaluation included logMAR corrected distance visual acuity (CDVA), refraction, keratometry (K), and a complete eye examination.

RESULTS

Twenty-seven eyes of 27 patients after keratoplasty surgery were included. Both uncorrected distance visual acuity and logMAR CDVA improved after surgery. The preoperative mean logMAR CDVA was 0.29 ± 0.37 (SD), which improved by 1 line (to 0.19 ± 0.10; P = .01). The mean refractive astigmatism was -8.43 ± 2.80 diopters (D) (range -4.5 to -15 D), and it declined at the 3-month postsurgical follow-up to -4.31 ± 0.23 D (P < .001) and remained stable until the end of follow-up (-3.31 ± 1.39 D; P = 1.00). The K value decreased by 1.18 D (P < .001). There were no complications or adverse effects during the follow-up period.

CONCLUSIONS

Arcuate keratotomies performed with the femtosecond laser showed good results. There was a more than 50% decrease in post-mushroom profile keratoplasty astigmatism as well as stability of the results over 1 year.

FINANCIAL DISCLOSURE

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

Vector Analysis of Corneal Astigmatism After Combined Femtosecond-Assisted Phacoemulsification and Arcuate Keratotomy

PURPOSE

To evaluate the outcomes of femtosecond-assisted arcuate keratotomy combined with cataract surgery in eyes with low to moderate corneal astigmatism.

DESIGN

Retrospective, interventional case series.

METHODS

This study included patients who underwent combined femtosecond-assisted phacoemulsification and arcuate keratotomy between March 2013 and August 2013. Keratometric astigmatism was evaluated before and 2 months after the surgery. Vector analysis of the astigmatic changes was performed using the Alpins method.

RESULTS

Overall, 54 eyes of 54 patients (18 male and 36 female; mean age, 68.8 ± 11.4 years) were included. The mean preoperative (target-induced astigmatism) and postoperative astigmatism was 1.33 ± 0.57 diopters (D) and 0.87 ± 0.56 D, respectively (P < .001). The magnitude of error (difference between surgically induced and target-induced astigmatism) (-0.13 ± 0.68 D), as well as the correction index (ratio of surgically induced and target-induced astigmatism) (0.86 ± 0.52), demonstrated slight undercorrection. The angle of error was very close to 0, indicating no significant systematic error of misaligned treatment. However, the absolute angle of error showed a less favorable range (17.5 ± 19.2 degrees), suggesting variable factors such as healing or alignment at an individual level. There were no intraoperative or postoperative complications.

CONCLUSIONS

Combined phacoemulsification with arcuate keratotomy using femtosecond laser appears to be a relatively easy and safe means for management of low to moderate corneal astigmatism in cataract surgery candidates. Misalignment at an individual level can reduce its effectiveness. This issue remains to be elucidated in future studies.

The evolution of corneal and refractive surgery with the femtosecond laser

The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.

The Results of Toric Intraocular Lens Implantation in Patients With Cataract and High Astigmatism After Penetrating Keratoplasty

OBJECTIVES

To evaluate the results of toric intraocular lens (IOL) implantation in patients with cataract and postpenetrating keratoplasty astigmatism.

METHODS

Seven eyes of 7 patients with cataract and more than 3.5 diopters (D) astigmatism following penetrating keratoplasty were included in this retrospective case series study. All of the eyes underwent phacoemulsification and Acrysof toric IOL (t5-t9) implantation at least 6 months later than the complete suture removal. Corrected visual acuity (CVA), manifest astigmatism, the keratometry measurements, and complications were assessed.

RESULTS

The mean preoperative CVA significantly increased (0.7±0.3 [range: 0.3-1.3] logMAR to 0.1±0.04 [range: 0.05-0.15] logMAR; P<0.05) at mean 8.71±4.11 months after the surgery. The mean preoperative corneal astigmatism and the average manifest refractive astigmatism at the last visit were 5.4±0.9 D (range: 4.25-7 D) and 1.6±0.6 D (range: 0.5-2.5 D), respectively. The mean attempted cylinder correction at spectacle plane was 4.3±0.9 D (range: 2.4-4.7 D) whereas the mean cylinder correction was 4.6±0.5 D (range: 3.9-5.9 D), showing a slightly tendency for overcorrection. All eyes (100%) were within 1 D of predicted residual astigmatism. No complication occurred during the follow-up.

CONCLUSION

Toric IOL implantation seems to be an effective, predictable, and safe procedure in patients with cataract formation and high astigmatism after penetrating keratoplasty.

Combined astigmatic keratotomy and conductive keratoplasty to correct high corneal astigmatism

PURPOSE

To determine the safety, efficacy, and predictability of combined astigmatic keratotomy (AK) and conductive keratoplasty (CK) for treating high corneal astigmatism.

SETTING

University of California-Los Angeles, Los Angeles, California, USA.

DESIGN

Retrospective case series.

METHODS

From January 1, 2004, to December 31, 2009, AK and CK were performed in eyes with corneal astigmatism of 5.0 diopters (D) or more after keratoplasty or trauma. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE), defocus equivalent, mean astigmatism, efficacy index, and complications were evaluated.

RESULTS

In 11 eyes of 11 patients, the mean UDVA improved from 1.54 logMAR ± 0.50 (SD) preoperatively to 0.69 ± 0.62 logMAR 3 months postoperatively (P < .001) and the mean CDVA from 0.55 ± 0.62 logMAR to 0.12 ± 0.11 logMAR (P = .028). The mean SE and mean defocus equivalent decreased from -1.25 ± 5.06 D to 3.13 ± 3.06 D (P = .15) and from 7.98 ± 4.41 D to 6.97 ± 3.73 D (P = .45), respectively; these changes were not statistically significant. The mean absolute astigmatism decreased from 10.25 ± 4.71 D to 4.31 ± 2.34 D (P < .001). The mean absolute orthogonal and mean oblique astigmatism showed a statistically significant decrease. The efficacy index was 0.82. One case of wound gape after AK required suturing. No infectious keratitis, corneal perforation, or graft rejection occurred.

CONCLUSIONS

Results indicate that combined AK and CK is safe and effective for correcting high corneal astigmatism after surgery or trauma.

Management of extreme ametropia after penetrating keratoplasty: a series of surgical procedures for high myopia and astigmatism

A series of surgical interventions – relaxing corneal incisions, intraocular lens, and intrastromal rings – were used to correct a case of extreme ametropia in a thin cornea after a penetrating keratoplasty in an 18-year-old patient who presented with a −10.25 −8.50 × 120 preoperative refraction and 20/200 best-corrected visual acuity (BCVA). After a series of surgical procedures, the patient's BCVA in his left eye improved to 20/30 with +0.50 −1.00 × 170, the slit lamp examination showed no significant findings, and the patient's visual complaints disappeared. At the 1-year follow-up, the BCVA was 20/25, without visual complaints. The process of individualizing the surgical procedure in the present case was employed in an outcome-based approach, that is, the next surgical procedure was defined after the surgery and postoperative evaluation. The patient did not present complications during the follow-up period of 2.5 years.

Results of toric intraocular lenses for post-penetrating keratoplasty astigmatism

PURPOSE

Evaluate the usefulness of toric intraocular lens (IOL) implantation during cataract surgery in patients after penetrating keratoplasty (PKP).

DESIGN

Retrospective case review.

PARTICIPANTS

A total of 21 eyes of 16 patients with prior PKP and moderate to high regular astigmatism after full suture removal underwent phacoemulsification and implantation of a single-piece acrylic toric IOL (SN6AT series; Alcon, Fort Worth, TX).

METHODS

Patients underwent comprehensive examinations at standard intervals, including visual acuity, manifest refraction, and corneal topography.

MAIN OUTCOME MEASURES

Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) expressed as the logarithm of the minimum angle of resolution (logMAR) and manifest refraction astigmatism.

RESULTS

From preoperatively to the last visit (mean, 14.7 ± standard deviation 12.8 months), the 21 eyes had significant improvement in UDVA (logMAR, 0.90 ± 0.48 to 0.23 ± 0.25; P = 0.0001) and CDVA (logMAR, 0.31 ± 0.14 to 0.08 ± 0.13; P = 0.0001). A total of 14 of 21 eyes (67%) and 17 of 21 eyes (81%) had UDVA and CDVA of ≥ 20/30, respectively. Preoperative topographic astigmatism was 4.57 ± 2.05 diopters (D). Postoperative manifest refraction astigmatism was 1.58 ± 1.25 D overall, but lower (0.75 ± 0.54 D) in the T7-T9 subgroup (excluding 1 outlier whose corneal astigmatism doubled after surgery) than in the T4-T6 subgroup (1.88 ± 1.28 D; P = 0.013). A total of 16 of all 21 eyes (76.2%) and 8 of 9 eyes (89%) in the T7-T9 subgroup were within 1 D of postoperative manifest astigmatism as predicted or better.

CONCLUSIONS

Toric IOLs placed during cataract surgery after PKP and full suture removal can reduce manifest refraction cylinder to predictably low levels with corresponding improvement in UDVA and CDVA in patients with moderate to high regular preoperative topographic astigmatism.

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

A 35-year-old man presented with bilateral high astigmatism following penetrating keratoplasties performed for advanced keratoconus. Femtosecond laser-enabled intrastromal astigmatic keratotomy was performed, resulting in a significant reduction in corneal astigmatism. At 4 months, the corneal astigmatism continued to decrease. The visual acuity, refraction, and serial corneal topographic data are presented.

Beveled femtosecond laser astigmatic keratotomy for the treatment of high astigmatism post-penetrating keratoplasty

PURPOSE

To use beveled femtosecond laser astigmatic keratotomy (FLAK) incisions to treat high astigmatism after penetrating keratoplasty.

METHODS

Paired FLAK incisions at a bevel angle of 135 degrees, 65% to 75% depth, and arc lengths of 60 to 90 degrees were performed using a femtosecond laser. One case of perpendicular FLAK was presented for comparison. Vector analysis was used to calculate the changes in astigmatism. Fourier domain optical coherence tomography was used to examine incision morphology.

RESULTS

Wound gaping requiring suturing was observed in the case of perpendicular FLAK. Six consecutive cases of beveled FLAK were analyzed. Fourier domain optical coherence tomography showed that beveled FLAK caused a mean forward shift of Bowman layer anterior to the incisions of 126 ± 38 μm, with no wound gaping. The mean magnitude of preoperative keratometric astigmatism was 9.8 ± 2.9 diopters (D), and postoperatively it was 4.5 ± 3.2 D (P < 0.05). Uncorrected visual acuity improved from 1.24 ± 0.13 logarithm of the minimum angle of resolution preoperatively to 0.76 ± 0.38 postoperatively (P < 0.05). Best spectacle-corrected visual acuity improved from 0.43 ± 0.33 logarithm of the minimum angle of resolution preoperatively to 0.27 ± 0.24 postoperatively (P = 0.22). Visual results were reduced in 2 patients by cataract progression. Between 1 and 3 months after beveled FLAK, the keratometric cylinder was stable (<1 D change) in 5 of 6 patients, and regressed in 1 patient. No complications occurred.

CONCLUSIONS

Beveled FLAK incisions at varied depth are effective in the management of postkeratoplasty astigmatism. Early postoperative changes stabilized within 1 month in most patients. Further studies are needed to assess long-term outcomes.

Femtosecond laser technology in corneal refractive surgery: a review

PURPOSE

To discuss current applications and advantages of femtosecond laser technology over traditional manual techniques and related unique complications in corneal refractive surgical procedures, including LASIK flap creation, intracorneal ring segment implantation, astigmatic keratotomy, presbyopic treatments, and intrastromal lenticule procedures.

METHODS

Literature review.

RESULTS

From its first clinical use in 2001 for LASIK flap creation, femtosecond lasers have steadily made a place as the dominant flap-making technology worldwide. Newer applications are being evaluated and are increasing in their frequency of use.

CONCLUSIONS

Femtosecond laser technology is rapidly becoming a heavily utilized tool in corneal refractive surgical procedures due to its reproducibility, safety, precision, and versatility.

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.

Paired arcuate and modified circular keratotomy in keratoconus

AIM: To reduce astigmatism, increase corneal volume and improve visual acuity.

METHODS: A retrospective, single-surgeon, single-center, clinic-based study of a surgical procedure on twenty-four eyes of fourteen patients diagnosed with stage III or stage IV keratoconus. Paired arcuate keratotomy coupled with modified circular keratotomy was performed at a single center by a single surgeon as an outpatient procedure with local anaesthetic in a minor surgery room. Modified circular keratotomy was performed 7 mm from the pupillary center with depth of incision ranging between 70% and 90% of corneal thickness. Arcuate keratotomy was performed 2.5 mm from the pupillary center with the depth of incision at 90% of corneal thickness. Angular length of the arcs ranged between 60° and 120° depending on the astigmatic power of the cornea.

RESULTS: Astigmatism decreased in 87.5% of the 24 treated eyes, increased in 8.33% and did not change in 4.17%. Corneal volume increased in 91.66% of the 24 eyes and decreased in 8.34%. Visual acuity improved in 100% of the eyes; there was a mean improvement of 59% from preoperative visual acuity, 8.34% of the treated eyes reaching a visual acuity of 1.0 (20/20) with correction. No complications occurred during or after surgery. No suturing was performed and there was no rupturing at incision sites. There was statistical significance difference between pre.sph against post.sph (P = 0.001). Also between pre.cyl against post.cyl (P = 0.005), there was no significance difference between pre.axis against post.axis (P = 0.05).

CONCLUSION: Paired arcuate keratotomy coupled with modified circular keratotomy should be considered as an intervention before performing keratoplasty.

Correlation of central and peripheral corneal thickness in healthy corneas

PURPOSE

To study the thickness profile of the normal cornea in order to establish any correlation between central and peripheral points.

METHODS

Sixty-seven eyes of 40 patients were subjected to central corneal thickness measurement (CCT) with an ultrasound pachymeter (UP) and corneal thickness mapping with the Oculus Pentacam. The corneal apex thickness (CAT), pupil centre thickness (recorded as CCT and corresponded to CCT of UP) and thickness at the thinnest location (CTL) were obtained and compared with each other. Corneal thickness data at 3 mm and 7 mm temporally, nasally, superiorly and inferiorly from the corneal apex were obtained. The mean corneal thickness values along the 2, 4, 6, 8 and 10 mm diameter concentric circles, with the CTL as the centre, were also obtained. The above data at different points were statistically correlated.

RESULTS

There was no significant difference between CCT readings measured by UP and Pentacam (P=0.721). There was high positive correlation between the CAT values and the thickness at 3 mm (R≥0.845, P<0.001) and at 7 mm points (R≥0.654, P<0.001). A gradual increase in thickness was noted from the centre to the periphery with a high positive correlation between the CTL values and the mean thickness at the circles of 2, 4, 6, 8 and 10 mm (R≥0.635, P<0.001).

CONCLUSION

The results suggest that central corneal thickness can serve as a good guide for predicting peripheral thickness. For surgical procedures specifically undertaken at mid-peripheral and peripheral zones, the actual measurements at the site of surgery may confer some advantage.

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.

Phacoemulsification and customized toric intraocular lens implantation in eyes with cataract and high astigmatism after penetrating keratoplasty

Phacoemulsification and implantation of a hydrophilic acrylic toric intraocular lens (IOL) (T-flex 623T) with customized cylindrical power was performed in 1 eye in 3 consecutive patients with cataract and high postkeratoplasty astigmatism (range 6.75 to 8.75 diopters [D]). Twelve months postoperatively, the uncorrected distance visual acuity improved from 20/200 to 20/30 in Case 1, from 20/400 to 20/40 in Case 2, and from 20/200 to 20/25 in Case 3 and the corrected distance visual acuity was 20/25 or better in all 3 eyes. The spheroequivalent was within ± 0.50 D of the intended value and the refractive astigmatism was less than 1.00 D. The corneal grafts were transparent, and the endothelial cell loss range was 6% to 12%. Rotation of the toric IOL was less than 5 degrees. The toric IOL with customized cylindrical power provided good postoperative rotational stability and very satisfactory postoperative visual recovery. This type of toric IOL is appropriate to correct high postkeratoplasty astigmatism in eyes operated on for cataract.

FINANCIAL DISCLOSURE

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

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.

Refractive surgery after corneal transplant

PURPOSE OF REVIEW

Ametropia and astigmatism following successful penetrating keratoplasty can seriously impact a patient's quality of vision. Similar limitations can result following anterior lamellar keratoplasty (ALK) and Descemet's stripping endothelial keratoplasty (DSEK). These patients often suffer from aniseikonia and can be intolerant of spectacles and contact lenses. Refractive surgery can correct both ametropia and astigmatism following corneal transplantation and improve a patient's final visual outcome. The same methods used to correct naturally occurring refractive errors are being used with increasing success in patients who have undergone corneal transplants.

RECENT FINDINGS

Many refractive options are available to treat ametropia following penetrating keratoplasty. Incisional keratotomies have been employed to treat high amounts of astigmatism. Photorefractive keratectomy (PRK) and laser in-situ keratomileusis (LASIK) are also used to treat myopia, hyperopia and astigmatism. LASIK has been shown to have an overall better outcome compared to PRK; however, the use of mitomycin-C with PRK has improved results. Phakic and pseudophakic piggyback intraocular lenses are also being used to treat high degrees of ametropia and astigmatism; however, the long-term results are somewhat limited.

SUMMARY

Refractive surgery can improve the final visual outcome of patients who have undergone successful corneal transplantation. Currently available modalities provide many options for patients who are intolerant of spectacles and contact lenses. Continued advances and research will enable surgeons to optimize visual quality in postkeratoplasty patients.

IntraLase-enabled astigmatic keratotomy for post-keratoplasty astigmatism: on-axis vector analysis

PURPOSE

To determine the refractive predictability, stability, efficacy, and complication rate of femtosecond laser-enabled astigmatic keratotomy for post-keratoplasty astigmatism.

DESIGN

A retrospective case series (pilot study).

PARTICIPANTS

Thirty-seven eyes of 34 patients.

METHODS

All eyes underwent IntraLase-enabled astigmatic keratotomy for high astigmatism (>5 diopters [D]) after penetrating keratoplasty.

MAIN OUTCOME MEASURES

Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, higher-order aberrations, and complications.

RESULTS

Mean follow-up was for 7.2 months. Uncorrected visual acuity improved from a mean of 1.08+/-0.34 logarithm of the minimum angle of resolution preoperatively to a mean of 0.80+/-0.42 postoperatively (P=0.0016). Best-corrected visual acuity improved from a mean of 0.45+/-0.27 preoperatively to 0.37+/-0.27 postoperatively (P=0.018). The defocus equivalent was significantly reduced by more than 1 D (P=0.025). The value of absolute astigmatism was reduced from 7.46+/-2.70 D preoperatively to 4.77+/-3.29 D postoperatively (P=0.0001). Higher-order aberrations were significantly increased. The efficacy index was 0.6+/-0.6. There were no cases of perforation, wound dehiscence, or infectious keratitis. Three eyes (8%) experienced an episode of graft rejection. Overcorrection occurred in 9 eyes (24%).

CONCLUSIONS

IntraLase-enabled astigmatic keratotomy is an effective treatment for high astigmatism after penetrating keratoplasty with an encouraging refractive predictability. Future studies may help refine the treatment parameters required to achieve reduction of cylinder with greater accuracy.

[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.