The management of post-keratoplasty astigmatism by post-operative adjustment of a single continuous suture

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.

"Harmonization" of donor and recipient tomography in corneal transplantation

The applicability of donor and recipient tissue matching in corneal transplantation ("harmonization") to reduce residual astigmatism after keratoplasty was simulated using Matlab software. The height profile of the donor and recipient corneas was measured using the anterior segment optical coherence tomography (AS-OCT) Casia 2. After best fit of the donor button in the recipient bed the mean height difference as the mismatch, which had to be minimized, was derived from the height profile of the donor and recipient corneal front and back surfaces. The donor button was rotated in the recipient bed to extract the best fit situation where the mean height difference was minimized. After successful simulation, the procedure will be transferred to real measurement data.

Topography-guided customized laser-assisted subepithelial keratectomy for the treatment of postkeratoplasty astigmatism

PURPOSE

To assess topography-assisted corneal wavefront excimer laser surface ablation for the correction of ametropia and irregular astigmatism after keratoplasty.

SETTING

Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

METHODS

In this pilot study, 15 patients (16 eyes) who were intolerant of spectacle and contact lens correction due to astigmatic anisometropia after keratoplasty (15 penetrating and 1 lamellar) had topography-assisted customized excimer laser treatments. Corneal topographic data using a Keratron Scout, Placido disk system allowed for preoperative analysis of wavefront anomalies of the anterior corneal surface from which a customized excimer laser correction of both lower-order aberrations (LOAs) and higher-order aberrations (HOAs) was prepared (ORK software) for treatment with a Schwind Esiris flying-spot laser. All eyes had laser-assisted subepithelial keratectomy (LASEK) using 15% alcohol with a 20-second to 30-second application. Four eyes received an application of mitomycin-C (MMC) 0.2 mg/mL for 1 minute after stromal ablation.

RESULTS

The mean preoperative spherical equivalent (SE) was -3.50 diopters (D) +/- 3.97 (SD) (range +1.625 to -9.25 D). The preoperative cylindrical error was -7.2 D (range -2.75 to -13.5 D). The programmed laser correction was -3.14 D (range +1.62 to -9 D) with a maximum attempted cylindrical correction of -7 D. Adherent LASEK epithelial flaps along suture lines and the graft-host junction were noted in 9 eyes (56%), although it was possible to obtain and replace a partial flap. A follow-up of 18 months was achieved in all eyes. At the final follow-up visit, the mean postoperative SE was -1.08 +/- 1.85 D (range +3 to -4.78 D) (P<.01, F<.01). Ten eyes (62.5%) were within +/-1 D of the intended correction. The mean postoperative cylindrical error was -2.72 D (range -0.5 to -6.5 D) (P<.001), with vector analysis demonstrating a mean 6.23 D correction. Analysis of HOAs using a 6.0 mm pupil size demonstrated a significant reduction of higher-order root mean square (RMS) (P<.002), trefoil (P<.005), and 4th-order spherical aberration (P<.02) at 18 months compared with preoperative values. Uncorrected visual acuity improved in all eyes (P<.0001). Best spectacle-corrected visual acuity was unchanged or improved in 13 eyes (81%) and worse in 2 eyes by 1 line; 1 eye lost 3 lines due to an increase in preexisting cataract. In eyes that did not receive MMC, corneal haze (grade II to IV) was encountered in 3 eyes (27%). One eye required phototherapeutic keratectomy with MMC application at 12 months. Of the 4 eyes treated with MMC, 1 had trace haze and 3 had no detectable haze. There were no reported cases of epithelial instability, ectasia, or graft rejection.

CONCLUSIONS

Topography-assisted customized LASEK was effective in the correction of postkeratoplasty astigmatism. A significant improvement of both LOAs and HOAs was obtained with good refractive stability for over 18 months. Iatrogenic haze typically occurred but appeared to be minimized with adjunctive use of intraoperative MMC.

Laser in situ keratomileusis to correct post-keratoplasty astigmatism; 1-step versus 2-step procedure

PURPOSE

To investigate the correction of post-penetrating keratoplasty (PKP) astigmatism using laser in situ keratomileusis (LASIK). Visual and refractive outcomes were evaluated after LASIK was performed in 1 step (lamellar cut and ablation in 1 procedure) or 2 steps (lamellar cut then ablation in 2 successive procedures).

SETTING

Department of Cornea and Refractive Surgery, Vissum-Instituto Oftalmológico de Alicante, University of Miguel Hernández, Alicante, Spain.

METHODS

In this prospective observational study, 22 consecutive eyes were divided into 2 groups depending on the LASIK procedure performed to correct post-PKP astigmatism. Group 1 (1-step LASIK) included 11 eyes and Group 2 (2-step LASIK), 11 eyes. The patients were followed for 6 months.

RESULTS

A statistically significant improvement was obtained in Group 2 with a mean vector analysis result of the cylinder of -4.37 diopters (D) +/- 1.79 (SD) (P = .018). In Group 1, the mean astigmatism correction was 2.38 +/- 1.71 D. The number of reoperations and residual refractive defects were significantly better in Group 2.

CONCLUSION

The 2-step technique improved the accuracy of excimer laser correction of post-PKP astigmatism.

Keratometric astigmatism after suture removal in penetrating keratoplasty: double running versus single running suture techniques

BACKGROUND AND OBJECTIVE

To compare astigmatism after suture removal in a retrospective sequential series of patients who had penetrating keratoplasty with either a double running suture technique or an adjustable single running suture technique. During the first year postkeratoplasty, when sutures were in place, the latter technique had produced less astigmatism.

MATERIALS AND METHODS

Keratometry and keratometric astigmatism were measured before and after suture removal. We compared these variables in 30 grafts with the double running suture technique to the same variables in 24 grafts with the single running suture technique.

RESULTS

The final portion of the double running suture was removed 408 +/- 177 (mean +/- SD) days after keratoplasty, whereas the single running suture was removed 611 +/- 224 days after keratoplasty (P<0.001). After suture removal, there was no difference between the double running and single running groups in either mean keratometry [46.5 +/- 1.8 diopters (D) versus 45.6 +/- 2.0 D, P=0.09, minimum detectable difference (MDD)=1.5D] or mean astigmatism (4.6 +/- 2.7 D versus 5.2 +/- 3.2D, P=0.72, MDD=2.3).

CONCLUSION

In this consecutive series of corneal transplants performed by one surgeon, the results suggest no difference in astigmatism between the two suturing techniques after all sutures have been removed.

Laser in-situ keratomileusis after penetrating keratoplasty

Laser in situ keratomileusis (LASIK) after penetrating keratoplasty has been used more commonly for the correction of myopia or myopic astigmatism and less so for hypermetropia or hyperopic astigmatism. The primary goal after LASIK in such cases is resolution of sufficient myopia and astigmatism to allow spectacle correction of the residual refractive error and decrease anisometropia. All sutures should be removed prior to LASIK and the interval between penetrating keratoplasty and LASIK should be a minimum of 1 year. Preoperative evaluation includes refraction, slit-lamp biomicroscopy, corneal topography, and specular microscopy. The technique of LASIK surgery after penetrating keratoplasty is similar to the standard procedure. However, many variations have been described. These include maneuvers during surgery such as augmentation with arcuate cuts on the stromal bed and topographically guided LASIK. Other variations are relaxing incisions followed by LASIK surgery and sequential treatment by LASIK, that is, raising of the flap as a first stage procedure followed by ablation if required, 4 to 6 weeks later after relifting the flap in the second stage. Improvement in both uncorrected visual acuity and spectacle-corrected visual acuity, as well as a decrease in spherical equivalent, cylinder, and anisometropia, has been reported in various studies. All grafts were clear and no occurrence of wound dehiscence has been reported. Intraoperative complications include hemorrhage, microkeratome failure, flap buttonhole, dislocation, and perforation. Postoperative complications include undercorrection, decentered ablation, and regression. Re-enhancements after LASIK following keratoplasty are possible with acceptable visual outcome.

Two-stage Laser in situ Keratomileusis to Correct Refractive Errors After Penetrating Keratoplasty

PURPOSE

To evaluate the effect of a two-stage laser in situ keratomileusis (LASIK) procedure on eyes with high astigmatism and/or anisometropia after penetrating keratoplasty.

METHODS

Eleven postoperative penetrating keratoplasty eyes were included in a prospective, non-controlled study. All patients had at least 4.00 D of astigmatism and/or at least 3.00 D of anisometropia and were spectacle and contact lens intolerant. Two-stage LASIK was performed; in the first stage a hinged corneal flap 160 microm in thickness and 9 mm in diameter was created. After stabilization of corneal shape (1 to 3 months after keratotomy), the corneal flap was lifted and laser refractive treatment (second stage) was performed.

RESULTS

After the first stage, a statistically significant reduction in refractive astigmatism (P<.01) was recorded. In all eyes but one, best spectacle-corrected visual acuity was maintained or improved after the procedure. Three months after the second stage, refractive astigmatism in 8 of 11 eyes (73%) was within +/- 1.00 D, and spherical equivalent refraction in 9 of 11 eyes (82%) was within +/- 1.00 D of intended correction. Preoperative irregular astigmatism persisted in three patients (3 eyes) who could not be corrected within +/- 1.00 D of refractive astigmatism and/or +/- 1.00 D of intended spherical equivalent refraction. In one eye, an interface infiltrate developed shortly after creation of the flap, and resulted in limited melting.

CONCLUSIONS

A two-stage LASIK procedure improved visual acuity and refraction in postoperative penetrating keratoplasty eyes with high astigmatism and/or anisometropia. Complications were uncommon but can lead to loss of vision.

New techniques in lamellar keratoplasty

In the past years, several lamellar keratoplasty surgical techniques have been developed, modified or improved in the past years, including microkeratome assisted anterior and posterior lamellar keratoplasty, anterior lamellar keratoplasty using air-dissection or visco-dissection, sutureless posterior lamellar keratoplasty, LASIK for postkeratoplasty astigmatism, and excimer laser assisted keratophakia for keratoconus or to manage complications after LASIK. These procedures may continue to gain interest as alternative procedures for a penetrating keratoplasty in the treatment of various corneal disorders.

Effect of hinged lamellar keratotomy on postkeratoplasty eyes

PURPOSE

To evaluate the effect of a hinged lamellar keratotomy on refraction, vision, and corneal topography of postkeratoplasty eyes with high-degree astigmatism.

DESIGN

Noncomparative, interventional case series.

PARTICIPANTS

A hinged lamellar keratotomy was performed on nine eyes of nine patients at least 9 months after penetrating keratoplasty and with high-degree astigmatism. All patients were spectacle and contact lens intolerant.

INTERVENTION

A superiorly hinged lamellar keratotomy (corneal flap), 160 microm in thickness and 9 mm in diameter, was created on all eyes included in this study. Each patient was examined 1 day, 1 month, and 3 months after surgery.

MAIN OUTCOME MEASURES

Uncorrected visual acuity, best spectacle-corrected visual acuity, refraction, computerized analysis of corneal topography.

RESULTS

At each postoperative examination time, there was a significant reduction in both average spherical equivalent (P < 0.05) and average absolute value of astigmatism (P < 0.01) over mean preoperative values. The major changes were seen as early as 1 day after surgery, but both progression and regression of the effect were documented at later postoperative examinations. In all patients best spectacle-corrected acuity was maintained or improved after the procedure. Postoperatively, four patients could be successfully corrected either with spectacles (n = 2) or with gas-permeable contact lenses (n = 2). There were no surgical flap or corneal graft complications.

CONCLUSIONS

Hinged lamellar keratotomy improves vision and refraction of postkeratoplasty eyes with high-degree astigmatism. In some cases it may be so effective as to make planned excimer laser treatment unnecessary.

11-0 Mersilene alone as a single running suture in corneal grafts

PURPOSE

To study the safety and long-term stability of 11-0 Mersilene when used alone as a single running suture in corneal grafts.

METHODS

Seventeen eyes on which corneal transplants were performed with 11-0 Mersilene alone as a single running suture between October 1992 and April 1998 were entered into this study. Post-operative data were collected retrospectively on a standardised form. Mean age of patients at the time of surgery was 49.7 years. Pre-operative diagnoses were keratoconus (8 eyes), Fuchs' corneal dystrophy (6 eyes), megalocornea (1 eye), bullous keratopathy (1 eye) and irregular astigmatism following penetrating corneal injury (1 eye). Mean follow-up was 54.1 months, and ranged between 24 and 91 months.

RESULTS

Fourteen eyes (82%) achieved visual acuities of 6/18 or better. Post-keratoplasty astigmatism was < or = 5D in 14 eyes (82%). Sutures were left intact in 9 eyes for a mean period of 51.1 months (24-91 months). Complications included wound leak (3 cases), elevated edge (1 case), high intraocular pressure (1 case), sterile infiltrates (1 case) and early rejection (1 case).

CONCLUSION

11-0 Mersilene alone can be effectively used as a single running suture in corneal grafts. These sutures can safely be left intact for a long period due to Mersilene's non-biodegradable nature.

Endokeratoplasty as an alternative to penetrating keratoplasty for the surgical treatment of diseased endothelium: initial results

PURPOSE

To test the feasibility of a new surgical technique aimed at replacing diseased corneal endothelium while minimizing visual recovery time.

DESIGN

Noncomparative, prospective, clinic-based, interventional case series.

PARTICIPANTS

A total of seven patients with aphakic bullous keratopathy (n = 2), pseudophakic bullous keratopathy (n = 4), or Fuchs' corneal dystrophy (n = 1) participated.

INTERVENTION

All patients underwent a surgical procedure including removal of the epithelium, creation of a 9.5-mm corneal flap, substitution of an underlying 6.5-mm button of deep stroma and endothelium with a 7.0-mm donor button, and suturing of the flap back into position using a 10-0 running nylon suture. In the two most recently operated patients, anterior lamella, 160 microm in thickness, was removed from the donor button before transplantation.

MAIN OUTCOME MEASURES

Visual acuity, refraction, keratometry, corneal topography.

RESULTS

All corneas were clear, and the surface reepithelialized within 4 weeks after surgery. Regular astigmatism of less than 4 diopters was recorded in all cases as early as 4 weeks after surgery. Epithelial interface ingrowth with extensive melting of the corneal flap was observed in one patient 3 months after surgery and was managed by removal of the flap and resuturing of the donor button.

CONCLUSIONS

Endokeratoplasty represents a promising alternative to conventional penetrating keratoplasty for patients with diseased corneal endothelium.

Combined interrupted and continuous versus single continuous adjustable suturing in penetrating keratoplasty: a prospective, randomized study of induced astigmatism during the first postoperative year

OBJECTIVE

To compare postoperative astigmatism induced by two different suturing techniques in penetrating keratoplasty (PKP).

DESIGN

A monocenter, prospective, randomized clinical trial with a longitudinal 1-year follow-up.

PARTICIPANTS

A total of 95 eyes undergoing PKP were randomized into 2 groups. Of these, 51 eyes were allocated to the combined interrupted and continuous suturing group (ICS) and 44 eyes to the single continuous adjustable suturing (SCAS) group.

INTERVENTION

In the ICS group, suturing was with a combination of 12 interrupted 10-0 nylon and 1 continuous 11-0 nylon sutures. Eyes in the SCAS group had been sutured with a single running 24-bite 10-0 nylon. Selective suture removal started no earlier than 10 weeks after surgery; suture adjustment could start as soon as possible after surgery.

MAIN OUTCOME MEASURES

Astigmatism was measured by topography, keratometry, and refraction at 3-, 6-, 9-, and 12-month postoperative intervals.

RESULTS

The difference in mean time of suture manipulation between groups was significant (P = 0.0001), with the SCAS starting earlier. A significant decrease in astigmatism occurred by either interrupted suture removal (6.69 +/- 3.11 diopter [D] before to 4.76 +/- 2.99 D after, P = 0.0002) or suture adjustment (7.18 +/- 3.12 D before to 4.46 +/- 3.24 D after, P = 0.0001). However, the net astigmatic reduction in the SCAS group was not significantly greater (P = 0.250) than in the ICS group. Vector change was 7.40 +/- 4.17 D and 6.28 +/- 4.14 D for SCAS and ICS, respectively (P = 0.13). At no interval (3, 6, 9, or 12 months) was there significant difference in astigmatism between the two groups. Refractive astigmatism (cyl, D) at 1 year was 2.66 +/- 1.70 for the ICS and 3.12 +/- 2.62 for the SCAS, but there was no significant treatment effect (P = 0.945). Furthermore, 66% of the ICS eyes and 58% of the SCAS eyes (P = 0.295) were within the astigmatic target of the study (<3.5 D).

CONCLUSIONS

Postkeratoplasty astigmatism can be decreased similarly with either adjustment of a single running suture or selective removal of interrupted sutures. No advantage of the SCAS over ICS in terms of fewer manipulations or less astigmatism was seen as suggested previously.

Different suturing techniques variously affect the regularity of postkeratoplasty astigmatism

OBJECTIVE

This study aimed to determine the effect of various suturing techniques on the regularity of postkeratoplasty astigmatism.

DESIGN

A prospective clinical trial.

PARTICIPANTS

Sixty-two consecutive patients undergoing penetrating keratoplasty by the same surgeon (MB) participated.

INTERVENTION

Each patient was assigned to one of four groups according to the suturing technique used (a = 16 interrupted 10-0 nylon sutures; b = 2 running 10-0 nylon sutures, each with 8 bites; c = 2 running 10-0 nylon sutures, each with 12 bites; d = 2 running 10-0 nylon sutures, each with 16 bites). This was the only parameter permitted to be changed in the standard keratoplasty procedure used for all cases. Corneal topography was performed 1, 3, and 6 months after surgery. The astigmatic patterns seen on the corneal maps then were classified into regular (symmetric or asymmetric bowtie patterns) or irregular (distorted bowtie, multiaxial, or other patterns).

MAIN OUTCOME MEASURES

Regularity of postkeratoplasty corneal astigmatism was measured.

RESULTS

At all postoperative examination times, the percentage of irregular astigmatic patterns was highest in group a and lowest in group d (chi-square test: P < 0.005). Groups b and c showed intermediate values. The entity of the astigmatic error as measured by the simulated K-readings of the topographic maps did not differ significantly in the four groups.

CONCLUSIONS

A suturing technique using 2 running sutures with 16 bites each can minimize irregular postkeratoplasty astigmatism as long as sutures are in place, when compared with interrupted sutures or double-running sutures of less than 16 bites.

Trabeculectomy augmented with mitomycin C application under the scleral flap

AIM

The authors investigated the safety and intraocular pressure (IOP) lowering effectiveness of trabeculectomy augmented with mitomycin C application beneath the scleral flap, and assessed the influence of preoperative risk factors on the surgical outcome.

METHODS

A retrospective study of 72 consecutive high risk eyes undergoing trabeculectomy with adjunctive mitomycin C (0.2 mg/ml) applied under the scleral flap for 5 minutes was performed. Each eye was ascribed a score based on the number of preoperative risk factors, and categorised into one of three risk factor groups. Success was described as unqualified where IOP was < or = 21 mm Hg without medication and qualified where antiglaucomatous therapy was required to maintain it at such a level. A life table analysis of IOP control was calculated.

RESULTS

The mean IOP (SD) fell from a preoperative level of 28.4 (6.9) to a level of 16.63 (8.06) mm Hg at the last follow up (paired Student's t test: p < 0.0001). Fifty two eyes (72%) were classed as unqualified successes. The survival rates did not differ significantly between different risk factor groups (log rank test: chi 2 = 0.967, p > 0.1). The incidence of postoperative complications compared favourably with reports of mitomycin C application between Tenon's capsule and the undissected scleral bed.

CONCLUSION

The results illustrate that mitomycin C applied beneath the scleral flap during trabeculectomy in high risk eyes is associated with a success rate comparable to other modes of application. The incidence of potentially serious complications such as conjunctival wound leak and prolonged hypotony was lower than previously published data reporting sub-Tenon's administration of mitomycin C. The number and nature of preoperative risk factors do not appear to influence the surgical outcome. A possible mechanism of action is proposed.

Epithelial downgrowth following penetrating keratoplasty with a running adjustable suture

A 78-year-old female patient who had a third penetrating keratoplasty for aphakic bullous keratopathy and iris fixation of a posterior chamber intraocular lens using a single, 10-0 nylon running suture technique developed a suture track leak postoperatively. Attempts to ease the tension on the suture track reduced the astigmatism and stopped the leak temporarily. Eighteen months after the procedure, epithelial downgrowth was noted on the corneal graft on both sides of the leak site and intraocular pressure was elevated. A fourth penetrating keratoplasty combined with a trabeculectomy was performed. To our knowledge, this is the first report of epithelial downgrowth associated with suture adjustment following the single, continuous suture technique.

Long-term follow-up of a single continuous adjustable suture in penetrating keratoplasty

Penetrating keratoplasty was performed on 30 patients using a single adjustable continuous 10/0 nylon suture. Seventeen patients had astigmatism of 4.00 dioptre cylinders (DC) or more and were adjusted. The latest adjustment was at 32 weeks. Following adjustment there was a significant reduction in median post-keratoplasty astigmatism from 6.00 DC to 2.50 DC (p < 0.001). Thirteen patients, with astigmatism of 4.00 DC or less, were not adjusted. Median astigmatism for the non-adjusted group was 3.00 DC and for the entire group was 2.88 DC. Long-term refraction and suture status were monitored with time. Mean follow-up was 112 weeks (range 53-170 weeks). Over the study period the entire group showed significant 'long-term astigmatic drift' (LTAD), from 2.88 DC to 3.25 DC (median drift, 1.25 DC; range, 0.00-5.50 DC) (p < 0.001). Suture adjustment and suture removal showed no significant effect on LTAD. With suture removal between 32 and 84 weeks median LTAD was 1.50 DC. For suture removal after 84 weeks, median LTAD was also 1.50 DC, but the range of LTAD was 1.50 DC, compared with a larger range of 5.00 DC in the earlier suture removal group. The technique of single continuous adjustable sutures for penetrating keratoplasty is safe, effective in reducing astigmatism, but may need modification to further enhance long-term refractive stability.