Corneal wavefront errors 24 months after deep lamellar endothelial keratoplasty and penetrating keratoplasty

PURPOSE

To evaluate high-order aberrations (HOA) induced by the anterior corneal surface after deep lamellar endothelial keratoplasty (DLEK) and penetrating keratoplasty (PK).

DESIGN

Prospective, randomized clinical trial.

METHODS

Twenty-eight eyes of 25 patients with corneal edema resulting from Fuchs dystrophy underwent DLEK with a 9- to 10-mm incision (n = 13) or PK with double-running sutures (n = 15) at the Cornea Service, Mayo Clinic Department of Ophthalmology, Rochester, Minnesota. The main outcome measures were HOA from the anterior corneal surface calculated from corneal topography and decomposed into Zernike polynomials to the sixth order, high- and low-contrast visual acuity (VA), and contrast sensitivity. Variables after surgery were compared with those before surgery and between treatments by using generalized estimating equation models with Bonferroni adjustment.

RESULTS

Total HOA through 24 months (0.48 +/- 0.15 microm) after DLEK was similar to total aberration before surgery (0.44 +/- 0.23 microm; P = .10). After PK, total HOA remained elevated through 24 months (1.68 +/- 0.58 microm) compared with that before surgery (0.49 +/- 0.27 microm; P < .005) and compared with that after DLEK (P < .006). At 24 months after PK, corneas with sutures removed had greater total HOAs than corneas with sutures intact (1.90 +/- 0.52 microm vs 1.18 +/- 0.33 microm; P = .001). High- and low-contrast VA and contrast sensitivity at 24 months after PK did not correlate with any HOA.

CONCLUSIONS

HOAs from the anterior corneal surface were higher after PK compared with after DLEK but did not correlate with visual function after PK.

Femtosecond laser shaped penetrating keratoplasty: one-year results utilizing a top-hat configuration

PURPOSE

To evaluate use of a femtosecond laser to create shaped corneal grafts in penetrating keratoplasty (PK) in treatment of corneal disease.

DESIGN

Prospective, nonrandomized clinical study.

METHODS

Six eyes of six patients were treated in this initial series. Two had herpetic scarring, two had pseudophakic bullous keratopathy, one had Fuchs endothelial dystrophy and one had endothelial dystrophy with a corneal scar. Preoperative best spectacle-corrected visual acuity (BSCVA) ranged from count fingers to 20/50. Donor and recipient corneas were cut in a "top-hat" shaped configuration utilizing a 15-kHz femtosecond laser.

RESULTS

All eyes were successfully treated without intraoperative complications. Mean time to complete suture removal was 7.0 +/- 1.9 months (range, 4.1 to 9.7 months). At the one-year postoperative exam, mean endothelial cell density was 2030 +/- 600 cells/mm(2) (range, 1007 to 2497 cells/mm(2)), which was comparable with cell density measured in a prior series of traditional PKs (P = .21). BSCVA ranged from 20/400 to 20/25. In two eyes, preexisting retinal conditions limited visual improvement following transplantation.

CONCLUSIONS

Use of the femtosecond laser allowed precise dissection of donor and recipient corneas even when significant opacities were present. The use of a top-hat configuration allowed for an increased area of wound healing in these eyes.

Long-term refractive results of elliptical excimer laser penetrating keratoplasty (EELPK)

PURPOSE

To assess long-term refractive and visual outcome of elliptical excimer laser penetrating keratoplasty (EELPK).

METHODS

Inclusion criteria (17 eyes): (1) Primary central elliptical excimer laser penetrating keratoplasty in phakic eyes; (2) No other simultaneous procedure except cataract surgery in 6 eyes; (3) Interrupted sutures; (4) Complete sequence of follow-ups before EELPK, with all-sutures-in, with all-sutures-out; (5) No active inflammation at the time of EELPK. Best corrected visual acuity (BCVA), refractive and keratometric astigmatism, topographic surface regularity index (SRI), surface asymmetry index (SAI) were determined in 5.9+/-3.3 years follow-up.

RESULTS

BCVA improved from 0.2 preoperatively to 0.6 after suture removal (p<0.001). After suture removal, keratometric (4.9D/5.8D, p=0.01) and refractive cylinder (2.8D/4.4D; p<0.001) increased, and SRI and SAI decreased significantly (3.0/1.0; 1.9/0.9; p=0.01) compared to all-suture-in values.

CONCLUSIONS

EELPK is effective in improving visual acuity. Despite topographic regularization, an increase of refractive more than keratometric astigmatism may occur after suture removal.

Elliptical Nonmechanical Corneal Trephination

PURPOSE

To assess intraoperative complications and long-term outcome of elliptical excimer laser trephination for penetrating keratoplasties (EELPKs) performed at the Friedrich-Alexander University of Erlangen, between 1989 and 2002.

METHODS

This was a retrospective, longitudinal, single-center, clinical, interventional case series. Forty-two eyes (14 Fuchs dystrophy, 11 corneal ulcer, 7 aphakic/pseudophakic bullous keratopathy, 9 corneal scars, 1 keratotorus) after EELPK were observed. Trephination was performed with a 193-nm Meditec excimer laser along metal masks with 0-8 orientation teeth/notches. Horizontal/vertical graft diameters ranged from 7.0/6.0 to 8.0/7.0 mm, and 12 to 24 interrupted sutures were used. Simultaneously, 11 eyes (26.2%) underwent cataract surgery, 3 (7.1%) underwent intraocular lens (IOL) exchange, and 1 (2.4%) underwent secondary IOL implantation. The main outcome measures included intraoperative complications, immune reactions, and final astigmatism/visual acuity at the end of follow-up.

RESULTS

During surgery, 4 (9.5%) recipients had iris bleedings, and 10 (23.8%) ring-shaped superficial corneal thermal donor damages were detected. One (2.4%) immunologic graft rejection was seen in Fuchs dystrophy, and 3 (7.1%) in corneal ulcers occurred during follow-up (4.7 +/- 3.2 years). At the end of follow-up, corrected visual acuity (0.1/0.4; P < 0.001) and keratometric astigmatism (2.3 D/4.7 D, P = 0.001) increased significantly.

CONCLUSIONS

In EELPK, intraoperative disadvantages, such as the need for interrupted sutures and a tendency toward higher and more irregular astigmatism, may be expected. This study does not have the power to statistically confirm the tendency of EELPK toward a lower rate of immunologic graft rejections after normal-risk keratoplasty. However, EELPK may have advantages in deep or perforated elliptically shaped corneal ulcers (such as in acanthamoeba keratitis).

Corneal Curvature after Penetrating Keratoplasty before and after Suture Removal: A Comparison between Keratoconus and Fuchs’ Dystrophy

PURPOSE

To assess the differences concerning corneal curvature and visual acuity after penetrating keratoplasty (PKP) comparing keratoconus (KC) and Fuchs' dystrophy (FUCHS).

METHODS

Inclusion criteria for this prospective, comparative, interventional study were: (1) one surgeon, (2) central round nonmechanical excimer laser PKP without previous surgery, (3) FUCHS (n = 35) or KC (n = 52), (4) standardized graft size (7.5-8.0 mm) and technique, 16-bite double running cross-stitch suture. In 69% of FUCHS, a triple procedure was performed. The main outcome measures were: keratometric astigmatism, surface regularity index, surface asymmetry index, keratometric central corneal power and best-corrected visual acuity before (1.2 +/- 0.4 years) and after suture removal (1.8 +/- 0.6 years).

RESULTS

Astigmatism did not differ significantly between KC and FUCHS (p > 0.1) before (3.3 dpt vs. 3.5 dpt median) and after suture removal (2.5 dpt vs. 3.0 dpt). Surface regularity index and surface asymmetry index were significantly higher in FUCHS than in KC (p < 0.001) at both time stages. Central power was significantly greater in KC than in FUCHS (p < 0.001) with sutures in place. Due to a significant steepening in FUCHS and flattening in KC, this difference was no longer present after suture removal. Visual acuity in KC exceeded that in FUCHS before (0.68 vs. 0.60) and even more after suture removal (0.86 vs. 0.60; p < 0.001).

CONCLUSIONS

In KC, keratometric astigmatism is not higher than in FUCHS after PKP. After suture removal, graft topography in KC and FUCHS may be expected to regularize and the excessive corneal flattening in FUCHS to normalize in the mid-term.

Comparison of complication rates and postoperative astigmatism between nylon and mersilene sutures for corneal transplants in patients with Fuchs endothelial dystrophy

PURPOSE

The purpose of this study is to evaluate corneal astigmatism and suture-related complications for transplants sutured with nylon and transplants sutured with Mersilene in primary corneal transplants for Fuchs endothelial dystrophy.

METHODS

A retrospective, observational, and comparative study between transplants sutured with either nylon 10-0 or 11-0 (n = 108) or Mersilene 11-0 (n = 58) was done. One hundred sixty-six eyes of 140 patients who received a primary penetrating keratoplasty for Fuchs endothelial dystrophy between 1995 and 2001 at the Rotterdam Eye Hospital in Netherlands were included.

RESULTS

Overall, transplant survival did not differ between groups (log-rank test; P = 0.24). During the first 2 years after transplantation, significantly lower astigmatism was seen in transplants sutured with nylon (P = 0.03). Transplants sutured with Mersilene had a significantly higher risk of surgical intervention to correct astigmatism or wound dehiscence after transplantation (hazard ratio, 2.83; 95% confidence interval, 1.34-6.01). Time to first infiltrate, metaplasia (marked scarring along the sutures), or cheesewiring was significantly less in the Mersilene group (P < 0.01). There was a tendency toward a higher risk of complications associated with loose or broken sutures in the nylon group (hazard ratio, 2.00; 95% confidence interval, 0.57-6.98), which was more pronounced after 2 years.

CONCLUSIONS

During the first years after corneal transplant surgery, Mersilene sutures are associated with a higher risk of complications and more interventions to correct suture-related problems. However, after 2 years, the grafts seem to be able to retain Mersilene sutures with less risk of suture-related complications as compared with grafts with retained nylon sutures. These favorable long-term effects of Mersilene sutures may outweigh its short-term disadvantage in patients with Fuchs endothelial dystrophy.

Changes in corneal power and refraction due to sequential suture removal following nonmechanical penetrating keratoplasty in eyes with keratoconus

PURPOSE

To assess the changes in corneal power and refraction due to sequential suture removal after penetrating keratoplasty (PK).

DESIGN

Retrospective consecutive case series.

METHODS

setting: Clinical practice. study population: We studied 67 phakic keratoconus eyes (central excimer laser trephination, primary keratoplasty, graft/recipient diameter 8.1/8.0 mm; double running suture) in this longitudinal study. main outcome measures: Zeiss keratometry (equivalent power (KEQ), astigmatism (KAST)), corneal topography (equivalent power (TEQ), astigmatism (TAST)) and subjective refractometry (spherical equivalent (SEQ), refractive cylinder (RAST)) were assessed with sutures in place (interval 1), with one suture out (interval 2), and with all sutures out (interval 3). observation procedure: Corneal power and refraction was decomposed into vector components and the changes were derived between time stages.

RESULTS

The mean follow-up period was 3.9+/-1.7 years. At interval 1, the axes of KAST/TAST/RAST were almost randomly distributed. At interval 2, the with/against the rule component of KAST/TAST/RAST decreased slightly and the oblique component increased significantly, so that the axes tended to have a preferred oblique direction. At interval 3, the with/against the rule component of KAST/TAST/RAST increased slightly and the oblique component decreased significantly, so that the with/against the rule component exceeded the oblique component by approximately 23%/28%/25%. Median KEQ/TEQ/SEQ changed by 0.64/0.62/-1.11 diopters (interval 1 to interval 2) and by -0.85/-0.90/1.56 diopters (interval 2 to interval 3).

CONCLUSIONS

As a result of removal of the first running suture, corneal astigmatism as well as the refractive cylinder tend to oblique axes. As a result of removal of the second running suture, the final corneal astigmatism and refractive cylinder tend to orientation axes with/against the rule.

Long-term changes in corneal surface configuration after penetrating keratoplasty

PURPOSE

To examine the long-term longitudinal changes in corneal surface configuration as determined by Fourier series harmonic analysis of videokeratography data and of visual acuity and refraction after penetrating keratoplasty (PK).

DESIGN

Interventional case series.

METHODS

One hundred thirty eyes of 130 consecutive patients who were scheduled for PK using 16 interrupted 10-0 nylon sutures were recruited. Spherical equivalent power, regular astigmatism component, irregular astigmatism (asymmetry and higher-order irregularity) component of the central cornea as determined by Fourier analysis of videokeragraphic data, spectacle-corrected visual acuity, and spherical equivalent were examined at 1 week, and at 1, 3, 6, 9, 12, 18, and 24 months after PK.

RESULTS

Spherical equivalent power increased considerably for up to 1 month after PK, but thereafter showed no further appreciable change up to the final follow-up at 24 months. The regular astigmatism component decreased markedly for up to 6 months after PK, while the total irregular astigmatism (sum of the asymmetry and higher-order irregularity) component decreased considerably up to approximately 3 months, and then these showed no further relevant change for up to 24 months. Spectacle-corrected visual acuity also improved markedly until approximately 3 months after PK, after which it was virtually stable. Furthermore, important correlations were found between regular and irregular astigmatism and the spectacle-corrected visual acuity.

CONCLUSIONS

Corneal surface configuration after PK appears to be stable by approximately 6 months after PK, concurrent with postkeratoplasty stabilization of visual acuity.

Spontaneous long-term changes of corneal power and astigmatism after suture removal after penetrating keratoplasty using a regression model

PURPOSE

To assess the diagnosis-based spontaneous long-term changes in corneal power and refraction with a regression model in the all-sutures-out time period following non-mechanical penetrating keratoplasty (PK).

DESIGN

Retrospective non-randomized clinical trial.

METHODS

setting: Clinical practice. study population: 147 eyes [47 Fuchs dystrophy (FD); 100 keratoconus (KC)] were studied after suture removal in this retrospective longitudinal study. main outcome measures: Zeiss keratometry [equivalent power (KEQ) and astigmatism (KAST)], corneal topography analysis [equivalent power (TEQ) and astigmatism (TAST)], and subjective refractometry [spherical equivalent (SEQ) and refractive cylinder (RAST)] were assessed in at least three up to 16 ophthalmologic examinations in the all-sutures-out time period. observation procedure: The time course of each target variable was analyzed in a longitudinal manner (time interval > or = 12 months) separately for each patient with a linear regression model.

RESULTS

Post-keratoplasty follow-up ranged from 31 months to 10.3 years. In the linear regression model, the annual change in FD/KC showed an increase/a decrease in KEQ (0.29 +/- 0.50/-0.63 +/- 0.46 diopters, P = .02) and an increase/a decrease in TEQ (0.37 +/- 0.54/-0.69 +/- 0.49 diopters, P = .04) corresponding to a decrease/an increase in SEQ (-0.31 +/- 0.47/0.63 +/- 0.43 diopters, P = .02). KAST/TAST/RAST showed a minimal annual decrease (-0.06 +/- 0.41/-0.05 +/- 0.45/-0.06 +/- 0.41 diopters) in FD but an increase in KC (0.46 +/- 0.41/0.51 +/- 0.43/0.46 +/- 0.38 diopters) (P = .05/0.06/0.12).

CONCLUSIONS

In the follow-up after post-keratoplasty suture removal, patients with FD/KC tend to develop a spontaneous myopic shift (steepening of the cornea)/hyperopic shift (flattening of the cornea). In contrast with those with FD, patients with KC should be counseled on the fact that astigmatism may increase again over time after suture removal.

Refractive outcome of single running suture adjustment in penetrating keratoplasty

PURPOSE

To evaluate the effectiveness of single running suture adjustment in reducing postoperative astigmatism and improving visual acuity in patients who have undergone penetrating keratoplasty.

METHODS

Eighteen eyes of 18 patients who underwent penetrating keratoplasty at the Department of Ophthalmology, Başkent University between May 1997 and December 2000 and who had an astigmatism over 2 diopters (D) at the fourth postoperative week were included. All eyes underwent suture adjustment at the fourth week and eight eyes with residual astigmatism above 3 D underwent a second adjustment at the eighth week. Final astigmatism and visual acuity findings were evaluated 28 weeks postoperatively.

RESULTS

The mean postoperative keratometric and refractive astigmatism were 5.76 +/- 0.88 D (range=4.50-7.76) and 5.22 +/- 0.78 D (range=4.0-7.0) at the fourth week, which were decreased to 2.82 +/- 0.99 D (range=1.25-4.62, p=0.0001) and 2.61 +/- 1.01 D (range= 1.0-4.5, p=0.0001) after suture adjustment, respectively. In eight eyes at the eighth week, a second suture adjustment reduced the average keratometric and refractive astigmatism from 3.86 +/- 0.65 D (range=2.75-4.62) and 3.81 +/- 0.44 D (range=3.25-4.50) to 2.33 +/- 0.91 D (range=0.87-3.50, p=0.012) and 2.06 +/- 0.68 D (range=1.0-2.75, p=0.011), respectively. At the 28th week, the average keratometric and refractive astigmatism levels for the entire cohort, which were 2.39 +/- 1.06 D (range=1.0-3.50) and 2.25 +/- 0.96 D (range=1.0-3.25), respectively, showed a statistically significant decrease when compared with the levels before the first suture adjustment (p=0.0001 for both data). The mean best-corrected visual acuity was 20/25 on the Snellen chart at the 28th week.

CONCLUSIONS

Postoperative adjustment of single running suture is a safe and effective way of reducing postkeratoplasty astigmatism.

Impact of graft diameter on corneal power and the regularity of postkeratoplasty astigmatism before and after suture removal

OBJECTIVE

To assess the impact of graft diameter on corneal curvature before and after removal of a double-running suture after nonmechanical penetrating keratoplasty (PK).

DESIGN

Prospective, nonrandomized, comparative (self-controlled) single-center clinical trial.

PATIENTS

Four hundred eighty-nine eyes with "two sutures in" and 308 eyes with "all sutures out" (mean age, 52+/-19 years) were included. The diagnoses were keratoconus (48%), Fuchs' and stromal dystrophies (31%), aphakic or pseudophakic bullous keratopathy (11%), and scars (10%).

INTERVENTIONS

In all eyes, a central trephination was performed (donor trephination from the epithelial side) using the 193-nm Meditec excimer laser (Carl Zeiss Meditec, Jena, Germany) along metal masks with eight "orientation teeth/notches." Diameters were 8.0 mm, 7.5 mm, and 7.0 mm with a graft oversize of 0.1 mm. In 29% of eyes, additional cataract, intraocular lens surgery, or both were performed simultaneously. In all eyes, a double-running 10-0 nylon suture was applied. Zeiss keratometry and TMS-1 topography analysis were performed before removal of the first suture (14+/-4 months) and at least 6 weeks after removal of the second suture (20+/-4 months), but before any additional surgery, such as cataract extraction or refractive keratotomies.

MAIN OUTCOME MEASURES

Topographic central corneal power (CP; keratometric diopters), keratometric astigmatism (KA), surface regularity index (SRI), and surface asymmetry index (SAI). The regularity of keratometry mires was recorded semiquantitatively from 0 = regular to 3 = not measurable (as published earlier).

RESULTS

With both sutures in, median CP in 7.0-mm (42.0 diopters [D]; P = 0.04) and in 7.5-mm grafts (42.3 D; P = 0.007) was significantly lower than in 8.0-mm grafts (43.0 D). Keratometric astigmatism did not differ between groups (3.0 D vs. 3.0 D vs. 2.7 D). The SRI (1.66 vs. 1.43 vs. 1.11) and SAI (1.55 vs. 1.24 vs. 0.85) decreased significantly with increasing diameter. The proportion of regular keratometry mires (13% vs. 17% vs. 29%) increased, and the proportion of not measurable keratometries (45% vs. 18% vs. 9%) decreased with increasing diameter. With all sutures out, CP in 7.0-mm grafts (40.4 D) was significantly smaller than in 7.5-mm (43.6 D; P = 0.04) and 8.0-mm grafts (43.3 D; P = 0.04). Again, KA did not differ between groups (3.0 D vs. 3.2 D vs. 3.0 D). The SRI (1.40 vs. 1.09 vs. 0.84) and SAI (1.24 vs. 0.83 vs. 0.62) decreased significantly with increasing diameter. The proportion of regular keratometry mires (5% vs. 31% vs. 52%) increased, and the proportion of not measurable keratometries (42% vs. 11% vs. 4%) decreased with increasing diameter.

CONCLUSIONS

After PK, a smaller graft diameter results in a flatter curvature and a higher degree of topographic irregularity, but not in higher net astigmatism. After suture removal, graft topography tends to regularize, whereas the principal differences between diameters do persist.

Deep suturing technique for penetrating keratoplasty

PURPOSE

To evaluate the effect of a new suturing technique on postkeratoplasty visual rehabilitation time and refractive error.

METHODS

Penetrating keratoplasty was performed on 17 eyes with keratoconus using a modified suturing technique. A donor button 8.0 mm in diameter was sutured into a 7.75-mm recipient bed with both deep and superficial sutures. The deep sutures consisted of either a single 16-bite 10-0 nylon running suture (n = 7) or eight interrupted 10-0 nylon cross-stitches (n = 10). These sutures were passed into the mid-stroma of the donor cornea and exited through the donor endothelium, then passed through the endothelium of the recipient cornea and exited from its mid-stroma. Thereby all parts of the deep sutures remained below the corneal surface. To further secure the surgical wound, in each case a running 16-bite 10-0 nylon superficial suture was also placed. Care was taken to maintain the bites of the superficial suture above the level of the deep sutures. The superficial suture was removed 3 months after surgery. Vision and refraction were recorded 1 day and 1 month postoperatively and 1 and 3 months after suture removal. A paired Student test was used to verify the significance of changes in visual acuity and refraction recorded at different examination times.

RESULTS

As early as 1 month after surgery, spectacle best-corrected visual acuity 20/40 or more and refractive astigmatism less than 4 diopters (D) were recorded in each eye and maintained with two exceptions at the later examination times. In two patients, postoperative astigmatism increased from 4.5 to 5 D after suture removal.

CONCLUSIONS

Deep suturing allowed quick visual rehabilitation while minimizing postkeratoplasty astigmatism in the patients with keratoconus operated on in this series.

Fourier series harmonic analysis of corneal topography following suture removal after penetrating keratoplasty

PURPOSE

To evaluate quantitatively the influence of suture removal after penetrating keratoplasty on corneal refraction including irregular astigmatism.

METHODS

Subjects were 42 eyes of 39 patients with clear corneal grafts who underwent suture removal after penetrating keratoplasty. Videokeratography data taken before and after suture removal were decomposed using Fourier harmonic analysis into spherical power, regular astigmatism, and irregular astigmatism (asymmetry and higher order irregularity).

RESULTS

On average, spherical power significantly increased after suture removal (p < 0.0001, paired t test), and regular astigmatism did not change significantly (p = 0.247). Suture removal significantly decreased asymmetry (p < 0.0001) and higher order irregularity (p < 0.0001).

CONCLUSIONS

Suture removal after penetrating keratoplasty induces myopic shift and reduction in irregular astigmatism of the cornea.

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.

Nonmechanical corneal trephination with the excimer laser improves outcome after penetrating keratoplasty

OBJECTIVE

To assess the impact of nonmechanical trephination on the outcome after penetrating keratoplasty (PK).

DESIGN

Prospective, randomized, cross-sectional, clinical, single-center study.

PATIENTS

A total of 179 eyes of 76 females and 103 males, mean age at the time of surgery 50.6 +/- 18.5 (range, 15-83) years. Inclusion criteria were (1) time interval from October 1992 to December 1997; (2) one surgeon (GOHN); (3) primary central PK; (4) Fuchs dystrophy (diameter, 7.5 mm) or keratoconus (diameter, 8.0 mm); (5) graft oversize, 0.1 mm; (6) no previous intraocular surgery; and (7) 16-bite double-running diagonal suture.

INTERVENTION

In a randomized fashion, eyes were assigned either to trephination with the 193-nm Meditec excimer laser (manually guided beam in patients, automated rotation device of artificial anterior chamber in donors) along metal masks with eight orientation teeth/notches (EXCIMER: 53 keratoconus, 35 Fuchs dystrophy; mean follow-up, 37 +/- 16 months) or with a hand-held motor trephine (Microkeratron; Geuder) (

CONTROL

53 keratoconus, 38 Fuchs dystrophy; mean follow-up, 38 +/- 14 months). Subjective refractometry (trial glasses), standard keratometry (Zeiss), and corneal topography analysis (TMS-1; Tomey) were performed before surgery, before removal of the first suture (15.2 +/- 4.2 months), and after removal of the second suture (21.4 +/- 5.6 months).

MAIN OUTCOME MEASURES

Keratometric and topographic net astigmatism as well as refractive cylinder; keratometric and topographic central power; best-corrected visual acuity (VA); surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) of the TMS-1.

RESULTS

Before suture removal, mean refractive/keratometric/topographic astigmatism did not differ significantly between EXCIMER (2.5 +/- 1.8 diopters [D]/3.4 +/- 2.8 D/4.7 +/- 3.1 D) and CONTROL groups (3.0 +/- 1.8 D/3.7 +/- 2.4 D/4.3 +/- 2.1 D). After suture removal, respective values were significantly lower in the EXCIMER group (2.8 +/- 2.0 D/3.0 +/- 2.1 D/3.8 +/- 2.6 D) than in the CONTROL group (4.2 +/- 2.4 D/6.1 +/- 2.7 D/6.7 +/- 3.1 D) (P < 0.0009). In the EXCIMER versus CONTROL group, mean VA increased from 20/100 versus 20/111 (P > 0.05) before surgery, to 20/31 versus 20/38 before (P = 0.001) and to 20/28 versus 20/39 (P < 0.00001) after suture removal. Mean spherical equivalent was significantly less myopic in the EXCIMER group before (-0.9 +/- 3.6 D vs. -2.6 +/- 3.4 D) (P = 0.01) and after suture removal (-1.4 +/- 3.1 D vs. -2.4 +/- 3.5 D) (P = 0.02). Mean SRI (P = 0.04) and PVA (P = 0.007) were significantly more favorable in the EXCIMER versus CONTROL group after suture removal (0.91 +/- 0.45 and 0.82 +/- 0.15 vs. 1.05 +/- 0.46 and 0.73 +/- 0.18).

CONCLUSIONS

Postkeratoplasty results seem to be superior using nonmechanical excimer laser trephination. Thus, this methodology is recommended as the procedure of first choice in avascular corneal pathologies requiring PK.

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.

Analysis of videokeratography after penetrating keratoplasty: topographic characteristics and effects of removing running sutures

OBJECTIVE

Previous studies have shown that removal of running sutures after penetrating keratoplasty causes unpredictable changes in astigmatism. The current study was conducted to investigate whether computer-assisted videokeratography is beneficial for predicting visual outcomes after running sutures are removed.

DESIGN

The design was that of a prospective clinical study.

PARTICIPANTS

The authors prospectively studied 29 consecutive eyes undergoing a 10-0 nylon running suture removal after penetrating keratoplasty.

INTERVENTIONS

Videokeratography was performed before, 1 week, 1 month, and 3 months after removal of sutures.

MAIN OUTCOME MEASURES

Changes in refractive and topographic astigmatism after suture removal were measured. Topographic patterns and their quantitative descriptors also were analyzed.

RESULTS

An asymmetric bowtie was the most common videokeratography pattern both before and after suture removal. After suture removal, the incidence of peripheral corneal steepening increased significantly (2 vs. 21 eyes, P < 0.0001), and that of focal flattening of the midperipheral cornea decreased (13 vs. 5 eyes, P = 0.046). The mean topographic astigmatism, surface regularity index, and corrected visual acuity were improved significantly by suture removal in eyes that had localized flattening but not in eyes without this finding. Eyes having either skewed axis in astigmatism or topographic astigmatism of more than 9 diopters also showed significant decreases in astigmatism.

CONCLUSIONS

Suture removal after keratoplasty is advantageous for both reducing astigmatism and normalizing topography, especially in eyes that have localized flattening of the midperipheral cornea. Predictability of visual outcomes of a running suture removal in postkeratoplasty eyes may be improved by the use of videokeratography.

Characteristics of normal corneal topography using the EyeSys corneal analysis system

PURPOSE

To study the parameters of corneal topography of normal eyes using the Corneal Analysis System (CAS, EyeSys Technologies) to determine the types and frequency of patterns and parameters.

SETTING

University of Illinois Eye Center, Chicago, Illinois, USA.

METHODS

Three independent, masked judges, using a forced-choice paradigm, classified corneal topography patterns into six categories on one randomly selected, normal eye of 100 persons who did not wear contact lenses. The patterns were defined by using the midpoint dioptric bin and a 0.50 diopter (D) steeper bin.

RESULTS

The pattern frequency using the mid-dioptric bin was teardrop (6%), amorphous (11%), round (11%), symmetric bow tie (17%), asymmetric bow tie (1 %), kidney (22%), and oval (32%). Mean refractive and keratometric cylinders, respectively, were teardrop (0.13 and 0.15 D), amorphous (0.15 and 0.49 D), round (0.18 and 0.56 D), oval (0.21 and 0.56 D), kidney (0.51 and 0.72 D), and bow tie (1.18 and 1.82 D). Pattern frequency using the 0.50 D steeper bin was round (2%), oval (5%), teardrop (6%), kidney (15%), amorphous (17%), asymmetric bow tie (17%), and symmetric bow tie (37%). Mean refractive and keratometric cylinders, respectively, were round (0.13 and 0.32 D), amorphous (0.25 and 0.38 D), kidney (0.11 and 0.42 D), oval (0.40 and 0.59 D), teardrop (0.08 and 0.75 D), and bow tie (0.65 and 1.09 D). Mean flat and steep contours were 41.76 D (95% confidence interval [CI], 38.68 to 44.84 D) and 44.15 D (95% CI, 41.00 to 47.31 D), respectively. Mean contour range was 2.40 D (95% CI, 0.61 to 4.17 D).

CONCLUSION

The data suggest that for 95% of normal corneas, corneal contours will be steeper than 38.50 D, flatter than 47.50 D, and have a contour range less than 4.25 D when using the EyeSys CAS.

The effect of artificial tears on computer-assisted corneal topography in normal eyes and after penetrating keratoplasty

PURPOSE

To examine the effect of adding artificial tears for one minute to normal eyes and eyes that have undergone keratoplasty by using computer-assisted videokeratography.

METHODS

We prospectively analyzed 24 normal corneas (24 patients) chosen by random number table (reproducibility section [10 eyes], tear section [14 eyes]) as well as 14 postkeratoplasty corneas. The parametric descriptors analyzed statistically included the simulated keratometry value, surface asymmetry index, surface regularity index, power at the vertex normal, and the pupil offsets from the visual axis. Vectoral analysis was used to calculate the difference in power and axis between the simulated keratometry values before and after tear instillation.

RESULTS

In normal eyes, tear instillation increased the surface asymmetry index (0.28 +/- 0.34, P = .01), changed the simulated keratometry value (0.23 diopter by 27.8 degrees), and power (0.79 +/- 0.82 diopters, P = .004) and location (0.91 +/- 0.76 mm) of the steepest point of the cornea changed. In postkeratoplasty eyes, the surface regularity index decreased (0.49 +/- 0.80, P = .04), surface asymmetry index decreased (0.37 +/- 1.03, P = .21), mean simulated keratometry value changed (1.04 diopters by 1.01 degrees), and power (0.70 +/- 2.34 diopters, P = .28) and location (1.04 +/- 1.17 mm) of the steepest point of the cornea changed. Changes were greater than the variability of the surface regularity index (0.07 +/- 0.05), surface asymmetry index (0.04 +/- 0.03), simulated keratometry value power (0.08 +/- 0.06 diopter), and axis (4.6 +/- 5 degrees).

CONCLUSIONS

The addition of artificial tears to normal or regular and symmetric eyes that have undergone keratoplasty worsened symmetry and changed the power and location of the steepest point. However, the addition of artificial tears to irregular eyes that have undergone penetrating keratoplasty created a more regular and symmetric surface and significantly altered the simulated keratometry values. We recommend that corneal topography be performed before the application of artificial tears.

An adjustable double running suture technique for keratoplasty

In a retrospective analysis, we examined 30 consecutive cases of penetrating keratoplasty in which a double running 10-0/11-0 nylon suture technique was used and the 10-0 suture was adjusted early in the postoperative period to reduce astigmatism. When the response to suture adjustment was inadequate, the presence of the 11-0 suture allowed for early (ten to 18 weeks) removal of the 10-0 suture. Rapid visual recovery (12.3 +/- 0.95 weeks; mean +/- standard error) and low levels of final astigmatism (2.66 +/- 0.24 diopters) were achieved. Visual acuity was 20/20 to 20/40 in 25 of the 28 patients (89%) who were visually rehabilitated. In these 28 patients, visual acuity remained stable for the remainder of the study. All patients had a minimum of six months' follow-up from the time of surgery; mean follow-up was 10.6 +/- 1.70 months.

Computerized topographic analysis of the healing graft after penetrating keratoplasty for keratoconus

After penetrating keratoplasty, visual rehabilitation can be slow and is largely a function of corneal surface configuration. Computerized topographic analysis allows the detailed study of corneal surface factors that determine the optical function of the graft. We performed a prospective, longitudinal study of eight patients with keratoconus by using computerized topographic analysis to determine the rate and pattern of postoperative surface normalization and stabilization. Study data included Snellen visual acuity, contrast sensitivity function, central keratometry, photokeratoscopy, and computerized topographic analysis. Data were collected preoperatively and at one week, one month, two months, three months, and six months postoperatively. Results demonstrate that the greatest configurational changes both topographically and functionally occur in the first month after keratoplasty. The computer-generated surface asymmetry index and the surface regularity index correlated well with improvement in Snellen visual acuity measurements. Contrast sensitivity function was depressed initially but improved to well above preoperative values by one month postoperatively and paralleled the improvement in the surface indices and visual acuity. The axis of astigmatism stabilized by one month postoperatively. Our data indicate that topographic analysis provides a good indication of the rate and course of optical stabilization during the early healing process after keratoplasty and correlates well with visual function in the otherwise normal eye.

11-0 mersilene as running suture for penetrating keratoplasty

We evaluated astigmatic results and complications of the combined suturing technique in penetrating keratoplasty by using 11-0 Mersilene as a running suture. Twenty-seven grafts were studied for a follow-up that ranged between ten and 46 months (mean, 27.2 months). During the study, complications included three graft failures, one instance of inadvertent breakage of the running suture, one instance of one suture bite cutting through the recipient cornea, and suture microabscesses in two eyes. Keratometric astigmatism was 2.5 +/- 2.1 diopters at six months, was 2.4 +/- 2.3 diopters at 12 months, and was 2.5 +/- 2.0 diopters at 24 months. Our data indicate that 11-0 Mersilene is suitable for the running suture in corneal transplants in the combined technique. Spontaneous suture dissolution did not occur throughout the follow-up period. The use of a less biodegradable suture enables the maintenance of low levels of astigmatism for longer periods when compared with a previous study that used 11-0 nylon suture.

Running nylon suture dissolution after penetrating keratoplasty

We attempted to evaluate whether the low degrees of astigmatism achieved early in the postkeratoplasty period with the combined interrupted/running suturing technique were maintained for long periods of time. For 13 to 70 months (mean, 30.2 months), we monitored a group of patients (25 eyes) who had previously undergone the combined interrupted/running suturing technique (12 interrupted 10-0 nylon sutures and one running 11-0 nylon suture). Nine running sutures broke spontaneously, causing a significant increase of the keratometric astigmatism of the entire population from 1.7 +/- 1.6 to 3.4 +/- 2.6 diopters (mean +/- standard deviation). The mean vector-corrected change in astigmatism after suture breakage was 4.9 +/- 2.6 diopters. Surgical procedures to reduce astigmatism were required in many of the eyes in which the 11-0 running nylon suture broke. Our results suggested that 11-0 nylon is not an ideal material for the running suture because its high rate of spontaneous disruption leads to undesired, statistically significant increases in postkeratoplasty astigmatism. Further, our results indicated that the selective suture technique can maintain low degrees of astigmatism only if the sutures remain intact. Studies of the effect of keratoplasty suturing techniques on astigmatism should probably include a follow-up that is sufficiently long to indicate its long-term value to the patient.

Corneal topography for selective suture removal after penetrating keratoplasty

Twenty-nine suture removals from 20 eyes (21 patients) on which penetrating keratoplasty had been performed were analyzed in a nonrandomized consecutive study to evaluate the role of computer-assisted corneal topography in selective suture removal to reduce astigmatism. Topographic guidance for suture removal resulted in a net decrease in refractive and keratometric astigmatism in 21 of the 29 cases. The net reduction in astigmatism averaged 1.4, 0.9, and 1.0 diopters when measured by refraction, keratometry, and topography, respectively. The preliminary choice of sutures to be removed on the basis of refraction, keratometry, and inspection was changed in 20 of the 29 cases when information added by the topographic map was considered. Although many variables of suture removal remain unpredictable, computer-assisted corneal topography is a powerful means of describing corneal power after penetrating keratoplasty and is useful as a guide in selective suture removal for reduction of astigmatism.

Advances in the analysis of corneal topography

Recent advances in topographic analysis have provided powerful tools for detecting subtle, but clinically significant, alterations of corneal contour. This article compares keratometry, keratoscopy, and computer-assisted topographic analysis and provides specific examples of the sensitivity of computer-assisted systems in revealing topographic alterations that were not previously discernable. Quantitative descriptors of corneal topography such as the surface asymmetry index, the surface regularity index, and simulated keratometry value augment the information provided by color-coded topographic maps.

An adjustable single running suture technique to reduce postkeratoplasty astigmatism. A preliminary report

The authors compared postkeratoplasty astigmatism over a 4-month period after surgery in a randomized, prospective study of two groups of patients (total N = 18) who received two different suture techniques. The test group N = 8) had a single running suture with postoperative suture adjustment; on the basis of computer-assisted topographic analysis, the suture was tightened in the flatter meridian and loosened in the steeper meridian in the first month after surgery. The control group (N = 10) had a standard double running suture procedure with no postoperative adjustment; the single running 10-0 nylon suture was removed 3 months after surgery. Four months after penetrating keratoplasty, mean (+/- standard deviation) astigmatism in the test group was 1.7 +/- 0.7 diopters (D), and all patients had less than 2.6 D of astigmatism. In the control group, mean astigmatism was significantly higher (5.4 +/- 2.4 D; range, 0.7-9.0 D; P less than 0.01). The results suggest that postkeratoplasty astigmatism can be reduced with the single running suture technique accompanied by postoperative suture adjustment.