Penetrating keratoplasty for keratoconus: visual outcome and success

Biomechanical Model of Corneal Transplantation

PURPOSE

Refractive consequences of corneal transplants are analyzed using corneal biomechanical models assuming homogeneous and inhomogeneous stiffness distributions across the cornea. Additionally, refractive effects of grafts combined with volume removal procedures are also evaluated to develop methods to reduce postoperative refractive management of patients.

METHODS

Refinements of a two-dimensional finite element model are applied to simulate the biomechanical and refractive effects of different corneal transplant procedures: anterior lamellar keratoplasty, posterior lamellar keratoplasty, and penetrating keratoplasty. The models are based on a nonlinearly elastic, isotropic formulation. Predictions are compared with published clinical data.

RESULTS

The model simulating the penetrating keratoplasty procedure predicts more change in the postoperative corneal curvature than models simulating anterior lamellar keratoplasty or posterior lamellar keratoplasty procedures. When a lenticle-shaped tissue with a central thickness of 50 microns and a diameter of 4 mm is removed from the anterior corneal surface along with the anterior lamellar keratoplasty or posterior lamellar keratoplasty, the models predict a refractive correction of -8.6 and -8.9 diopters, respectively.

CONCLUSIONS

Simulations indicate that a posterior lamellar keratoplasty procedure is preferable for obtaining a better corneal curvature profile, eliminating the need for specific secondary treatments.

Outcomes of penetrating keratoplasty in keratoconus

PURPOSE

Keratoconus (KCN) is one of the most common indications of corneal transplantation in Iran. This study was conducted to determine the outcomes of penetrating keratoplasty (PK) for KCN in patients operated in a private practice setting from 1994 to 2001.

METHODS

This longitudinal retrospective study included 164 eyes of 164 patients. Variables included preoperative keratometry, trephination and suturing techniques, donor-recipient disparity, surgical complications, immunologic rejection, graft clarity, postoperative spherical and cylindrical refractive error, keratometry, uncorrected and best spectacle-corrected visual acuity, suture management, and the results of keratorefractive procedures.

RESULTS

Patients were followed for a mean period of 33.5 months. Mean postoperative best spectacle-corrected visual acuity (BSCVA) at last follow-up was 0.14 +/- 0.11 LogMAR (20/25); mean spherical error and mean corneal astigmatism were -0.61 +/- 2.6 and 3.4 +/- 1.8 D, respectively. Final visual outcomes were not significantly correlated with trephination and suturing techniques or severity of the ectasia. Although donor-recipient disparity did not affect final astigmatism, more myopic shift was observed with greater disparity, but this finding was not of statistical significance. Overall, 26.8% of the patients required keratorefractive surgery, which resulted in 2.9 D reduction in corneal astigmatism. Immunologic graft rejection occurred in 28% of cases; however, all episodes responded to medical management, and none resulted in graft failure.

CONCLUSION

Penetrating keratoplasty is a safe and effective procedure with remarkable optical and visual outcomes for patients with keratoconus who are contact lens intolerant or have unacceptable corrected visual acuity. Neither severity of the disorder nor trephination and suturing techniques significantly affects final visual outcomes. Less graft-recipient disparity (0.25 versus 0.50 mm) seems to induce less myopic shift.

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.

Results of deep lamellar keratoplasty using the big-bubble technique in patients with keratoconus

PURPOSE

To evaluate the efficacy of deep lamellar keratoplasty using the big-bubble technique in patients with keratoconus.

DESIGN

Interventional case series.

METHODS

Thirteen eyes of 12 patients (eight male and four female subjects) with moderate to advanced keratoconus and intolerance to contact lens wear were included in this study. Deep lamellar keratoplasty was performed by the intrastromal air injection technique. Full-thickness donor tissue devoid of Descemet membrane and endothelium was then sutured into place. Best-corrected visual acuity, refractive results, surgical technique, and complication rates were analyzed.

RESULTS

Big bubble was successfully achieved in nine eyes (69.2%). Average postoperative best-corrected visual acuity was 20/25 (range 20/50 to 20/20) at a mean follow-up of 5 months. Intraoperative microperforation of Descemet membrane occurred in two eyes (15.3%). Three eyes (23%) developed a steroid-induced increase in intraocular pressure, which responded to medical therapy.

CONCLUSIONS

Deep lamellar keratoplasty that uses the big-bubble technique is safe and effective in patients with keratoconus. Visual outcome is comparable to standard penetrating keratoplasty, without the risk of endothelial rejection.

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.

Treating Keratoconus With Intacs Corneal Ring Segments

PURPOSE

To assess the safety and efficacy of Intacs inserts for the treatment of mild to moderate keratoconus.

METHODS

In a nonrandomized prospective clinical trial, 50 eyes of 37 patients with mild to moderate keratoconus were implanted with asymmetrical pairs of Intacs segments. Patients were interviewed and observed preoperatively and 24 hours, 1 week, 1, 3, 6, and 12 months postoperatively. Main outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, satisfaction with vision and trouble with vision, Visual Function-7 score, and surgically induced change in corneal astigmatism.

RESULTS

Of the 50 operations performed, 92% were successful. Mean follow-up was 6.3 +/- 3.2 months. In 4 (8%) eyes, both Intacs segments were removed. In addition, 7 refractive adjustments in 7 eyes were performed successfully to improve visual and surgical outcome. Both BSCVA and UCVA improved throughout follow-up. Visual functioning index improved from 61.6 +/- 21.1 to 80.8 +/- 22.5, and the percentage of satisfaction with vision improved from 24.3% to 87.5% at 12 months. Vector analysis of astigmatism correction showed that the mean change in corneal astigmatism was 2.9 +/- 2.9 D at 6 months postoperatively. By selecting patients in whom astigmatism correction was best (index of success >0.5), an analysis was performed to determine individual factors important in successful surgery. Preoperatively these 11 (22%) eyes did not differ significantly from the remaining eyes and the only significant value was low K readings in the flat axis.

CONCLUSIONS

Asymmetric Intacs placement improves BSCVA and UCVA and reduces astigmatism in patients with mild to moderate keratoconus. The procedure of Intacs placement is safe and effective. The change in astigmatism correction is unpredictable.

Implantation of Artisan Toric Phakic Intraocular Lenses for the Correction of Astigmatism and Spherical Errors in Patients With Keratoconus

PURPOSE

To evaluate the correction of astigmatism and spherical ametropia in patients with keratoconus through implantation of an Artisan toric phakic intraocular lens (PIOL) (Ophtec, Groningen, The Netherlands).

METHODS

Artisan toric PIOLs were implanted uneventfully in both eyes of three patients with keratoconus with clear central corneas and contact lens intolerance.

RESULTS

Best spectacle-corrected subjective visual acuity after lens implantation was unchanged in one eye and improved in five eyes. Spherical equivalent refraction was significantly reduced in all eyes (P=.03). The safety index was 1.49.

CONCLUSIONS

The implantation of an Artisan toric PIOL may be an alternative for treating astigmatism and myopia in contact lens intolerant patients with keratoconus with clear central corneas. Especially in patients with associated myopia, this procedure is worth considering before planning a penetrating keratoplasty.

Le kératocône : options chirurgicales actuelles

The treatment of keratoconus is in part dependant on the severity of the disease process. When contact lenses fail because of patient intolerance or insufficient acuity to meet the patient's needs, penetrating keratoplasty is the usual surgical modality considered for satisfactory visual rehabilitation. Keratoconus is considered to be a contraindication for incisional refractive surgery such as radial keratotomies or LASIK because of the corneal instability conferred by these procedures. When the cornea is transparent, INTACS implantation is a refractive modality that may improve visual function and in some instances prevent the need for corneal transplantation in select patients with keratoconus.

A correlated frailty model for analysing risk factors in bilateral corneal graft rejection for Keratoconus: a Bayesian approach

There are many unknown causes that increase the rate of corneal graft rejection. In bilateral cases, some of these unknown causes are common, and some are individual factors. In this paper, we use a correlated frailty model to analyse risk factors for bilateral corneal graft in Keratoconus. Applying the piecewise constant baseline hazard model, we have performed a Bayesian analysis of the correlated frailty model using the Markov chain Monte Carlo method. The correlated frailty model and the shared frailty model are compared by deviance information criterion. The results show more accurate and better fit for the correlated frailty model.

Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus

OBJECTIVE

To compare the therapeutic outcomes after deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) in patients with keratoconus.

DESIGN

Retrospective case-control study.

PARTICIPANTS

We reviewed the clinical notes of 47 patients diagnosed clinically with keratoconus who had received DLK (26 eyes of 25 patients) or PK (25 eyes of 22 patients) at Moorfields Eye Hospital or the Royal Shrewsbury Hospital between 1994 and 2001. The patients in the 2 groups were matched for severity of their keratoconus by preoperative visual acuity.

METHODS

Deep lamellar keratoplasty was performed with the Melles technique in 7 eyes and the technique described by Sugita and Kondo in 19 eyes. Penetrating keratoplasty was performed with a standard technique using a Hessburg-Barron trephine. A single continuous 16-bite 10-0 nylon suture was placed and adjusted in both groups.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), refractive results, surgical techniques for DLK, and complication rates were analyzed.

RESULTS

The 25 patients with keratoconus who underwent DLK had a mean age of 32.6 years and a median follow-up of 28 months. The mean age of the 22 patients who underwent PK for keratoconus was 34 years. This group was followed up for a median time of 55 months. The median final BCVA of patients in the DLK group was 6/9 and in the PK group 6/6 (no statistical significance). The median result for the final spherical equivalent power in both groups was mild myopia, although the DLK group had more myopia, and the median astigmatism was less than 5.00 diopters cylinder for both groups. Complication rates were similar for DLK and PK, although the nature of the complications varied.

CONCLUSIONS

Penetrating keratoplasty is no longer an automatic choice for the surgical treatment for keratoconus; DLK seems to be a safe alternative. Best-corrected visual acuity, refractive results, and complication rates are similar after DLK and PK. Deep lamellar keratoplasty is more technically challenging but allows the risk of endothelial rejection to be avoided and may reduce the risk of late endothelial failure.

Late-Stage Progressive Corneal Astigmatism After Penetrating Keratoplasty for Keratoconus

PURPOSE

Progressive corneal astigmatism occurring at least 10 years after penetrating keratoplasty for keratoconus is a late-phase complication of surgery. This report characterizes this condition in a series of patients from three corneal referral centers in the United States.

METHODS

Charts were retrospectively reviewed which met the following criteria: penetrating keratoplasty performed for keratoconus at least 10 years ago, keratometry or simulated keratometry from topography as well as manifest refraction recorded at least 6 months after the last suture removal ("baseline"), and an increase in corneal astigmatism of at least three D over baseline recorded at least 5 years later. Patients who had any other corneal or intraocular surgery performed were excluded.

RESULTS

Data from 15 patients (11 males and 4 females) who had penetrating keratoplasties performed by 8 different surgeons are included in this descriptive series. Postoperative follow-up averaged 17.27 years (range 11-24 years). The average donor button size was 7.83 mm (range 7.25-8.5 mm). Baseline corneal astigmatism was obtained an average of 5.2 years after penetrating keratoplasty (range 1.5-16 years) and was on average 3.57 +/- 1.8 D (10 with-the-rule [WTR], 3 against-the-rule [ATR], 2 oblique). Corneal astigmatism significantly increased to an average of 11.23 +/- 3.56 D (range 8.00-19.37 D, P < 0.0001) and most astigmatism was regular and WTR (9 WTR, 3 ATR, 3 oblique) 15.3 years (range 10-22 years) after surgery. Inferior steepening on topography was often noted, even those with oblique and ATR axes.

CONCLUSIONS

High, late-stage, regular astigmatism after penetrating keratoplasty for keratoconus is described in a series of patients occurring at least 10 years after surgery. Possible mechanisms of this progressive astigmatism are recurrence of keratoconus in the graft, progressive corneal thinning of the host cornea, or progressive misalignment of the graft-host interface over time.

Effect of hinged lamellar keratotomy on post-keratoplasty astigmatism and vision

PURPOSE

To show that hinged lamellar keratotomy alone affects refraction and vision in post-keratoplasty eyes.

METHODS

A retrospective, non-comparative, interventional case series was conducted on 28 eyes of 26 patients who had two-stage laser in situ keratomileusis (LASIK) after penetrating keratoplasty. Records were reviewed with respect to the hinged lamellar keratotomy component of the procedure. The interval between keratoplasty and keratotomy was at least 1 year, and the follow-up period averaged 29 +/- 10 days. The Automated Corneal Shaper with nasal hinge was used. In addition to basic empirical astigmatism calculations, the Alpins method of astigmatism analysis was also employed to ensure that the influence of changes in cylinder axis were correctly taken into account when calculating the refractive change.

RESULTS

Surgically induced astigmatism from hinged lamellar keratotomy was not statistically significant in this series; however, the range in values (-9.06 to +7.57 D) has potential clinical ramifications. Nearly 70% of cases studied experienced surgically induced astigmatism of at least 2 D. Mean preoperative uncorrected vision was logMAR 1.06 +/- 0.41, which improved marginally postoperatively to logMAR 1.03 +/- 0.44 (P = 0.36). Best spectacle-corrected visual acuity averaged logMAR 0.21 +/- 0.16 preoperatively, improving to logMAR 0.09 +/- 0.15 (range -0.18 to 0.42) postoperatively, which was a statistically significant improvement (P < 0.01). No difference in refractive or visual outcomes was identified when those with keratoconus were compared to those with other underlying corneal disease processes.

CONCLUSION

Although mean surgically induced astigmatism was not statistically significant, hinged lamellar keratotomy caused considerable changes in astigmatism in nearly 70% of post-keratoplasty eyes studied. This suggests that clinically significant inaccuracies may result if a one-stage LASIK procedure is performed on such patients. The authors suggest that reassessment of refraction after keratotomy may improve refractive outcomes.

Late onset post-keratoplasty astigmatism in patients with keratoconus

AIM

10 eyes of 10 patients are reported where progression of keratoconus in the host cornea occurred more than 10 years after penetrating keratoplasty with resultant increase in astigmatism. The technique and results of graft refractive surgery in seven eyes are presented.

METHODS

The clinical features and management of these patients were retrospectively analysed. Graft refractive surgery involved an incision at the graft-host junction adjacent to the host thinning with compressive resuturing. Astigmatic changes were calculated using vector analysis.

RESULTS

There were seven men and three women with a mean age of 41.2 years. The average age when undergoing penetrating keratoplasty in the affected eye was 28.4 years and the average time after penetrating keratoplasty until keratoconus appeared in the host cornea defined by host thinning was 13.5 years. The mean cylinder power before host thinning was noted was 5.07 D (SD 2.19) and the mean after host thinning was 11.0 D (2.53). The mean vector calculated disease induced astigmatism magnitude was 7.59 D (3.09). Graft refractive surgery was performed in seven eyes. The mean cylinder power before and after graft refractive surgery was 11.28 D (2.15) and 7.09 D (5.53) respectively. The surgically induced astigmatism vector magnitude was 7.36 D (4.88).

CONCLUSION

Progression of keratoconus in the host cornea late after penetrating keratoplasty is characterised by a large astigmatic change where the flat axis of astigmatism passes through an area of host thinning visible on slit lamp examination. Compressive resuturing performed in the area of host thinning resulted in satisfactory reduction of astigmatism.

Rapid Visual Rehabilitation After Endothelial Transplants With Deep Lamellar Endothelial Keratoplasty (DLEK)

OBJECTIVE

To evaluate the speed of visual recovery in 30 consecutive patients with Fuchs endothelial dystrophy who received deep lamellar endothelial keratoplasty (DLEK) transplant surgery.

METHODS

Best spectacle-corrected visual acuity (BSCVA) by manifest refraction and uncorrected visual acuity (UVA) were prospectively measured at preop, at 1 week, and at 1, 3, 6, 12, and 18 months after DLEK. The LogMAR of the postop vision was compared against each patient's preop vision. Visual results at 6 months were also compared against potential acuity meter (PAM) results in 27 patients. All eyes had reached at least the 6-month follow-up interval.

RESULTS

Two of the first 32 eyes originally enrolled in the protocol were converted at surgery to standard penetrating keratoplasty (PK), and so DLEK data were obtained on 30 eyes for this report. Average BSCVA and UVA were better than preop vision at every time point, achieving statistical significance by 3 months (P < 0.05). Average preop BSCVA was 20/162 (range 20/40 to CF), improving to 20/63 at 3 months (range 20/25 to 20/200), 20/56 at 6 months, 20/51 at 1 year, and 20/46 at 18 months. Of the 27 patients who had PAM testing, 52% (14 of 27) had BSCVAs within 1 line of their PAM at 3 months, 63% (17 of 27) were within 1 line at 6 months, 71% (12 of 17) were within 1 line at 1 year, and 83% (10 of 12) were within 1 line at 18 months (P < 0.05 compared with preop from 3 months on).

CONCLUSION

DLEK surgery preserves the normal corneal surface topography and allows rapid visual recovery of useful vision by 3 months. The visual acuity continues to improve over time.

Indications for and outcomes of penetrating keratoplasty performed by resident surgeons

PURPOSE

To analyze the indications for and outcomes of penetrating keratoplasty (PKP) performed by resident surgeons at both county hospital and Veterans Affairs facilities.

DESIGN

Observational case series.

METHODS

Retrospective review of 79 eyes from 61 patients undergoing PKP from January 1, 1997, through December 31, 2001, to determine indications for surgery and outcomes, including graft clarity and final visual acuity.

RESULTS

There were 52 (65.8%) primary and 27 (34.2%) repeat transplants performed. Follow-up after surgery averaged 21.9 months. Indications for PKP included failed graft, 23 (29.1%), bullous keratopathy, 17 (21.5%), keratoconus, 16 (20.3%), corneal scar, 15 (19.0%), corneal perforation from infection, 5 (6.3%), and Fuchs endothelial dystrophy, 3 (3.8%). Twenty-one eyes had pre-existing ocular disease limiting final acuity. Overall, 51 grafts (64.6%) remained clear. More primary than repeat grafts remained clear (75% vs 44.4%, P =.012) and achieved 20/40 or better final acuity (30.8% vs 11.8%, P =.05). Excluding failed grafts or eyes with limited visual potential, final acuities achieved were: 19 (47.5%) 20/40 or better, 18 (45%) 20/50 to 20/150, 3 (7.5%) 20/200 or worse. Grafts remaining clear by indication were: failed graft, 9 (39.1%); keratoconus, 14 (87.5%); bullous keratopathy, 13 (76.5%); corneal scar, 10 (66.7%); corneal perforation, 2 (40%); Fuchs, 3 (100%). Eyes achieving final acuity of 20/40 or better by indication were: keratoconus, 9 (56.2%); failed graft, 3 (13%); bullous keratopathy, 3 (17.7%); corneal scar, 2 (13.3%); corneal perforation, 0 (0%); Fuchs, 2 (66.7%).

CONCLUSIONS

County hospital and Veterans Affairs facilities provide a challenging subset of patients for penetrating keratoplasty. Failed graft was the leading indication for transplantation for our population. Graft clarity and final visual acuity varied by indication for transplantation. Resident surgeons can achieve favorable results for penetrating keratoplasty performed at these venues, especially for primary transplants.

Long-term graft survival after penetrating keratoplasty

PURPOSE

To determine long-term graft survival rates and causes of secondary graft failures for a large series of penetrating keratoplasties (PKPs).

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Longitudinal review of 3992 consecutive eyes that underwent PKP at a large tertiary care referral center from 1982 through 1996. Data were collected retrospectively from August 1982 through December 1988 and prospectively thereafter.

INTERVENTION

Three thousand six hundred forty primary grafts and 352 regrafts.

MAIN OUTCOME MEASURES

Corneal graft survival and etiology of graft failures. Patients were evaluated preoperatively and at 1, 3, 6, 9, 12, 18, and 24 months after transplant, then at yearly intervals.

RESULTS

Mean recipient age was 67 years (range, 1-98 years). The predominant indications for PKP were pseudophakic bullous keratopathy (32%) and Fuchs' dystrophy (23%). Graft failure occurred in 10% (385) of the eyes. The most common causes of secondary graft failure were endothelial failure (29%) or immunologic endothelial rejection (27%). Survival of first time grafts was 90% at 5 years and 82% at 10 years. Initial regrafts had significantly lower 5-year and 10-year survival rates, 53% and 41%, respectively. The highest 5-year and 10-year survival rates were noted in primary grafts for eyes with a preoperative diagnosis of keratoconus (97% and 92%, respectively), or Fuchs' dystrophy (97% and 90%, respectively). Primary grafts for aphakic bullous keratopathy without intraocular lens placement had the lowest 5-year survival rate, 70%.

CONCLUSIONS

The 5-year and 10-year survival rates in this series demonstrate that PKP is a safe and effective treatment for the corneal diseases commonly transplanted in the United States. However, endothelial failure and immunologic graft rejection were persistent risks over the long term, supporting the need for continued patient follow-up. Regrafts, aphakic eyes without intraocular lens placement at the time of transplant, and corneas with deep stromal vascularization had reduced graft survival rates. Pseudophakic bullous keratopathy grafts with a retained posterior chamber intraocular lens were at increased risk of endothelial failure compared with primary grafts done for other causes or compared with pseudophakic bullous keratopathy grafts done with intraocular lens exchange.

Long-term progression of astigmatism after penetrating keratoplasty for keratoconus: evidence of late recurrence

PURPOSE

To study changes in astigmatism throughout a 20-year period using keratometry and refraction in patients who underwent penetrating keratoplasty (PKP) for keratoconus.

METHODS

We reviewed the charts of patients who underwent PKP for keratoconus from 1975 to 1979 and recorded preoperative refraction, stage of keratoconus, laterality of surgery, graft size, suture technique, time of suture removal, keratometry, subjective refraction at 1, 3, 5, 7, 10, 15, 20, and 25 years after suture removal, and slit-lamp findings.

RESULTS

Eighty eyes with a mean follow-up of 20 years (range, 15-25) were included in the study. Graft size, suture technique, and time of suture removal had no significant influence on the astigmatism at the last examination. We observed a stabilization of keratometric astigmatism in the first 7 years (4.05 +/- 2.29 D 1 year after suture removal, 3.90 +/- 2.28 D at year 3, 4.03 +/- 2.49 D at year 5, 4.39 +/- 2.48 D at year 7) followed by a progressive increase from 10 years after suture removal until the last follow-up visit (5.48 +/- 3.11 D at year 10, 6.43 +/- 4.11 D at year 15; 7.28 +/- 4.21 D at year 20, and 7.25 +/- 4.27 D at year 25). The mean absolute value of the difference vector (DV) calculated by vector analysis was 7.17 +/- 4.35 D (0-18.33). In 70% of cases, progression of the astigmatism was evident with mean absolute DV of 9.10 +/- 3.65 D. There was a significant correlation between the preoperative and final axis of astigmatism (Pearson r = 0.39, p = 0.0008). There was also a slight positive correlation coefficient between the DV of the eyes in bilateral cases, but it was not significant (Spearman's r = 0.2226, p = 0.34). The major late slit-lamp finding was a peripheral crescent-shaped thinning at the graft-host junction with absence of Bowman's layer on histopathology.

CONCLUSION

In spite of refractive stability obtained during the first years after PKP for keratoconus, increasing astigmatism thereafter suggests that there is a progression of the disease in the host cornea.

Prediction of visual outcome after penetrating keratoplasty for pseudophakic corneal edema

OBJECTIVE

To evaluate the ability to predict visual outcome after penetrating keratoplasty (PKP) in patients with pseudophakic corneal edema (PCE) or aphakic corneal edema (ACE) based on preoperative parameters available from the patient history and ocular examination.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Forty-eight patients who underwent 59 PKP procedures for PCE between 1997 and 2000 by two cornea specialists.

METHODS

Medical records were retrospectively analyzed for variables in the history and ocular examination before PKP and visual outcome after PKP. Variables included age, gender, presence of diabetes or cardiovascular disease, method of intraocular lens (IOL) implantation during cataract surgery, vitreous loss during cataract surgery, time between cataract and PKP surgery, and maximal visual acuity reached after cataract surgery. The predictive value of each preoperative variable on post-PKP visual outcome was assessed using both univariate and multiple regression analyses.

MAIN OUTCOME MEASURES

Statistical significance for the predictive value of each preoperative variable on post-PKP visual outcome.

RESULTS

Best-corrected visual acuity (BCVA) of 20/40 or better was achieved in 13 patients (27%). The strongest predictor of this outcome was implantation of a bag-fixated or sulcus-fixated IOL at the time of cataract surgery (P = 0.007; odds ratio, 15.8; 95% confidence interval, 1.2-208). Less significant variables included BCVA after cataract surgery, time between cataract surgery and PKP, and gender.

CONCLUSIONS

In planning and advising patients with pseudophakic or aphakic corneal edema who are candidates for PKP, the method of IOL implantation during the cataract surgery is the single most significant predictor of visual acuity after corneal transplantation. Bag-fixated or sulcus-fixated posterior chamber IOL was associated with a better visual outcome than anterior chamber IOL, scleral-fixated posterior chamber IOL, or aphakia.

Management of keratoconus with Intacs

PURPOSE

To prospectively study the effects of the use of Intacs microthin prescription inserts for the management of keratoconus.

DESIGN

Prospective nonrandomized clinical trial.

METHODS

Thirty-three eyes of 26 keratoconus patients (17 males and 9 females) ages 21 to 51 years (mean age, 32 +/- 9.7 years) were included in the current study. All patients had clear central corneas and contact lens intolerance. Patients were excluded if any of the following criteria applied after the preoperative examination: previous intraocular or corneal surgery; history of herpes keratitis; diagnosed autoimmune disease; and systemic connective tissue disease. Two Intacs segments of 0.45-mm thickness were inserted in the cornea of each eye, aiming at embracing the keratoconus area to try to achieve maximal flattening. Preoperative examination included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, keratometric data, and corneal topography.

RESULTS

Intacs were successfully implanted in all eyes. In one eye Intacs were removed after 3 months because of their improper (superficial) placement. The follow-up ranged from 1 to 24 months (mean: 11.3 months). The mean UCVA significantly improved from 0.13 +/- 0.14 (range, counting fingers [CF]-0.5) to 0.39 +/- 0.27 (range, CF-1.0) (P <.01). Of 33 eyes, 2 eyes lost 1 line of UCVA, and 3 eyes maintained the preoperative UCVA, whereas the rest (28 eyes) experienced a 1- to 10-line gain. The mean BCVA also improved from 0.47 +/- 0.31 (range, CF-1.0) to 0.64 +/- 0.26 (range, 0.1-1.0) (P <.01). Of 33 eyes, 4 eyes experienced 1- to 2-line loss of BCVA, 4 eyes maintained the preoperative BCVA, whereas the rest (25 eyes), experienced a 1- to 6-line gain. Of 3 patients (3 eyes) with unsatisfactory results, 1 patient improved with one segment removal and in 2 patients the segments were permanently removed. One of these eyes underwent successful PKP.

CONCLUSIONS

With mean follow-up of 11.3 months, intracorneal ring segments implantation improved UCVA and BCVA in the majority of the keratoconus patients. Even though the results are encouraging, concern still exists regarding the predictability as well as the long-term effect of such an approach for the management of keratoconus.

Ferrara intrastromal corneal rings for the correction of keratoconus

PURPOSE

To evaluate the safety and efficacy of Ferrara intrastromal corneal rings in the treatment of eyes with keratoconus without central corneal scarring.

SETTING

Vlemma Eye Institute, Athens, Greece.

METHODS

Twenty-six patients with bilateral keratoconus, clear central corneas, and contact lens intolerance participated in the study. Videokeratographic corneal topography and ultrasonic pachymetry were performed in all eyes to identify the cone area and to select the thickness of the segments to be implanted, respectively. Ferrara intrastromal corneal rings were implanted around the center of the cone in 1 eye of each patient.

RESULTS

The minimum follow-up after ring implantation was 6 months. In 2 cases, the rings had to be removed early in the postoperative period because of superficial implantation in 1 patient and asymmetrical placement in the other. The rest of the operated eyes demonstrated a reduction in astigmatism and spherical correction and improved uncorrected visual acuity. No eye lost best corrected visual acuity.

CONCLUSIONS

Ferrara intrastromal corneal rings reduced corneal steepening and normalized the central cornea in eyes with keratoconus. Ferrara ring implantation was a safe procedure that may be considered in patients who are unable to have other surgical techniques, particularly contact-lens-intolerant keratoconus patients whose only option is corneal transplantation.

Deep lamellar keratoplasty: surgical techniques for anterior lamellar keratoplasty with and without baring of Descemet's membrane

PURPOSE

To review current techniques used in deep anterior lamellar keratoplasty (LKP), and to describe a novel approach that facilitates baring of Descemet's membrane (maximum depth anterior lamellar keratoplasty).

METHODS

A highly selective review of the literature is presented, with descriptions of different techniques in the light of the authors' personal experience over 3 decades. A novel method for baring Descemet's membrane is detailed. It involves air injection in such a way that a large bubble is created between stroma and Descemet's membrane. Visual results of this operation in patients with keratoconus are reviewed.

RESULTS

Visual results 6 months after maximum depth anterior LKP in 181 eyes with keratoconus are comparable with those resulting from penetrating keratoplasty: 89% achieved a best spectacle-corrected visual acuity of 20/40 or better, and 10% achieved 20/20 or better. Intraoperative perforation occurred in 9% of cases.

CONCLUSIONS

Maximum depth anterior LKP has some important advantages when compared with other types of anterior lamellar keratoplasty or penetrating keratoplasty, but it remains a challenging procedure. A new technique considerably facilitates this operation and reduces intraoperative complications.

Laser in situ keratomileusis to correct myopia, hypermetropia and astigmatism after penetrating keratoplasty for keratoconus: a series of 27 cases

BACKGROUND

Excimer laser treatment has been shown to be effective and safe in correcting anisometropia following penetrating keratoplasty (PKP). In this report we review our experience with excimer laser in situ keratomileusis (LASIK) to correct refractive myopia, hypermetropia and astigmatism in patients who had undergone PKP for keratoconus.

METHODS

We reviewed the records of 22 patients (27 eyes) who had undergone LASIK to correct myopia, hypermetropia or astigmatism, in simple or combined forms, following corneal transplantation for keratoconus. LASIK was performed at a hospital in Curitiba, Brazil, between September 1998 and February 2000. The eyes were classified into two groups: those with a negative spherical equivalent and those with a positive spherical equivalent. LASIK was performed using the Moria LSK microkeratome and the Nidek EC-5000 excimer laser.

RESULTS

The mean length of follow-up was 9.52 months for the 23 eyes with myopia and 5.75 months for the 4 eyes with hypermetropia. The mean refractive spherical equivalent in the myopic eyes was -5.27 (standard deviation [SD] 1.91) dioptres before LASIK and -0.45 D (SD 1.68 D) at the last follow-up visit. The corresponding values in the eyes with hypermetropia were +5.18 D (SD 1.46 D) and + 1.18 D (SD 0.94 D). The rate of regression of astigmatism in the myopic eyes was 76%. After surgery 18 (78%) of the myopic eyes and all the hypermetropic eyes had an uncorrected visual acuity of 20/40 or better. The best spectacle-corrected visual acuity was better than 20/25 in 22 (95.7%) of the myopic eyes and all the hypermetropic eyes. One eye lost 1 line of best spectacle-corrected Snellen visual acuity, and one eye lost 6 lines secondary to epithelial ingrowth. Wound dehiscence, intraoperative flap complications, graft rejection or other complications did not develop in this series.

INTERPRETATION

In this series, LASIK proved to be relatively safe and effective in correcting refractive errors after PKP for keratoconus.