Outcomes of deep anterior lamellar keratoplasty using the big-bubble technique in various corneal diseases

Tomographic and topographic predictive factors of big bubble formation during deep anterior lamellar keratoplasty in keratoconus

PURPOSE

To identify preoperative predictors of big bubble (BB) formation during deep anterior lamellar keratoplasty (DALK) in patients with keratoconus (KC).

METHODS

DESIGN: Retrospective cohort study in an Italian tertiary centre.

STUDY POPULATION

Consecutive patients with KC undergoing DALK from January 2021 to July 2023.

OBSERVATION PROCEDURE

Tomographic and topographic data including K-max, K-mean, keratometric astigmatism, thinnest point, mean peripheral corneal thickness, difference between the mean peripheral corneal thickness and the thinnest point (peripheral-minimal corneal thickness), position (central/paracentral) and cone area (%), Amsler-Krumeich classification and anterior segment optical coherence tomography (AS-OCT) analysis to assess the severity stage.

MAIN OUTCOME MEASURES

Rate of BB formation and type; multivariate logistic regression analysis was used to analyse all preoperative parameters in patients with BB formation versus failure.

RESULTS

Pneumatic dissection succeeded in 98 of 140 eyes (70.0%), with 94 type 1 bubbles (67.1%) and four type 2 bubbles (2.9%). BB formation succeeded more frequently in patients with lower K-max (p=0.032), lower K-mean (p=0.010), higher thinnest point (p=0.017), lower peripheral-minimal corneal thickness (p=0.009) and lower Amsler-Krumeich stages (p=0.021). According to the AS-OCT analysis, BB formation was more frequent in the lower stages (p<0.001). After the logistic regression (pseudo-R²=0.176, constant=3.21, 95% CI 1.14 to 5.29, p=0.002), AS-OCT classification was found to be the only factor that predicted BB formation (coefficient=-0.81, 95% CI -1.18 to -0.43, p<0.001).

CONCLUSIONS

AS-OCT classification is a reliable predictor for BB formation. Tomographic and topographic analyses indicated that a steeper and more ectatic cornea is more prone to BB failure.

Influence of Opacity Depth on Big Bubble Formation During Deep Anterior Lamellar Keratoplasty in Corneal Stromal Scars

PURPOSE

To identify the key preoperative predictors of big bubble (BB) formation during deep anterior lamellar keratoplasty in patients with corneal stromal scars (CSS).

METHODS

This retrospective cohort study included consecutive patients with CSS after infective keratitis who underwent BB-deep anterior lamellar keratoplasty between January 2021 and July 2023 at a tertiary referral center. Topographic and tomographic data were collected to compare the rates and types of BB formations. Anterior segment optical coherence tomography (AS-OCT) was employed to assess the maximum depth of opacity by dividing the stroma into 3 zones of equal thickness: anterior (stage A), mid (stage B), and posterior stroma (stage C). Multivariate logistic regression analysis was performed to identify the potential preoperative predictors of bubble formation.

RESULTS

Pneumatic dissection was achieved in 13 of 33 eyes (39.4%), with 11 BB type 1 eyes (33.3%) and 2 BB type 2 eyes (6.1%). According to AS-OCT grading, bubble formation was more frequent with CSS involving more superficial stromal layers (P <0.032). In the eyes with stage C, bubble formation failed 12 out of 14 times (85.7%, P <0.026). Spearman correlation showed that bubble formation was inversely associated with the AS-OCT grading (rho = -0.443, P = 0.001). After logistic regression analysis, AS-OCT grading was found to be the sole factor that predicted bubble formation (coeff. -1.58, confidence interval 95% -3.03 to -0.12, P = 0.034).

CONCLUSIONS

Depth of opacity in CSS was the key determinant for predicting the success of pneumatic dissection, as advanced AS-OCT stages are strongly associated with BB failure.

Double-Docking Technique for Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty: A Retrospective Consecutive Case Series Study of Advanced Keratoconus

PURPOSE

The aim of this study was to report the clinical outcomes and prognosis of femtosecond laser (FSL)-assisted double-docking deep anterior lamellar keratoplasty (DD-DALK) for advanced keratoconus (AK).

METHODS

Records of consecutive patients with keratoconus who underwent FSL-assisted DALK (DD-DALK) were reviewed.

RESULTS

We analyzed 37 eyes from 37 patients who underwent DD-DALK. Sixty-eight percent of eyes had a successful big-bubble formation and 27% had a manual dissection to achieve the DALK deep dissection. Stromal scarring was associated with not achieving a big bubble. Intraoperative conversion to penetrating keratoplasty was conducted in 2 cases (5%). The best-corrected visual acuity improved from a median (± interquartile range) of 1.55 ±0.25 logMAR preoperatively to 0.2 ±0.2 logMAR ( P < 0.0001). The median postoperative spherical equivalent was -5.75 ±2.75 D with a median astigmatism of -3.5 ±1.3 D. BCVA, SE, and astigmatism were not statistically different between patients who underwent DD-DALK and patients who underwent manual DALK. Stromal scarring was associated with big-bubble (BB) formation failure ( P = 0.003). All patients with failed BB requiring manual dissection had anterior stromal scarring.

CONCLUSIONS

DD-DALK is safe and reproducible. The success rate of BB formation is hampered by stromal scarring.

Comparison of visual outcomes, keratometric parameters and biomechanical profiles between deep anterior lamellar keratoplasty with big-bubble technique vs. Melles technique for keratoconus: a retrospective study

OBJECTIVE

Comparing results of two different DALK surgery techniques (big bubble vs. Melles) in patients with advanced keratoconus.

DESIGN

a retrospective comparative clinical study.

PARTICIPANTS

This study conducted on 72 eyes of 72 participants.

INTRODUCTION

This study designed to compare the results of two different DALK surgery techniques (big bubble vs. Melles) in patients with advanced keratoconus.

METHOD

Thirty-seven eyes were treated using the big bubble DALK method, while 35 eyes were treated using the Melles approach. Uncorrected visual acuity (UCVA), best corrected spectacle visual acuity (BCSVA), manifest refraction, keratometric characteristics, contrast sensitivity, corneal aberrations, corneal biomechanical characteristics, and endothelial cell profile are the outcome measurements.

RESULTS

Mean UCVA in big bubble group was 0.61 ± 25 LogMAR and in Melles group was 0.89 ± 0.41 LogMAR (p-value 0.043). Mean BCSVA in big bubble group (0.18 ± 0.12 Log MAR) was significantly better than Melles group (0.35 ± 0.16 Log MAR). Mean of sphere and cylinder refraction showed no significant difference between two groups. Comparing the endothelial cell profile, corneal aberrations, corneal biomechanical properties and keratometry had no significantdifferences. Contrast sensitivity reported as modulation transfer function (MTF) showed higher values in big bubble group and differences with Melles group weresignificant. Results of point spread function (PSF) in big bubble group had superiority to Melles group with considerable statistical P value of 0.023.

CONCLUSION

When opposed to the Melles approach, the big bubble technique generates a smooth interface with less stromal residue, which results in higher visual quality and contrast sensitivity.

Impact of cone base diameter on outcomes of deep anterior lamellar keratoplasty in keratoconus

PURPOSE

To evaluate the outcomes of deep anterior lamellar keratoplasty (DALK) in treating keratoconus in relation to cone base diameter (CBD).

METHODS

A retrospective study. Sixty-one eyes of 49 keratoconus patients who underwent DALK between 2009 and 2018 were enrolled. Preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent, and astigmatism were measured. Scheimpflug tomography (Pentacam) was used to measure the cone base area (CBA) and CBD using MATLAB software.

RESULTS

The mean age of the patients was 20.8 ± 6.1 years old, and the mean follow-up time was 27.3 ± 15.2 months. Mean UCVA improved from 1.23 ± 0.48 to 0.57 ± 0.27 (LogMAR, 95% CI [0.52, 0.80]; P < 0.001), whereas mean BCVA improved from 0.98 ± 0.55 to 0.18 ± 0.13 (95% CI [0.66, 0.94]; P < 0.001). The mean spherical equivalent decreased by 4.53 ± 5.65 D (95% CI [- 6.25, - 2.82]; P < 0.001), with little change in astigmatism (95% CI [- 1.39, 0.64]; P = 0.457). The postoperative BCVA in the patients with CBD < 5.07 mm and corneal curvature ≥ 55D was significantly better than those whose CBD ≥ 5.07 mm (0.14 ± 0.09 vs 0.25 ± 0.15, P = 0.001). The follow-up time was negatively correlated with the BCVA (P = 0.004).

CONCLUSIONS

In this study, outcomes of DALK in keratoconus were related to CBD and corneal curvature. Patients with large CBD (≥ 5.07 mm) where the corneal curvature ≥ 55D are more likely to have poor visual outcomes after DALK.

An Overview of Intraoperative OCT-Assisted Lamellar Corneal Transplants: A Game Changer?

Intraoperative optical coherence tomography (iOCT) is a noninvasive imaging technique that gives real-time dynamic feedback on surgical procedures. iOCT was first employed in vitreoretinal surgery, but successively served as a guidance in several anterior segment surgical approaches: keratoplasty, implantable Collamer lens (ICL) implantation, and cataract surgery. Among all of those approaches, the unbeatable features of iOCT are fully exploited in anterior and posterior lamellar keratoplasty, and the purpose of this review is to focus on the advantages and shortfalls of iOCT in these techniques, in order to assess whether this technology could be a real step forward. In deep anterior lamellar keratoplasty (DALK), iOCT is useful to evaluate the needle depth into the corneal stroma, the big bubble dissection plane, and residual stromal bed, thus aiding the standardization of the technique and the reduction of failures. In Descemet stripping automated endothelial keratoplasty (DSAEK), iOCT allowed for clear visibility of fluid at the graft/host interface, allowing for immediate rescue maneuvers and granting the best graft apposition. In Descemet membrane endothelial keratoplasty (DMEK), iOCT can track the lenticule unfolding in real time and assess graft orientation even in severe hazy corneas, thus optimizing surgical times, as well as avoiding the use of potentially hazardous exterior markers (such as the “S” stamp) and preventing unnecessary manipulation of the graft. Overall, the role of iOCT appeared crucial in several complicated cases, overcoming the difficulties of poor visualization in a fast, non-invasive way, thus raising this approach as possible gold standard for challenging conditions. Further improvements in the technology may enable autonomous centering and tracking, overcoming the current constraint of instrument-induced shadowing.

A New Pre-descemetic Corneal Ring (Neoring) in Deep Anterior Lamellar Keratoplasty for Moderate-Advanced Keratoconus: A Pilot 2-Year Long-Term Follow-Up Study

Purpose: To assess the outcomes of implanting a new polymethylmethacrylate (PMMA) ring (Neoring; AJL Ophthalmic) in pre-descemet deep anterior lamellar keratoplasty (PD-DALK) procedure for moderate-advanced keratoconus.

Methods: This prospective study included 10 eyes of 10 patients with moderate-advanced keratoconus who underwent PD-DALK with Neoring implantation. Neoring was implanted in a pre-descemetic pocket. The post-operative examination included refraction, corrected distance visual acuity (CDVA), corneal tomography, and endothelial cell density (ECD). The root mean squares (RMSs) for coma-like aberrations and spherical aberration were evaluated for a pupil size of 4.5 mm. The junctional graft (Tg) and host (Th) thicknesses were measured. The post-operative follow-up was 24 months.

Results: Post-operative CDVA was 0.82 ± 0.14 (decimal scale), 100% of the eyes achieved a CDVA of 0.7 (decimal scale). The refractive cylinder was −2.86 ± 1.65 2-years after surgery. No eyes had a post-operative refractive cylinder ≥5.00 D and in five eyes (50%), it was ≤2.50 D. At the last visit, the mean keratometry was 45.64 ± 1.96 D, the RMS for coma-like aberrations was 0.30 ± 0.15 μm and spherical aberration was 0.22 ± 0.09. The mean ECD remains without changes over the follow-up (P = 0.07). At the last visit, Tg and Th were 679.9 ± 39.0 and 634.8 ± 41.2 μm, respectively. The thickness of the complex (host-Neoring) was 740.6 ± 35.6 μm. In all cases, this thickness was thicker than Tg.

Conclusion: The results of this study suggest that PD-DALK along Neoring implantation is a viable, effective, and safe option to optimize the post-operative results for moderate-severe keratoconus.

Survey report on keratoplasty in China: A 5-year review from 2014 to 2018

To provide the general information on corneal transplantation (CT) in China, China Cornea Society designed a questionnaire on CT from 2014 to 2018 and entrusted it to 31 committee members for implementation of the survey nationwide. This article presents the results of the survey and compares the indicators used in the survey and those in the annual statistical report released by the Eye Bank Association of America (EBAA). The number of corneal transplantations completed by the 64 hospitals from 2014 to 2018 was respectively 5377, 6394, 7595, 8270 and 8980, totally 36,616 (22,959 male and 13,657 female). The five largest hospitals by the number of corneal transplantations completed 15,994 surgeries in total, accounting for 43.68% of all the surgeries performed in the 64 hospitals. The most common indication for corneal transplantations was corneal leukoma (7683, 20.98%), followed by bacterial keratitis (4209, 11.49%), corneal dystrophies (4189, 11.44%), keratoconus (3578, 9.77%) and corneal perforation (2839, 7.75%). The main surgical techniques were penetrating keratoplasty (PK) (19,896, 54.34%), anterior lamellar keratoplasty (ALK) (13,869, 37.88%). The proportion of PK decreased from 57.97% in 2014 to 52.88% in 2018 while the proportion of ALK increased from 36.04% in 2014 to 37.92% in 2018. The geographical distribution of keratoplasties performed in China is unbalanced. PK and ALK were the main techniques of CT and corneal leukoma, bacterial keratitis and corneal dystrophies were the main indications for CT in China.

Approaches toward enhancing survival probability following deep anterior lamellar keratoplasty

The greatest advantage of deep anterior lamellar keratoplasty over full-thickness corneal transplantation is the elimination of graft failure caused by endothelial rejection. Despite this advantage, a deep anterior lamellar keratoplasty graft can fail because of several factors, such as complications related to the donor-recipient interface, graft epithelial abnormalities, graft vascularization, stromal graft rejection, and recurrence of herpetic keratitis. Increased deep anterior lamellar keratoplasty graft survival is mainly built upon optimization of the ocular surface to provide a hospitable environment for the graft. Any predisposing factors for graft epithelial abnormalities, corneal neovascularization, and preexisting vernal keratoconjunctivitis should be identified and treated preoperatively. Prompt recognition and appropriate treatment of interface-related complications and stromal graft rejection usually result in good anatomic outcomes, with no detrimental effects on vision.

Clinical Properties and Risk Factors for Descemet Membrane Folds After Deep Anterior Lamellar Keratoplasty in Patients With Keratoconus

PURPOSE

To report the clinical properties and risk factors for corneal Descemet membrane (DM) folds after deep anterior lamellar keratoplasty (DALK) in patients with keratoconus.

METHODS

This is a retrospective case-control study. Study participants-experimental group: 44 eyes with DM folds after DALK; control group: 135 eyes without DM folds after DALK.

RESULTS

Forty eyes with DM folds were displayed as 1 or 2 translucent lines in the DM layer. Three eyes appeared as several arcuate shape lines, and 1 eye presented as a radial shape. DM folds impaired corrected visual acuity after DALK (P = 0.018). Age older than 20.5 years at surgery and disease duration longer than 5.5 years were independent risk factors for DM fold formation after DALK surgery (odds ratio 5.39, 95% confidence interval: 2.11-13.73, P < 0.001; 6.60, 95% confidence interval: 2.92-14.94, P < 0.001). Preoperative Kmean, Kmax, central corneal thickness, anterior chamber depth, sex, history of rigid gas permeable contact lens wearing, Vogt striae, stromal scar, and intraoperative microperforation had no influence on the occurrence of DM folds (P1 = 0.775, P2 = 0.896, P3 = 0.555, P4 = 0.182, P5 = 0.656, P6 = 0.237, P7 = 1.000, P8 = 0.587, and P9 = 0.798).

CONCLUSIONS

DM folds impaired postoperative corrected visual acuity. The risk factors for DM folds included age older than 20.5 years and disease duration longer than 5.5 years.

Effect of Keratoconus Severity on Clinical Outcomes After Deep Anterior Lamellar Keratoplasty

PURPOSE

To evaluate the effect of keratoconus severity on the visual and refractive outcomes and complications after deep anterior lamellar keratoplasty (DALK).

DESIGN

Consecutive interventional case series.

METHODS

This study enrolled 227 keratoconus-affected eyes that underwent DALK. Amsler-Krumeich keratoconus classification was used to categorize the patients: stage II, 47 eyes; stage III, 60 eyes; and stage IV, 120 eyes. The outcome measures, including postoperative best spectacle-corrected visual acuity (BSCVA), spherical equivalent refraction, mean keratometry, keratometric astigmatism, and complications, were analyzed and compared based on keratoconus stage.

RESULTS

The mean patient age was 27.6 ± 8.0 years, and the mean follow-up period was 38.0 ± 19.8 months. No significant differences were observed in postoperative BSCVA (P = .55), spherical equivalent refraction (P = .27), mean keratometry (P = .09), and keratometric astigmatism (P = .14) among the groups. Improvement in BSCVA were significantly greater in stage III and stage IV compared with stage II (P = .04 and P < .001, respectively). The decrease in spherical equivalent was significantly greater in stages III and IV compared with stage II (P = .04 and P = .001, respectively). Mean keratometry decreased to a greater degree in stage IV compared with stages II and III (P < .001 for both comparisons). The study groups were comparable with respect to intraoperative Descemet membrane perforation, the rate of successful big-bubble formation, suture-related complications, and graft rejection.

CONCLUSIONS

DALK is a safe and effective procedure for the treatment of all stages of keratoconus. This technique of corneal transplantation is more effective in eyes with severe keratoconus compared with those with moderate keratoconus.

Intraoperative Optical Coherence Tomography-Guided Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty

PURPOSE

To describe the feasibility and outcomes of intraoperative optical coherence tomography (OCT)-guided, femtosecond laser-assisted deep anterior lamellar keratoplasty in which the lamellar and tunnel cuts were completed by laser.

METHODS

The Ziemer Z8 system was used to scan the corneas intraoperatively and guide the stromal lamellar and tunnel cuts created by the laser. Thirty porcine eyes and 3 human cadaver globes were used to evaluate the accuracy of laser-created intrastromal tunnels and the feasibility of achieving big-bubble pneumatic dissection. The tunnel distance above the Descemet membrane (Dt-dm) was set at 100 and 130 μm, and the accuracy of laser cut was assessed by anterior segment OCT and histological sections. Fourteen patients with keratoconus or corneal scars were then included to evaluate the clinical outcomes.

RESULTS

The deviation from the targeted Dt-dm was 5.5% to 8.6% and 0.7% to 9.8% for the 100 and 130 μm groups, respectively. The achieved thickness had a significantly and positively strong correlation with the targeted thickness (r = 0.86; P < 0.001). In all cases, the anterior stromal lamella was removed without difficulty, except in the patients with corneal scars in whom some remaining stromal fiber attachments were observed. A type 1 big bubble was successfully achieved in all patients.

CONCLUSIONS

We present the accuracy and clinical outcomes of femtosecond laser-assisted, intraoperative OCT-guided deep anterior lamellar keratoplasty, in which controlled lamellar and tunnel cuts at desired depths were performed by laser in one step, and a successful big bubble was achieved.

Immunologic Stromal Rejection After Deep Anterior Lamellar Keratoplasty With Grafts of a Larger Size (9 mm) for Various Stromal Diseases

PURPOSE

To evaluate the rate and outcomes of immunologic stromal rejection occurring after large deep anterior lamellar keratoplasty (DALK) and the effect of the underlying disease on the cumulative probability of rejection.

METHODS

This was a retrospective chart review of all eyes that underwent a 9-mm DALK at Ospedali Privati Forlì (Forlì, Italy). On the basis of preoperative diagnosis, eyes were assigned to group 1: keratoconus, group 2: stromal disease with a low risk for rejection, or group 3: stromal disease with a high risk for rejection. The cumulative probability of experiencing a rejection episode over time was assessed by Kaplan-Meier analysis and was compared among the 3 groups using the log-rank test. Values of corrected distance visual acuity, central corneal thickness, and endothelial cell density before and 6 months after rejection were compared.

RESULTS

Twenty of 377 eyes (5.3%) experienced an episode of stromal rejection [17/265 (6.4%) in group 1, 2/71 (2.8%) in group 2, and 1/41 (2.4%) in group 3]. The mean time interval between DALK and the rejection onset was 11.8 months (range 1-24). The cumulative probability of rejection episodes did not differ significantly among the 3 groups. All episodes resolved within 6 months after the onset, with no significant differences between prerejection and 6-month postrejection values of corrected distance visual acuity, central corneal thickness, and endothelial cell density.

CONCLUSIONS

The rate of immunologic stromal rejection after large 9-mm DALK is within the range reported in the literature for conventional DALK, regardless of the indication for surgery.

Femtosecond laser-assisted deep anterior lamellar keratoplasty in phototherapeutic keratectomy versus the big-bubble technique in keratoconus

AIM

To compare the functional and anatomic results of femtosecond laser (FSL)-assisted deep anterior lamellar keratoplasty (DALK) associated with phototherapeutic keratectomy (PTK) and FSL-assisted DALK performed using the big-bubble technique in keratoconus.

METHODS

During the first phase of the study, an electron microscopy histopathology pilot study was conducted that included four unsuitable donor corneas divided into two groups: in FSL group, FSL lamellar cuts were performed on two corneas and in FSL+PTK group, PTK was performed at the stromal beds of two corneas after FSL lamellar cuts were made. During the second phase of the study, a randomized clinical trial was conducted that included two treatment groups of patients with keratoconus: group 1 (n=14 eyes) underwent FSL-assisted DALK associated with PTK and group 2 (n=12 eyes) underwent FSL-assisted DALK associated with the big-bubble technique. The main outcome measures were the postoperative visual acuity (VA) and optical coherence tomography (OCT) measurements, confocal microscopic findings, and contrast sensitivity.

RESULTS

In the pilot study, histopathology showed a more regular stromal bed in the FSL+PTK group. In the clinical trial, group 1 had significantly worse best spectacle-corrected VA and contrast sensitivity (P<0.05 for both comparisons). The residual stromal bed measured by OCT was significantly (P<0.05) thicker in group 1. Confocal microscopy detected opacities only at the donor-receptor interface in group 1.

CONCLUSION

Patients with keratoconus treated with FSL-assisted DALK performed using the big-bubble technique fare better than treated with FSL-assisted DALK associated with PTK.

Femtosecond laser-assisted deep anterior lamellar keratoplasty with big-bubble technique for keratoconus

Purpose:

The purpose of this study was to evaluate the clinical results after deep anterior lamellar keratoplasty (DALK) assisted by the femtosecond laser with big-bubble technique for keratoconus.

Methods:

A case series of 22 eyes in 19 patients with keratoconus was enrolled in the study. The 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany) was used to create a vertical side cut on donor and recipient corneas. Intraoperative and postoperative complications, uncorrected visual acuity, best-corrected visual acuity, corneal curvature, and central corneal thickness were evaluated in all patients.

Results:

Big-bubble and naked Descemet's membrane (DM) were successfully achieved in twenty eyes (90.9%). Intraoperative macroperforation of DM occurred in two cases and converted to full-thickness keratoplasty. The mean follow-up time was 18.8 ± 5.3 months. The best-corrected visual acuity was increased from 0.3 to 1.0, mean corneal curvature was 43.0 ± 2.3D, and mean central corneal thickness was 508.9 ± 60.1 μm (range, from 430 to 600 μm) postoperatively.

Conclusion:

Our results indicate that femtosecond laser-assisted DALK with big-bubble technique is an accurate, safe, and effective method to treat the patients with keratoconus.

Surgical outcome of deep anterior lamellar keratoplasty with air-assisted manual dissection for corneas with previous inflammation or fibrosis

PURPOSE:

To report our experience in air-assisted manual dissection deep anterior lamellar keratoplasty (DALK) for the treatment of corneal scar with previous inflammation and fibrosis.

MATERIALS AND METHODS:

We retrospectively reviewed the medical history of 21 patients (male:female = 13:8 mean age 41.9 years old) with corneal pathology from previous infection and inflammation. Trephination diameter ranged from 7.0 to 8.0 mm, and the graft was oversized by 0.25–0.50 mm. Debulking technique was performed to expose Descemet's membrane after filling stroma with air. Starting from postoperative 3 months, selective suture removal was performed to reduce corneal astigmatism.

RESULTS:

The mean follow-up period was 59.9 ± 19.8 (20–96) months. Intraoperative microperforation occurred in 2 eyes (9.5%); however, there was no shift to penetrating keratoplasty. Air-bubble tamponade was performed in 7 eyes (33.3%) for postoperative gapping of the graft. There were 2 failed grafts (9.5%) due to corneal ulcer while all the other grafts remained clear throughout follow-up. The mean preoperative best-corrected visual acuity (BCVA) was 1.84 ± 0.66 logMAR, which improved to 0.74 ± 0.63 (P < 0.01). The average sphere power was − 0.88 ± 3.88 diopter (D), average cylinder power 3.03 ± 1.46D, and average endothelial count 1877 ± 375 cells/mm².

CONCLUSION:

In severe ocular surface diseases, big-bubble technique frequently failed to separate predescemtic plane; however, it effectively created air-filled stroma which was easier to remove. Although BCVA was suboptimal due to ocular surface disorders, graft survival and clarity rate is high, justifying the application of DALK in these cases.

Outcomes of Same-Size Host and Donor Trephine in Deep Anterior Lamellar Keratoplasty for Keratoconus

PURPOSE

To evaluate the efficacy of the same-size host and donor trephine on reducing myopic refractive errors for patients with keratoconus when deep anterior lamellar keratoplasty (DALK) was used.

DESIGN

Randomized controlled clinical trial.

METHODS

One hundred eighteen eyes of 118 patients with keratoconus were enrolled. Using stratified blocked randomization, eligible eyes were allocated into the same-size trephine group or oversize trephine group. Postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), spherical equivalent (SE), topography data, and eye axial length were compared at each year for 5 years.

RESULTS

The same-size trephine group had comparable UCVA to the oversize trephine group through 5 years after surgery. But the former had better BSCVA than the latter after 3 years of follow-up. At 5 years, mean BSCVA was 0.17 ± 0.10 logMAR in the same-size trephine group vs 0.25 ± 0.13 logMAR in the oversize trephine group (P = .03). The same-size trephine group had lower topographic power than the oversize trephine group after 3 years of follow-up. At 5 years, mean topographic power was 45.30 ± 2.28 diopters (D) in the same-size trephine group vs 46.75 ± 2.60 D in the oversize trephine group (P = .006). Eye axial lengths at 5 years were longer than those preoperatively as well as at 1 year follow-up after surgery in both groups.

CONCLUSIONS

The same-size host and donor trephine could reduce late-stage myopic refractive errors for the patients with keratoconus after DALK. The mechanism may be late-stage axial length increase with time.

Morphometric changes of corneal endothelial cells following intracameral air for micro perforation of the Descemet Membrane during big-bubble deep anterior lamellar keratoplasty

Aim

The aim of this study was to assess the effect of intracameral air on the endothelial cell morphometrics.

Patients and methods

This is a retrospective controlled interventional cohort study of 26 patients (18 males and 8 females) who underwent unilateral deep anterior lamellar keratoplasty (DALK) for moderate keratoconus. The DALK patients were divided into two groups: a treatment group (14), which had micro perforations of the Descemet Membrane (DM) intraoperatively and received intracameral air at the end of the surgery; and an independent control group (12), which had no micro perforation and thus no intracameral air was injected. Postoperative best corrected visual acuity (BCVA), sphere, cylinder, spherical equivalent (SEQ), central corneal thickness, and endothelial cell morphometric features consisted of the endothelial cell density (ECD), polymegathism, and pleomorphism were compared between treatment and control groups.

Results

The mean BCVA was 0.36 ± 0.36 logMAR in the treatment group and 0.17 ± 0.11 logMAR in the control group (p = 0.081), and the mean corneal thickness was 507.86 ± 62.69 μm in the treatment group and 525.67 ± 37.54 μm in the control group air (p = 0.399). Furthermore, the mean sphere was −5.14 ± 4.17D and −1.02 ± 3.29D, the mean cylinder was −3.16 ± 2.20D and −2.88 ± 1.21D, and the mean SEQ was −6.72 ± 4.66D and −2.46 ± 3.14D and in the treatment and control groups respectively (p = 0.011, 0.693, and 0.013). As to morphometric features, the mean ECD was 2176.76 ± 549.18 cell/mm² and 2257.30 ± 436.12 cell/mm² in the treatment and control groups respectively (p = 0.686), and the mean pleomorphism 0.48 ± 0.09 and 0.54 ± 0.10 in the treatment and control groups respectively (p = 0.139). In contrast, the mean polymegathism was 0.37 ± 0.06 and 0.31 ± 0.05 in the treatment and control groups respectively (p = 0.009).

Conclusion

The presence of air inside the anterior chamber for a short term may not cause further endothelial cell loss and can be safely performed to prevent postoperative Descemet Membrane detachment in case of micro perforations.

Comparison of femtosecond laser-assisted deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus

BACKGROUND

To compare outcomes of femtosecond laser-assisted deep anterior lamellar keratoplasty (FSL-DALK) and penetrating keratoplasty (FSL-PK) for the treatment of keratoconus.

METHODS

Twenty eight eyes underwent FSL-DALK (consisted of 12 eyes in the FSL-DALKa subgroup without baring the Descemet's membrane and 16 eyes in the FSL-DALKb subgroup baring the Descemet's membrane using big-bubble technique) were compared with 12 eyes that underwent FSL-PK for keratoconus. These patients underwent an ophthalmic examination preoperatively and 3, 6, 9, and 12 months postoperatively.

RESULTS

The postoperative BCVA in the FSL-PK group, and the FSL-DALKb subgroup were significantly better than that in the FSL-DALKa subgroup (P < 0.05), whereas no differences were found between the FSL-DALKb subgroup and the FSL-PK group (P > 0.05). There were no significant differences in the mean spherical equivalent (SE) and astigmatism between the FSL-DALK and the FSL-PK groups, nor between the subgroups of FSL-DALK during the follow-up period (P > 0.05). At the last follow-up, the mean endothelial cell loss in the FSL-DALK group (9.12 %) was significantly less than that in the FSL-PK group (20.79 %) (P < 0.001), while there was no difference between the FSL-DALKa (9.15 %) and the FSL-DALKb (9.10 %) subgroups (P = 0.15). The FSL-DALK group seemed to have fewer graft rejections (1/28 cases) than the FSL-PK group (2/12 cases), although Kaplan-Meier curve showed no significant difference between the two groups (P = 0.144).

CONCLUSIONS

In this retrospective study, the results suggested that FSL-DALKb gives better visual outcome, and FSL-DALKb is a better option for keratoconus whose endothelium is not compromised. However, larger and prospective studies are further required.

Factors influencing big-bubble formation during deep anterior lamellar keratoplasty in keratoconus

PURPOSE

To investigate recipient and operative factors that can influence the rate of achieving a bare Descemet's membrane (DM) during deep anterior lamellar keratoplasty (DALK) for keratoconus.

MATERIALS

In this retrospective comparative study, a total of 290 (153 right) consecutive eyes from 257 (179 male) keratoconus-affected patients who underwent DALK with the big-bubble technique were enrolled. Univariate analyses and multiple logistic regressions were used to investigate factors including patient age and sex, family history of keratoconus, history of contact lens wear or vernal keratoconjunctivitis, the presence of Vogt's striae or superficial stromal opacities, keratometric readings, corneal diameter, central and peripheral corneal thickness, anterior chamber depth, vitreous length, and trephination size, which could predict achievement of a bare DM.

RESULTS

The surgery was completed as a DALK in 289 of 290 eyes, and a bare DM was successfully achieved in 229 (79.2%) eyes. The recipient sex and trephination size significantly influenced the success rate of big-bubble formation. Females had decreased odds of achieving a bare DM by 0.44 times (p=0.02). For each 0.1 mm increase in the trephination size, the odds of a successful big-bubble formation increased by 1.36 times (p=0.03). Other investigated factors did not significantly influence the rate of achieving a bare DM.

CONCLUSIONS

The rate of successful big-bubble formation was 79.2% in keratoconus. Among the different factors, recipient sex and trephination size significantly influenced this rate. Females had a lower probability of big-bubble formation, and a large trephination size was associated with an increase in the probability of achieving a bare DM.

Comparison of refractive outcomes in three corneal transplantation techniques for keratoconus

BACKGROUND

Deep anterior lamellar keratoplasty (DALK) has a much lower incidence of immunologic reactions than penetrating keratoplasty (PK) for patients with keratoconus. However, it is unclear whether DALK is better on refractive outcomes than PK, due to its high postoperative myopia.

METHODS

We retrospectively studied the clinical records of keratoconus patients who underwent PK, DALK, or predescemetic DALK (pre-DALK, DALK with residual stroma) between June 2004 and September 2008. The main outcome measures included refractive sphere, manifest cylinder, corneal power, keratometric astigmatism, and best-corrected visual acuity (BCVA) at the latest visit and the methods of visual correction. Postoperative manifest refractions and topography data were compared at postoperative 3, 5, 7, and 9 years among the three groups. Additionally, the final BCVA and the methods of vision correction were compared.

RESULTS

A total of 172 subjects (172 eyes) screened out of 207 keratoconus patients underwent PK (79 eyes), DALK (68 eyes), or pre-DALK (25 eyes). Postoperative myopic refractive sphere increased in all groups, but the most obvious increase was noted in the pre-DALK group. At the 9-year follow-up, both the pre-DALK group (-6.5 ± 1.7 D) and DALK group (-6.1 ± 1.8 D) had higher myopic refractive sphere than the PK group (-5.0 ± 1.5 D, p < 0.05). Postoperative myopic manifest astigmatism progressively increased in 5 years, but there were no differences among the groups. The progressive increases in postoperative corneal power were recorded in all groups, with the highest one in the pre-DALK group and the lowest in the PK group. At the 9-year follow-up, both the pre-DALK (49.8 ± 2.7 D) and DALK (48.8 ± 2.1 D) groups had higher corneal power than the PK group (47.3 ± 2.0 D); meanwhile, the corneal power was higher in the pre-DALK group than the DALK group (p < 0.05). No differences were noted with respect to keratometric astigmatism among the groups. Mean LogMAR BCVA was 0.12 ± 0.12 in the DALK group, 0.17 ± 0.10 in the pre-DALK group, and 0.1 ± 0.11 in the PK group (p = 0.325) at 9 years after surgery. Moreover, the methods of achieving BCVA seem to be similar among the treatment groups.

CONCLUSIONS

Although DALK has a slightly higher degree of myopic refraction than PK, DALK and PK have comparable visual acuity outcomes and similar methods of vision correction. DALK is recommended for the treatment of keratoconus.

Big bubble deep anterior lamellar keratoplasty for management of deep fungal keratitis

Objective. To evaluate the therapeutic effect of big bubble deep anterior lamellar keratoplasty (DALK) in patients with deep fungal keratitis. Methods.Consecutive patients who had DALK for deep fungal keratitis at Shandong Eye Hospital between July 2011 and December 2012 were included. In all patients, the infiltration depth was more than 4/5ths of the corneal thickness. DALK surgery was performed with bare Descemet membrane (DM) using the big bubble technique. Corrected distance visual acuity (CDVA), graft status, and intraoperative and postoperative complications were monitored. Results. Big bubble DALK was performed in 23 patients (23 eyes). Intraoperative perforation of the DM occurred in two eyes (8.7%) during stromal dissection. The patients received lamellar keratoplasty with an air bubble injected into the anterior chamber. Double anterior chamber formed in 3 eyes (13.0%). Mean CDVA of the patients without cataract, amblyopia, and fungal recurrence was improved from preoperative HM/20 cm−1.0 (LogMAR) to 0.23 ± 0.13 (LogMAR) at the last followup (P < 0.01). Fungal recurrence was found in two patients (8.7%). Corneal stromal graft rejection was noted in one patient (4.3%). Conclusions. DALK using the big bubble technique seems to be effective and safe in the treatment of deep fungal keratitis unresponsive to medication.

Deep anterior lamellar keratoplasty with a manual spatula: anatomical and functional results

Objective:

Evaluate the anatomical, refractive, and functional results of an innovative technique of deep anterior lamellar keratoplasty with a manual spatula.

Materials and Methods:

We evaluated the results and examinations of 16 eyes from 14 patients who underwent deep anterior lamellar keratoplasty using the technique described by Ferrara. Residual bed thickness after keratoplasty was evaluated postoperatively using Visante. The measurement was performed using a technique similar to that used to measure flap thickness after laser in situ keratomileusis refractive surgery. The measurements were performed at the center of the cornea in an area comprising the central 3-mm in the 45° and 135° meridians.

Results:

Best-corrected visual acuity was 0.34 ± 0.18 LogMar (0.09 to 0.60 LogMar), the spherical equivalent was -4.31 ± 3.38 D (+0.25 to -9.50 diopters), and keratometry was 45.75 ± 2.77 D (41.11 to 52.48 diopters) postoperatively. Corneal astigmatism was 3.19 ± 2.78 D (0.18 to 11.81 diopters). Residual stromal bed thickness measured by optical coherence tomography showed values of 67.1 ± 24.3 μm (30 to 109 μm). The statistical correlation by Spearman's test between the best-corrected visual acuity and the residual stromal bed thickness was 0.11 (P = 0.67).

Conclusion:

Deep anterior lamellar keratoplasty, in which manual dissection was performed using an instrument similar to that used to implant corneal rings, provided good visual and anatomical results.

One Year of Cornea Research in Review-2012

PURPOSE

The purpose of this study was to provide an update of significant cornea literature published in the past 1 year.

DESIGN

This was a literature review.

METHODS

The authors conducted a 1-year English-language literature search on PubMed, from January 1, 2012, to December 31, 2012, using the following terms: corneal transplantation, anterior lamellar keratoplasty, penetrating keratoplasty, endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty, Descemet membrane endothelial keratoplasty, Descemet membrane endothelial transfer, ocular surface epithelial transplantation, limbal epithelial transplantation, cultivated oral mucosal epithelial transplantation, keratoprosthesis, infectious keratitis, cross-linking, keratoconus, corneal neovascularization, corneal imaging, optical coherence tomography, Pentacam Scheimpflug imaging, and in vivo confocal microscopy.

RESULTS

This review includes original articles and review articles that contain significant updates and novel aspects in the field of cornea from the following journals: American Journal of Ophthalmology, British Journal of Ophthalmology, Ophthalmology, Investigative Ophthalmology and Visual Science, and Cornea. Letters to the editor, unpublished work, manuscripts not in English, and abstracts were not included.

CONCLUSIONS

This review highlights significant literature that is applicable to the practicing ophthalmologist.

Split cornea transplantation: relationship between storage time of split donor tissue and outcome

PURPOSE

To analyze the relationship between storage time of split donor tissue and outcomes after deep anterior lamellar keratoplasty (DALK) and Descemet's membrane endothelial keratoplasty (DMEK).

DESIGN

Retrospective analysis of a nonrandomized, consecutive, interventional case series.

PARTICIPANTS

One hundred ten eyes with anterior stromal disease suitable for DALK and 110 eyes with endothelial disease suitable for DMEK underwent surgically successful split cornea transplantation combining both procedures within 7 days after splitting.

METHODS

Split donor storage times (splitting to grafting) and total storage times (death to grafting) were correlated with the 1-year functional and morphologic outcomes after DALK and DMEK surgery using a Spearman correlation coefficient and a Mann-Whitney U test.

MAIN OUTCOME MEASURES

Best spectacle-corrected visual acuity (BSCVA), endothelial cell density, and complication rates within 12 months of follow-up.

RESULTS

The mean split donor storage time was 35 ± 47 hours (range, 0-162 hours) after splitting for anterior donor grafts and 21 ± 40 hours (range, 0-158 hours) for posterior grafts. The mean total storage time was 352 ± 108 hours (range, 108-678 hours) for anterior lamellas and 339 ± 109 hours (range, 96-630 hours) for posterior lamellas. One year after DALK, the mean BSCVA was 20/30 (range, 20/50-20/20), endothelial cell loss was 8% (range, 2%-16%), and the complication rate (Descemet's folds, epitheliopathy, loose sutures) was 18%. One year after DMEK, the mean BSCVA was 20/25 (range, 20/40-20/16), endothelial cell loss was 41% (range, 17%-63%), and the complication rate (partial graft detachment) was 62%. For DALK and DMEK, no significant association was observed between split donor storage time as well as total storage time and BSCVA (P ≥ 0.409), endothelial cell loss (P≥0.236), or complication rate (P ≥ 0.647) within 1 year of follow-up.

CONCLUSIONS

Anterior and posterior donor tissue may be stored safely for up to 1 week in organ culture before use in DALK and DMEK surgery. This simplifies the clinical feasibility of split cornea transplantation to reduce donor shortage and cost in corneal transplantation in the future.

FINANCIAL DISCLOSURE(S)

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