Outcomes of Repeat Anterior Lamellar Keratoplasty

In vivo confocal microscopy confirms the presence of new predescemetic cellular layer in post-penetrating keratoplasty buttons

BACKGROUND/AIM

To investigate the in vivo presence of a natural plane of separation at the pre-Descemet membrane (DM) level in post-penetrating keratoplasty (PK) eyes using confocal microscopy.

METHODS

In vivo confocal microscopy was performed on the corneal stroma of 20 post-PK eyes and 20 keratoplasty-naive healthy control eyes. Patients were recruited from the cornea service of Ospedali Privati Forlì 'Villa Igea' between June 2022 and February 2024. The study adhered to the Declaration of Helsinki and was approved by the local ethics committee. Main outcome measures were stromal cell density (SCD) and the pattern of cell distribution.

RESULTS

Posterior SCD was significantly higher in post-PK eyes compared with controls (387±96 vs 219±30 cell/mm², p<0.0001). A distinct layer densely populated by keratocyte-like cells, corresponding to the last visible row of nuclei before the DM, was observed in post-PK eyes but not in controls. Nuclei of these cells appeared irregularly dispersed or grouped in clusters, and in some cases arranged in columns along a preferred direction.

CONCLUSIONS

A distinct pre-DM layer of keratocyte-like cells is present in post-PK eyes potentially contributing to the previously described natural plane of separation during repeat keratoplasties. Further studies are needed to clarify the origin and clinical implications of this finding.

Ten-year outcomes of repeat keratoplasty for optical indications

Aim

To analyze the clinical outcomes of repeat keratoplasties following a failed primary optical keratoplasty in an Asian population.

Methods

In this prospective cohort study, clinical data of consecutive patients who had repeat keratoplasty at Singapore National Eye Centre from 2007 to 2020 were recorded from our ongoing Singapore Corneal Transplant Registry.

Results

A total of 284 first regrafts (181 Descemet stripping automated endothelial keratoplasty (EK), 63 penetrating keratoplasty (PK), 21 Descemet membrane endothelial keratoplasty, and 19 deep anterior lamellar keratoplasty (DALK)) were analyzed. Graft rejection (38.4%) and late endothelial failure (15.8%) were the main causes of initial graft failure. PK/EK and EK/EK had better one-year postoperative best corrected visual acuity compared to PK/PK (p = 0.006 and p < 0.001 respectively). Kaplan-Meier 10-year cumulative regraft survival probabilities were 69.2% for PK/EK, 52.8% for EK/EK, and 43.1% for PK/PK. Regraft survival was 100% for DALK/PK, DALK/DALK, and DALK/EK at three to 5 years. Log-rank test showed higher survival of PK/EK compared to PK/PK (p = 0.002) and EK/PK (p = 0.009), and of EK/EK compared to PK/PK (p = 0.003) and EK/PK (p = 0.005). High-risk regrafts had significantly lower 10-year survival probabilities compared to non-high-risk regrafts (p = 0.045). Cox multiple regression analysis showed male gender (p = 0.023), PK regraft (p = 0.003), regraft rejection (p = 0.003), and initial graft indications of pseudophakic bullous keratopathy (p = 0.005) and aphakic bullous keratopathy (p = 0.004) to be risk factors for regraft failure, while longer time to regraft was associated with decreased risk of failure (p = 0.013).

Conclusion

Performing EK for failed optical PK or EK significantly improved regraft survival compared to repeat PK. Regrafts performed for failed initial DALK grafts did well regardless of type.

Biomechanical behavior of deep anterior lamellar keratoplasty: a finite element analysis

Deep Anterior Lamellar Keratoplasty (DALK) is a surgical procedure used to restore sight and manage corneal diseases by replacing cloudy corneal tissue with allogeneic normal corneal tissue or artificial corneal material. However, the limited availability and mechanical defects of artificial corneal materials pose challenges in DALK. To predicting postoperative mechanical behavior of Deep Anterior Lamellar Keratoplasty (DALK), a three-dimensional finite element model of the postoperative DALK cornea with suture holes was developed. The postoperative corneal displacement and von Mises (VM) stress changes were also simulated under varying depths of cut (DOC: 0.16-0.26 μm), intraocular pressure (IOP: 12, 15, 18 mmHg), and central corneal thickness (CCT: 420-620 μm). The model indicated that higher IOP and CCT were associated with improved postoperative corneal stability. The postoperative corneal displacement increased from the edge to the center, while the maximum VM stress value occurs at the corneal suture hole. Corneal displacement and VM stress decrease with increasing CCT and decreasing IOP. DOC has a slight effect on corneal displacement and VM stress, with an overall positive relationship. The model has potential application in the preoperative assessment of risk in keratoplasty.

Etiology-Specific Comparison of the Long-Term Clinical Outcome of Repeat Deep Anterior Lamellar Keratoplasty for Optical Indications

PURPOSE

The aim of this study was to evaluate the etiology-specific clinical outcomes and complications of repeat deep anterior lamellar keratoplasty (DALK) after failed DALK.

METHODS

This retrospective case study included 32 eyes of 27 patients who underwent repeat DALK of 450 cases of DALK performed for optical indications between 1997 and 2013. The patients were divided into 4 etiology-specific subgroups (the corneal dystrophy, ocular surface disease, stromal scar, and others) or those with or without limbal stem cell deficiency (LSCD). The clinical outcomes evaluated were graft survival, best-corrected visual acuity, endothelial cell density, and complications.

RESULTS

The mean postoperative follow-up duration was 69.6 ± 54.8 months. The 1-, 3-, and 5-year overall graft survival rate were 76.7%, 57.5%, and 38.8% respectively. The graft survival rate was the highest in the corneal dystrophy group ( P = 0.0014) and was significantly ( P = 0.0010) higher in eyes without LSCD than in eyes with LSCD. There were no significant differences in the graft survival rates between the previous and current DALK groups. The postoperative best-corrected visual acuity of all subjects improved significantly. The postoperative endothelial cell density did not decrease after repeat DALK. There were no significant differences in the incidence of complications between patients with and without LSCD, except the incidence of persistent epithelial defects.

CONCLUSIONS

Repeat DALK had favorable outcomes in all etiology-specific groups, whereas eyes with LSCD required careful assessment of the ocular surface to avoid graft failure due to persistent epithelial defects.

Keratoplasty Registries: Lessons Learned

ABSTRACT

Clinical registries have been developed for decades in the field of ophthalmology, and they are especially well-suited to the study of keratoplasty practices. A comprehensive donor/recipient registry system can provide insight into donor, recipient, and surgical factors associated with immediate and long-term outcomes and adverse reactions. Furthermore, linkage with demographic databases can elucidate relationships with social determinants of health and potentially shape public policy. The vast sample size and multicenter nature of registries enable researchers to conduct sophisticated multivariate or multilayered analyses. In this review, we aim to emphasize the importance of registry data for keratoplasty practice and 1) summarize the structure of current keratoplasty registries; 2) examine the features and scientific contributions of the registries from Australia, the United Kingdom, Singapore, the Netherlands, Sweden, Eye Bank Association of America, and European Cornea and Cell Transplant registries; 3) compare registry-based studies with large single-site clinical studies; 4) compare registry-based studies with randomized control studies; and 5) make recommendations for future development of keratoplasty registries. Keratoplasty registries have increased our knowledge of corneal transplant practices and their outcomes. Future keratoplasty registry-based studies may be further strengthened by record linkage, data sharing, and international collaboration.

Indications and Surgical Techniques for Repeat Corneal Transplantation in Eastern China: A Twelve-Year Study

Purpose

To analyze the indications and surgical procedures for repeat keratoplasty in eastern China from 2008 to 2019.

Methods

This retrospective descriptive study included 418 eyes of 411 patients who underwent no less than 2 keratoplasties at the Eye, Ear, Nose and Throat Hospital of Fudan University from 2008 to 2019. Medical charts were reviewed. The primary indications for repeat keratoplasty, the reasons for regrafting, and the surgical techniques used in the treatment were collected and analyzed.

Results

Among 418 eyes, 337 eyes (80.6%) had one repeat keratoplasty, and 81 eyes (19.4%) had multiple repeat keratoplasties (≥2 repeat keratoplasties). The median interval between the initial keratoplasty and the first repeat keratoplasty was 25 months, and that between two keratoplasties after the first repeat keratoplasty was 27.5 months. Infectious keratitis was the leading primary indication for single repeat keratoplasty (80 cases, 23.7%) and multiple repeat keratoplasties (19 cases, 23.5%). The second most common primary indication was bullous keratopathy for single repeat keratoplasty (49 eyes, 14.5%) and chemical injury for multiple repeat keratoplasties (14 eyes, 17.3%). The main reason for regrafting was allograft rejection (262 cases, 49.3%), followed by endothelial dysfunction (92 cases, 17.3%), and for vision improvement after tectonic keratoplasty (60 cases, 11.3%). Penetrating keratoplasty (PKP) was the major technique used in repeat keratoplasty (447 cases, 84.2%). However, Descemet stripping endothelial keratoplasty was more frequently used than PKP (72.4% vs. 27.6%, P < 0.001) in the treatment of failed endothelial keratoplasty.

Conclusion

Infectious keratitis was still the leading cause of repeat keratoplasty in eastern China. Although PKP remains the major technique of repeat keratoplasty, the application of customized lamellar keratoplasty has greatly expanded in the last decade. Cautious selection of indications, surgical techniques, and timing for surgery is crucial for a good prognosis after repeat keratoplasty.

Pneumatic Dissection for Large-Diameter (9-mm) Deep Anterior Lamellar Keratoplasty in Eyes With Previous Anterior Lamellar Keratoplasty

PURPOSE

To evaluate the surgical and 3-year clinical outcomes of modified big-bubble 9-mm deep anterior lamellar keratoplasty (DALK) in eyes with previous ALK (ALK).

METHODS

In this interventional case series, 21 consecutive eyes with unsatisfactory vision after ALK (superficial ALK n = 9; laser-assisted ALK n = 7; and epikeratophakia n = 5) underwent large-diameter (9-mm) DALK. The surgery involved deep trephination based on the anterior segment optical coherence tomography pachymetry measurement at 9-mm diameter, pneumatic dissection from the base of the trephination and limited stromal clearance of the optical zone (6 mm). Main outcome measures were success rates of pneumatic dissection, best spectacle-corrected visual acuity, and complication rates.

RESULTS

Pneumatic dissection with type 1 bubble formation succeeded in 19 (90%) eyes. In the 2 remaining cases, the 6-mm optical zone was cleared by manual dissection. Perforation occurred in one of the latter cases; no procedure was converted to penetrating keratoplasty. One month after complete suture removal, the preoperative mean best spectacle-corrected visual acuity (0.75 ± 0.23 logMAR) improved to 0.09 ± 0.10 logMAR (P < 0.001) and remained stable up to 3 years after surgery. At the final follow-up, refractive astigmatism was ≤4.5 and <6 D in 20 (95%) and 21 (100%) eyes, respectively. Stromal rejection was observed in 2 eyes (10%) and was treated successfully with steroids.

CONCLUSIONS

Even in eyes with previous ALK, pneumatic dissection can be achieved through a modified DALK technique with a low risk of complications and excellent visual and refractive outcomes.

Corneal transplantation after failed grafts: Options and outcomes

Corneal transplantation is the most commonly performed human tissue transplantation procedure worldwide. Because of the large number of transplants, corneal graft failure has become one of the most common indications for corneal transplantation. The relatively recently developed lamellar transplant techniques have brought about specific potential complications leading to graft failure that may require different approaches to repeat transplantation other than penetrating keratoplasty. On the other hand, these new lamellar techniques also provide novel ways of rescuing failed penetrating grafts, with potential advantages over successive penetrating keratoplasties, such as reduced intraoperative risks and faster visual rehabilitation. We summarize the incidence and risk factors of graft failure for penetrating and lamellar (stromal and endothelial) corneal transplants and discuss the various surgical alternatives currently available to rescue such failed grafts, with a focus on the reported outcomes and limitations.

Deep Anterior Lamellar Keratoplasty After Previous Anterior Lamellar Keratoplasty to Improve the Visual Outcomes

PURPOSE

To describe a series of patients who underwent deep anterior lamellar keratoplasty (DALK) after previous anterior lamellar keratoplasty (ALK) to improve their visual outcomes.

METHODS

This is a retrospective case series of 9 DALK eyes (9 patients) with a history of previous ALK and an unsatisfactory visual outcome. Surgery was performed in all cases at least 3 years after ALK. Cannula big bubble, air viscobubble, and manual dissection techniques were performed. Preoperative and postoperative best-corrected visual acuity, residual recipient bed thickness, and endothelial cell count were evaluated. Follow-up was at least 24 months for all eyes.

RESULTS

Two subtotal anterior lamellar keratoplasties (through 1 type 1 big bubble and 1 air viscobubble) and 7 manual dissection DALKs were achieved. A small rupture of the residual recipient bed occurred during 1 case, and it was managed without penetrating keratoplasty conversion. Mean best-corrected visual acuity improved from 0.64 to 0.09 logMAR. Postoperative residual recipient central bed thickness was less than 80 μm in all cases. No postoperative complications were recorded at the last follow-up (24-36 months postoperatively).

CONCLUSIONS

Different DALK techniques can be successfully used to improve visual acuity in previous ALK eyes with an unsatisfactory visual outcome.