Post-Keratoplasty Microbial Keratitis in the Era of Lamellar Transplants-A Comprehensive Review

Microbial keratitis in a post-transplant cornea should be considered a distinct entity from microbial keratitis in a non-transplant cornea. Firstly, the use of immunosuppressive treatments and sutures in corneal transplants changes the etiology of keratitis. Secondly, corneal transplant has an impact on corneal biomechanics and structure, which facilitates the spread of infection. Finally, the emergence of lamellar transplants has introduced a new form of keratitis known as interface keratitis. Given these factors, there is a clear need to update our understanding of and management strategies for microbial keratitis following corneal transplantation, especially in the era of lamellar transplants. To address this, a comprehensive review is provided, covering the incidence, risk factors, causes, and timing of microbial keratitis, as well as both clinical and surgical management approaches for its treatment in cases of penetrating and lamellar corneal transplants.

Congenital stromal corneal dystrophy in a Spanish family: Clinical, genetic and histological analysis

PURPOSE

To present the clinical, genetic, and histopathological features of the ninth family affected by congenital stromal corneal dystrophy (CSCD) to date.

METHODS

Twelve cases of a Spanish family affected by CSCD were analyzed regarding history, visual acuity (VA, decimal scale), an ophthalmologic exam and specular microscopy. Five eyes were treated by deep anterior lamellar keratoplasty (DALK), and thirteen eyes by penetrating keratoplasty (PK). In the two last generations, a genetic study was performed.

RESULTS

Most of the patients affected were born with opaque corneas except for three, whose corneas were clear at birth. Biomicroscopy showed a whitish diffuse stromal opacity with an unaltered epithelium, causing poor VA (from hand motions to 0.4). Patients treated with PK presented mean postoperative VA of 0.19±0.20 over a follow-up time of 235.3±101.4months with 38% recurrences. Patients who underwent DALK experienced VA improvement to 0.17±0.11 over a follow-up time of 10.8±2.6months without signs of recurrence. In the latter, the big bubble technique was not achieved, so a manual technique was performed. The genetic study showed heterozygosis for a 1-bp deletion at nucleotide 962 in exon 8 of the decorin gene.

CONCLUSIONS

CSCD is a rare entity, which should be treated by DALK whenever possible, obtaining better results than PK. Close monitoring of children of affected individuals is important, because CSCD can progress during the early years of life.

Familial primary calcific band-shaped keratopathy with late onset systemic disease: a case series and review of the literature

BACKGROUND

Familial calcific band-shaped keratopathy (BSK) is a very rare disease, with no underlying cause. There is no underlying disease in this form of the disease. This article introduces a family with seven children, three of whom were diagnosed with familial primary calcific BSK. One of them developed a systemic disease 38 years after ocular manifestation.

CASE PRESENTATION

In this case report, three Iranian siblings from a family with familial calcific band-shaped keratopathy (BSK) are introduced. Systemic and ocular examinations performed on these patients indicated the occurrence of chronic kidney disease in the older child, a 41-year-old woman, 38 years after ocular manifestation. The examinations conducted on the other two siblings revealed no pathological findings. The 41-year-old sister and 37-year-old brother underwent unilateral deep anterior lamellar keratoplasty (DALK), while the 33-year-old sister underwent bilateral superficial keratectomy (SK).

CONCLUSION

Considering the late onset of systemic disease in one of the siblings diagnosed with familial calcific band-shaped keratopathy (BSK), it is crucial to emphasize the necessity of long-term follow-up for these patients and their families.

Endothelial Migration and Regeneration after Penetrating Trauma Injury in a Deep Anterior Lamellar Keratoplasty Graft: Case Presentation and Literature Overview

Background: Traumatic injuries in eyes previously treated with Deep Anterior Lamellar Keratoplasty (DALK) can lead to ruptures in the Descemet Membrane (DM) and damage to the corneal endothelium, a crucial layer for maintaining corneal clarity. Due to cell cycle constraints, the human corneal endothelium cannot proliferate; instead, it compensates for injury through cell enlargement and migration from adjacent areas. Methods: This study examines a notable case of corneal endothelial cell migration following a penetrating eye injury in a patient previously treated with DALK for keratoconus, supplemented by a review of relevant literature to contextualize the regenerative response. Results: A 39-year-old male with a history of DALK suffered a traumatic eye injury, resulting in damage to the Descemet Membrane and loss of the crystalline lens. After primary repair and considerations for further surgery, the patient's cornea cleared remarkably, with an improved visual acuity. This demonstrates the DM's potential for self-repair through endothelial cell migration. Conclusions: The outcomes suggest that delaying corneal transplant surgery for up to 3 months following Descemet Membrane injury due to ocular trauma could be advantageous. Allowing time for natural healing processes might eliminate the need for further invasive surgeries, thereby improving patient recovery outcomes.

Bovine pericardium membrane (TutoPatch) for emergency repair of total corneal melting over an infected corneal graft

Purpose

Corneal perforation due to severe melting is a very dangerous, sight-threatening condition requiring immediate management due to the high risk of endophthalmitis and critical hypotony. In the case of perforated corneal grafts, retransplantation is usually postponed to avoid the detrimental effects of inflammation on the new graft. We describe the first case of the use of a TutoPatch graft for emergency replacement of a lamellar graft perforation over acute infectious total melting.

Observations

A 42-year-old male patient presented to the Emergency Department with pain in the left eye, which was red photophobic. He had been treated with bilateral deep anterior lamellar keratoplasty (DALK) for advanced keratoconus 5 years previously and had been experiencing recurrent corneal ulcers in the left eye within the last 8 months. Clinical examination documented corneal perforation over acute infectious melting involving the total graft surface in the left eye. The infected graft was removed along with the perforated infected residual Descemet membrane, and a double-layer TutoPatch covering was sutured to the host's margin with 10.0 nylon. The covering was left in place for three weeks, allowing the patient to undergo retransplant three weeks later without complications.

Conclusions and importance

TutoPatch covering can be safely used as an easy-to-preserve emergency material for a temporary bridge to retransplantation in large acute infectious corneal melting.

Indications and types of keratoplasties: Trends in the past 10 years (2011-2020) in Eastern India

Purpose

To observe the trends of various types of keratoplasties in different etiologies over a period of 10 years (2011-2020) in a tertiary eye care center of eastern India.

Methods

A retrospective review of patients undergoing keratoplasties from 2011 to 2020 was performed in a tertiary eye care hospital situated in eastern part of India. Apart from demographic data, primary indication for each surgery and type of procedure carried out was recorded. For comparison, data were divided into two time periods: Group I: Jan 2011 to Dec 2015 and Group II: Jan 2016 to Dec 2020.

Results

Over a period of 10 years, a total of 2365 (Group I: 902, Group II: 1463) keratoplasties were performed. The average age of patients was 45.8 ± 19.9 and 46.9 ± 20.9 years in Group I and Group II, respectively. Among all the corneal grafts, 1747 (74%) surgeries were full-thickness. Although optical penetrating keratoplasty (OPK) was most the common indication for full-thickness keratoplasties, Descemet's stripping endothelial keratoplasty (DSEK) remained most performed lamellar keratoplasty. Keratitis, corneal scars, and bullous keratopathies remain to be most common indications in both groups. Number of lamellar keratoplasties increased significantly from Group I to Group II for corneal scars (P = 0.02), bullous keratopathies (P = 0.01), and endothelial dystrophies (P = 0.00).

Conclusion

With change in time, the indication and technique of keratoplasty has witnessed a changing trend from full-thickness keratoplasty to lamellar keratoplasty. There is rise in trend of lamellar keratoplasties over the period.

Secondary angle closure glaucoma due to iatrogenic big bubble formation in manual DALK for stromal degeneration: An unusual presentation

A 65-year-old male was planned for Deep anterior lamellar keratoplasty (DALK) to improve his visual quality from the underlying spheroidal degeneration along the visual axis. An attempt for a big bubble was futile, hence converted to a manual DALK. On postoperative day 1, he developed secondary angle closure glaucoma due to reverse pupillary block by the host DM. Decompression of the big bubble was done and angle closure was resolved with a good visual outcome at 1-month post-op. We present the first case of secondary angle closure glaucoma due to reverse pupillary block by a big bubble in a rigid cornea. Abbreviations: DALK = Deep anterior lamellar keratoplasty, OD = oculus dexter, OS = oculus sinister, DS = Diopters Sphere, DC = Diopters cylinder, AS-OCT = anterior segment optical coherence tomography, DM = Descemet's membrane, IOP - Intraocular pressure, GHJ = Graft-host junction, BSS = Balanced salt solution.

Comparison of Robot-Assisted and Manual Cannula Insertion in Simulated Big-Bubble Deep Anterior Lamellar Keratoplasty

This study aimed to compare the efficacy of robot-assisted and manual cannula insertion in simulated big-bubble deep anterior lamellar keratoplasty (DALK). Novice surgeons with no prior experience in performing DALK were trained to perform the procedure using manual or robot-assisted techniques. The results showed that both methods could generate an airtight tunnel in the porcine cornea, and result in successful generation of a deep stromal demarcation plane representing sufficient depth reached for big-bubble generation in most cases. However, the combination of intraoperative OCT and robotic assistance received a significant increase in the depth of achieved detachment in non-perforated cases, comprising a mean of 89% as opposed to 85% of the cornea in manual trials. This research suggests that robot-assisted DALK may offer certain advantages over manual techniques, particularly when used in conjunction with intraoperative OCT.

Intraoperative OCT for Lamellar Corneal Surgery: A User Guide

Intraoperative OCT is an innovative and promising technology which allows anterior and posterior segment ocular surgeons to obtain a near-histologic cross-sectional and tomographic image of the tissues. Intraoperative OCT has several applications in ocular surgery which are particularly interesting in the context of corneal transplantation. Indeed, iOCT images provide a direct and meticulous visualization of the anatomy, which could guide surgical decisions. In particular, during both big-bubble and manual DALK, the visualization of the relationship between the corneal layers and instruments allows the surgeon to obtain a more desirable depth of the trephination, thus achieving more type 1 bubbles, better regularity of the plane, and a reduced risk of DM perforation. During EK procedures, iOCT supplies information about proper descemetorhexis, graft orientation, and interface quality in order to optimize the postoperative adhesion and reduce the need for re-bubbling. Finally, mushroom PK, a challenging technique for many surgeons, can be aided through the use of iOCT since it guides the correct apposition of the lamellae and their centration. The technology of iOCT is still evolving: a larger field of view could allow for the visualization of all surgical fields, and automated tracking and iOCT autofocusing guarantee the continued centration of the image.

Outcomes of refractive implantable lens implantation after deep anterior lamellar keratoplasty

Purpose

To assess the refractive outcomes and effect on endothelial cell density of refractive implantable lens (RIL) implantation following deep anterior lamellar keratoplasty (DALK).

Methods

A retrospective study was conducted on 10 eyes of 10 patients who had undergone DALK and subsequently underwent toric RIL implantation. The patients were followed up over a period of 1 year. The parameters compared were uncorrected and best corrected visual acuity, spherical and cylindrical acceptance, mean refractive spherical equivalent, and endothelial cell counts.

Results

There was a significant improvement (P < 0.05) from preoperatively to 1 month postoperatively in the mean log of minimum angle of resolution (logMAR) uncorrected distance visual acuity (UCVA; 1.1 ± 0.1 to 0.3 ± 0.1), spherical refraction (5.4 ± 3.8 to 0.3 ± 0.1 D), cylindrical refraction (5.4 ± 3.2 to 0.8 ± 0.7 D), and MRSE (7.4 ± 3.5 to 0.5 ± 0.4 D). Three patients achieved spectacle independence for distance vision with a residual MRSE less than 1 D in the other cases. A stable refraction was maintained up to 1 year follow-up in all cases. There was a 2.3% mean decline in endothelial cell counts at 1 year of follow-up. No intraoperative or postoperative complications were seen in any case up to 1 year of follow-up.

Conclusion

RIL implantation is an effective and safe procedure for the correction of high ametropia post-DALK.

Microbiological Testing of Split-Cornea Transplantation

PURPOSE

By splitting a donor cornea into an anterior and a posterior donor lamella, the need for donor tissue can be reduced in times of lack of donors. Current eye bank regulations limit the use of each donor cornea to one recipient.

METHODS

The anterior lamella not applied to the patient after each sterile DMEK preparation performed was stored for one week and was microbiologically controlled on day 7.

RESULTS

Between October 2020 and December 2021, microbiological controls of 108 consecutive anterior lamellae were performed at the Department of Ophthalmology, University of Duesseldorf, without any contamination found.

CONCLUSION

Our data suggest split-cornea transplantation is a microbiologically safe procedure.

Rediscovering a valuable manual Deep Anterior Lamellar Keratoplasty (DALK) technique: Outcomes of 42 "Peeling-off" DALK

PURPOSE

Residual bed thickness in DALK should be less than 80μm to provide optimal visual outcomes. "Peeling-off" is a manual DALK technique, which separates the anterior stroma by pulling the deep stromal lamellae following the plane of their lowest adhesion, which is usually very deep. The purpose of this study is to measure the residual bed thickness achievable with this technique.

METHODS

Retrospective case series of "Peeling-off" DALK cases performed between January 2014 and January 2021 with at least 1 year of follow-up. Indications for DALK, intraoperative and postoperative complications, residual recipient bed thickness at 1 day and at 1 month after surgery, and postoperative best corrected visual acuity (BCVA) at 1 year of follow up were evaluated.

RESULTS

42 eyes (42 patients) underwent DALK performed with "Peeling-off" technique. Indications for surgery were keratoconus in 33 eyes and stromal scar in 9 eyes. "Peeling-off" technique was used as a rescue approach to perform a DALK after a failed Big-Bubble in all cases, and also failed Air-Visco-Bubble in some cases. No intraoperative and postoperative complications were recorded. Residual recipient bed thickness was deep and regular, measuring 42 microns at 1 day postoperative (range 21-65 microns) and 23 microns (range 17-26 microns) at 1 month postoperative. Mean postoperative BCVA at 1 year of follow up was 0.18 logMAR ± 0.09.

CONCLUSION

"Peeling-off" DALK is a valuable manual technique that achieves a deep stromal plane with optimal visual outcomes.

Corneal aberrations, densitometry on scheimpflug imaging, and visual acuity after deep anterior lamellar keratoplasty

PURPOSE

To evaluate visual acuity, corneal aberrations, and densitometry post deep anterior lamellar keratoplasty (DALK).

METHODS

Twenty-five eyes of 25 patients who underwent DALK for corneal stromal diseases with normal endothelium were enrolled in a prospective interventional study. Evaluation for corneal aberrations and densitometry postoperatively was performed using Scheimpflug imaging at 6 months. Anterior Segment Optical Coherence Tomography (ASOCT) was done for host-graft morphology. Correlation analysis of postoperative best-corrected visual acuity with corneal aberrations and corneal densitometry (CD) was performed.

RESULTS

Big bubble deep anterior lamellar keratoplasty (BB-DALK) was successful in 18 patients, while 7 eyes underwent manual dissection due to failed BB (Big Bubble) technique. The mean BSCVA was 1.35 ± 0.46 logMAR units pre-operatively which improved to 0.36 ± 0.19 logMAR units post DALK at 6 months (P < 0.001). The mean Root Mean Square (RMS) (μm) of the magnitude of total corneal aberrations, HOA and LOA from central 6mm zone of cornea were 14.6 ± 9.2, 4.7 ± 2.9, and 13.8 ± 8.8, respectively. The mean anterior (120μm), central and posterior corneal (60μm) densitometry in 0-2mm zone were 25.8 ± 7.7 GSU, 18.7 ± 4.16 GSU and 10.09 ± 3.9 GSU respectively. A statistically significant correlation of postoperative residual stromal bed thickness, total corneal HOA, LOA, total corneal aberrations, HOA front and posterior corneal densitometry (0-2mm zone) with postoperative BSCVA was found.

CONCLUSION

Though there is a significant improvement in BSCVA after DALK, the quality of vision in terms of aberrometry and densitometry is suboptimal, especially in cases undergoing manual DALK compared to those undergoing big bubble formation.

Femto-LASIK after Deep Anterior Lamellar Keratoplasty to Correct Residual Astigmatism: A Long-Term Case Series Study

Purpose: To evaluate the long-term outcomes of femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) to correct residual astigmatism after deep anterior lamellar keratoplasty (DALK). Methods: This retrospective case series study included 10 eyes that underwent Femto-LASIK after a DALK. The refractive error, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, thinnest corneal thickness (TCT), and central corneal thickness (CCT) were registered. The postoperative follow-up ranged between 36 and 60 months. Results: All surgeries were uneventful, with no intra- or postoperative complications. The mean UDVA (Snellen scale) rose from 0.13 ± 0.05 to 0.47 ± 0.15 six months after Femto-LASIK (p < 0.001). All cases experienced a significant improvement in UDVA. None of the eyes lost lines of CDVA, and seven eyes (70%) improved the CDVA compared to preoperative values. The refractive cylinder changed from a preoperative value of −3.88 ± 1.00 D to −0.93 ± 0.39 six months after Femto-LASIK (p < 0.0001). In eight eyes (80%), the UDVA and refractive outcomes remained stable at postoperative follow-up visits. In contrast, one eye experienced a refractive regression over the follow-up. TCT and CCT were stable at the different postoperative follow-up visits. Conclusions: Our findings suggest that Femto-LASIK might safely and effectively corrects residual astigmatism after DALK. Despite these encouraging results, further long-term studies, including a larger number of cases, are required to confirm the safety of the procedure. The refractive stability in eyes with prior RK might be lower than for other DALK indications.

Update on Pediatric Corneal Diseases and Keratoplasty

Managing pediatric corneal disorders is challenging as the prognosis of pediatric keratoplasty depends on several factors. Advancements in the genetic basis of congenital corneal diseases and investigations in congenital corneal conditions provide a better understanding of pediatric corneal conditions. Surgeons performing keratoplasty in children now have a choice of various techniques. Evolving surgical techniques of anterior lamellar and endothelial keratoplasties has expanded the management interventions in these pediatric corneal morbidity conditions; however, considerable concerns still exist in association with corneal transplantation in infants and children. Outcomes in pediatric keratoplasty depend upon the preoperative indications, the timing of surgical intervention, intraoperative and postoperative factors including the patient/care givers' compliance. Factors such as low scleral rigidity, higher rate of graft failure, need for frequent examinations under anesthesia, and difficulty in optimal visual acuity assessment still remain a considerable challenge in pediatric scenarios. In children, deprivation amblyopia as a result of the corneal opacification can adversely affect visual development, causing dense amblyopia. Outcomes to surgical interventions for management of corneal opacification in children is further compromised by the pre-existing amblyopia apart from the concerns of refractive outcome of the graft. Graft rejection, graft infection, amblyopia, and glaucoma continue to be serious concerns. In recent years both anterior and posterior lamellar keratoplasty techniques are being increasingly performed in pediatric eyes, which offer advantages in the form of lower risk of graft rejection. The timing of surgery, careful case selection, cautious intraoperative approach, and optimal postoperative management can improve the anatomical and functional outcome in difficult cases.

Deep anterior lamellar keratoplasty for keratoconus: Elements for success

Advanced keratoconus may require keratoplasty when the patient can no longer achieve functional vision with glasses and contact lenses. Deep anterior lamellar keratoplasty (DALK) has become the surgical treatment of choice due to its undisputed advantages over penetrating keratoplasty including the reduced risk of intraoperative complications, the absence of endothelial immune rejection, and the longer graft survival. Albeit "big-bubble" DALK still represents the most popular surgical method, several modifications have been developed over the years. This allowed standardization of the technique, with improved success rates and clinical outcomes. This review presents an overview on the literature on DALK surgery for keratoconus. We discuss state-of-the art surgical techniques, current evidence on the clinical outcomes and complications as well as possible future directions.

Update on Suture Techniques in Corneal Transplantation: A Systematic Review

Effective suturing remains key to achieving successful outcomes in corneal surgery, especially anterior lamellar keratoplasty and full thickness transplantation. Limitations in the technique may result in complications such as wound leak, infection, or high astigmatism post corneal graft. By using a systematic approach, this study reviews articles and conducts content analysis based on update 2020 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria). The aim of this paper is to summarize the state of the art of corneal suturing techniques for every type of corneal transplant and patient age and also their outcomes regarding astigmatism and complications. Future developments for corneal transplantation will be also discussed. This is important because especially the young surgeon must have knowledge of the implications of every suture performed in order to achieve consistent and predictable post-operative outcomes and also be aware of all the possible complications.

Downward viewing common-path optical coherence tomography guided hydro-dissection needle for DALK

Deep anterior lamellar keratoplasty (DALK) is a partial-thickness cornea transplant procedure in which only the recipient's stroma is replaced, leaving the host's Descemet's membrane (DM) and endothelium intact. This highly challenging "Big Bubble" procedure requires micron accuracy to insert a hydro-dissection needle as close as possible to the DM. Here, we report the design and evaluation of a downward viewing common-path optical coherence tomography (OCT) guided hydro-dissection needle for DALK. This design offers the flexibility of using different insertion angles and needle sizes. With the fiber situated outside the needle and eye, the needle can use its' full lumen for a smoother air/fluid injection and image quality is improved. The common-path OCT probe uses a bare optical fiber with its tip cleaved at the right angle for both reference and sample arm which is encapsulated in a 25-gauge stainless still tube. The fiber was set up vertically with a half-ball epoxy lens at the end to provide an A-scan with an 11-degree downward field of view. The hydro dissection needle was set up at 70 degrees from vertical and the relative position between the fiber end and the needle tip remained constant during the insertion. The fiber and needle were aligned by a customized needle driver to allow the needle tip and tissue underneath to both be imaged within the same A-scan. Fresh porcine eyes (N = 5) were used for the studies. The needle tip position, the stroma, and DM were successfully identified from the A-scan during the whole insertion process. The results showed the downward viewing OCT distal sensor can accurately guide the needle insertion for DALK and improved the average insertion depth compared to freehand insertion.

Ultrastructural Alterations of Grafted Corneal Buttons: The Anatomic Basis for Stromal Peeling Along a Natural Plane of Separation

PURPOSE

To examine the ultrastructure of the natural plane of separation in grafted corneas and evaluate the outcomes of stromal peeling.

DESIGN

Interventional case series.

METHODS

In this multicenter study, stromal peeling was attempted in 96 consecutive eyes with unsatisfactory vision following penetrating keratoplasty (PK) for keratoconus (n = 79), herpetic keratitis (n = 11), and granular dystrophy (n = 6). Stromal exchange was performed by (1) 9 mm partial-thickness trephination; (2) creation of a corneal flap across the PK wound; (3) opening of the stromal component of the PK wound until a smooth, translucent natural plane was identified; (4) severing the attachment of the PK scar; (5) stromal peeling along the identified plane; and (6) suturing of donor lamella. Grafted corneas from cases that mandated conversion to PK were processed for transmission electron microscopy.

RESULTS

The natural plane of separation was identified in all cases. Stromal exchange was successfully completed in 84 cases (87.5%). Snellen visual acuity ≥20/40 and ≥20/25 was reached in 93% and 72% of cases at 3 years (n = 49) and 86% and 62% at 4 years (n = 21) postoperatively. Mean endothelial cell loss at 1 year was 6.6% ± 9.5%. Stromal peeling occurred along a plane lined with a continuous layer of keratocytes separating pre-Descemet membrane (DM) stroma, DM, and endothelium from the anterior stroma. Pre-DM stroma was made of poorly organized lamellae containing widely spaced, randomly arranged collagen fibrils.

CONCLUSIONS

Ultrastructural alterations in the stromal microarchitecture of grafted corneas provide evidence of a natural plane of separation identified intraoperatively. Stromal peeling can be successfully performed in post-PK eyes with various stromal pathology.

Tectonic Deep Anterior Lamellar Keratoplasty to Treat Corneal Perforation and Descemetocele from Microbial Keratitis

Purpose

To evaluate the result of tectonic deep anterior lamellar keratoplasty (DALK) for keratitis with perforation and descemetocele.

Patients and Methods

A prospective clinical study of 36 patients (36 eyes) treated with tectonic DALK for corneal perforation or descemetocele from microbial keratitis managed at the Vietnam National Eye Hospital over a two-year period. The surgical technique was manual lamellar dissection. The grafts were harvested from the anterior corneal cap of pre-cut donor tissues used for DSAEK or donor corneas with a low endothelial cell count.

Results

A mean age was 55.36 ± 13.98 years (ranged from 25 to 75 years). Female gender represented 52%. causative agents were herpes simplex virus (58.3%), bacteria (22.2%), fungi (13.9%) and microsporidia (5.6%). There were 24 eyes with descemetocele (66.7%) and 12 with perforation (33.3%). There were 33 successful cases (91.7%) and 3 failed cases (8.3%). Best corrected visual acuity (BCVA) improved in 28 eyes (84.8%). The range of post-operative BCVA was from hand motions to 20/70. Eleven eyes (33.3%) attained vision 20/200 and higher. Clear graft was obtained in 15 eyes (45.5%), while mild or severe graft opacity was observed in 14 eyes (42.4%), and 4 eyes (12.1%), respectively. Surgical complications included descemet rupture (20.8%), pseudo anterior chamber (41.6%), persistent corneal epithelial defects (8.3%), reinfection (11.1%), glaucoma or ocular hypertension (5.6%) and cataract (8.3%).

Conclusion

The study demonstrates that DALK is an effective procedure to treat corneal descemetocele, especially when an urgent penetrating keratoplasty (PKP) cannot be performed.

Causes of corneal transplant failure: a multicentric study

PURPOSE

To identify the causes of failure of the different surgical corneal graft techniques: penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

This multicentric retrospective study enrolled a consecutive cohort of patients who had undergone any type of keratoplasty between 2001 and 2016. The clinical data were obtained from the patient's medical records, following ethical guidelines, permissions and data protection. The main outcome measured in the study was the cause of graft failure, defined as any irreversible loss of graft transparency capable of compromising vision. The main causes of graft failure were classified as follows: (A) primary graft failure (PGF), (B) immunological rejection, (C) non-rejection (which includes endothelial decompensation without rejection, IOP elevation/glaucoma, diseases of the ocular surface, recurrence of the primary disease, wound dehiscence/hypotonia and trauma, among others) and (D) specific causes of lamellar keratoplasty failure. A descriptive study of the obtained data was carried out. The distribution of the causes of failure was evaluated according to the type of corneal transplant.

RESULTS

Our research included a cohort of 571 keratoplasty failures, of which 509 met the inclusion criteria. The analysis of the causes of the PK failure showed that immunological allograft rejection represented the main cause, with 28.2% of the failures, followed by surface diseases (17.8%) and endothelial decompensation without rejection (17.3%). For the PK re-grafts group, the main cause of failure was immunological allograft rejection (34.0%), followed by diseases of the ocular surface (18.5%). For the DALK group, the failures mainly occurred due to surface diseases such as limbal stem cell insufficiency, infectious keratitis, keratolysis or persistent epithelial defect (37.8%). However, the main reason for failure in the DSAEK group was endothelial decompensation without rejection (31.9%) while primary graft failure was the main cause of failure in the DMEK group (64.1%).

CONCLUSION

The main reason for failure in PK was immunological allograft rejection, both in primary and secondary transplants. The leading causes for failure were diseases of the ocular surface in the DALK population, endothelial decompensation without rejection in DSAEK and primary graft failure in DMEK.

Primary surgical options for acute corneal hydrops: A review

Acute corneal hydrops usually resolves alone or with medical therapy along the first 4-6 weeks. However, depending on the severity of the corneal edema or the size of the Descemet break, self-healing might be difficult. Years ago, those patients had no more options than corneal transplantation, but surgical alternatives are on the rise in this century. These surgeries are becoming more popular with a variety of techniques relegating penetrating keratoplasty to a residual role. These techniques aim to accelerate corneal healing, reduce the edema, improve visual acuity and prevent from severe complications that may appear if corneal hydrops is not treated rapidly. Feasibility and safety are the favorable aspects of these techniques since the complications rates described remain low. In this review, we emphasize the recently published studies that describe both the techniques and their results.

Preferred practice pattern and observed outcome of deep anterior lamellar keratoplasty - A survey of Indian corneal surgeons

Purpose

This study aimed to assess the preferred surgical technique and outcome of deep anterior lamellar keratoplasty (DALK) among corneal surgeons in India.

Methods

An online questionnaire-based cross-sectional survey was conducted among members of the Cornea Society of India (CSI) with experience of performing >10 DALK procedure. The responses pertaining to their surgical experience, preferred technique, complications, and outcome of DALK were collected and analyzed.

Results

A total of 156 responses were received. In total, 35.9% of participants reported annual keratoplasty of >50, and DALK constituted >25% surgeries for 25% of participants. Ectatic corneal disorder was reported as the most common indication for DALK by 71.6% of the respondents. Big-bubble (BB) DALK (WA-1.82) was the most preferred technique, along with suction trephine (50%) for partial trephination and bottom port cannula (45.5%) for BB formation. On statistical analysis, no difference was observed in the surgeon reported success rate of BB formation with or without anterior lamellar keratectomy (ALK) (χ2 (1,156) = 3.1498, P = 0.08) or paracentesis (χ2 (1,156) = 0.2737, P = 0.60) before stromal air injection, and method of stromal air injection (χ2 (1,156) = 4.7325, P = 0.09). Conversion to penetrating keratoplasty was reported by 16% of participants in >25% cases, while 66.7% reported in <10% cases. Cataract and double anterior chamber were the most common complications. 50% of participants suggested that >20 procedures are required to overcome the learning curve.

Conclusion

BB DALK is the most commonly practiced DALK technique, and its success is independent of ALK and paracentesis being performed prior to air injection and method of air injection (cannula/needle).

Deep anterior lamellar keratoplasty for corneal penetrating wounds

PURPOSE

To report our surgical experience of deep anterior lamellar keratoplasty (DALK) performed in eyes with scarring resulting from a corneal penetrating wound without tissue loss.

METHODS

Case series of three eyes of three patients that underwent DALK for poor vision due to a scar resulting from a previous corneal penetrating wound. Surgery was performed at least 1 year after the initial injury. Manual dissection technique was used in all cases. Preoperative and postoperative best correct visual acuity (BCVA), postoperative residual bed thickness, and postoperative endothelial cell count (ECC) were evaluated.

RESULTS

Preoperative BCVA ranged from 1.3 to 1.0 LogMAR. Two eyes were pseudophakic and one eye had a traumatic cataract. Manual DALK was successfully accomplished in all three cases. The mean residual recipient bed thickness was 103 µm (range 68-130 µm). The mean endothelial cell loss at the 6th month of follow-up was 6% (range 3%-11%) with a further 1% decrease at 4 years. One of the patients underwent cataract surgery and limbal relaxing incisions 1 year after DALK having a total endothelial cell loss of 4.8% at 2 years of follow-up. BCVA at 2 years of follow-up was 0.1 LogMAR (range 0.22-0.0 LogMAR). No episode of rejection was recorded, and all grafts remained clear at last follow-up (5 years, range 4-6 years).

CONCLUSIONS

Manual DALK should be considered in cases of corneal scars in optical zone resulting from penetrating wound.

[Excimer laser-assisted DALK: a case report from the Homburg Keratoconus Center (HKC)]

Indikationen

Ziel der Excimerlaser-gestützten DALK (Excimer-DALK) ist, wie bei der mechanischen DALK, die Behandlung von Keratektasien (Keratokonus und pellucide marginale Degeneration), stromalen Narben oder stromalen Hornhautdystrophien. Voraussetzung für die Operation ist die Abwesenheit von (prä)descemetalen Narben sowie ein gesundes Endothel.

Operationstechnik

Nach der Excimerlaser-gestützten Trepanation auf 80 % der kornealen Dicke an der Trepanationsstelle, einer intrastromalen Lufteingabe (sog. „Big-Bubble“) sowie einer lamellären Hornhautpräparation erfolgt eine lamelläre anteriore Transplantation des endothelfreien Spendergewebes. Diese Technik kombiniert die Vorteile einer DALK und einer Excimerlaser-Trepanation. Wir beschreiben die Schritte einer Excimer-DALK aus unserem Homburger Keratokonus Center (HKC).

Schlussfolgerungen

Die Excimer-DALK stellt bei Patienten mit gutem Endothel eine gute Behandlungsmöglichkeit dar. Bei einer intraoperativen Perforation bleibt die Möglichkeit einer sog. Konversion zur Excimer-PKP mit allen Vorteilen der Excimerlaser-Trepanation.

Video online

Die Online-Version dieses Beitrags (10.1007/s00347-021-01342-3) enthält ein Video.

Pediatric keratoconus - Current perspectives and clinical challenges

Keratoconus is an ectatic corneal disease characterized by progressive stromal thinning, irregular astigmatism, and defective vision. It can be unilateral or bilateral with asymmetric presentation. It starts at puberty and either progresses rapidly to an advanced stage of the disease or stops in case of delayed onset and slow progression. Pediatric keratoconus is more aggressive than in adults and the management protocols differ because of various rationales such as accelerated progression, advanced stage of disease at the time of diagnosis and co-morbidities. It poses a burden to the society as it affects the quality of life, social, and educational development in children. Hence early diagnosis, recognition of progression, and timely intervention with collagen crosslinking is imperative to arrest the worsening. Association with systemic syndromes and ocular comorbidities can be of concern in pediatric keratoconus. Severe ocular allergy when associated hastens progress and complicates timely intervention of crosslinking treatment and compliance to contact lens wear. Keratoplasty in pediatric keratoconus has good outcomes but can encounter frequent suture-related concerns. This article discusses the epidemiology, etiopathogenesis, clinical challenges, and current perspectives of management of pediatric keratoconus.

Laser-assisted corneal transplantation surgery

Corneal transplant surgeries have a broad range of indications with outcomes largely dependent on surgeon experience. Traditional manual techniques have certain limitations pertaining to the preparation of donor tissue and the recipient bed that might affect the predictability of visual outcomes. Use of lasers for keratoplasty procedures not only improves the repeatability and consistency of the technique, but also enables the surgeon to control the thickness and shape of the transplant tissue tailored to the specific condition. Despite the advantages, cost-effectiveness and technical know-how remain the major challenges. We discuss the various techniques of laser-assisted keratoplasties with respect to their methods, precision, and efficacy in various corneal indications.

Dynamics of Big Bubble Formation During Deep Anterior Lamellar Keratoplasty in Eyes with Advanced Keratoconus

Purpose

To study the dynamics of big bubble (BB) formation in eyes with advanced keratoconus (KC) during deep anterior lamellar keratoplasty (DALK).

Methods

A retrospective review of medical records and videos of DALK surgeries performed during the period from January 2013 to December 2019 on keratoconic eyes. Eyes with formed BB, in the presence of a relatively clear stroma, were included. We studied the following parameters the location of BB commencement, duration from the start of the bubble until complete formation, and the pattern of air passage during the formation process.

Results

A total of 37 eyes met the inclusion criteria. Type 1 BB was formed in 22 eyes with a mean formation time of 1.9 ± 1.1 seconds and a mean bubble diameter of 7.6 ± 1.1 mm. Type 1 BB started in the center as a small dome expanding centrifugally with preceding localized stromal whitening in 19 eyes and without whitening in three eyes. Type 2 BB was formed in 14 eyes with a mean formation time of 0.3 ± 0.12 seconds and a mean bubble diameter of 7.4 ± 1.8 mm. Type 2 BB started in the center in 13 eyes and the mid periphery in one eye, through either direct access to the plane between Descemet’s membrane and the pre-Descemet’s layer in six eyes, or preceded by a small intrastromal bubble in eight eyes. Mixed bubble was observed in one eye, which started as a small central Type 1 BB followed by the rapid formation of a Type 2 BB.

Conclusion

Eyes with KC are associated with central commencements of both Type 1 and Type 2 BB during DALK. Duration of BB formation was significantly faster in Type 2 BB, with most starting as a small intrastromal bubble before air gain access to the plane between DM and stroma.

Real-time segmentation and tracking of excised corneal contour by deep neural networks for DALK surgical navigation

OBJECTIVE

Corneal disease is one of the main causes of blindness for humans globally nowadays, and deep anterior lamellar keratoplasty (DALK) is a widely applied technique for corneal transplantation. However, the position of stitch points highly influences the success rate of such surgery, which would require accurate control and manipulation of surgical instruments.

METHODS

In this paper, we present a deep learning framework for augmented reality (AR) based surgery navigation to guide the suturing in DALK. It can robustly track the excised corneal contour by semantic segmentation and the reconstruction of occlusion. We propose a novel optical flow inpainting network to recover the missing motion caused by occlusion. The occluded regions are detected by weakly supervised segmentation of surgical instruments and reconstructed by key frame warping along the completed optical flow. Then we introduce two types of loss function to adapt the inpainting network in the optical flow space.

RESULTS

Our techniques are tested and evaluated by a number of real surgery videos from Shandong Eye Hospital in China. We compare our approaches with other typical methods in the corneal contour segmentation, optical flow inpainting and occlusion regions reconstruction. The tracking accuracy reachs 99.2% in average and PSNR reaches 25.52 for the reconstruction of the occluded frames.

CONCLUSION

From the experimental evaluations and user study, both the qualitative and quantitative results indicate that our techniques can achieve accurate detection and tracking of corneal contour under complex disturbance in real-time surgical scenes. Our prototype AR navigation system would be highly useful in clinical practice.

Amniotic Membrane Patch Graft in Management of Double Chamber after Deep Anterior Lamellar Keratoplasty

Purpose

To describe a novel technique of amniotic membrane (AM) patch graft in the management of double chamber treatment after big-bubble deep anterior lamellar keratoplasty (DALK).

Case Report

A 35-year-old male patient with advanced keratoconus underwent big-bubble DALK. Manual lamellar dissection was done due to failed big-bubble. First-day postoperative double chamber was detected. Air bubbling and SF6 injection were tried without any success. Double chamber resolved by fixation of AM transplantation patch graft (1 × 1 mm) over the Descemet's membrane perforation with fibrin glue.

Conclusion

Amniotic membrane patch graft can be used in the management of double chamber after DALK not responsive to intracameral gas injection.

Granular corneal dystrophy recurrence at the posterior graft-host interface after type 1 big bubble deep anterior lamellar keratoplasty

Purpose

To describe our observations of granular corneal dystrophy (GCD) recurrence isolated to the posterior graft-host interface after type 1 big bubble (BB) deep anterior lamellar keratoplasty (DALK).

Observations

We performed a retrospective chart review of 3 eyes in 2 patients, and literature review to summarize GCD recurrence patterns after DALK. A 29-year-old man with GCD underwent DALK by type 1 BB technique. Three years following surgery, he was found to have recurrence of GCD deposits isolated to the posterior graft-host interface. Similarly, a 53-year-old woman with GCD underwent DALK by BB type 1 technique, and was noted to have trace residual deposits at the posterior graft-host interface that increased in number and size over the course of 6 years. Her fellow eye underwent DALK with type 2 BB formation, without evidence of graft-host interface recurrence over a four year period. Our literature review describes the recurrence patterns of 18 cases of GCD following DALK.

Conclusions and importance

DALK can be prone to GCD recurrence in the central posterior graft-host interface. Recurrent deposits isolated to the posterior graft-host interface following type 1 BB DALK supports the hypothesis that GCD recurrence may be due to residual pathologic keratocytes in the pre-Descemet layer (PDL).

Deep anterior lamellar keratoplasty with cross-linked acellular porcine corneal stroma to manage fungal keratitis

PURPOSE

To evaluate the effects of deep anterior lamellar keratoplasty (DALK) with cross-linked acellular porcine corneal stroma (APCS) and post-operative topical tacrolimus treatment in patients with fungal keratitis.

METHODS

This multicenter prospective study involved 25 cases of fungal keratitis that were treated by DALK with cross-linked APCSs and post-operative topical tacrolimus from December 2013 to November 2014 at the Wenzhou Eye Hospital and the Henan provincial Eye Hospital. Signs of post-operative inflammation, corneal reepithelialization, corneal neovascularization, and graft rejection were assessed, and best corrected visual acuity (BCVA), intraocular pressure (IOP), and APCS graft transparency were monitored for the 12-month follow-up period.

RESULTS

All 25 patients underwent DALK without Descemet's membrane perforation. Corneal epithelium recovered completely in 17 patients in the first week, and APCS grafts maintained transparency in 18 patients at 1-year follow-up. The mean BCVA significantly improved from 2.16 ± 0.32 (LogMAR) at baseline to 1.56 ± 0.70 at 1-week (P < .001), 0.95 ± 0.57 at 1-month (P < .001), and 0.70 ± 0.51 at 3-month follow-ups (P < .001). The BCVA kept stable at 6-month and 12-month follow-ups. Post-operative topical tacrolimus alleviated the ciliary injection, except in one case which acute stromal rejection occurred. One patient developed fungal reinfection and underwent penetrating keratoplasty. Graft rejection occurred in three patients. No case was noted with graft splitting, elevated IOP or tacrolimus intolerance.

CONCLUSIONS

DALK using cross-linked APCS combining topical tacrolimus treatment is safe and effective in managing fungal keratitis. It may ameliorate the shortage of corneal donation globally.

[Methods of surgical treatment of keratectasia and analysis of postsurgical quality of vision]

Keratectasias are non-inflammatory dystrophic diseases of the cornea characterized by progressive bilateral thinning of the cornea that lead to deterioration in the quantitative and qualitative characteristics of vision reducing patient's quality of life. The changes can be asymmetrical and destructive. A number of surgeries have been proposed to reduce the negative effects of keratectasia including penetrating keratoplasty and its modifications, implantation of corneal ring segments, corneal cross-linking - alone and in combination with other methods, intrastromal keratoplasty. These methods can improve visual acuity to a certain degree and help slow the progression of keratectasia. This article studies various surgical methods used for treating keratectasia and analyses possible assessment of the quality of vision before and after the treatment.

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.

Descemetocele

A corneal descemetocele, the anterior herniation of an intact Descemet membrane through an overlying stromal defect, is a rare, but serious outcome of progressive corneal ulceration and mandates urgent intervention owing to the imminent risk of perforation. Various ocular and systemic abnormalities that can lead to the formation of descemetocele include microbial keratitis, neurotrophic keratopathy, dry eye disorders, and corneal inflammation associated with immune-mediated disorders. The primary aim of management of a descemetocele remains prompt restoration of ocular integrity to prevent the rupture of the Descemet membrane and further complications. Medical therapy is instituted immediately while deciding on the most suitable operative modality for an individual case. Commonly available treatment options include therapeutic bandage contact lenses, tissue adhesives, amniotic membrane transplantation, corneal patch grafts, penetrating or lamellar keratoplasty, and conjunctival flaps. Infrequently, platelet-rich fibrin membrane grafting and umbilical cord patch transplantation have also been tried with success. The surgical strategy and the outcome are commonly determined by the size, location, and etiology of descemetoceles. Despite the availability of all these treatment options, ambiguity remains about management. We review the available literature on pathogenesis, causes, presentation, differential diagnoses, and management of this disorder and also discuss our experience.

Automated digital analysis of intraoperative keratoscopy and its correlation with postoperative astigmatism after big-bubble deep anterior lamellar keratoplasty

PURPOSE

To investigate the correlation between postoperative corneal astigmatism (PCA) and values of intraoperative keratoscopy analyzed with a newly developed automated technique in patients undergoing big-bubble (BB) deep anterior lamellar keratoplasty (DALK).

METHODS

Photographs of keratoscope rings taken at the end of BB-DALK were analyzed using ImageJ for the calculation of "roundness" (R): values = 1 indicate a perfect circle. Pearson's correlation was used to evaluate the relationship between R and PCA that measured 1 week (V1), 3 months (V2), and 18 months (V3), postoperatively. The area under the curve (AUC) of receiver operating characteristic (ROC) curve was used to evaluate the accuracy of R for identifying patients with PCA < 3 diopters (D). The point on the ROC curve nearest to the coordinate (0,100) was used as a cutoff to determine sensitivity and specificity.

RESULTS

Data from 121 patients were included. The mean value of R*was 0.93 ± 0.04 (range 0.76-0.99). R showed a significant correlation with PA at V3 (R = - 0.42, P < 0.01). The ROC curve had an AUC of 0.69 (95% CI 0.59-0.79). A cutoff value of R = 0.93 had a sensitivity of 70.3% and specificity of 61.0% for identifying patients with PA < 3D at V3.

CONCLUSIONS

This new digital analysis of keratoscope rings allows to identify with reasonably good diagnostic accuracy patients with low values of post-DALK astigmatism correctable with spectacles.

Corneal graft surgery: A monocentric long-term analysis

PURPOSE

To investigate indications, outcomes and changes in clinical patterns of keratoplasty surgery in a Spanish tertiary eye center.

SETTING

Vissum Instituto Oftalmológico, Alicante, Spain.

METHODS

A retrospective review was performed on clinical records of patients that underwent any kind of corneal transplant from 2001 to 2017 in the study center. Inclusion criteria involved the presence of detailed preoperative examination, surgical report and at least 12 months follow-up after the surgery. A statistical analysis was performed on the indications for keratoplasty, survival rates, type of graft failures, and visual outcomes.

RESULTS

A total of 907 keratoplasties procedures were identified. About 432 penetrating keratoplasty (PK), 148 deep anterior lamellar keratoplasty (DALK), and 134 endothelial keratoplasty (EK) met the inclusion criteria. Cumulative survival rate ranged from 94% to 69% in a 1-year period and from 85% to 45% in a 5-years period according to the different graft types. The main cause for failure was immunological rejection for PK, surface diseases for DALK and primary graft failure for EK. Postoperative visual function improved for all the surgical techniques.

CONCLUSION

Corneal transplant is a challenging surgery still complicated by a relevant risk of failure. Our study offers a useful opinion of the current trends on keratoplasty in our country, where the outcomes of the grafts differ considerably in relation to the indications and the different surgical techniques, with lamellar procedures that showed higher rates of success and better visual outcomes than full-thickness grafts.

Indications for intraoperative anterior segment optical coherence tomography in corneal surgery

PURPOSE

Recently, intraoperative optical coherence tomography (iOCT) has evolved in the field of ophthalmic surgery. So far, the use of iOCT was mainly focused to lamellar keratoplasty, especially deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). The aim of this study was to report our experiences with iOCT to introduce new possibilities of this application.

METHODS

We used iOCT in 18 patients who underwent the following surgeries: DALK, DMEK, penetrating keratoplasty, autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens, pannus removal on corneal surface and newborn investigation in Peters' anomaly. We obtained qualitative video data for all procedures.

RESULTS

With the iOCT, the cannula placement during DALK preparation of the recipient cornea and bubble formation could be visualized to improve the success rate of the big bubble injection. In DMEK, the iOCT enables the visualization of Descemet's membrane removal in the recipient and graft orientation as well as better control of graft attachment. The iOCT enables intraoperative visualization of the graft-host interface during penetrating keratoplasty. During autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens and removal of corneal surface pannus the iOCT is capable of showing the thickness of lamellar preparations to avoid penetrations and to save healthy recipient's tissue.

CONCLUSION

The iOCT is a helpful device for intraoperative anterior segment imaging not only for DALK and DMEK. It is also beneficial in penetrating keratoplasty and every other form of lamellar preparation during corneoscleral surgery.

Manual deep anterior lamellar keratoplasty after partial unintentional full-thickness trephination

PURPOSE

The aim of this study was to describe a surgical technique to perform deep anterior lamellar keratoplasty (DALK) despite inadvertent full thickness trephination in one quadrant.

METHODS

Case report of a 19-year-old boy who underwent DALK for visually significant post-infectious stromal scar in his left eye. An unintentional full thickness trephination occurred in the upper-nasal quadrant at the beginning of the surgery. After suturing the perforated area, manual DALK was performed, and an air bubble was left in the anterior chamber. Evaluated outcomes included best spectacle corrected visual acuity (BSCVA), residual recipient bed thickness, endothelial cell count (ECC), graft clarity, rejection, and presence/absence of double anterior chamber.

RESULTS

The surgery was completed without any further complications. No double anterior chamber or Urrets-Zavalia syndrome was observed on the first postoperative day. Mean residual recipient bed thickness was 72 μm and regular. ECC was 2446 cell/mm². BSCVA at 18 months of follow-up was 0.9. There were no episodes of rejection, and the graft remained clear at the last follow-up (4 years).

CONCLUSION

Inadvertent partial full thickness trephination of the recipient cornea is a largely preventable but possible complication during DALK. Penetrating keratoplasty conversion can be avoided by performing a manual dissection DALK.

Comparison of corneal biomechanical properties following penetrating keratoplasty and deep anterior lamellar keratoplasty for keratoconus

IMPORTANCE

Keratoplasty is a surgical procedure to create a more regular optical surface following biomechanical weakening of the cornea in keratoconus. The ideal keratoplasty procedure should also restore corneal biomechanics to that of the healthy cornea.

BACKGROUND

This study aimed to evaluate and compare the biomechanical properties of corneas following penetrating keratoplasty (PKP) and predescematic deep anterior lamellar keratoplasty (DALK) to those of healthy eyes.

DESIGN

Prospective cross-sectional study.

PARTICIPANTS

Two cohorts of post-keratoplasty eyes (42 eyes with PKP and 27 eyes with DALK) with each other, and with a cohort of 152 healthy eyes.

METHODS

All eyes were examined by slit-lamp biomicroscopy, tomography, anterior segment-OCT and non-contact tonometry CorVis ST (CST).

MAIN OUTCOME MEASURES

CST biomechanical parameters, maximum corneal deformation (MCD) and corneal energy dissipation were compared between keratoplasty techniques, and with healthy eyes.

RESULTS

The mean age of participants with PKP and DALK were 35 ± 13.7 and 36.1 ± 12.6 years, respectively. None of the CST parameters were significantly different between PKP and DALK eyes. However, when compared to healthy corneas, numerous parameters were significantly different for both keratoplasty techniques. Of note, MCD was significantly higher in PKP compared to DALK and healthy corneas, after controlling for co-factors.

CONCLUSIONS AND RELEVANCE

Neither type of keratoplasty technique utilized in keratoconus completely restored corneal biomechanical properties to that of healthy corneas. However, PKP resulted in a greater number of parameters significantly different to healthy corneas, compared to DALK.

Novel Technique For The Management Of Macroperforation During Deep Anterior Lamellar Keratoplasty

Purpose

To describe the outcomes of a case series of patients who underwent a novel technique for managing macroperforation during deep anterior lamellar keratoplasty (DALK).

Methods

Nine eyes of 9 patients with advanced keratoconus who underwent DALK comprised the case series. A macroperforation occurred in all eyes during DALK. The stromal patch suturing technique was used to manage all cases; a large piece of the previously excised stromal tissue was sutured to the edge of the trephine to seal the perforation. The technical aspects of the procedure are described and data are presented on the visual outcomes, endothelial microscopy, and postoperative complications at last postoperative visit (average 18 months; range, 7 to 23 months).

Results

All 9 cases were managed successfully with the stromal patch suturing technique. Postoperatively, the graft was clear in all cases. At day 1, seven eyes had a Descemet’s membrane detachment, 3 of these eyes resolved spontaneously within 2 weeks and 4 required air bubble injection for successful reattachment. At last follow up seven eyes had a corrected distance visual acuity of 20/30 or better and 2 eyes had 20/40 vision. The average endothelial cell count was 2162 cell/mm². There were no cases with excessive inflammation or vascularisation during the postoperative follow-up.

Conclusion

The stromal patch suturing technique was successfully used to manage intraoperative macroperforation during DALK. This technique resulted in endothelial changes that were consistent with uncomplicated DALK and function visual acuity of 20/40 or better in all cases with no postoperative sequelae.

Immune reactions after modern lamellar (DALK, DSAEK, DMEK) versus conventional penetrating corneal transplantation

In the past decade, novel lamellar keratoplasty techniques such as Deep Anterior Lamellar Keratoplasty (DALK) for anterior keratoplasty and Descemet stripping automated endothelial keratoplasty (DSAEK)/Descemet membrane endothelial keratoplasty (DMEK) for posterior keratoplasty have been developed. DALK eliminates the possibility of endothelial allograft rejection, which is the main reason for graft failure after penetrating keratoplasty (PK). Compared to PK, the risk of endothelial graft rejection is significantly reduced after DSAEK/DMEK. Thus, with modern lamellar techniques, the clinical problem of endothelial graft rejection seems to be nearly solved in the low-risk situation. However, even with lamellar grafts there are epithelial, subepithelial and stromal immune reactions in DALK and endothelial immune reactions in DSAEK/DMEK, and not all keratoplasties can be performed in a lamellar fashion. Therefore, endothelial graft rejection in PK is still highly relevant, especially in the "high-risk" setting, where the cornea's (lymph)angiogenic and immune privilege is lost due to severe inflammation and pathological neovascularization. For these eyes, currently available treatment options are still unsatisfactory. In this review, we will describe currently used keratoplasty techniques, namely PK, DALK, DSAEK, and DMEK. We will summarize their indications, provide surgical descriptions, and comment on their complications and outcomes. Furthermore, we will give an overview on corneal transplant immunology. A specific focus will be placed on endothelial graft rejection and we will report on its incidence, clinical presentation, and current/future treatment and prevention options. Finally, we will speculate how the field of keratoplasty and prevention of corneal allograft rejection will develop in the future.

Management of dislocated nucleus with corneal opacity by combined deep anterior lamellar keratoplasty, pars- plana vitrectomy and phaco-fragmentation

A 32-year-old man presented with bilateral diminution of vision for 10 years. Visual acuity was light perception in both eyes with inaccurate projection in the oculus dextrus(OD) and accurate projection in the in oculus sinister (OS). Intraocular pressure was 6 and 12 mm Hg in the OD and OS, respectively. Slit-lamp examination revealed the presence of leucomatous corneal opacification with microcornea in oculus uterque (OU). Both eyes had a dislocated nucleus in the vitreous cavity on ultrasound B-scan with advanced cupping in the right eye. Ultrasound biomicroscopy revealed ciliary body atrophy in the OD and preserved ciliary processes (two quadrants) in the OS. In view of a partially preserved ciliary body function and a potential for gaining useful vision, we planned surgical intervention in the left eye. Deep anterior lamellar keratoplasty with pars planavitrectomy (PPV) and phacofragmentation of the nucleus was done. Donor lamellar graft was sutured after completion of PPV and nucleus fragmentation. The patient regained useful ambulatory vision postoperatively with clear corneal graft.

Factors Affecting Formation of Type-1 and Type-2 Big Bubble during Deep Anterior Lamellar Keratoplasty

Purpose: To determine the factors associated with the formation of different types of big bubble (BB) during DALK. Methods: In this retrospective study, 322 consecutive eyes of 307 patients with corneal stromal disorders who underwent DALK between January 2014 and June 2017 were included. Age, sex, corneal pathology, visual acuity, corneal curvature, corneal thickness, and adverse events were recorded. The main outcome measure was the success of BB formation with respect to the corneal pathology. Results: Type-1 BB was achieved in 147 eyes (45.7%), whereas type-2 BB was formed in 109 eyes (33.9%). The overall success rate of BB formation was 82.9%. Type-1 BB formation in keratoconus patients was significantly higher than type-2 BB (83.8% vs 2.6%, p < 0.001). In contrast, type-2 BB formation was significantly higher than type-1 BB (61.0% vs 15.6%, p < 0.001) in patients with corneal scars. Type-1 BB was more likely to be seen in patients with superficial corneal scarring, granular, and lattice dystrophies, while corneas with deep scarring and macular dystrophy had more type-2 BB. The type of bubble was not associated with age and gender of the patients. Conclusions: The overall success of big-bubble (BB) deep anterior lamellar keratoplasty (DALK) depends on the preoperative corneal pathology. Type -1 BB was more commonly seen in keratoconus patients whereas type-2 BB was observed in patients with deep corneal scars and other corneal pathologies affecting deeper layers of corneal stroma.

Deep anterior lamellar keratoplasty: A surgeon's guide

Purpose

To review and highlight important practical aspects of deep anterior lamellar keratoplasty (DALK) surgery and provide some useful tips for surgeons wishing to convert to this procedure from the conventional penetrating keratoplasty (PK) technique.

Methods

In this narrative review, the procedure of DALK is described in detail. Important pre, intra, and postoperative considerations are discussed with illustrative examples for better understanding. A comprehensive literature review was conducted in PubMed/Medline from January 1995 to July 2017 to identify original studies in English language regarding DALK. The primary endpoint of this review was the narrative description of surgical steps for DALK, its pitfalls, and management of common intraoperative complications.

Results

A standard DALK procedure can be successfully performed taking into consideration factors such as age, ophthalmic co-morbidities, status of the crystalline lens, retina, and intraocular pressure. Careful trephination and dissection of the host cornea employing appropriate technique (such as big bubble technique, manual dissection, visco-dissection, etc.) suitable for the specific case is important to achieve good postoperative outcomes. Prompt identification of intraoperative complications such as double bubble, micro and macroperforations, etc. are vital to change the management strategies.

Conclusion

Although there is a steep learning curve for DALK procedure, considering details and having insight into the management of intraoperative issues facilitates learning and reduces complication rates.

An unusual case of acute angle-closure glaucoma following deep anterior lamellar keratoplasty using the "big bubble" technique

Purpose

To report the first case of acute angle closure due to a high-pressure Descemet membrane detachment following deep anterior lamellar keratoplasty (DALK) using the “big bubble” technique.

Observations

A 25-year-old man underwent DALK surgery for keratoconus using the “big bubble” technique in which an air bubble is injected in deep stroma to promote dissection of underlying Descemet membrane from stroma. Surgery was uneventful and the patient was discharged home in good conditions. On post-operative day 1, the patient came back with severe periocular pain. Intra-ocular pressure was found to be 38 mmHg. Anterior-segment OCT revealed a “double anterior chamber” created by a high-pressure Descemet detachment that was occluding the pupil and causing secondary acute angle closure glaucoma. The patient was brought back promptly to the operating room where the high-pressure chamber was properly evacuated, allowing Descemet membrane to properly reattach to stroma.

Conclusions and importance

Inability to recognize stroma from Descemet membrane during the dissection of the “big bubble technique” can result in failure to evacuate the high-pressure Descemet membrane detachment, putting the patient at risk for acute angle closure glaucoma from occlusion of the pupil. Proper dissection of stroma from underlying DM is a challenging and crucial step in the “big bubble” technique. Several methods, such as the injection of small bubbles in the anterior chamber or the use of intra-operative anterior segment OCT could be employed to prevent such a complication.

Impact of donor graft quality on deep anterior lamellar Keratoplasty (DALK)

Background

To evaluate main features of donor tissue that may influence clinical outcome or complication rate after deep anterior lamellar keratoplasty (DALK).

Methods

Donor tissue parameters of 84 consecutive corneal donor grafts used for big-bubble DALK surgery between June 2011 and December 2014 in 84 eyes of 84 patients with disorders of anterior corneal stroma were correlated to clinical outcome parameters of recipient eyes 12 months after surgery and 3 months after total suture removal. Main donor tissue parameters included age), post-mortem time, overall preservation time, preservation time after split and prior to transplantation, and preservation technique. Clinical outcome parameters included best spectacle corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD) and complication rates. Pearson’s correlation, linear regression analysis for clinical outcome parameter and logistic regression analysis for postsurgical complication rates were applied.

Results

Corneal donors were mean aged 67.4 ± 12.5 years with a post-mortem time of 20.7 ± 14.7 h and ECD of 2641.0 ± 362.8 cells/mm². Overall preservation time was 16.3 ± 6.3 days. Recipients showed mean BSCVA 12 months postoperatively of 0.60 ± 0.36 logMAR, endothelial cell loss was 4 ± 16%, and central corneal thickness was 571.7 ± 54.2 μm. 3 months after total removal of sutures, BSCVA was 0.20 ± 0.10 logMAR, endothelial cell loss was 17 ± 24%, and central corneal thickness was 590.9 ± 55.5 μm. Loosening of sutures occurred in 20%, and Descemet detachment in 16%. None of the clinical outcome parameters or complication rate after DALK showed a significant association with donor tissue parameters.

Conclusions

Donor corneas, independent of excision techniques or preservation method, with donor age ≤ 88 years, post-mortem time ≤ 63 h, overall preservation time ≤ 14 days for cold storaged donor tissue and ≤35 days for organ culture, and preservation time after split prior to grafting ≤96 h, seem to be applicable as safe donor tissue for DALK surgery.

Traumatic globe rupture after deep anterior lamellar keratoplasty-A novel management technique

A traumatic wound dehiscence can occur many years after surgery in 2-6% of all keratoplasties. Intraocular tissue prolapse can lead to severe visual loss. Deep anterior lamellar keratoplasty (DALK) leads to higher wound stability because of the intact Descemet membrane. We report a case of a novel management of wound dehiscence following DALK. A 59-year-old patient underwent uncomplicated DALK for advanced keratoconus. Eighteen months later he experienced a traumatic wound dehiscence (globe rupture) after a fall. Visual acuity decreased to light perception on the affected eye, the iris and prolapsed vitreous were incarcerated, and no retinal details were recognizable. The corneal graft was dehiscent over eight clock hours, the Descemet membrane was ruptured, and the stroma dissolved over 30% of its surface in a bell shape. Primary wound closure was performed with nylon 10-0 single interrupted corneal sutures. One day after emergency treatment, a 23-gauge pars-plana-vitrectomy for vitreous hemorrhage was conducted and a retinal tear was treated with laser photocoagulation. The Descemet membrane was repositioned using a 23 g vitrectomy probe under air and the globe was filled with SF₆ gas. Postoperatively, visual acuity increased to 6/15 and the cornea cleared up. Corneal graft and Descemet membrane repositioning after trauma can avoid a further keratoplasty and the risk of immunological rejection of donor endothelial cells. Clin. Anat. 31:56-59, 2018. © 2017 Wiley Periodicals, Inc.

Systematic review comparing penetrating keratoplasty and deep anterior lamellar keratoplasty for management of keratoconus

AIM

Perception of reduced incidence of graft rejection after deep anterior lamellar keratoplasty (DALK) has attracted many surgeons towards this technique in keratoconus. This review aims to compare the visual, refractive and graft outcomes after penetrating keratoplasty (PK) and DALK for keratoconus.

METHODS

Electronic searches of PubMed, MEDLINE, EMBASE, Latin American and Caribbean Health Sciences Literature database (LILACS), metaRegister of Controlled Trials (mRCT), ClinicalTrial.gov and the WHO International Clinical Trials Registry Platform (ICTRP) were performed. We included randomized control trials (RCTs) and comparative studies to assess primary and secondary outcomes after PK and DALK in eyes with keratoconus. Primary outcome was best-corrected visual acuity (BCVA) LogMAR at ≥6 months. Secondary outcomes included number of patients with BCVA≥0 LogMAR, uncorrected visual acuity (UCVA) LogMAR, spherical equivalent (SE), refractive and keratometric astigmatism, endothelial cell density (ECD) cell/mm², graft rejection and graft survival.

RESULTS

Eighteen studies (including 2 RCTs) compared DALK (965 eyes) and PK (2402 eyes) for keratoconus. There was strong evidence through RCTs suggesting better LogMAR BCVA at ≥6 months and better LogMAR UCVA with PK; reduced refractive astigmatism and rejection with DALK and no difference in SE and keratometric astigmatism. Moreover, there was weak evidence to suggest better BCVA≥0 LogMAR after PK and no difference in ECD between the two techniques.

CONCLUSIONS

Despite the popularity of DALK amongst corneal surgeons for keratoconus, there is a paucity of high quality RCTs. The existing limited evidence confirms reduced rejection and refractive astigmatism with DALK but better visual outcomes with PK. Internationally agreed data sets and follow-up protocol are warranted.