[The penetrating keratoplasty. A 100-year success story]

Different Course of Immune Reactions and Endothelial Cell Loss after Penetrating Low-Risk Keratoplasty and Descemet Membrane Endothelial Keratoplasty for Fuchs Endothelial Dystrophy

BACKGROUND

The aim of this study was to compare the incidence of immune reactions and endothelial cell loss after penetrating keratoplasty (PKP) vs. Descemet membrane endothelial keratoplasty (DMEK) in patients with Fuchs endothelial dystrophy (FED).

PATIENTS AND METHODS

In the present retrospective study, a total of 962 surgeries (225 excimer laser PKP and 727 DMEK) of 700 patients performed between 28.06.2007 and 27.08.2020 in the Department of Ophthalmology at Saarland University Medical Center UKS were statistically evaluated. On the one hand, the prevalence and the temporal course of the immune reactions that occurred were analysed using the Kaplan-Meier method, as well as the effect of the immune reactions on the endothelial cells and corneal thickness. Secondly, endothelial cell density, pleomorphism, and polymegethism of the endothelial cells were evaluated for the time points U1 = preoperative, U2 = 6 weeks postoperative, U3 = 6 to 9 months postoperative, U4 = 1 to 2 years postoperative, and U5 = 5 years postoperative. In addition, statistical tests were carried out for differences between the two types of surgery and in the longitudinal course.

RESULTS

A total of 54 immune reactions occurred during the observed period, whereby the probability of such a reaction was significantly greater in the PKP group with 8.9% than in the DMEK group with 4.5% (p = 0.011). The comparison of the two Kaplan-Meier curves also showed a significant difference between the two surgical techniques in the log-rank test (p = 0.012). The endothelial cell loss due to the immune reaction was only significant in PKP (p = 0.003). For all surgical procedures, endothelial cell density decreased significantly with time in both surgical techniques (p < 0.0001 in each case), but more strongly with DMEK than with PKP (p < 0.0001). Furthermore, this cell density was significantly higher with PKP than with DMEK for the whole observation time (p < 0.0001). Polymegethism decreased significantly in the DMEK group (p < 0.0001). Pleomorphism was significantly higher, on average, in DMEK than in PKP (p < 0.0001).

CONCLUSION

The prognosis of DMEK in patients with FED seems to be more favourable after immune reactions than that of PKP, as not only were immune reactions less frequent, but they were also milder. However, endothelial cell density was significantly higher in the PKP group during the entire follow-up.

[Immune reaction after penetrating keratoplasty depending on graft size and centration]

BACKGROUND

Immune reaction (IR) after penetrating keratoplasty (PKP) is a serious complication with a high risk of graft failure. The aim of this study was to analyze and evaluate the risk factors for IR, in particular, the influence of graft size and centration.

PATIENTS AND METHODS

A total of 2133 patients who underwent PKP between January 2009 and July 2019 were included in this retrospective study. The following endpoints were analyzed: frequency of IR, graft origin, donor and patient age, diagnosis, corneal diameter and ratio of the graft size to the recipient cornea size. In addition, the role of graft centration, with the help of distance measurements of the graft margins to the vascularized limbus at four locations, was investigated in detail.

RESULTS

Overall, 8.25% of patients suffered from IR during the observational period. The frequency of IR was significantly correlated (p < 0.001) with the ratio of the graft size to the recipient cornea size. In addition, a statistically significant correlation was found between the occurrence of IR and a small distance to the limbal margins in the Y‑axis (inferior and superior). In particular, the correlation coefficient was larger at the inferior limbus (p < 0.001).

CONCLUSION

An IR after PKP is a not uncommon complication and is significantly related to graft size and centration. A large graft chosen in relation to the recipient cornea and the proximity of the graft to the vascularized limbus at the inferior and superior sites significantly correlate with the occurrence of IR. These are important risk factors for graft survival, which can be influenced by the corneal microsurgeon and could possibly be further optimized in the future.

Need for explantation of an intrastromal titan ring after penetrating keratoplasty in two patients

The most severe complications after penetrating keratoplasty (PKP) include high astigmatism and immunological graft reaction. The introduction of the corneal intrastromal titan ring by Krumeich intended to reduce the incidence of both complications. We present two patients with keratoconus who referred to our department after a PKP combined with the implantation of an intrastromal ring. The first patient suffered from bulbar pain and headaches. The second patient suffered from postoperative high myopia, irregular astigmatism and was contact lens intolerant. In the first patient we recognized anterior movement of the ring inside the stroma and decided to remove it. The second patient was found to have extreme bulging of the transplant. We removed the ring and sequentially performed a repeat-PKP. In both patients the implantation of the ring failed to decrease the postoperative astigmatism and caused symptoms that affected the patients’ everyday life. Therefore, we recommend not to use this titan ring.

Penetrating Excimer Laser Keratoplasty with vs without the Homburg Cross-Stitch Marker in Inexperienced Surgeons

BACKGROUND AND OBJECTIVES

The Homburg cross-stitch marker, according to Suffo, was developed in 2017 in the Department of Ophthalmology at Saarland University Medical Center. With this instrument, a surgeon can precisely define and mark the points of the first and second continuous cross-stitch sutures, according to Hoffmann. The aim of this retrospective study was to compare the functional outcomes of Hoffmann's double continuous cross-stitch suture in penetrating keratoplasty (PKP) with vs without the Homburg cross-stitch marker in inexperienced surgeons.

METHODS

A total of 130 eyes from 130 patients with central corneal scars, corneal dystrophies and advanced keratoconus were included. All eyes underwent elective excimer laser-assisted penetrating keratoplasty (excimer laser PKP) with a diameter of 8.0/8.1mm. In 65 eyes each, surgery was performed without (group 1) or with (group 2) the Homburg cross-stitch marker. Corrected distance visual acuity, topographic astigmatism, and refractive cylinder were obtained 6 weeks, 10 months post-PKP as well as 6 weeks after the first and after the second suture removal, respectively. The rate of early postoperative single interrupted suture addition was compared between the two groups.

RESULTS

Visual acuity, astigmatism and refractive cylinder values were significantly more favorable in group 2 (with device) compared to group 1 (without device) before and after suture removal. Postoperative single interrupted suture addition was performed in 34.4% of patients in group 1 compared to 10.6% in group 2 (P = 0.001, Fisher's Exact Test).

CONCLUSION

The use of the Homburg cross-stitch marker for excimer laser PKP in young cornea specialists results in significantly better visual acuity before and after suture removal, significantly lower astigmatism and cylinder value before suture removal, as well as a reduced necessity of early postoperative single interrupted suture addition.

Post-penetrating keratoplasty astigmatism

Postoperative astigmatism is one of the common complications affecting visual outcomes after a penetrating keratoplasty. It can result from various factors related to host, donor and surgical technique, resulting in suboptimal visual outcome. While some of the measures taken during preoperative planning and during actual surgery can reduce the magnitude of postoperative astigmatism, postoperative correction of astigmatism is often required in cases with high degrees of astigmatism. When spectacles and contact lenses fail to provide optimal visual outcomes, various surgical techniques that include astigmatic keratotomy, compression sutures, toric intraocular lens placement, and laser refractive procedures can be considered. When none of these techniques are able to achieve a desired result with in the acceptable optical range, a repeat keratoplasty is considered a last option. We discuss the various causes and management of complication of postoperative astigmatism occurring after a full thickness corneal transplantation surgery.

[Partial visual rehabilitation 5 and 6 years after a Gundersen total conjunctival flap procedure]

BACKGROUND

We present the results of penetrating keratoplasty (PKP) after previous treatment with a total conjunctival flap in two patients.

CASE REPORTS

Patient 1, a 66-year-old with a history of bilateral cement chemical burn in 1986 and external right-sided limbokeratoplasty in 2008 was treated externally with a total conjunctival flap in the right eye in 2014 due to a persistent corneal ulcer with imminent perforation. Best-corrected visual acuity (BCVA) in the right eye was light sensation, intraocular pressure on palpation was within normal range. Clinically, total conjunctival flap was present. Patient 2 was treated externally in May 2015 due to acanthamoeba keratitis in the left eye with a deep anterior lamellar keratoplasty (DALK). A re-DALK was also performed externally in the same month. A third DALK was performed externally in August 2015 due to a persistent corneal ulcer, followed by a total conjunctival flap 2 weeks later. BCVA of the left eye was light sensation and intraocular pressure on palpation was within the normal range.

RESULTS

Patient 1 was treated with removal of the conjunctival flap in the right eye and penetrating central re-keratoplasty (hand-held Barron trephine; graft diameter 8.5/8.75 mm). Simultaneously, lens extraction and intraocular lens implantation were performed (as a triple procedure). Additionally, amniotic membrane transplantation (AMT) as patch and a temporal lateral tarsorrhaphy were performed. BCVA 6 months postoperatively was 0.1. The graft was clear, without any signs of rejection. Patient 2 was treated on the left eye with removal of the conjunctival flap and a penetrating central keratoplasty (hand-held Barron trephine; graft diameter 7.0/7.5 mm). An AMT as patch and a temporal lateral tarsorrhaphy were simultaneously performed. Cataract surgery was performed 3 months postoperatively and BCVA of the right eye was 0.1 thereafter. The graft was clear, without any signs of rejection.

CONCLUSION

The conjunctival flap is a treatment of last resort of the (almost) penetrated corneal ulcer, which is to be used only when a keratoplasty is technically impossible. Provided the eye structure and retinal function are preserved, partial visual rehabilitation can possibly be achieved through a PKP after excision of the conjunctival flap, even years after corneal blindness.

Eye Banks: Future Perspectives

Technological progress and societal change are transforming medicine, and cornea banks are no exception. New infectiological factors, statutory requirements, management concepts, globalisation and digitalisation are also influencing how such facilities will operate in the future. The goal of providing high quality material to patients with corneal disease remains unaltered. The present article seeks to shed light on the type of material this will involve and under what circumstances it is to be obtained.

The Homburg Cross-Stitch Marker for Double-Running Sutures in Penetrating Keratoplasty

INTRODUCTION

Until now, the double-running cross-stitch according to Hoffmann used in penetrating keratoplasty (PKP) has been routinely carried out by simply using a sense of proportion. As a result, the estimation of the precisely defined entry and exit points of the sutures and, by extension, the success of the running cross-stitch suture was completely dependent on the practical experience of the surgeon. Therefore, we introduced the cross-stitch marker as a supporting instrument for PKP surgery.

METHODS

Description of the Homburg cross-stitch marker with an exact step-by-step guide on how the instrument is implemented while performing a PKP to mark entry and exit points for sutures including a video to demonstrate the use of this instrument.

RESULTS

The new Homburg cross-stitch marker ensures the precise localisation of the entry and exit points of the suture. This new instrument allows inexperienced surgeons in particular to feel very confident when performing the running sutures.

CONCLUSION

Surgeons with little experience can completely avoid using their still imprecise sense of proportion and significantly shorten the learning curve for this procedure.

Descemet's Membrane Endothelial Keratoplasty with Split Corneal Grafts: The Influence of Tamponade Material and Endothelial Storage Time

Purpose: The aim of this study was to describe the clinical outcome of Descemet's membrane endothelial keratoplasty (DMEK) performed with split corneal grafts and to evaluate the influence of tamponade material and endothelial storage time on DMEK success. Material and Method: The records of 43 patients who underwent DMEK surgery with a split corneal graft were reviewed. Diagnosis of the patients, preoperative and postoperative best-corrected visual acuity (BCVA), corneal and endothelial storage time, tamponade material, complications, and success rates were specifically tabulated. Results: The most common indication for DMEK was pseudophakic bullous keratopathy (n = 25, 58.2%). Re-bubbling was needed in 10 cases (23.2%), and a re-DMEK was scheduled in 2 cases and penetrating keratoplasty in 4 cases (9.3%). BCVA improved significantly postoperatively (p < .001). There was an insignificant trend towards a lower re-bubbling rate and better long-term anatomic outcome in favor of 20% SF6 group compared to air tamponade (p = .18 and p = .25). There was no significant difference between the early endothelial transplant (<24 h) and delayed endothelial transplant (3 to 14 days) groups for anatomic success, corneal thickness or BCVA (p = .94, p = .13 and p = .35). Conclusion: The success rate of DMEK was satisfactory with split corneal grafts. There was no adverse influence of delayed endothelial transplantation on clinical outcome. The success rate of 20% SF6 tamponade was slightly better than room air.

Penetrating Keratoplasty for Keratoconus - Excimer Versus Femtosecond Laser Trephination

BACKGROUND

In case of keratoconus, rigid gas-permeable contact lenses as the correction method of first choice allow for a good visual acuity for quite some time. In a severe stage of the disease with major cone-shaped protrusion of the cornea, even specially designed keratoconus contact lenses are no more tolerated. In case of existing contraindications for intrastromal ring segments, corneal transplantation typically has a very good prognosis.

METHODS

In case of advanced keratoconus - especially after corneal hydrops due to rupture of Descemet's membrane - penetrating keratoplasty (PKP) still is the surgical method of first choice. Noncontact excimer laser trephination seems to be especially beneficial for eyes with iatrogenic keratectasia after LASIK and those with repeat grafts in case of "keratoconus recurrences" due to small grafts with thin host cornea. For donor trephination from the epithelial side, an artificial chamber is used. Wound closure is achieved with a double running cross-stitch suture according to Hoffmann. Graft size is adapted individually depending on corneal size ("as large as possible - as small as necessary"). Limbal centration will be preferred intraoperatively due to optical displacement of the pupil. During the last 10 years femtosecond laser trephination has been introduced from the USA as a potentially advantageous approach.

RESULTS

Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient centration, reduces "vertical tilt" and "horizontal torsion" of the graft in the recipient bed, thus resulting in significantly less "all-sutures-out" keratometric astigmatism (2.8 vs. 5.7 D), higher regularity of the topography (SRI 0.80 vs. 0.98) and better visual acuity (0.80 vs. 0.63) in contrast to the motor trephine. The stage of the disease does not influence functional outcome after excimer laser PKP. Refractive outcomes of femtosecond laser keratoplasty, however, resemble that of the motor trephine.

CONCLUSIONS

In contrast to the undisputed clinical advantages of excimer laser keratoplasty with orientation teeth/notches in keratoconus, the major disadvantage of femtosecond laser application is still the necessity of suction and applanation of the cone during trephination with intraoperative pitfalls and high postoperative astigmatism.

Optical coherence tomography-based topography determination of corneal grafts in eye bank cultivation

Vision loss due to corneal injuries or diseases can be treated by transplantation of human corneal grafts (keratoplasty). However, quality assurance in retrieving and cultivating the tissue transplants is confined to visual and microbiological testing. To identify previous refractive surgery or morphological alterations, an automatic, noncontact, sterile screening procedure is required. Twenty-three corneal grafts have been measured in organ culture with a clinical spectral-domain optical coherence tomographer. Employing a biconic surface fit with 10 degrees of freedom, the radii of curvature and conic constants could be estimated for the anterior and posterior corneal surfaces. Thereupon, central corneal thickness, refractive values, and astigmatism have been calculated. Clinical investigations are required to elaborate specific donor–host matching in the future.

[The German Acanthamoeba keratitis register: Initial results of a multicenter study]

BACKGROUND AND PURPOSE

In September 2011 the cornea section of the German Ophthalmological Society (DOG) established the first German Acanthamoeba keratitis registry. The data of this multicenter survey are being collected, compiled and evaluated at the Department of Ophthalmology at the Saarland University. The aim of this article is to present an intermediate report.

PATIENTS AND METHODS

Data from 172 eyes with Acanthamoeba keratitis were collected during the last 10 years. For this interim report we actually evaluated 121 eyes (60.2 % female patients, average age 41.3 years) and collected the following data: date of onset of symptoms, date and method of diagnosis, initial diagnosis, anamnestic data, clinical symptoms and signs at diagnosis and during follow-up, conservative and surgical therapy. Criteria for inclusion in the Acanthamoeba registry was the established diagnosis of an Acanthamoeba keratitis with at least one of the methods described in this article.

RESULTS

Acanthamoeba keratitis could be histologically proven in 55.3 % of the cases, via PCR in 25.6 %, with confocal microscopy in 20.4 % and using in vitro cultivation in 15.5 %. Clinical symptoms and signs in Acanthamoeba keratitis were pain in 67.0 %, ring infiltrates in 53.4 %, pseudodendritiform epitheliopathy in 11.7 % and keratoneuritis in 5.8 %. In 47.6 % of the cases the initial diagnosis was herpes simplex virus keratitis followed by bacterial keratitis in 25.2 % and fungal keratitis in 3.9 %. Acanthamoeba keratitis was the correct initial diagnosis in only 23.2 % of cases. The average time period between first symptoms and diagnosis was 2.8 ± 4.0 months (range 0-23 months). A triple therapy with Brolene® Lavasept® and antibiotic eye drops at least 5 ×/day was used in 54.5 % of eyes (n = 66). Penetrating keratoplasty was performed in 40.4 %, in 18 cases in combination with cryotherapy of the cornea. The mean graft diameter was 7.9 ± 1.1 mm (range 3.5-11.0 mm). The final visual acuity (Snellen visual acuity chart at 5 m) was comparable in the two groups of eyes with (5/40 ± 5/25) and without (5/32 ± 5/25) keratoplasty.

CONCLUSION

Acanthamoeba keratitis is a rare and often very late diagnosed disease and two thirds of the cases were initially misdiagnosed. The early recognition of the typical symptoms is crucial for the prognosis of the disease. All ophthalmological departments in Germany are invited to submit further data of all confirmed cases (berthold.seitz@uks.eu), whether retrospectively or prospectively in order to generate an adequate standardized diagnostic and therapeutic approach for this potentially devastating disease.

[Perspectives of laser-assisted keratoplasty: current overview and first preliminary results with the picosecond infrared laser (λ = 3 µm)]

BACKGROUND

This article provides a review of the current state of laser-assisted keratoplasty and describes a first proof of concept study to test the feasibility of a new mid-infrared (MIR) picosecond laser to perform applanation-free corneal trephination.

METHODS

The procedure is based on a specially adapted laser system (PIRL-HP2-1064 OPA-3000, Attodyne, Canada) which works with a wavelength of 3,000 ± 90 nm, a pulse duration of 300 ps and a repetition rate of 1 kHz. The picosecond infrared laser (PIRL) beam is delivered to the sample by a custom-made optics system with an implemented scanning mechanism. Corneal specimens were mounted on an artificial anterior chamber and subsequent trephination was performed with the PIRL under stable intraocular pressure conditions.

RESULTS

A defined corneal ablation pattern, e.g. circular, linear, rectangular or disc-shaped, can be selected and its specific dimensions are defined by the user. Circular and linear ablation patterns were employed for the incisions in this study. Linear and circular penetrating PIRL incisions were examined by macroscopic inspection, histology, confocal microscopy and environmental scanning electron microscopy (ESEM) for characterization of the incisional quality. Using PIRL reproducible and stable incisions could be made in human and porcine corneal samples with minimal damage to the surrounding tissue.

CONCLUSION

The PIRL laser radiation in the mid-infrared spectrum with a wavelength of 3 µm is exactly tuned to one of the dominant vibrational excitation bands of the water molecule, serves as an effective tool for applanation-free corneal incision and might broaden the armamentarium of corneal transplant surgery.

[Astigmatism after keratoplasty: influence of orthotopic transplantation]

BACKGROUND

Patients undergoing corneal transplantation often suffer from postoperative reduced vision due to high astigmatism. This retrospective study analyzed the influence of heterotopic or orthotopic transplantation on astigmatism and visual outcome.

PATIENTS AND METHODS

In this study 373 eyes of 334 patients were analyzed. Group 1 (OT) contained 186 eyes, which underwent orthotopic transplantation (side of recipient and donor corresponded), whereas group 2 (HT) included 187 heterotopic keratoplasties (donor cornea placed in the recipient's contralateral side). After 1, 3, 6, 12 and 24 months the median of keratometric astigmatism, objective astigmatism, topographic astigmatism and best corrected visual acuity (BCVA) were assessed and compared between groups.

RESULTS

The long-term results showed no statistically significant differences regarding keratometric and objective astigmatism, whereas topographic astigmatism differed significantly (p = 0.04) after 3 months. We observed a lower astigmatism of 5.7 dpt (range 3.08-7.78 dpt) in group OT than in the group HT with 7.1 dpt (range 3.9-10.7 dpt). No differences were found at the other time points. The BCVA showed a significantly better effect after 1 month (p = 0.01) in the OT group of 0.2 (0.1-0.3) than in HT group of 0.1 (0.05/0.25). In the postoperative course no additional significant dissimilarities were documented.

CONCLUSIONS

Heterotopic and orthotopic keratoplasty show no significant long-term differences in astigmatism and visual outcom.

[DALK and penetrating laser keratoplasty for advanced keratoconus]

BACKGROUND

In cases of contact lens intolerance and/or central corneal scars, corneal transplantation is indicated for advanced keratoconus. This can be performed as deep anterior lamellar keratoplasty (DALK) or as penetrating keratoplasty (PKP). The German keratoplasty registry shows that the proportion of anterior lamellar grafts in Germany has remained stable at approximately 5 % in recent years.

METHODS

Up to now DALK has not been technically standardized but can result in a good visual acuity using the big bubble technique if Descemet's membrane is laid bare intraoperatively. In 10-20 % a conversion to PKP is required if perforation of Descemet's membrane occurs. In cases of advanced keratoconus PKP is still the method of first choice especially after corneal hydrops due to rupture of Descemet's membrane. Non-contact excimer laser trephination seems to be especially beneficial for eyes with iatrogenic keratectasia after LASIK and those with repeat grafts in cases of keratoconus recurrence due to the graft being too small. For donor trephination from the epithelial side, an artificial chamber is used. Wound closure is achieved by a double running cross-stitch suture according to Hoffmann. Graft size is adapted individually depending on corneal size (as large as possible and as small as necessary). Limbal centration is given priority intraoperatively due to optical displacement of the pupil.

RESULTS

Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient centration, reduces vertical tilt and horizontal torsion of the graft in the recipient bed, thus resulting in significantly less all-sutures-out keratometric astigmatism (2.8 D versus 5.7 D), higher regularity of the topography (SRI 0.80 vs. 0.98) and better visual acuity (0.80 vs. 0.63) in contrast to the motor trephine. The stage of the disease does not influence functional outcome after excimer laser PKP.

CONCLUSIONS

In cases with optimal course DALK achieves the same visual outcome as mechanical PKP but the healthy endothelium can be preserved and endothelial immune reactions are prevented in keratoconus. In contrast to the undisputed clinical advantages of excimer laser keratoplasty with orientation teeth/notches in keratoconus, the major disadvantage of femtosecond laser application is still the necessity of suction and applanation of the cone during trephination.

Thirty years of cornea cultivation: long-term experience in a single eye bank

PURPOSE

To evaluate donor demographics, trends in donor tissue procurement and tissue storage over a long period.

METHODS

A retrospective, longitudinal, descriptive analysis was undertaken of data from the Hamburg Eye Bank Data Base (HEB-DB) that had been collected between 1981 and 2010. Data on 54 parameters of cornea donors [including clinical history, age, death cause, gender and death-to-explantation interval (DEI)] and of cultivated corneas (endothelial quality and development in culture, cultivation period, microbiological contamination) were retrieved. These data were analysed statistically, focusing on the historical development of the eye bank.

RESULTS

At the time of retrieval (June 2010), the HEB-DB contained data on 10 943 corneas (5503 donors). Most donors were men (65%) and had died from cardiopulmonary (n = 801)/cerebral (n = 261) failure or as the result of a polytraumatic accident/suicide (n = 602). Within these years, donor age, DEI and storage time increased. The percentage of stored corneas suitable for transplantation displayed a variable but increasing trend; in 2007, almost 75% of the stored corneas were transplanted. Between 1995 and June 2010, the median microbiological contamination rate was 5.3%. A change in the procurement procedure from enucleation to corneoscleral explantation in 2008 led to a briefly increased contamination rate.

CONCLUSION

  Donor demographic data run parallel to the general demographic development. Our analysis indicates a dynamic development of the eye bank over the last 30 years and emphasizes the need for an active quality management in coping with the challenges of modern eye banking.

[Visual acuity and astigmatism after keratoplasty. Differences between the guided trephine system and motor trephine]

BACKGROUND

The purpose of this study was to assess the differences in postoperative visual acuity, astigmatism, and selected postoperative complications between a guided trephine system (GTS) and motor trephine after penetrating keratoplasty.

PATIENTS AND METHODS

In this retrospective analysis 74 patients who had undergone penetrating keratoplasty either by GTS (n = 53) or by motor trephine (Motortrepan) (n = 21) were included. Both patient groups included in this analysis were selected to ensure a homogeneous distribution of preoperative parameters to the greatest possible extent. However, some significant differences in patient selection between the two groups could not be avoided. Patients in the motor trephine group were older (mean age 68.4 years vs 56.4 years; p < 0.01) and had Fuchs' endothelial dystrophy more often (47.6 % vs 26.4 %) and significantly less keratoconus (14.3 % vs 32.1 %).

RESULTS

No significant differences regarding visual acuity outcomes could be found between GTS and Motortrepan. In both patient groups there were no differences in the amount of preoperative astigmatism (1.36 vs. 2.0 dpt., p = 0.39). However, at the time of final corneal suture removal (2.23 vs. 3.5 dpt., p = 0.03) and at a postoperative control 1 year after final suture removal (2.29 vs. 3.85 dpt., p = 0.005) the amount of astigmatism in the motor trephine group was found to be significantly higher.

CONCLUSION

In summary penetrating kerastoplasty using the motor trephine was found to result in significantly higher postoperative astigmatism than those performed with the GTS.

Split cornea transplantation: relationship between storage time of split donor tissue and outcome. Ophthalmology. 2013;120:899-907. [PMID: 23399381 DOI: 10.1016/j.ophtha.2012.11.012]

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.

Results of excimer laser penetrating keratoplasty in aphakic eyes

BACKGROUND

Corneal grafting in aphakic eyes is often challenging. We report about the outcome of excimer laser trephination in aphakic eyes.

METHODS

We examined 17 eyes of 17 patients. Diagnosis in 11 eyes was endothelial decompensation and in six, corneal scars. We performed an excimer laser keratoplasty with intraoperative "Flieringa ring" suturing. Follow-up ranged between 3 and 41 (17.6 ± 11.7) months. Main outcome measures included: best-corrected visual acuity (BCVA), intraocular pressure (IOP), topographic astigmatism, corneal refractive power (CRP), central corneal thickness (CCT) and endothelial cell density (ECD).

RESULTS

Preoperative BCVA was light perception in two eyes, hand motion in seven, finger counting in one eye, under 20/400 in six eyes and 20/200 in one eye. IOP ranged between 4 and 28 (13.6 ± 5.1) mmHg. Topographic astigmatism ranged from 0.5 to 18.5 (7.0 ± 6.9) dioptres. CRP was between 38 and 59 (46 ± 9) dioptres. CCT was between 404 and 1069 (748 ± 181) μm. Postoperative BCVA was hand motion in five eyes, under 20/400 in two and ranged between 20/200 and 20/20 in ten eyes. IOP ranged between 10 and 40 (18.3 ± 8.5) mmHg. Topographic astigmatism ranged from 0.9 to 13 (5.5 ± 3.2) dioptres. CRP was between 31.9 and 46.7 (42 ± 4.1) dioptres. CCT was between 349 and 820 (552 ± 115.57) μm. ECD was between 592 and 2319 (1674 ± 553) cells/mm(2).

CONCLUSIONS

Excimer laser trephination can deliver beneficial visual outcomes in most of the aphakic eyes.

Improved wound stability of top-hat profiled femtosecond laser-assisted penetrating keratoplasty in vitro

PURPOSE

The femtosecond laser is a new option for cutting corneal tissue at high precision. The "top-hat" profile has an overlapping graft-host interface at the edge because of a larger inner trephination diameter. This may enhance graft fixation, thus improving the outcome and accelerating rehabilitation after penetrating keratoplasty.

METHODS

Femtosecond laser top-hat keratoplasties with overlaps of 0 and 3 mm between inner and outer trephination diameters were performed in vitro. After trephination, the excised corneal buttons were readapted by different suturing profiles. Pressure in the artificial anterior chamber was then raised until we observed wound leakage and ultimately wound prolapse.

RESULTS

Better wound stability was found in conjunction with all profiled trephinations. When using 4 interrupted sutures, wound leakage occurred at a median of 13.0 cm H2O (mean, 12.3 cm H2O) and "zero overlap," at 19.0 cm H2O (mean, 20.8 cm H2O) and 1-mm overlap, at 32.0 cm H2O (mean, 32.8 cm H2O) and 2-mm overlap, and at 48.5 cm H2O (mean, 49.4 cm H2O) and 3-mm overlap. Comparing zero overlap with the mean values of 1- to 3-mm overlaps, wound leakage happened at 13.0 (mean, 12.3) versus 32.0 (mean, 34.3) cm H2O with 4 interrupted sutures, at 57.5 (mean, 58.3) versus 61.0 (mean, 70.8) cm H2O with 8 interrupted sutures, at 31.5 (mean, 32.0) versus >97.0 (mean, 75.5) cm H2O with 1 running and 4 interrupted sutures, and at 34.0 (mean, 32.3) versus 80.0 (mean, 69.9) cm H2O with 1 running suture. The analysis of variance revealed a statistically significant increase in wound stability for all overlaps independently from the size of the overlap.

CONCLUSIONS

Femtosecond laser-assisted profiles with even small overlaps for penetrating keratoplasty may make fewer sutures and earlier suture removal possible because of better wound stability, contributing to earlier visual recovery and helping to prevent wound rupture after trauma. However, further study is required to identify the optimum profile including the various technical parameters.

Clinical results of 123 femtosecond laser-assisted penetrating keratoplasties

BACKGROUND

Postoperative astigmatism following penetrating keratoplasty is a major problem after corneal transplantation. The main goal of new trephination techniques such as femtosecond laser or excimer-laser trephination is to improve refractive and visual outcomes. The femtosecond laser technique makes profiled corneal trephinations such as the top hat or mushroom profile possible. We present the postoperative outcome of femtosecond laser-assisted penetrating keratoplasties.

METHODS

We performed 123 femtosecond laser-assisted penetrating keratoplasties in 119 patients. The main outcome measures were intraoperative specifics, astigmatism, and irregularity in Orbscan corneal topography, as well as the occurrence of immune reactions and side-effects.

RESULTS

All sutures have been removed in 49 of these 123 eyes. Their mean follow-up was 13.9 ± 4.5 months. Time to complete suture removal (n = 49) was 12.0 ± 3.7 months in the mushroom group and 9.8 ± 2.1 months in the top hat group. Mean astigmatism in Orbscan topography was 6.4 ± 3.0 diopters in the mushroom and 5.8 ± 4.6 diopters in the top hat group (all sutures out).

CONCLUSIONS

Femtosecond laser-assisted penetrating keratoplasty is a safe surgical technique. Due to the steps in profiled trephinations, the wound area is larger and theoretically the wound healing is, thus, faster and more stable. Complete suture removal is possible at an earlier time point compared to conventional penetrating keratoplasty. However, refractive results are not superior to those following conventional trephination.

[Perspectives of excimer laser-assisted keratoplasty]

BACKGROUND AND PURPOSE

The purpose of this paper is to demonstrate the evolution of laser keratoplasty and to outline the potential future perspectives of this technique.

METHODS

For non-contact donor trephination from the epithelial side an artificial anterior chamber has been used. Since 1989 more than 3,300 penetrating keratoplasty operations (PKP) have been performed successfully with the Zeiss-Meditec MEL60® excimer laser in Erlangen and Homburg/Saar.

RESULTS

Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient decentration, reduces vertical tilt and horizontal torsion of the graft in the recipient bed, thus resulting in significantly less all-sutures-out keratometric astigmatism, higher regularity of the topography and better visual acuity. Besides less blood-aqueous barrier breakdown during the early postoperative course after PKP, excimer laser trephination does not induce cataract formation and does not impair the graft endothelium. Likewise, the rate of immunological graft rejections is not adversely affected by the excimer laser. In addition, trephination of an instable cornea is facilitated.

CONCLUSIONS

Because of undisputed clinical advantages, especially in eyes with keratoconus, excimer laser trephination with orientation teeth/notches is still favored in Homburg/Saar in daily practice. The femtosecond laser (FSL)-assisted keratoplasty technique is very exciting but a prospective randomized study is required to determine potential benefits over excimer laser PKP.

Split cornea transplantation for 2 recipients - review of the first 100 consecutive patients

PURPOSE

To evaluate the feasibility of split cornea transplantation for 2 recipients by combining deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK).

DESIGN

Interventional case series.

METHODS

Fifty consecutive eyes with anterior stromal disease suitable for DALK and 50 eyes with endothelial disease suitable for DMEK were scheduled for split cornea transplantation combining both procedures within 72 hours. Main outcome measures included success of using a single donor cornea for 2 recipients, best spectacle-corrected visual acuity (BSCVA), and complication rates within 6 months' follow-up.

RESULTS

A single donor cornea could be used for 2 recipients in 47 cases (94%). In 3 eyes (6%), the DALK procedure had to be converted to penetrating keratoplasty (PK) requiring a full-thickness corneal graft. Thereby, 47 donor corneas (47%) could be saved. Six months after surgery, mean BSCVA was 20/36 in the 47 eyes that underwent successful DALK, 20/50 in the 3 eyes that underwent conversion from DALK to PK, and 20/29 in the 50 eyes that underwent DMEK. Postoperative complications after DALK included Descemet folds in 5 eyes (11%) and epitheliopathy in 3 eyes (6%). After DMEK, partial graft detachment occurred in 26 eyes (52%) and was managed successfully with intracameral air reinjection. All corneas remained clear up to 6 months after surgery. No intraocular infections occurred.

CONCLUSION

Split use of donor corneal tissue for combined DALK and DMEK procedures in 2 recipients within 3 subsequent days is a feasible approach to reduce donor shortage in corneal transplantation in the future.

The intrastromal corneal ring in penetrating keratoplasty-long-term results of a prospective randomized study

PURPOSE

Postoperative astigmatism after penetrating keratoplasty is a major problem in corneal transplantation. The purpose of this prospective randomized study was to evaluate the efficacy and safety of an intrastromal corneal ring after penetrating keratoplasty.

METHODS

Twenty patients were included, 10 of whom received an intracorneal ring (group 1) and 10 who did not (group 2, control group). Astigmatism in Orbscan corneal topography, occurrence of immune reactions, and occurrence of side effects were this study's main outcome criteria.

RESULTS

Mean follow-up time was 27.6 ± 5.3 months. Mean astigmatism (Orbscan) was 4.4 diopters in group 1 and 4.4 diopters in group 2 (P = 0.695). Spontaneous suture rupture occurred in 5 patients with corneal ring but in none of those in the control group. We observed 3 immune reactions in 3 patients with corneal ring, whereas group 2 experienced no rejection (P < 0.05). Endothelial cell loss was 15.1% in the group with the ring and 8.7% in the control group. That difference was not statistically significant (P = 0.146).

CONCLUSIONS

The use of the intrastromal corneal ring after penetrating keratoplasty caused no reduction in postoperative astigmatism. However, its use was statistically significantly associated with adverse events.

Split cornea transplantation for 2 recipients: a new strategy to reduce corneal tissue cost and shortage

PURPOSE

To evaluate the feasibility of using a single donor cornea for 2 recipients by combining deep anterior lamellar keratoplasty (DALK) and Descemet's membrane endothelial keratoplasty (DMEK) surgeries on the same day.

DESIGN

Single-center, nonrandomized, prospective, interventional case series.

PARTICIPANTS

Twelve consecutive donor corneas were scheduled for split cornea transplantation combining DALK for a keratoconus patient and DMEK for a Fuchs' endothelial dystrophy patient on the same surgery day.

METHODS

First, a big-bubble DALK procedure was performed for the keratoconus eye. When bare Descemet's membrane was prepared successfully requiring no conversion to penetrating keratoplasty (PK), then during surgery the donor, endothelium-Descemet's membrane layer was removed and stored for subsequent DMEK in a second patient, and the remaining anterior lamella of the donor cornea was used to complete the DALK surgery. Afterward, a DMEK procedure was performed on the second patient with Fuchs' endothelial dystrophy, grafting the stored endothelium-Descemet's membrane layer of the original donor button.

MAIN OUTCOME MEASURES

Success of using a single donor cornea for 2 recipient eyes, best spectacle-corrected visual acuity (BSCVA), and complication rates within 6 months follow-up.

RESULTS

A single donor cornea could be used for 2 recipients in 10 of 12 donor buttons (83%). In 2 cases (17%), the DALK procedure had to be converted to PK requiring a full-thickness corneal graft. Therefore, 10 donor corneas (45%) could be saved. Six months after surgery, mean BSCVA was 20/35 (range, 20/50-20/25) in 10 eyes that underwent successful DALK, 20/50 (range, 20/63-20/40) in 2 eyes that underwent conversion from DALK to PK, and 20/31 (range, 20/50-20/16) in 10 eyes that underwent DMEK. Postoperative complications after DALK included Descemet's folds in 3 eyes (30%) and epitheliopathy in 2 eyes (20%). After DMEK, partial graft detachment occurred in 5 eyes (50%) and was managed successfully with intracameral air reinjection. All corneas remained clear up to 6 months after surgery.

CONCLUSIONS

Split use of donor corneal tissue for combined DALK and DMEK procedures in 2 recipients on the same surgery day is a promising strategy to reduce donor shortage and cost in corneal transplantation surgery in the future.

[Keratoplasty: laminate or penetrate? Part 1: penetrating keratoplasty]

A number of corneal disorders sooner or later call for a decision as to whether corneal grafting is necessary. The problems of the current gold standard treatment, conventional penetrating keratoplasty (PKP), have yet to be fully solved, namely accelerated postoperative endothelial cell loss, endothelial immune reactions and the induction of astigmatism, which depends among other things on the trephination technique used. The use of a hand trephine may lead to different cutting angles between donor and recipient, resulting in increased postoperative astigmatism. This technique is therefore now only used for certain indications. One major advantage of mechanically guided trephine systems, which are now considered standard, is the possibility of trephining the donor disc from the epithelial side to avoid donor oversizing, therefore reducing postoperative astigmatism. Even less astigmatism is induced in keratoconus patients using an Excimer laser for trephination, as this technique does not lead to corneal deformation during trephination. Furthermore, this non-contact method can also be used to trephine unstable corneas. Femtosecond lasers allow the creation not only of straight but also profiled trephination edges, leading to more stable wound healing and hence earlier suture removal.

[Penetrating keratoplasty with intrastromal corneal ring. A prospective randomized study]

BACKGROUND

The purpose of the study was to evaluate the efficacy and safety of Krumeichs' intrastromal corneal ring following penetrating keratoplasty. Postoperative astigmatism and occurrence of complications were the main criteria of this study.

MATERIAL AND METHODS

A total of 20 patients were included in this prospectively randomized study (10 patients with and 10 patients without corneal ring). Follow-up examinations were performed 6 weeks, 4, 12, and 18 months postoperatively, including best corrected visual acuity and Orbscan corneal topography.

RESULTS

The mean follow-up time is currently 18.9+/-2.8 months. The mean astigmatism (Orbscan) is 3.9 D in the group with ring and 4.0 D in the group without a ring. Spontaneous suture rupture occurred in five patients with corneal ring.

CONCLUSIONS

The use of the intrastromal corneal ring following penetrating keratoplasty caused no reduction of postoperative astigmatism. The reason for the spontaneous suture ruptures is unclear.

[Application of wavefront analysis in clinical and scientific settings. From irregular astigmatism to aberrations of a higher order--Part II: examples]

In recent years, wavefront analysis has ceased to be purely a laboratory application and emerged as a method used in ophthalmological diagnosis. This development has been promoted mainly by the widespread use of wavefront-guided LASIK (laser in situ keratomileusis). However, aberrometry is still not a common diagnostic technique, and for many ophthalmologists interpretation of the results is difficult. The second part of this serial paper reviews findings that are relevant for the ophthalmological community and highlights current scientific applications in this area.

[Satisfaction with penetrating keratoplasty. Results of a questionnaire census]

BACKGROUND

Penetrating keratoplasty (PKP) is commonly referred to as the most successful transplantation procedure in medicine. This appraisal, however, is currently poorly supported by evidence. The aim of our study was to collect data on patient satisfaction with PKP as well as to analyze factors predisposing to dissatisfaction.

PATIENTS AND METHODS

In the years 1988-2002 a total of 3,219 PKPs were performed on 2,981 patients. These patients were sent a questionnaire. The items pertained to subjective assessment of visual quality as compared to the situation before PKP and about regretting the PKP.

RESULTS

The questionnaire was answered by 1,142 patients (59% of the traceable persons). The mean follow-up was 3.3+/-2.9 years. Indications for PKP were Fuchs' endothelial dystrophy (26%), keratoconus (23%), bullous keratopathy (15%), and further indications (36%). For these groups, best corrected visual acuity improved by more than two lines in 51, 80, 42, and 50%, respectively. The percentage of subjective improvement of vision was 73, 78, 47, and 63%. The percentage of regretting the PKP was 12, 4, 27, and 10%, respectively. All differences were highly statistically significant. Significant influencing factors on regretting the PKP were (inversely sorted for relevance): repeat graft failure, bullous keratopathy, contact lens wear, paresthesia, removal of running sutures, and patient age.

CONCLUSIONS

General satisfaction with PKP is high. An important exception is bullous keratopathy, most likely due to accompanying morbidity (e.g., cystoid macular edema).

Corneal Trephination With the Femtosecond Laser

PURPOSE

To evaluate the feasibility and cut quality of corneal trephination in human donor corneal tissue with the femtosecond laser.

METHODS

Twelve human corneoscleral discs were inserted in an artificial anterior chamber. After corneal thickness measurement and tonometry, the cornea was mounted on a femtosecond laser (FEMTEC; 20/10 Perfect Vision, Heidelberg, Germany) through a contact lens (patient interface). Trephination was performed with diameters of 7.0, 7.5, 8.0, and 8.5 mm in 3 corneas each. The corneal button was removed from the corneoscleral disc in 2 of the 3 corneas in each case. The cut was not manipulated in the remaining corneas to enable histologic detection of possible tissue bridges. The cut edges were macroscopically and light-microscopically examined for quality.

RESULTS

Corneal buttons and corneoscleral discs could be separated by blunt dissection in all cases. Tissue bridges were more common in thicker edematous corneas than in thinner ones. Both the macro- and microscopic examination disclosed smooth rectilinear cut margins with a perpendicular cut edge.

CONCLUSION

This feasibility study shows that the femtosecond laser enables sufficient trephination of human donor corneas.