Prophylaxe und Management von Komplikationen bei perforierender Keratoplastik

Simultaneous Muraine Sutures and Excimer Laser-Assisted Penetrating Keratoplasty for Acute Keratoconus

Background: Acute keratoconus (acute KC), which affects approximately 1.6-2.8% of keratoconus (KC) patients, is a pathological condition of the cornea characterized by stromal edema due to entry of aqueous humor through a tear in Descemet's membrane. Methods: We present a novel combination of surgical procedures that allows swifter visual recovery in a consecutive, retrospective case series. The new surgical procedure for acute KC consists of a combination of Muraine corneal sutures to smooth the corneal curvature and Excimer laser-assisted penetrating keratoplasty and was performed in six acute KC patients from 2019 to 2022 at the Department of Ophthalmology, University Hospital of Martin-Luther-University Halle-Wittenberg (UMH), Germany. We monitored data on preoperative status, operative details, intraoperative and postoperative complications and visual outcomes were analyzed. Results: The mean age was 41.5 ± 13.5 years (3 OD, 3 OS). Neurodermatitis was present in 3 patients (50%). All patients received significant visual benefits from the procedure. Preoperative BCVA was hand motion (logMAR 3.0) in all patients; postoperatively, BCVA improved significantly logMAR 0.03 ± 0.09 [range: 0.2-0.4; p < 0.001, FUP 20+/-10 months). Visual acuity remained stable throughout the roughly biannual follow-ups. One patient developed endothelial graft rejection after 2 years. During the last examination, all eyes had clear grafts and stable curvatures, K1 and K2 being 42.43 ± 4.17 D and 44.95 ± 4.07 D, respectively, and mean corneal astigmatism was 2.61 ± 1.74 D. The thinnest corneal thickness was 519 ± 31 µm. A graft size of 8.0 × 8.1 mm was the most beneficial. Conclusions: in patients with acute KC and hydrops, a penetrating keratoplasty with Muraine corneal sutures is successful in terms of graft clarity and visual outcome. Combining the procedures allows quicker visual recovery. Patients with a history of neurodermatitis should have preoperative and postoperative dermatologic treatment and close follow-up for possible complications.

[Keratoplasty - an Overview of the Methods and their Perioperative Management]

Corneal transplantation can be divided into two groups: penetrating and lamellar keratoplasty. Newer minimally invasive procedures have emerged over the years, to improve the visual outcome and reduce complications. This article summarizes the different procedures, their indications and complications, and outlines the pre-, peri- and postoperative management in a clinical setting.Corneal transplantation is the most commonly performed transplantation of donor tissue in modern medicine. In the last years a shift away from penetrating keratoplasty (PK) towards minimally invasive lamellar operative techniques, associated with less complications, can be observed. The Descemet membrane endothelial keratoplasty (DMEK) is used to treat endothelial corneal pathologies and has overtaken the PK to become the most commonly performed form of keratoplasty. Preparation and identification of possible risk-factors are essential preoperative steps to reduce peri- and postoperative complications of keratoplasties. If corneal graft rejection occurs, early and maximum therapy is crucial for graft survival. Laser-assisted techniques offer different advantages in lamellar and penetrating keratoplasty but are not very cost-efficient.

Graft Failure after PKP and DMEK: What is the Best Option?

Corneal transplantation is the most commonly performed human tissue transplantation procedure worldwide. Due to the large number of grafts, corneal graft failure has become one of the most common indications for corneal transplantation for immunological and non-immunological reasons (e.g. recurrence of underlying disease, high intraocular pressure, grafted guttae, transmitted HSV or CMV infection). The relatively recently developed lamellar grafting techniques have introduced certain potential complications that may lead to graft failure and require approaches other than penetrating keratoplasty for re-grafting. On the other hand, these new lamellar techniques also offer new possibilities for salvaging failed penetrating grafts, with potential advantages over successive penetrating keratoplasties, such as lower intraoperative risks, faster visual rehabilitation and reduced risk of immune reaction. Today, the patient with good healing who is satisfied with his graft before endothelial decompensation, with low astigmatism and no stromal scars, represents the optimal condition for DMEK after PKP. This can also be combined with phacoemulsification (so-called triple DMEK). Otherwise, a penetrating re-keratoplasty with a larger graft (typically excimer laser repeat PKP 8.5/8.6 mm) is performed to treat edema, scars and irregular astigmatism simultaneously. The medical history carries weight in this decision! Re-DMEK in case of graft failure after DMEK and DSAEK does not require any modification of the standard technique and leads to good visual acuity results if performed quickly. If there is clear stromal scarring after multiple (external) DMEKs, PKP can also be considered to rectify the situation. Otherwise causeless recurrent graft failures must suggest herpetic or CMV endotheliitis and, after PCR analysis of the aqueous humour aspirate, be treated appropriately with medication.

[Optical rehabilitation and pediatric ophthalmological care following keratoplasty for childhood corneal opacities]

BACKGROUND

The younger the children are at the time of corneal transplantation, the worse the survival prognosis of the graft.

PREOPERATIVE CONSIDERATIONS

Preoperative considerations are significant in terms of accurate parental education, ensuring adherence to treatment and choosing the appropriate surgical time frame (amblyopia versus graft failure, compliance of the patient). Parental education must include the reduced visual prognosis in young children, exceptions being later acquired corneal pathologies such as inflammatory corneal scars (herpes) and keratoconus.

POSTOPERATIVE CARE

A distinction must be made between morphological care after transplantation and refractive correction as well as treatment of amblyopia. The younger the children, the less favorable the prognosis for the transplant and the more often multiple examinations with anesthesia are necessary in order to detect complications, such as infiltrates or suture loosening at an early stage. Especially unilateral congenital pathologies often do not lead to a sufficient improvement of amblyopia (refractory amblyopia, poor compliance).

CONCLUSION

The prognosis after keratoplasty in childhood is already partly decided by the careful evaluation of indications (no surgery of a sclerocornea) and the detailed and realistic clarification for the parents (cooperation with long-term ocular and systemic treatment even if the child has poor compliance, frequent check-ups, reduced chances of amblyopia treatment). The younger the child is at the time of transplantation, the more frequent are graft failure and the development of complications. Later manifesting diseases in older children (herpetic corneal scars, keratoconus) have a better prognosis.

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.

[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.

Semiquantitative Criteria in the Eye Bank That Correlate with Cornea Guttata in Donor Corneas

BACKGROUND

Cornea guttata may not be recognized in the eye bank and recent studies have displayed that guttae are transplanted in about 15% of cases in varying severities. The purpose of this study was to establish semiquantitative criteria for the detection of cornea guttata in donor corneas in the eye bank.

METHODS

In this retrospective cohort study, preoperative endothelial pictures of donor corneas were collected and classified according to the post-penetrating keratoplasty cornea guttata grade into three distinct groups: group 1 consists of healthy corneas with no guttae (guttata grade 0); group 2 constitutes corneas with mild asymptomatic cornea guttata (guttata grade +); and group 3 comprises corneas with advanced widespread cornea guttata (guttata grade ++/+++/++++). The preoperative pictures of each group were then individually analyzed using the following five semiquantitative criteria: The number and the area of the cell-depleted surfaces, the presence of less than 50% of the cells having a hexagonal or a circular shape, the presence of cell membrane defects and interruptions, the presence of blebs in the cell membrane, and the presence of groups of cells with a distinct whitish color.

RESULTS

In total, 262 patients were included in this study, with a total number of 1582 preoperative donor corneal endothelial pictures. Out of those pictures, groups 1, 2, and 3 encompassed 995 (62.9%), 411 (26.0%), and 176 (11.1%) pictures, respectively. Three out of the five eye bank criteria were found to correlate with postoperative cornea guttata with a highly significant p value of < 0.001. These three criteria are the presence of less than 50% of the cells having a hexagonal or a circular shape, the presence of cell membrane defects and interruptions and, the presence of blebs. The presence of groups of cells with a distinct whitish color was only a weak predictive factor for cornea guttata (p = 0.069). There was no statistically significant correlation between the number and the area of cell-depleted surfaces and postoperative cornea guttata with a p = 0.181.

CONCLUSION

Three semiquantitative criteria that can be detected in the eye bank using inverted light microscopy seem to correlate with postoperative cornea guttata: The presence of blebs, the presence of cell membrane defects and interruptions, as well as endothelial pictures with less than 50% of the cells having a hexagonal of circular shape. The presence of groups of cells with a distinct whitish color appears to be a weak predictor of cornea guttata.

[Descemet membrane endothelial keratoplasty DMEK - Donor and recipient step by step]

In 2020 Descemet membrane endothelial keratoplasty (DMEK) has become the gold standard in Germany for the treatment of corneal endothelial diseases; however, the widespread use of DMEK was initially limited due to problems with donor preparation and the difficulty of correctly and gently unfolding the endothelial Descemet membrane (EDM) in the anterior chamber. Following the situational donor selection, the safe single-handed donor preparation of the cornea without tearing or even rupturing the EDM, including the indispensable peripheral semicircular orientation marking. Also presented is a step by step atraumatic loading of the glass cartridge, the introduction of the EDM roll into the anterior chamber, and its safe step by step unfolding based on (1) the sequential use of jets of fluid, (2) repeated tapping on the peripheral/central cornea, (3) controlled flattening of the anterior chamber, (4) use of air bubbles of defined size and finally, the fixation of the EDM in correct orientation to the back of the host cornea with a gas bubble. Since every wrong step with DMEK can have far-reaching consequences for patient and surgeon, this step by step pragmatic approach should minimize the incidence of donor tissue damage and failure in patient maneuvers.

Clinical and surgical factors and intraoperative complications in patients who underwent penetrating keratoplasty

Objective

to identify the main intraoperative complications of patients who underwent keratoplasty and relationship between these complications and clinical and surgical factors.

Method

cross-sectional observational study. A census of the patients submitted to keratoplasty was carried out, which totaled 258 procedures.

Results

twenty-two intraoperative complications were recorded, all in penetrating keratoplasty surgeries, of which 59.09% were performed in male patients with a mean age of 58.5 years. The main intraoperative complication was vitreous loss (36.36%). A statistically significant relationship was found between the variable “intraoperative complication” and the variables “previous surgery”, “combined keratoplasty and cataract extraction” and “corneal host button greater than 8.0 mm”.

Conclusion

identifying the main intraoperative complications of keratoplasty enables nurses to understand which factors may interfere with these procedures, point out possible predictors of complications, and seek control measures so that such complications do not occur.

Muscle Relaxants as a Risk Factor for Vis-à-tergo During Penetrating Keratoplasty: A Prospective Interventional Study

INTRODUCTION

This study aimed to investigate the influence of three muscle relaxants on intraocular pressure (IOP), ocular pulse amplitude (OPA), and vis-à-tergo (VAT) in patients undergoing penetrating keratoplasty (PKP) under general anesthesia.

METHODS

Ninety-five patients undergoing PKP were included in this prospective single-center interventional study. IOP and OPA were measured with a dynamic contour tonometer before and 5 min after onset of general anesthesia. Mivacurium (n = 30), atracurium (n = 35), and rocuronium (n = 30) were administered as nondepolarizing muscle relaxants. VAT was assessed 15 min after surgery had begun.

RESULTS

When mivacurium was used, IOP decreased by 2.2 mmHg [standard deviation (SD) ±2.2 mmHg; p < 0.001]. Atracurium decreased the IOP by an average of 5.8 mmHg (SD ±1.8 mmHg; p < 0.001) and rocuronium caused an IOP reduction of 7.2 mmHg (SD ±2 mmHg; p < 0.001). The relative IOP decrease was 12% with mivacurium, 29% with atracurium, and 37% with rocuronium (p < 0.001). OPA decreased by 0.6 mmHg with mivacurium (SD ±0.6 mmHg; 26%; p < 0.001), 1.3 mmHg with atracurium (SD ±1.3 mmHg; 40%; p < 0.001), and 1.2 mmHg with rocuronium (SD ±0.7 mmHg; 42%; p < 0.001). The relative OPA decrease was 26% with mivacurium, 40% with atracurium, and 42% with rocuronium (p < 0.001). VAT occurred in 36% of cases. Mivacurium was used in 77% of these cases, atracurium in 26%, and rocuronium in 6.6% (p < 0.001).

CONCLUSIONS

Mivacurium is associated with a higher risk of VAT during PKP. Therefore, atracurium or rocuronium may minimize complications in ocular surgery with large incisions.

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.

[Bilateral vascularized disciform corneal scar of herpetic origin in a child]

BACKGROUND

Bilateral keratitis is rare and can have various causes. For a good outcome after treatment, the correct diagnosis is decisive.

CASE REPORT

A 15-year-old boy presented to our clinic with recurrent keratoconjunctivitis and progressive loss of vision in both eyes since 6 years. The best corrected visual acuity was 0.1 in the right eye and 1/12 in the left eye. Slit-lamp examination verified keratitis disciformis with strongly vascularized corneal stromal scars without conjunctival follicles on both sides. Based on the clinical diagnosis, antiviral treatment was initiated. Best corrected visual acuity 8 weeks later increased to 0.4 in the right eye and 0.8 in the left eye and the corneal edema decreased in both eyes. Due to noncompliance the patient returned with a perforated corneal ulcer of the left eye, where an á chaud penetrating keratoplasty had to be performed.

RESULTS

Herpes simplex virus is one of the most common causes of keratitis and has different manifestations. In the treatment of keratitis disciformis the use of topical steroids is mandatory as there is an active immunological process. The use of systemic and local antiviral treatment is necessary at the same time in order to avoid reactivation of viral replication. Bilateral keratitis is relatively frequent in children.

CONCLUSION

Herpetic keratitis is now well treatable if the various manifestations of the disease are recognized early and an appropriate therapy is adjusted accordingly.

[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.