Outcomes of Descemet's membrane endothelial keratoplasty for congenital hereditary endothelial dystrophy

Updates on congenital hereditary endothelial dystrophy

Congenital hereditary endothelial dystrophy (CHED) is a rare genetic corneal disorder causing progressive cornea clouding and significant visual impairment. CHED remains a leading indication for pediatric corneal transplantation despite its infrequency, particularly in regions with high consanguinity rates like Southeast Asia. Identifying the Solute Carrier Family 4 Member 11 (SLC4A11) gene as the genetic basis of CHED has led to the discovery of it's various genetic variations. However, a comprehensive understanding of its clinical-genetic correlation, pathophysiology, and optimal management is ongoing. This review aims to consolidate current knowledge about CHED, covering its genetic origins, pathophysiological mechanisms, clinical presentation, and management strategies. Surgical intervention, such as penetrating keratoplasty (PK), Descemet stripping automated endothelial keratoplasty (DSAEK), and Descemet membrane endothelial keratoplasty (DMEK), remains the primary treatment. DSAEK and DMEK offer advantages over PK, including quicker visual recovery, reduced complications, and longer graft survival, especially in the pediatric age group. The timing of surgical interventions depends on disease severity, age at presentation, comorbidities, and visual potential. Elevated oxidative stress in CHED corneal tissue suggests potential benefits from anti-inflammatory drugs to rescue mutated endothelial cells. Considering the limitations of corneal graft surgeries, exploring novel gene-based molecular therapies are essential for future management. Early diagnosis, appropriate surgical interventions, amblyopia control, and genetic counseling for predictive analysis are pivotal for optimizing CHED management. A multidisciplinary approach involving ophthalmologists, researchers, and genetic counselors is essential for precise diagnosis and optimal care for CHED patients.

Novel Proposed Algorithm in Congenital Hereditary Endothelial Dystrophy

PURPOSE

Congenital hereditary endothelial dystrophy (CHED) is a rare, autosomal recessive, monogenic corneal condition with variable expressivity. Often presents in bilateral symmetrical progressive corneal cloudiness that starts in the early infancy. It is characterized by increased corneal thickness, profound corneal edema, and thickening of the Descemet membrane due to endothelial dysfunction. The published literature lacks uniform guidelines for grading corneal cloudiness and management algorithm for CHED cases. This article focuses on applying newer investigational modalities to fine-tune surgical outcomes and more recent CHED management strategies.

METHODS

This comprehensive literature review was performed based on a search on the PubMed database of relevant CHED articles focusing on those published in the last 7 years. A total of around 70 articles were reviewed, and 17 of them were included in this review. These include systemic reviews, randomized controlled clinical trials, cohort studies, case-controlled studies, and case series.

RESULTS

Corneal cloudiness grading in CHED using subjective and objective methods using Anterior Segment Optical Coherence Tomography (AS-OCT) and densitometry using Scheimpflug imaging can help select appropriate management plan for CHED cases. DSAEK outscores penetrating keratoplasty with much fewer complications and expedites visual recovery, which helps mitigate amblyopia.

CONCLUSION

Managing cases of CHED has been a challenge due to the dilemma in timing and appropriate surgical method selection and lack of definitive medical or other conservative approaches. Currently, DSAEK has shown favorable results in cases of CHED. However, appropriate staging of CHED and selecting the appropriate management approach appears to play a critical role in managing such cases. Besides these, novel treatment modalities such as nonsteroidal anti-inflammatory agents (NSAIDS) that target restoring water-flux activity in subtype of CHED and gene editing using CRISPR-Cas9 are promising paradigm treatment modalities.

A review of techniques and outcomes of endothelial keratoplasty in congenital hereditary endothelial dystrophy

Congenital hereditary endothelial dystrophy affects the Descemet membrane and endothelium, resulting in corneal decompensation. Penetrating keratoplasty (PKP) has been the gold-standard surgical management until recently; however, at present, endothelial keratoplasty (DSEK/DSAEK/n-DSEK: Descemet-stripping or non-Descemet stripping endothelial keratoplasty and DMEK/n-DMEK: Descemet membrane endothelial keratoplasty) is being preferred due to lesser intraoperative and postoperative complications, early visual recovery, and comparable visual outcomes. Endothelial keratoplasty (EK) can be challenging, especially in pediatric eyes with CHED due to smaller eyeballs, shallow anterior chambers, phakic status, and poor intraoperative visibility due to thick and hazy corneas. A total of 198 articles matched our search strategy. After screening for duplication and going through the titles and abstracts, 12 relevant original articles, one case series, and six case reports were included in this review. Various surgical modifications have to be adopted in comparison to adult eyes to overcome the aforementioned difficulties. Regardless, studies have shown favorable visual outcomes with better graft survival and fewer complications in eyes that underwent EK compared to PKP. Hence, timely surgical intervention and strict amblyopia management can result in better final visual outcomes. The purpose of this review is to summarize various intraoperative difficulties and the surgical modifications required, different surgical techniques, visual and graft-related outcomes, and various complications of EK in CHED eyes.

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.

Microscope Integrated Optical Coherence Tomography Guided Descemet Stripping Automated Endothelial Keratoplasty in Congenital Hereditary Endothelial Dystrophy

Purpose

To describe the outcomes of descemet stripping automated endothelial keratoplasty (DSAEK) in congenital hereditary endothelial dystrophy (CHED) and to evaluate the role of microscope integrated optical coherence tomography (Mi-OCT) during the surgery.

Design

Retrospective data analysis.

Methods

A retrospective study from the medical records of all those patients who were diagnosed with CHED and underwent DSAEK at our centre from 2015 were evaluated. All patients underwent Mi-OCT-guided standard DSAEK procedure. Intra-operative difficulties, visual outcomes and graft survival were recorded.

Results

A total of 48 eyes of 29 patients with a mean age of 9.87 ± 8.2 years and mean follow-up of 17.3 months were evaluated. Thirty-nine eyes underwent primary DSAEK and 9 eyes underwent PKP. Three eyes who underwent PKP had failed graft for which they underwent DSAEK. The mean preoperative Snellen's visual acuity was 1.71 ± 0.66 and the mean preoperative central corneal thickness was 1.10 ± 0.174 mm. Intraoperatively, all the grafts were attached which was confirmed using Mi-OCT. Graft detachment was seen in the immediate postoperative period in 10.4% (4 eyes) of primary DSAEK, out of which DM scoring was not performed in 2 eyes. Following DSAEK, cornea cleared at four-week follow-up in 89.7% eyes and in all the eyes the cornea cleared at six-week follow-up.

Conclusion

Primary DSAEK could be a preferred option over PKP for CHED with early presentation and in those eyes with failed primary PKP. Mi-OCT is a very useful tool in these eyes for various intraoperative procedures, thereby improving the outcomes of the procedure.