Graft failure: II. Ocular surface complications

Long-term outcomes following primary versus secondary Boston keratoprosthesis type 1 implantation

BACKGROUND/AIMS

To compare long-term outcomes of primary versus secondary (postgraft failure) Boston keratoprosthesis type 1 (KPro) implantation.

METHODS

Medical records of patients at the Centre hospitalier de l'Université de Montréal having undergone KPro implantation between 2008 and 2017 were reviewed and included if they had a preoperative Snellen best-corrected visual acuity (BCVA) of 20/100 or worse and a minimum of 5 years of follow-up. Eighty-two eyes were separated into two cohorts (40 primary, 42 secondary KPro) and BCVA, complications and device retention were evaluated between groups.

RESULTS

BCVA improved from baseline in both groups at each year; this was significant at all five postoperative years in the primary group and the first 3 years in the secondary group (p<0.05). Mean BCVA was similar between groups at 5 years (logarithm of minimal angle resolution 1.3±0.8 in the primary group vs 1.5±0.8 p<0.05). Idiopathic vitritis, choroidal detachment and new glaucoma occurred more after primary KPro (n=7, 17.5% vs n=1, 2.4%; n=11, 27.5% vs n=3, 7.14% and n=14, 35% vs n=6, 14%, respectively; p<0.05). Primary KPro had lower retention (n=28, 70% vs n=38, 91%, p<0.05) at final follow-up. There was more aniridia in the primary group (n=19, 48% vs n=6, 14%, p<0.01). Within each group, 50% of removals occurred in aniridic eyes.

CONCLUSION

Primary KPro yielded favourable long-term visual outcomes but had more complications and lower retention rates than secondary KPro, likely explained by preoperative indications. Primary device implantation represents a favourable option for patients for whom grafts are likely to fail.

Corneal neovascularization

The optical clarity of the cornea is essential for maintaining good visual acuity. Corneal neovascularization, which is a major cause of vision loss worldwide, leads to corneal opacification and often contributes to a cycle of chronic inflammation. While numerous factors prevent angiogenesis within the cornea, infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation can all disrupt these homeostatic safeguards to promote neovascularization. Here, we summarize its etiopathogenesis and discuss the molecular biology of angiogenesis within the cornea. We then review the clinical assessment and diagnostic evaluation of corneal neovascularization. Finally, we describe current and emerging therapies.

Cataract Surgery in Dry Eye Disease: Visual Outcomes and Complications

Purpose: To describe the visual outcomes and complications following cataract surgery in dry eye disease (DED). Methods: This retrospective study included 668 eyes of 399 patients with DED, who underwent cataract surgery between 2011 and 2019 at our multi-tier ophthalmology hospital network. Based on etiology, they were divided into three groups: cicatrizing conjunctivitis (CC), meibomian gland dysfunction (MGD), and Sjogren's syndrome (SS). The data on demographics, visual impairment, surgical technique, visual outcomes, and complications were collected using an electronic medical record system. Median LogMAR best corrected visual acuity (BCVA) with interquartile range (IQR) was compared using Wilcoxon's rank sum test. Results: The median age at which cataract surgery was performed was 58 (IQR: 47-65) years. Etiology of DED was CC in 279, MGD in 255, and SS in 134 eyes. Most (471) eyes underwent phacoemulsification, under peribulbar anesthesia (548) through a temporal clear corneal incision (209) with foldable intraocular lens implantation (417). The overall median LogMAR BCVA improved from 1.1 (IQR: 0.6-2.1) at baseline to 0.3 (IQR: 0.1-0.7) and 0.1 (IQR: 0-0.65) at 1 and 6 weeks (p < 0.0001) post-operatively. The median 6 weeks post-operative BCVA was 0.3, 0.1, and 0.1 in CC, MGD, and SS, respectively, and significantly better than at baseline (p < 0.0001). The leading cause of sub-optimal vision was corneal scarring (44; 9%), and the most common complication was posterior capsular rupture with vitreous loss (23; 3%). Conclusion: Cataract surgery has good visual outcomes in patients with DED, without any disconcerting rate of complications. Pre-existing keratopathy is the main determinant of the extent of post-operative visual recovery.

Simultaneous penetrating keratoplasty and amniotic membrane transplantation in eyes with a history of limbal stem cell deficiency

PURPOSE

To describe the outcomes of simultaneous penetrating keratoplasty (PK) and amniotic membrane transplantation (AMT) performed both as a ring-shaped graft and as a temporary patch in eyes with a history of limbal stem cell deficiency (LSCD).

METHODS

Prospective observational case series including 48 simultaneous PK/AMT procedures (48 patients) in eyes with a history of partial or total LSCD. Patients with total LSCD were first treated with limbal stem cell transplantation. The preoperative indication was graft failure in 58.3% of cases. Most recipients (89.6%) were at high-risk for rejection.

RESULTS

The mean graft reepithelialization time was 29.2±30.8 days. Graft reepithelialization was achieved in 30 days in 70.8% of cases. No AMT-related adverse events were observed. The mean time from keratoplasty-to-last visit was 84.5±54.5 months. The 3-year graft survival rate was 62.5%. Recurrence of corneal epithelial defects after graft reepithelialization (47.9%) was associated with lower graft survival (P=0.004). In eyes with successful grafts at the last visit, the mean LogMAR visual acuity was 1.90 (20/1575)±5 lines before keratoplasty and 0.89 (20/155)±10 lines at 5 years. A ring of amniotic membrane was visible between the graft stroma and the corneal epithelium on slit-lamp examination and optical coherence tomography in all successful cases.

CONCLUSIONS

In this series of eyes with a history of LSCD and at high-risk of rejection, simultaneous PK and AMT were associated with satisfactory graft survival and no additional adverse events.

TFOS DEWS II iatrogenic report

Dry eye can be caused by a variety of iatrogenic interventions. The increasing number of patients looking for eye care or cosmetic procedures involving the eyes, together with a better understanding of the pathophysiological mechanisms of dry eye disease (DED), have led to the need for a specific report about iatrogenic dry eye within the TFOS DEWS II. Topical medications can cause DED due to their allergic, toxic and immuno-inflammatory effects on the ocular surface. Preservatives, such as benzalkonium chloride, may further aggravate DED. A variety of systemic drugs can also induce DED secondary to multiple mechanisms. Moreover, the use of contact lens induces or is associated with DED. However, one of the most emblematic situations is DED caused by surgical procedures such as corneal refractive surgery as in laser-assisted in situ keratomileusis (LASIK) and keratoplasty due to mechanisms intrinsic to the procedure (i.e. corneal nerve cutting) or even by the use of postoperative topical drugs. Cataract surgery, lid surgeries, botulinum toxin application and cosmetic procedures are also considered risk factors to iatrogenic DED, which can cause patient dissatisfaction, visual disturbance and poor surgical outcomes. This report also presents future directions to address iatrogenic DED, including the need for more in-depth epidemiological studies about the risk factors, development of less toxic medications and preservatives, as well as new techniques for less invasive eye surgeries. Novel research into detection of early dry eye prior to surgeries, efforts to establish appropriate therapeutics and a greater attempt to regulate and oversee medications, preservatives and procedures should be considered.

The Emerging Role of Nanotechnology in Cell and Organ Transplantation

Transplantation is often the only choice many patients have when suffering from end-stage organ failure. Although the quality of life improves after transplantation, challenges, such as organ shortages, necessary immunosuppression with associated complications, and chronic graft rejection, limit its wide clinical application. Nanotechnology has emerged in the past 2 decades as a field with the potential to satisfy clinical needs in the area of targeted and sustained drug delivery, noninvasive imaging, and tissue engineering. In this article, we provide an overview of popular nanotechnologies and a summary of the current and potential uses of nanotechnology in cell and organ transplantation.

Primary implantation of type I Boston keratoprosthesis in nonautoimmune corneal diseases

PURPOSE

The aim of this study was to report outcomes of type I Boston keratoprosthesis (KPro) as primary corneal surgery in nonautoimmune corneal disorders.

METHODS

In this retrospective, observational, large single-center case series of 43 eyes (37 patients) that were followed for an average of 39 months (1-6 years), primary implantation of the type I Boston KPro was performed in all patients. Visual acuity at year 1, visual acuity at last follow-up, and postoperative complication rates were examined for all eyes.

RESULTS

Preoperative best-corrected visual acuity ranged from 20/60 to light perception, with vision of 20/200 or worse in 88%. Vision was ≥20/200 at 1 year in 77% of eyes (P < 0.0001). Complications included retroprosthetic membrane formation (51%), glaucoma progression (47%), corneal melt (19%), and sterile vitritis (14%).

CONCLUSIONS

In a large series with long follow-up, primary Boston KPro effectively restored vision. Close follow-up is needed to manage the known complications after Boston KPro.

Boston type 1 keratoprosthesis for chemical and thermal injury

PURPOSE

To evaluate the outcome of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed interventions for chemical and thermal injury.

METHODS

A retrospective review was performed of every eye with chemical or thermal injury that was treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications.

RESULTS

Nine eyes met the inclusion criteria, including 7 eyes with alkali burns, 1 eye with an acid burn, and 1 eye with a thermal burn. After a mean follow-up of 40.7 months (range, 29-60 months), the median best-corrected visual acuity was 20/60 (range, 20/15 to no light perception). One eye was ≥20/20, 3 eyes were ≥20/40, and 6 eyes were ≥20/70. The initial Kpro-1 prosthesis was retained in 7 (77.7%) eyes and successfully replaced in the other 2 eyes. One or more serious complications occurred in 6 (66.7%) eyes. These included 2 cases of sterile corneal ulceration with prosthesis extrusion, 2 cases of microbial keratitis (1 bacterial and 1 fungal), 2 cases of bacterial endophthalmitis, and 2 cases of retinal detachments. These complications contributed to visual outcomes of hand motions in 2 eyes and no light perception in 1 eye.

CONCLUSIONS

The Boston Kpro-1 is associated with highly satisfactory visual outcomes and prosthesis retention in most cases of severe chemical or thermal injury. Serious complications are common and may compromise the final outcome.

Corticosteroid-loaded biodegradable nanoparticles for prevention of corneal allograft rejection in rats

Immunologic graft rejection is one of the main causes of short and long-term graft failure in corneal transplantation. Steroids are the most commonly used immunosuppressive agents for postoperative management and prevention of corneal graft rejection. However, steroids delivered in eye drops are rapidly cleared from the surface of the eye, so the required frequency of dosing for corneal graft rejection management can be as high as once every 2h. Additionally, these eye drops are often prescribed for daily use for 1 year or longer, which can result in poor patient compliance and steroid-related side effects. Here, we report a biodegradable nanoparticle system composed of Generally Regarded as Safe (GRAS) materials that can provide sustained release of corticosteroids to prevent corneal graft rejection following subconjunctival injection provided initially during transplant surgery. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles containing dexamethasone sodium phosphate (DSP) exhibited a size of 200 nm, 8 wt.% drug loading, and sustained drug release over 15 days in vitro under sink conditions. DSP-loaded nanoparticles provided sustained ocular drug levels for at least 7 days after subconjunctival administration in rats, and prevented corneal allograft rejection over the entire 9-week study when administered weekly. In contrast, control treatment groups that received weekly injections of either placebo nanoparticles, saline, or DSP in solution demonstrated corneal graft rejection accompanied by severe corneal edema, neovascularization and opacity that occurred in ≤ 4 weeks. Local controlled release of corticosteroids may reduce the rate of corneal graft rejection, perhaps especially in the days immediately following surgery when risk of rejection is highest and when typical steroid eye drop administration requirements are particularly onerous.

Influence of donor age, post-mortem time and cold storage on metabolic profile of human cornea

PURPOSE

Limited knowledge exists about the influence of donor age and death-to-preservation interval (DPI) on the metabolic properties of the cornea. The aim of this study is to investigate the relationship between both factors and metabolite content of the cornea.

METHODS

Corneas from 15 human donors (age: 41-78 years) were obtained within 16 hrs post-mortem and kept in cold storage for 8 days. The metabolic profiles of the samples were investigated using high-resolution, magic angle spinning (1) H nuclear magnetic resonance spectroscopy before and after 8 days of preservation.

RESULTS

Twenty-two metabolites were detected and assigned in the corneal spectra. The significant metabolic differences before and after hypothermic storage were revealed between younger and older donors. DPI-related significant differences revealed before preservation of the corneas were not displayed after 8 days of cold storage.

CONCLUSIONS

Age of donor as well as post-mortem time influences the biochemical properties of the cornea. Cold storage decreases the metabolite differences between the tissues collected at different post-mortem time.