Postoperative Complications After Primary Adult Optical Penetrating Keratoplasty: Prevalence and Impact on Graft Survival

Corneal blindness in the developing world: The role of prevention strategies

Corneal blindness is an important contributor to the burden of global blindness and has a greater prevalence in low-income countries of the developing world where resources and infrastructure are limited. The causes of corneal blindness too are different from high-income countries and include infectious keratitis, ocular trauma, and xerophthalmia. Persons with these indications tend to have unfavourable outcomes after corneal transplantation, limiting their chances of benefitting from this sight-saving procedure. However, most causes of corneal blindness in the developing world are preventable. This highlights the importance of understanding the unique challenges in these regions and the need for targeted interventions. This article discusses various prevention strategies, including primordial, primary, and secondary prevention, aimed at reducing the burden of corneal blindness in low-income countries. These include capacity building, training, and awareness campaigns to reduce the risk factors of ocular trauma, infectious keratitis, and to improve access to first aid. It is also important to promote safe eye practices and tackle nutritional deficiencies through public health interventions and policy changes. Providing the required training to general ophthalmologists in the management of basic corneal surgeries and diseases and enhancing the accessibility of eye care services in rural areas will ensure early treatment and prevent sequelae. Current treatment modalities belong to the tertiary level of prevention and are largely limited to corneal transplantation. In developing nations, there is a scarcity of donor corneal tissue necessitating an urgent expansion of eye banking services. Alternative approaches to corneal transplantation such as 3D printed corneas, cultured stem cells, and biomaterials should also be explored to meet this demand. Thus, there is a need for collaborative efforts between healthcare professionals, policymakers, and communities to implement effective prevention strategies and reduce the prevalence of corneal blindness in the developing world.

Evaluation of Schlemm Canal Parameters Using Swept-Source Optical Coherence Tomography in Eyes That Underwent Keratoplasty

OBJECTIVES

In this study, we aimed to evaluate Schlemm canal parameters using anterior segment swept-source optical coherence tomography in eyes that underwent keratoplasty and compare them with keratoconus and healthy control groups.

METHODS

The study included 32 patients who underwent penetrating keratoplasty or deep anterior lamellar keratoplasty once due to keratoconus and age-matched and sex-matched 20 keratoconus patients and 30 healthy controls. In all the patients, a single horizontal image centered on the central cornea was obtained from the nasal and temporal quadrants with low-intensity scanning to visualize Schlemm canal.

RESULTS

There was no statistically significant difference between the groups for age and gender ( P ˃0.05). In the keratoplasty group, the area and diameter of Schlemm canal were 2.266±1.141μm 2 and 160.77±65.08 μm, respectively, in the nasal quadrant and 2.623±1.277 μm 2 and 158.81±68.05 μm, respectively in the temporal quadrant, which were statistically significantly lower compared with other groups ( P <0.001 for all). There was no significant difference between the penetrating and deep anterior lamellar keratoplasty subgroups for Schlemm canal parameters.

CONCLUSION

This is the first study to report anterior segment optical coherence tomography after surgery shows SC parameters that are, on average, less than age-matched and keratoconus controls.

Graft failure rate and complications after Descemet membrane endothelial keratoplasty in eyes with pre-existing glaucoma

PURPOSE

To evaluate the outcome of Descemet Membrane Endothelial Keratoplasty (DMEK) in eyes with pre-existing glaucoma.

DESIGN

In this retrospective, observational case series we included data of 150 consecutive DMEKs in eyes with pre-existing glaucoma of 150 patients after excluding data of the second treated eye of each patient and of re-DMEKs during follow-up. Cumulative incidences of IOP elevation (IOP > 21 mmHg or ≥ 10 mmHg increase in IOP from preoperative value), post-DMEK glaucoma (need of an additional intervention due to worsening of the IOP), graft rejection, and graft failure rate were analyzed using Kaplan-Meier survival analysis. COX regression analysis was used to evaluate independent risk factors.

RESULTS

The 36-month cumulative incidence of IOP elevation was 53.5% [95 CI 43.5-63.5%] and of post-DMEK glaucoma 36.3% [95 CI 26.3-46.3%]. Graft rejection occurred with a 36-month cumulative incidence of 9.2% [CI 95% 2.3-16.1]. None of the analyzed risk factors increased the risk for the development of graft rejection. The 36-month cumulative incidence of graft failure was 16.6% [CI 95% 8.4-24.8]. Independent risk factors for graft failure were the indication for DMEK "status after graft failure" (n = 16) compared to Fuchs' dystrophy (n = 74) (p = 0.045, HR 8.511 [CI 95% 1.054-68.756]) and pre-existing filtrating surgery via glaucoma drainage device (GDD) (n = 10) compared to no surgery/iridectomy (n = 109) (p = 0.014, HR 6.273 [CI 95% 1.456-27.031]).

CONCLUSION

The risks of postoperative complications (IOP elevation, post-DMEK glaucoma, graft rejection, and graft failure) in patients with pre-existing glaucoma are high. In particular, pre-existing filtrating surgery via GDD implantation-but not trabeculectomy-and DMEK after graft failure increase the risk of graft failure.

Preservation of donor corneal epithelium in McCarey-Kaufman medium

Purpose:

To evaluate the role of McCarey-Kaufman (MK) medium in maintaining the integrity of donor corneal epithelium.

Methods:

Nineteen corneal buttons were harvested and stored in MK media at 2°C–8°C for four days. Serial photographs were done every day till the 3^rd day, and images were then analyzed with ImageJ software (LOCI, University of Wisconsin, USA). The area of exposure and epithelial defect (ED) was calculated every day for each corneal button.

Results:

The average age of the donors was 56.5 ± 22.7 years and mean time from death to preservation of the corneal buttons was 7.7 ± 3.1 hours. The average corneal area was 145.6 ± 18.8 mm². The total mean area of exposure was 3.6 ± 4.8, 7.2 ± 9.2, and 9.0 ± 11.9 mm², and ED was 1.7 ± 4.6, 2.8 ± 5.3, and 3.3 ± 5.9 mm² on days 1, 2, and 3, respectively. The percentage of increase in the area of exposure and ED in MK media was 3.71% and 1.1% from day 1 to day 3, respectively. Six out of 19 corneal buttons (31.57%) were utilized for keratoplasties, of which two were utilized in house and four were distributed outside. Of the two utilized corneas, none had epithelial defect on postoperative day 1. Rest 13 corneas were either used for training and research purposes, stored in glycerol media, or discarded.

Conclusion:

Since the percentage change in area of exposure/ED is not much at the end of day 3, corneas stored in MK media can be safely used even after three days of storage. Hence, MK medium serves as an excellent medium in maintaining the integrity of donor corneal epithelium.

Long-term Results of Intraocular Pressure Elevation and Post-DMEK Glaucoma After Descemet Membrane Endothelial Keratoplasty

PURPOSE

Intraocular pressure (IOP) elevation occurs regularly after Descemet membrane endothelial keratoplasty (DMEK). This study evaluated the long-term incidence of IOP elevation and post-DMEK glaucoma after DMEK.

METHODS

A total of 463 consecutive DMEKs in 352 patients performed between September 2011 and September 2014 at the Universitätsmedizin-Charité Berlin were reviewed. Data of the second treated eye of each patient and of re-DMEKs during the follow-up were excluded. The 12- and 36-month incidence of IOP elevation and post-DMEK glaucoma was analyzed using the Kaplan-Meier survival analysis. IOP elevation was defined as IOP ≥22 mm Hg or ≥10 mm Hg from preoperative baseline. COX regression analysis was used to evaluate the risk factors for IOP elevation and the development of a post-DMEK glaucoma.

RESULTS

The 12-month incidence of IOP elevation was 15.9% [95 confidence interval (CI), 12.0%-19.8%] and that of post-DMEK glaucoma was 3.9% (95 CI, 1.7%-6.1%); the 36-month incidence was 18.8% (95 CI, 14.5%-23.1%) and that of post-DMEK glaucoma was 6.6% (95 CI, 3.7%-9.5%). The most frequent cause was steroid-induced IOP elevation with a 12-month incidence of 11.7% (95 CI, 8.2%-15.2%) and a 36-month incidence of 12.9% (95 CI, 9.2%-16.6%), respectively. The incidence of postoperative pupillary block IOP elevation was 7.5% (95 CI, 4.8%-10.2%). A preexisting glaucoma increased the risk of IOP elevation [P < 0.001, hazard ratio (HR) 3.331; 95% CI, 1.919-5.782] and the development of a post-DMEK glaucoma (P < 0.001, HR 6.633; 95% CI, 2.556-17.215). The preoperative diagnosis also influenced the risk of IOP elevation [Fuchs corneal dystrophy (FED) vs. bullous keratopathy; P = 0.012, HR 2.354; 95% CI, 1.203-4.608] and post-DMEK glaucoma (FED vs. graft failure; P = 0.01, HR 4.412; 95% CI, 1.419-13.723, FED vs. bullous keratopathy; P = 0.09, HR 2.679; 95% CI, 0.858-8.358).

CONCLUSIONS

Incidence of IOP elevation is high in the first 12 months after DMEK, especially steroid-induced IOP elevation. Steroid-induced IOP elevation could be treated effectively by tapering down the steroid medication or changing the steroid drug. A preexisting glaucoma and the preoperative diagnosis increase the risk for an IOP elevation and a post-DMEK glaucoma.

Challenges in the complex management of post-keratoplasty glaucoma

Glaucoma is a serious complication after corneal transplantation and itself a common cause for graft failure and leading cause of vision loss post-keratoplasty due to corneal endothelial decompensation. Endothelial keratoplasty procedures like Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) may be superior to penetrating keratoplasty (PK) regarding the incidence of elevated intraocular pressure (IOP) and development of glaucoma. There are indications that regardless of the method of keratoplasty, some corneal diseases like pseudophakic bullous keratopathy, corneal perforation, and graft rejection have a higher risk for developing post-keratoplasty glaucoma than keratoconus and corneal dystrophies and likewise respond less to IOP lowering therapy. In this review, the pathophysiology of post-keratoplasty glaucoma, the diagnostic tools with focus on different devices, and their limitations with regard to measuring IOP and the treatment modalities are presented.

Activation of kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2/antioxidant response element pathway by curcumin enhances the anti-oxidative capacity of corneal endothelial cells

Fuchs endothelial corneal dystrophy is one of the most common indications for corneal transplantation, and impaired anti-oxidative function is observed in corneal endothelial cells (CECs). Curcumin is well-known for its anti-oxidative property; but, no study has examined the effect of curcumin on anti-oxidative therapeutic roles in corneal endothelial disease. In our experiments, oxidative stress 0.25 mM tert-butyl hydroperoxide for 2 h was induced in immortalized human CECs pretreated with curcumin. Cell behavior and viability, reactive oxygen species production, and the protein expression of the kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2(Nrf2)/antioxidant response element (ARE) pathway were examined; the Keap1/Nrf2/ARE pathway is crucial anti-oxidative pathway of curcumin. The results showed that pretreatment with 12.5 μM curcumin significantly reduced the ROS production and improved the survival of CECs under oxidative stress. In addition, curcumin pretreatment significantly increased the expression of nuclear Nrf2, and the productions of superoxide dismutase 1 and heme oxygenase-1, which were the target anti-oxidative enzymes of the Keap1/Nrf2/ARE pathway. Our findings showed that curcumin enhanced the growth and differentiation of CECs under oxidative stress. The activation of Keap1/Nrf2/ARE pathway by curcumin was crucial for CECs to improve their anti-oxidative capacity.

Prevalence and risk factors to develop ocular hypertension and glaucoma after penetrating keratoplasty

OBJECTIVE

To determine the prevalence and factors associated with the development of ocular hypertension and glaucoma, in patients undergoing penetrating keratoplasty, in the Eye Clinic of the city of Bogotá.

METHOD

A retrospective cross-sectional study was conducted, and 130 eyes of patients undergoing penetrating keratoplasty were analyzed at the Eye Clinic in Bogotá, between January 2015 and August 2018. Demographic and clinical data were obtained, and it was determined by bivariate analysis, the association factors and the prevalence of the pathology under study.

RESULTS

Prevalence of ocular hypertension was 27.69% and glaucoma 10%. Average age 48.93 ± 18.63 years; higher frequency of presentation in men (61.5%). Statistically significant association factors were male sex (PR 2.59), presence of peripheral anterior synechiae (PR 1.83), history of trauma (PR 2.16), prior PK (PR 2.10) and graft failure (PR 2.04). Post-KP glaucoma only had statistically significant association with bullous keratopathy (PR 2.76).

CONCLUSIONS

Ocular hypertension and glaucoma had a high prevalence after penetrating keratoplasty, and the association factors were similar to those reported in other international studies. Knowing these factors, allows focusing surveillance and treatment in these patients to avoid blindness due to damage of the optic nerve or corneal graft.

Prevalence and risk factors to develop ocular hypertension and glaucoma after penetrating keratoplasty

OBJECTIVE

To determine the prevalence and factors associated with the development of ocular hypertension and glaucoma, in patients undergoing penetrating keratoplasty, in the Eye Clinic of the city of Bogotá.

METHOD

A retrospective cross-sectional study was conducted, and 130 eyes of patients undergoing penetrating keratoplasty were analyzed at the Eye Clinic in Bogotá, between January 2015 and August 2018. Demographic and clinical data were obtained, and it was determined by bivariate analysis, the association factors and the prevalence of the pathology under study.

RESULTS

Prevalence of ocular hypertension was 27.69% and glaucoma 10%. Average age 48.93 ± 18.63 years; higher frequency of presentation in men (61.5%). Statistically significant association factors were male sex (PR 2.59), presence of peripheral anterior synechiae (PR 1.83), history of trauma (PR 2.16), prior PK (PR 2.10) and graft failure (PR 2.04). Post-KP glaucoma only had statistically significant association with bullous keratopathy (PR 2.76).

CONCLUSIONS

Ocular hypertension and glaucoma had a high prevalence after penetrating keratoplasty, and the association factors were similar to those reported in other international studies. Knowing these factors, allows focusing surveillance and treatment in these patients to avoid blindness due to damage of the optic nerve or corneal graft.

Indications, surgical procedures and outcomes of keratoplasty at a Tertiary University-based hospital: a review of 10 years' experience

OBJECTIVE

To investigate keratoplasty outcomes in a university-based hospital.

METHODS

Medical records of all patients undergoing keratoplasty at King Abdulaziz University Hospital, Riyadh, Saudi Arabia, between January 1, 2006, and December 31, 2015, with a minimum follow-up period of three months were reviewed retrospectively. Indications, surgical procedures, complications and outcomes of all surgeries were collected and analyzed.

MAIN OUTCOME MEASURES

Graft survival and visual acuity.

RESULTS

Data were available for 488 grafts in the study period, including 313 optical penetrating keratoplasty (PKP), 42 therapeutic/tectonic PKPs, 72 deep anterior lamellar keratoplasty, 58 Descemet's stripping automated endothelial keratoplasty and 3 Descemet's membrane endothelial keratoplasty. A total of 389 (79.7%) grafts survived, whereas 99 (20.3%) grafts failed. The projected 1-year, 3-year and 5-year cumulative survival rates for the entire study group were 85.8%, 74.9% and 71.1%, respectively. Corneal ectasia was the commonest surgical indication accounting for 48% of the cases. The best long-term survival rates were observed in the stromal dystrophy and corneal ectasia groups. The worst survival rates were noticed in the congenital corneal opacities group. Vision improved in in 57.5% of grafted eyes, remained the same in 39.8% and deteriorated in 2.7%. Postoperative complications occurred in 36% of the grafts with rejection being the most common, and its mere occurrence increased the risk of graft failure by 20-fold.

CONCLUSION

The outcome of grafting in a university-based hospital can be excellent in low-risk grafts and fair to low in high-risk grafts. Our results are relatively comparable to nationally and internationally reported outcomes.

[Anterior stromal micropuncture for the treatment of persistent corneal epithelial graft defects after penetrating keratoplasty]

Persistent corneal graft erosion or persistent epithelial corneal defect is a frequent complication of penetrating keratoplasty. Its development can be contributed by the dry eye syndrome, rare blinking, lagophthalmos, symblepharon, viral infection, autoimmune aggression, and the use of epithelial-toxic eye drops. The article presents three clinical observations of patients who developed persistent corneal graft erosion after penetrating keratoplasty. Due to the ineffectiveness of local conservative therapy for more than 3 weeks, anterior stromal corneal micropuncture was performed. After the procedure, there was a gradual epithelial proliferation, complete healing of the corneal surface was observed 10-16 days after the manipulation, the follow-up period was at least 1 year. The mechanism of action of stromal micropuncture is associated with the creation of a porous surface with better adhesion properties, as well as with the activation of the production of extracellular matrix glycoproteins such as fibronectin, type IV collagen and laminin, which are necessary for stable adhesion of the epithelium. The use of stromal micropuncture of the donor flap in the treatment of post-keratoplasty persistent corneal epithelial defect was proposed for the first time.

[Modern biotechnological treatment methods of persistent corneal epithelial defects]

The article reviews modern methods of treatment of persistent corneal epithelial defects and considers the factors involved in the development of this pathology, including the limbal stem cell deficiency, which is likely to play the main role. The most promising treatment methods are described, particularly the use of blood derivatives and cell therapy.

Long-Term Results of Femtosecond Laser-Enabled Keratoplasty With Zig-Zag Trephination

PURPOSE

To report long-term visual and astigmatism outcomes in cases of zig-zag femtosecond laser-enabled penetrating keratoplasty (FLEK).

METHODS

Retrospective review. Three hundred thirty-five eyes of 287 patients underwent (FLEK) with a zig-zag incision pattern. Patients were assessed preoperatively and underwent postoperative comprehensive examinations at standard intervals of 1, 3, 6, 9, and 12 months, and 6 months thereafter. Postoperative uncorrected distance visual acuity and spectacle-corrected distance visual acuity and manifest and topographical (Mrx cyl and Topo cyl) astigmatism were compared with preoperative values.

RESULTS

Three hundred thirty-five eyes received FLEK with zig-zag configuration. Data are presented for the last recorded visit before any refractive procedure. Sutures were removed in 202 of 335 eyes at an average time to removal of 1.3 ± 1.1 years, and a mean follow-up period of 2.9 ± 2.1 years (range 0-10 years). After full suture removal, mean uncorrected distance visual acuity and spectacle-corrected distance visual acuity were logarithm of the minimum angle of resolution 0.84 (Snellen 20/138) ± 0.55 and 0.33 (Snellen 20/42) ± 0.33, respectively. Mean Mrx cyl and Topo cyl of these groups were 3.38 ± 2.22 and 4.77 ± 3.15, respectively. Of the total number of grafts, the rate of graft rejections was 14.0%, and the failure rate was 5.6%.

CONCLUSIONS

The femtosecond laser-generated zig-zag-shaped incision results in lower manifest and topographical astigmatism than the reported average for conventional penetrating keratoplasty. Graft rejection and failure rates are similar to published data for conventional penetrating keratoplasty.

Epithelial defects after penetrating keratoplasty in infectious keratitis: An analysis of characteristics and risk factors

To investigate the clinical characteristics, treatment, risk factors of occurrence and graft transparency of corneal epithelial defects after penetrating keratoplasty in patients with infectious keratitis. 594 patients (594 eyes) with infectious keratitis treated by penetrating keratoplasty at Shandong Eye Institute were reviewed retrospectively between January 2008 and January 2018. We investigated the demographic data, diameter and sources of graft, onset time, location, scope, time of healing and treatment of epithelial defects, as well as other postoperative complications and graft clarity. 114 of the 594 grafts (19.2%) that developed epithelial defects were included in the epithelial defects group, while the other 480 patients were classified in the non-defect group. The mean age of patients with epithelial defects was statistically greater than that of patients without epithelial defects (P = 0.006). The epithelial defects group accounted for a larger proportion of male patients (P<0.001). The proportion of patients with a graft diameter >9mm in the epithelial defect group (29.8%) was more than that in the non-defects group (16.3%) (P = 0.001). The incidence of epithelial defects significantly differed among the pathogenic causes of infectious keratitis (P = 0.002). The incidence of graft infection (21.1%, 9.2%, respectively, P<0.001) and graft dysfunction (7.9%, 2.5%, respectively, P = 0.012) in the epithelial defect group was higher than in the non-defects group. Multivariate logistic regression revealed that male sex (P = 0.001), age ≥ 60 years (P = 0.024), graft diameter >9mm (P = 0.001), bacterial (P = 0.039) and herpes simplex keratitis (P = 0.008), rheumatism (P = 0.031) and cancer treated with chemo- or radiotherapy (P = 0.032) were independent risk factors for epithelial defects. Graft clarity after epithelial defects were significantly differed between fungal and viral infections (P<0.001). We found that being an elderly male patient, a graft diameter >9 mm, bacterial and viral keratitis and systemic diseases (including rheumatism and cancer treated with chemo- or radiotherapy) were independent risk factors for postoperative epithelial defects.

"Wet" transepithelial phototherapeutic keratectomy in the management of persistent epithelial defects in the graft

Purpose

This study aimed to evaluate the efficacy of “wet” transepithelial phototherapeutic keratectomy (TE-PTK) for treating persistent epithelial defects (PEDs) in the corneal graft following penetrating keratoplasty (PKP).

Methods

This study describes a noncomparative, prospective interventional case series. Patients with post-PKP graft epithelial defects lasting >3 months despite previous treatments with extensive wear soft contact lenses, amniotic membrane transplantation, and tarsorrhaphy were treated with wet TE-PTK. A wet TE-PTK procedure including a “wet ablation” step was performed using the EC-5000 excimer laser. Follow-up visits were at post-PTK days 3, 5, 10, and 30, and at each month thereafter.

Results

Eight patients (8 eyes; 5 men and 3 women; mean age, 51.3±14.3 years; mean follow-up period, 9.1±3.0 months) were included in this study. The mean best-corrected visual acuity was 1.76±0.28 log minimum angle of resolution (logMAR) at baseline and improved to 1.1±0.22 logMAR at 10 days postoperatively (p=0.0156; the improvement was significant). This effect remained stable throughout the remainder of the follow-up period. The mean time from wet TE-PTK to complete reepithelization was 4.3±1.3 days.

Conclusion

Wet TE-PTK appears to be effective for patients with post-PKP PEDs in the corneal graft who have failed conservative measures or previous surgical interventions.

Feeder-free differentiation of cells exhibiting characteristics of corneal endothelium from human induced pluripotent stem cells

The purpose of this study was to devise a strategy for the derivation of corneal endothelial cells (CEnCs) from adult fibroblast-derived induced pluripotent stem cells (iPSCs). IPSCs were generated from an adult human with normal ocular history via expression of OCT4, SOX2, KLF4 and c-MYC Neural crest cells (NCCs) were differentiated from iPSCs via addition of CHIR99021 and SB4315542. NCCs were driven toward a CEnC fate via addition of B27, PDGF-BB and DKK-2 to CEnC media. Differentiation of NCCs and CEnCs was evaluated via rt-PCR, morphological and immunocytochemical analysis. At 17 days post-NCC induction, there were notable changes in cell morphology and upregulation of the neural crest lineage transcripts PAX3, SOX9, TFAP2A, SOX10 and p75NTR and the proteins p75/NGFR and SOX10. Exposure of NCCs to B27, PDGF-BB and DKK-2 induced a shift in morphology from a spindle-shaped neural phenotype to a tightly-packed hexagonal appearance and increased expression of the transcripts ATP1A1, COL8A1, COL8A2, AQP1 and CDH2 and the proteins ZO-1, N-Cad, AQP-1 and Na+/K+ATPase. Replacement of NCC media with CEnC media on day 3, 5 or 8 reduced the differentiation time needed to yield CEnCs. IPSC-derived CEnCs could be used for evaluation of cornea endothelial disease pathophysiology and for testing of novel therapeutics.

Biomaterials for corneal bioengineering

Corneal transplantation is an important surgical treatment for many common corneal diseases. However, a worldwide shortage of tissue from suitable corneal donors has meant that many people are not able to receive sight-restoring operations. In addition, rejection is a major cause of corneal transplant failure. Bioengineering corneal tissue has recently gained widespread attention. In order to facilitate corneal regeneration, a range of materials is currently being investigated. The ideal substrate requires sufficient tectonic durability, biocompatibility with cultured cellular elements, transparency, and perhaps biodegradability and clinical compliance. This review considers the anatomy and function of the native cornea as a precursor to evaluating a variety of biomaterials for corneal regeneration including key characteristics for optimal material form and function. The integration of appropriate cells with the most appropriate biomaterials is also discussed. Taken together, the information provided offers insight into the requirements for fabricating synthetic and semisynthetic corneas for in vitro modeling of tissue development and disease, pharmaceutical screening, and in vivo application for regenerative medicine.

Angiogenesis and lymphangiogenesis in corneal transplantation-A review

Corneal transplantation has been proven effective for returning the gift of sight to those affected by corneal disorders such as opacity, injury, and infections that are a leading cause of blindness. Immune privilege plays an important role in the success of corneal transplantation procedures; however, immune rejection reactions do occur, and they, in conjunction with a shortage of corneal donor tissue, continue to pose major challenges. Corneal immune privilege is important to the success of corneal transplantation and closely related to the avascular nature of the cornea. Corneal avascularity may be disrupted by the processes of angiogenesis and lymphangiogenesis, and for this reason, these phenomena have been a focus of research in recent years. Through this research, therapies addressing certain rejection reactions related to angiogenesis have been developed and implemented. Corneal donor tissue shortages also have been addressed by the development of new materials to replace the human donor cornea. These advancements, along with other improvements in the corneal transplantation procedure, have contributed to an improved success rate for corneal transplantation. We summarize recent developments and improvements in corneal transplantation, including the current understanding of angiogenesis mechanisms, the anti-angiogenic and anti-lymphangiogenic factors identified to date, and the new materials being used. Additionally, we discuss future directions for research in corneal transplantation.

Outcome of repeat penetrating keratoplasty in eyes with failed penetrating keratoplasty

Objectives:

To report the outcomes of penetrating keratoplasty (PKP) surgeries in eyes with failed PKP.

Methods:

This was a retrospective, non-comparative, descriptive case series. Thirty eyes of 30 patients with failed PKP comprised our study group, they were reviewed from January 2007 to December 2012 at the King Khaled Eye Specialist Hospital, Riyadh, Kingdom of Saudi Arabia. Data were collected on best corrected visual acuity before and after one week, one month, 3 months, 6 months, one year, and 2 years following PKP. Intraoperative and postoperative complications, changes in intraocular pressure (IOP), additional surgical procedure and other ocular comorbidities were also documented. The visual outcomes at 6 months and one year were associated with risk factors.

Results:

Before intervention, 18 (60%) eyes had vision <20/400. Vision was 20/20 to 20/60 in 10 (30%) eyes at 6 months, 17 (57%) eyes at 12 months, and 22 (73%) eyes at 24 months. The variation in IOP at different follow up periods was not significant (p=0.2). The presence of other ocular comorbidity was not significantly associated with functional visual outcome (p=0.4). Additional surgical procedure after repeat PKP enabled a regain of excellent vision in 9 (47%) eyes at one year. The numbers for past corneal surgeries were significantly associated with the visual outcome at 6 months.

Conclusion:

Penetrating keratoplasty to manage failed PKP resulted in reducing visual disabilities.

Glaucoma after corneal replacement

Glaucoma is a well-known complication after corneal transplantation surgery. Traditional corneal transplantation surgery, specifically penetrating keratoplasty, has been slowly replaced by the advent of new corneal transplantation procedures: primarily lamellar keratoplasties. There has also been an emergence of keratoprosthesis implants for eyes that are high risk of failure with penetrating keratoplasty. Consequently, there are different rates of glaucoma, pathogenesis, and potential treatment in the form of medical, laser, or surgical therapy.

Intraocular Pressure and Big Bubble Diameter in Deep Anterior Lamellar Keratoplasty: An Ex-Vivo Microscope-Integrated OCT With Heads-Up Display Study

PURPOSE

To investigate the relationship between intraocular pressure (IOP) and big bubble (BB) formation in a model of deep anterior lamellar keratoplasty (DALK).

DESIGN

Ex-vivo.

METHODS

Corneoscleral buttons from human donors were loaded onto an artificial anterior chamber connected to a column of balanced salt solution. A surgeon-in-training learned to perform DALK via the BB technique using swept-source microscope-integrated optical coherence tomography (SS-MIOCT) with heads-up display (HUD). DALK procedures were performed at 6 different IOPs (5, 10, 15, 20, 30, or 40 mm Hg; n = 6 per group) in a randomized fashion, with the surgeon-in-training masked to the pressure and guided by SS-MIOCT with HUD. For a subset of corneas within each pressure group, DALK was performed on matching donor tissue at a control IOP. BB diameter was recorded, and a diameter exceeding the trephine diameter was considered optimal.

RESULTS

Wilcoxon rank sum test showed a difference in BB diameter among the different pressure groups (mean ± SD of 7.75 ± 1.60, 8.33 ± 1.99, 10.9 ± 0.92, 9.08 ± 1.07, 6.67 ± 3.33, and 3.42 ± 3.77 mm in the 5, 10, 15, 20, 30, and 40 mm Hg groups, respectively; P = 0.0014). Per Tukey test, this difference was attributable to comparisons between the 40 mm Hg group and the 5, 10, 15, or 20 mm Hg groups (P = 0.04, 0.02, 0.0001, 0.004, respectively).

CONCLUSIONS

In this ex-vivo model of DALK, the BB technique guided by SS-MIOCT with HUD yielded bubbles of optimal diameters only at physiologic pressures (10‒20 mm Hg). Extremely high IOP (40 mm Hg) resulted in BBs of significantly smaller diameter than BBs obtained at physiologic and low (5 mm Hg) IOPs.

Incidence and risk factors for post-penetrating keratoplasty glaucoma: A systematic review and meta-analysis

Objectives

To establish the incidence and risk factors for post penetrating keratoplasty glaucoma (PKKG).

Methods

Studies published between 1947 and 2016 regarding penetrating keratoplasty (PK) were identified using an electronic search and reviewed. For search purpose, PKKG was defined as ocular hypertension (> 21mmHg) after PK. The incidence and risk factors of PKKG were extracted for all studies. Pooled incidence, odd ratios (ORs) and 95% confidence intervals (CIs) were calculated.

Results

Thirty studies reporting on 27146 patients were included in the analysis of the incidence and risk factors for PKKG. Exact PKKG definitions used in the literature could be classified in to three subgroups: I, ocular hypertension (> 21mmHg) after PK; II, I plus > 4 weeks medical treatment required; III, II plus treatment escalation among patients with preexisting glaucoma. Overall (Definition I) pooled incidence in all studies was 21.5% (95% CI 17.8%, 25.7%). The incidence varied according to different definitions. The highest incidence value was found when only studies using Goldmann tonometer were included (22.5%), while the lowest incidence was found when a strict definition was used and steroid-induced PPKG was excluded (12.1%). The incidence was higher in patients with preexisting glaucoma, bullous keratopathy (BK), aphakia, pseudophakia, failed graft, and surgical indication of trauma. A triple procedure (combined PK with extra capsular cataract extraction and intraocular lens implantation) was not identified as being associated with the increased risk for PKKG.

Conclusions

The overall pooled incidence of PKKG was 21.5%, but it varied according to the criteria used to define the presence of PPKG. Strong risk factors for PKKG included preexisting glaucoma and aphakia, while modest predictors included pseudophakia, regrafting, and preoperative diagnosis like BK and trauma. There may not be sufficient evidence to identify a significant association between a triple procedure and PKKG.

Preservation of the Corneal Epithelium in Different Corneal Storage Media

PURPOSE

With increasing time, epithelial defects (EDs) develop in virtually all corneas stored in corneal storage media. Optisol GS and Life 4°C are commonly available intermediate storage media used for corneal storage before keratoplasty. Epithelial preservation capabilities of Life 4°C and Optisol GS are compared in this study.

METHODS

Nine pairs of human corneas were harvested, and 1 cornea of each pair was stored in Optisol GS and the other was stored in Life 4°C. The size and frequency of EDs of corneas stored in Optisol GS and Life 4°C were measured over time within the chambers using a backlit approach for 14 to 17 days of storage.

RESULTS

At poststorage days 4, 8, and 12, there were no statistical differences in the percent change in the area of the ED between both groups. Of corneas without initial EDs, 6 of 7 (85.7%) stored in Optisol GS and 5 of 8 (62.5%) stored in Life 4°C developed an ED by the end of the assessment period. At the end of the observation period, there was no significant difference in the change in the percent area of the ED between corneas stored in Optisol GS and Life 4°C [4.3% ± 6.6% and 2.1% ± 2.6%, respectively (P = 0.38)].

CONCLUSIONS

Optisol GS and Life 4°C storage media did not significantly differ in their abilities to preserve the corneal epithelium of the donor tissue for up to 17 days. Most corneas stored in both cold-storage media developed EDs within the 14-day observation period.

Incidence of Intraocular Pressure Elevation and Glaucoma after Lamellar versus Full-Thickness Penetrating Keratoplasty

PURPOSE

To analyze the cumulated incidence of glaucoma after penetrating keratoplasty (PK), anterior lamellar keratoplasty (ALK), and endothelial keratoplasty (EK).

DESIGN

Cohort study. Data were recorded prospectively and analyzed retrospectively.

PARTICIPANTS

A total of 1657 consecutive eyes of 1657 patients undergoing corneal transplantation between 1992 and 2013.

METHODS

Penetrating keratoplasty (date range, 1992-2013), ALK (date range, 2002-2013), and Descemet's stripping automated EK (date range, 2006-2013).

MAIN OUTCOME MEASURES

Postoperative intraocular pressure (IOP), glaucoma treatments, and glaucoma-related loss of vision (loss of central visual function resulting in absence of light perception or light perception limited to the temporal visual field). Cox proportional hazard regression model was used to analyze risk factors for glaucoma after keratoplasty.

RESULTS

The 10-year cumulated incidence of elevated IOP and elevated IOP requiring treatment was 46.5% and 38.7%, respectively. In multivariate analysis, 4 variables were significantly associated with a higher incidence of elevated IOP requiring treatment after keratoplasty: preoperative glaucoma or IOP >20 mmHg (adjusted hazard ratio [HR], 1.56; P < 0.001), penetrating keratoplasty (PK) (adjusted HR, 1.12 vs. ALK and 1.10 vs. EK; P < 0.001), postoperative lens status (adjusted HR vs. phakic eyes: 1.15 for posterior chamber intraocular lens, 1.43 for anterior chamber intraocular lens [IOL], 2.83 for aphakic eyes; P < 0.001), and IOL exchange or removal during surgery (adjusted HR, 1.48; P < 0.001). Recipient age, preoperative diagnosis, filtering surgery before keratoplasty, vitrectomy associated with keratoplasty, and filtering surgery associated with keratoplasty were significantly associated with a higher incidence of elevated IOP requiring treatment after keratoplasty in univariate analysis but not in multivariate analysis. The 10-year probability of loss of vision related to glaucoma was 1.0% after EK, 2.1% after ALK, and 3.6% after PK (P = 0.036).

CONCLUSIONS

The incidence of elevation of IOP after keratoplasty and development of glaucoma are significantly decreased with ALK and EK compared with PK. We believe this is due to diminished surgery-induced damage to the anterior chamber angle and trabecular meshwork, and reduced postoperative use of steroids.

Corneal transplantation and glaucoma

Glaucoma is the leading cause of irreversible vision loss post-keratoplasty and an important cause of graft failure. With newer techniques, such as lamellar, endothelial, and laser-assisted keratoplasty as well as keratoprosthesis gaining popularity, clinicians will need to consider the incidence, risks, evaluation, and management of glaucoma for each type of keratoplasty when determining which type of transplant may be most appropriate. A comprehensive literature search of glaucoma in the setting of corneal transplantation was performed and serves as the basis for this review. Preexisting glaucoma and aphakia are notable risk factors. Patients that are candidates for deep anterior lamellar keratoplasty may benefit from reduced rates of post-keratoplasty glaucoma. Although glaucoma also complicates eyes with Descemet stripping endothelial keratoplasty, the severity is less and the intraocular pressure is more easily controlled when compared to penetrating keratoplasty. Endothelial keratoplasty creates unique perioperative issues mostly related to management of anterior chamber air bubbles.

Corneal tissue engineering: recent advances and future perspectives

To address the growing need for corneal transplants two main approaches are being pursued: allogenic and synthetic materials. Allogenic tissue from human donors is currently the preferred choice; however, there is a worldwide shortage in donated corneal tissue. In addition, tissue rejection often limits the long-term success of this approach. Alternatively, synthetic homologs to donor corneal grafts are primarily considered temporary replacements until suitable donor tissue becomes available, as they result in a high incidence of graft failure. Tissue engineered cornea analogs would provide effective cornea tissue substitutes and alternatives to address the need to reduce animal testing of commercial products. Recent progress toward these needs is reviewed here, along with future perspectives.

Spontaneous wound dehiscence after penetrating keratoplasty

Spontaneous wound separation may be developed even months after suture removal especially in the context of long-term corticosteroid therapy. A 68-year-old Caucasian woman presented to our cornea clinic with spontaneous wound dehiscence after her third penetrating keratoplasty (PKP) which was performed three years ago. An Ahmed glaucoma valve (New World Medical, Ranchos Cucamonga, CA) was inserted ten months after the third PKP, which successfully controlled intraocular pressure (IOP). At the examination, the last sutures were removed eight months ago and she was using flourometholone 0.1 % (Sina Darou, Tehran, Iran) with a dose of once a day. There was one quadrant of wound dehiscence from 8 to 11 òclock associated with anterior wound gape and severe corneal edema. Resuturing was performed for the patient. At the one month examination, the corneal edema was resolved and best corrected visual acuity was 20/200 mainly due to previous glaucomatous optic neuropathy. Caution about the prolonged use of corticosteroids is necessary. Topical immunosuppressives could be a promising choice in this field.

Clinical outcome of repeat penetrating keratoplasty

PURPOSE

To compare the clinical outcome of regrafts with first grafts.

METHODS

Two-year outcome data were obtained from the Swedish Cornea Transplant Register for patients undergoing penetrating keratoplasty between 2001 and 2008. Only data from the 3 centers with follow-up return rates >75% were included. The survival and visual outcome of regrafts with the original diagnoses of keratoconus, Fuchs endothelial dystrophy (FED), or bullous keratopathy (BK) were compared with first grafts for the same diagnoses by univariate and logistic regression methods.

RESULTS

For keratoconus, the failure rate increased 3-fold in regrafts compared with first grafts (ie, 17% vs. 6%; P = 0.002) and doubled in FED regrafts (33% vs. 15%; P = 0.001). In BK, the failure rate was already high in first grafts, and the increase in failure of regrafts was minimal (P = 0.9). Visual acuity was also worse in regrafts compared with first grafts, mainly in the keratoconus and FED patients. In the keratoconus group, visual acuity with preferred correction was ≥0.5 in 69% of first grafts compared with only 55% in regrafts (P = 001). In FED, 52% of first grafts but only 19% of regrafts achieved visual acuity ≥ 0.5 (P = 0.001). The visual outcome of regrafts in BK was poor but little different from first grafts where fewer than 20% achieved visual acuity ≥ 0.5.

CONCLUSIONS

This analysis confirmed the poorer survival of regrafts where the original indication was keratoconus or FED. In addition, visual outcome was also worse than in the first grafts. However, the outcomes of regrafts in BK were similar to first grafts.

Outcome of corneal transplantation in a private institution in Saudi Arabia

Background

The aim of this work was to describe the indications, complications, and outcomes of penetrating keratoplasty (PKP) in Saudi Arabia.

Methods

In a retrospective, noncomparative interventional case series, the medical records of patients who underwent PKP from January 2000 to December 2008 and had a minimum follow-up of 6 months were reviewed. All corneas were obtained from eye banks in the US. Indications, complications, and outcomes of surgery were recorded. This study was approved by the institutional review board.

Results

Eighty-five consecutive eyes were included in this study. There were 52 (61.2%) males and 33 (38.8%) females. The median age was 35.0 years (range 3–85 years), and the median follow-up period was 24 months (range 6–108 months). The indications for PKP were keratoconus, bullous keratopathy, corneal scars, corneal dystrophy, and corneal regraft. The overall graft survival time was 88.9 months ± 4.9 months (mean ± standard error of mean, 95% confidence interval [CI] 79.4 months –98.4 months) while the 3-year and 5-year cumulative survival rates were 90.7% and 84.3%, respectively. Surgical indication (P = 0.038), immune rejection (P < 0.001), preoperative corneal vascularization (P = 0.022), and perioperative high intraocular pressure (P = 0.032) were associated significantly with corneal graft failure in univariate analysis. Multivariate analysis reduced these significant associations to rejection (P < 0.001) and vascularization (P = 0.009). Relative risk for failure in rejected cornea was 16.22 (95% CI 4.99–52.69) and in vascularized cornea was 3.89 (95% CI 1.36–11.09). At last visit following PKP, 34 (40%) eyes had best spectacle-corrected visual acuity of 20/40 or better, and 51 (60.0%) eyes had 20/80 or better. Best spectacle-corrected visual acuity was worse than 20/400 in 15 (17.6%) eyes.

Conclusion

The overall corneal graft survival in a private setting in Saudi Arabia can be excellent. Thorough preoperative evaluation and comprehensive postoperative management are crucial for successful corneal transplantation. A larger multicenter study is recommended to portray the outcome of private corneal transplantation in Saudi Arabia in general.

Long-term rejection incidence and reversibility after penetrating and lamellar keratoplasty

PURPOSE

To identify risk factors for corneal graft rejection and rejection irreversibility.

DESIGN

Retrospective cohort study.

METHODS

setting: Institutional. patients: A total of 1438 consecutive eyes of 1438 patients who underwent corneal transplantation for optical indication at the Centre Hospitalier National d'Ophtalmologie des XV-XX, Paris, France, between December 1992 and December 2010 were studied. Surgical technique was penetrating keratoplasty (PK) in 1209 cases, anterior lamellar keratoplasty (ALK) in 165 cases, and Descemet stripping with endothelial keratoplasty in 64 cases. main outcome measures: Cumulative incidence of rejection episodes and rejection irreversibility rate.

RESULTS

A total of 299 cases of rejection episodes were identified, of which 145 (48.5%) were irreversible after treatment. In multivariate analysis, the cumulative incidence of rejection episodes was influenced by recipient age (P = .00002), recipient rejection risk (P = .0003), lens status (P = .00003), and surgical group (P = .035). A higher incidence of rejection episodes was observed in young patients (<20 years) and patients aged from 41 to 50, high-risk recipients, aphakic eyes and eyes with anterior chamber intraocular lens, and eyes with PK (compared with eyes with ALK). Rejection episodes were more likely to be irreversible for high-risk recipients (P = .02), for eyes with preoperative hypertony (P = .009), and for eyes with poor visual acuity at presentation (P = .002).

CONCLUSIONS

Recipient rejection risk and surgical group are the main risk factors for rejection as they both influence the incidence of rejection and the reversibility rate. Recipient age and lens status are predictive factors for the occurrence of rejection. Preoperative hypertony is a predictive factor for rejection irreversibility.

Candida albicans interface infection after deep anterior lamellar keratoplasty

The clinical features of interface Candida keratitis after deep anterior lamellar keratoplasty (DALK), may imitate rejection or crystalline keratopathy. We report here an 18-year-old woman presented with red eye, 4 months after undergoing DALK. Slit lamp examination revealed keratic precipitates (KPs) and cojunctival injection. She was prescribed corticosteroid treatment for endothelial rejection by another ophthalmologist because of misdiagnosis, but suffered a recurrence of symptoms after reduction of the corticosteroid treatment. At that time, she was referred to our office. The recurrence persisted despite antibiotic and antifungal therapies. Ten days after treatment with interface irrigation with amphotericin, the infiltration and hypopyon were resolved. Topical steroid was added after 3 months of antifungal monotherapy. Irrigant cultures confirmed the presence of Candida albicans. The corneal graft appeared semi-clear with no signs of infection at 17-month follow-up. We recommend a close follow-up and a timely intervention to prevent the need for more invasive treatment such as penetrating keratoplasty.

Intraocular pressure elevation and post-DSEK glaucoma after Descemet`s stripping endothelial keratoplasty

BACKGROUND

Intraocular pressure (IOP) elevation is a common problem in penetrating keratoplasty (PK), and possibly leads to graft failure. IOP elevation and secondary glaucoma may also be present after Descemet`s stripping endothelial keratoplasty (DSEK). This retrospective study analyzes the risk factors for IOP elevation and the functional outcome in those patients with post-DSEK glaucoma.

METHODS

A retrospective analysis of case records of 72 DSEKs between 2007 and 2010 was performed. A total of 59 operated eyes were included. The assessment included the pre-operative history of corneal disease and glaucoma. Furthermore, the response to antiglaucoma treatment, the graft failure, the IOP, and visual acuity development were evaluated.

RESULTS

The incidence of IOP elevation was 28.8 % and of post-DSEK glaucoma 11.9 %. Steroid-induced IOP elevation was the most frequent cause, with an incidence of 18.6 %. Patients with pre-existing glaucoma showed a significantly higher risk of developing IOP elevation, steroid-induced glaucoma and post-DSEK glaucoma (p = 0.006, p = 0.023, p = 0.009). In all cases, IOP elevation was treated effectively by tapering down steroid medication and initiating or increasing antiglaucoma medication. Visual acuity after 6 and 12 months improved significantly in cases with and without pre-existing glaucoma (p < 0.0001). After 24 months, clear grafts were achieved in 53 eyes (89.9 %). There was no significant difference in graft failure rates between cases with or without pre-existing glaucoma (p = 0.581) and with or without post-DSEK glaucoma (p = 0.306).

CONCLUSIONS

IOP elevation after DSEK shows a high incidence. Pre-existing glaucoma increased the risk of developing IOP elevation and post-DSEK glaucoma. Although steroid-induced IOP elevation was the most frequent cause and could be treated effectively by tapering down steroid medication; there are other reasons why post-DSEK glaucoma developed. Management by medical treatment results in good visual acuity and graft survival.

[Severe bacterial keratitis referred to ophthalmology emergency departments: a retrospective study of 268 cases]

PURPOSE

To investigate epidemiological, microbiological and clinical aspects of severe bacterial keratitis, in order to update current understanding of risk factors (RF) and prognosis.

PATIENTS AND METHODS

We conducted a monocentric retrospective study from January 2005 to January 2011, identifying and collecting data from inpatients admitted for severe documented bacterial keratitis.

RESULTS

We found 268 unilateral corneal ulcers. At least one local or systemic risk factor was identified in 255/268 patients (95%). The leading risk factor was contact lens wear (129/268), followed by underlying corneal disease (50/268) and prior corneal surgery (47/268). Initial and final visual acuities were 0.06 and 0.2 (1.20 and 0.72 LogMAR) respectively. Contact lens wear was associated with better prognosis and shorter hospitalization (P<0.05). Corneal healing was obtained in 255/268 patients (95%), with adjuvant surgery for 33 patients. The most frequently isolated pathogens were Gram+ cocci, more commonly associated with degenerative keratopathy or prior corneal surgery, and Gram- bacilli, more commonly associated with contact lenses (P<0.05). Both demonstrated a similar prognosis.

CONCLUSION

Specific risk factors should be investigated in cases of severe bacterial keratitis. Contact lens wear is the most frequent risk factor, but with a better prognosis than underlying corneal disease, prior corneal surgery or systemic risk factors. The specific bacterial pathogen no longer appears to dramatically influence the outcome of severe corneal ulcers.

Ocular surface deficits contributing to persistent epithelial defect after penetrating keratoplasty

PURPOSE

To determine the ocular surface deficits contributing to persistent epithelial defect (PED) after penetrating keratoplasty (PKP).

METHODS

Four ocular surface deficits that contribute to PED and their corrective measures were reviewed in 11 eyes of 11 patients with PED after PKP.

RESULTS

Among these 11 eyes, PED developed early in 8 eyes and late in 3 eyes after PKP. They all had more than 2 ocular surface deficits, with infrequent blinking (11 eyes) and lagophthalmos (9 eyes) being more common. Proper corrective measures resulted in rapid epithelialization in 1 week (1 eye), 2 weeks (9 eyes), and 3 weeks (1 eye) via insertion of a bandage contact lens to maintain tear film for treating infrequent blinking (4 eyes), tarsorrhaphy to correct nocturnal lagophthalmos (2 eyes), and fornix reconstruction to eliminate pathogenic symblepharon (4 eyes). During the follow-up of 22.1 ± 7.6 months after healing of PED, 8 eyes retained a stable and clear graft, whereas 3 eyes with more ocular surface deficits had recurrent PED and graft failure develop. Two of the latter were corrected by a repeat PKP combined with oral mucosal graft to correct the remaining cicatricial eyelids.

CONCLUSIONS

Besides the neurotrophic state and aqueous tear deficiency dry eye common in this cohort, infrequent blinking, lagophthalmos, and pathogenic symblepharon also contribute to PED after PKP. Proper corrective measures and vigilant follow-up are crucial for maintaining PKP graft survival in these severe cicatricial ocular surface diseases.

Corneal transplantation

Corneal transplantation or keratoplasty has developed rapidly in the past 10 years. Penetrating keratoplasty, a procedure consisting of full-thickness replacement of the cornea, has been the dominant procedure for more than half a century, and successfully caters to most causes of corneal blindness. The adoption by specialist surgeons of newer forms of lamellar transplantation surgery, which selectively replace only diseased layers of the cornea, has been a fundamental change in recent years. Deep anterior lamellar keratoplasty is replacing penetrating keratoplasty for disorders affecting the corneal stromal layers, while eliminating the risk of endothelial rejection. Endothelial keratoplasty, which selectively replaces the corneal endothelium in patients with endothelial disease, has resulted in more rapid and predictable visual outcomes. Other emerging therapies are ocular surface reconstruction and artificial cornea (keratoprosthesis) surgery, which have become more widely available because of rapid advances in these techniques. Collectively, these advances have resulted in improved outcomes, and have expanded the number of cases of corneal blindness, which can now be treated successfully. Femtosecond-laser-assisted surgery, bioengineered corneas, and medical treatment for endothelial disease are also likely to play a part in the future.

Glaucoma and corneal transplant procedures

Glaucoma after corneal transplantation is a leading cause of ocular morbidity after penetrating keratoplasty. The incidence reported is highly variable and a number of etiologic factors have been identified. A number of treatment options are available; surgical intervention for IOP control is associated with a high incidence of graft failure. IOP elevation is less frequently seen following deep anterior lamellar keratoplasty. Descemet's striping-automated endothelial keratoplasty is also associated with postprocedure intraocular pressure elevation and secondary glaucoma and presents unique surgical challenges in patients with preexisting glaucoma surgeries. Glaucoma exists in up to three-quarters of patients who undergo keratoprosthesis surgery and the management if often challenging. The aim of this paper is to highlight the incidence, etiology, and management of glaucoma following different corneal transplant procedures. It also focuses on the challenges in the diagnosis of glaucoma and intraocular pressure monitoring in this group of patients.

Glaucoma and corneal transplant procedures

Glaucoma after corneal transplantation is a leading cause of ocular morbidity after penetrating keratoplasty. The incidence reported is highly variable and a number of etiologic factors have been identified. A number of treatment options are available; surgical intervention for IOP control is associated with a high incidence of graft failure. IOP elevation is less frequently seen following deep anterior lamellar keratoplasty. Descemet's striping-automated endothelial keratoplasty is also associated with postprocedure intraocular pressure elevation and secondary glaucoma and presents unique surgical challenges in patients with preexisting glaucoma surgeries. Glaucoma exists in up to three-quarters of patients who undergo keratoprosthesis surgery and the management if often challenging. The aim of this paper is to highlight the incidence, etiology, and management of glaucoma following different corneal transplant procedures. It also focuses on the challenges in the diagnosis of glaucoma and intraocular pressure monitoring in this group of patients.

Penetrating keratoplasty after radial keratotomy and recurrent immune overreaction

A 32-year-old man suffering from keratoconus was treated with radial keratotomy. Twenty weeks later, he presented visual deterioration, edema and corneal perforation. A penetrating keratoplasty was required. The postoperative course was regular, but after 9 months, the patient presented kerato-uveitis. Subsequent phlogistic relapses occurred approximately every 6 months during the following 5 years. The performed cultures were positive only during the first episode. Radial keratotomy is not indicated in keratoconus. The multiple relapses of kerato-uveitis could not be explained by infection, and we hypothesized that they may be due to a ‘traumatic memory’ of the cornea caused by the several suffered traumatisms, without clinical features of corneal graft rejection. The risks of new penetrating keratoplasty and cataract surgery are high. As the cornea is the tissue with the highest sensitivity in the body, we tried to explain the relapsing kerato-uveitis as a consequence of the disruption of the nervous corneal network.