Penetrating keratoplasty for macular corneal dystrophy

Management of Stromal Corneal Dystrophies; Review of the Literature with a Focus on Phototherapeutic Keratectomy and Keratoplasty

Corneal dystrophies are a group of non-inflammatory inherited disorders of the cornea. This review considers treatment options for epithelial-stromal and stromal corneal dystrophies: namely Reis–Bücklers, Thiel–Behnke, lattice, Avellino, granular, macular and Schnyder corneal dystrophies. Where there is visual reduction, treatment options may include either phototherapeutic keratectomy (PTK) or corneal transplantation. Due to the anterior location of the deposits in Reis-Bücklers and Thiel–Behnke dystrophies, PTK is considered the treatment of choice. For lattice, Avellino, granular and macular corneal dystrophies, PTK provides temporary visual improvement; however, with recurrences, repeat PTK or a corneal transplant would be needed. For Schnyder dystrophy, should treatment be required, PTK may be the preferred option due to the potential for recurrence of the disease in corneal transplantation. This review discusses the literature and evidence base for the treatment of corneal dystrophies in terms of visual outcomes and recurrence rate.

Macular corneal dystrophy related to novel mutations of CHST6 in a Chinese family and clinical observation after penetrating keratoplasty

BACKGROUND

Macular corneal dystrophy (MCD) is a rare corneal stromal dystrophy with bilateral progressive vision loss. The pathogenic gene of MCD is carbohydrate sulfotransferase 6 (CHST6). Herein, we report a novel missense mutation and a rare exon deletion mutation in the CHST6 gene in a Chinese family with MCD.

METHODS

Genomic DNA was extracted from the peripheral blood, and next generation sequencing was used to analyse the gene sequence. The pathogenic mutations were identified in all affected family members. The proband successively received binocular penetrating keratoplasty (PKP), and the corneas were examined by histopathology and colloidal iron staining to prove the diagnosis. A long-term follow-up was made to observe the changes after PKP.

RESULTS

Genetic analysis demonstrated hemizygous mutations in the proband, including a novel c.520A>C (p.K174Q) missense mutation and a rarely reported exon 3 deletion mutation, which were co-segregated with the MCD phenotypes in the pedigree. The positive colloidal iron staining confirmed the diagnosis of MCD in the proband. However, the clinical phenotype and pathological manifestation of both eyes were different from each other because of complicated keratitis in the left eye. During the nine years of follow-up, visual acuity was improved significantly, and the cornea was transparent without rejection and postoperative recurrence in both eyes.

CONCLUSIONS

The novel hemizygous mutations were thought to contribute to the loss of CHST6 function, which induced typical clinical and pathological features of MCD. PKP was an effective treatment for MCD.

Medium-Term Clinical Outcomes of Deep Anterior Lamellar Keratoplasty versus Penetrating Keratoplasty for Macular Corneal Dystrophy

Purpose

To compare the postoperative outcomes of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) for macular corneal dystrophy (MCD).

Design

Single-center, retrospective, interventional case series.

Methods

A chart review was performed of 100 patients (157 eyes) who underwent primary DALK (DALK group) and PKP (PKP group) for histopathologically confirmed MCD for whom at least 12 months of follow-up were available. Between-group comparisons were performed of visual acuity (VA), graft survival, and postoperative complications.

Results

There were 22 eyes in the DALK group and 135 in the PKP group. Postoperative best-corrected visual acuity (BCVA) of 20/40 or better was achieved in 90.9% of the DALK group and 76.3% of the PKP group (P=0.12). At last visit, graft survival was 95.5% (21 eyes) and 91.1% (123 eyes) in DALK and PKP groups, respectively (P=0.69, Log rank test). Corneal graft rejection episodes occurred in 1 (4.5%) DALK graft and 19 (14.1%) PKP grafts. Five of the 19 graft rejections in the PKP group were irreversible. Microbial keratitis and cataract occurred in 6 (4.5%) and 15 (11.1%) PKP eyes. One (4.5%) eye in the DALK group had cataract and none of the DALK cases developed microbial keratitis. Clinically significant recurrence was observed in 4 (2.9%) PKP eyes and 1 (4.5%) DALK eye (P=0.69), respectively.

Conclusion

DALK is a viable option for MCD without Descemet membrane involvement. DALK had comparable medium-term visual and survival outcomes to PKP. DALK has the advantage of lower open sky intraoperative complications and lower graft rejection episodes.

Macular Corneal Dystrophy: An Updated Review

Macular Corneal Dystrophy is an autosomal recessive form of corneal dystrophy due to a mutation in CHST6 gene, which results in abnormal proteoglycan synthesis. There is accumulation of abnormal glycosaminoglycans in the corneal stroma and endothelium. The deposition results in progressive loss of corneal transparency and visual acuity. The histopathology shows characteristic alcian blue positive deposits. Management in the cases with visual loss requires keratoplasty either full thickness or lamellar. The decision about the ideal type of keratoplasty depends on age and pre-operative clinical features. Although prognosis after keratoplasty is good, recurrences can occur. Future research should be targeted towards gene therapy in this condition.

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.

Deep anterior lamellar keratoplasty outcomes in macular and granular corneal dystrophy - A comparative cross-sectional study

Purpose

To compare the functional and anatomical outcomes (in terms of graft uptake and rejection/failure) of deep anterior lamellar keratoplasty (DALK) in stromal corneal dystrophy (macular and granular).

Methods

Sixteen eyes with macular corneal dystrophy (MCD; group A) and 10 eyes with granular corneal dystrophy (GCD; group B) underwent successful DALK by big bubble technique or layer-by-layer dissection.

Results

Both groups showed significant improvement in their best-corrected visual acuity postoperatively (postoperative P value in MCD and GCD was 0.00001 and 0.0008, respectively) with no statistically significant differences between the two groups (P = 0.77) at 1 year. Postoperative endothelial count did not drop significantly in group A (MCD, P= 0.1553). Only in seven eyes preoperative endothelial count could be obtained (due to dense stromal corneal opacity), but there was a significant endothelial count difference between preoperative and postoperative count in group B (GCD, P= 0.0405) at the end of 1 year postoperatively which could be because of age and stage of disease (advanced granular dystrophy) and also because of small sample size of GCD compared with MCD. Intergroup comparison between the two groups showed no statistically significant difference (P = 0.6353) with good postoperative outcome in both groups.

Conclusion

DALK can be successfully done in both groups and results are comparable. However, long-term outcomes on a large scale need to be further evaluated.

Keratoconus Associated with Corneal Macular Dystrophy: In vivo Confocal Microscopic Evaluation

Purpose

The authors present a case, studied through in vivo confocal microscopy, of concomitant keratoconus and macular corneal dystrophy (MCD).

Methods

A 29-year-old man underwent a penetrating keratoplasty in the right eye in May 2005. Confocal microscopy was performed to examine the cornea of the right eye.

Results

A diagnosis of concomitant keratoconus and MCD was suspected, due to the simultaneous findings of corneal ectasia and stromal opacities.

Conclusions

In this case, using in vivo confocal microscopy, morphologic changes were detected in many corneal layers and compared with the histopathologic findings. The morphologic alterations were found mainly in the area of the cornea apex.

Prevalence and histopathological characteristics of corneal stromal dystrophies in Saudi Arabia

PURPOSE

The aim was to determine the frequency and describe the main histopathologic features of corneal stromal dystrophy in Saudi Arabia.

METHODS

A single-center, retrospective analysis of 193 corneal specimens diagnosed with stromal dystrophy. All samples were retrieved from the Histopathology Department at King Khaled Eye Specialist Hospital over a 10-year period (2002 to December 31, 2011). Cases of stromal dystrophy undergoing keratoplasty were included in the study. Routine histopathologic stains and specific stains were used to determine a diagnosis. The corresponding demographic data and basic clinical/surgical information were collected via chart review.

RESULTS

The study sample was comprised of 193 eyes. The final diagnoses were macular corneal dystrophy (MCD) in 180 (93.26%) eyes, granular corneal dystrophy (GCD) in 9 (4.66%) and lattice corneal dystrophy (LCD) in 4 (2.07%) eyes. The mean age at presentation was 27.03 years for MCD, 26.33 years for GCD and 53.75 years for LCD. The interval between diagnosis and surgical intervention was not statistically different between the macular and granular groups (P = 0.141). There was a positive family history for the MCD (37.22%) and GCD (44.44%) groups. All eyes underwent penetrating keratoplasty (PKP) except 10 MCD cases that underwent lamellar keratoplasty. Diffuse stromal deposits were present in 87.2% of MCD corneas and 66.67% of GCD corneas. Seventeen eyes with MCD were misdiagnosed as GCD. None of the LCD cases were clinically identified since all of these cases were diagnosed as corneal scarring. In eyes with MCD that underwent PKP, there was diffuse stromal involvement (in 87.22% eyes) and changes in Descemet's membrane (in 53.5% eyes).

CONCLUSION

This pathological study suggested that MCD was the most common corneal stromal dystrophy that required keratoplasty in Saudi Arabia. Patient with MCD and GCD presented at a significantly younger age than LCD. The clinical diagnosis of MCD is not achieved in all cases likely due to a more severe phenotype in the Saudi population or the presence of corneal scarring that is associated with previous trachoma, which obscures the classical appearance of LCD. We believe that PKP is first-line surgical treatment, especially for MCD because it involves all corneal layers. However, deep stromal involvement and changes in Descemet's membrane in MCD should be considered when selecting the surgical procedure.

Clinical outcomes and risk factors for graft failure after deep anterior lamellar keratoplasty and penetrating keratoplasty for macular corneal dystrophy

PURPOSE

The aim of this study was to compare visual acuity, clinical outcomes, complications, and risk factors for graft failure after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy.

METHODS

Retrospective comparative case series.

RESULTS

The PK group consisted of 109 eyes of 84 patients and the DALK group consisted of 21 eyes of 20 patients. The mean logarithm of the minimum angle of resolution best-corrected visual acuity at 3 and 12 months was 0.5 versus 0.5 (P = 0.285) and 0.4 versus 0.4 (P = 0.67) in the DALK and PK groups, respectively. There was no significant statistical difference in astigmatism and spherical equivalent between the 2 groups at 12 months. In the PK group, graft rejection that was the most common cause of graft failure was seen in 27 eyes (25%), of which 55% occurred within 1 year. In the DALK group, Descemet membrane microperforation occurred in 5 eyes (24%) intraoperatively, and early postoperative Descemet membrane detachment with double anterior chamber occurred in 9 eyes (43%). Kaplan-Meier estimate of graft survival in PK versus DALK groups were 93% versus 80% at 1 year and 78% versus 70% at 4 years, respectively.

CONCLUSIONS

Visual and refractive outcomes are comparable between DALK and PK groups. DALK was superior to PK in its safety against postoperative complications such as endothelial rejection and secondary glaucoma. Graft failure in DALK was mostly associated with either intraoperative or early postoperative complications. DALK is a viable surgical option in cases with macular corneal dystrophy.

Corneal blindness and xenotransplantation

Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world's blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies between parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty, and endothelial keratoplasty (EK). Indications for corneal transplantation vary between countries, with Fuchs' dystrophy being the leading indication in the USA and keratoconus in Australia. With the exception of the USA, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, for example stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future.

Macular corneal dystrophy: in vivo confocal and structural data

OBJECTIVE

To demonstrate the corneal morphologic aspects obtained with in vivo confocal microscopy (CM) and light and electron microscopy of specimens obtained from the same patients with macular corneal dystrophy (MCD).

DESIGN

Case series.

PARTICIPANTS

Five consecutive patients affected by MCD undergoing penetrating keratoplasty (PK) in 1 eye.

METHODS

The patients were examined with the slit-lamp, optical pachymetry, and CM before undergoing PK. The corneal buttons were processed for light, transmission, and scanning electron microscopy.

MAIN OUTCOME MEASURES

Corneal in vivo CM, corneal light, and electron microscopy.

RESULTS

Confocal microscopy showed areas of altered reflectivity in basal epithelial cells, which appeared hyperreflective or completely white. In the anterior stroma, rectilinear hyperreflective areas were shown. The stroma was characterized by a granular appearance of both keratocytes and extracellular matrix. Dark striae of different length and orientation were present in the middle and posterior stroma. The corneal endothelium showed polymegethism and cells containing bright granules in their cytoplasm. The histopathologic study demonstrated areas of thickened Bowman's layer covered by an epithelium reduced in height. The Bowman's layer thickenings were due to the accumulation of free or vesiculated material of different electron density. The keratocytes showed intracytoplasmatic vesicles, whereas the extracellular matrix presented a large quantity of intercellular electron-lucent material and parallel lamellae with an undulated course. Occasional macrophages, filled with vesicles of granular-filamentous material and evident podosomes, were observed. Descemet's membrane was formed by a normal anterior banded zone and a posterior nonbanded zone of honeycombed aspect. The endothelial cells showed a large number of intracytoplasmic vesicles.

CONCLUSIONS

The structural changes observed with the histopathologic methods give an account and provide an explanation for the pathologic changes demonstrated by CM in the course of MCD. This may contribute to the understanding of in vivo imaging, allowing a better, noninvasive study of the disease evolution.

Deep anterior lamellar keratoplasty versus penetrating keratoplasty for macular corneal dystrophy: a randomized trial

PURPOSE

To compare outcomes of big-bubble deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy.

DESIGN

Prospective, randomized, interventional case series.

METHODS

setting: Single hospital. patients: Eighty-two eyes of 54 patients requiring keratoplasty for the treatment of macular corneal dystrophy without endothelial involvement were included. main outcome measures: Operative complications, uncorrected visual acuity, best-corrected visual acuity, contrast sensitivity function, higher-order aberrations, and endothelial cell density were evaluated.

RESULTS

The DALK and PK group consisted of 35 and 41 eyes, respectively. Best-corrected visual acuity after surgery was 20/40 or better 68.5% and 70.7% of the eyes in the DALK and PK groups, respectively (P > .05). No statistically significant differences between groups were found in contrast sensitivity function with and without glare for any spatial frequency (P > .05). Significantly higher levels of higher-order aberrations were found in the DALK group (P < .01). In both groups, a progressive and statistically significant reduction in endothelial cell density was found (P < .01). At the last follow-up, the mean endothelial cell loss was 18.1% and 26.9% in DALK and PK groups, respectively (P = .03). Graft rejection episodes were seen in 5 eyes (12.1%) in the PK group, and regrafting was necessary in 3 eyes (7.3%). Recurrence of the disease was documented in 5.7% and 4.8% of the eyes in the DALK and PK groups, respectively.

CONCLUSIONS

Deep anterior lamellar keratoplasty with the big-bubble technique provided comparable visual and optical results as PK and resulted in less endothelial damage, as well as eliminating endothelial rejection in macular corneal dystrophy. Deep anterior lamellar keratoplasty surgery is a viable option for macular corneal dystrophy without endothelial involvement.

Localization and expression of CHST6 and keratan sulfate proteoglycans in the human cornea

Macular corneal dystrophy (MCD; OMIM 217800) is a rare autosomal recessive inherited disorder caused by mutations in the carbohydrate sulfotransferase 6 (CHST6) and characterised by the presence of unsulfated keratan sulfate proteoglycans (KSPGs) forming abnormal deposits that eventually lead to visual impairment. The aim of this study is to understand in which corneal cells CHST6 and KSPGs are expressed and exert their activity. Expression and localization of CHST6, keratan sulfate (KS) and proteins of the KSPGs, such as mimecan and lumican, were assessed both in human cornea sections and in cultured primary keratinocytes (n = 3) and keratocytes (n = 4). Immunohistochemistry, semiquantitative RT-PCR, in situ RNA hybridization and HPLC analysis of glycosaminoglycans were used as read-outs. In human corneas KS was predominantly found in the stroma, but absent, or barely detectable, in the corneal epithelium. A similar pattern of distribution was found in the epidermis, with KS mainly localised in the derma. As expected, in the cornea CHST6 (the gene encoding the enzyme which transfers sulfate residues onto KSPGs) was found expressed in the suprabasal, but not basal, layers of the epithelium, in the stroma and in the endothelium. Analyses of KS by means of HPLC showed that in vitro cultured stromal keratocytes express and secrete more KS than keratinocytes, thus mirroring results observed in vivo. Similarly expression of the CHST6 gene and of KS proteoglycans such as mimecan, lumican is limited to stromal keratocytes. Unlike keratocytes, corneal keratinocytes do not synthesize mimecan or lumican, and express very little, if none, CHST6. Any drug/gene therapy or surgical intervention aimed at curing this rare genetic disorder must therefore involve and target stromal keratocytes. If coupled to the accuracy of HPLC-based assay that we developed to determine the amount of KS in serum, our findings could lead to more targeted therapeutic treatments of the ocular features in MCD patients.

Pharmacologic strategies in the prevention and treatment of corneal transplant rejection

Corneal transplantation remains one of the most successful organ transplantation procedures in humans. The unique structure of the cornea, with its absence of blood vessels and corneal lymphatic, allows the survival of corneal allograft. Recent advances in sutures, storage media, microsurgical instrumentation, and new pharmacological strategies have greatly improved the success of corneal transplantation and the prevention of corneal allograft rejection. Our strategies in the management and prevention of corneal graft rejection can modify and improve the survival of corneal allografts. Preoperative evaluation, understanding the risk factors, and management of ocular surface disorders may greatly improve the survival of the corneal transplant. Early recognition of corneal allograft rejection and aggressive treatment may improve the survival of the corneal graft. Furthermore, patients who undergo corneal transplantation should be maintained under close ophthalmic surveillance and patients should be informed to report immediately whenever symptoms of corneal graft rejection occur. The mainstay of therapy is topical corticosteroids. In severe cases, periocular, intravenous, and oral corticosteroids therapy can be rendered. New therapeutic modalities such as cyclosporine, tacrolimus, daclizumab, mycophenolate mofetil, leflunomide, rapamycin, and others may prove to be of help in the prevention and treatment of corneal graft rejection. Early recognition of corneal graft rejection and prompt treatment are mandatory for the successful survival of the corneal allograft.

Macular corneal dystrophy: mutational spectrum in German patients, novel mutations and therapeutic options

INTRODUCTION

The objective of this study was to investigate genotype-phenotype correlations, the consequences for surgical treatment, and the therapeutical options in patients with macular corneal dystrophy (MCD).

MATERIAL AND METHODS

We investigated MCD genotype by using polymerase chain reaction followed by direct sequencing in one family and four patients with MCD. Results were confirmed by restriction analysis. Clinical phenotypes, histopathological findings, and therapeutical proceedings of each patient were reported and compared with the molecular genetic results.

RESULTS

Five mutations, four missense mutations, and one frameshift mutation, from which three were novel, and one single-nucleotide polymorphism, were identified within the coding region of the CHST6 gene. In three patients, two with a homozygous mutation within the start codon (Met1Leu) and one with a heterozygous mutation (Leu200Arg) and a polymorphism (Arg162Gly), with irregular corneal surface and recurrent erosions a phototherapeutic keratectomy lead to a transient success. An additional fitting of rigid gas permeable contact lenses in one patient could further improve irregular astigmatism. In two patients, one with a frameshift mutation (1734_1735delTG; Arg211Gln) and one with two compound heterozygous mutations (Leu200Arg; Leu173Phe) and an additional polymorphism (Arg162Gly) a penetrating keratoplasty improved BCVA without any recurrence of the opacities within the follow-up time.

DISCUSSION

Different genotypes imply several phenotypes, which influence therapeutical proceedings in MCD patients. Our study shows the wide range of diagnostic findings and therapeutical options in patients suffering from macular corneal dystrophy depending on the genotype.

Histopathologic Study of Corneal Stromal Dystrophies

PURPOSE

To determine the frequency and describe the histopathologic features of stromal corneal dystrophies over a 10-year period.

METHODS

A single-centered, retrospective analysis was performed on corneal specimens diagnosed as stromal dystrophies retrieved from the Henry C. Witelson Ophthalmic Pathology Laboratory and Registry (Montreal, Canada) over a period of 10 years. Corneal specimens obtained during keratoplasty were subjected to hematoxylin and eosin, periodic acid-Schiff, and other special staining.

RESULTS

During the period of the study, 885 corneal specimens from penetrating keratoplasties were received. Twenty-six (2.9%) specimens from a total of 22 patients showed stromal corneal dystrophies: 17 (65.4%) eyes with lattice dystrophy, 5 (19.2%) eyes with combined granular/lattice ("Avellino") dystrophy, 3 (11.5%) eyes with granular dystrophy, and 1 (3.9%) eye with macular dystrophy.

CONCLUSIONS

Corneal stromal dystrophies have distinct histopathologic features, which can be diagnosed with routine and special staining, particularly for combined granular/lattice (Avellino) dystrophy. Clinically, combined granular/lattice (Avellino) dystrophy can have features of both lattice and granular dystrophies, which can be misleading for diagnosis. Lattice dystrophy was the most frequent stromal dystrophy in this particular population.

Corneal Transplant Survival after Onset of Severe Endothelial Rejection

PURPOSE

To evaluate corneal graft survival after onset of severe endothelial rejection after penetrating keratoplasty (PK).

DESIGN

Retrospective case series.

PARTICIPANTS

One hundred fifty-six patients (161 PKs) treated at a single center.

METHODS

Retrospective review of the medical records of every case of severe endothelial rejection admitted to the King Khaled Eye Specialist Hospital (KKESH) between January 1, 1998 and December 31, 2002. Patients for whom PK had been performed at KKESH between June 1, 1983 and December 31, 2002 and in whom at least 3 months of follow-up was available were included in the statistical analysis.

MAIN OUTCOME MEASURE

Graft survival.

RESULTS

One hundred fifty-seven PKs (152 patients) met the inclusion criteria and were included in the statistical analysis. Four PKs (4 patients) were excluded from the statistical analysis due to inadequate follow-up. The rejection episode was reversed during the first 3 months in 90 grafts (57.3%). By Kaplan-Meier analysis, graft survivals were 42.6% at 1 year and 36.1% at 3 years. The surgical indication for PK significantly correlated with likelihood of reversibility (P<0.001) and long-term graft survival (P<0.001). Risk factors associated with an increased risk of postrejection graft failure included increasing donor age (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.04-1.24; P = 0.004), increasing patient age (OR, 1.23; 95% CI, 1.11-1.35; P<0.001), and history of rejection episodes (P = 0.002).

CONCLUSION

Endothelial rejection is a serious complication of PK, with a high risk of graft failure.

Deep anterior lamellar keratoplasty by big-bubble technique for treatment corneal stromal opacities

PURPOSE

To evaluate the efficacy of using the big-bubble technique of deep anterior lamellar keratoplasty (DALK) for newer indications.

DESIGN

Prospective, noncomparative, interventional case series.

METHODS

Ten eyes of eight patients with pathologies involving the corneal stroma and sparing the Descemet membrane (DM) were included in this study conducted at a tertiary care hospital. The indications for DALK included corneal clouding attributable to mucopolysaccharidoses (n = 2), macular corneal dystrophy (n = 5), lattice corneal dystrophy (n = 1), granular corneal dystrophy (n = 1), and stromal scar attributable to infectious keratitis (n = 1). DALK was performed using the big-bubble technique in order to achieve the complete separation of DM from the corneal stromal tissue in the recipient's eye. Subsequently, the corneal stromal tissue was excised completely, and a full-thickness donor corneal lenticule without its DM was secured over the bared DM of the host. The main outcome measures of the study were the ability to successfully bare DM, the gain in visual acuity, and the presence of any complications.

RESULTS

Using the big-bubble technique, DM was bared, and DALK could be performed successfully in all eyes. No intraoperative or postoperative complications were observed. All patients achieved a best-corrected visual acuity (BCVA) of 20/40 or better at the end of six months.

CONCLUSIONS

DALK using the big-bubble technique can be useful in treating corneal stromal dystrophies, corneal clouding attributable to mucopolysaccharidoses, and stromal scar attributable to infectious keratitis.

Comparison of deep lamellar keratoplasty and penetrating keratoplasty for lattice and macular corneal dystrophies

PURPOSE

To compare the therapeutic outcomes after deep lamellar keratoplasty (DLKP) and penetrating keratoplasty (PKP) in patients with lattice corneal dystrophy (LCD) and macular corneal dystrophy (MCD).

DESIGN

Age-matched control study.

METHODS

We reviewed the clinical records of 84 eyes with LCD or MCD who had DLKP (41 eyes) or PKP (43 eyes). Primary pathology consisted of 60 eyes with LCD and 24 eyes with MCD. DLKP was performed by either removing stromal tissue gradually, or by viscodissection of Descemet's membrane. Graft clarity, best-corrected visual acuity (BCVA), endothelial density, and complications were compared between DLKP and PKP, as well as between LCD and MCD.

RESULTS

All 84 eyes showed a postoperative improvement in visual acuity. The median final BCVA was not significantly different between PKP and DLKP groups. Endothelial cell loss rates were similar for DLKP and PKP. While the MCD-DLKP group showed progressive decrease in endothelial density, this was not observed in the LCD-DLKP group after surgery. In the DLKP group, most of the complications occurred intraoperatively or in the early phase, whereas late phase complications such as endothelial rejection and secondary glaucoma were the main complications in the PKP group.

CONCLUSIONS

PKP is no longer an automatic choice for the surgical treatment for LCD and MCD; DLKP seems to be a safe alternative. While DLKP is a favorable method for LCD, MCD may not be a good candidate, as it might show progressive decrease in the corneal endothelium postoperatively.

Repeat penetrating keratoplasty: indications, graft survival, and visual outcome

AIM

To determine graft survival and visual outcome after repeat penetrating keratoplasty (PKP).

METHODS

Retrospective review of the medical records patients who underwent repeat PKP at the King Khaled Eye Specialist Hospital (KKESH) between 1 January 1991 and 31 December 2002.

RESULTS

243 repeat PKP performed in 210 eyes of 208 patients, who had also had initial PKP at KKESH, were included in the study. The mean follow up was 43 months (range 1-170). At the most recent examination, 114 (54.3%) grafts were clear. The overall survival rate was 98% at 1 year, 83% at 2 years, and 49% at 5 years. The best graft survival was in eyes with an original diagnosis of keratoconus (93.8%) and the worst was in eyes with Fuchs' dystrophy (23.1%). Overall, 29.6% of eyes achieved a final visual acuity greater than 20/200, while only 4.8% were 20/40 or better. The best visual prognosis was in eyes with an original diagnosis of stromal dystrophy and keratoconus.

CONCLUSION

Although the prognosis for repeat PKP is poorer than that of initial PKP, reasonable outcomes can be obtained with repeat PKP with careful case selection.