Recurrent macular corneal dystrophy type II 49 years after penetrating keratoplasty

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.

Phototherapeutic keratectomy

Phototherapeutic keratectomy is an excimer laser-based surgical procedure widely performed by corneal surgeons for treating anterior corneal stromal pathologies. Phototherapeutic keratectomy helps by ablating the corneal stroma, thereby improving corneal clarity and smoothening the surface. Transient discomfort and induced hyperopia from corneal flattening are the immediate postoperative concerns. The long-term course is often marked by the recurrence of original corneal pathology and corneal haze formation. Phototherapeutic keratectomy, however, allows for repeat stromal ablation for managing recurrences, as the corneal thickness permits, without affecting the outcome of future keratoplasty. Adjunctive methods such as topical mitomycin-C may be additionally used to reduce recurrence rates. Also, various masking agents such as carboxymethyl cellulose, sodium hyaluronate, and dextran are used in eyes with irregular corneal surface to allow for uniform stromal ablation. Overall, phototherapeutic keratectomy has provided corneal surgeons an additional surgical tool, particularly those residing in developing nations where the availability of donor corneal tissue is an important limiting factor.

Collagen Fibrils and Proteoglycans of Macular Dystrophy Cornea: Ultrastructure and 3D Transmission Electron Tomography

We report the ultrastructure and 3D transmission electron tomography of collagen fibrils (CFs), proteoglycans (PGs), and microfibrils within the CF of corneas of patients with macular corneal dystrophy (MCD). Three normal corneas and three MCD corneas from three Saudi patients (aged 25, 31, and 49 years, respectively) were used for this study. The corneas were processed for light and electron microscopy studies. 3D images were composed from a set of 120 ultrastructural images using the program "Composer" and visualized using the program "Visuliser Kai". 3D image analysis of MCD cornea showed a clear organization of PGs around the CF at very high magnification and degeneration of the microfibrils within the CF. Within the MCD cornea, the PG area in the anterior stroma was significantly larger than in the middle and posterior stroma. The PG area in the MCD cornea was significantly larger compared with the PG area in the normal cornea. The CF diameter and inter-fibrillar spacing of the MCD cornea were significantly smaller compared with those of the normal cornea. Ultrastructural 3D imaging showed that the production of unsulfated keratin sulfate (KS) may lead to the degeneration of micro-CFs within the CFs. The effect of the unsulfated KS was higher in the anterior stroma compared with the posterior stroma.

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.

Long-term results of phototherapeutic keratectomy with 193-nm excimer laser for macular corneal dystrophy

PURPOSE

To investigate functional and morphologic long-term outcome of phototherapeutic keratectomy (PTK) in macular corneal dystrophy.

DESIGN

Retrospective, clinical single-center study.

METHODS

Between October 1990 and February 2004, 10 eyes (five oculus dexter, five oculus sinister) of 6 patients (mean age, 23 +/- 8 years [range, 15 to 37 years]) with superficial plaque-like opacities that were caused by macular corneal dystrophy were included. After epithelial debridement and pannus removal, PTK was performed with the 193 nm MEL 60 excimer laser. Intended laser ablation depth varied from 20 to 100 microm; the repetition rate was 20/s or 25/s, and the pulse number was 1774 +/- 502 (range, 976 to 2422). Mean follow-up was 4.5 +/- 3.1 years [maximum, 8.7 years]). Main outcome measures included: uncorrected visual acuity, best corrected visual acuity (BCVA), spherical equivalent, keratometric central power, keratometric astigmatism and regularity (semiquantitative classification of Zeiss keratometry; scale 0 to 3), postoperative "haze," time interval until complete epithelial closure, recurrence rate, and necessity of subsequent penetrating keratoplasty (PK).

RESULTS

BCVA increased from 0.3 +/- 0.2 before the operation to 0.6 +/- 0.1 after the operation; the mean spherical equivalent increased from -0.9 +/- 1.1 diopters to -0.4 +/- 1.8 diopters. Mean keratometric central power decreased from 44.5 +/- 0.7 diopters to 42.5 +/- 0.6 diopters. During follow-up, recurrences occurred in nine eyes (90%) after 3.4 +/- 0.4 years. In six eyes, a PK was performed after an average of 5.0 years (range, 3.7 to 6.7 years). None of the transplants had a recurrence during the follow-up period.

CONCLUSION

In superficial opacities that are caused by macular corneal dystrophy, PTK can increase BCVA moderately for a limited period of time. Despite possible complications, primary PK still appears to be the definite therapeutic option for patients with macular corneal dystrophy.

Recurrence of chromosome 10 Thiel-Behnke corneal dystrophy (CDB2) after excimer laser phototherapeutic keratectomy or penetrating keratoplasty

PURPOSE

To evaluate the recurrence of Thiel-Behnke dystrophy (linked to the 10 q23-q24 locus) after phototherapeutic keratectomy or penetrating keratoplasty.

METHODS

This is a retrospective study of 4 patients (8 eyes) who underwent phototherapeutic keratectomy and 1 patient (2 eyes) who underwent penetrating keratoplasty. Best corrected visual acuity was assessed, and biomicroscopic examinations for evidence of recurrent dystrophy were documented and photographed. The location, lesion distribution, and lesion pattern of any recurrence was noted.

RESULTS

Follow-up ranged from 8 months to 25 years (mean +/- SD 9.7 +/- 7.97 years). All 10 eyes showed biomicroscopic evidence of central recurrence. Six eyes showed an intermediate zone of honeycomb opacities as well as a peripheral zone of focal and geographic lesions. Despite the high incidence of recurrence, functional central visual acuity was maintained. All eyes maintained functional best corrected visual acuity (ranging from 20/25 to 20/80) despite the postoperative recurrence.

CONCLUSION

Recurrence of Thiel-Behnke corneal dystrophy is extremely high after either phototherapeutic keratectomy or penetrating keratoplasty. Despite the high incidence of recurrence, the central cornea is the last to be affected. The peripheral-to-central progression of the lesions points to an epithelial origin for the pathogenesis of the dystrophy. Phototherapeutic keratectomy in the treatment of Thiel-Behnke corneal dystrophy offers a safe and effective treatment modality, providing patients up to 8 years of improved vision ranging from 8 months to 8 years (mean +/- SD 3.7 +/- 2.7 years) and delaying or circumventing the need for more invasive intraocular surgical intervention.

Penetrating keratoplasty for macular corneal dystrophy

PURPOSE

To determine the prognosis of penetrating keratoplasty (PK) for macular corneal dystrophy (MCD).

DESIGN

Single-center, retrospective, interventional, noncomparative case series.

PARTICIPANTS

One hundred forty-one patients (229 eyes) with MCD.

INTERVENTION

Retrospective review of the medical record of every patient who underwent primary PK for histopathologically confirmed MCD at the King Khaled Eye Specialist Hospital between January 1, 1983 and December 31, 2002 and for whom at least 12 months of follow-up is available.

MAIN OUTCOME MEASURES

Visual acuity (VA), graft survival, and postoperative complications.

RESULTS

After a mean follow-up period of 5.9+/-3.8 years (range, 1-17), the mean best-corrected VA was 20/50. At the most recent visit, 206 (90.0%) grafts were clear, and 23 (10.0%) had failed. Probabilities of graft survival were 98.1% at 1 year, 89.8% at 5 years, 82.1% at 10 years, and 74.1% at 15 years. There was a statistically significant increased likelihood of graft failure if the patient was older than 40 years at the time of surgery (P<0.00003). The differences in graft failure between patients older than 40 and those younger were not attributable to statistically significant differences in duration of follow-up, donor age, or donor endothelial cell counts. Corneal endothelial rejection episodes occurred in 47 (20.0%) grafts, but resulted in irreversible graft failure in only 8 (3.5%) eyes. Eighteen (27.3%) of 66 eyes with a recipient size of > or =7.5 mm developed a graft rejection episode, compared with 27 (16.6%) of 163 eyes with a recipient size of <7.5 mm (P = 0.04). Microbial keratitis occurred in 14 (6.1%) grafts and was more likely to occur in patients over 40 (14.0% vs. 3.0%, P = 0.01). Clinically significant recurrence was observed in 12 (5.2%) grafts, after a mean interval of 84+/-48.2 months, and was directly related to patient age (P = 0.04) and inversely related to donor graft size (P = 0.04).

CONCLUSIONS

Good visual results and excellent graft survival can be achieved after PK for MCD. The risk of graft failure is higher in patients older than 40 years.

Immunohistochemical classification of primary and recurrent macular corneal dystrophy in Germany: subclassification of immunophenotype I A using a novel keratan sulfate antibody

Macular corneal dystrophy (MCD) is an autosomal recessive disease characterized by abnormal deposition of glycosaminoglycans in corneal stroma, keratocytes, Descemet's membrane and corneal endothelium. According to the presence and distribution of sulfated keratan sulfate (KS)-epitopes in serum and cornea (using mAb 5-D-4), MCD can be classified into three immunophenotypes: type I, I A and II. The purpose of this study is to evaluate the immunophenotype of primary and recurrent MCD and to analyze the reactions of a novel KS-antibody in MCD corneas, which recognizes an epitope localized in the binding region of KS-chains to the core protein (mAb 3D12/H7). Indirect immunohistochemistry for KS (mAbs 3D12/H7 and 5-D-4) was performed on 44 corneas of 37 patients with MCD including two recurrences. Immunogold labeling was used to localize KS ultrastructurally within keratocytes. The serum concentration of KS (cKS) was determined in a serum antigen-inhibition assay. Immunohistochemically, no reaction was observed using mAb 5-D-4 in 18 corneas of 16 patients (43% of 37 patients; immunophenotype I). Positive reactions within single keratocytes but not in the stroma, were seen in 22 corneas of 17 patients (46% of 37 patients; immunophenotype I A) and positive reactions in keratocytes and extracellular stroma were found in four corneas of four patients (11% of 37 patients: immunophenotype II). For analysis of cKS a total of seven samples was available. Whereas in the samples of the five patients with immunophenotypes I and I A cKS was below the limit of detection, in the two sera from patients with immunophenotype II, cKS was normal (cKS = 1243 and 1380 nmol l(-1)). The two recurrences demonstrated immunophenotype II. Using mAb 3D12/H7, MCD immunophenotype I A can be further subclassified in type I A 1 (lacking reaction with mAb 3D12/H7 in keratocytes; 77%) and type I A 2 (positive reaction with mAb 3D12/H7 within keratocytes; 23%). MCD immunophenotype I A can not only be found in Saudi Arabia, but is as common as immunophenotype I in German patients. The only recurrences of MCD necessitating regrafting occurred in two patients with immunophenotype II possibly suggesting a higher risk for recurrence in this immunophenotype. The mAb 3D12/H7 allows a further subclassification of immunophenotype I A into type I A1 and 2. This points to a broader spectrum of MCD immunophenotypes and indirectly to a broader corneal proteoglycan pathology in MCD.

Genetics of the corneal dystrophies: what we have learned in the past twenty-five years

PURPOSE

To indicate important changes in our understanding of the corneal dystrophies.

METHODS

A review of the literature of the last quarter of a century.

RESULTS

The earliest clinical classifications of the corneal dystrophies were based on the application of clinical, biological, histochemical, and ultrastructural methods. Since then, the first great impetus to our understanding has come from the application of techniques to map disorders to specific chromosome loci, using polymorphic markers. More recently, using candidate gene and related approaches, it has been possible to identify genes causing several of the corneal dystrophies and the mutations responsible for their phenotypic variation. A notable success has been to show that several important "stromal" dystrophies result from mutations in the gene beta ig-h3, which encodes for the protein keratoepithelin (beta ig-h3).

CONCLUSIONS

For the corneal dystrophies, as with other inherited disorders, there is room for two sorts of classification system, one based mainly on clinical presentation and the other on an up-to-date understanding of the genetic mechanisms. They are not mutually exclusive. Some developmental corneal disorders are also discussed.