Recurrence of macular corneal dystrophy after lamellar keratoplasty

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.

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.

Recurrence of macular corneal dystrophy on the graft 50 years after penetrating keratoplasty

Purpose: To report the recurrence of a macular corneal stromal dystrophy 50 years after penetrating keratoplasty (PKP).

Methods: Observational case report

Casedescription: A 76-year-old male patient presented with visual impairment in the right eye (OD) 50 years after PKP in 1962 (44 years after PKP also in the left eye (OS) in 1968) following explosion injury. His visual acuity had already been impaired before the trauma because of bilateral corneal opacities. The central corneal thickness of the graft measured 584 µm (OD) and 544 µm (OS), whilst the peripheral host thickness (8 mm zone), however, was 1233 µm (OD, cranial) and 1131 µm (OS, nasal). The original graft diameter measured 6 mm in both eyes and the recipient cornea was cloudy and gray. The endothelial cell count was measured centrally (OD 1162 c/mm², OS 1320 c/mm²). The visual acuity was 20/100 (OD) and 20/40 (OS). After excimerlaser-assisted repeated PKP (8.0/8.1 mm, OD), the histological analysis of the former graft revealed deposits of acid mucopolysaccharides (AMP) subepithelially, within the interface, in the donor stroma, and in the endothelium, which proved the peripheral recurrence of a macular corneal stromal dystrophy on the graft.

Conclusion: Recurrence of macular corneal stromal dystrophy is seldom, but it may occur many decades after PKP. In this patient, the host’s stroma was twice as thick as that of the graft. This may be caused by the active production of acid mucopolysaccharides in the host endothelium with secondary endothelial decompensation. Thus, PKP remains the gold standard in the cure of macular corneal dystrophy for long-term visual rehabilitation.

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.

Macular Corneal Dystrophy and Posterior Corneal Abnormalities

PURPOSE

This study reports the presentation of 2 families with macular corneal dystrophy (MCD). The aim of this study was to show whether ultrasound biomicroscopy (UBM) can, based on posterior changes of the cornea in MCD, assist in the choice of surgery, either anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PK), compared with optical coherence tomography (OCT) and Scheimpflug.

METHODS

Six patients with MCD were examined for their best-corrected visual acuity, slit-lamp, OCT, UBM, and Scheimpflug findings. Blood samples for DNA and exons of the CHST6 gene were screened for mutations.

RESULTS

All 6 patients showed typical MCD signs at the slit lamp. Corneal transplantation was required in 2 patients in both eyes. Recurrence of MCD was observed in 2 eyes after the DALK procedure (patient A5, age 48 years, right eye and B1, 51 years, left eye), whereas the 2 eyes after PK (patient A5, age 48 years, left eye and patient B1, 51 years, right eye) remained clear (for 10 years of follow-up in patient A5 and 4 years in patient B1). In 2 patients (A1 and A3), corneal thinning could be evaluated by OCT. In 3 patients (A2, 3, and 4), UBM disclosed deeper pathologies including opacities, loss of continuity, and focal protrusions of the posterior cornea, which were not evident by other devices. In family A, a novel mutation was identified.

CONCLUSIONS

Our UBM examination of MCD shows alterations of the cornea's posterior layer and confirms the known clinical and histological findings of MCD that PK represents the therapy of choice, contrary to DALK. The novel CHST6 mutation shows the heterogeneity of MCD.

Recurrence of corneal stromal dystrophies after penetrating keratoplasty

PURPOSE

To assess the rates of simple and clinically significant recurrences of stromal dystrophies in corneal grafts.

METHODS

We conducted a retrospective review of Wills Eye Hospital records from 1984 to 2001, identifying all patients with stromal corneal dystrophies who had penetrating keratoplasties. Kaplan-Meier curves and chi analysis were performed.

RESULTS

The study population consisted of 35 eyes (21 patients) with lattice dystrophy, 17 eyes (10 patients) with corneal dystrophy of Bowman's membrane (CDB), 14 eyes (eight patients) with macular dystrophy, seven eyes (five patients) with granular dystrophy, and four eyes (four patients) diagnosed with Schnyder's crystalline dystrophy. There was a simple recurrence in 21 (60%) eyes (14 patients) with lattice and in 15 (88%) eyes (eight patients) with CDB. The median time to simple recurrence for the first eye transplanted of each patient was 8.4 years for lattice and 2.0 years for CDB. After 5 years of follow-up, there was a clinically significant recurrence, manifested by recurrent erosions or associated with decreased visual acuity, in the first eye transplanted of each patient, respectively, in six (17.1%) and seven (20%) eyes with lattice and in two (11.8%) and three (17.6%) eyes with CDB.

CONCLUSION

Corneal dystrophy of Bowman's membrane has the highest rate of simple recurrence followed by granular and lattice dystrophies, respectively. However, the rate of clinically significant recurrence, both recurrent erosions and decreased visual acuity, in the first 5 years is similar in CDB and lattice dystrophies. Recurrence is infrequent in macular and Schnyder's crystalline dystrophy. As expected, in genetic diseases, the potential for recurrence exists and increases with follow-up time.

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.

Recurrent macular corneal dystrophy following penetrating keratoplasty

The recurrence of macular corneal dystrophy within a corneal graft has been described in a number of case reports. In this study, we reviewed 41 transplants in 31 eyes of 16 patients undergoing keratoplasty for macular corneal dystrophy confirmed by histopathological examination. The follow-up time ranged between 25 and 408 months from initial diagnosis. Six eyes of four patients had repeat keratoplasty because of clinical recurrence and visual impairment. Pathological confirmation was available in five of the six eyes. Peripheral clinical recurrence was observed in two more eyes. The size of the graft used was inversely related to the recurrence.

Macular corneal dystrophy in Iceland

This study includes the fourteen Icelanders who had penetrating keratoplasty for macular corneal dystrophy during 1974 through 1988, and a further five patients whose deterioration of vision has so far not led to surgery. The clinical presentation, mode of inheritance and the course of the disease were similar to those seen in other studies. The genealogical part of this study indicates that the gene responsible for the disease was already present in Iceland in the 18th century. Though consanguinity, as usually defined, was found to be uncommon, the relatively small pool of genes in the Icelandic population which numbers at present about 250,000 has led to higher prevalence of macular corneal dystrophy than elsewhere. The histopathological findings concur with the conventional description of macular corneal dystrophy, with the exception of two patients with unusually severe photophobia. In these two cases, electron microscopy revealed that the most anteriorly situated deposits were sometimes associated with increased electron-density of small clusters of basal epithelial cells in the overlying epithelium, such cells also being reduced in size and exhibiting few organelles other than swollen mitochondria.

Congenital corneal opacification secondary to Bowman's layer dysgenesis

Progressive, bilateral corneal clouding was noted at birth in an otherwise healthy infant. There was no evidence of an infectious or hereditary cause. A trial of corticosteroids was unsuccessful, and the opacification in both corneas increased during the course of a few months, necessitating penetrating keratoplasty. However, reopacification of both grafts ensued within two to four months, and a second graft was done on the right eye. Histologic examination of both the original corneal buttons and the failed graft from the right eye showed a thickening of Bowman's layer that was three to four times greater than that of normal controls. This was associated with an increased number of keratocytes producing pools of collagen bundles within Bowman's layer. This report documents a unique form of corneal opacification unassociated with other ocular or systemic diseases. This process may be interpreted as a phenomenon in which the cells that contribute to the intrauterine formation of Bowman's layer continue to proliferate in an abnormal and exuberant fashion beyond fetal life, leading to corneal opacification.

Recurrence of macular corneal dystrophy within grafts

Two patients (a 41-year-old woman and a 40-year-old man) with macular corneal dystrophy developed significant visual impairment from recurrent disease within corneal grafts. One patient required regrafting 18 years after a penetrating keratoplasty, and the second patient underwent a penetrating graft 19 years after a lamellar corneal graft. In both cases the typical histochemical and electron-microscopic features of macular dystrophy were evident within donor tissue from the original grafts. The patient who originally underwent penetrating keratoplasty had recurrent disease in the corneal endothelium and within Descemet's membrane. Although the explanation of this observation is uncertain, endothelial cells of the recipient human cornea may resurface Descemet's membrane after penetrating keratoplasty, contrary to current belief. An alternative possibility is that involvement of both the corneal endothelium and Descemet's membrane in macular dystrophy is a secondary phenomenon, and that the abnormal storage product of this dystrophy is an abnormal metabolite rather than a normal compound with a defective catabolic enzyme as previously suspected.

Corneal dystrophies. I. Dystrophies of the epithelium, Bowman's layer and stroma

Most corneal dystrophies are autosomal dominant, bilateral disorders that primarily affect one layer of an otherwise normal cornea, progress slowly after their appearance in the first or second decade, and are not associated with a systemic disease. Epithelial basement membrane dystrophy and Fuchs' endothelial dystrophy are seen commonly by the general ophthalmologist; fleck, posterior polymorphous, granular or lattice dystrophies are seen more rarely, and others may never be seen in general office practice. While the distinctive clinical appearance of most corneal dystrophies allows accurate diagnosis, the integration of slitlamp findings with histopathologic and biochemical findings aids in the understanding of the clinical observations and provides a more rational basis for therapy. Transmission electtron microscopy is the most accurate method of histopathologic diagnosis. Epithelial dystrophies usually manifest intraepithelial cysts and abnormal basement membrane. In stromal dystrophies, an abnormal substance accumulates within the keratocytes or among the collagen fibrils; it may be an excess normal metabolite (like glycosaminoglycans in macular dystrophy), a material not usually present (like amyloid in lattice dystrophy), or a substance of unknown composition (like hyaline in granular dystrophy). Each dystrophy is illustrated with a composite drawing. Endothelial dystrophies will be reviewed separately in a second article.