Dystrophic changes in the anterior cornea

Efficacy of a Topical Heparan Sulfate Mimetic Polymer on Ocular Surface Discomfort in Patients with Cogan's Epithelial Basement Membrane Dystrophy

Purpose: Treatment of persistent ocular discomfort in patients with Cogan's epithelial basement membrane dystrophy (EBMD) is a challenge for ophthalmologists. This study aimed to determine the efficacy of a topical heparan sulfate mimetic polymer (HSMP) in reducing ocular discomfort in EBMD patients. Methods: This retrospective, noninterventional study included 22 consecutive patients in 3 tertiary ophthalmological units with spontaneous, recurrent, acute ocular pain, resistant to various topical lubricants. After EBMD diagnosis, HSMP treatment was initiated while lubricating eye drops were continued. The main study outcome was the change in ocular discomfort assessed using the ocular surface disease index (OSDI) from initiation of treatment to last follow-up visit. Results: The mean OSDI decreased from 46.7 ± 22.3 to 31.6 ± 17.4 (P < 0.001) at first visit and 32.5 ± 17.9 (P < 0.01) at last visit. The rate of patients with severe ocular surface disease (OSDI >33) decreased from 68.2% to 36.4% at first visit and 42.9% at last visit. After a median follow-up of 8.5 months, 7 (31.8%) patients discontinued the HSMP treatment due to a marked improvement in ocular surface comfort and no recurrence of ocular pain, 5 (22.7%) due to lack of efficacy, and 1 (4.5%) due to an ocular adverse event (not treatment related). Eight patients continued treatment after the last visit and 1 patient was lost to follow-up. Globally, HSMP prevented acute painful episodes in 11 (61.1%) of 18 patients followed for ∼4 months. Conclusions: Topical HSMP may be an option for alleviating ocular discomfort in patients with EBMD resistant to standard symptomatic treatments.

Recurrent corneal erosion syndrome

Recurrent corneal erosion syndrome (RCES) is a disorder characterised by a dysfunctional epithelial ecosystem. It often begins after trauma, or in the setting of epithelial basement membrane degeneration or dystrophy. Historically, RCES has been understood as a structural derangement of the anterior corneal architecture. More recently, studies have demonstrated the important role of neuropeptides in corneal homoeostasis. Thus, RCES may also be understood as a disorder of corneal epithelial cell biology. Management of RCES can be challenging, but newer therapies have demonstrated improved efficacy for this condition. This review examines the aetiology and pathogenesis of RCES, and provides an update on current and emerging treatment modalities for the management of this disorder.

Recurrent corneal erosions and epithelial basement membrane dystrophy

Epithelial basement membrane dystrophy, the most common hereditary anterior corneal dystrophy and considered a "category 1" dystrophy in some cases, encompasses microcystic dystrophy and other conditions affecting the epithelial basement membrane. The management of symptomatic epithelial basement membrane dystrophy includes alleviating blurred vision, treating recurrent corneal erosion, or both. Treatment of distorted vision may be as simple as prescribing lubricating drops and/or ointment, and posttrauma corneal erosion is often a limited problem that disappears over time and does not require laser or surgical treatment. This article describes treatment for more severe cases of corneal erosion, which includes mechanical debridement of the loosened epithelium.

In vivo laser confocal microscopic findings in patients with epithelial basement membrane dystrophy

PURPOSE

To evaluate the corneal characteristics of patients with epithelial basement membrane dystrophy (EBMD) using an in vivo laser confocal microscope, Heidelberg Retina Tomograph II, Rostock Cornea Module (HRT II RCM).

METHODS

Sixteen women and 13 men who were diagnosed with or suspected to have EBMD were included in the study. The mean age of the patients was 56.4+/-17.2 years within a range of 25 to 81 years. Nine patients (31%) had a history of recurrent corneal erosions and 3 patients had been misdiagnosed with herpetic epithelial keratitis. The remaining 17 patients were asymptomatic and EBMD was diagnosed incidentally during routine eye examinations.

RESULTS

Confocal microscopy revealed highly reflective tissue in various configurations within the intermediate and basal epithelial cell layers corresponding to the abnormal basement membrane extending into the epithelium. There were thin, parallel hyperreflective lines and high contrast round lesions in sizes ranging between 10 and 250 microm within the epithelium. Basal epithelial cells around the abnormal basement membrane and cysts seemed to be highly distorted. In two subjects with bleb-like disorder, the authors observed circular or oval hyporeflective areas with a diameter ranging between 40 and 100 microm at the level of basal epithelium and the Bowman layer, accompanied by hyperreflective, linear structures extending into the epithelium.

CONCLUSIONS

EBMD is most commonly asymptomatic and undiagnosed; however, it might be associated with recurrent corneal erosions and lead to severe complications after LASIK surgery. The confocal images are highly characteristic for EBMD; therefore, confocal microscopy seems to be a valuable tool in the diagnosis of EBMD.

Epithelial debridement for the treatment of epithelial basement membrane abnormalities coincident with endothelial disorders

PURPOSE

To determine if treatment directed at the epithelial basement membrane abnormalities in eyes with endothelial disorder can improve visual acuity and surface irregularity.

METHODS

Retrospective interventional case series of 4 eyes of 3 patients with epithelial basement membrane abnormalities and endothelial disorder coincident with Fuchs endothelial corneal dystrophy or iridocorneal endothelial syndrome that had initial treatment directed only at the epithelial basement membrane disorder.

RESULTS

In 2 of the 4 eyes undergoing epithelial basement membrane debridement, visual acuity improved by 3 Snellen lines. In the other 2 eyes, the intervention improved visual acuity by 2 lines in 1 eye and no lines in the other, but the procedure allowed for accurate keratometry readings to be obtained for intraocular lens calculations before cataract surgery.

CONCLUSIONS

Epithelial basement membrane abnormalities can occur in eyes with endothelial disorder. Treatment of the epithelial basement membrane disorder in these eyes can sometimes improve the regularity of the ocular surface and visual acuity.

Amoils epithelial scrubber to treat recurrent corneal erosions

PURPOSE

To evaluate the treatment of recalcitrant recurrent corneal erosions (RCE) with superficial keratectomy using the Amoils epithelial scrubber (AES).

SETTING

Muncie Eye Center, Muncie, Indiana, USA.

METHODS

This study was a retrospective consecutive case series comprising 23 patients (26 eyes) who had superficial keratectomy for RCE using the AES between September 1997 and May 2003 at a private tertiary-care center. The preoperative and postoperative best corrected visual acuities (BCVAs), slitlamp findings, and postoperative incidence of RCE were studied.

RESULTS

During a mean telephone survey follow-up of 21.2 months +/- 20.5 (SD) (range 1.4 to 71.3 months), 20 patients (23 eyes, 88%) reported no further RCE symptoms. The BCVA improved or stayed the same in 25 eyes (96%). No significant complications were found.

CONCLUSION

Superficial keratectomy using the AES appears to be safe and effective for treating recalcitrant RCE.

Diamond burr superficial keratectomy for recurrent corneal erosions

AIMS

To evaluate the efficacy and safety of diamond burr superficial keratectomy in the treatment of recurrent corneal erosions.

METHODS

A retrospective review of 54 eyes (47 patients) with recurrent corneal erosions treated with diamond burr superficial keratectomy. Preoperative and postoperative visual acuities and refractions, slit lamp examination findings, and the incidence of recurrent erosion after keratectomy were studied. Specular microscopy was also performed in six patients before and after surgery.

RESULTS

30 eyes had underlying map dot fingerprint anterior basement membrane corneal dystrophy, while 24 eyes did not. Postoperative follow up time ranged from 3 to 53 months (mean 12.3 months). Corneal erosion recurred in three eyes (6%) after diamond burr superficial keratectomy. This procedure improved the best corrected visual acuity from 20/26 to 20/22 by logMAR statistical evaluation (p=0.002) and caused very little change in the refractive spherical equivalent. No endothelial cell loss or changes in morphology were noted on specular microscopy.

CONCLUSION

Diamond burr superficial keratectomy appears to be an effective and safe method of treating recurrent erosions and is a good alternative therapy to needle stromal micropuncture, Nd:YAG induced epithelial adhesion, and excimer laser surface ablation.

BIGH3 gene mutations and rapid detection in Korean patients with corneal dystrophy

PURPOSE

Mutations in the BIGH3 gene on chromosome 5q31 cause four distinct autosomal dominant corneal dystrophies. We sought to determine whether the BIGH3 gene mutation was responsible for corneal dystrophy in Korean patients.

METHODS

Polymerase chain reaction single strand conformational polymorphism (PCR-SSCP) analysis was performed with the DNA from patients and healthy individuals. We sequenced the PCR products with the aberrant SSCP pattern to identify the mutation. Mutant-specific reverse primers were used to screen genomic DNA for the identified mutations.

RESULTS

We identified mutations R124C in the CDL1 family and R124H in four families with a granular dystrophy. We identified our granular dystrophy to be Avellino corneal dystrophy (ACD). Eighteen of 20 patients with a granular dystrophy contained the same R124H mutation, indicating that mutation R124H was very common in Korean patients with ACD. During this study, we identified a new polymorphism (T1667C, F540F).

CONCLUSIONS

This is the first report of mutations found in the BIGH3 gene in Korean families with corneal dystrophy. We report that the majority (90%) of ACD patients in Korea carry the R124H mutation. Mutant-specific reverse primers can be used to screen efficiently for CDL1 and ACD.

Phototherapeutic keratectomy for recurrent corneal erosions

Recurrent corneal erosion may be a difficult disorder to treat, with a number of patients suffering persistent symptoms despite conventional therapy. We present a series of 15 patients (17 eyes) who underwent excimer laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion. In 9 patients a previous episode of corneal trauma could be identified, while in 6 (8 eyes) the problem had occurred spontaneously. The mean duration of symptoms prior to PTK was 13 months (range 6-60 months). All patients had received lubricant ointments, 7 had tried bandage contact lenses and 4 had undergone epithelial debridement with no amelioration of their symptoms. The affect area of epithelium was removed and a 20-30 pulse (5-7 microns) ablation was performed to Bowman's membrane. Great care was taken to avoid the edges of treatment zones from encroaching on the axial cornea. In 11 patients (13 eyes) there was a marked improvement in symptoms post-operatively with no recurrences. The mean follow-up was 11 months (range 6-24 months). Four patients experienced recurrent episodes 3-6 months after PTK and 2 have subsequently been retreated, 1 of whom has been symptom-free for 12 months. Post-operative best corrected visual acuity was unaltered in 9 eyes and improved by at least one Snellen line in 8 eyes. Excimer laser PTK appears to be a safe and promising procedure for recurrent corneal erosion in cases refractory to medical treatment. Further studies are indicated to compare its effectiveness with established surgical procedures.

Oral tetracycline in the treatment of recurrent corneal erosions

We report the results of a prospective, randomised controlled, 24 week trial to assess the efficacy of oral tetracycline and oral tetracycline with topical prednisolone in the treatment of recalcitrant recurrent corneal erosions, i.e. those which fail to respond to standard therapy. A total of 30 patients were randomly allocated to either standard treatment (group A), standard treatment and oral tetracycline (group B) or standard treatment, oral tetracycline and topical prednisolone (group C). Treatment groups B and C were instructed to perform daily lid hygiene. There was a significant reduction in the number of recurrent corneal erosions during the 24 week study period in group B (p = 0.04) and in group C (p = 0.0003) but not in group A (p = 0.66). There was a significant difference in the accelerated healing time of recurrent corneal microerosions between groups A and B (p = 0.001) and between groups A and C (p = 0.001). There was a significant improvement in the symptom scores during the study in treatment groups B and C (p = 0.005) but not in group A (p = 0.15). We conclude that lid hygiene and oral oxytetracycline 250 mg twice daily for 12 weeks with or without topical prednisolone for the first 7 days is beneficial in the management of recalcitrant recurrent corneal erosions.

Anterior corneal dystrophy of American Dutch belted rabbits: biomicroscopic and histopathologic findings

Spontaneously occurring anterior corneal opacities were present in related, juvenile American Dutch belted rabbits. Slit lamp biomicroscopy revealed focal opacities of epithelium, basement membrane, and subepithelial corneal stroma. Lesions were characterized histologically by thin and disorganized surface epithelium, thickened and intensely staining epithelial basement membrane, fimbriated and irregular basement membrane-stromal juncture, and disorganized subepithelial stroma. Biomicroscopic and histopathologic features of anterior corneal dystrophy of American Dutch belted rabbits appear similar to those of human anterior corneal dystrophies.

Electron microscopy of corneal surface microdiathermy

Microdiathermy has recently been shown to be effective in the treatment of persistent corneal epithelial recurrent erosion. In order to determine the mechanism of action of microdiathermy on the anterior surface of the cornea, rabbit eyes were treated with microdiathermy and the course of corneal tissue repair studied by electron microscopy. Shortly after treatment, the epithelium is edematous and necrotic and the lamina densa is thickened. Within 24 hours, the epithelium appears healed and some hemidesmosomes are present, but the lamina densa is still thickened. At two weeks the epithelial surface is undulated and protrudes into the stroma in areas where the lamina densa is disrupted. Hemidesmosomes are absent in these regions. Activated fibroblasts are present in superficial stroma. At four weeks following microdiathermy, there is segmental deposition of new lamina densa and a connective tissue zone between the newly deposited lamina densa and the old lamina densa. Hemidesmosomes are present only in areas of newly deposited lamina densa. Between six weeks and three months the epithelial basal surface becomes more uniform with mature hemidesmosomes and the new lamina densa is complete. The old lamina densa remains below it but is no longer present by six months. The mechanism of action for microdiathermy in recurrent erosion is believed to be as follows: in the treated area, epithelium and activated fibroblasts secrete a new connective tissue layer, which provides a suitable substrate to which the epithelium can adhere until it secretes a new lamina densa and hemidesmosome formation can occur.

Stromal keratitis complicating anterior membrane dystrophy

Recurrent erosion of the cornea has been well documented in patients with nontraumatic anterior membrane dystrophies of various types. We examined five patients who, in addition to an erosion, developed stromal keratitis. Three of these patients were subjected to a complete microbiologic workup, but the lesions were all sterile. The lesions healed with conservative treatment of patching and, in some cases, a soft contact lens. Stromal keratitis should be recognized as a complication of the non-traumatic recurrent erosion syndrome, which in turn is frequently associated with anterior membrane dystrophy. The finding of such anterior membrane changes in either eye will lead to the correct diagnosis and treatment of the affected eye.

Pathogenesis and treatment of recurrent erosion

A series of recurrent corneal erosions secondary to map-dot-fingerprint dystrophy is presented. Erosions were closely related to the Hudson-Stahli line, and this may be a factor in pathogenesis. Traumatic abrasions did not demonstrate such localisation, evidence that trauma is not a primary cause. A trial of management with therapeutic contact lenses versus topical medication was performed. Therapeutic contact lenses were shown to be inferior and had a high complication rate. Recurrent erosion is often considered an indication for therapeutic contact lenses, but this is questioned and great caution recommended in such use.

Anterior membrane dystrophy following cataract extraction

This paper describes a patient with previously normal corneas who underwent bilateral cataract surgery. This was followed by acute dehiscence of the epithelium and the eventual appearance of fingerprint lines, microcysts, and map-like areas typical of Cogan's microcystic dystrophy. Light and electron microscopy showed the presence of epithelial microcysts and a seam of subepithelial material like basement membrane. It is suggested that this patient represents a rapid transition from apparent normality to an extensive anterior membrane dystrophy, precipitated by operation for cataract.

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.

Contributions of electron microscopy to the study of corneal pathology

Most of the electron microscopic studies of pathological corneas have been done only recently. Keratoplasty has been the most important source of specimens for ultramicroscopic investigation. With the introduction of electron microscopic techniques, we have been able to confirm many light microscopic studies in pathological corneas. This contribution has been most valuable in the identification of the sites and types of pathological changes in corneal dystrophies and degenerations. This review of electron microscopic studies describes the present concepts on the nature of the histological changes in dystrophies and degenerations of the anterior and posterior corneal layers and corneal stroma. It also includes a review of some corneal inflammatory conditions as well as metabolic disorders affecting its transparency.

Recurrent erosion of the cornea

Altogether, 80 patients aged between 24 and 73 years with recurrent erosion of the cornea have been studied and compared with a control group of 200. The patients' erosions were divisible into macroform and microform types. The macroform occurred in 10%, the microform in 56%, and both types in the same patients in 31%. The macroform was more commonly related to trauma than the microform. However, many (40%) were spontaneous in origin. The most common cause of the initial trauma was a finger nail. The recurrences occurred at around the time of waking, either just before or just after. Difficulty in opening the eye occurred in 10%. There was little evidence of precipitating factors, but eye rubbing was admitted by 10% and barbiturates were implicated in 3%. The corneae were examined in the healed state, when a high incidence (59%) were found to have superficial corneal dystrophies of the fingerprint lines, bleb, and Bietti's lacunar (map-like) types. These are considered individually, particular attention being paid to the distinction between the various types of line resembling the fingerprint line. Epithelial microcysts were also a common finding (59%) and were sometimes of the Cogan type. In only 11% of patients were there no corneal signs in the healed state. The need for careful examination of the cornea by retroillumination, using both the iris and the fundus, is stressed. The control group, in contrast, showed a very low incidence of dystrophies and cysts. Treatment was given initially with either drops or ointment and no differences in healing were found. Debridement was performed in 12 eyes as an initial treatment and also in four eyes which were not healing on medical treatment. Debridement assisted healing, but did not prevent recurrence. One eye was treated with debridement and scarification and seven with carbolization. These procedures appeared to reduce the recurrence rate. Sodium chloride ointment 5% was found useful as a prophylactic taken at bedtime, and the recurrence rate increased when it was withdrawn.

Superficial lines and associated disorders of the cornea

In a clinical classification of fine superficial corneal lines, we recognized five major types of line: mare's tail lines, fibrillary lines, fingerprint lines, lacunar dystrophy or map-like changes, and tram lines. The fingerprint lines were further classified into several subgroups. There was a relationship between certain lines, in particular, fingerprint lines and lacunar dystrophy or map-like change with the occurrence of Cogan's microcystic dystrophy and recurrent erosion.

Defective epithelial adhesion in anterior corneal dystrophies

Experimental and pathologic studies implicated the role of the epithelial basement membrane and its associated hemidesmosomes and anchoring fibrils in mediating tight adhesion between corneal epithelium and stroma. We evaluated the ultrastructural quality of basement membrane complexes in patients with Reis-Bücklers dystrophy, Cogan's microcystic dystrophy, and nontraumatic recurrent erosion who presented with clinically significant erosive symptoms. Despite the variable clinical and histopathologic appearances among these dystrophies, incompleteness of basement membrane complexes apparently was a common fault shared by these erosive disorders. Such basic incompetence at the basement membrane level can both provoke and sustain erosions, while the more individual pathologic manifestations of a given anterior dystrophy may be of less primary significance.

Cystic disorders of the corneal epithelium. I. Clinical aspects

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Cystic disorders of the corneal epithelium. II. Pathogenesis

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