Clinicopathological correlation of congenital corneal opacification using ultrasound biomicroscopy.

AIM: To investigate the correlation between clinical, high frequency ultrasound biomicroscopy (UBM) and, where possible, histological findings in cases of congenital corneal opacification presenting to the departments of ophthalmology, Great Ormond Street Hospital for Children, London, and the Hospital for Sick Children, Toronto, Canada. METHOD: 22 eyes of 13 children (age range 3-225 days) with congenitally opaque corneas were examined. UBM was performed using the ultrasound biomicroscope (Allergan-Humphrey). All eyes underwent penetrating keratoplasties (PKP) except five. The host corneas were all sent for histological examination. RESULTS: The final diagnosis in our series was Peters' anomaly in nine cases (70%), corneal dystrophy in two cases (15%), and sclerocornea in two cases (15%). The UBM findings changed the clinical diagnosis in five cases (38%). In these five cases histology was available in four and confirmed the UBM diagnosis in each case. In no case of the 13 where histology was available did it contradict the UBM findings. In two cases a hypoechoic region in the anterior stroma was seen on UBM which correlated histologically with absent Bowman's layer and oedema. In two cases UBM revealed aniridia and in one, congenital aphakia, which was not apparent clinically. CONCLUSION: UBM examination is not only very useful in evaluating the clinical diagnosis in congenital corneal opacification, it also acts as a preoperative guide in cases undergoing PKP by detecting keratolenticular and iridocorneal adhesions and other ocular abnormalities such as aniridia and congenital aphakia. In all cases where PKP was performed the UBM diagnosis was confirmed histologically. The clinical diagnosis was incorrect in five cases. This has important implications in studies of phenotype/genotype correlation of congenital corneal opacification.     

Structural analysis of normal corneas and diseased corneas by applying second harmonic generation

We have established a second harmonic generation (SHG) microscopy system for imaging of the human cornea with a mode-locked femtosecond laser and a laser confocal microscope. This SHG microscopy system has allowed us to scan corneal tissue noninvasively ex vivo and to obtain three-dimensional images of corneal collagen lamellae. Such three-dimensional imaging of the normal anterior cornea revealed that collagen lamellae at the anterior stroma are inter-woven and adhere to Bowman membrane with these adherent lamellae being designated "sutural lamellae." Sutural lamellae adhere to Bowman membrane at an angle of approximately 19 degrees, whereas the angle of lamellae in the mid-stroma relative to Bowman membrane is smaller. We hypothesize that the structural unit consisting of both Bowman membrane and the sutural lamellae contributes to the rigidity and anterior curvature of the cornea. SHG imaging of keratoconic corneas revealed an either abnormal or a total lack of structure of the sutural lamellae, suggesting that this abnormality might be related to that of the corneal anterior curvature in such corneas. Furthermore, SHG imaging of corneas affected by stromal edema showed that the structure of the sutural lamellae was maintained, although abnormal collagen signals both above and below Bowman membrane were detected in corneas affected by clinical stromal edema for more than 12 months. SHG imaging of the structure of collagen lamellae in normal and diseased corneas thus has the potential to provide insight both into the mechanism for maintenance of corneal curvature as well as into the pathophysiology of corneal diseases.     

Mosaic Chromosome 18q Partial Deletion Syndrome with Bilateral Full-thickness Corneal Disease: Surgical Intervention and Histopathology

A 2-month-old boy diagnosed with a mosaic chromosome 18q partial deletion syndrome was referred for bilateral cloudy corneas. The abnormal metaphases had a terminal deletion of the long arm of chromosome 18 as clonal abnormality. The cytogenetics findings were 46,XY, del (18)(q21.2)[12]/46,XY[20]. Ocular findings included bilateral microcornea with dense opacification and unilateral iris and chorioretinal coloboma. Penetrating keratoplasty (PK) was performed on both eyes. Histopathology of the host corneal button showed complete loss of Bowman’s layer, hyperkeratosis of the epithelium, stromal neovascularization, and leukocyte infiltration. Descemet’s membrane and endothelium were irregular in both specimens. CD45 stain for leukocytes confirmed perivascular and epithelial leukocytes infiltration. Mosaic chromosome 18q deletion syndrome is a rare genetic abnormality with a variable phenotype – including ocular findings – and hence, warrants an ophthalmic evaluation and genetic counseling.     

Use of nerve growth factor to treat congenital neurotrophic corneal ulceration

PURPOSE: This study was designed to assess the efficacy of nerve growth factor in the treatment of neurotrophic corneal ulceration in a child with bilateral congenital corneal anesthesia secondary to trigeminal insufficiency. METHODS: A 5-month-old child presented to the casualty department with a 2-week history of red eyes and right corneal ulceration. Slit-lamp examination showed a central defect in the right corneal epithelium with underlying stromal opacification, only mild conjunctival inflammation with slight decreased tear production, and otherwise apparently normal eyes. Initially this was investigated as an infected ulcer and treated for several weeks as herpetic ulceration with no beneficial effect. Further clinical examination demonstrated bilateral decreased corneal sensation along with decreased facial sensation in keeping with congenital trigeminal nerve insufficiency. Investigation with magnetic resonance imaging showed no obvious abnormality. Conservative treatment with lubricants resulted in progressive right corneal stromal loss, and no healing occurred in the left corneal ulcer. Bilateral large lateral tarsorrhaphies were performed. Despite this, the left corneal ulcer demonstrated no improvement and increasing stromal opacification was noted. Topical nerve growth factor (NGF) was then used to treat the left cornea and resulted in epithelial healing within 1 week. Treatment was continued for a further 10 days after epithelial healing. Despite conventional treatment on 3 separate occasions, further epithelial breakdown occurred. Topical NGF treatment resulted in a rapid improvement and healing of the epithelial defect.'At present, the patient is receiving a 6-month continuous treatment plan of NGF. RESULTS: Persistent epithelial defects (PED) secondary to neurotrophic ulceration have responded to topical NGF on 3 separate occasions during a 2-year period. The corneal epithelium now remains intact, and the cornea has no vascularization; however, mild anterior stromal opacification has gradually increased despite prolonged NGF treatment. CONCLUSION: NGF seems to represent a safe and efficacious treatment option to restore the integrity of corneal epithelium in which there is congenital corneal anesthesia because of trigeminal insufficiency. However, this treatment alone is insufficient to prevent progressive anterior stromal opacification.     

Epithelial innervation of human cornea: a three-dimensional study using confocal laser scanning fluorescence microscopy

PURPOSE: Evaluation of a new method to visualize distribution and morphology of human corneal nerves (Adelta- and C-fibers) by means of fluorescence staining, confocal laser scanning microscopy, and 3-dimensional (3D) reconstruction. METHODS: Trephinates of corneas with a diagnosis of Fuchs corneal dystrophy were sliced into layers of 200 microm thickness using a Draeger microkeratome (Storz, Germany). The anterior lamella was stained with the Life/Dead-Kit (Molecular Probes Inc.), examined by the confocal laser scanning microscope "Odyssey XL," step size between 0.5 and 1 microm, and optical sections were digitally 3D-reconstructed. RESULTS: Immediate staining of explanted corneas by the Life/Dead-Kit gave a complete picture of the nerves in the central human cornea. Thin nerves running parallel to the Bowman layer in the subepithelial plexus perforate the Bowman layer orthogonally through tube-like structures. Passing the Bowman layer, Adelta- and C-fibers can be clearly distinguished by fiber diameter, and, while running in the basal epithelial plexus, by their spatial arrangement. Adelta-fibers run straight and parallel to the Bowman layer underneath the basal cell layer. C-fibers, after a short run parallel to the Bowman layer, send off multiple branches penetrating epithelial cell layers orthogonally, ending blindly in invaginations of the superficial cells. In contrast to C-fibers, Adelta-fibers show characteristic bulbous formations when kinking into the basal epithelial plexus. CONCLUSIONS: Ex-vivo fluorescence staining of the cornea and 3D reconstructions of confocal scans provide a fast and easily reproducible tool to visualize nerves of the anterior living cornea at high resolution. This may help to clarify gross variations of nerve fiber patterns under various clinical and experimental conditions.     

Ocular findings in Barsy syndrome

Report on a male newborn with progeroid aspect, cutis laxa, intrauterine growth retardation, bilateral dislocation of the hip, generalized anomalies of ossification, peripheral corneal opacification comparable to corneal senile arcus, a diffuse, very discrete clouding of the stroma and an anterior polar cataract OD. Diagnosis and differential diagnosis of other progeroid and cutis laxa syndromes are discussed on the basis of the corresponding ocular findings.     

In vivo confocal microscopy findings in a patient with posterior amorphous corneal dystrophy

A 21-year-old man, with bilateral posterior amorphous corneal dystrophy, was studied by biomicroscopy, corneal topography and in vivo confocal microscopy. The best-corrected visual acuity was 6/21 in the right eye and 6/6.9 in the left eye. Biomicroscopy revealed bilateral, asymmetric, sheet-like opacification at the deep posterior stromal layer. The corneal topography displayed asymmetric against-the-rule astigmatism in the right eye and prominent steepening at the inferior paracentral cornea in both eyes. In vivo confocal microscopy of the corneas demonstrated microfolds and hyper-reflective layer at the posterior stroma just adjacent to the endothelial layer. The epithelium, Bowman's membrane, anterior stroma and the endothelial layer were normal. In vivo confocal microscopy is useful in evaluating the corneal dystrophies.     

In vivo confocal microscopic findings of two siblings with Maroteaux-Lamy syndrome

PURPOSE: To describe the clinical and in vivo confocal microscopic findings of the cornea in 2 male siblings with Maroteaux-Lamy syndrome. METHODS: Two male siblings 27 and 22 years of age who had been diagnosed with Maroteaux-Lamy syndrome underwent ophthalmologic assessment. In vivo confocal microscopy of their corneas was performed with Confoscan 3.0 (Vigonza, Italy). RESULTS: Slit-lamp examination of the central and peripheral corneas of both siblings revealed mild haze and diffuse stromal opacities. The fundus examination of the older sibling was significant for left optic disc swelling and bilateral radial macular folds. In vivo confocal microscopy of the corneas of both cases revealed several microdeposits that were present extracellularly and within keratocytes in all stromal layers, ranging in size from 1.0 to 3.8 microm. Abnormal keratocytes containing hyporeflective vacuoles were present to a greater extent in the posterior and middle stromal layers compared with the anterior stroma. The endothelial cell layer, the subbasal nerve plexus, and the stromal nerves had normal morphologic features. CONCLUSIONS: In corneas of patients with Maroteaux-Lamy syndrome, glycosaminoglycan deposition and abnormal keratocytes may be present in all stromal layers. The endothelial layer seems to be normal at the third decade of life in both subjects studied.     

Unilateral congenital corneal keloid with anterior segment mesenchymal dysgenesis and subluxated lens: case report and review of literature

PURPOSE: To report the unusual association of unilateral congenital corneal keloid with anterior-segment mesenchymal dysgenesis and bilateral subluxated lens. METHODS: A 20-year old man presented with a mass lesion involving the left cornea. The corneal lesion had been present since birth. On biomicroscopic examination, a well-defined vascularized, grayish-white mass occupying the whole of the left cornea was seen. The right eye showed multiple peripheral corneal opacities with iridocorneal adhesions, a poorly defined supranasal limbus, and a subluxated lens. Excision biopsy of the mass was done for histopathologic examination. RESULTS: Histopathologic examination of the excised corneal mass showed features consistent with that of a corneal keloid: thickened keratinized epithelium, absent Bowman membrane layer, and fibrovascular hyperplasia composed of hyalinized collagen fibers with irregular orientation of the collagen lamellae. During penetrating keratoplasty of the left eye, an anomalous iris pattern with poorly defined angle and a supranasal subluxated lens was also observed. Extraction of the subluxated lens was also done. The graft failed subsequent to a nonhealing persistent epithelial defect. CONCLUSION: Our case report highlights the rare association of a unilateral congenital corneal keloid with anterior-segment mesenchymal dysgenesis and bilateral subluxated lens.     

Coexistent congenital hereditary endothelial dystrophy and congenital glaucoma

PURPOSE: To retrospectively evaluate the coexistence of congenital glaucoma with congenital hereditary endothelial dystrophy. METHODS: Ten infants presented to our hospital with diffuse corneal edema and bilaterally elevated intraocular pressure (IOP). These patients were diagnosed with congenital glaucoma. All patients underwent trabeculotomy with trabeculectomy for control of IOP. Although IOP was normalized in all patients, corneal edema persisted. These patients underwent penetrating keratoplasty, and the buttons were subjected to histopathologic examination. RESULTS: The corneal grafts remained clear in all patients. The histopathologic examination of the excised corneal buttons showed diffuse stromal edema, loss of the endothelial cell layer, and thickening of the posterior non-banded portion of the Descemet membrane, suggestive of congenital hereditary endothelial dystrophy. CONCLUSIONS: Congenital hereditary endothelial dystrophy may coexist with congenital glaucoma. This combination should be suspected where persistent and total corneal opacification fails to resolve after normalization of IOP.     

Cerebro-oculo-facio-skeletal syndrome

A three-month-old infant was referred with bilateral corneal opacities and microphthalmos. Pediatric examination as well as genetics consultation resulted in a diagnosis of the cerebro-oculo-facio-skeletal syndrome and should be included in the differential diagnosis of congenital cloudy corneas.     

Dermochondral corneal dystrophy (of François).

Dermochondral corneal dystrophy (of François) has been reported rarely in the literature. It consists of a triad of findings characterised by the development of skin nodules, acquired deformities of the extremities, and a corneal dystrophy. The corneal dystrophy is central and superficial with whitish subepithelial opacities. We present two brothers who display previously unreported ocular findings. Specifically, they developed confluent opacification of their central corneas with anterior stromal involvement, and peculiar anterior cortical cataracts. These findings should be added to the spectrum of findings seen in this rare disorder.     

Keratectasia after laser in situ keratomileusis. Clinicopathological case report

PURPOSE: To describe the morphological features of a prominent ectasia of the cornea after laser in situ keratomileusis (LASIK). METHODS: The morphology of the ectatic corneas was examined using corneal topography, light microscopy and transmission electron microscopy in 2 cases who underwent penetrating keratoplasty due to poor visual acuity induced by progressive corneal ectasia after LASIK. RESULTS: On topographic examination, the apex of the corneal surface was observed within the central 3-mm zone, and the smallest thickness was 0.116 and 0.271 mm in each case. On histological examination, the epithelial layer became thinner and detached easily. Bowman's membrane was broken down and folded. An irregular arrangement of the stromal lamellae with fibroblastic keratocytes was found. The fulled fiber cell, a transformed epithelial cell, was visible in a plane on Bowman's layer in the central region. In contrast, the corneal endothelium was intact, and no abnormality was found in both cases. CONCLUSION: On morphological examination of 2 cases with corneal ectasia, a forward protrusion of both the anterior and posterior corneal surfaces occurred, and epithelial detachment, Bowman's membrane breakage and folding and irregular lamellae were found. The 2 cases had greatly thinned and protruding corneas, yet there was no abnormality in the corneal endothelium.     

UV absorbance of the human cornea in the 240- to 400-nm range

PURPOSE: To determine the UV absorbance of the corneal layers (epithelium, Bowman layer, stroma) in the 240- to 400-nm range. METHODS: Consecutive slices (100 microm) of human cadaveric corneas were cut, and the UV absorbance of each sample was determined in a scanning spectrophotometer. In some cases the epithelium was scraped off and its absorbance measured separately. RESULTS: The investigation of the UV-B absorption of consecutive corneal slices revealed evidence that UV-B absorption is 1.8 times higher in the anterior 100 microm of the human cornea than in the posterior layers. The UV absorbance of the posterior layers was uniform, showing no further structural dependence. The epithelium and Bowman layer are both effective absorbers of UV-B radiation. CONCLUSIONS: These results suggest that the anterior corneal layers are particularly important in preventing damage by UV-B radiation.     

Findings in the anterior segment on ultrasound biomicroscopy in Maroteaux-Lamy syndrome

PURPOSE: Maroteaux-Lamy syndrome is one of the mucopolysaccharidoses caused by enzyme deficiency (arylsulfatase B) that leads to incomplete degradation and storage of dermatan sulfate. We report a case of mucopolysaccharidosis type VI (MPS VI; Maroteaux-Lamy syndrome) with corneal involvement and introduce ultrasound biomicroscopy (UBM) as an examination with which to follow disease progression in relation to deposition in cornea, angle, and iris. METHODS: We describe a 11-year-old boy with a clinical and laboratorial diagnosis of MPS VI who developed increasing bilateral corneal opacification and decreased visual acuity. He underwent two seriate UBM (50-MHz transducer) evaluations. RESULTS: UBM examination showed diffuse and homogeneous stromal hyper-reflective deposit in both eyes and an increase in peripheral corneal thickness throughout time. CONCLUSION: High-frequency ultrasound documentation of corneal deposit and anterior segment involvement in a patient with Maroteaux-Lamy syndrome is unique, and follow-up revealed thickening of the corneal periphery, which may be related to the progression of the disease (continuous mucopolysaccharide deposits in corneal stroma). UBM was used to locate and document the deposit, as well as to accompany the deposit's evolution, characterizing corneal changes and angle structure involvement.     

In vivo confocal microscopy of patients with corneal recurrent erosion syndrome or epithelial basement membrane dystrophy

OBJECTIVE: To characterize morphologic changes in corneas of patients with recurrent erosion syndrome or epithelial basement membrane dystrophy using in vivo confocal microscopy. DESIGN: Observational case series PARTICIPANTS: Fourteen eyes of eight patients with diagnosed epithelial basement membrane dystrophy and 13 eyes of seven patients with recurrent erosion syndrome were examined. METHODS: Slit-lamp examination and in vivo confocal microscopy. The pathologic findings are presented as digitized images obtained from video tape recorded during the confocal microscopy. MAIN OUTCOME MEASURES: The morphology of corneal surface epithelial cells, basal epithelial cells, subbasal nerve plexus, Bowman's layer, stromal keratocytes, and endothelium was analyzed. RESULTS: The surface epithelium was intact in all but two eyes. One cornea (a basement membrane disorder with clinically visible dots) had multinucleate surface epithelial cells, and one eye with recurrent corneal erosions showed a freely floating surface epithelium sheet in the tear fluid. Patients in both groups showed islets of highly reflective cells with presumed intracellular deposits surrounded by normal cells in the basal epithelial cell layer. The basal epithelial cell area also showed other pathologic changes, including drop-shaped configurations, streaks, or ridges. Folding of the Bowman's layer was also observed in both groups. Anterior keratocytes showed signs of activation (highly reflective nuclei with visible processes) in some of the patients regardless of the clinical diagnosis, and in recurrent erosions even increased deposition of abnormal extracellular matrix in the anterior stroma was suspected. Posterior corneal keratocytes and endothelium appeared normal when examined. The subbasal nerve plexus showed various pathologic changes, such as short or strangely shaped nerve fiber bundles, decreased numbers of long nerve fiber bundles, only faintly visible long nerve fiber bundles (instead of the normally observed long parallel running interconnected bundles), or increased amounts of Langerhans cells, but only one patient (with recurrent erosion syndrome) lacked the subbasal nerve plexus. CONCLUSIONS: In vivo confocal microscopy of corneas with recurrent erosions or epithelial basement membrane dystrophy showed deposits in basal epithelial cells, subbasal microfolds and streaks, damaged subbasal nerves, or altered morphology of the anterior stroma. Confocal microscopy cannot replace biomicroscopy in making a specific diagnosis, but it sometimes helps the diagnosis in corneas that appear normal under a biomicroscope.     

Second-harmonic imaging microscopy of normal human and keratoconus cornea

PURPOSE: The purpose of this study was to evaluate the ability of second-harmonic imaging to identify differences in corneal stromal collagen organization between normal human and keratoconus corneas. METHODS: Six normal corneas from eye bank donors and 13 corneas of patients with keratoconus, obtained after penetrating keratoplasty were examined. A femtosecond titanium-sapphire laser with 800-nm output was used to generate second-harmonic signals collected at 400 nm from central and paracentral corneal tissue blocks. Three-dimensional (3-D) data sets were collected and reconstructed to evaluate the location and orientation of stromal collagen lamellae. RESULTS: Imaging of second-harmonic signals combined with 3-D reconstruction of the normal cornea identified a high degree of lamellar interweaving, particularly in the anterior cornea. Of note was the detection of lamellae that inserted into Bowman's layer and were oriented transverse to the corneal surface, penetrating posteriorly approximately 120 mum. In keratoconus corneas, imaging second-harmonic signals identified less lamellar interweaving and a marked reduction or loss of lamellae inserting into Bowman's layer in 12 of 13 cases, particularly in regions associated with cone development without breaks in Bowman's layer or scarring. CONCLUSIONS: Compared with normal adult corneas, marked abnormalities were detected in the organization of the anterior corneal collagen lamellae of keratoconus corneas by second harmonic imaging. These structural abnormalities are consistent with the known changes in collagen organization and biomechanical strength of keratoconus.     

Wound healing following anterior keratectomy and lamellar keratoplasty in the pig

PURPOSE: To examine corneal wound healing in an animal model of two types of mechanical lamellar keratectomy. METHODS: One eye from each of 28 pigs was studied. Using a motorized keratome, corneas were subjected to an anterior lamellar keratectomy with removal of anterior stroma and epithelium, or to automated lamellar keratoplasty (ALK) with reapposition of a corneal flap. The exposed stromal surfaces were labeled intraoperatively with a fluorescent dye (DTAF) to assess deposition of stromal components during subsequent wound healing. Examination before surgery and enucleation included measurement of corneal curvature and intraocular pressure, and assessment of corneal haze. Eyes were prepared for histological examination, fluorescence microscopy, and for fibronectin immunohistochemistry. RESULTS: Both keratectomy procedures produced flattening of corneas by up to 3.80 diopters, 28 days after surgery. Corneal haze was more pronounced in eyes from which epithelium was removed (anterior lamellar keratectomy group). The increased haze in this group was associated histologically with appearance of many reactive keratocytes and inflammatory cells, deposition of new stromal material, and more widespread appearance of fibronectin immunoreactivity. In the lamellar keratoplasty group, only the edges of the corneal wound showed significant reactivity, and included keratocyte activation and epithelial ingrowth. CONCLUSIONS: The pig provides a useful model for studies of refractive surgical techniques using procedures and instruments designed for use in humans. Mechanized keratectomy procedures that minimize disruption of the epithelium and Bowman's layer produce a less reactive corneal wound than procedures in which an expanse of epithelium and anterior stroma are removed.     

圆锥角膜各期的共焦显微镜表现

目的评价共焦显微镜在圆锥角膜临床研究中的应用价值。方法应用共焦显微镜观察圆锥角膜患者32例（48眼）及正常对照组17例（28眼），分别比较早、中、晚期圆锥角膜与正常对照组的图像特点。结果早期圆锥角膜出现激活状态的角膜细胞、浅基质层的细小皱褶、深基质层的暗纹、部分内皮细胞异形性明显，中、晚期圆锥角膜出现角膜上皮细胞拉伸、细胞核皱缩；基质细胞排列紊乱、基质层暗纹；而对照组未发现上述表现。各期圆锥角膜的角膜基质层厚度、不同深度角膜基质细胞密度、内皮细胞密度与对照组之间差异有统计学意义（P〈0．05）。结论共焦显微镜对早期圆锥角膜的发现以及圆锥角膜病理发展的研究具有重要的临床价值。     

Posterior amorphous corneal dystrophy. An ultrastructural study of a variant with histopathological features of an endothelial dystrophy.

Posterior amorphous corneal dystrophy (PACD) is a rare autosomal-dominant disease, generally classified with the pre-Descemet's dystrophies. It is characterized by deep stromal corneal opacification, flat corneas with low keratometry values, and central thinning. To our knowledge, only one previous ultrastructural study has been published on this disease. This 5-year-old white boy presented with best corrected vision (20/50 right and 20/60 -2 left). The corneas had dense opacities, bilaterally, deep in the corneal stroma. Keratometry was 39.50/40.50, bilaterally. The patient's father had 20/20 vision, bilaterally, with minimal opacifications in the deep corneal stroma. A penetrating keratoplasty was performed. In contrast to the previously reported case of PACD, in which the abnormalities were largely limited to the stroma, our patient had subepithelial deposits, only mild stromal abnormalities, and a thick collagenous layer posterior to Descemet's membrane, thus suggesting that this variant of PACD is a generalized corneal disease including endothelial and epithelial abnormalities, rather than a pure stromal dystrophy.