Stromal demarcation line induced by corneal cross-linking in eyes with keratoconus and nonkeratoconic asymmetric topography.

PURPOSE: To evaluate stromal demarcation lines following corneal cross-linking (CXL) using anterior segment optical coherence tomography in patients with keratoconus and nonkeratoconic asymmetric topography. METHODS: Fifth-nine eyes of 59 patients were enrolled in a retrospective comparative case series, of which 19 eyes had keratoconus and 40 eyes had asymmetric topography. Eyes with asymmetric topography were treated in preparation for photorefractive keratectomy. One month after CXL, a stromal demarcation line was evaluated at 5 standardized corneal points using anterior segment optical coherence tomography. RESULTS: Mean stromal demarcation line depths were measured at 5 points on the cornea, namely, centrally, 3.0 mm temporally, 1.5 mm temporally, 3.0 mm nasally, and 1.5 mm nasally. For the keratoconus group, the values were 178 ± 47, 123 ± 15, 152 ± 47, 125 ± 23, and 160 ± 43 µm, respectively. For the asymmetric corneal topography group (without keratoconus), they were 305 ± 64, 235 ± 57, 294 ± 50, 214 ± 54, and 285 ± 58 µm, respectively. There was no correlation between central corneal pachymetry and stromal demarcation line depth in all 5 measured corneal points in both groups. CONCLUSIONS: CXL treatment profiles are similar in keratoconic and nonkeratoconic eyes with asymmetric topography.

Different corneal epithelial healing mechanisms in rat and rabbit: role of actin and calmodulin.

The authors investigated the effects of calmodulin inhibitors, trifluoperazine (10-20 microM) and W-7 (25-50 microM), and of cytochalasin B (5 micrograms/ml) on the F-actin distribution, surface morphology, and migration of rat and rabbit corneal epithelial cells in tissue culture. In the rat, actively migrating cells have abundant F-actin-containing stress fibers and numerous cytoplasmic extensions of the plasmalemma. These features, and ultimately cell migration, are inhibited by calmodulin inhibitors and cytochalasin B. In the rabbit, migrating cells are devoid of stress fibers and cytoplasmic extensions. Cell migration is not inhibited by calmodulin inhibitors but is arrested by cytochalasin B. The cell-to-substrate adhesion is reduced by calmodulin inhibitors in both rat and rabbit. These findings corroborate our earlier observations in organ culture studies and support the view that corneal epithelial cell migration is calmodulin-dependent in the rat, while it is not in the rabbit. The complete blockage of migration in both species by cytochalasin B suggests that actin polymerization is critical for corneal epithelial locomotion in both species.

EGF does not enhance corneal epithelial cell motility.

Although it is well known that epidermal growth factor (EGF) accelerates corneal epithelial wound healing by stimulating mitosis, it is also believed that EGF may directly stimulate the motility of individual corneal epithelial cells. We employed three different experimental methods to determine if EGF does indeed enhance the motility of corneal epithelial cells (independent of mitotic effects). First, the effects of EGF on the motility of tissue-cultured rat and rabbit corneal epithelial cells were investigated by a Boyden chamber assay. In rat corneal epithelium, these effects were further investigated by a second method, the agarose drop assay. Both assay techniques demonstrated no increase in corneal epithelial cell motility in the presence of EGF. These findings were corroborated by a third method which consisted of measuring the closure rate of epithelial wounds in organ-cultured rat corneas in the presence and absence of EGF, while concurrently arresting mitosis with colchicine. The wound closure rate before addition of any drug was 0.46 +/- 0.03 mm2/hr. The wound closure rate with EGF (50 ng/ml) was 0.55 +/- 0.03 mm2/hr, significantly (P less than 0.005) more rapid than the drug-free controls. However, when EGF (50 ng/ml) and colchicine (40 micrograms/ml) were used simultaneously, the acceleration of wound closure by EGF was completely negated by the presence of colchicine, resulting in a wound closure rate (0.46 +/- 0.06 mm2/hr) that did not differ significantly (P greater than 0.50) from that of the drug-free control.(ABSTRACT TRUNCATED AT 250 WORDS)

Movements of cultured corneal epithelial cells and stromal fibroblasts in electric fields.

The effects of an externally applied direct-current electric field on the movement of cultured rabbit corneal epithelial cells and stromal fibroblasts were studied. After a latency of approximately 20 minutes in an electric field, both epithelial cells and stromal fibroblasts became spindle shaped and underwent galvanotropism by aligning their long axes perpendicular to the applied electric field. The electric field stimulus thresholds for galvanotropic movements in epithelial cells and stromal fibroblasts were 4V/cm and 6 V/cm, respectively. After an additional latency of 30 minutes, both cell types manifested galvanotaxic movements: epithelial cells commenced migration in the cathodal (downfield) direction and stromal fibroblasts in the anodal (upfield) direction. For both types of cells, ruffled membranes and lamellipodia were abundant at the leading edges of migrating cells and cell processes underwent retraction at the trailing edges. At field strengths of above 10 V/cm, evidence of cellular damage (manifested by cellular rounding and detachment), attributable to the electric field treatment, was observed after 4 hours. These preliminary results suggest that galvanotaxic responses could be exploited clinically in the enhancement of corneal wound healing.

Vinculin in focal cell-to-substrate attachments of spreading corneal epithelial cells.

Vinculin is a specialized protein with a molecular weight of 130 kilodaltons that is localized to focal regions of cell-to-substrate attachment. It is located precisely at the termini of actin-containing intracytoplasmic stress fibers, which appear to insert into the inner surface of the cell membrane via the vinculin junctions. By double-labeling corneal epithelial cells in tissue culture simultaneously for vinculin and actin, the intimate association of stress fibers and cell-to-substrate adhesion foci was demonstrated. At the leading edge of the migrating epithelial sheet, discrete vinculin patches were numerous in the direction of cell movement, while vinculin was less polarized and often diffusely distributed in the cytoplasm in the less motile cells toward the center of the cell colony. This study shows that corneal epithelial cell migration and spreading during wound healing is characterized by relatively firm substrate attachments at the advancing edge, with the cells behind the edge possibly being pulled forward via cytoskeletal contractile mechanisms.

Dellen associated with filtering blebs.

Dellen may occur in the corneas of eyes with filtering blebs. Nine cases of such dellen were encountered in a series of 97 consecutive trabeculectomies. In two such patients, the dell progressed to a deep corneal ulcer, although in most cases it healed uneventfully with minor changes in therapy. The use of topical prednisolone acetate during the postoperative period may also contribute to dellen formation by inhibiting corneal epithelial wound healing. However, the most important factor predisposing to dellen formation was poor tear-film integrity adjacent to the bleb. The secretion of the aqueous tears seemed to have little or no effect on dellen formation. Almost all dellen occurred in eyes with large filtering blebs.

Actin in human corneal epithelium.

Actin, a major protein involved in muscle cell contraction, is also associated with cell motility, cell-substrate adhesion, and cell-shape changes in non-muscle cells. By electrophoresis and scanning densitometry, actin was found to constitute about 4% to 6% of the total cellular protein in the human corneal epithelium. The fluorescent probe, NBD-phallacidin, which specifically binds to filamentous actin (F-actin), was used to demonstrate the distribution of this protein in cultured corneal epithelial cells obtained from human eyebank eyes. Actin was present in the cytoplasm in two, often coexisting, patterns: (1) within numerous parallel and convergent linear bundles known as stress fibers, and (2) diffusely in the cytoplasm, with a cortical region of increased density in the peripheral cytoplasm adjacent to the plasmalemma. Actin has been implicated in the generation of cellular movement forces during the migration phase of corneal epithelial healing. Stress fibers, however, may not be absolutely necessary for the generation of the actual locomotive forces, but may function instead in anchoring the cell to the substrate and in elaborating cell-shape changes during cell spreading.

Branch artery occlusion. An unusual complication of external carotid embolization.

A case of retinal branch artery occlusion was caused by migration of emboli, presumably via collateral circulation, during therapeutic embolization of the maxillary artery. Migration of particles to the ophthalmic circulation is unusual with embolization of the branches of the external carotid artery. Meticulous technique, careful angiographic monitoring, and proper selection of embolic material may reduce, but not eliminate, migration of emboli to undesirable locations. Therapeutic embolization of vascular tumors and malformations in the external carotid territory is a recent radiologic innovation that is becoming increasingly popular. Therefore, we may expect to see more ocular complications from aberrant emboli as the use of this technique becomes more widespread.

Fibronectin does not enhance epidermal growth factor-mediated acceleration of corneal epithelial wound closure.

Concomitant use of epidermal growth factor and fibronectin for the treatment of corneal epithelial wounds has a putative advantage of promoting complementary aspects of wound healing: epidermal growth factor enhances mitosis, while fibronectin increases cell-to-substrate adhesiveness and possibly cell motility. To determine if the combination of epidermal growth factor and fibronectin is synergistic in accelerating the speed of corneal epithelial wound coverage, epithelial wound closure rates were compared in serum-free rat corneal organ cultures among epidermal growth factor alone, fibronectin alone, their combination, and drug-free controls. Epidermal growth factor (50 to 1000 ng/mL) significantly increased the rate of wound closure over that of the drug-free controls, while fibronectin (50 to 100 micrograms/mL) had not significant effect. Wound closure rates with combined epidermal growth factor and fibronectin were no faster than with epidermal growth factor alone. The results indicate that fibronectin does not accelerate the rate of corneal epithelial migration when used alone or in combination with epidermal growth factor. This may reflect that the major role of fibronectin may be in the enhancement of cell-to-substrate adhesion and not of migration per se.

Implantation of posterior chamber intraocular lenses in the absence of lens capsule during penetrating keratoplasty.

We retrospectively studied the clinical records and the corneal endothelial cell counts of 133 consecutive eyes that received sutured posterior chamber intraocular lenses during penetrating keratoplasty in the absence of lens capsular support. Postoperative follow-up time ranged from three to 24 months, with 82 patients having at least one year of follow-up. At one year, 45.1% of these patients had 20/40 or better visual acuity, 30.5% had a visual acuity between 20/50 and 20/100, and 24.4% had a visual acuity of 20/200 or worse. At two years, 63.6% had a visual acuity of 20/40 or better, 18.2% had a visual acuity between 20/50 and 20/100, and 18.2% had a visual acuity of 20/200 or worse. Ninety-seven percent of the grafts remained clear at their latest follow-up examination. Cystoid macular edema (36.4%) and age-related macular degeneration (14.0%) accounted for poor visual acuity in most cases. Less common problems included graft rejection, retinal detachment, glaucoma, and endophthalmitis. At one year, the endothelial cell loss in the grafts averaged 19% with sutured posterior chamber intraocular lenses.

In situ actin distribution in excised retrolental membranes in retinopathy of prematurity.

Actin, an intracellular contractile protein, is associated with cell movements in both muscle and nonmuscle tissues. Using the fluorescent derivative of the mushroom toxin, phallacidin, which specifically binds to polymerized (filamentous) actin, we demonstrated the distribution of actin in retrolental membranes excised during open-sky vitrectomy from six infants with leukokoria due to retrolental fibroplasia. Actin was detected in ubiquitous linear bundles, which is consistent with the existence of contractile forces. Actin was also concentrated in the cortical cytoplasm of cells, thus outlining the plasma membranes. Transmission electron microscopy has identified many of these cells to be myofibroblastlike in appearance. Myofibroblasts are known to contract like smooth-muscle cells and have been reported as the putative causal factor in the contraction of scars and transvitreal membranes.

Ocular involvement associated with chronic Epstein-Barr virus disease.

Ocular involvement with acute Epstein-Barr virus infection is usually limited to a transient follicular conjunctivitis, although other lesions have been reported. Chronic Epstein-Barr virus infection has recently gained attention, but ocular manifestations have not been emphasized. We describe three patients with chronic infection with prominent ocular involvement. Bilateral uveitis was noted in all patients, ranging from an anterior uveitis that was responsive to steroids to a severe panuveitis with vitritis, cataract, optic disc swelling, and macular edema. In one patient, topical acyclovir ointment resulted in a substantial decrease in the inflammatory reaction when added to systemic acyclovir therapy. Another patient displayed a keratitis that resolved with topical steroid therapy. Cataract and vitreous surgery were also beneficial in the management of these patients.

Immune-mediated subepithelial blistering diseases of mucous membranes. Pure ocular cicatricial pemphigoid is a unique clinical and immunopathological entity distinct from bullous pemphigoid and other subsets identified by antigenic specificity of autoantibodies.

BACKGROUND AND DESIGN: There is much confusion in the clinical classification of immune-mediated subepithelial blistering diseases of mucous membranes. We conducted a 6-year comprehensive study to better classify this heterogeneous disease group. Indirect immunofluorescence was performed on a salt-split-skin substrate to detect circulating antibasement membrane antibodies (n = 47). Serologic reactivity against cultured keratinocyte antigens was examined by immunoblots (n = 38) and immunoprecipitation (n = 15). The results were correlated with the clinical features and direct immunofluorescence data of the entire patient group (n = 87) without preassignment of clinical diagnoses. chi 2 Statistical analyses compared these results with those of the classic bullous pemphigoid group (n = 36). RESULTS: When compared with the bullous pemphigoid patients, a subset of patients with combined oral mucosal and skin lesions demonstrated marked similarity in direct and indirect immunofluorescence findings and in serologic reactivity to bullous pemphigoid antigens. By contrast, a subset of patients with only ocular lesions exhibited significantly lower in vivo deposits of IgG and C3, higher deposits of fibrin, virtual absence of circulating antibodies, and negative serologic reactivity to bullous pemphigoid antigens. CONCLUSIONS: Ocular patients without skin or mouth lesions, in particular those with negative indirect immunofluorescence, should be distinctively classified as ocular cicatricial pemphigoid, a unique clinical and immunopathologic entity. Patients with mucous membrane involvement who also demonstrate skin lesions and antibodies to the root of salt-split-skin substrate should be classified as anti-BP Ag mucosal pemphigoid, even though they may exhibit severe oral and/or ocular diseases. The remaining mucous membrane patients are heterogeneous. Some can be classified on the basis of autoantibodies to other basement membrane determinants, or if serum autoantibody negative, on the basis of clinical features (ie, pure oral mucosal pemphigoid or overlapping mucosal involvement).

Small, overlapping tectonic keratoplasty involving graft-host junction of penetrating keratoplasty.

PURPOSE: To report the indications for and postoperative course of small tectonic keratoplasties overlapping (and involving) the graft-host junction of preexisting penetrating keratoplasties. METHODS: A retrospective study of 15 consecutive eyes (15 patients) with small tectonic keratoplasties overlapping the graft-host junction of preexisting penetrating keratoplasties. RESULTS: After tectonic keratoplasty, follow-up times ranged from 5 months to 20 years (mean, 69 months). Clinical indications included sterile corneal ulceration (seven cases), bacterial keratitis (six cases), and fungal keratitis (two cases). In the six cases with bacterial keratitis, five were suture abscesses, with four resulting in wound dehiscence. Ten tectonic grafts were lamellar keratoplasties, and five were penetrating keratoplasties. Postoperative best-corrected visual acuities were unchanged from preoperative levels in every patient. After tectonic grafting, the mean +/- SD change in keratometric astigmatism in the parent penetrating keratoplasty was 1.75 +/- 1.50 diopters. The astigmatism increased in 10 cases, decreased in three, and remained unchanged in two. There was no case of recurrent ulceration or wound dehiscence in or around the tectonic grafts. The surgery did not result in new glaucoma or worsening of preexisting glaucoma. CONCLUSIONS: In the treatment of infectious or ulcerative foci at or near the graft-host junction of penetrating keratoplasties, a small extirpative, tectonic graft over the diseased junction appears to be a safe and effective alternative to either repeating the original penetrating keratoplasty or performing an oversize transplant.

A study of race matching between donor and recipient in corneal transplantation.

We investigated the influence of a racial match or mismatch between the corneal donor and recipient on the risk of endothelial rejection and subsequent graft failure in 998 corneal transplant recipients. Actuarial survival analysis showed no significant difference in the cumulative risk of endothelial rejection between the 676 race-matched and 322 race-mismatched recipients. Recipients who had preoperative factors that placed them at a higher risk of endothelial rejection (n = 208) also were not subject to a higher incidence of endothelial rejection if they received race-mismatched tissue. Graft failure after endothelial rejection was not found to differ among race-matched or -mismatched groups.

Corneal astigmatism from conjunctival cysts.

Two patients had decreasing visual acuity because of corneal astigmatism induced by a conjunctival cyst. In both cases, surgical removal of the cyst resulted in marked improvement because of a reduction in astigmatism. In one case, the cause of decreased visual acuity was unknown for two years; keratometry and a careful examination of the eyelids disclosed the cyst.

Conjunctival mucoepidermoid carcinoma in a young HIV-infected man.

PURPOSE: To report a case of conjunctival mucoepidermoid carcinoma occurring in a long-standing pterygium in a 33-year-old Cambodian man infected with the human immunodeficiency virus (HIV). METHODS: Review of clinical history and histopathologic findings. RESULTS: A pterygium that was present for 8 years suddenly became highly inflamed and underwent rapid growth. After the initial diagnostic conjunctival and corneal biopsy showed mucoepidermoid carcinoma, subsequent additional deep excisions of the adjacent sclera and cornea were necessary to completely excise the tumor. Cytokeratin and mucicarmine stains were used to confirm the pathologic diagnosis of mucoepidermoid carcinoma. CONCLUSIONS: Unique features of this case include the extremely young age of the patient (perhaps rendered susceptible by his HIV infection), the tumor masquerading as a pterygium, and the use of a hybrid lamellar and full-thickness corneoscleral resection requiring a complementary graft. Seventeen months after the resection, the patient is free of tumor; this was histopathologically confirmed with multiple random conjunctival biopsies.

Penetrating keratoplasty for corneal scarring due to herpes zoster ophthalmicus.

We retrospectively studied the postoperative results in nine patients with corneal scarring due to herpes zoster ophthalmicus who underwent penetrating keratoplasty. This was a highly selected group that satisfied all of the following criteria: (a) absence of active disease of the ocular surface and eyelids, (b) intraocular pressure under control, and (c) absence of active keratouveitis. Penetrating keratoplasty after herpes zoster ophthalmicus may do well in patients with long preoperative quiescent periods in whom these restrictive preoperative criteria are observed.

Non-tuberculous mycobacterial keratitis: a study of 22 cases.

AIM: To investigate causes and clinical findings of non-tuberculous mycobacterial keratitis, and to study its response to topical antibiotic therapy and surgical extirpative keratectomy. METHOD: A single centre, retrospective review of 22 patients with non-tuberculous mycobacterial keratitis seen in a 3 year period. Laboratory diagnoses were established with Ziehl-Nielsen acid fast staining and Löwenstein-Jensen cultures. RESULTS: In 20 patients (91%), there was an antecedent history of foreign body eye trauma (18 patients) or elective surgery (two patients). There were 19 cases of Mycobacterium chelonei, and three of M fortuitum. Clinical signs included epithelial defects, satellite or ring stromal infiltrates, crystalline keratopathy, and hypopyon. For topical antibiotic therapy, 20 patients received amikacin, while one patient received rifampin and another received ciprofloxacin, each in accordance with the results of the in vitro drug sensitivities. An extirpative keratectomy was performed in 15 cases; four of these cases additionally required a temporary conjunctival flap in order to finally eradicate the infection. At the end of the follow up period (median 18 months; range 3 months to 3 years) all eyes were stable and free of infection, with 19 (86%) having final visual acuities of 20/200 or better. CONCLUSION: Early clinical recognition and prompt laboratory diagnosis, together with aggressive topical antibiotic therapy and early keratectomy, may shorten morbidity and improve the clinical outcome of non-tuberculous mycobacterial keratitis.

Hereditary hemorrhagic telangiectasia diagnosed by the ophthalmologist.

PURPOSE: To show the clinical features of a case of hereditary hemorrhagic telangiectasia in which the diagnosis was prompted by ophthalmologic examination. METHODS: A retrospective case review of a 56-year-old East Indian woman whose presentation to the eye clinic with a history of bloody tears and conjunctival vascular malformations prompted a systemic evaluation that resulted in the diagnosis of hereditary hemorrhagic telangiectasia. RESULTS: The diagnosis of hereditary hemorrhagic telangiectasia was eventually confirmed by gastrointestinal endoscopy and otorhinolaryngologic examination. CONCLUSION: Although hereditary hemorrhagic telangiectasia is typically diagnosed on the basis of gastrointestinal and otorhinolaryngologic history and examination, the ophthalmologic features of this case were striking enough to arouse suspicion of this disease.