How do tears exit?

The mechanisms of tear flow, blinking, and tear drainage were studied employing high speed slit-lamp cinematography using a polystyrene microsphere suspension as a tracer of tear movement. It was demonstrated that: (1) Tears are drawn into the canaliculi during the relaxation phase of blinking. (2) Both superior and inferior puncta function as normal tear drainage routes. (3) The superior punctum alone is sufficient to handle tear drainage. (4) There is some regurgitation of tears from the canaliculi. (5) An intact blink mechanism is necessary for effective tear drainage. (6) There is an actual closure of the puncta during blinking. This is sufficient to effect tear exit without the lids meeting. The clinical impression that in order to effectively prevent tear drainage in the treatment of dry eyes, it is necessary to occlude both the superior and inferior puncta was confirmed.

Polymer adsorption at the ocular surface.

A new method for measuring ocular adsorption of polymers in solution and their resistance to removal by rinsing has been developed. The adsorptive properties of artificial tear solutions and mucin have been determined. Several solutions display properties similar to mucin and two seem to resist removal by rinsing.

Return of human corneal sensitivity after penetrating keratoplasty.

To evaluate the reinnervation of corneal grafts, we studied 91 eyes of 79 patients for the return of sensitivity one month to ten years following penetrating keratoplasty for various corneal disorders including keratoconus, Fuchs' dystrophy, herpes simplex keratitis, aphakic and pseudophakic bullous keratopathy, glaucoma, trauma, and interstitial keratitis. Using the Cochet-Bonnet esthesiometer, a sensation was recorded in the center of the graft no earlier than 18 months. We found a progressive return of sensitivity from the periphery toward the center of the graft. Regression analysis indicated a rate of return of sensitivity that averaged 0.029 mm/mo for each diagnostic category except herpes simplex keratitis. The slope of the return of sensitivity in the group with herpes simplex keratitis was essentially flat, showing no central progression. None of the eight patients with herpes simplex keratitis had a sensation recorded further than 0.5 mm from the wound margin.

Association of rosacea and keratoconjunctivitis sicca.

Sixty consecutive patients with active ocular rosacea underwent Schirmer's test without anesthesia. A randomly selected group of 120 patients without rosacea, matched for age and sex, served as controls. The prevalence of dry eyes was significantly greater in the patients with rosacea. The coexistence of keratoconjunctivitis sicca and ocular rosacea probably causes a high level of symptoms that lead patients to examination and recognition.

Autoimmune phenomena of the conjunctiva and cornea. A case report.

A 20-year-old woman had erosions of the corneal and conjunctival epithelium and sterile stromal ulcerations of the cornea necessitating multiple corneal grafts, which were unsuccessful. An immunopathological basis for her disease was suggested by the demonstration of tissue-fixed antibodies and complement in her own conjunctival epithelium by direct immunofluorescence. In addition, circulating antibodies to normal corneal and conjunctival epithelium were demonstrated in the patient's serum by indirect immunofluorescent techniques and the titer of circulating antibodies was found to correlate with disease activity. The involvement of the fellow eye after evisceration of the first eye and reduction of systemic steroids in association with a greatly elevated level of circulating antibodies provided additional evidence for an autoimmune process. A background of immunological susceptibility was found in the patient and her family by history and immunological examination.

Meibomian gland dysfunction.

Blepharitis is probably the most common disease entity seen in the general ophthalmologist's office. A significant proportion of these cases are secondary to meibomian gland disease. This review outlines our knowledge of the histopathology, lipid abnormalities and role of microorganisms in meibomian gland dysfunction. We will also review the physiology of meibomian gland secretion and present models of meibomian gland dysfunction which have enhanced our knowledge of this condition. The importance of diagnosing associated conditions such as aqueous tear deficiency, contact lens intolerance, rosacea, and seborrheic dermatitis is emphasized. Although this condition causes significant morbidity in the population, there are effective treatments available and these will be discussed.

Tear physiology and dry eyes.

The conditions of tear film formation and stability are governed by the surface chemical characteristics of the tear film system and by the proper functioning of the lacrimal apparatus. The tear film has to remain continuous between blinks in order to fulfill it function. The presence of an abnormal tear film results in dry eye states that can be detrimental to vision. The diagnostic tests presently available are limited mainly to approximately determining tear secretion rate and estimating epithelial damage by staining techniques. The only test that directly measures tear film stability is one which determines tear film breakup time. The treatment modalities depend on the type of irregularity causing the dry eye state and range from the application of artificial tear substitutes or the obstruction of the puncta to surgical alterations of the lacrimal system.

The effect of extended-wear aphakic hydrophilic contact lenses after penetrating keratoplasty.

I fitted nine aphakic patients who had undergone penetrating keratoplasty with extended-wear hydrophilic contact lenses (55% to 80% water content). All patients had edematous host corneas. Eight of nine developed vascularization of the graft after two to 30 weeks of contact lens wear. One patient developed a presumed Candida keratitis. The development of vascularization of the graft suggests that patients with grafted corneas are at special risk with extended-wear hydrophilic contact lenses.

Toxic endothelial degeneration in ocular surface disease treated with topical medications containing benzalkonium chloride.

We examined a 56-year-old man with keratoconjunctivitis sicca and marked ocular surface disease in whom the prolonged frequent use of topical medications containing the preservative benzalkonium chloride was associated with corneal endothelial damage requiring corneal transplantation in one eye. The histopathologic findings on examination of the excised button were consistent with toxic endothelial disease. Postoperatively, the patient's symptoms continued until the preservative-containing medications were substituted with nonpreserved saline eyedrops.

Rapid development of band keratopathy in dry eyes.

In three patients, calcium deposits rapidly developed within the superficial corneal stroma. All eyes had severe desiccation, a bacterial corneal ulcer, and frequent instillation of an artificial tear preparation. Calcium deposition within the ulcer base occurred within two to three weeks.

The effects of extended-wear hydrophilic contact lenses on the human corneal epithelium.

We used wide-field color specular microscopy of the human corneal surface to study the morphologic changes that occur under extended-wear contact lenses. There was a shift in the frequency distribution of surface cells by size to larger cells, suggesting a prolonged residence time on the ocular surface. Other abnormalities included retained desiccated mucin, coarse mucus plaques, and palisading of cells.

An in vivo study of corneal surface morphologic features in patients with keratoconjunctivitis sicca.

We used wide-field color specular microscopy to study the corneal epithelium of 13 normal subjects and 13 patients with keratoconjunctivitis sicca. The frequencies of small, medium, and large cells were different in the two groups, with a shift to small cells in patients with keratoconjunctivitis sicca. Increased uptake of rose bengal dye, filaments, coarse mucus plaques, and pre-exfoliative sheets were also found in the patients with keratoconjunctivitis sicca. These findings suggest accelerated epithelial cell loss from the surface of the eye in keratoconjunctivitis sicca.

Estrogen and progesterone receptors and human conjunctiva.

Freshly frozen conjunctival tissue from premenopausal and postmenopausal women and male subjects were processed for estrogen and progesterone receptors by using monoclonal antibodies and a peroxidase-antiperoxidase technique. No immunocytochemical staining was localized in the nuclei of the cells treated with the monoclonal antibodies to human estrogen receptor or human progesterone receptor in any of the conjunctival specimens, in contrast to the strongly positive staining in breast adenocarcinoma controls. Immunocytochemical staining disclosed no evidence for estrogen or progesterone receptors on cells of the ocular surface.

Immunopathology and electron microscopy of Acanthamoeba keratitis.

In order to evaluate the local cellular immune response to Acanthamoeba infection we performed immunohistochemical examinations of the corneal buttons of two patients with Acanthamoeba keratitis. We found that the corneal stroma was infiltrated with polymorphonuclear leukocytes and HLA-DR positive macrophages that appeared to be stromal keratocytes by light microscopy. Despite the presence of chronic inflammation in both patients, no stromal lymphocytes were seen in one patient and a sparse lymphocytic infiltrate was seen in the other patient. Electron microscopy confirmed the presence of macrophages, neutrophils, and Acanthamoeba organisms in these two patients.

Nocardia asteroides keratitis. A case report.

An 11-year-old girl developed a corneal ulcer five days after sustaining a corneal abrasion from a fishline sinker. After more than three weeks, the epithelial defect had closed, but superficial stromal opacities in a ring-like distribution had not cleared on topical gentamicin, prednisolone 1% and atropine. Several scrapings disclosed the presence of branching hyphae on smear, eventually identified as Nocardia asteroides by culture. Although sensitivity studies suggested that subconjunctival ampicillin and hourly sodium sulphacetamide would constitute effective treatment, resolution was only partial on this regimen. Only when penicillin G drops were added did the cornea clear maximally and the epithelium heal.

The 1998 Castroviejo Lecture. New strategies in the treatment of dry-eye states.

PURPOSE: To review developments in dry-eye research leading to new therapeutic possibilities and to suggest a prioritizing schema. METHODS: New development in our understanding of the pathogenesis, diagnoses, and treatment of dry-eye states have been reviewed along with the possible impact on new therapeutic approaches. RESULTS: A variety of approaches to the pathogenesis and degrees of dry-eye states have emerged, giving rise to significant new approaches to the treatment of these disorders. CONCLUSION: There are now new treatment possibilities. Ranking their development based on their fundamental reversal of disease mechanisms seems a reasonable approach with early therapeutic pay-off.

Is the dry eye contact lens wearer at risk? Yes.

Numerous studies have demonstrated that patients with dry eyes have a compromised ocular surface. Furthermore, these patients suffer deficiencies of various surface defense mechanisms, such as tear volume, tear components (lysozyme, lactoferrin, and beta-lysin), the mucin network, cellular exfoliation, and subsurface immune secretions. When such individuals wear contact lenses (CLs), a special set of circumstances arises that increases the risk of ocular infection. The risk is greatest if the lenses are soft and, therefore, provide for little tear exchange beneath their surface. Under such circumstances, limited tear flow allows for a greater buildup of lens deposits and metabolic wastes, while permitting increased tear evaporation from the lens surface. The pathogenesis of infection is attributed to various mechanisms, including decreased tear flow beneath the lens, decreased tear components, stagnation of the mucin network, changes in surface cell exfoliation, and putative changes in the subsurface immune secretory system. Dry eye patients who wear soft CLs also run a greater risk of bacterial conjunctivitis, blepharitis, and sterile corneal infiltrates.

Corneal rim cultures.

We performed a retrospective analysis of 291 consecutive scleral rim cultures, taken at the time of corneal transplantation, from 1981 to 1986. There were 82 positive cultures (39%), and the most common pathogen was Staphylococcus epidermidis, with 24 positive cultures (30%). Ten of these (42%) were resistant to gentamycin. There were no cases of endophthalmitis or other infections in the immediate postoperative period. We also found 15 positive cultures of Streptococcus viridans. Of these, 13 (87%) were resistant to gentamycin but sensitive to most other antibiotics. Even though endophthalmitis is rare following penetrating keratoplasty, the emergence of resistant strains of Streptococcus viridans and Staphylococcus epidermidis suggests that eyebanks need to consider the addition of a second antibiotic to their MK medium.

Vortex keratopathy of the corneal graft.

We examined the surface epithelium of 30 eyes with color specular microscopy at 3-month intervals 1-18 months following penetrating keratoplasty. At least three examinations were performed on most eyes. We found a vortex keratopathy to be present in 70% of these eyes. In nine eyes, this vortex pattern was present at every examination, and in 12 eyes, it was present at some examinations and not at others. There was no vortex pattern seen at any examination in nine eyes. We also found alterations in the normal epithelial morphology around sutures and at the wound margin, with palisading parallel to the sutures and perpendicular to the wound edge. This altered morphology was also demonstrated by digitization of cells for shape and size, which showed significant differences compared with normals. We conclude that the morphology of the epithelial cells on the surface of the cornea remains abnormal for up to 18 months following penetrating keratoplasty.

Tandem-scanning (confocal) microscopy of the full-thickness cornea.

We have utilized a radically new type of optical scanning microscope to study the full-thickness morphology of the intact cornea in an excised human eye bank eye and in freshly sacrificed rabbit eyes in situ. This technology enables one to study corneal morphology layer by layer in extremely thin sections, only disturbing the tissue with an applanating tip. We have demonstrated the cells of the corneal surface, subsurface cells, the topography of Bowman's membrane, corneal lamellae, stromal keratocytes, and the corneal endothelium. The application of this technology lends itself to the in vivo examination of the human cornea. This should aid us greatly in the study of normal morphology, disease states, and the reaction of the cornea in wound healing.