Evaluation of Efficacy and Safety of Ciprofloxacin Ophthalmic Solution versus Chloramphenicol

The results of this clinical study demonstrate that ciprofloxacin ophthalmic solution 0.3% is as safe and as effective as 0.5% chloramphenicol ophthalmic solution in the treatment of conjunctivitis and blepharitis of bacterial aetiology. Both agents achieved microbiological improvement rates in excess of 90% after 1 week's treatment. On ciprofloxacin 93.5% of patients were judged clinically cured or improved versus 84.6% on chloramphenicol after 1 week. There were no serious adverse affects. One patient in each group suffered drug-related side-effects (chemosis, erythema) which resolved on discontinuation or changing of therapy. Cirpofloxacin is not associated with the rare, but serious, side effect of aplastic anaemia which is associated with chloramphenicol use. On the evidence of this study ciprofloxacin would appear to be an appropriate agent for general use as a topical ophthalmic formulation.

Topical Ciprofloxacin in the Treatment of Blepharitis and Blepharoconjunctivitis

An international multicentre study assessed the clinical and antibacterial efficacy of a new topical ophthalmic formulation of the quinolone antimicrobial agent ciprofloxacin and compared it with that of tobramycin ophthalmic solution in patients with blepharitis and blepharoconjunctivitis. The study consisted of a randomised double-masked between-group evaluation of 464 patients, 230 of whom were treated with ciprofloxacin and 234 with tobramycin. There was qualitative and quantitative bacteriology, and clinical assessment of ocular symptoms and signs before and after a seven-day course of treatment. Bacteriological cultures demonstrated eradication or reduction of potentially pathogenic bacteria in 93.7% of eyes (ciprofloxacin) versus 88.9% of eyes (tobramycin), seven days after starting treatment. Clinically more than 80% of patients in both treatment groups were cured or improved after seven days. No statistically significant differences were observed between the two treatment groups. No serious side-effects were observed after use of either antimicrobial agent. Ciprofloxacin ophthalmic solution appears safe and effective. The spectrum of activity and clinical efficacy of this new formulation are discussed in comparison with currently used antimicrobial agents.

Randomised Double-Masked Trial of Lodoxamide and Sodium Cromoglycate in Allergic Eye Disease

135 patients were entered into a 28-day randomized double-masked multicentre study comparing the efficacy and short-term safety of lodoxamide 0.1% ophthalmic solution (Alomide--Alcon Laboratories), a mast cell stabilizer, with sodium cromoglycate 2% ophthalmic solution (Opticrom--Fisons Pharmaceuticals) in the treatment of allergic eye disease. Patients given lodoxamide 0.1% showed a significantly more rapid and greater improvement in their signs and symptoms of allergic eye disease than patients given sodium cromoglycate 2%. Both treatments were found to be safe, and side-effect profiles were comparable between the two treatment groups, although the overall incidence of side-effects in this study was found to be less frequent in the lodoxamide-treated group.

Group Comparative Trial of 2% Nedocromil Sodium with Placebo in the Treatment of Seasonal Allergic Conjunctivitis

A double blind group comparative trial comparing 2% nedocromil sodium with placebo in treating seasonal allergic conjunctivitis over a four week period is reported. Sixty-four patients were analysed. During the period of peak pollen challenge, statistically significant differences in favour of nedocromil sodium for itching and soreness were demonstrated. During a longer period of a less high pollen count, a significant difference in favour of nedocromil sodium was shown only for the symptom of soreness.

Localised Wegener's Granulomatosis Presenting as an Orbital Pseudotumour with Extension into the Posterior Cranial Fossa

Pseudotumour has rarely been reported to invade the intracranial cavity. We present a case of pseudotumour which extended intra-cranially into the posterior cranial fossa. The patient had circulating antineutrophil cytoplasmic antibodies in titres diagnostic for Wegener's granulomatosis. In the absence of clinical renal or respiratory tract disease, the case may represent a newly recognized sub-type of “localised” Wegener's granulomatosis.

Isolated human and rabbit eye: Models of corneal toxicity

Human and rabbit isolated eyes were compared, not in order to propose yet another test, but to explore the boundaries of the rabbit isolated cornea as a model for primary damage to human cornea. Changes in corneal thickness and in epithelial morphology were followed on recovery from cold-induced oedema and after exposure to the test chemicals. There was no statistical difference between control human and rabbit eyes in recovery from severe oedema. The effects of exposure to allyl alcohol, Arlagard E, NaOH (1 N), NaCl, sodium lauryl sulphate (2%) and Tween-20 were similar in human and rabbit eyes. Acetone, ethanol and glycerol had opposed-sign effects on corneal thickness in human and rabbit. From the small number of substances tested it can be concluded qualitatively that stored rabbit eyes behave in a manner similar to freshly isolated rabbit eyes, and that substances in which penetration depends on surface properties of the cornea may have species-specific effects.

Comparison of a non-preserved 0.1% T-Gel eye gel (single dose unit) with a preserved 0.1% T-Gel eye gel (multidose) in ocular hypertension and glaucomatous patients

AIM

This comparative, open design, phase III study was to assess the non-inferiority of the non-preserved T-Gel 0.1% single dose unit (SDU) versus its preserved multidose (MD) reference.

METHODS

175 patients with bilateral POAG or OHT were randomised: 87 patients were to receive one drop daily of T-Gel 0.1% MD and 88 patients were to receive one drop daily of T-Gel 0.1% SDU, for a treatment period of 12 weeks. The primary efficacy variable was the change in intraocular pressure (IOP) in the worse eye between the baseline and the last assessment. Subjective and objective ocular signs as well as adverse events were recorded for safety. Global tolerance was assessed by the investigator and by the patient.

RESULTS

The mean percentage reduction from baseline IOP was 24% for both treatments groups, which was consistent with previous studies. The safety results were comparable in both treatment groups. Because of gel formulation, mild short lasting episodes of blurred vision occurred for about 20% of patients. The global tolerance assessment reported that both treatments were well tolerated.

CONCLUSION

The overall study results demonstrated that T-Gel 0.1% SDU is not inferior to T-Gel 0.1% MD.

Development of organised conjunctival leucocyte aggregates after corneal transplantation in rats

AIM

To investigate the development of lymphoid aggregates in the conjunctiva after corneal transplantation in rats.

METHODS

LEW or PVG strain corneas were transplanted orthotopically to PVG rats. Cornea and conjunctiva were examined clinically for up to 42 days. Eyes were removed with attached conjunctiva on days 10 and 15 after transplantation (before and during rejection), together with normal eyes, fixed, paraffin embedded, and examined immunohistochemically.

RESULTS

Clinically, the temporal half of the upper palpebral conjunctiva of recipients of 10/19 allografts and 1/10 isografts developed pronounced swelling, correlating with inflammation and rejection. Histologically, the swelling comprised leucocytic aggregates with an altered overlying epithelium. Aggregates contained granulocytes, macrophages, and cells expressing major histocompatibility complex (MHC) class II, CD4, and CD8, all more numerous in allograft associated conjunctiva. Class II+ cells were more abundant at the surface, whereas macrophages and T cells were more numerous in the deeper stroma. There were few B cells. There was greater CD54 expression by vascular endothelium in allograft associated aggregates. Cells expressing TNFalpha and IFNgamma but not IL1beta were present in stromal and superficial areas.

CONCLUSIONS

Corneal transplantation in rats induces the development of organised conjunctival leucocytic aggregates in a fixed location that are significantly more pronounced in recipients of allografts compared with isografts and show characteristics of a Th1 type immune response. These aggregates have characteristics of conjunctiva associated lymphoid tissue and may be sites of presentation of graft antigens and lymphocyte proliferation at the ocular surface.

Clinical evaluation of twice-daily emedastine 0.05% eye drops (Emadine eye drops) versus levocabastine 0.05% eye drops in patients with allergic conjunctivitis

PURPOSE

The efficacy and safety of emedastine 0.05% eye drops (Emadine; Alcon Laboratories, Inc, Fort Worth, Texas), a new H(1) antagonist, were studied in comparison to levocabastine 0.05% eye drops (Livostin; Janssen-Cilag N V, Berchem, Belgium) during a twice-daily treatment schedule for 6 weeks in adult and pediatric patients with seasonal allergic conjunctivitis.

METHODS

In a prospective, multicenter, randomized, double-masked, parallel group study, 222 patients with allergic conjunctivitis were randomized (221 received treatment) to either emedastine or levocabastine, instilled twice daily for 6 weeks. Patient diaries were completed four times daily (before the morning and evening instillations, at noon, and in the afternoon), and clinical examinations were conducted at regular intervals. Primary efficacy variables of ocular redness and itching and secondary efficacy variables of chemosis, eyelid swelling, patient diary data, and physician's global assessment were analyzed.

RESULTS

Both emedastine and levocabastine produced a statistically significant (P =.0001) reduction in itching and redness within 5 minutes of the first instillation. All signs and symptoms improved progressively over the 6-week treatment period. After 7 days of use, and throughout the remainder of the study, emedastine was statistically superior to levocabastine (P <.006) in preventing and alleviating the signs and symptoms (itching, redness, chemosis, and eyelid swelling) of allergic conjunctivitis.

CONCLUSIONS

Emedastine 0.05% eye drops administered twice daily are more efficacious than levocabastine 0.05% eye drops in the prevention and treatment of the signs and symptoms of allergic conjunctivitis in adults and children of 4 years and above. Both emedastine 0.05% eye drops and levocabastine 0.05% eye drops were well tolerated.

Tear film MMP accumulation and corneal disease

BACKGROUND/AIMS

Matrix metalloproteinases (MMPs) accumulate in the tears of patients with active peripheral ulcerative keratitis (PUK) but it is unknown whether these enzymes have a central role in disease progression. The aims of the present investigation were to determine the source of these enzymes and to ascertain whether their accumulation in tears is a phenomenon specific to PUK or a general feature of other anterior segment diseases.

METHODS

The experimental samples were obtained from the culture media of conjunctival and corneal epithelial cells, from fractionated blood plasma and leucocytes of healthy subjects and patients with rheumatoid arthritis, and from the tears of healthy subjects and patients with a variety of anterior segment diseases. The MMPs of all samples were visualised by zymography and tear samples were assayed using nitrophenol acetate and an MMP-9 susceptible quenched fluorescent peptide as substrate.

RESULTS

The major MMPs that accumulate in the tears of patients with rheumatoid arthritis with active ocular disease are MMP-9 and a species of M(r) 116,000. By comparing the zymographic activity profiles of the gelatinases present in the samples obtained, it was deduced that the main source of these MMPs was granulocytes. Their accumulation in tears was not unique to patients with PUK; detectable amounts of the enzymes also occurred in the tears of patients with keratoconus with associated atopic disease, patients undergoing treatment for herpetic eye disease, and patients with systemic and non-systemic dry eye disease.

CONCLUSION

The MMPs that accumulate in tears are mainly derived from granulocytes. This may be effected by autoimmune diseases that involve ocular tissue or by ocular diseases that induce an inflammatory response.

Cytokine production in a murine model of recurrent herpetic stromal keratitis

PURPOSE

To determine the pattern of cytokine production in the cornea and its relationship with viral antigens, in our murine model of recurrent ocular herpes simplex virus (HSV)-1 infection.

METHODS

Six weeks after corneal inoculation with HSV-1, the eyes of latently infected and control mice were UV irradiated and examined for signs of disease and viral reactivation. The eyes of five mice with recurrent stromal disease and two controls were processed for immunohistochemistry on days 4, 7, 10, and 14 after irradiation. Sections were double stained for viral antigens and one of the following cytokines: interleukin (IL)-1ss, IL-2, IL-4, IL-6, IL-10, IL-12, and interferon (IFN)-gamma.

RESULTS

Fifty percent of mice showed signs of recurrent stromal disease, the severity of which peaked on day 10 after UV irradiation. There was a large cellular infiltrate in the stroma of all the corneas with recurrent disease and the predominant cytokines were IL-1ss, IL-6, IL-10, IL-12, and IFN-gamma, all present in large numbers of cells on the days studied. There were very few cells producing IL-2 and IL-4. Control eyes had no significant cytokine-producing cells in the stroma.

CONCLUSIONS

These observations suggest that recurrent herpetic stromal keratitis (HSK) may not be characterized by a classic T-helper (Th)1 or Th2 response. However, the large number of IFN-gamma(+) and IL-12(+) cells and the relative absence of IL-4 favors a Th1 response, and despite the numerous IL-10(+) cells, the overall balance of cytokine production appears to be proinflammatory.

Matrix metalloproteinase 2 activation in cultured corneas

PURPOSE

Corneas that are maintained in tissue culture medium shed their epithelial cells and repopulation following graft surgery is an essential facet of the healing process. Failure to do so may be a result of structural damage to the epithelial basement membrane of a donor cornea. The purpose of the present investigation was to ascertain whether MMP-2, the matrix metalloproteinase produced by corneal keratocytes, may be activated during storage and hence cleave the type IV collagen component of the epithelial cell basement membrane.

METHODS

Fresh and transplant rejected corneas that had been stored in culture medium for varying time periods and of known donor age were collected. The soluble protein fractions of these corneas were obtained. Their MMP-2 proteins were visualised by zymography on SDS gelatin polyacrylamide gels and assayed for activity against nitrophenyl acetate and denatured [(3)H]type I collagen.

RESULTS

The stromal tissue of fresh, normal corneas produced inactive MMP-2 of M(r) 66,000. Although the cultured corneas did not up-regulate MMP-2 production, they contained additional MMP-2 activities of M(r) 62,000 and M(r) 43,000. The appearance of these additional MMP-2 activities correlated with corneal culture time but not donor age. The ability to cleave denatured [(3)H]type I collagen correlated with the appearance of the M(r) 43,000 activity but not the M(r) 62,000 activity.

CONCLUSION

Activated MMP-2 is produced in cultured corneas. For this reason the corneas donated for all graft procedures should not be held in culture medium for periods exceeding 4 weeks.

The control of matrix metalloproteinase-2 expression in normal and keratoconic corneal keratocyte cultures

PURPOSE

Early phase keratoconic corneas and their cultured keratocytes abnormally produce the Mr 62,000 form of the matrix metalloproteinase-2 (MMP-2). It is known that platelet derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta) are involved in the regulation of MMP activity and tissue inhibitor of metalloproteinase (TIMP) production in non-ocular tissues. The purpose of this enquiry was to determine whether these growth factors also play a role in the activity and/or production of corneal MMP-2 and TIMP, and whether their activity could account for the existence of the Mr 62,000 form of MMP-2 in keratoconic corneas.

METHODS

Confluent cultures of normal and early-phase keratoconic corneal keratocytes were established and incubated in serum-free media in the presence or absence of PDGF and TGF-beta. The proteins secreted by these cells over periods of 7 days were harvested for analysis. The total protein produced was determined spectrophotometrically. MMP-2 was visualised by SDS-gelatin polyacrylamide gel electrophoresis and assayed using radiolabelled type IV collagen as substrate. The enzyme inhibitors, TIMP-1 and TIMP-2, were quantified by dot blot immunoassay.

RESULTS

The addition of PDGF or TGF-beta to the culture medium of keratoconic corneal keratocytes had no significant effect on overall protein production, MMP-2 activity or on the amounts of TIMP- 1 and TIMP-2 secreted. These observations also applied to normal corneal keratocytes, with the exception that PDGF induced expression of the Mr 62,000 species of MMP-2.

CONCLUSIONS

PDGF may be involved in the production of the Mr 62,000 species of MMP-2 that is abnormally produced by early-phase keratoconic corneal keratocytes.

Matrix metalloproteinase 2: involvement in keratoconus

PURPOSE

The activation of matrix metalloproteinase-2 (MMP-2) is postulated to be a crucial pathogenic factor behind progressive and chronic diseases in which basement membranes are disrupted. An ocular example is keratoconus. The purpose of the present enquiry was therefore to investigate and compare the activities of the MMP-2 secreted by keratocytes of normal and keratoconic corneas.

METHODS

The spectrum of MMP-2 activities secreted by cultures of keratocytes derived from normal and keratoconic corneas was analysed by zymography. Subsequently, selected preparations were assayed for peptidase activity, using Type I, Type III, Type IV and Type V collagen as substrate, under native conditions and after treatment with a variety of putative activating reagents.

RESULTS

Although MMP-2 of Mr 65,000 on SDS gelatin polyacrylamide gels is the major protease secreted by keratocytes of normal corneas, the keratocytes of early-phase keratoconic corneas secrete an additional zymographic activity of Mr 61,000. From their N-terminal amino acid sequences, both these proteins were shown to be conformers of proMMP-2. Treatment with SDS followed by protein fractionation was required to achieve in vitro activation of the MMP-2 secreted by normal corneal keratocytes. Treatment with SDS alone partially activated the enzyme produced by early-phase keratoconic corneal keratocytes. This procedure and autocatalysis, yielded an enzyme of Mr 43,000 that selectively hydrolysed Type IV and denatured Type 1 collagen.

CONCLUSIONS

The zymographic gelatinase activities of apparent Mr 65,000 and 61,000 are conformers of corneal proMMP-2. Activated enzyme, of Mr 43,000, is more readily generated from protein preparations of the culture media of early phase keratoconic corneal keratocytes than from protein preparations of the culture media of normal corneal keratocytes.

Human herpesviruses in the cornea

AIMS

To determine the sensitivity and specificity of culture, immunohistochemistry (IHC), the polymerase chain reaction (PCR), and in situ hybridisation (ISH) for detecting herpes simplex virus (HSV-1) in the cornea of patients undergoing penetrating keratoplasty. To compare the incidence of HSV-1 in the cornea with that of varicella zoster virus (VZV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV).

METHODS

The corneas of 110 patients, 52 with a documented history of herpes keratitis (HSK) and 58 with non-herpetic corneal disease, were investigated using IHC, PCR, ISH, and culture.

RESULTS

HSV-1 DNA and antigen were detected in 82% and 74% respectively, of corneas of patients with HSK and in 22% and 15% of corneas of patients with no history of HSK. The sensitivity of PCR and IHC was 82% and 74% with a specificity of 78% and 85%, respectively. HSV-1 DNA and antigen were found more frequently and in increased amounts in corneas of patients with a short interval between their last attack of HSK and surgery. There was a good correlation between PCR and IHC in 71%. HSV-1 was isolated by culture in 2%. Latency associated transcripts were not detected using ISH. Evidence of VZV DNA or antigen was found significantly more frequently in the corneas of patients with a history of HSK (p<0.001). No evidence of EBV or CMV was found in any cornea.

CONCLUSIONS

PCR and IHC are both sensitive for the detection of HSV-1 in the cornea. A combination of PCR and IHC increases the specificity for the diagnosis of HSK to 97%. HSV-1 appears to be slowly removed from the cornea. VZV and HSV-1 may co-infect the cornea.

The Bristol shared care glaucoma study: outcome at follow up at 2 years

AIM

To examine the outcome of care for patients with glaucoma followed up by the hospital eye service compared with those followed up by community optometrists.

METHODS

A randomised study with patients allocated to follow up by the hospital eye service or community optometrists was carried out in the former county of Avon in south west England. 403 patients with established or suspected primary open angle glaucoma attending Bristol Eye Hospital and meeting defined inclusion and exclusion criteria were studied. The mean number of missed points on visual field testing in the better eye (using a "better/worse" eye analysis) in each group were measured. The visual field was measured using the Henson semiautomated central field analyser (CFA 3000). Measurements were made by the research team on all patients at baseline before randomisation and again 2 years after randomisation. The mean number of missed points on visual field testing in the worse eye, mean intraocular pressure (mm Hg), and cup disc ratio using a "better/worse" eye analysis in each group at 2 years were also measured. Measurements were made by the research team on all patients at baseline before randomisation and again 2 years after randomisation. An analysis of covariance comparing method of follow up taking into account baseline measurements of outcome variables was carried out. Additional control was considered for age, sex, diagnostic group (glaucoma suspect/established primary open angle glaucoma), and treatment (any/none).

RESULTS

From examination of patient notes, 2780 patients with established or suspected glaucoma were identified. Of these, 752 (27.1%) fulfilled the entry criteria. For hospital and community follow up group respectively, mean number of missed points on visual field testing at 2 year follow up for better eye was 7.9 points and 6.8 points; for the worse eye 20.2 points and 18.4 points. Similarly, intraocular pressure was 19.3 mm Hg and 19.3 mm Hg (better eye), and 19.1 mm Hg and 19.0 mm Hg (worse eye); cup disc ratio at 2 year follow up was 0.72 and 0.72 (better eye), and 0.74 and 0.74 for hospital and community follow up group respectively. No significant differences in any of the key visual variables were found between the two groups before or after adjusting for baseline values and age, sex, treatment, and type of glaucoma.

CONCLUSIONS

It is feasible to set and run shared care schemes for a proportion of patients with suspected and established glaucoma using community optometrists. After 2 years (a relatively short time in the life of a patient with glaucoma), there were no marked or statistically significant differences in outcome between patients followed up in the hospital eye service or by community optometrists. Decisions to implement such schemes need to be based on careful consideration of the costs of such schemes and local circumstances, including geographical access and the current organisation of glaucoma care within the hospital eye service.

Age related changes in the non-collagenous components of the extracellular matrix of the human lamina cribrosa

AIMS

To investigate age related alterations in the non-collagenous components of the human lamina cribrosa.

METHODS

Fibronectin, elastin, and glial fibrillary acidic protein (GFAP) staining were assessed in young and old laminae cribrosae. An age range (7 days to 96 years) of human laminae cribrosae were analysed for lipid content (n=9), cellularity (n=28), total sulphated glycosaminoglycans (n=28), elastin content (n=9), and water content (n=56), using chloroform-methanol extraction, fluorimetry, the dimethylmethylene blue assay, and ion exchange chromatography, respectively.

RESULTS

Qualitatively, an increase in elastin and a decrease in fibronectin and GFAP were demonstrated when young tissue was compared with the elderly. Biochemical analysis of the ageing human lamina cribrosa demonstrated that elastin content increased from 8% to 28% dry tissue weight, total sulphated glycosaminoglycans decreased, and lipid content decreased from 45% to 25%. There were no significant changes in total cellularity or water content.

CONCLUSION

These alterations in composition may be indicative of the metabolic state of the lamina cribrosa as it ages, and may contribute to changes in mechanical integrity. Such changes may be implicated in the susceptibility of the elderly lamina cribrosa and also its response to glaucomatous optic neuropathy.

Age related compliance of the lamina cribrosa in human eyes

AIMS

To investigate changes in the mechanical compliance of ex vivo human lamina cribrosa with age.

METHODS

A laser scanning confocal microscope was used to image the surface of the fluorescently labelled lamina cribrosa in cadaver eyes. A method was developed to determine changes in the volume and strain of the lamina cribrosa created by increases in pressure. The ability of the lamina cribrosa to reverse its deformation on removal of pressure was also measured.

RESULTS

Volume and strain measurements both demonstrated that the lamina cribrosa increased in stiffness with age and the level of pressure applied. The ability of the lamina cribrosa to regain its original shape and size on removal of pressure appeared to decrease with age, demonstrating an age related decrease in resilience of the lamina cribrosa.

CONCLUSIONS

The mechanical compliance of the human lamina cribrosa decreased with age. Misalignment of compliant cribriform plates in a young eye may exert a lesser stress on nerve axons, than that exerted by the rigid plates of an elderly lamina cribrosa. The resilience of the lamina cribrosa also decreased with age, suggesting an increased susceptibility to plastic flow and permanent deformation. Such changes may be of importance in the explanation of age related optic neuropathy in primary open angle glaucoma.

Nedocromil sodium in two models of conjunctival immediate hypersensitivity

The effects of intravenous administration of nedocromil sodium were investigated in active and passive models of conjunctival immediate hypersensitivity in rats. In the active sensitization model, animals were immunized with ovalbumin 21 days prior to ocular instillation of a solution containing ovalbumin. Nedocromil sodium administered prior to antigen challenge significantly inhibited emergence of conjunctival edema and erythema (P < .05) and reduced mast cell degranulation (P < .02). In the passive-sensitization model, the conjunctiva in one eye was injected with ovalbumin antiserum 48 hours prior to intravenous administration of ovalbumin. Nedocromil sodium administered prior to antigen challenge significantly and dose-dependently reduced appearance of the signs of conjunctivitis (P < .01) as well as vascular leakage (P < .05). These data indicate that intravenous nedocromil sodium is effective in animal models of allergic conjunctivitis and may have potential for wider therapeutic application. These data are also consistent with results of clinical studies in which nedocromil sodium relieved symptoms of allergic conjunctivitis and further support a role for nedocromil sodium in the prevention of allergic conjunctivitis.

Role of ocular matrix metalloproteinases in peripheral ulcerative keratitis

AIM

Peripheral ulcerative keratitis (PUK) is an ocular manifestation of rheumatoid arthritis and other similar systemic diseases. The purpose of this inquiry was to investigate the involvement of matrix metalloproteinases (MMPs) in the induction and/or maintenance of PUK.

METHODS

Substrate gel electrophoresis was used to characterise the MMP activities secreted by primary cultures of keratocytes derived from normal and perforated pathological corneal specimens, and those present in tears of normal subjects and patients with PUK. Substrate specificity and the in vivo activity status of the secreted MMPs was assessed by SDS-polyacrylamide gel electrophoresis of standard collagens incubated in the presence or absence of the various enzyme preparations.

RESULTS

In addition to MMP-2 of M(r) 66,000, cultured keratocytes derived from perforated corneas of patients with PUK abnormally produce the MMP-2 of apparent M(r) 62,000. Other MMPs and in particular MMP-9 of M(r) 92,000, also occur in the tears of these patients. Their visualisation on substrate polyacrylamide gels correlated with clinical manifestations of disease activity; during periods of disease quiescence they were barely detectable. The steroid prednisolone, frequently used in systemic therapy, had no effect on the in vitro activity of MMP-2, or on its production by cultured corneal keratocytes. Although the in vitro activity of MMP-2 was inhibited by both Cu(2+) and Zn(2+), Cu(2+) apparently induced the keratocytes to produce activated enzyme and Zn(2+) irreversibly inhibited their production of MMP-2.

CONCLUSION

Overexpression of corneal MMP-2 and tear film MMP-9 are characteristic features of patients with PUK and their activation may be a crucial facet of disease initiation or progression. Although effective in systemic therapy for PUK, prednisolone had no direct control over corneal MMP-2 production or activity. Zn(2+) on the other hand inhibited both MMP-2 production and MMP-2 activity and may, therefore, be of therapeutic value if suitably formulated and used in conjunction with systemic steroid treatment.

The Bristol Shared Care Glaucoma Study: reliability of community optometric and hospital eye service test measures

BACKGROUND/AIMS

Primary open angle glaucoma patients and glaucoma suspects make up a considerable proportion of outpatient ophthalmological attendances and require lifelong review. Community optometrists can be suitably trained for assessment of glaucoma. This randomised controlled trial aims to assess the ability of community optometrists in the monitoring of this group of patients.

METHODS

Measures of cup to disc ratio, visual field score, and intraocular pressure were taken by community optometrists, the hospital eye service and a research clinic reference "gold" standard in 405 stable glaucoma patients and ocular hypertensives. Agreement between and within the three centres was assessed using mean differences and intraclass correlation coefficients. Tolerance limits for a change in status at the level of individual pairs of measurements were also calculated.

RESULTS

Compared with a research clinic reference standard, measurements made by community optometrists and those made in the routine hospital eye service were similar. Mean measurement differences and variability were similar across all three groups compared for each of the test variables (IOP, cup to disc ratio, and visual field). Overall, the visual field was found to be the most reliable measurement and the cup to disc ratio the least.

CONCLUSIONS

Trained community optometrists are able to make reliable measurements of the factors important in the assessment of glaucoma patients and glaucoma suspects. This clinical ability should allow those optometrists with appropriate training to play a role in the monitoring of suitable patients.

Reactivation of herpes simplex virus type 1 in the mouse trigeminal ganglion: an in vivo study of virus antigen and cytokines

Reactivation of herpes simplex virus type 1 (HSV-1) in the trigeminal ganglion (TG) was induced by UV irradiation of the corneas of latently infected mice. Immunocytochemistry was used to monitor the dynamics of cytokine (interleukin-2 [IL-2], IL-4, IL-6, IL-10, gamma interferon [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]) and viral antigen production in the TG and the adjacent central nervous system on days 1 to 4, 6, 7, and 10 after irradiation. UV irradiation induced increased expression of IL-6 and TNF-alpha from satellite cells in uninfected TG. In latently infected TG, prior to reactivation, all satellite cells were TNF-alpha+ and most were also IL-6(+). Reactivation, evidenced by HSV-1 antigens and/or infiltrating immune cells, occurred in 28 of 45 (62%) TG samples. Viral antigens were present in the TG in neurons, often disintegrating on days 2 to 6 after irradiation. Infected neurons were usually surrounded by satellite cells and the foci of immune cells producing TNF-alpha and/or IL-6. IL-4(+) cells were detected as early as day 3 and were more numerous by day 10 (a very few IL-2(+) and/or IFN-gamma+ cells were seen at this time). No IL-10 was detected at any time. Our observations indicate that UV irradiation of the cornea may modulate cytokine production by satellite cells. We confirm that neurons are the site of reactivation and that they probably do not survive this event. The predominance of TNF-alpha and IL-6 following reactivation parallels primary infection in the TG and suggests a role in viral clearance. The presence of Th2-type cytokines (IL-4 and IL-6) indicates a role for antibody. Thus, several clearance mechanisms may be at work.

An improved method for examining the corneal endothelium during graft rejection in the rat

An improved method of removing rat corneal endothelial sheets for study of endothelial pathology is described. The method was validated by examining morphological changes and changes in expression of major histocompatibility complex (MHC) and intercellular adhesion molecule (ICAM)-1 on endothelium undergoing immunological rejection. PVG strain rats received LEW strain corneal transplants or corneal isografts. Just prior to and during graft rejection, animals were killed, together with a group of untreated animals. The corneal stroma was injected with dispase or PBS, the cornea was carefully removed, fixed in acetone and the endothelium was gently peeled off and flattened on to a glass slide. Morphological changes, together with MHC class I, class II and ICAM-1 expression were visualised by immuno-histochemical staining and quantified by image analysis. Near complete endothelial sheets were obtained by this method. Because of the thin cell layer, there was minimal background staining, permitting rejection-associated changes to be clearly seen. MHC class I expression on normal endothelium was low and not significantly increased on endothelial cells of allografts at the time of rejection compared with controls (P = 0.1). MHC class II and ICAM-1 were induced de novo, expression being significantly higher on allografts than on isografts (P = 0.004 for MHC class II and P = 0.01 for ICAM-1). MHC class I and II and ICAM-1 were expressed on many infiltrating cells. Thus, this preparation method permits clear identification of the distribution and morphology of infiltrating cells and other mediators of the immune response in the entire donor endothelium. It confirms that MHC class I expression is low during rejection, while MHC class II and ICAM-I are induced de novo and strongly expressed.

Combined interrupted and continuous versus single continuous adjustable suturing in penetrating keratoplasty: a prospective, randomized study of induced astigmatism during the first postoperative year

OBJECTIVE

To compare postoperative astigmatism induced by two different suturing techniques in penetrating keratoplasty (PKP).

DESIGN

A monocenter, prospective, randomized clinical trial with a longitudinal 1-year follow-up.

PARTICIPANTS

A total of 95 eyes undergoing PKP were randomized into 2 groups. Of these, 51 eyes were allocated to the combined interrupted and continuous suturing group (ICS) and 44 eyes to the single continuous adjustable suturing (SCAS) group.

INTERVENTION

In the ICS group, suturing was with a combination of 12 interrupted 10-0 nylon and 1 continuous 11-0 nylon sutures. Eyes in the SCAS group had been sutured with a single running 24-bite 10-0 nylon. Selective suture removal started no earlier than 10 weeks after surgery; suture adjustment could start as soon as possible after surgery.

MAIN OUTCOME MEASURES

Astigmatism was measured by topography, keratometry, and refraction at 3-, 6-, 9-, and 12-month postoperative intervals.

RESULTS

The difference in mean time of suture manipulation between groups was significant (P = 0.0001), with the SCAS starting earlier. A significant decrease in astigmatism occurred by either interrupted suture removal (6.69 +/- 3.11 diopter [D] before to 4.76 +/- 2.99 D after, P = 0.0002) or suture adjustment (7.18 +/- 3.12 D before to 4.46 +/- 3.24 D after, P = 0.0001). However, the net astigmatic reduction in the SCAS group was not significantly greater (P = 0.250) than in the ICS group. Vector change was 7.40 +/- 4.17 D and 6.28 +/- 4.14 D for SCAS and ICS, respectively (P = 0.13). At no interval (3, 6, 9, or 12 months) was there significant difference in astigmatism between the two groups. Refractive astigmatism (cyl, D) at 1 year was 2.66 +/- 1.70 for the ICS and 3.12 +/- 2.62 for the SCAS, but there was no significant treatment effect (P = 0.945). Furthermore, 66% of the ICS eyes and 58% of the SCAS eyes (P = 0.295) were within the astigmatic target of the study (<3.5 D).

CONCLUSIONS

Postkeratoplasty astigmatism can be decreased similarly with either adjustment of a single running suture or selective removal of interrupted sutures. No advantage of the SCAS over ICS in terms of fewer manipulations or less astigmatism was seen as suggested previously.

Surgical control of late postkeratoplasty astigmatism with or without the use of computerized video keratography: a prospective, randomized study

OBJECTIVE

To assess the effectiveness of computerized videokeratography (CVK) in refining the surgical design and in improving predictability of surgical correction of postkeratoplasty astigmatism.

DESIGN

A prospective, controlled, randomized, clinical trial.

PARTICIPANTS

A total of 31 postkeratoplasty eyes, divided into 2 groups (group A, 16 eyes; group B, 15 eyes), with more than 4 diopters (D) of disabling astigmatism were studied.

INTERVENTION

All eyes were treated with a combination of arcuate relaxing incisions and compression sutures. The surgical plan in group A was based on topographic information, whereas in the control group B, the surgical plan was based on information obtained by refraction and keratometry alone.

MAIN OUTCOME MEASURES

Change in the surgical plan induced by the CVK information, astigmatism, topographic patterns, and factors associated with outcome were measured.

RESULTS

In all 16 cases of group A, the use of CVK changed some aspect of the surgical plan. At 12 months after surgery, both groups showed a significant net reduction (P = 0.001) of baseline astigmatism. However, the reduction (47% and 41 % for groups A and B, respectively) did not differ significantly between the two groups. The topographic astigmatism at 12 months measured 4.24 +/- 0.71 D in group A and 5.60 +/- 0.51 D in group B (P = 0.139). Significant differences between the two groups at 12 months were seen only for keratometric astigmatism (3.60 +/- 0.81 D in group A vs. 5.77 +/- 0.52 D in group B, P = 0.035) and refractive astigmatism (2.34 +/- 0.37 D in group A vs. 4.88 +/- 0.52 D in group B, P = 0.000). The mean vector surgical effect was 91 % for group A and 70% for group B. Regular astigmatism patterns had a greater benefit from surgery than irregular patterns (P = 0.008). Previous refractive surgery was associated with less-favorable outcome (P = 0.045).

CONCLUSIONS

The current study indicates that the use of CVK provides a benefit compared to keratometry and refraction alone in the planning and outcome of surgical treatment for high postgraft astigmatism.

Report on the COLIPA Workshop on Mechanisms of Eye Irritation

This report summarises the discussions of a workshop sponsored by the European Cosmetics, Toiletries and Perfumery Association (COLIPA). The workshop discussed the state-of-the-art of eye irritancy testing, and made recommendations as to the best ways in which to validate alternatives to the Draize eye irritation test. The importance of understanding the mechanisms of eye irritation, particularly when attempting to improve in vitro prediction of in vivo eye irritancy, was also emphasised.

Purification of an antimicrobial peptide from rabbit aqueous humour

PURPOSE

To identify an antimicrobial factor previously demonstrated in rabbit aqueous humour.

METHODS

Rabbit aqueous humour was fractionated by a multi-stage process involving anion-exchange and size-exclusion liquid chromatography. The antimicrobial effect of aqueous humour fractions upon Staphylococcus aureus were evaluated in an in vitro model. The components of aqueous humour fractions mediating an antimicrobial effect were investigated by SDS-PAGE.

RESULTS

A single peptide of molecular weight approximately 8 kDa was identified which mediated an antimicrobial effect upon Staphylococcus aureus. Attempts to identify the peptide have been unsuccessful.

CONCLUSIONS

Rabbit aqueous humour contains an unidentified peptide that mediates an antimicrobial effect upon Staphylococcus aureus. If such a peptide is present in human aqueous humour it may contribute to the apparent resistance to bacterial infection manifest in the anterior chamber.

A murine model of interlamellar corneal transplantation

AIMS/BACKGROUND

There are more reagents and information available for immunological studies in the mouse compared with other animals. Unfortunately, the mouse penetrating keratoplasty model is associated with high background inflammation which hinders study of the immune response to the graft. To mitigate this drawback, a murine orthotopic corneal interlamellar transplantation model with mild non-specific inflammation was developed.

METHODS

A 1.5 mm diameter full thickness donor corneal button was placed in a 2 mm diameter recipient corneal interlamellar pocket without placement of a suture. The clinical course of graft status was studied daily for 60 days in 30 allografts (donor strain CBA 101 (H-2k) to recipient NIH (H-2q) and 30 syngeneic grafts (NIH to NIH) by slit lamp biomicroscopy and scored for neovascularisation, opacity, oedema, and granularity. In another cohort of animals, histological observation was performed after 30 minutes and on days 10, 20, 30, and 40 after transplantation (four allografts and four syngeneic grafts per time point). Histological study was also performed on grafts without donor epithelium and on interlamellar pockets without grafts.

RESULTS

There was significantly more neovascularisation (NV), opacity, oedema, and granularity in 24/30 allografts (80%) than in syngeneic grafts. Such grafts were defined as rejected. The median time to rejection was 21 days (range 18 to > 60 days). By histology, some allografts showed moderate to heavy cell infiltration which correlated with clinical scores of NV (4-5), opacity (1-3), oedema (1-3), and granularity (1-3). Such infiltration was absent in other allografts and syngeneic grafts.

CONCLUSION

Surgically, corneal interlamellar transplantation could be accomplished in the mouse and rejection could be clearly defined. The model can therefore be useful for in situ study of cell and molecular aspects of corneal graft rejection.

Immunohistochemical detection of cytokines in paraffin-embedded mouse tissues

We have successfully developed a method for the immunohistochemical detection of interleukin 2 (IL-2), IL-4, IL-6, IL-10O, IFNgamma and TNFalpha using monoclonal antibodies (MAb), in sections of mouse tissue embedded in paraffin wax. The method involved fixation in periodate-lysine-paraformaldehyde (PLP), rapid dehydration and infiltration under vacuum with paraffin wax at 54 degrees C. Comparative observations demonstrated that the method gives equivalent or better results than formaldehyde fixed, frozen sections. Since reliable controls, both positive and negative, are paramount for interpretation of immunohistochemical staining, such controls were determined. The following tissues were shown to be suitable as positive controls when using paraffin-embedding: spleen for the detection of TNFalpha, small intestine for IL-2, IL-4 and IL-10, and HSV-1 infected eyes for IL-6 and IFNgamma. We conclude that PLP fixation and low temperature paraffin-embedding is a method which provides both preservation of excellent tissue morphology and reliable immunohistochemical identification of cytokines. These attributes will be invaluable in a wide variety of experimental situations.

Cytokine production in the nervous system of mice during acute and latent infection with herpes simplex virus type 1

Immunocytochemistry on serial paraffin sections was used to monitor the production dynamics of cytokines (IL-2, IL-4, IL-6, IL-10, IFN-gamma and TNF-alpha) and viral antigens in the trigeminal ganglion (TG) and the central side of the dorsal root entry zone (DRE) of mice, following infection of the cornea with herpes simplex virus type 1. In normal TG, scattered satellite cells were TNF-alpha+ and in the DRE, TNF-alpha+ and/or low numbers of IL-6+ cells were detected. On day 3 after infection, foci of TG neurons with viral antigens were surrounded by large numbers of TNF-alpha+ and/or IL-6+ cells and low numbers of IFN-gamma+ cells. IL-2+ and/or IL-4+ cells appeared later, when viral antigens had almost cleared. In the TG, the most striking changes occurred with TNF-alpha, with respect to its source (satellite cells, Schwann cells and infiltrating cells) and the extent and long duration of its production. TNF-alpha was the predominant cytokine throughout acute and latent infection and even by day 30, numbers of satellite cells expressing this cytokine were three times higher than those in normal ganglia. Moreover, in the DRE, TNF-alpha was the only cytokine detected during virus clearance and again, its production continued, along with that of IL-6, on days 20 to 30, in both infiltrating cells and astrocytes. Thus, cytokines, particularly TNF-alpha and perhaps IL-6, from infiltrating cells and resident glial cells may have a role both in virus clearance and in normal homeostatic mechanisms in the nervous system such as repair and protection of neurons from damage.

The Bristol Shared Care Glaucoma Study--validity of measurements and patient satisfaction

BACKGROUND

The aims of the study were to determine (1) whether community optometrists are able to make valid measurements of visual parameters in patients with established or suspect primary open angle glaucoma and (2) patient satisfaction with follow-up by community optometrists.

METHODS

A randomized study was carried out in the former county of Avon in South West England with patients allocated to follow-up by the hospital eye service or by community optometrists. The subjects were 403 patients with established or suspected primary open angle glaucoma attending Bristol Eye Hospital and meeting defined inclusion and exclusion criteria. The main outcome measures were 91) measurements of key visual parameters (intraocular pressure, visual fields and cup/disc ratio) made by hospital eye service and community optometrists, compared with a research clinic reference standard at baseline, and (2) patient satisfaction at baseline and at six months.

RESULTS

Community optometrists were able to make measurements of comparable accuracy to those made in the hospital eye service. Patients were significantly more satisfied with a number of aspects of care provided by community optometrists, particularly those relating to waiting times, compared with those from the hospital eye service.

CONCLUSIONS

Community optometrists are able to make measurements of key visual parameters in patients with established or suspect primary open angle glaucoma which are of comparable quality to the hospital eye service. Follow-up by community optometrists is acceptable to patients. The costs of each option are reported elsewhere.

Efficacy and safety of 0.3% carbomer gel compared to placebo in patients with moderate-to-severe dry eye syndrome

PURPOSE

Carbomer gel is a water-soluble polymeric resin that has been reported to maintain the tear film in contact with the eye for an extended period. The efficacy and safety of this new artificial tear were assessed.

METHODS

A multicenter, single-masked, randomized, placebo-controlled study was carried out on 123 patients with moderate-to-severe dry eyes. The placebo was a mannitol solution with benzalkonium chloride 0.008% as preservative. Patients were observed over an 8-week period, and subjective and objective changes analyzed, compared to a baseline of no therapy, after 1 to 7 days washout period from previous medication.

RESULTS

All primary subjective symptoms decreased significantly in the carbomer gel-treated group compared to the placebo group (i.e., dryness, discomfort, and foreign body sensation). The carbomer gel also significantly improved the rose bengal staining score relative to placebo. When data for the primary subjective efficacy variables were stratified for disease severity, there was a statistically significant improvement from baseline by day 10 for severely affected patients and from day 42 for patients with moderate disease. Secondary subjective symptoms that improved significantly in the tear gel group compared to placebo were photophobia, erythema, tear breakup time, blurry-filmy, dry-sandy sensation, and physician impression. However, no significant improvements in the secondary subjective symptoms of tearing, itching, scaling, conjuctival discharge, palpebral conjunctival redness, bulbar conjuctival redness, conjunctival luster, relief of discomfort, ease of use, and overall acceptability were found in either group over the baseline score. In addition, neither carbomer gel nor placebo improved the baseline fluorescein staining score or the Schirmer test score. Two patients suffered local allergic reactions to the carbomer gel or its preservative, which settled on withdrawal of the medication.

CONCLUSIONS

Carbomer gel was more efficacious than was placebo in improving a number of subjective and objective symptoms of moderate-to-severe dry eye syndrome. The results of this study indicate that carbomer gel was a safe as was the placebo.

Conclusions of the corneal transplant follow up study. Collaborating Surgeons

AIM

On the basis of finalised data from the Corneal Transplant Follow up Study to identify and quantify factors influencing corneal graft outcome in terms of graft survival, rejection, visual acuity, and astigmatism.

METHODS

Multifactorial analysis of 2777 grafts registered by the UK Transplant Support Service from July 1987 to June 1991.

RESULTS

Several recipient factors influencing graft survival, rejection, and visual acuity were identified, but no donor factors. Of the operative factors amenable to change, mixed suturing was associated with reduced graft survival, and larger grafts with increased risk of rejection but better visual acuity when surviving. There was increased risk of rejection with poor matching at HLA class I antigens, but mismatched HLA-DR grafts suffered less rejection than those with zero HLA-DR mismatches. Recipient age below 10 years was associated with increased risk of both rejection and graft failure. However, whereas increasing age above 10 years was not associated with differential graft survival, it was significantly associated with decreasing risk of rejection.

CONCLUSIONS

While confirming possible benefits of HLA-A and B matching, the expense and delay involved in awaiting matched HLA-DR tissue is unlikely to be justified. Other donor factors are unrelated to graft outcome following screening of tissue by eye banks. The highest rates of graft failure and rejection happen in the early postoperative period, and factors influencing visual outcome are also apparent at this stage.

Ganciclovir ophthalmic gel (Virgan; 0.15%) in the treatment of herpes simplex keratitis

PURPOSE

Ganciclovir is a broad-spectrum virustatic agent. Its efficacy and safety after ocular application have been demonstrated in studies of herpetic keratitis in rabbits. Two strengths of ganciclovir gel (0.05 and 0.15%) were compared with 3% acyclovir ointment in the treatment of superficial herpes simplex keratitis in humans.

METHODS

Two multicenter randomized clinical trials were carried out in Africa (Trial 1) and Europe (Trial 2). Sixty-seven patients (Trial 1) and 37 patients (Trial 2) from herpetic ulceration were recruited.

RESULTS

The results showed no statistically significant difference between the treatment groups, although the healing rates tended to be better in the group receiving 0.15% ganciclovir gel, with healing rates of 85% (Trial 1) and 83% (Trial 2) as compared with 72% (Trial 1) and 71% (Trial 2) in the group receiving acyclovir ointment. Local tolerance was found to be superior with the gel formulation of ganciclovir with fewer complaints of discomfort (stinging, burning) or blurred vision after application of the drug. Systemic absorption of the drug was low. No hematologic changes were detected.

CONCLUSIONS

These findings support the efficacy of ganciclovir gel in the treatment of ulcerative herpes simplex keratitis and demonstrate its superior local tolerance when compared with acyclovir ointment.

Histopathology and molecular cytogenetics of a corneal opacity associated with the trisomy 8 mosaic syndrome (46,XY/47,XY, +8)

The trisomy 8 mosaic syndrome (Tr8MS), karyotype 46,XY/47,XY, +8, is a rare multisystem disorder that may be associated with corneal opacity. We report the case of a dysmorphic infant with multiple congenital abnormalities referred to our unit with a congenital corneal opacity. Subsequent chromosomal analysis of peripheral leucocytes demonstrated constitutional Tr8MS. At 4 years of age, lamellar keratoplasty was performed. Histological examination confirmed the lesion to be consistent with a corneal choristoma. Cytogenetic studies using in situ hybridisation techniques showed the presence of trisomic cells in cell culture derived from the tissue in higher proportion (92%) than in the blood (44%). Amplification of the c-myc oncogene on chromosome-8 could not be detected in cells cultured from the corneal lesion. Although not proof, these findings lend support to the concept of the corneal lesion representing a focus of viable trisomic cells rather than an inflammatory response to a nidus of effete cells.

Factors influencing the suitability of organ-cultured corneas for transplantation

PURPOSE

To assess the influence of donor and storage factors on the suitability of organ-cultured corneas for penetrating keratoplasty (PKP) using multifactorial regression analysis.

METHODS

Corneas (mean donor age, 57 years; standard deviation, 21 years) were stored by organ culture at 34 degrees C for up to 5 weeks (mean, 22 days; standard deviation, 6 days). The endothelium was assessed by light microscopy, and corneas with < 2200 cells/mm2 were considered unsuitable for PKP.

RESULTS

Of the 9250 corneas stored between 1992 and 1994, 59% were issued for PKP, 5% were discarded because of bacterial or fungal contamination, and 30% were unsuitable for PKP owing to endothelial deficiencies. Donor age had the strongest influence on suitability for PKP: > 80% of corneas from donors younger than 40 years of age were issued for PKP compared with only 45% of corneas from donors 80 years of age and older. There was an overall decline in the percentage of corneas suitable for PKP with increasing storage time, but the rate of this decline was inversely related to donor age. Cause of death and post mortem times to enucleation and to storage had only a small influence on suitability for PKP.

CONCLUSIONS

Criteria based on endothelial assessment rather than on donor age allow corneas from donors of all ages, stored by organ culture for extended periods, to be used for PKP. Organ culture also allows corneas with bacterial or fungal contamination to be identified and discarded before they are grafted.

Epithelial downgrowth following penetrating keratoplasty with a running adjustable suture

A 78-year-old female patient who had a third penetrating keratoplasty for aphakic bullous keratopathy and iris fixation of a posterior chamber intraocular lens using a single, 10-0 nylon running suture technique developed a suture track leak postoperatively. Attempts to ease the tension on the suture track reduced the astigmatism and stopped the leak temporarily. Eighteen months after the procedure, epithelial downgrowth was noted on the corneal graft on both sides of the leak site and intraocular pressure was elevated. A fourth penetrating keratoplasty combined with a trabeculectomy was performed. To our knowledge, this is the first report of epithelial downgrowth associated with suture adjustment following the single, continuous suture technique.

Reactivation of herpes simplex virus type 1 in the mouse trigeminal ganglion: an in vivo study of virus antigen and immune cell infiltration

The corneas of latently infected mice were UV irradiated to induce reactivation of herpes simplex virus type 1 (HSV-1) in the trigeminal ganglion (TG). On days 1 to 4 after irradiation, TG were removed, serially sectioned and double stained to identify immune cells and virus antigens. Virus antigen was detected in small numbers (most commonly one) of neurons per ganglion as early as day 1, confirming the rapidity of reactivation and the neuron as the likely site of this event. The immune response was also rapid and effective since virus antigen was identified in immune cells at day 1 and by day 4 all samples were negative. The predominant infiltrating cells on days 1 and 2, when virus antigen was present and being cleared, were T cells, both CD4+ and CD8+. Later, large numbers of B cells appeared, suggesting that local antibody production may also be involved in controlling the reactivated infection. The observations suggest that a significant proportion of reactivation events do not result in disease of the eye or shedding of virus in the tear film. However, they also suggest that as little as one reactivating neuron in the ganglion may be sufficient to lead to such disease and/or shedding.

Corneal organ culture: effects of serum and a stabilised form of L-glutamine

AIMS

Organ culture medium for corneas contains labile components, such as L-glutamine, whose loss could be a limiting factor to the length of storage. The medium is also supplemented with fetal bovine serum (FBS), which can vary significantly between different batches. The aim of this study was to establish the need for FBS during corneal organ culture, and to determine whether substitution of L-glutamine by the stable dipeptide L-analyl-L-glutamine was beneficial.

METHODS

Porcine corneoscleral discs were suspended in 80 ml of organ culture medium (HEPES buffered Eagle's MEM with Earle's salts, 26 mmol/l NaHCO3, penicillin, streptomycin, and amphotericin B) and kept at 34 degrees C. The medium contained either 2 mmol/l L-glutamine or 2 mmol/l L-analyl-L-glutamine, and was either serum free or contained 2% FBS. At weekly intervals, five corneas from each group were stained with trypan blue and alizarin red S, and the surface area and shape of 100 endothelial cells were determined for each cornea.

RESULTS

No differences were observed between corneas in organ culture medium with L-glutamine or L-analyl-L-glutamine. In serum free medium, endothelial cell density remained constant for the first week, but then declined rapidly over the next 2 weeks. With 2% FBS, there was no loss of endothelial cells for the first 2 weeks, but cell density had halved by the fourth week of organ culture.

CONCLUSION

The presence of 2% FBS extended the period of endothelial stability, but no advantage was gained from the stabilised form of L-glutamine. The overall loss of endothelial cells was much greater than would be expected for human corneas.

Immune cell infiltration in corneas of mice with recurrent herpes simplex virus disease

Reactivation of latent herpes simplex virus type 1 (HSV-1) infection was induced by UV irradiation of the corneas of latently infected mice. On days 1-4 after stimulation, infectious virus was sought in nervous and ocular tissue. On days 4, 7 and 10, eyes with either recurrent epithelial or stromal disease and appropriate controls were stained to identify immune cells and HSV-1 antigens. The maximum incidence of infectious virus was on day 2 when 5/10 ophthalmic parts of the trigeminal ganglion yielded HSV. Thus in this mouse model, as in humans, reactivation of virus in the trigeminal ganglion is the likely source of virus producing recurrent disease and shedding in the tear film. On day 4, when virus antigens were still present, granulocytes were the predominant infiltrating cell in corneas with either type of disease. Small numbers of T cells, dendritic cells and cells expressing MHC class II were also present. In stromal disease, the granulocyte infiltrate persisted and T cells remained sparse. In contrast, in epithelial disease, granulocyte numbers rapidly declined and both CD4+ and CD8+ T cells (present at a ratio of 1:1) increased significantly. The secondary immune response to virus antigen is more rapid and vigorous than that during primary corneal infection. Granulocytes may play a role in the initial clearance of virus, however, the other types of cells present early on provide the potential for a local secondary immune response. The high proportion of CD8+ cells in epithelial disease compared with stromal disease suggests that they may be acting as suppressors.

Viability of keratocytes in epikeratophakia lenticules

AIM

To study the influence of cryoprotectant, cooling rate, and warming rate on recovery and viability of keratocytes from corneas for cryolathing.

METHODS

Corneas were frozen at -50 degrees C for 2 minutes either after exposure to 10% dimethyl sulphoxide in Eagle's MEM for 15 minutes at room temperature (about 22 degrees C), or without earlier exposure to the cryoprotectant. Corneas were cooled either rapidly (20 degrees C/min) or slowly (1 degree C/min), and they were warmed either rapidly (> 50 degrees C/min) by direct transfer into medium at 22 degrees C or slowly (< 20 degrees C/min) in air at 22 degrees C. The cryoprotectant was removed by dilution in medium containing 0.5 mol/l sucrose. Recovery of keratocytes was determined by using collagenase digestion to release the cells from the stroma and trypan blue staining. Viability was assessed by the outgrowth of cells from stromal explants in primary tissue culture.

RESULTS

The use of a cryoprotectant before freezing was beneficial, irrespective of the different cooling and warming regimens. Both collagenase digestion and tissue culture revealed that keratocyte survival was improved when corneas were warmed rapidly rather than slowly. The collagenase digestion assay showed an apparently higher recovery of keratocytes after slow cooling (54.3%) than after rapid cooling (34.1%), but no differences in cell viability could be demonstrated by primary tissue culture.

CONCLUSION

Although in these experiments slow cooling apparently provided the best recovery of keratocyte numbers (though not viability), previous work had revealed some disruption of the epithelial basement membrane after slow cooling. If viable keratocytes and good preservation of epithelial basement membrane are considered to be prerequisites for epikeratophakia lenticules then it is suggested that corneas should be prepared for cryolathing by freezing rapidly after exposure to 10% dimethyl sulphoxide and, following cryolathing, they should be warmed rapidly.

Recurrent herpes simplex after corneal transplantation in rats

PURPOSE

To ascertain the effect of trauma from surgery and rejection on the incidence and timing of recurrent herpes simplex virus (HSV) disease after corneal transplantation. To locate virus antigen and identify cells of the immune system infiltrating corneas with recurrent disease.

METHODS

PVG rats were inoculated on the cornea with HSV-1 McKrae. Recurrent disease was induced either by ultraviolet (UV)-irradiation of the cornea or by corneal transplantation. After corneal transplantation, animals shedding virus in the tear film were killed on days 1 to 4 of shedding. Eyes were fixed, embedded, sectioned, and stained for virus antigens, infiltrating cells, major histocompatibility complex class II, and adhesion molecule molecule expression.

RESULTS

In the first 15 days after corneal transplantation, 8 of 91 rats shed virus, and between days 16 and 30, an additional 3 of 60 rats shed virus (12% of total rats, comparable to the percent that shed after UV irradiation). Shedding sometimes was accompanied by punctate epithelial lesions in the recipient cornea and stromal opacity. The rejection process itself did not induce or exacerbate recurrent disease. In all corneas examined from eyes that shed virus, antigen was found in several locations at the graft-host junction, sometimes in the absence of clinical signs of disease, and frequently it extended through the stroma to the endothelium. Granulocytes were the main infiltrating cell in areas of virus antigen.

CONCLUSIONS

Corneal transplantation trauma is a stimulus to recurrent disease of similar potency to UV irradiation. The graft-host junction is an area in which virus spreads easily and can reach the endothelium readily. In humans, the incidence of recurrent disease at this location may be greater than has been recognized.

Randomised trial of ganciclovir and acyclovir in the treatment of herpes simplex dendritic keratitis: a multicentre study

AIMS

This study was designed to assess the relative efficacy of topical ganciclovir 0.15% gel and acyclovir 3% ointment in the treatment of herpes simplex dendritic keratitis.

METHODS

Both treatment modalities were administered on a five times daily basis to patients suffering from herpes simplex keratitis. Patients were assigned randomly to one of the two treatment groups for the purpose of the trial. They were then examined on days 2, 7, 10, and 14 to assess the rate of healing of the dendritic ulceration.

RESULTS

There was no statistically significant difference detected in the rate of healing between the two treatment groups over the course of the trial.

CONCLUSIONS

Review of the relative efficacy of topical ganciclovir and acyclovir in the treatment of herpes simplex dendritic keratitis showed that both treatment modalities were equally effective in their ability to heal the viral induced corneal ulceration. There were no significant side effects or adverse effects reported for either treatment modality.

Cyanoacrylate glue treatment for persistent aqueous leak following postkeratoplasty relaxing incisions with compression sutures

In spite of improvements in surgical techniques, donor materials and postoperative care, high astigmatism remains a quite common problem following penetrating keratoplasty [1]. Whenever the residual astigmatism cannot be corrected with spectacles or contact lenses, surgical treatment is required. Relaxing incisions combined with compression sutures is one of the most common methods used for this purpose [2, 3]. We report herein a case of persistent aqueous leak following relaxing incisions for the correction of postkeratoplasty astigmatism. The leak failed to respond to a bandage contact lens and resuturing and was eventually successfully treated with the use of cyanoacrylate glue. A marked regression of the surgical effect was observed in this case.

Clinical and surgical factors influencing corneal graft survival, visual acuity, and astigmatism. Corneal Transplant Follow-up Study Collaborators

PURPOSE

To quantify clinical and operative factors that influence corneal graft outcome.

METHODS

A multifactorial analysis was done on 2242 corneal grafts registered by the United Kingdom Transplant Service from July 1987 to June 1991.

RESULTS

There was an increased risk of graft failure in patients with preoperative diffuse and other noncentral stromal edema, less-common eye diseases, small trephine size, difference in donor and recipient sizes greater than 0.25 mm, and use of mixed continuous and interrupted sutures. Visual acuity 3 months after surgery was poorer in patients who had glaucoma and low visual acuity preoperatively, small trephine size, and combined vitreous surgery. Use of interrupted sutures resulted in higher astigmatism at 3 months.

CONCLUSIONS

After allowing for the effects of recipient factors, surgical factors significantly affected corneal graft outcome. No factors that showed significant benefits for graft survival also adversely affected visual performance. Details of medical history, clinical condition, and surgical method failed to predict more than a small proportion of observed variability in visual performance of functioning grafts.

Acanthamoeba keratitis: risk factors and outcome

AIMS/BACKGROUND

This study was initiated to investigate risk factors for and outcome of Acanthamoeba keratitis.

METHODS

Results of treatment were studied in 22 patients (23 eyes) presenting to Bristol Eye Hospital between 1985 and February 1995. Details related to the use and disinfection of contact lenses were also obtained. An additional two patients who were seen at Bristol but mainly treated elsewhere were surveyed for contact lens related information only.

RESULTS

The incidence of Acanthamoeba keratitis rose substantially in the 1990s: three patients presented before 1990, while the remaining 21 presented between January 1990 and February 1995. Eleven patients have presented since january 1994. All of the patients in this series were contact lens wearers, 16 (67%) using daily wear disposable contact lenses. Contact lens disinfection data were available in 22 patients of whom 11 (50%) were using chlorine disinfectant. Other types of disinfection were much less common. Four patients (18%) had not used any disinfectant. During the course of the series the average diagnostic delay has fallen markedly, although in 77% of patients a diagnosis of a viral keratitis, most commonly herpes simplex, was made on first presentation. All but three of the series were treated with a combination of polyhexamethylene biguanide and propamidine isethionate. Penetrating keratoplasty was performed in 9/23 eyes (39%); in all of these eyes diagnosis was delayed for at least 6 weeks. All but one of the eyes in the series achieved a visual acuity of 6/9 or better after treatment, and 18 eyes (78%) saw 6/6 or better.

CONCLUSIONS

Most patients with Acanthamoeba keratitis can now expect a good visual result and cure by medical therapy alone is favoured by early diagnosis.