Local suppression of IL-1 by receptor antagonist in the rat model of corneal alkali injury

Proinflammatory cytokines, including interleukin-1 (IL-1) have been implicated in the inflammation that follows corneal alkali injury. The purpose of this series of experiments was to test whether topically applied interleukin-1 receptor antagonist (IL-1ra) could suppress corneal inflammation and promote transparency after alkali injury. Alkali injury was induced on day 0 by application of 1N NaOH to both eyes of Wistar rats (n = 28). Immediately thereafter, eyes received either topical IL-1ra (20 mg ml(-1)) in 0.2% sodium hyaluronate or vehicle alone three times daily during days 0-14. Biomicroscopic features including corneal opacity and neovascularization were assessed using a standard grading scheme. Inflammation was quantified histologically. Corneas excised at day 3 and 7 (randomly selected six eyes in each group per time point studied) were homogenized, and levels of IL-1alpha, IL-1beta, IL-6, IL-8, IL-10, and RANTES were quantified by enzyme-linked immunosorbent assay. Epithelial wound healing was examined by computed analysis of fluorescein stained corneal photographs taken daily until day 14. According to these evaluations, eyes treated with IL-1ra maintained corneal transparency with minimal neovascular invasion. Additionally, corneal damage and cell infiltration were reduced on day 7 (infiltration cells were almost 40% decreased). All cytokine/chemokine levels in IL-1ra treated eyes were significantly lower at day 3, and IL-6 and IL-10 remained significantly lower at day 7 compared to vehicle-treated eyes. IL-1ra treatment retarded epithelial wound healing in the early stage (day 1-4); however, subsequently IL-1ra treated eyes had enhanced healing with full epithelial closure at nearly the same time point as vehicle-treated eyes (day 10). We conclude that local antagonism of IL-1 after alkali injury can significantly decrease corneal inflammation and lead to enhanced corneal transparency.

Why daily wear is still better than extended wear

Among the many problems complicating contact lens wear, microbial keratitis is of most concern because of its potential for substantial morbidity. Three decades of basic and clinical research suggest that risk factors include poor care compliance and extended wear through one or multiple sleep cycles. Many believe the latter problem is caused in part or in whole to contact lens-induced hypoxia. New contact lenses, both rigid and soft, have been developed that allow oxygen delivery equivalent to the noncontact lens state, under open-eye conditions and close to the same even for closed-eye conditions. But will such lenses reduce the risk for microbial keratitis? The authors argue that until such a conclusion is reached through clinical trials, the question remains in doubt.

Endoscopic transnasal orbital decompression for thyrotoxic orbitopathy

OBJECTIVE

To evaluate the efficacy of endoscopic transnasal orbital decompression alone for thyrotoxic orbitopathy.

DESIGN

Retrospective review of consecutive procedures.

SETTING

Tertiary referral otorhinolaryngology centre.

PATIENTS

Twenty-three eyes of 14 patients.

INTERVENTION

Endoscopic transnasal orbital decompression.

MAIN OUTCOME MEASURES

Proptosis reduction, intra-ocular pressure reduction, exposure keratitis reduction, visual acuity improvement, and complication rate.

RESULTS

There were no surgical complications for the 23 orbital decompressions. Proptosis reduction was achieved in 22 (96%) eyes. The mean proptosis reduction was 4.6 mm (median, 5.0 mm; range, 1.0-8.0 mm). The postoperative intra-ocular pressure decreased after surgical decompression in 20 (87%) eyes with a mean reduction of 11 mm Hg (median, 6 mm Hg; range, 1-35 mm Hg). Of the 15 eyes with incomplete closure of the eyelid before the operation, 11 (73%) had complete eyelid closure after surgical decompression. Of the other four eyes that had incomplete closure, the gaps were reduced. The visual acuity was improved for 16 (70%) eyes with a median improvement of 3 Snellen lines (range, 1-8 lines).

CONCLUSION

Endoscopic transnasal medio-inferior orbital wall decompression is a safe and adequate treatment for thyrotoxic orbitopathy with proptosis, exposure keratitis, and visual loss.

Polyclonal human antibodies reduce bacterial attachment to soft contact lens and corneal cell surfaces

Bacterial keratitis due to Pseudomonas aeruginosa is a potentially serious complication of extended-wear contact lens use. Adhesion of P. aeruginosa to soft contact lens materials or corneal endothelial cells in the presence of pooled human immunoglobulins and/or neutrophils in artificial tear fluid was studied in vitro as a potential method to treat contact lens-associated infection. Soft hydrophilic contact lens materials equilibrated in sterile saline were soaked in artificial tear fluid for 18 h prior to use. P. aeruginosa IFO 3455 was added to groups of lenses or confluent cultured bovine corneal endothelial cells with varying amounts of human polyclonal immunoglobulin (IgG) and human blood neutrophils or serum albumin as a control. After 2 or 4 h incubation, adherent viable bacteria on lenses were quantified. Fluorescence microscopy was used to assess bacterial adherence to bovine corneal endothelial cells in the presence and absence of IgG and neutrophils. Various concentrations of albumin had no effect on adhesion. Human immunoglobulin solutions (25 mg/ml) reduced P. aeruginosa adhesion by nearly 1 log and 2 logs after 2 and 4 h incubations, respectively. Neutrophils in combination with 25 mg/ml IgG reduced bacterial adhesion approximately 1 log over reduction in adhesion by neutrophils alone. Diluted human IgG (10 mg/ml) did not significantly decrease bacterial adhesion after 2 or 4 h, but did reduce adhesion in combination with human neutrophils at both time points. Similar reductions in amounts of fluorescently labeled bacteria adhered to cultured monolayers of corneal endothelial cells under these conditions were qualitatively observed.

[Diffuse lamellar keratitis: prophylactic treatment with ketorolac tromethamine 0.5% in an animal model]

PURPOSE

The objective of this study is to evaluate the use of a topical non-steroidal anti-inflammatory drug in the treatment of induced diffuse lamellar keratitis (DLK) in an animal model.

MATERIALS AND METHODS

A corneal flap was created in 40 eyes of 20 Dutch-belted rabbits using the ASC microkeratome. The interface was inoculated with either Pseudomonas Aeruginosa Lipopolysaccharide (LPS) endotoxin or Ultra Palmolive liquid dish washer. The rabbits were divided in two groups: Group I (n=20) treated with ketorolac tromethamine ophthalmic solution 0.5% 4 times a day and the group II (n=20) used as control. The rabbits were examined at the slit lamp at day 1, 3, 5 and 7 postoperatively. DLK was graded from I-IV.

RESULTS

At the end of the study 31 eyes were available for evaluation. 28 eyes (90%) developed DLK: 86% of the treated group and 94% of the control group during the follow-up. The treated group showed a lower rate of DLK as well as a lower severity. However, no statistically significant difference was found when comparing both groups (P>0.05).

CONCLUSION

Pseudomonas aeruginosa LPS endotoxin and Palmolive Ultra can induce DLK in rabbit eyes. The postoperative prophylactic treatment with a topical non-steroidal anti-inflammatory drug showed a tendency towards a lower DLK rate as well as the severity of the disease.

[Diffuse lamellar keratitis. Postoperative prophylactic treatment with corticosteroids in an experimental animal study]

PURPOSE

The aim of this experimental ani-mal study was to induce diffuse lamellar keratitis (DLK), and investigate a prophylactic treatment with corticosteroids.

MATERIALS AND METHODS

A corneal flap was cut in 40 eyes from 20 Dutch-belted rabbits and the interface inoculated with either Pseudomonas aeruginosa lipopolysaccharide (LPS) endotoxin ( n=21) or Palmolive Ultra soap ( n=19). Half of the eyes were treated with topical corticosteroids and the other half remained untreated. Slitlamp examinations were performed 1, 3, 5 and 7 days postoperatively and DLK was graded from I-IV.

RESULTS

At the end of the study 33 eyes were available for evaluation and 94% of the non-treated eyes developed DLK. Out of those eyes treated with steroids 19% developed DLK during the 1 week follow-up period. This was statistically significantly lower ( P=0.018) when compared to the untreated group.

CONCLUSION

Pseudomonas aeruginosa LPS endotoxin as well as Palmolive((R)) Ultra caused a very high rate of DLK in rabbit eyes. The postoperative prophylactic treatment with corticosteroids showed a statistically significant lower DLK rate in this rabbit eye model.

Is there a question of safety with continuous wear?

The availability of silicone-containing hydrogel contact lenses (SCHCLs) has refocused attention on the risks associated with continuous wear (CW). The major barrier to optometrists prescribing CW in Western societies is a perceived danger of microbial keratitis (MK). This perception has been shaped largely by educators who have developed their opinions from case reports in the ophthalmic literature, sensationalist lay press reports and later epidemiological studies and from prominent physicians in tertiary referral centres, following an increased incidence of MK with extended wear (EW) of traditional hydrogel materials. The basis for the perceived lack of safety is the higher risk of MK with EW compared to daily wear and incidence figures that suggest an unacceptable level of MK in a population at risk, albeit a small risk on an individual basis. In this paper, I re-evaluate the validity of the previous data and challenge the conclusions regarding the nature of the risk with traditional hydrogel lens materials. Areas under scrutiny include diagnostic criteria, morbidity caused by different micro-organisms, potential bias in studies and reports, analysis of visual outcomes and cost to the community, and improvements over time in the understanding and handling of contact lens-related complications. Significant loss of vision with EW appears to be less frequent than is the common perception. When the risks are placed in the perspective of other data such as that for refractive surgery, the arguments against EW do not seem so compelling. The high oxygen transmissibility of SCHCLs may enable safe CW but a large-scale epidemiological study is needed to allay remaining doubts. Any such future studies should note the points outlined in this document.

Intraocular dexamethasone delivery system for corneal transplantation in an animal model

PURPOSE

To assess the efficacy of a new intraocular biodegradable polymer dexamethasone drug delivery system (DEX DDS) in a high-risk corneal transplantation model.

METHODS

Lewis rats that received orthotopic corneal transplants (Balb/c mice donors) were divided into three groups (six rats in each); group 1 received no treatment and served as controls, group 2 was treated with 0.1% betamethasone eyedrops three times daily for 6 weeks, and group 3 received DEX DDS in the anterior chamber at the time of transplantation.

RESULTS

All grafts in the untreated control group were rejected within 8 days. In the betamethasone eyedrop group, five eyes (83%) were rejected during the 8-week study period. None of the grafts in the DEX DDS group was rejected. The administration of DEX DDS significantly prolonged the survival rate of the corneal grafts (p < 0.001, log-rank test).

CONCLUSION

DEX DDS is effective in suppressing graft rejection in high-risk corneal transplantation.

Role of instrument cleaning and maintenance in the development of diffuse lamellar keratitis

OBJECTIVE

To determine if instrument cleaning techniques affect the rate of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

DESIGN

Retrospective case series.

PARTICIPANTS

Two hundred ten eyes of 109 patients.

METHODS

A record review was performed of all patients who underwent LASIK at the Jules Stein Eye Institute from April 1 through June 24, 1999. During the first 6 weeks, the instruments used in LASIK surgery were cleaned according to our conventional protocol. At the end of this 6-week period, the cleaning protocol was modified and used for a subsequent 6-week period. For each eye during the two periods, the status of DLK on the first postoperative day was recorded.

MAIN OUTCOME MEASURES

Presence of DLK.

RESULTS

During the first 6-week period, 118 eyes of 60 patients underwent LASIK surgery. In the subsequent 6 weeks, 92 eyes of 49 patients underwent LASIK surgery. The two groups included patients with similar demographic background: gender, age, and target correction. Diffuse lamellar keratitis was present in 13 of 118 eyes (11%) using our conventional protocol. In only 2 of 92 eyes (2%) did DLK develop after the protocol was modified. Using the chi-square test, the difference between the two groups was statistically significant (P = 0.01).

CONCLUSIONS

Diffuse lamellar keratitis is a fairly uncommon phenomenon after LASIK surgery. Although the cause remains to be elucidated, these results demonstrated a reduced incidence of DLK associated with alteration of cleaning procedures and a decrease in stagnant instrument cleaning fluids. The authors recommend that refractive centers avoid the use of stagnant fluids in their instrument cleaning and sterilizing protocols to minimize the occurrence of DLK outbreaks.

A comparison of the use of an ATP-based bioluminescent assay and image analysis for the assessment of bacterial adhesion to standard HEMA and biomimetic soft contact lenses

The aim of this study was to investigate in vitro adhesion of clinically relevant bacteria to standard HEMA and novel biomimetic soft contact lenses (SCL) using bioluminescent ATP assay and image analysis. Unworn SCL were incubated with Pseudomonas aeruginosa, Staphylococcus epidermidis or Serratia marcescens suspended in sterile phosphate buffered saline (PBS). The level of bacterial adhesion after 1, 2, 4, 6 and 18h, was assessed using both image analysis and a bioluminescent ATP assay. Species differences in the overall level of adhesion to the different types of lens were observed using both measurement techniques. Generally bacterial adhesion was shown to peak at 4-6 h, then decline to a much lower level by 18 h. After 4 h, adhesion of all species of bacteria to the biomimetic SCL (omafilcon A) was found to be significantly lower than to the standard HEMA SCL (polymacon) (p<0.05. Student's t-test, n = 4). Both these techniques demonstrated that novel biomimetic SCL materials exhibit significantly lower bacterial adhesion in vitro compared to standard HEMA SCL materials. SCL manufactured with these novel biomimetic materials may reduce the risk of infection.

Effector mechanisms of protection against Pseudomonas aeruginosa keratitis in immunized rats

Pseudomonas aeruginosa is an opportunistic pathogen which causes sight-threatening corneal infections in humans. The purpose of this study was to evaluate various immunization routes that may provide protection against Pseudomonas keratitis and to define the molecular mechanisms involved in the protection. Sprague-Dawley rats (10 to 12 weeks old) were immunized using paraformaldehyde-killed P. aeruginosa (strain 6206) via oral, nasal, and intra-Peyer's patch (IPP) routes followed by an ocular topical booster dose. Scratched corneas were challenged with an infective dose of P. aeruginosa. Following clinical examination, eyes were enucleated for histology, polymorphonuclear leukocyte (PMN) quantitation, bacterial count, enzyme-linked immunosorbent assay, and RNase protection assay. PMN infiltration was higher early (4 h) during the infection in immunized rats than in nonimmunized rats. Later during the infection, the number of PMNs diminished in immunized rats while in nonimmunized animals the number of PMNs continued to increase. Bacteria were cleared much faster from immunized groups than from the nonimmunized group, and the nasally immunized group had the most efficacious response among the immunized groups. Nasal and IPP immunization groups had increased cytokine expression of interleukin-2 (IL-2) and IL-5 and differed from each other for IL-6. All three immunized groups had significantly reduced IL-1 beta levels when compared with the nonimmunized rats and a significantly altered profile for CINC-1 expression. This study has shown that the route of immunization modulates the inflammatory response to ocular P. aeruginosa infection, thus affecting the severity of keratitis and adverse pathology, with nasal immunization being the most effective.

Postoperative Inflammation, Microbial Complications, and Wound Healing Following Laser in situ Keratomileusis

Although the biology of corneal wound healing is only partly understood, healing after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) differs in many respects, and the mechanisms appear to be differently controlled. There is less of an inflammatory and healing response after LASIK, but a longer period of sensory denervation. The cellular, molecular, and neural regulatory phenomena associated with postoperative inflammation and wound healing are likely to be involved in the adverse effects after LASIK, such as flap melt, epithelial ingrowth, and regression. Interface opacities in the early postoperative period include diffuse lamellar keratitis (DLK), microbial keratitis, epithelial cells, and interface opacities. Diffuse lamellar keratitis (sands of the Sahara syndrome) describes an apparently noninfectious diffuse interface inflammation after lamellar corneal surgery probably caused by an allergic or a toxic inflammatory reaction. Noninfectious keratitis must be distinguished from microbial keratitis to avoid aggressive management and treatment with antimicrobial drugs. Microbial keratitis is a serious complication after LASIK, but a good visual outcome can be achieved following prompt and appropriate treatment.

Comparison of the efficacy and safety of valaciclovir and acyclovir for the treatment of herpes zoster ophthalmicus

OBJECTIVE

To compare the efficacy and safety of valaciclovir and acyclovir in immunocompetent patients with herpes zoster ophthalmicus.

DESIGN

A multicenter, randomized, double-masked study.

PARTICIPANTS

One hundred ten immunocompetent patients with herpes zoster ophthalmicus diagnosed within 72 hours of skin eruption were treated; 56 were allocated to the valaciclovir group and 54 to the acyclovir group.

METHODS

Patients randomized to the valaciclovir group received two 500-mg tablets of valaciclovir three times daily and one tablet of placebo twice daily. Patients in the acyclovir group received one 800-mg tablet of acyclovir five times daily and one tablet of placebo three times daily for 7 days.

MAIN OUTCOME MEASURES

Main outcome measures included the frequency, severity, and duration of ocular complications, patient reports of zoster-associated pain, and the outcome of skin lesions. Tolerance was also assessed on the incidence and types of adverse effects and changes in laboratory parameters. The analysis was mainly descriptive and performed on an intent-to-treat basis.

RESULTS

Ocular complications of herpes zoster ophthalmicus were similar in the valaciclovir and acyclovir treatment groups. The main complications were conjunctivitis (54% and 52%, respectively), superficial keratitis (39% and 48%, respectively for punctate keratitis; 11% in each group for dendritic keratitis), stromal keratitis (13% in each group), and uveitis (13% and 17%, respectively). The long-term outcomes of these ocular complications were favorable and similar in both treatment groups. Pain duration and severity and outcome of skin lesions were similar between groups. Most patients reported prodromal pain. After 1 month, 25% of patients in the valaciclovir group and 31% in the acyclovir group still reported pain. The percentage of patients experiencing postherpetic neuralgia decreased during follow-up. The tolerance to acyclovir and valaciclovir was comparable and considered good. The most frequent adverse events were vomiting and edema of the eyelids or face (3%-5%). Three serious adverse events not linked to the study drugs occurred.

CONCLUSIONS

Valaciclovir is as effective as acyclovir in preventing ocular complications of herpes zoster ophthalmicus, including conjunctivitis, superficial and stromal keratitis, and pain. Tolerability of the two drugs is similar, but the dosing schedule of valaciclovir is simpler.

Diffuse lamellar keratitis related to endotoxins released from sterilizer reservoir biofilms

OBJECTIVE

To investigate the risk factors and control mechanisms used to control the outbreak of diffuse lamellar keratitis (DLK) associated with laser in situ keratomileusis (LASIK) and examine the relationship between DLK and endotoxins released from sterilizer biofilm reservoirs.

DESIGN

Clinic-based cohort and laboratory study.

PARTICIPANTS

All patients undergoing LASIK at our clinic from October 7, 1998 through August 31, 1999. The case definition was a diffuse infiltrate in the interface developing within the first week after surgery.

INTERVENTIONS

Biofilm control in the sterilizer, changes in sterilizer, distilled water, instruments, and irrigating fluids.

MAIN OUTCOME MEASURES

The incidence of DLK after LASIK surgery.

RESULTS

There were 983 evaluable patients, with three whose DLK status was not recorded. There were 52 cases of DLK. Burkholderia pickettii was isolated from the sterilizer reservoir. Potential risk factors and associations, for which there was no significant difference, included age and sex of the patients, surgeon, operating suite temperature or humidity, drapes used, saline solutions used, time of day the surgery was performed, and microkeratome use. Sterilizers 1 and 2, before biofilm control, were compared with sterilizer 3, after control. The relative risk was 9.4 (confidence limits [CL], 7.5-11.8) for sterilizer 1 versus 3 and 18. 7 (CL, 11-32) for sterilizer 2 versus 3. Three cases occurred after biofilm control, but were sporadic in nature and associated with epithelial defects.

CONCLUSIONS

Clusters of DLK may be related to endotoxins released from gram-negative biofilms in sterilizer reservoirs. We experienced an outbreak of DLK affecting 52 patients and isolated B. pickettii from the sterilizer reservoir. Epidemiologic investigation showed that biofilm control in the sterilizer reservoirs was associated with a significant reduction in the development of DLK. We encourage any clinics that experience a cluster of DLK to consider microbiologic and epidemiologic investigation for the effectiveness of sterilizer biofilm control.

Eye care for patients receiving neuromuscular blocking agents or propofol during mechanical ventilation

BACKGROUND

The presence of a corneal reflex and the ability to maintain eye closure are instrumental in protecting the cornea. Use of neuromuscular blocking agents or propofol can result in impaired eyelid closure and loss of corneal reflex, leading to corneal exposure. The cornea is then at risk for drying, infection, and scarring, which may lead to permanent visual loss.

OBJECTIVES

To determine whether applying artificial tear ointment to the eyes of paralyzed or heavily sedated patients receiving mechanical ventilation decreases the prevalence of exposure keratitis more than does passive closure of the eyelid.

METHODS

A prospective, randomized control trial was done. The sample was 50 patients in the intensive care unit receiving either neuromuscular blocking agents or propofol during mechanical ventilation. In each patient, artificial tear ointment was applied to one eye; passive closure of the eyelid was used for the other eye (control eye).

RESULTS

Nine patients had evidence of exposure keratitis in the untreated eye, and 2 had corneal abrasions in both the treated and the control eyes. The remaining 39 patients did not have corneal abrasions in either eye. Use of the artificial tear ointment was more effective in preventing corneal exposure than was passive eyelid closure (P = .004).

CONCLUSIONS

Eye care with a lubricating ointment on a regular, set schedule can effectively reduce the prevalence of corneal abrasions in patients who are either paralyzed or heavily sedated and thus can help prevent serious complications such as corneal ulceration, infection, and visual loss.

Early release of third-degree eyelid burns prevents eye injury

Burns to the eyelids occur in more than 20 percent of flame injuries and can lead to ocular damage and even blindness. Burn wound contracture can cause ectropion of the eyelid, resulting in exposure keratitis, corneal ulcers, and conjunctivitis. At our hospital, early eyelid release and grafting has made a significant difference in the long-term outcomes of third-degree eyelid burns; however, the question of just how early eyelid release and grafting should take place is an unresolved issue. Fifty-seven children with third-degree eyelid burns were reviewed; 17 had eyelid release within 7 days of receiving eyelid burns and 40 had a delay in eyelid release of more than 7 days after injury. Analysis was by chi-square with the Yates continuity correction or Fisher's exact test when appropriate. Corneal ulcers developed in 2 of 17 of the early eyelid release of third-degree burns, compared with 25 of 40 delayed releases (p = 0.001), exposure keratitis in 3 of 17 early releases, and 30 of 40 in delayed release (p = 0.000); conjunctivitis was identified in 1 of 17 early releases and 14 of 40 delayed eyelid releases (p = 0.025). Release of eyelid burns within 7 days of injury can prevent the development of exposure keratitis, progressive conjunctivitis, corneal ulceration, and the need for corneal surgery. We suggest that early release and grafting should be the treatment of choice for children and young adults with third-degree burns to the eyelids.

Lactoferrin protects against UV-B irradiation-induced corneal epithelial damage in rats

PURPOSE

Lactoferrin supplementation suppresses ultraviolet light B (UV-B)-induced oxidation of cultures of human corneal epithelial cells. To investigate the protective effect of lactoferrin containing eyedrops against UV-B-induced corneal damage in vivo, we examined lactoferrin efficacy in a rat UV-B keratitis model.

METHODS

Sprague-Dawley rats were irradiated with >10 kJ/m2 after anesthetization, and then corneal epithelial defect was observed at 24 h postirradiation. The pre- or postapplication of vehicle or lactoferrin-containing eyedrops was performed, and then corneal epithelial damage was scored based on fluorescein staining.

RESULTS

Posttreatment with lactoferrin did not inhibit the extent of corneal damage and did not affect wound healing. However, pretreatment by topical application of lactoferrin suppressed development of a corneal epithelial defect induced by UV-B irradiation in rats.

CONCLUSION

These results suggest that the presence of lactoferrin in human tear fluid may inhibit UV-induced corneal epithelial damage.