Immunofluorescent staining and corneal sensitivity in patients suspected of having herpes simplex keratitis

[Recurrent herpetic erosion of the cornea: diagnosis, treatment and prevention of recurrences]

A group of patients was found to have a special form of recurrent corneal erosion caused by types I and II herpes virus. This form represents an independent form of ophthalmic herpes - herpetic recurrent erosion (HRE) of the cornea. The herpetic etiology of recurrent corneal erosion was confirmed by the immunofluorescence study of scraping from the conjunctiva, which revealed a high concentration of the herpes simplex virus antigen. Treatment of patients (171 patients, 182 eyes) with HRE included 2 consecutive stages: stage I - relief of acute symptoms of the disease with the help of conservative treatment (instillations of interferon inducers, autologous serum, corneal protectors, tear substitutes, use of therapeutic soft contact lenses); in some cases, phototherapeutic keratectomy was used in the absence of the effect of conservative therapy, as well as in the localization of the focus in the optical zone. Stage II involved anti-relapse therapy based on the use of a Russian-produced herpes vaccine in the intercurrent period. After vaccination, observation for 2 years or more showed that 81.3% of patients achieved clinical recovery (complete cessation of HRE recurrences), 15.8% had a decrease in the frequency and severity of relapses, while 2.9% of patients did not respond to the treatment.

Morphological changes of corneal subepithelial nerve plexus in different types of herpetic keratitis

PURPOSE

We investigated by in vivo confocal microscopy alterations in the subepithelial nerve plexus in different types of herpes simplex keratitis (HSK).

METHODS

Seventeen patients (seven women and ten men, mean age 63.9 years) with a history of HSK were classified into three groups according to the classification of Herpetic Keratitis Infection Research Group. Slit-lamp examinations, corneal sensitivity measurements, and corneal in vivo confocal microscopy examinations [Rostock Corneal Module attached to the Heidelberg Retina Tomograph II (HRT II-RCM)] were performed.

RESULTS

Among the 17 cases, three were classified as epithelial type, ten as stromal type, and four as endothelial type HSK. The average corneal sensitivities were 11.41 ± 9.46 mm in the affected eyes and 43.24 ± 12.2 mm in controls. Decreases in three parameters in the affected eyes (long nerve-fiber density, nerve-branch density, nerve thickness) were statistically significant compared with controls. Decreases in the three parameters were more remarkable in the epithelial and stromal types than in the endothelial type.

CONCLUSION

The morphology of the corneal subepithelial nerve plexus may get gradually destroyed along with recurrent episodes of epithelial and stromal HSK. However, the destruction does not seem remarkable in the endothelial type of HSK, suggesting the possibility of a different route of virus recruitment in this type.

Is it safe to use topical NSAIDs for corneal sensitivity in Sjögren’s syndrome patients?

Sjögren's syndrome dry eye is an inflammatory disease accompanied by an impairment of the autonomous nervous system of the ocular surface. The therapy for this condition is shifting from the mere tear replacement to a more complex approach including an anti-inflammatory treatment. Clinical trials have evidenced that the use of NSAIDs is followed by a reduction of the ocular discomfort symptoms in dry-eye patients. However, sporadic case reports of corneal melting in dry-eye subjects who underwent surgical procedures has brought attention to the possible effect that NSAIDs may have on corneal sensitivity. Therefore, the effect of NSAID treatment on corneal sensitivity in normal subjects and in patients with dry eye was studied. The results of these trials seem to demonstrate that some NSAIDs, diclofenac in particular, have the effect of reducing corneal sensitivity both in normal subjects and in patients with dry eye. Therefore, NSAIDs should be used with caution in Sjögren's syndrome patients.

Evaluation of herpes simplex detection in corneal scrapings by three molecular methods

Herpes simplex virus (HSV)-1 keratitis (HSK) is a sight-threatening ocular infection with worldwide occurrence. A prompt laboratory diagnosis is often very useful. The purpose of this study was to evaluate molecular methods as rapid diagnostic tools compared with cell culture of HSK. Corneal scrapings from patients with clinically suspected HSK were tested by direct immunofluorescence assay (IFA) for HSV-1 antigen and by polymerase chain reaction (PCR) for HSV-1 DNA, and an attempt for viral isolation was performed on Vero cell line culture. Positive samples by cell culture were 20.8%, whereas PCR was positive in 29.2%, and IFA was positive in 33.3%. IFA had better sensitivity (80%) and negative predictive value (81.8%) than PCR (70% and 76.9%, respectively); however, PCR had better specificity (71.4%) and positive predictive value (63.6%). This indicates that a combination of cell culture, IFA and PCR constitutes the best set of tools for diagnosis of clinically suspected cases of HSK. Documented infection can be further assessed by cell-culture technique or PCR depending laboratory availability.

The effects of the topical administration of non-steroidal anti-inflammatory drugs on corneal epithelium and corneal sensitivity in normal subjects

PURPOSE

To study the changes in the corneal epithelium and corneal sensitivity of healthy subjects after the topical administration of non-steroidal anti-inflammatory drugs (NSAIDs; diclofenac, indomethacin, flurbiprofen and ketorolac) frequently used in ocular therapy.

METHODS

A double-masked parallel clinical study was undertaken on 90 subjects (45 men, 45 women; Caucasian; age 21-46 years, mean +/- SD 27.1 +/- 5 years). The subjects were divided into six groups: group 1 was treated with placebo, group 2 with 0.1% diclofenac, group 3 with 0.1% indomethacin, group 4 with 0.03% flurbiprofen, group 5 with 0.5% ketorolac and group 6 with 0.4% oxybuprocaine. One eye was randomly treated with the study drug and the fellow eye was treated with placebo. The medications were instilled four times, at 5 min intervals. Assessment of the corneal epithelium was carried out by vital fluorescein stain before instillation and 5, 15, 30 and 60 min after instillation of the last drop. Subjective burning sensation was assessed by asking participants to rate burning on a scale from 0 (none) to 3 (severe). After 1 week, assessment of corneal sensitivity was carried out by the Cochet-Bonnet method, repeating the above scheme of instillation and measurement times.

RESULTS

None of the study drugs, with the exception of oxybuprocaine, produced evident epithelial damage. All the drugs caused a mean burning sensation greater than the placebo. The diclofenac-treated group showed a statistically significant decrease in corneal sensitivity (p < 0.001) at the measurement carried out 15 min after instillation of the last drop and lasting up to the end of the study, when the corneal anaesthesia was similar to that induced by the topical anaesthetic treatment. No significant changes were demonstrated for the other NSAIDs when compared either with the placebo-treated eyes or with the fellow eyes.

CONCLUSIONS

Despite a similar mechanism of action and analgesic activity to the other NSAIDs tested, diclofenac was able to induce a reduction in corneal sensitivity. More studies are needed to determine the mechanism of action responsible for this effect.

Decreased corneal sensation as an initial feature of Acanthamoeba keratitis

BACKGROUND

Herpes simplex keratitis is the most common misdiagnosis in patients with Acanthamoeba keratitis, which is increasing in frequency and is associated with daily wear soft contact lenses. Both entities usually present as unilateral keratitis. The manifestations of superficial Acanthamoeba keratitis (i.e., unilaterality, dendriform appearance, positive response to antivirals, and decreased corneal sensation) increase the opportunity for misdiagnosis as herpes simplex keratitis. The authors have encountered six patients with Acanthamoeba keratitis in whom the correct diagnosis was delayed from 2 weeks to 3 months.

METHODS

All six patients underwent testing with the Cochet-Bonnet esthesiometer and extensive pharmacologic treatment for herpes simplex keratitis. Corneal scrapings were taken between 2 and 6 weeks after the initial examination.

RESULTS

In all six patients, corneal sensation was decreased significantly. Drug therapy was ineffective. Cultures were positive for Acanthamoeba. Five of six patients underwent penetrating keratoplasty.

CONCLUSIONS

Decreased corneal sensation has contributed to the misdiagnosis of Acanthamoeba as herpes simplex keratitis. Misdiagnosis results in delayed treatment and worse outcome. The authors found that significantly decreased corneal sensation is a frequent finding in early Acanthamoeba keratitis. Therefore, physicians should consider Acanthamoeba keratitis as an alternative diagnosis in patients with presumed herpes simplex keratitis with decreased corneal sensation.

Decrease in normal human corneal sensitivity with topical diclofenac sodium

We tested the effect of topical diclofenac sodium on corneal sensitivity in the human eye. Corneal sensitivity was measured in ten adult subjects with the Cochet-Bonnet esthesiometer before, and immediately after, applying one drop of diclofenac sodium 0.1% in one eye and one drop of diclofenac vehicle in the other eye. Application was repeated every five minutes for 20 minutes; then no more drops were applied, and corneal sensitivity was measured every 15 minutes until sensitivity measurements returned to baseline levels. Diclofenac sodium decreased corneal sensitivity significantly (P = .0001) in all ten subjects, compared with eyes treated with the vehicle. The effect of diclofenac sodium increased as additional drops were administered. After the drug instillation was stopped, corneal sensitivity returned to baseline measurements within less than an hour in all the subjects. Diclofenac sodium substantially lowers sensitivity in normal, unoperated-on human corneas; the vehicle has no measurable effect on sensitivity.