Intrastromal photorefractive keratectomy with a new optically coupled laser probe.

BACKGROUND: Intrastromal photorefractive keratectomy is a new procedure in which compact linear or area regions of the corneal stroma can be vacuolized, yielding changes in corneal curvature. METHODS: Diffraction-limited 1064-nanometer light pulses from a high rep rate Q-switched Nd-YAG laser were coupled through novel means into a probe with index-matched optical contact with the cornea. The resulting extremely reduced focal region initiated a plasma point that was free of shock front effects where tissue was reduced to liquid. This probe process was applied to the corneas of eye-bank eyes, and to living rabbit and primate eyes. The refractive effects were evaluated with slit-lamp microscopy, keratoscopy light and electron microscopy. RESULTS: Refractive effects similar to refractive keratotomy were observed immediately after treatment. Intrastromal highly localized vacuolized regions were observed at the depth of focus with variability of only 20 microns. The plasma point vacuoles were about 100 microns in diameter. Stromal material that occupied the vacuole space appeared completely reduced to liquid. The transition region between vacuole and normal tissue was less than 0.5 microns. The treatment vacuoles disappeared to the unaided eye 24 to 48 hours after treatment. CONCLUSIONS: Corneal refractive power can be achieved with intrastromal keratectomy.

Optically coupled technique for photorefractive surgery of the cornea.

A novel optically coupled laser probe and method that achieve noninvasive in vivo refractive flattening of the cornea of experimental eyes is described. This new refractive surgery concept is based on the highly localized photodisruption and/or photoablation of tissue within the stromal layer of the cornea without other layers' being affected. This is accomplished by a microscope probe that is optically index matched to the corneal surface, thereby achieving high numerical apertures. The sharp focal volume ensures highly localized energy deposition. Preliminary results in rabbit, primate, and human eye-bank eyes indicate significant permanent refractive changes with an exceptionally small amount of tissue modification.

Experimental ocular herpetic infections in rabbits. Treatment with 9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine.

A new acyclic nucleoside, 9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine (BIOLF-62), was found to be efficacious in the treatment of experimental ocular herpes simplex virus infections in rabbits. Complete healing of herpetic lesions occurred in a majority of animals after six days of topical treatment, three times per day. No toxic effects were observed in uninfected, drug-treated eyes. The BIOLF-62 treatment blocked viral replication in infected eyes sufficiently to make recovery of virus from any of the drug-treated eyes impossible, whereas virus was recovered from all placebo-treated eyes.

Intraocular antiviral penetration.

Aqueous levels of topically applied vidarabine monophosphate, trifluridine, and acyclovir were determined following topical administration in patients with normal corneas prior to cataract extraction. Meager levels in aqueous were found for vidarabine monophosphate, and none for trifluridine. Substantial levels of acyclovir were detected that were well within the therapeutic range of herpes simplex susceptibility.

A double-blind, multicenter clinical trial of acyclovir vs idoxuridine for treatment of epithelial herpes simplex keratitis.

Thirty patients randomized to the Acyclovir (ACV) group (26 with dendritic lesions, 4 geographic lesions) and 34 patients randomized to the idoxuridine (IDU) treatment group (26 dendritic lesions, 8 geographic lesions) with epithelial herpetic keratitis were evaluated for efficacy and adverse reactions in a multi-center, double-masked, randomized, stratified trial. Patients were treated with either 3% acyclovir ophthalmic ointment or 0.5% idoxuridine ophthalmic ointment five times a day for 14 days. The results of the trial indicated no significant difference between ACV and IDU as antiviral agents in the treatment of epithelial herpetic keratitis. The overall healing patterns of ACV and IDU adjusted for lesion type and prognostic factors, including presenting condition (initial or recurrent disease), duration of symptoms, prior ophthalmic steroid use, and positive pretreatment herpesvirus culture, as well as, the healing patterns within each lesion type adjusted for these factors, were not significantly different between the two treatment groups. There was no significant difference between the two groups in the frequency of development of deeper involvement. The only significant difference (P less than 0.01) in the frequency of development of adverse reactions was found in the incidence of development of superficial punctate epitheliopathy (IDU-42%, ACV-11%).

Use of portable vitrectomy instrumentation (VISC X) in the rural Guatemalan highlands.

In a rural mountain setting 20 patients with blinding ocular opacities were treated surgically with modern vitrectomy techniques. There were no intraoperative or postoperative complications unique to the isolated environment. Because of its compact portability, the VISC X proved to be an ideal vitrectomy instrument. In addition to plastic lid procedures, cataract extraction, and strabismus surgery, repair of retinal detachment and vitrectomy in selected cases has been added to the armamentarium of surgeons who are seriously involved in exporting ophthalmology to remote places.

Family-based suppressive intermittent therapy of hyperendemic trachoma with topical oxytetracycline or oral doxycycline.

A controlled double-blind stratified trial was carried out in a village in Southern Iran to assess the efficacy of family-based intermittent therapy of hyperendemic trachoma with topical oxytetracycline oily suspension twice daily for 7 days each month, or oral doxycycline 5 mg per kilogram of body weight once a month, in comparison with a control group which received vitamin pills once a month. In addition all other members of the selected children's families were also treated with the same regimen of therapy. The treatment was given for a period of 1 year by 3 field technicians, each responsible for one regimen of therapy. Examining the whole conjunctiva 4 months after the start of therapy, we observed no marked difference in the cure rate or the number of patients with moderate to severe trachoma between the groups treated with antibiotics and the control group. When treatment was continued for 12 months, a marked decrease in the prevalence of trachoma and in the grades of intensity of inflammatory responses as well as the positivity rate for Chlamydia trachomatis was observed in the groups treated with the topical oxytetracycline or oral doxycycline compared with the control group. While there was no marked difference between the efficacy of these 2 regimens of mass chemotherapy, the monthly intermittent therapy with a single dose of doxycycline offers the advantage of being more practical and less expensive for mass control of trachoma by requiring approximately one-tenth of the staff, transport, and other facilities required for the intermittent topical therapy with tetracycline eye ointment.

Herpetic ocular infections of childhood.

A series of 21 pediatric patients with ocular herpes simplex infections is reported. Two groups are presented: those with clinical primary herpes and those with documented recurrences. The corneal manifestations including clinical resistance to idoxuridine are presented. Stromal keratitis and visual loss were not marked in the primary group, but were difficult to prevent in those children with recurrences. The problems encountered in the overall management of children with herpetic keratitis are discussed.

In vitro and in vivo resistance of herpes simplex virus to 9-(2-hydroxyethoxymethyl)guanine (acycloguanosine).

In vitro passage of the Patton strain of herpes simplex virus type 1 (HSV-1-P) in the presence of acycloguanosine (ACG) led to the emergence of a highly drug-resistant strain (HSV-1-P-ACG-R). Over 1% of virions in 6 of 15 HSV strains tested were able to form plaques in the presence of 10 mumol of ACG on first exposure to the drug. Therefore, there exists among HSV strains a broad range of susceptibilities to ACG, and some strains contain particles which are partially resistant to ACG before ever contacting the drug. HSV-1-P-ACG-R was partially resistant to iododeoxyuridine; conversely, iododeoxyuridine-resistant virus was highly resistant to ACG. ACG-resistant virus (HSV-1-P-ACG-R) was equal to its parent strain (HSV-1-P) in susceptibility to adenine arabinoside. The HSV-1-P-ACG-R strain produced corneal lesions in rabbits which were completely refractory to topical treatment with 1% unguent ACG, but responsive to 3% ACG. Partially resistant HSV could be isolated from the eyes of rabbits infected with ACG-susceptible virus and treated topically with either 1 or 3% ACG for 6 days.

Ocular penetration of orally administered minocycline.

Minocycline administered orally with a loading dose of 200 mg followed by 2 doses of 100 mg 12 hours apart was found to produce adequate levels in the aqueous of patients with noninflamed eyes at the time of routine cataract extraction. The plasma to aqueous ratio was approximately 2:1. This study suggests the potential usefulness of minocycline in ocular infections that are due to sensitive bacteria.

Limulus lysate assay for early detection of certain Gram-negative corneal infections.

The limulus endotoxin assay has been previously demonstrated to be the most sensitive method available for detection of bacterial endotoxin. A commercially available form of limulus amoebocyte lysate was used in this study for detection of Gram-negative corneal infections in both experimental animals and in a group of nine patients. The limulus assay enabled rapid detection of Gram-negative infections in both the experimentally induced ulcers in rabbits and in the patients studied. False-positive reactions did not occur in corneal infections due to either Gram-positive bacteria, fungi, or herpes simplex keratitis. The limulus test proved to be more sensitive than examination of Gram-stained smears of corneal scrapings and became positive earlier than bacterial cultures. The limulus test was helpful in the diagnosis of partially antibiotic-treated corneal infections but could not be used to assess the response to antimicrobial therapy, since endotoxin persisted in the corneal scrapings for some time after initiation of therapy.

Role of corneal surgery in destructive corneal disease.

Surgery plays an integral role in the management of destructive corneal disease. There are many techniques for structural reinforcement of marginal corneal destruction. Therapeutic penetrating keratoplasty for severe cases of central corneal destruction can be an effective method of removing the bulk of diseased tissue, and securing histopathological confirmation of the diagnosis.

Swimmer's goggles for keratoconjunctivitis sicca.

Swim goggles with a moist chamber effect have been used successfully in seven patients with severe keratoconjunctivitis sicca unresponsive to the conventional means of therapy including artificial tears, mucolytics, and occlusion of the puncta. The longest follow-up is three years, the shortest six months. There have been no complications, and in all cases the patients have been subjectively and objectively improved.

Hemophilus orbital cellulitis and panophthalmitis simulating mucormycosis.

A 47-year-old uncontrolled diabetic presented with proptosis, pain, immobility of the globe, and a perforated corneal ulcer. The clinical impression of mucormycosis was erroneous. Hemophilus aegyptius was grown from the orbit, the vitreous and oropharynx. This is believed to be the first report of panophthalmitis due to this organism.

Vidarabine therapy of complicated herpes simplex keratitis.

Patients with active herpetic epithelial keratitis who had toxic reactions or were resistant to idoxuridine received vidarabine. Only one of 35 cases of herpetic epithelial keratitis without stromal disease failed to heal. Of 21 patients with active epithelial keratitis complicating stromal keratitis or uveitis. 11 had complete reepithelialization by day 14. Two patients were removed from the trial as treatment failures. The remaining cases healed in 21 to 48 days. In most instances the stromal keratitis was inactivated when the epithelial ulcer healed. In our patients treated with vidarabine, healing of herpes simplex epithelial ulcers was biphasic: Stage 1, progression from an active to an inactive viral ulcer, and Stage 2, complete reepithelialization.