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Biomedical subjects

J B Robin

Publications and source records attributed to J B Robin.

At least 19 recordsLinked to original sources

Corneal trauma: I--Classification and management.

Ocular trauma is common and frequently impairs vision. Injuries to the cornea account for approximately two thirds of ocular trauma. Appropriate detection, diagnosis, triage, and treatment decisions are needed in cases of corneal trauma to achieve maximum benefit for the traumatized patient. In this article, the prominent features of corneal trauma are reviewed, and a practical method of classification is presented to assist in management decisions.

Burns, Chemical

The spectrum of topography found in keratoconus.

In order to more completely understand the topographic changes associated with keratoconus we performed computer-analyzed, digitized, videokeratoscopy (CADVK) on 23 patients with clinically documented keratoconus, using the EH-270 Corneal Topographer (Visioptic, Houston, TX). The majority of analyzed eyes demonstrated the classic picture of a well defined zone of inferior to inferotemporal steepening. However, several other topographic patterns were noted, including: nasal, superior, and central steepening, as well as extension of the inferior steepening superiorly. Additionally, significant flattening was found in some portions of the cornea away from the cone, particularly in the superonasal quadrant. In all cases, the precise location and degree of steepening could be easily defined. Interestingly, for both typical and atypical topographic patterns, marked symmetry between eyes in each patient was noted. The use of CADVK may allow for a more thorough appreciation of the diverse and complex topographic abnormalities associated with keratoconus, information which could aid in contact lens management and design.

Adolescent

Results of penetrating keratoplasty for the treatment of corneal perforations.

We retrospectively analyzed 46 consecutive cases of penetrating keratoplasty performed as part of the treatment of corneal perforations; the minimum follow-up time after keratoplasty was 7 months. Predisposing conditions leading to perforation were an infectious keratitis in 26 eyes (57%), trauma in 14 eyes (30%), and corneal melt associated with ocular surface disorder in 6 eyes (13%). The success of penetrating keratoplasty in the treatment of corneal perforation depended on the timing of surgery and the cause of the perforation. If the perforation was traumatic in origin, delaying surgery for at least 3 months significantly improved the chances for graft success. Eighty percent of the penetrating keratoplasties delayed 3 months following primary repair of corneal laceration remained clear, and 50% of these patients had a visual acuity of 20/60 or better. If penetrating keratoplasties were performed for an infectious corneal perforation, grafts had a better chance to remain clear if surgery could be delayed. All grafts performed for corneal perforation associated with melting and ocular surface abnormalities failed.

Adolescent

Intravitreal biocompatibility of mussel adhesive protein. A preliminary study.

Mussel adhesive protein (MAP) is a new tissue adhesive derived from the sea mussel Mytilus edulis. Rabbit eyes were injected intravitreally with 1 mg of MAP or balanced salt solution in order to determine the intraocular effects of this new biologic tissue adhesive. Two concentrations of MAP were used: one was undiluted and the other was diluted to a concentration of 1:10. A marked cellular inflammatory response, compared with the control eyes, was seen clinically in the vitreous cavity of animals in which MAP was used undiluted. This response persisted for up to two weeks and was suggestive of inflammatory response to a foreign protein. When MAP was used at a dilution of 1:10, a mild transient cellular reaction was observed in the vitreous; this cleared after seven days. There was no increase in intraocular pressure, and none of the eyes developed cataract or optic nerve damage. Fluorescein angiography demonstrated no vascular leakage and electroretinography was normal in all of the eyes at two weeks. Histopathologic evaluation of the eyes at 7 and 14 days after injection revealed localized cellular inflammation in the vitreous and adjacent retina when MAP was used undiluted, but no reaction in the control eyes or in eyes injected with MAP at 1:10 dilution. This preliminary study suggests that MAP produces a marked intraocular inflammatory reaction when used at full concentration. By diluting the adhesive, a less severe inflammatory response was observed, which cleared with no complications.

Animals

The effect of collagen shields on rabbit corneal reepithelialization after chemical debridement.

We evaluated the effect of precarved collagen lenses on the kinetics of epithelial wound healing in an experimental model of corneal erosions. After induction of anesthesia, central corneal erosions of 5-mm diameter were created in New Zealand white rabbits using n-heptanol. Animals were randomly assigned either to the treatment group or to one of three control groups. Each animal in the treatment group received a precarved collagen shield made from porcine sclera. Immediately after creation of the corneal epithelial defects, topical fluorescein sodium was applied, and the corneas were photographed. Similar follow-up examinations were conducted at 5, 24, 30, 48, 72, and 96 hr after defect creation. Epithelial defect areas were calculated by projecting the photographic slides onto a computerized digitizing pad. Reepithelialization kinetics were compared for the four treatment groups. When initial wound size was taken into account, no significant difference between mean reepithelialization rates was noted. These results indicate that collagen lenses do not adversely affect the speed of corneal reepithelialization, and may, because of their documented biodegradibility and drug delivery capability, be useful in the clinical management of corneal epithelial erosions.

Analysis of Variance

The use of fluorescein-conjugated lectins for visualizing atypical mycobacteria.

We investigated the feasibility of using fluorescein-conjugated lectins for visualizing and differentiating two species of atypical mycobacteria. Pure cultures of Mycobacterium fortuitum and Mycobacterium chelonei were established, as was an experimental model of infectious keratitis involving these two organisms. Samples from the pure cultures and corneal scrapings were placed on glass slides, fixed, and incubated with one of a panel of 22 fluorescein-conjugated lectins. The slides were examined using an epifluorescence microscope. Fluorescein-conjugated concanavalin A brightly stained both species of atypical mycobacteria, in both the pure culture and experimental keratitis samples. Several additional fluorescein-conjugated lectins (wheat germ agglutinin, succinylated wheat germ agglutinin, Phaseolus vulgaris erythroagglutinin, and Psophocarpus tetragonolobus agglutinin) brightly stained M chelonei, but only moderately stained M fortuitum. These staining patterns are consistent with the known carbohydrate compositions of the cell walls of atypical mycobacteria and suggest that fluorescein-conjugated lectins may be useful for the visualization of these organisms in corneal infections.

Abscess

Herpes simplex keratitis in patients with acquired immune deficiency syndrome.

Acquired immune deficiency syndrome (AIDS) is associated with a wide spectrum of systemic and ocular infectious diseases. Little information is known about herpes simplex virus type 1 (HSV-1) keratoconjunctivitis in association with AIDS. The authors present six cases of recurrent HSV keratitis occurring in AIDS patients. Features of the herpetic keratitis in these patients included unilateral dendritic or geographic epithelial keratopathy; predilection for peripheral versus central corneal involvement; one to three recurrences per patient over a mean observation period of 17 months, with a median dendrite-free interval of 7 months; and a moderately prolonged clinical course with a median healing time of 3 weeks using topical antiviral therapy. Only one of six cases had stromal infiltrative involvement. These cases raise the question of whether the immunologic abnormalities associated with AIDS may affect the clinical characteristics and course of HSV keratitis.

Acquired Immunodeficiency Syndrome

Fluorescein-conjugated lectin visualization of fungi and acanthamoebae in infectious keratitis.

The authors investigated the efficacy of two fluorescein-conjugated lectins (FCLs), concanavalin A (F-ConA) and wheat germ agglutinin (F-WGA), to visualize microorganisms from clinical specimens with documented mycotic and acanthamoebic keratitis. Corneal scrapings from 18 patients with culture-proven keratomycosis and deparaffinized histopathologic specimens from five culture-proven cases of acanthamoebic keratitis were evaluated. The F-ConA provided consistently bright staining of the mycotic structures in each of the corneal scrapings. Both F-ConA and F-WGA stained acanthamoebic trophozoites and cysts in the histopathologic specimens. In both the corneal scrapings and the histopathologic specimens, the microorganisms were easily differentiated from background corneal cells and tissue. These staining patterns correlate well with the results from experimental studies, and with the known cell wall carbohydrate compositions for fungi and acanthamoebae. This study provides further evidence that FCLs (particularly F-ConA) may eventually become effective first-line stains for the visualization of microorganisms in specimens from ocular infections.

Acanthamoeba

Lack of toxicity of a topical recombinant interferon alpha.

We evaluated the potential ocular surface toxicity of a recombinant interferon-alpha (IFN alpha) preparation on rabbit eyes. Topical application of this interferon (1 x 10(6) U/day in each eye) for 6 weeks produced no discernible conjunctival or corneal abnormalities on clinical, histopathologic, or ultrastructural evaluations. We believe that this recombinant IFN alpha preparation is not toxic to the ocular surface of rabbits.

Animals

Preliminary evaluation of the use of mussel adhesive protein in experimental epikeratoplasty.

We have used a preliminary formulation of a bioadhesive in an experimental model of epikeratoplasty in rabbits. The adhesive, termed mussel adhesive protein (MAP), is a repeating decapeptide polymer that is the natural adhesive substance produced by the common blue mussel (Mytilus edulis) and is used here in conjunction with an enzymatic cross-linking agent. This study marked the first in vivo use of this material in adhering ophthalmic tissue planes. We used a simplified epikeratoplasty technique highlighted by freehand dissection of donor lenticules and host keratotomies. Approximately 10 microL of a combination of MAP and the cross-linking agent was applied directly to the host cornea and the donor lenticules were secured into the keratotomies using eight interrupted 10-0 nylon sutures. All of the sutures were removed 72 hours postoperatively. Eleven of the 15 animals retained their epikeratoplasty lenticules throughout the entire postoperative period. Four animals had initially intact lenticules that sloughed within the first postoperative week; this sloughing, we believe, was attributable to difficulties in tucking irregularly thickened lenticule edges into the keratotomy. In control animals that had lenticules secured with sutures alone, suture removal at 72 hours consistently produced immediate lenticule sloughing. Clinical examinations and histopathologic studies disclosed no untoward effects of the adhesive on the donor or host corneal tissue. We believe that this preliminary study indicates a potential adjunctive role for MAP in epikeratoplasty.

Animals

Rapid visualization of Acanthamoeba using fluorescein-conjugated lectins.

We investigated the efficacy of fluorescein-conjugated lectins (FCLs) for the rapid visualization of Acanthamoeba species. Cultures of Acanthamoeba castellani, Acanthamoeba culbertsoni, and Acanthamoeba polyphaga were established on nonnutrient agar plates supplemented with Escherichia coli. Maximal trophozoite populations were established four to five days after initial subculturing; mature cysts were routinely noted three to six days later. At various time points, trophozoites and/or cysts were harvested and suspended in Page's saline. Following a previously described protocol, samples of the suspensions were placed on glass slides and incubated with one of a panel of 14 FCLs. At the end of the incubation period, the slides were examined using an epifluorescence microscope. Concanavalin A brightly stained both cysts and trophozoites. Wheat germ agglutinin brightly stained cysts but only minimally stained trophozoites. These results suggest that FCLs may be useful for rapid visualization of Acanthamoeba organisms in corneal infections.

Acanthamoeba

Molteno implant for control of glaucoma in eyes after penetrating keratoplasty.

Seventeen patients (17 eyes) underwent implantation of a single plate Molteno implant for medically uncontrollable intraocular pressures after penetrating keratoplasty. Most of the eyes had extensive peripheral anterior synechiae, and 16 of 17 (94%) were pseudophakic or aphakic following keratoplasty. Other glaucoma procedures had been performed previously on 13 eyes: argon laser trabeculoplasty (one eye), trabeculectomy (seven eyes), transpupillary argon laser cyclophotocoagulation (three eyes), and cyclocryotherapy (three eyes). Follow-up ranged from 5 to 28 months (mean, 13 months). Three eyes underwent repeat Molteno implantation when intraocular pressure (IOP) was not satisfactorily reduced after the first procedure. Considering one eye with chronic hypotony as a failure, 12 of 17 eyes (71%) had IOPs of less than 21 mmHg at the time of the three most recent postoperative examinations after a single Molteno implant. Repeat implants in three eyes increased the number of eyes with IOPs of less than 21 mmHg to 14 (82%). Corneal allograft rejection after Molteno implantation occurred in seven eyes; two of these were successfully reversed with corticosteroid therapy. Three of the five eyes with irreversible graft rejection were regrafted, and two of these grafts have remained clear. Including the regrafted eyes, 13 eyes had clear grafts and controlled IOPs at the most recent postoperative examination. The Molteno implant may prove useful in the management of medically uncontrollable glaucoma following penetrating keratoplasty; however, there appears to be a substantial risk of postoperative graft rejection.

Adult

The lipids of chalazia.

The tissue contents of chalazia taken from five individuals were extracted for lipids and analyzed by TLC and GLC. Lipids found were sterol esters 9%, wax esters 0%, triacyl glycerols 4%, free cholesterol 11%, free fatty acids 2%, unidentified nonpolar material 3%, ceramides 7%, cerebrosides 3%, phosphatidyl ethanolamine 12%, phosphatidyl choline 20%, sphingomyelin 4%, lysolecithin 4%, unidentified polar material 18.0%. GLC of the sterol esters gave peaks corresponding to the C14, C16, C18 and C20 normal fatty acid esters of cholesterol. The free fatty acids were also of the normal kind. Thus, the lipids of chalazia contents show little similarity to the lipids of the meibomian gland. The latter has a large component of sterol esters and wax esters. Also the fatty acids of all the meibomian gland ester lipids have significant amounts of iso- and anteisobranching in contrast to the chalazia lipids. Chalazia lipids more closely resemble the lipids of membranes of phagocytic cells with a large cholesterol content.

Adolescent

Corneal allograft rejection in a pregnant woman.

We report a case of corneal allograft rejection that occurred in a gravid woman 1 year following transplantation. This is the first report, to our knowledge, of corneal allograft rejection occurring in a pregnant woman.

Acanthamoeba

Post-traumatic and postoperative endophthalmitis: a comparison of visual outcomes.

We retrospectively studied 50 consecutive cases of exogenous endophthalmitis treated between 1972 and 1985. Twenty-two of these cases occurred after penetrating ocular trauma and the remaining 28 followed ocular surgery. Thirty-two (64%) of the cases were culture-positive. A wide variety of organisms were identified in the post-traumatic cases, while the isolated agent in the majority of postoperative cases was Staphylococcus epidermidis. Twenty-nine of the 50 patients received treatment with vitrectomy and intraocular antibiotics; of these, 14 (48%) achieved final visual acuities better than or equal to 20/400. Of the 21 patients who were treated with parenteral, topical, and subconjunctival antibiotics alone eight (38%) reached this same final visual acuity. Culture-negative cases, postoperative cases, and cases treated with vitrectomy and intraocular antibiotics were associated with improved visual outcomes.

Adolescent