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Biomedical subjects

G A Stern

Publications and source records attributed to G A Stern.

At least 37 records · Page 2Linked to original sources
PubMed1998

Contact lens associated bacterial keratitis: past, present, and future.

PURPOSE: This paper reviews the medical history of the pathogenesis of contact lens related bacterial keratitis and its relationship to the development of successive generations of soft contact lenses. METHODS: The Methods section presents a literature review and the author's personal experience. RESULTS: Bacterial corneal infections have been a significant complication limiting the overall success of soft contact lenses for visual correction. Experience with different types of lenses has pointed to specific causes for the frequency of infection. However, there has been a general understanding that the health of the patient's epithelium, the patient's lens care practices, and the hypoxic effects of overnight wear each significantly contribute to the development of corneal infection. CONCLUSIONS: A complete understanding of the pathogenesis of contact lens associated bacterial infection would allow the development of strategies to prevent infectious complications of lens wear. Progress appears to have been made with a trend toward fewer and less severe infections. As the possibility of a reasonably priced daily wear disposable lens with better oxygen transmissibility and surface modifications to limit deposits and bacterial adherence evolves, safer lenses will continue to be developed.

Contact Lenses, Hydrophilic↗
PubMed1996

Corneal anesthetic abuse and Candida keratitis.

PURPOSE: Topical corneal anesthetic abuse is a self-inflicted injury, causing profound corneal morbidity. Superimposed infection is an important complicating factor. The authors report four patients with confirmed topical anesthetic abuse of the cornea, in whom Candida keratitis developed. METHODS: A retrospective review of the medical records of four patients with confirmed topical corneal anesthetic abuse and fungal keratitis. RESULTS: A 21-year-old woman, two 28-year-old women, and a 35-year-old man were included in the study. All these patients sustained a corneal injury, prompting the chronic use of topical anesthetics (0.5% proparacaine hydrochloride in 3 patients, and 0.5% tetracaine hydrochloride and 0.4% benoxinate hydrochloride in the other). Corneal findings included epithelial defects in all patients, focal infiltrate in one patient, and ring-shaped stromal infiltrate in three patients. Topical anesthetic was discontinued, all patients initially were treated empirically with antibacterial agents, and three patients received topical corticosteroids. Subsequent corneal cultures grew Candida spp, Candida albicans specifically in three patients, and local and systemic antifungal therapy was started. Corneas in two patients re-epithelialized; a conjunctival flap was performed on another patient with a descemetocele; and the remaining patient was lost to follow-up, although repeat fungal cultures yielded no growth. CONCLUSIONS: Corneal superinfection with Candida may occur during topical anesthetic abuse. Therapy includes discontinuation of the anesthetic and institution of antifungal therapy.

Administration, Topical↗
PubMed1996

Inhibition of pseudomonal ulceration in rabbit corneas by a synthetic matrix metalloproteinase inhibitor.

PURPOSE: To evaluate the effect of the synthetic matrix metalloproteinase inhibitor, Galardin, on proteases produced by Pseudomonas aeruginosa (PA) and on a rabbit model of Pseudomonas keratitis. METHODS: Protease activities of culture broths from Pseudomonas strains PA-28 and W-186 were characterized in vitro by gelatin zymography and by digestion of Azocasein in the presence and absence of Galardin and the serine protease inhibitor, aprotinin. In a noninfectious in vivo experiment, sterile PA culture broth from W-186 was injected intrastromally into rabbit corneas that were treated topically with Galardin or vehicle, then evaluated clinically and histologically. In an infectious in vivo experiment, rabbit corneas were injected with washed PA-28, then treated topically with Galardin or vehicle and clinically scored. RESULTS: Gelatin zymography of culture broth from W-186 and PA-28 detected two proteases that were both inhibited by Galardin. Galardin reduced the digestion of Azocasein by both PA culture broths by 99%, whereas aprotinin did not significantly reduce the protease activity of PA-28 conditioned broth. Intrastromal injection of sterile W-186 culture broth caused rapid corneal destruction that was prevented by topical treatment with Galardin. Intrastromal injection of washed PA-28 bacteria resulted in progressive corneal melting that was significantly (P < 0.005) delayed, but ultimately not prevented, by topical treatment with Galardin. CONCLUSIONS: Pseudomonal protease activity in culture broth consisted predominantly of metalloproteinases and were effectively inhibited by Galardin in vitro. Topical treatment with Galardin prevented destruction of rabbit corneas by bacterial products present in culture broth, and it delayed corneal destruction after injection of PA bacteria. Galardin may be a useful adjuvant when corneal destruction proceeds despite prompt antibiotic treatment.

Administration, Topical↗
PubMed1995

Teaching ophthalmology to primary care physicians. The Association of University Professors of Ophthalmology Education Committee.

The evolution of our health care system toward managed care has placed primary care "gatekeeper" physicians in a position where they must examine and treat patients with diseases that are ordinarily treated by medical and surgical subspecialists. Many of these physicians may be poorly prepared to accept this new responsibility. The Association of University Professors of Ophthalmology (AUPO) has published a Policy Statement on Medical Student Education that suggests the minimum level of competence expected of general physicians when dealing with ophthalmologic problems. A recent survey of directors of residency programs in family practice, internal medicine, and pediatrics revealed that the training of primary care physicians (as opposed to academicians or subspecialists) has become a nearly universal programmatic goal. Most program directs believe that less than half of their residents meet the AUPO standard at the completion of medical school, and a significant minority do not meet the AUPO standard at the completion of their residency. An overwhelming majority of program directors believe that additional training in ophthalmology and other subspecialties should be incorporated into the training programs of primary care physicians. Ophthalmologists and other subspecialists should develop programs at the medical student level directed toward the education of primary care physicians, and should participate in the training of primary care physicians, as well as their own subspecialty residents. In the future, the primary care physician must be considered part of the "eye care team." Enhancing the ophthalmologic education of primary care physicians is in the best interest of quality patient care.

Family Practice↗
PubMed1995

Diagnosis and successful medical treatment of Acanthamoeba keratitis.

OBJECTIVE: To identify the methods that result in timely diagnosis and effective treatment of Acanthamoeba keratitis. METHODS: We retrospectively reviewed the medical records of 12 consecutive patients whom we treated for culture-proved Acanthamoeba keratitis in 14 eyes. RESULTS: Contact lenses were worn in 13 of 14 affected eyes and substandard methods were often used to care for them. The diagnosis was established in all patients by laboratory analysis of corneal scrapings; corneal biopsies were not required. Acanthamoeba organisms were identified on smears from 12 of 14 eyes with use of standard, nonfluorescent stains and recovered in culture from all patients by inoculating scrapings on nonnutrient agar overlaid with Escherichia coli. Eleven of 14 eyes were medically cured with a combination of antiamebic drugs, most commonly propamidine isethionate, neomycin sulfate, and clotrimazole. Topical corticosteroids were used in only one patient. Two of the three eyes that required therapeutic keratoplasty were not treated before surgery according to our usual protocol; the third required keratoplasty for treatment of a severe bacterial superinfection. Twelve of 14 eyes recovered 20/50 or better visual acuity. Bacterial superinfections were a serious problem, with a total of six superinfections occurring in three treated eyes. CONCLUSION: With timely diagnosis and medical treatment with a combination of antiamebic drugs and avoidance of topical corticosteroids, most cases of Acanthamoeba keratitis can be cured, with an excellent prognosis for visual recovery.

Acanthamoeba↗
PubMed1994

The clinical management of keratoconus: a 6 year retrospective study.

We conducted a retrospective analysis of the management of 118 eyes of 66 new patients presenting with keratoconus at the University of Florida from 1987 through 1992. Eyes were ultimately managed by one of three methods: glasses or no correction; contact lenses; or penetrating keratoplasty. The outcome of each management method was determined by evaluating initial and final vision and keratometry for each group. Twenty-one eyes received glasses or required no correction. Rigid gas permeable lenses, Dura-T style PMMA lenses, and specialty design gas permeable lenses were used to successfully fit 63 eyes. Twenty-eight eyes underwent penetrating keratoplasty (PK), and an additional six eyes were PK candidates. Factors associated with the need for PK included best corrected initial visual acuity of 20/40 or worse, average keratometry > 55 D, and the presence of apical scarring (P < 0.001).

Adolescent↗
PubMed1994

Elevation of transforming growth factor alpha in cat aqueous humor after corneal endothelial injury.

PURPOSE: To determine if a scrape injury to cat corneal endothelial cells increases the level of mitogenic proteins such as transforming growth factor alpha (TGF alpha) in aqueous humor. METHODS: Aqueous humor of cats was collected at 0, 2, 6, and 24 hours after wounding the endothelium by contact with a cannula tip. Aqueous humor samples collected from sham-wounded cats served as controls. Aqueous humor samples were analyzed for levels of protein, for mitogenic activity using incorporation of tritiated thymidine by cultures of bovine corneal endothelial cells, and for immunoreactive TGF alpha protein using a specific radioimmunoassay. RESULTS: The average protein level in aqueous humor obtained before wounding was low (0.5 mg/ml), increased 26-fold at 2 hours after injury (13 mg/ml), then progressively decreased at 6 hours (8 mg/ml) and 24 hours (2 mg/ml). Levels of mitogenic activity of aqueous humor samples collected 2, 6, and 24 hours after wounding were 2-fold, 2.5-fold, and 0.6-fold higher, respectively, compared to the level of mitogenic activity measured in aqueous humor collected before wounding (0 hours) or in aqueous humor collected from sham-wounded eyes. TGF alpha concentration in aqueous humor collected before endothelial wounding was low (6.8 ng/ml), increased 14-fold 2 hours after wounding (97.4 ng/ml), then progressively decreased at 6 hours (63.3 ng/ml) and 24 hours (35.5 ng/ml) after wounding. TGF alpha concentrations in aqueous humor collected from sham-wounded eyes at 2 hours (9.5 ng/ml) and 6 hours (5.3 ng/ml) were not significantly different from prewound levels. Detergent extracts of bovine corneal endothelial cells contained substantial levels of TGF alpha immunoreactive protein (20 ng/mg protein). CONCLUSIONS: Wounding of cat endothelium causes a rapid increase in mitogenic proteins in aqueous humor including TGF alpha, which may act by an autocrine mechanism to stimulate endothelial wound healing.

Animals↗
PubMed1993

Mass spectrometric studies of the toxaphene components 2-exo,3-endo,5-exo,6-endo,8,8,10,10-octachlorobornane (T2) and 2-exo,3-endo,5-exo,6-endo,8,8,9,10,10-nonachlorobornane (T12).

The electron capture negative ion mass spectra of the title compounds show prominent [M-Cl]- ions, and low-abundance ions formed by further elimination of HCl or Cl2. The electron ionization positive ion mass spectra are complex, but structurally informative fragmentations are observed. In particular, fragmentations involving elimination of C2H2Cl2, and not of C2H4, C2H3Cl, C2HCl3 or C2Cl4, indicate that two chlorines are bound to the C2-C3 and C5-C6 units of a norbornane skeleton. Furthermore, from M+., elimination of HCl is enhanced with respect to Cl., relative to toxicants A and B, which are major components of commercial toxaphene; this result suggests that one chlorine atom is bound to each of carbons 2, 3, 5 and 6. Both compounds have CHCl2 substituents. Several of the fragmentation pathways appear to terminate at ions that may be tropylium analogues.

Adipose Tissue↗
PubMed1993

Results of therapeutic penetrating keratoplasty.

PURPOSE: To determine the anatomic and visual results of therapeutic penetrating keratoplasty (PK) and its role in the management of corneal disease. METHODS: The authors reviewed the records of all of their patients who had undergone therapeutic PK over the past 9 years and evaluated each for the following criteria: cure of disease, graft clarity, and visual acuity. Patients were divided into seven categories: (1 and 2) bacterial and fungal keratitis, (3 and 4) herpetic keratitis, with and without inflammation, (5) acanthamoebic keratitis, (6) perforations due to keratoconjunctivitis sicca, and (7) other causes of perforation. RESULTS: In microbial keratitis, therapeutic PK eradicated the disease in all cases. Seventy-three percent of grafts for bacterial keratitis and 60% for fungal keratitis remained clear. A higher percentage of clarity was achieved when grafts were 9.0 mm or less. Seven patients with secondary endophthalmitis were cured with a surgical approach including therapeutic PK. In herpetic keratitis with active inflammation, only 36% of grafts remained clear, and inflammation recurred in 36%. All perforations due to post-herpetic persistent epithelial defects in "quiet" eyes were grafted successfully. In patients with severe keratoconjunctivitis sicca, eyes were anatomically stabilized in 83%, but all grafts failed because of complications from ocular surface disease. CONCLUSIONS: Therapeutic PK is valuable in the management of microbial keratitis that does not respond to antimicrobial therapy. Results are poorer for patients with herpetic keratitis, although selected patients respond to therapeutic PK when other methods of management have failed. Patients with perforations due to keratoconjunctivitis sicca have a uniformly poor prognosis for graft clarity.

Acanthamoeba Keratitis↗
PubMed1993

Drainage tube implants in the treatment of glaucoma following penetrating keratoplasty.

A retrospective review was undertaken to compare outcomes in 26 eyes that underwent penetrating keratoplasty (PKP) and drainage tube surgery (Molteno double-plate implant or Schocket procedure). Drainage tube surgery was performed either before PKP (10 eyes), after PKP (7 eyes), or at the same time as PKP (9 eyes). Mean follow up was 22 months. The average preoperative intraocular pressure (IOP) for all of the eyes was 31 mm Hg; 96% of them achieved a final IOP of less than 18 mm Hg (average, 14 mm Hg on a mean of 0.8 medications). Graft failure occurred in 11/26 (42%). Eight of these eyes were regrafted, and six of these eight have remained clear at a mean follow up of 22 months after regrafting. The overall PKP success rate, including the eyes that underwent repeat PKP, was 81%. Visual acuity remained stable or improved in 70% of the eyes.

Adolescent↗
PubMed1993

Enhanced healing of cat corneal endothelial wounds by epidermal growth factor.

PURPOSE: The authors investigated whether healing of cat corneal endothelial wounds could be enhanced in vivo by human epidermal growth factor (EGF). METHODS: EGF was administered in sodium hyaluronate to the anterior chamber of cats after an endothelial touch injury. Control contralateral eyes received sodium hyaluronate alone. At selected times after injury, the corneas were evaluated for thickness, the rate of endothelial wound closure, the endothelial cell density, any variation in cell size, the percentage of hexagonal cells, and endothelial cell mitosis. RESULTS: Two days after injury, endothelial wounds of eyes treated with EGF had healed an average of 65 +/- 4% of the initial 38.5 mm2 wound area; paired control eyes had healed an average of 59 +/- 4% (P < 0.05). Both EGF-treated and control wounds had resurfaced over 90% of the initial wound area on day 4 after injury, and the wounds were completely resurfaced by 7 and 14 days after injury in both treatment groups. On days 4 and 7 after injury, the EGF-treated corneas were 5% and 8% thicker (835 versus 796 microns and 786 versus 728 microns, respectively) than the paired control corneas (P < 0.03). On days 10 and 14 after injury, both EGF-treated and control corneas were 19% and 12% thicker, respectively, than prewound the corneal thickness (621 microns). Seven days after injury, the corneas treated with EGF had an average of 76 +/- 28% more (P < 0.05) endothelial cell nuclei labeled with tritiated thymidine compared with that of the paired control eyes (2472 versus 1543 labeled nuclei). Fourteen days after injury, the central endothelial cell density of EGF-treated corneas was an average of 38 +/- 11% higher than that of the paired control eyes (P < 0.01, 1708 versus 1235 cells/mm2). The percentage of hexagonal cells in the wound area was an average of 14 +/- 4% higher (P < 0.01) than that of the paired control eyes (82% versus 69%), and the coefficient of variation of the cell size for EGF-treated corneas was an average of 31% (P < 0.05) smaller than that of the paired control corneas (0.21 versus 0.29 [standard deviation]/mean cell size). CONCLUSIONS: A single intraocular application of EGF formulated in sodium hyaluronate after an endothelial cell injury significantly enhanced multiple parameters that are closely related to improved endothelial cell regeneration.

Animals↗
PubMed1992

Evaluation of corneal collagen shields as a drug delivery device for the treatment of experimental Pseudomonas keratitis.

PURPOSE: To clarify the role of corneal collagen shields as a drug delivery device for the treatment of bacterial keratitis, the authors studied the effectiveness of topical gentamicin treatment, with and without the use of corneal collagen shields, in a rabbit model of Pseudomonas keratitis. METHODS: Forty-eight New Zealand white rabbits were infected by injecting 500 colony-forming units (CFU) of Pseudomonas aeruginosa into the corneal stroma, and treatment was begun 24 hours later. A 13.6 mg/ml solution of gentamicin was topically administered during a 24-hour period. Collagen shields were soaked in gentamicin 13.6 mg/ml for 5 minutes before placing them on the cornea. Corneas were quantitatively cultured 1 hour after the treatment period ended. Six different groups of rabbits were tested, with the results analyzed as the mean log10 of bacterial CFU. RESULTS: An untreated control group had significantly more bacteria (7.96 +/- 0.74) than any of 5 treatment groups. No difference was found between groups given a loading dose of antibiotic drops at the beginning of treatment, either with (4.90 +/- 2.41) or without (6.25 +/- 0.54) an antibiotic-impregnated collagen shield. A group treated with a collagen shield augmented with gentamicin drops every 3 hours had fewer bacteria (1.52 +/- 1.82) than a group receiving drops alone (4.15 +/- 1.83) (P less than 0.05). However, treatment with a collagen shield supplemented with drops every 3 hours was not as effective as gentamicin drops administered every 30 minutes (no bacterial growth) (P less than 0.05). CONCLUSION: These results show that antibiotic-impregnated collagen shields should not replace traditional antibiotic drop therapy as the mainstay of treatment but may be a useful adjunct to treatment with topical antibiotics.

Animals↗
PubMed1992

Intraepithelial sebaceous carcinoma of the conjunctiva and skin of the eyelid.

The authors report a 65-year-old woman with a 10-year history of conjunctivitis and progressive loss of lashes due to widespread intraepithelial sebaceous carcinoma of the conjunctiva and skin of the eyelid. After surgery, serial sections of the entire conjunctiva and eyelids showed a single focus of invasive carcinoma in the bulbar conjunctiva, which probably arose from the epithelium. The absence of cilia on the affected lower lid was associated with neoplastic obliteration of the cilial orifices and low-grade, smoldering lipogranulomatous inflammation. This type of tumor-related alopecia is likely to masquerade as blepharitis because there is no identifiable tumefaction or clinical evidence of recurrent chalazia to suggest an underlying sebaceous carcinoma. The 10-year history of "conjunctivitis" before diagnosis indicates that intraepithelial sebaceous carcinoma may have a prolonged clinical course.

Aged↗
PubMed1992

Indications for and results of intraocular lens explantation.

We reviewed the medical records of 97 patients who had 101 consecutive intraocular lens (IOL) explantation procedures, with or without exchange, at the University of Florida Eye Center from January 1, 1983, to December 31, 1987. The majority of the removed IOLs were anterior chamber styles (53.9%), followed by iris-fixated lenses (33.7%). The most common indications for surgery included pseudophakic bullous keratopathy (PBK)--69%, uveitis-glaucoma-hyphema (UGH) syndrome--9%, and IOL instability--7%. The best visual outcome was seen in patients with IOL instability; 50% achieved 20/40 or better visual acuity. Forty one percent of patients with PBK, who had IOL explantation/exchange combined with penetrating keratoplasty, achieved 20/40 or better visual acuity. The poorest visual outcome was seen in patients with the UGH syndrome; 83% had a final acuity of 20/200 or worse. However, these patients achieved resolution of their pain and inflammation and better control of their intraocular pressure as a result of the surgery. Complications leading to IOL explantation tended to occur months to years after the original surgery in patients with closed-loop, semi-flexible anterior chamber lenses and iris-fixated lenses. Posterior chamber lenses were most often removed because of complications unrelated to the implant.

Aged↗