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Biomedical subjects

D J Schanzlin

Publications and source records attributed to D J Schanzlin.

At least 19 recordsLinked to original sources
PubMed1992

Visual outcome after penetrating keratoplasty with double continuous or combined interrupted and continuous suture wound closure.

We reviewed the consecutive records of 296 patients who underwent corneal transplantation at our institution to compare visual outcome between those who underwent double continuous suture wound closure and those who underwent a combination of interrupted and continuous suture wound closure. Of 156 patients on whom one of these closure techniques was performed, 33 patients satisfied our inclusion and exclusion criteria. Visual outcome between the two groups was compared at three, six, and 12 months. We found significant differences (P less than .05) in average corneal curvature and refractive spherical equivalents (steeper and more myopic, respectively, for double continuous suture wound closure); keratoscopic astigmatism, refractive cylindrical error; and average number of postoperative visits (greater for combined interrupted and continuous suture wound). Visual acuity without correction was significantly better at three months in the group that received double continuous sutures (P = .026). We found no marked difference in best-corrected visual acuity, frequency of graft rejection, requirement for contact lens fit, ratio of refracted vs potential visual acuity, or intraocular pressure. Patients who underwent double continuous suture closure had more rapid visual rehabilitation, had steeper corneas, and less astigmatism than patients who underwent the combined technique suture closure.

Aged↗
PubMed1992

Efficacy of tobramycin-soaked collagen shields vs tobramycin eyedrop loading dose for sustained treatment of experimental Pseudomonas aeruginosa-induced keratitis in rabbits.

We compared the efficacy of a fortified tobramycin-soaked collagen shield to the efficacy of a single loading dose (four 50-microliters drops) of fortified tobramycin eyedrops in the treatment of New Zealand White rabbits with Pseudomonas aeruginosa-induced keratitis. Eyedrop loading-dose efficacy was evaluated with and without lateral tarsorrhaphy. Six hours after a single treatment, significantly fewer Pseudomonas colonies were present in the corneas of all three drug-treated groups as compared to the number of colonies in the corneas of balanced salt solution-treated control rabbits (P less than .006). Although no significant difference was observed between any of the drug-treated groups, lateral tarsorrhaphy was associated with a greater than tenfold decrease in the number of colony-forming units (P = .073). We found no significant difference in efficacy between a collagen shield presoaked in tobramycin, and a single loading dose of tobramycin eyedrops, in the treatment of rabbits with P. aeruginosa-induced keratitis.

Administration, Topical↗
PubMed1992

Fibrin-enmeshed tobramycin liposomes: single application topical therapy of Pseudomonas keratitis.

Treatment of bacterial keratitis requires frequent application of topical antibiotics. We studied the efficacy of a single topical administration of tobramycin incorporated in large multivesicular liposomes and enmeshed in a fibrin sealant on rabbit corneas infected with Pseudomonas aeruginosa. One cornea each of 25 New Zealand albino rabbits was infected with P. aeruginosa. Twenty-four hours later, the animals were randomly divided into five groups of five. Group A received single hourly drops (50 microliters) of fortified tobramycin (14.5 mg/ml, total of 17.4 mg). Group B received a single topical application of 3.5 mg tobramycin, in 0.1 ml multivesicular liposomes, enmeshed in a fibrin sealant with an overlaying bandage contact lens. Group C was treated in the same manner as group B without the addition of fibrin sealant. Groups D and E served as nondrug-treated controls, with group D receiving topical fibrin-enmeshed liposomes devoid of tobramycin and group E receiving hourly topical balanced salt solution (BSS) drops. All animals were killed 24 h after initiation of therapy. Significantly fewer colonies of Pseudomonas were present in corneas of all three treated groups, as compared with the two nondrug-treated control groups (p less than 0.02). There were significantly fewer colonies of Pseudomonas in groups A and B as compared with group C (p less than 0.02). No significant difference was noted between a single administration of topical fibrinen-meshed tobramycin-encapsulated liposomes (group B) and 24 doses of hourly fortified topical tobramycin (group A, p greater than 0.05). Tobramycin-encapsulated megaliposomes may serve as a useful adjunct in treatment of Pseudomonas keratitis.

Administration, Topical↗
PubMed1992

Variations in corneal wound healing after radial keratotomy: possible insights into mechanisms of clinical complications and refractive effects.

Ultrastructural and histopathologic analysis was performed on three human corneal specimens for variable and complicated refractive outcomes 1-2 years after radial keratotomy. Specimens were obtained immediately postsurgery after microkeratome resection with homoplastic lamellar keratoplasty (two cases) and penetrating keratoplasty (one case) for correction of glare, severe astigmatism, overcorrection, and/or double vision. All three cases showed variability of wound healing and delayed corneal wound healing sites; epithelial retention cysts, and/or absence of stromal scar collagen that was not dependent on the length of time after surgery. Two of the three radial keratotomy specimens also contained extensive duplication of the superficial corneal epithelial basal lamina. When present, the thickened basal lamina (3-6 microns in thickness) was seen between all incisions evaluated and appeared to extend from the central optical zone out to the periphery of the lamellar button. The one full-thickness keratoplasty specimen showed focal loss of underlying endothelial cells with occasional migrating cells seen by scanning electron microscopy. These data support previous findings that delayed corneal wound healing with epithelial retention cysts remains the most common histopathologic alteration after radial keratotomy. The effects of variations and delay in wound healing between individuals could explain the lack of predictability of refractive outcome and continuing refractive instability in long-term follow-up after single or repeat radial keratotomy surgeries.

Adult↗
PubMed1991

Vision research in departments of ophthalmology. An Association of University Professors of Ophthalmology perspective.

A research committee of the Association of University Professors of Ophthalmology disseminated a survey questionnaire to determine the state of research in departments of ophthalmology across the United States. The questionnaire contained 71 questions that were designed to assess attitudes and trends within members' departments and to solicit suggestions from the membership. Of the 145 members and affiliates queried, 140 responded. While the results of the survey indicate significant diversity among departments, departmental chairpersons view research as a major priority in the goals of their departments, and they envision maintenance or expansion of research over the next decade. The survey results have been collated and serve now as the basis for this Association of University Professors position article.

Humans↗
PubMed1991

New cryoprotectant for cryorefractive surgery.

Cryorefractive surgeries, keratomileusis, keratophakia, and epikeratophakia cause destruction of keratocytes, which may result in postoperative corneal haze. We examined the effects of two cryoprotectants on keratocyte survival following freeze injury. We compared the ability of CPTES and the standard cryoprotectant KM-26 to prevent keratocyte death by altering the length of time corneal tissue was exposed to the cryoprotectant. When corneal stroma was immersed in CPTES for five minutes prior to freezing, 66.5% of the keratocytes survived; when tissue was immersed in KM-26 for the same length of time, 27.5% survived (P less than .01). Immersion for one to 30 minutes in CPTES prior to freezing produced keratocyte viabilities that were 40% to 80% of those of fresh, unfrozen tissue; immersion in KM-26 produced keratocyte viabilities of 20% to 60%. We compared the ability of these cryoprotectants to reduce corneal haze following freeze injury using our rabbit model of lamellar keratoplasty. The postoperative data were comparable to those in the cell culture experiments. Based on our findings in rabbit corneas, a cryoprotective medium such as CPTES may promote cell survival and thereby speed recovery from cryorefractive procedures in humans.

Animals↗
PubMed1991

Recurrent corneal erosion: pathology of corneal puncture.

Recurrent corneal erosion is a difficult disorder to treat. Despite conventional therapy, some patients continue to have episodes of erosion. Recent literature suggests the efficacy of corneal puncture, which is thought to induce adherence of the epithelium and basement membrane to the anterior stroma. We performed multiple corneal punctures with 23-, 25-, 27-, and 30-gauge needles on one patient who underwent penetrating keratoplasty 7 weeks later. We found that an insertion depth of 0.1 mm was sufficient to cause the production of new basement membrane and fibrocytic reaction in the anterior stroma. Analysis of the pathologic specimen supports the use of the larger 23- and 25-gauge needles, and cautions against the use of small gauge needles, especially 30-gauge, for this procedure.

Basement Membrane↗
PubMed1991

Tobramycin liposomes. Single subconjunctival therapy of pseudomonal keratitis.

The authors compared 24 doses of hourly topical fortified tobramycin (Group A) therapy with a single subconjunctival administration of multivesicular megaliposome-encapsulated tobramycin (Group B) and free subconjunctival tobramycin (Group C) in treating a rabbit model of keratitis caused by Pseudomonas aeruginosa. One cornea each of 50 rabbits was infected with P. aeruginosa for 24 hr. The animals then were divided randomly into five groups of ten each. Groups A, B, and C were treated as described. Group D received liposomes without tobramycin and Group E, hourly balanced salt solution. Significantly fewer Pseudomonas colonies were present in the corneas of all three drug-treated groups (A, B, and C) compared with the two control groups (D and E) at 24 hr (P less than 0.005). Significantly fewer Pseudomonas colonies were present in Groups A and B compared with Group C (P less than 0.02). No significant difference was noted between Groups A and B (P = 0.30). Tobramycin encapsulated in megaliposomes may be useful in treatment of pseudomonal keratitis.

Administration, Topical↗
PubMed1990

A comparison of en face and tangential wide-area excimer surface ablation in the rabbit.

We used an argon fluoride excimer laser (193 nm) to perform anterior corneal surface ablation in New Zealand white rabbits (25 eyes) using both en face and tangential methods. We followed up the animals for 90 days using slit-lamp photography and pachymetry at predetermined intervals. We also examined selected tissues with scanning electron microscopy and transmission electron microscopy. Immediate and subsequent examinations revealed significant differences in clarity between the two groups. When viewed through slit-lamp microscopy, the rabbits undergoing the en face method exhibited hazy corneas and irregular surfaces, whereas the corneas that underwent tangential keratectomy demonstrated less haze and fewer surface irregularities. Through histologic study and electron microscopy, we corroborated this finding. At 30 days, there was a statistically significant difference in clarity between en face--treated corneas and those treated tangentially.

Animals↗
PubMed1990

Long-term storage of frozen lenticules for cryorefractive surgery.

We studied freezing rates, cryoprotectants, and storage times on keratocyte viability, using rabbit corneal buttons incubated in either KM-26, CPTES, K-Sol, or TC 199 for 30 minutes at 4 degrees C. Using a controlled freezing rate (2 degrees/min to -40 degrees C), viabilities were 69 +/- 7% for KM-26, 113 +/- 21% for CPTES, 0.1 +/- 0.08% for K-Sol, and 0 +/- 0% for TC 199. The KM-26 and CPTES were further studied in corneas stored one to 30 days at -80 or -196 degrees C; CPTES had a better cryoprotective efficacy over one, three, and seven days of -80 degrees storage, and at liquid nitrogen storage temperature (-196 degrees) over one, 14, and 30 days storage. The findings demonstrate the superiority of CPTES. It provides better viability than KM-26 under similar conditions, and may enable long-term frozen storage of lenticules for later use in cryorefractive surgeries, with minimal loss of keratocyte viability.

Animals↗
PubMed1989

Oral acyclovir reduces the incidence of recurrent herpes simplex keratitis in rabbits after penetrating keratoplasty.

To determine if acyclovir sodium prevents postoperative herpes simplex virus type 1 (HSV-1) recurrences, 21 rabbits harboring latent HSV-1 underwent uniocular autograft penetrating keratoplasty. All operated-on eyes were treated with topical and subconjunctival dexamethasone sodium phosphate. Ten of the 21 rabbits also received oral acyclovir (intravenous acyclovir was given at the time of surgery). Postoperatively, 9 (82%) of 11 operated-on eyes in rabbits not treated with acyclovir had positive HSV-1 ocular cultures. In acyclovir-treated rabbits, however, none of the 10 operated-on eyes had positive ocular cultures. In addition, 9 (82%) of 11 of the operated-on eyes had geographic ulcers develop in the non-acyclovir-treated rabbits, compared with 1 (10%) of 10 in the acyclovir-treated rabbits. Finally, stromal keratitis appeared in 5 (56%) of 9 of the operated-on eyes in non-acyclovir-treated rabbits and 1 (12%) of 8 of the operated-on eyes in acyclovir-treated rabbits. The results of this study indicate that acyclovir significantly lowered the incidence of HSV-1 ocular shedding, geographic ulceration, and stromal keratitis in a rabbit autograft penetrating keratoplasty model.

Acyclovir↗
PubMed1988

Early changes in refractive error following radial keratotomy.

One hundred twenty-six eyes that had undergone radial keratotomy were analyzed to assess the early changes in refractive error after surgery. Between two weeks and three months, 38% of eyes became more myopic by less than 1 diopter (D), 34% by 1.00 to 1.87 D, and 25% by 2.00 to 3.50 D. Four eyes (3%) had a decrease of 0.25 to 1.25 D. The average increase between two weeks and three months was 1.31 D (SD, 0.9 D). To decrease this change, 15 eyes were semi-pressure patched at night and treated with topical steroids for four weeks following surgery. The average change between two weeks and three months in these eyes was 0.3 D (SD, 1.0 D). This retrospective study suggests that semi-pressure patching after surgery may be useful for eyes that are undercorrected or overcorrected by less than 1 D.

Humans↗
PubMed1988

Electrosurgical keratoplasty. Clinicopathologic correlation.

A patient with keratoconus who could not tolerate a contact lens underwent electrosurgical keratoplasty. Postoperatively, the central cornea was markedly flattened, but five weeks later the central steepening had recurred. Six months after the procedure, a penetrating keratoplasty was performed. Pathologic examination of the corneal button revealed an intact epithelium and basement membrane. Bowman's membrane was completely destroyed in the treated areas. Stromal scarring extended to involve the anterior two thirds of the corneal stroma. The collagen in this area was contracted and folded. The keratocytes and stromal collagen of the posterior third of the cornea were normal by light microscopy. Descemet's membrane and the endothelium also were normal. Despite the short-lived flattening of corneal topography, this procedure dramatically altered the stromal collagen in the anterior two thirds of the cornea.

Adult↗
PubMed1988

Immunoglobulin deposition in the cornea after application of autologous serum.

A 47-year-old man with a history of multiple corneal allografts for recurrent herpes simplex keratitis developed a subtotal nonhealing corneal epithelial defect. The patient was treated with hourly drops of autologous serum. A ringlike infiltrate was subsequently observed, followed by reepithelialization of the graft. The patient later suffered allograft rejection of the cornea and recurrence of the epithelial defect, and a repeated penetrating keratoplasty was performed. Examination of the excised button demonstrated a total epithelial defect, changes compatible with allograft rejection, and, in addition, eosinophilic granular deposits within the superficial corneal stroma that corresponded to the "immune ring" observed clinically. Immunoperoxidase staining was positive for IgG, IgM, IgA, and kappa and lambda light chains. These pathologic changes lend credence to the hypothesis that the precorneal tear film may be a source of immunoglobulin that becomes deposited within the stroma.

Cornea↗
PubMed1988

Morning-to-evening change in refraction, corneal curvature, and visual acuity 2 to 4 years after radial keratotomy in the PERK Study.

The authors previously reported morning-to-evening changes in ophthalmic measurements at 3 months and at 1-year after radial keratotomy in a self-selected group of patients in the Prospective Evaluation of Radial Keratotomy (PERK) study. Fifty-two patients included in the earlier study were examined again between 2 1/2 and 4 years after surgery before 10:00 AM and after 5:30 PM on the same day to determine if the changes persisted beyond 1 year after surgery. Between the morning and evening examinations, 31% of the eyes had an increase in minus spherical equivalent power of the manifest refraction of 0.50 to 1.50 diopters; 12% had a change in cylinder power of 0.50 to 1.00 D; 19% had a decrease in uncorrected visual acuity of two to five Snellen lines; and 29% showed central corneal steepening by 0.50 to 1.00 D. Thus, in some patients, morning-to-evening fluctuation persisted until 2 1/2 to 4 years after radial keratotomy.

Circadian Rhythm↗
PubMed1988

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↗
PubMed1988

Chronic alcoholism and microbial keratitis.

In a series of 227 consecutive, non-referred patients with microbial keratitis an analysis of the accumulated hospital records showed that one-third were associated with chronic alcoholism. The diagnosis of alcoholism was usually unsuspected on admission to hospital. The microbial pathogenesis in these patients was distinctive; coagulase-negative staphylococci, alpha- and beta-streptococci, moraxellae, enteric Gram-negative bacilli, and polymicrobial infections were unusually prominent. Pseudomonas aeruginosa was uncommon. Trauma, exposure, bullous keratopathy, other external ocular diseases, and self-neglect were the major recognised predisposing causes. The nutritional, toxic and immunological sequelae of alcoholism may also have been contributory. Ophthalmologists should be alert to the diagnosis of chronic alcoholism in their patients. Chronic alcoholism may be an important and underrated risk factor for microbial keratitis.

Alcoholism↗