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Biomedical subjects

V S Nirankari

Publications and source records attributed to V S Nirankari.

At least 19 recordsLinked to original sources
PubMed2000

Topical mitomycin-C for subepithelial fibrosis after refractive corneal surgery.

OBJECTIVE: To determine the effectiveness of mitomycin-C (MMC), 0.02%, in preventing recurrence of corneal subepithelial fibrosis after debridement and/or keratectomy in patients who have undergone refractive corneal surgery. DESIGN: Noncomparative case series. PARTICIPANTS: Eight eyes of five patients with corneal subepithelial fibrosis who had previously undergone radial keratotomy (n = 4) or photorefractive keratectomy (n = 4). INTERVENTION: All eyes underwent epithelial debridement followed by a single intraoperative application of MMC (0.02%) for 2 minutes followed by saline irrigation. The eyes were then patched, or a bandage contact lens placed until epithelial healing was complete. MAIN OUTCOME MEASURES: Corneal clarity and best-corrected visual acuity (BCVA). RESULTS: In all cases, the cornea remained clear with no recurrence throughout the follow-up period (6-25 mos., mean, 13.8 mos). No adverse reactions were reported. BCVA improved in all cases. CONCLUSIONS: Subepithelial fibrosis can be a visually disabling condition after refractive corneal surgery. Topical application of MMC (0.02%) may be a successful method of preventing recurrence of subepithelial fibrosis after debridement.

Administration, Topical↗
PubMed1998

Decorin and biglycan of normal and pathologic human corneas.

PURPOSE: Corneas with scars and certain chronic pathologic conditions contain highly sulfated dermatan sulfate, but little is known of the core proteins that carry these atypical glycosaminoglycans. In this study the proteoglycan proteins attached to dermatan sulfate in normal and pathologic human corneas were examined to identify primary genes involved in the pathobiology of corneal scarring. METHODS: Proteoglycans from human corneas with chronic edema, bullous keratopathy, and keratoconus and from normal corneas were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), quantitative immunoblotting, and immunohistology with peptide antibodies to decorin and biglycan. RESULTS: Proteoglycans from pathologic corneas exhibit increased size heterogeneity and binding of the cationic dye alcian blue compared with those in normal corneas. Decorin and biglycan extracted from normal and diseased corneas exhibited similar molecular size distribution patterns. In approximately half of the pathologic corneas, the level of biglycan was elevated an average of seven times above normal, and decorin was elevated approximately three times above normal. The increases were associated with highly charged molecular forms of decorin and biglycan, indicating modification of the proteins with dermatan sulfate chains of increased sulfation. Immunostaining of corneal sections showed an abnormal stromal localization of biglycan in pathologic corneas. CONCLUSIONS: The increased dermatan sulfate associated with chronic corneal pathologic conditions results from stromal accumulation of decorin and particularly of biglycan in the affected corneas. These proteins bear dermatan sulfate chains with increased sulfation compared with normal stromal proteoglycans.

Adult↗
PubMed1994

Bilateral iridocorneal endothelial syndrome: case report and review of the literature.

We present the case of a 47-year-old woman with bilateral iridocorneal endothelial syndrome. The iridocorneal endothelial syndrome has heretofore been considered a unilateral disorder. However, a review of the literature and examination of the patient presented in this report indicate that bilateral occurrence of the iridocorneal endothelial syndrome is not uncommon. Consequently, it may be inappropriate to include unilaterality as a feature distinguishing the iridocorneal endothelial syndrome from similar conditions, most notably posterior polymorphous endothelial dystrophy.

Corneal Diseases↗
PubMed1993

Spontaneous ulcerative keratitis in immunocompromised patients.

We studied the occurrence of ulcerative keratitis in five eyes of four patients who were examined at the University of Maryland Hospital ophthalmology clinic over a 12-month period. All were young women who were intravenous drug abusers, with no known predisposing factors for ulcerative keratitis. Two patients had acquired immunodeficiency syndrome (AIDS), one was human immunodeficiency virus (HIV)-positive, and the fourth refused HIV testing. One had a corneoscleral limbus to corneoscleral limbus keratitis; three had inferiorly located corneal ulcers (bilateral in one patient with AIDS). Corneal cultures disclosed Capnocytophaga species in the corneoscleral limbus to corneoscleral limbus keratitis. The remaining ulcers were polymicrobial; cultures of three grew Candida albicans, cultures of two grew alpha-hemolytic streptococci, cultures of two grew Staphylococcus aureus, and culture of one grew Pseudomonas aeruginosa. Treatment with topical fortified antibiotics and antifungal agents resulted in complete healing in all four inferiorly located ulcers. The corneal ulcer became perforated and the eye was eviscerated. Histopathologic analysis of the eviscerated specimen disclosed acute keratitis with necrosis and no microorganisms.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Laser photocoagulation of experimental corneal stromal vascularization. Efficacy and histopathology.

BACKGROUND: Conventional treatment of corneal stromal vascularization is often inadequate. The authors developed a rabbit model of corneal stromal vascularization, treated it with laser photocoagulation, and then studied the histopathology. METHODS: A reproducible model of corneal stromal vascularization was developed in albino rabbits by injecting sodium hydroxide into the corneal stroma. Corneal stromal vascularization was produced in both eyes of 13 rabbits, and treated after stabilization at 5 weeks with 577-nm yellow dye laser in 1 eye of each rabbit. Seven rabbits were followed for 6 months with corneal angiography and photography, and the corneal stromal vascularization quantified with a grid. The other 6 rabbits were killed at 1, 4, 8, 24, 48 hours, and 6 days after laser photocoagulation and examined by light and transmission electron microscopy. RESULTS: Stable corneal stromal vascularization was observed in the anterior and midstroma for at least 6 months in the model. Laser photocoagulation reduced corneal stromal vascularization significantly compared with the controls (P < or = 0.05), resulting in 40.7% +/- 5.0%, 45.3% +/- 3.3%, and 34.9% +/- 5.2% (mean +/- standard error of the mean) reduction at 2, 4, and 6 months, respectively. Maximum inflammatory cell infiltrates were detected at 8 hours after laser photocoagulation, which diminished markedly at 6 days. The stroma of unlasered eyes showed no inflammatory cells and considerably more patent blood vessels than the lasered eyes. In the lasered eyes, transmission electron microscopy showed damaged vascular endothelial cells, extravasated erythrocytes, haphazardly arranged collagen fibrils, thrombus formation, and ghost vessels in the stroma. No damage was observed in the deep corneal stroma or endothelium in the lasered eyes. CONCLUSION: Laser photocoagulation is effective in reducing corneal stromal vascularization in this model for at least 6 months. It does not damage the deeper stroma or endothelium.

Animals↗
PubMed1993

Eyelid imbrication. An unrecognized cause of chronic ocular irritation.

BACKGROUND: Eighteen patients with chronic ocular irritation were examined over a 3-year period. All patients demonstrated papillary conjunctivitis and, occasionally, tarsal ulcers. Six also had floppy eyelid syndrome. Underlying every patient's symptoms was the overriding or imbrication of a lax upper eyelid on an often equally lax lower eyelid, allowing lower eyelid lashes to chronically rub the upper eyelid tarsal conjunctiva. METHODS: Chronic ocular irritation in five patients was managed with ocular lubricants. Two of these patients had floppy eyelid syndrome and required nightime shielding for nocturnal eyelid eversion. Thirteen patients underwent eyelid surgery to correct the overriding upper eyelid. Surgical procedures included full-thickness upper eyelid wedge resection, lateral canthal tendon plication, and lower eyelid horizontal shortening, using a tarsal strip procedure. RESULTS: Follow-up averaged 2.5 years. Symptomatology was adequately controlled in all patients. In addition to the five patients who received medical treatment for their symptoms, two with complicated ocular problems required continued ocular lubrication after surgery. Seven patients were successfully treated with eyelid shortening procedures and lateral canthal tendon plication. The remaining six patients underwent a variety of additional eyelid surgeries. All patients undergoing surgery had complete resolution of eyelid imbrication. CONCLUSIONS: Eyelid imbrication is a previously unrecognized cause of chronic ocular irritation. In this condition, eyelid laxity causes the upper eyelid to override the lower eyelid, allowing the lower eyelid to chronically rub and chafe the upper eyelid tarsal conjunctiva. In some cases, symptoms can be managed medically. More often, surgical intervention is required to correct eyelid laxity and prevent overriding of the upper eyelid.

Aged↗
PubMed1992

A new biaspheric contact lens for severe astigmatism following penetrating keratoplasty.

We conducted a study of 26 consecutive post penetrating keratoplasty patients (32 eyes) fit with a Boston Envision biaspheric rigid gas permeable contact lens with limited parameters. The lens was successfully worn by 81% of those fit. Eighty-nine percent of patients' eyes had visual acuity equal to or better than their best possible spectacle acuity, and lens related complications were minimal.

Adolescent↗
PubMed1991

Streptococcus sanguis survival in K-Sol. Comparison of gentamicin and the fluoroquinolone antibiotics.

Viridans streptococci are poorly covered by gentamicin sulfate in corneal storage medium. To evaluate possible antibiotic alternatives among the newer broad-spectrum fluoroquinolone antibiotics, we compared the survival of the viridans representative Streptococcus sanguis in K-Sol with gentamicin sulfate (100 mg/L), norfloxacin (250 mg/L), ciprofloxacin lactate (250 mg/L), ofloxacin (250 mg/L), or no antibiotic. At 23 degrees C, K-Sol with gentamicin produced a 2-log kill by 80 minutes. By comparison, only one of the others (norfloxacin) had achieved a 2-log kill by 4 hours. At 4 degrees C, all antibiotics differed little from the control, and none was superior to gentamicin.

Anti-Infective Agents↗
PubMed1990

Effects of epikeratoplasty on the host cornea. An experimental study.

The effects of epikeratoplasty on the host cornea was studied using albino rabbits. Eyes underwent midperipheral partial trephination alone (group I), midperipheral partial trephination and peripheral undermining (group II), midperipheral partial trephination and circular keratectomy (group III), and trephination, peripheral undermining, and circular keratectomy (group IV). Corneal topography was assessed weekly using keratometry and photokeratoscopy. All eyes showed central corneal steepening with enhancing effects of increased surgical manipulation. Results were stable by 4 weeks in all eyes. Histopathologic evaluation revealed a constant wound depth of approximately 0.1 mm, with an increased accumulation of glycosaminoglycan material at the base of the wound. This was stained with PAS and alcian blue. Steepening of the host cornea may be another reason for lack of predictability and refractive regression following epikeratoplasty.

Animals↗
PubMed1989

A new modified vitreoretinal surgical approach in the management of massive suprachoroidal hemorrhage.

The authors describe a new surgical approach used in six consecutive patients referred to us between August 1986 and August 1988 with massive suprachoroidal hemorrhage (MSCH) during or after cataract extraction (4 patients), glaucoma filtering surgery (1 patient), or scleral buckling (1 patient). All patients had large hemorrhagic choroidal detachments with five eyes showing "kissing" detachments. Secondary surgery was delayed 7 to 25 days (mean, 14 days) to allow liquefaction of the blood clot and reduce intraocular inflammation. All eyes underwent posterior drainage sclerotomies under constantly maintained limbal fluid infusion line pressure, followed by pars plana anterior and posterior vitrectomy in five of six eyes. Additionally, two eyes underwent secondary lens implantation during surgery and 6 months later, respectively. Mean follow-up was 10 months. Visual acuity improved in all eyes from a preoperative range of light perception-hand motions to hand motions-20/40. Advantages and disadvantages of this aggressive surgical approach in the management of MSCH are discussed.

Aged↗
PubMed1989

Survival of Streptococcus viridans in gentamicin-supplemented McCarey-Kaufman medium.

Our experience with three cases of Streptococcus viridans endophthalmitis, following penetrating keratoplasty, prompted us to investigate the ability of gentamicin-supplemented McCarey-Kaufman (M-K) medium to kill S. viridans contaminants. After inoculation of 20 cc of gentamicin-supplemented M-K with S. viridans, the M-K was exposed to temperature conditions similar to those that would be encountered by a donor cornea during storage (4 degrees C) and preoperative warming prior to keratoplasty (23 degrees C). Colony counts were performed at regular intervals. After 1 h of warming, no reduction in the initial inoculum had occurred. This is in contrast to results from similar experiments with Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa in which more than 1 log unit of killing occurred after 1 h. While previously reported clinical experience has demonstrated an overall low incidence of postkeratoplasty endophthalmitis using gentamicin-supplemented M-K, our own recent clinical and laboratory data suggest that additional or alternate antibiotic coverage for S. viridans may be prudent.

Cell Survival↗
PubMed1989

Corneal steepening after epikeratoplasty.

Four patients had removal of their epikeratoplasty lenticules for unsatisfactory visual results. This was out of a consecutive series of 36 eyes. Three eyes were myopic and one was aphakic. In all four eyes, there was significant corneal steepening with an average increase in myopia of 2.4 diopters and an average increase in keratometry reading of 4.8 diopters. Corneoscopy was done in three cases and showed central corneal steepening. In addition, one patient (Case 1) had significant scarring of the recipient cornea and a decrease in visual acuity to 20/100. The reasons for corneal steepening may be related to midperipheral partial trephination, annular keratectomy, and spreading of the peripheral cornea.

Adult↗
PubMed1988

Streptococcal endophthalmitis from contaminated donor corneas after keratoplasty. Clinical and laboratory investigations.

We report three cases of Streptococcus viridans endophthalmitis following penetrating keratoplasty in which S viridans was cultured from the recipient eye, McCarey-Kaufman (M-K) media, and corneoscleral rims. As a laboratory correlation, we investigated the ability of S viridans to survive in M-K medium supplemented with gentamicin. After M-K medium was inoculated with S viridans, it was stored overnight at 4 degrees C, after which the temperature was raised to 23 degrees C. Periodic colony counts were performed for up to 24 hours after warming. No killing occurred in the cold. Ten hours passed before there was one log reduction in the bacterial colony count. Organisms could still be cultured at 24 hours. We conclude that gentamicin alone may be inadequate prophlyaxis against S viridans contamination of donor corneas.

Cornea↗
PubMed1986

Is the corneal posterior cell layer truly endothelial?

The posterior cell layer of the normal human cornea or "endothelium" was investigated by electron microscopy and immunocytochemistry. Ultrastructurally, the cells lacked the characteristic marker for endothelial cells (Weibel-Palade body). Immunoperoxidase studies demonstrated these cells to be negative for factor VIII antigen, but strongly positive for keratine, vimentin, S-100 protein, and neuron-specific enolase. The anterior epithelial cell layer showed identical immunoreactivity. These studies strongly suggest that the posterior cell layer of the cornea lacks ultrastructural and immunocytochemical markers of endothelial cells and both the anterior and posterior cell layers share similar cell markers. The authors propose that the posterior cell layer of the cornea should, therefore, not be misnamed as "endothelium."

Cells↗