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Biomedical subjects

J I McNeill

Publications and source records attributed to J I McNeill.

At least 19 recordsLinked to original sources
PubMed2001

Flared phacoemulsification tips to decrease ultrasound time and energy in cataract surgery.

PURPOSE: To determine the effect on ultrasound (US) time and energy of using flared phacoemulsification tips in cataract surgery. SETTING: Private referral practice of Pacific Cataract & Laser Institute, Chehalis, Washington, USA. METHODS: One surgeon using the Allergan Medical Optics Diplomate phacoemulsification machine performed cataract surgery by a single divide-and-conquer technique. A prospective nonmasked consecutive study group (n = 262) was selected from patients operated on with phaco tips flared by 25%. A consecutive control group (n = 440) was selected from patients having surgery using the same technique except for the use of straight phaco tips. The study group had cataract surgery over a 5 week period and the control group, over an earlier 10 week period. Two weeks separated the groups. Cases complicated by vitreous loss were eliminated. The 2 groups were compared by age, sex, total phaco time (TPT, the total time ultrasound energy was applied), and equivalent phaco time (EPT, the product of the phaco time elapsed and the phaco energy). RESULTS: One patient in each group was eliminated for vitreous loss during surgery. There were no significant differences in age, sex, or eye between the 2 groups. The study group had a mean TPT of 29.2 seconds +/- 11.7 (SD) (range 0 to 88 seconds) and a mean EPT of 16.4 +/- 8.6 seconds (range 0 to 67 seconds). The control group had a mean TPT of 34.4 +/- 16.1 seconds (range 0 to 130 seconds) (P <.001) and a mean EPT of 20.0 +/- 12.8 seconds (range 0 to 107 seconds) (P <.001). CONCLUSION: Flared ultrasonic phacoemulsification tips significantly reduced the US time and energy used in cataract surgery.

Adult↗
PubMed1999

Long-term results of single continuous suture adjustment to reduce penetrating keratoplasty astigmatism.

PURPOSE: To evaluate the long-term effect of single continuous corneal suture adjustment on reducing penetrating keratoplasty astigmatism after suture removal. METHODS: Patients were identified from the original study of single continuous penetrating keratoplasty suture adjustment to reduce corneal astigmatism who were followed for more than a year after suture removal. A matching unadjusted control group was selected in the same way from those patients in the original study undergoing penetrating keratoplasty during the 2 years before the development of suture adjustment. The corneal astigmatism was compared before adjustment (study group) or <3 months after surgery (control group), >4 months after suture adjustment, and >12 months after suture removal in both groups. RESULTS: A study group of 54 patients with suture adjustment and a control group of 45 patients without suture adjustment were identified. Before suture adjustment, the study group had an average keratometric astigmatism of 6.44 diopters (standard deviation [SD] = 2.51, range = 0.38-12.25), and the control group had 6.38 diopters (SD = 3.29, range = 2.75-16.00, p = 0.536). Compared to that in the unadjusted control group, the average penetrating keratoplasty astigmatism in the suture-adjusted group was reduced by 44.6% (2.36 diopters) 4.5 months after surgery and before suture removal (p = 0.0002) and by 25.4% (1.19 diopters) at least 12 months after suture removal (p = 0.011). CONCLUSION: Postoperative adjustment of a single continuous corneal suture significantly reduces penetrating keratoplasty astigmatism after suture removal.

Adolescent↗
PubMed1995

Herpes simplex virus DNA in normal corneas: persistence without viral shedding from ganglia.

Herpes simplex virus type 1 (HSV-1) DNA has been shown to persist in the cornea not only after inoculation of experimental animals but also in surgical samples from patients with herpes keratitis. The further observation of corneal HSV-1 DNA in subjects without known HSV eye disease prompted the present study of the presence and distribution of HSV-1 in eye bank corneas. Prior to DNA extraction, the corneas were trephined, separating the central and peripheral cornea. With polymerase chain reaction (PCR) for HSV-1 thymidine kinase (TK) and glycoprotein D (gD) gene sequences, we found HSV-1 in 10 of 24 eye bank corneas, from the 4 mm wide corneal rim in 8 eyes and from the 8 mm diameter central cornea in 2 eyes. In 9 subjects, both eyes were assayed, and HSV-1 was detected in 6 subjects. In only one subject was HSV-1 detected in both eyes and in only one subject was HSV-1 detected in the central and peripheral cornea of the same eye. The biological role of HSV-1 DNA corneal sequences is unknown. To investigate this, a rabbit animal model was established by transplantation of corneas containing viral DNA sequences in HSV-1 naive recipients. Followed for 5 months, there was no evidence of sheeding of HSV-1 in the tear film or seroconversion of the recipient rabbits. At the end of this time, HSV-1 DNA was detected in the corneal graft at a similar intensity to the PCR signal from the donor rims.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Corneal incision dehiscence during penetrating keratoplasty nine years after radial keratotomy.

As the use of radial keratotomy (RK) to correct myopia increases, more patients are having penetrating keratoplasty (PK). Radial keratotomy incisions are known to show incomplete wound healing. When the radial corneal RK incisions are cut by the corneal trephine, the peripheral part of each incision may open, even years after surgery. In this case, a 56-year-old man had visual distortion and diplopia in one eye nine years after RK. Contact lenses did not correct the problem, and the patient could not tolerate the contact lenses. Penetrating keratoplasty was performed. During surgery about one-third of the peripheral RK incisions spontaneously opened, making suturing difficult. Although the final visual result was 20/20 corrected acuity, this case shows that RK incisions may remain incompletely healed and easily open during PK surgery as long as nine years after the RK surgery.

Cornea↗
PubMed1991

An improved palpebral spring for the management of paralytic lagophthalmos.

Facial nerve paralysis with orbicularis muscle palsy can result in serious corneal complications, such as exposure, ulceration, and perforation. Eyelid springs have been used for patients with orbicularis muscle palsy to provide corneal protection while maintaining vision by restoring some kinetic eyelid function. The authors report on 24 patients with facial nerve paralysis who underwent implantation of an eyelid spring over a period of 8 years. The most common cause of orbicularis muscle paralysis was acoustic neuroma, followed by squamous cell carcinoma. Eighty-three percent of the cases successfully regained and maintained their eyelid function during the follow-up period, averaging 3.0 years. We have modified the spring to allow permanent attachment to the orbital rim by wiring. This modification of the surgical technique has minimized the most common postoperative complication: loosening of the spring from its periosteal attachment with subsequent loss of function and extrusion. In addition, transcutaneous adjustments of the spring now can be made without an incision using clasp-adjusting dental pliers. In selected patients, the placement of an eyelid spring prevents the corneal complications associated with paralytic lagophthalmos while maintaining visual function.

Adolescent↗
PubMed1990

Posterior infectious crystalline keratopathy with Staphylococcus epidermidis.

Two cases of infectious crystalline keratopathy located in the posterior stroma after penetrating keratoplasty are presented. Topical steroids and suture removal were risk factors in both cases. In the first case, a moderate anterior chamber reaction was present. Crystalline infiltrates persisted on topical and systemic steroid therapy. In the second case, deep corneal ulceration, hypopyon, and vitreitis were noted. A vitreous aspirate showed rare gram-positive cocci in pairs. The corneal ulceration and crystalline keratopathy persisted despite intravitreal and topical antibiotics. Therapeutic penetrating keratoplasty was performed in both cases. Staphylococcus epidermidis sensitive to vancomycin was isolated from corneal tissue. Light microscopy documented aggregates of gram-positive bacteria anterior to Descemet's membrane, with an overlying keratitis. Electron microscopy in the second case showed all bacteria within stromal keratocytes. No clinical recurrence was seen using topical vancomycin. As demonstrated in the cases presented, infectious crystalline keratopathy can occur exclusively in the deeper layers of the cornea. Isolation of S. epidermidis, associated inflammation, and intraocular spread of organisms are rare findings.

Aged↗
PubMed1990

An adjustable single running suture technique to reduce postkeratoplasty astigmatism. A preliminary report.

The authors compared postkeratoplasty astigmatism over a 4-month period after surgery in a randomized, prospective study of two groups of patients (total N = 18) who received two different suture techniques. The test group N = 8) had a single running suture with postoperative suture adjustment; on the basis of computer-assisted topographic analysis, the suture was tightened in the flatter meridian and loosened in the steeper meridian in the first month after surgery. The control group (N = 10) had a standard double running suture procedure with no postoperative adjustment; the single running 10-0 nylon suture was removed 3 months after surgery. Four months after penetrating keratoplasty, mean (+/- standard deviation) astigmatism in the test group was 1.7 +/- 0.7 diopters (D), and all patients had less than 2.6 D of astigmatism. In the control group, mean astigmatism was significantly higher (5.4 +/- 2.4 D; range, 0.7-9.0 D; P less than 0.01). The results suggest that postkeratoplasty astigmatism can be reduced with the single running suture technique accompanied by postoperative suture adjustment.

Astigmatism↗
PubMed1989

Applicator for cyanoacrylate tissue adhesive.

Cyanoacrylate tissue adhesive (CTA) is very useful for emergency treatment of corneal perforations. Lack of Food and Drug Administration approval as well as concerns about toxicity from the application of large amounts of glue, however, have limited its use. It is difficult to apply a sufficiently small amount of glue or to achieve a water tight seal using published techniques of glue application. We have found a commercially available micropipette (used in dental work) to be more effective than other methods of CTA application. With this apparatus, precise and accurate placement of minimal amounts of CTA at the slit lamp is consistently possible.

Adult↗
PubMed1979

Local antivirals in a herpes simplex stromal keratitis model.

A herpes simplex stromal keratitis rabbit model, which was produced by intrastromal injection of live virus, was used to evaluate the effects of local antivirals on the natural course of the disease. Topical trifluridine (trifluorothymidine) and vidarabine monophosphate (adenine arabinoside monophosphate), when given early and frequently, suppressed the disease, indicating that viral replication was important in initiating the disease. However, seven days after the stromal disease had begun to develop, neither drug had an appreciable effect. Since the early drug effect had suggested adequate drug penetration, the abscence of drug effect later in the disease indicates that viral multiplication may not be important in maintaining the disease. Immunologic reactions may control the disease once the cornea is antigenically altered by the initial infection. Subconjunctivally injected trifluridine was not effective.

Animals↗
PubMed1978

Leukocyte migration inhibitory factor in HSV infections.

The cell-mediated immune (CMI) response as measured by a direct assay of leukocyte migration inhibition factor (LMIF) was determined in a population of patients with recurrent herpes simplex virus (HSV) infections in the quiescent stage as well as in healthy volunteers. The migration of leukocytes incubated in the presence of HSV antigens was compared to that without viral antigens for the calculation of the migration index (MI). Eleven of 41 control subjects (16.8%) had a MI below 0.8, indicating a positive CMI response. In contrast, all the herpes patients tested had a MI above 0.8, suggesting an impairment in the production of LMIF at this stage of their disease. This difference was statistically significant (t = 4.296; p less than 0.001) and was not dependent on the age of the population. This study indicates that individuals with recurrent HSV infections have impaired CMI response betweeen attacks which may be associated with the stage of the disease.

Adolescent↗
PubMed1977

Combined scleral ring and blepharostat.

A modified Legrand scleral ring served three important functions: it prevented anterior scleral buckling and collapse, it separated the eyelids to give good surgical field exposure, and it provided firm fixation for the globe during trephining and suturing.

Corneal Transplantation↗