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Biomedical subjects

K Loftfield

Publications and source records attributed to K Loftfield.

13 recordsLinked to original sources

Filtering bleb encapsulation increased by steroid injection.

In an attempt to enhance its pressure-lowering and fibroblast inhibiting effects, we administered 0.15 cc of 24 mg/ml dexamethasone, intra-Tenon's, directly over the fistula site following 16 consecutive filtering surgeries. The encapsulation rate in these eyes was 56% (9/15), as compared with 10% (2/20) in a retrospectively matched group of eyes that had undergone filtering surgery with dexamethasone given subconjunctivally 180 degrees away from the filter site. The effective concentration of dexamethasone achieved by the injections at the filter site apparently did not maintain the fibroblast inhibitory drug level and, in fact, supported fibroblastic growth, resulting in increased encapsulation. Because of the increased encapsulation rate and the lack of any demonstrable benefit associated with it, we do not recommend intralesional dexamethasone in filtering surgery. Commercial topical steroids with their lower concentrations also may act to promote rather than inhibit fibroblast growth. Prolonged steroid use after filtering surgery beyond the inflammatory phase of wound healing (about 2 weeks) may increase fibrosis in the area of the filter, resulting in a thick-walled bleb with few microcysts, one form of which is frank encapsulation. Thus, we recommend that topical steroids routinely be stopped by the third postoperative week if the level of inflammation permits.

Adult↗

Molteno rip-cord suture hypopyon.

Seven of 27 eyes developed hypopyons following removal of a 4-0 chromic suture that had been placed intraoperatively in the lumen of the tube of a Molteno implant as a temporary occlusion device. The hypopyons were sterile to anterior chamber tap and in six of seven cases resolved with only routine antibiotic coverage. Surgeons contemplating using an internal chromic suture occlusion in Molteno implants, however, should be aware of this potential problem and adopt a conservative, noninvasive approach.

Adolescent↗

Orbital cyst formation associated with Gelfilm use.

Two patients developed cystic lesions in the anterior orbit 21 and 26 months after repair of blow-out fracture with orbital floor Gelfilm implants. Both patients had associated motility disturbances. Both lesions were surgically excised and found to be cystic in nature and filled with glistening gelatinous material consistent with partially absorbed, encysted gelatin film (Gelfilm). Histologically, a fibrous capsule was present; the contents of the cyst were not pathologically identifiable since they dissolved during fixation. Postoperatively, the motility disturbances improved in each patient.

Adult↗

A comparison of ciliary sulcus and capsular bag fixation of posterior chamber intraocular lenses.

We compare indications, advantages, and disadvantages of ciliary sulcus and lens capsular bag (lens capsular sac) fixation of posterior chamber intraocular lenses (IOLs). Our findings suggest that, whenever possible, it is efficacious to implant the loops of posterior chamber IOLs within the capsular bag. This positions the lens optic and the supporting loops in the natural anatomical position, sequestered from highly vascular uveal tissue and the blood aqueous barrier. This should minimize the potential for complications that may be associated with iris-ciliary body contact. Considering the rapid increase in the number of implantations of IOLs now being performed (approximately 700,000 per year in the United States alone), a possible reduction of even 1% in clinically significant complications would make this effort worthwhile. Widespread application of in-the-bag implantation is predicated on the assumption that the surgeon is proficient with this procedure and that careful follow-up of patients does not reveal any significantly increased incidence of lens dislocation due to zonular rupture.

Adult↗

Phthisis bulbi after intraocular lens implantation in a child.

A 4-year-old boy with trisomy 21 and a congenital cataract underwent cataract extraction and implantation of an iris-supported intraocular lens (IOL). Four years later the implant dislocated anteriorly and had to be removed. Now, 11 years postoperatively, the eye is blind, painful and shrunken. IOL implantation in infants and children is theoretically justified to preserve vision, reduce amblyopia and preserve fusion. The use of modern posterior chamber IOLs, especially when implanted in the lens capsular bag (if technically feasible), could reduce the risk of complications. However, until further data are accumulated, a conservative approach is warranted.

Blindness↗

Phacoanaphylactic endophthalmitis associated with extracapsular cataract extraction and posterior chamber intraocular lens.

We describe the clinicopathologic findings in a patient who underwent extracapsular cataract extraction (ECCE) with insertion of a posterior chamber intraocular lens (IOL). The patient had a sterile hypopyon and anterior uveitis that temporarily subsided but recurred. The inflammation actually worsened after removal of the IOL, and the eye was enucleated. Histopathologic examination showed a pattern consistent with phacoanaphylactic endophthalmitis. We therefore postulate that the patient's complications were due to hypersensitivity to her own lens protein, which remained after the ECCE, rather than to the IOL itself.

Aged↗

Biocompatibility of implant materials: a review and scanning electron microscopic study.

The evolution of various plastic materials used in the manufacture of intraocular lenses is reviewed, with special reference to the problem of biocompatibility of lens haptic materials. To date, polypropylene has been found and continues to be a highly effective, relatively inert material, providing good surgical results. However, the present study and other morphologic and chemical studies have provided evidence that indicates long-term alteration of polypropylene may occur. For this reason we believe that further studies of this particular polymer are warranted. Also, a continuing search and trial of other plastics to discover an equivalent or even more efficacious haptic material seems desirable. There is a need for careful long-term follow-up of patients after intraocular lens implantation, particularly of young patients.

Biocompatible Materials↗

Anterior segment complications and neovascular glaucoma following implantation of a posterior chamber intraocular lens.

Lens implantation is now a highly successful operation. Although follow-up over 5 to 10 years with posterior chamber lenses is incomplete, the complication rate appears to be as low or lower than other lens styles. We present an exception: a clinicopathologic analysis of a globe, enucleated 4 years postoperatively, which in spite of uneventful implantation of a posterior chamber lens, developed neovascular glaucoma. Microscopic studies suggest several mechanisms for this rare complication including deep erosion of a prolene loop into the ciliary body, anterior segment ischemia, and breakdown of the blood-aqueous barrier. Scanning microscopy showed cracking of this deeply embedded loop, a finding we interpret as possible stress cracking and/or oxidation. The more flexible loops now used in modern lenses may decrease the chance of deep erosion. Implantation of a loop in the capsular bag may minimize the danger of both erosion and loop degradation. Patients should be followed long-term in order to recognize and treat these rare, but potentially disastrous complications.

Anterior Chamber↗

Complications of intraocular lenses. A historical and histopathological review.

Recent improvements in intraocular lens (IOL) design, manufacturing techniques, and surgical techniques have greatly reduced the incidence of complications following implantation, and many authors now consider IOL implantation to be among the most safe and effective major surgical procedures. However, adverse reactions are still seen--some as late sequelae of earlier IOL designs and implantation techniques and some as sequelae of more recent implantations using "state-of-the-art" lenses and surgical techniques. Complications may be due to various factors, including surgical technique, IOL design, or the inability of some eyes with preexisting disease to tolerate an implant. The authors trace the evolution of IOLs since Ridley's first implant, summarizing the modifications in lenses and surgical techniques that were made as complications were recognized. They then review the clinical and histopathological features of selected cases from more than 200 IOLs and/or globes removed due to IOL-related complications and studied in the University of Utah Ocular Pathology Laboratory. It is hoped that this review will provide insights into the pathogenesis of IOL complications, enhancing the current success of implant procedures and stimulating further basic and clinical research in this area.

Anaphylaxis↗

Melanocytoma: nomenclature, pathogenesis, natural history and treatment.

A melanocytoma (magnocellular nevus) is a benign pigmented tumor that may arise wherever uveal melanocytes are present. The most commonly observed site is on or adjacent to the optic nerve head. In the past this tumor was frequently misdiagnosed as a malignant melanoma and many unnecessary enucleations were carried out. Its clinical features are now well recognized and, fortunately, specimens of melanocytomas are rarely received in ocular pathology laboratories today. A review of the literature concerning this tumor is presented, with special reference to the changing concepts in nomenclature, pathogenesis, natural history, and treatment that have evolved in the past one hundred years. We also define the clinical and histopathological features of this tumor.

Cell Transformation, Neoplastic↗

Ocular perforation and phthisis bulbi secondary to strabismus surgery.

We present our ocular clinicopathologic findings of a child who suffered bilateral perforation of the globe during medial rectus recession bilaterally for congenital esotropia. The right eye progressed to a painful phthisis bulbi and subsequently required enucleation. Penetration or perforation of the sclera during extraocular muscle surgery is not rare; however, serious sequelae such as visual loss or loss of the eye are unusual. Such complications can be avoided if the surgeon is aware of the causes, as well as the dangers, of such perforation, and, in particular, if modern spatula-type needles are used.

Child, Preschool↗