J. Douglas Cameron

Polysulfone corneal lenses.

ABSTRACT Polysulfone is a thermoplastic compound first synthesized in 1965. A unique characteristic of polysulfone is its high refractive index (1.633), which allows very thin optical lenses to be manufactured. Over the last five years, D. Peter Choyce has surgically implanted over 40 polysulfone lenses into eyes of his patients. Analysis of his data indicates that polysulfone intraocular lenses are capable of correcting large refractive errors. Based on his work, a multicenter study was undertaken to evaluate the safety and efficacy of polysulfone as an intracorneal lens material in laboratory models. Four monkeys, eight baboons, and 24 cats were used as laboratory models; 5.0‐mm to 6.0‐mm diameter hyperopic (+28.5 diopter) and myopic (‐17.0 and ‐25.5 diopter) lenses were surgically implanted within the corneal stroma in one eye of each of the laboratory models while a sham lamellar dissection was performed in the other eye. One hundred percent (4/4) of monkey eyes, 12.5% (1/8) of baboon eyes, and 70.0% (18/24) of cat eyes maintained clear media by ophthalmoscopic examination at follow‐ups ranging from three to six months. Complications included both visually and nonvisually significant interface opacities, lens extrusion, anterior corneal necrosis, refractile particles, and epithelial thinning.

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 Descemets 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.

Silver Modification of Polyethylene Terephthalate Textiles for Antimicrobial Protection

The safety and in vitro effectiveness of applying silver to polyethylene terephthalate fabric mechanical heart valve (MHV) sewing cuffs for the prevention of prosthetic valve endocarditis (PVE) were evaluated. PVE is an infrequent but grave complication of cardiac surgery associated with mortality rates potentially exceeding 50%. A poor response to antibiotic therapy is partly responsible for the high mortality rates. Silver is a well known antimicrobial agent with broad effectiveness. Preliminary in vitro microbial challenge studies of the coated fabric using the New York State 63 bacteriostatic test and Dow Corning Shake Flask test showed a s>97% reduction for most organisms tested. Sheep mitral valve replacement studies suggest

An experimental model for uveal touch syndrome.

ABSTRACT Posterior chamber intraocular lenses (IOLs) were implanted in cat eyes after extracapsular cataract extraction or phacoemulsification. Various degrees of iris and IOL contact occurred. In 52% of the eyes in which contact was present, there was associated fibrovascular membrane formation, which was statistically significant when compared to eyes in which there was no iris‐IOL contact. The eyes were examined histopathologically; proliferation of anterior cuboidal cells, as well as a fibrous response within the stroma, was noted in eyes with the most extensive contact. Human clinical correlates are discussed. This study demonstrates experimentally that the iris will not tolerate significant prolonged IOL contact.

Unsuspected infectious keratitis in host corneal buttons

Infectious keratitis may be unsuspected preoperatively in patients undergoing penetrating keratoplasty. We have diagnosed five cases of previously unknown corneal infection discovered only after post-keratoplasty histopathologic examination using specific stains. These cases of preoperatively unsuspected infectious keratitis illustrate examples where histopathologic examination using specialized stains may alert the physician to the need for appropriate postoperative antimicrobial therapy. Furthermore, these cases illustrate the ability of soft contact lenses to mask symptoms of infectious keratitis. Additionally, the clinical appearance of advanced bullous keratopathy may mask signs of infectious keratitis.

Circumferential nodulocystic keratopathy

An apparently unique type of corneal nodular keratopathy is presented. The keratopathy was characterized by large, circumferentially bilaterally located, cystic nodules just inside the limbus. No epithelial cell or collagenous degeneration nor evidence of chronic inflammatory process was found on histopathologic examination of a biopsy of a nodule. Proteinaceous material was present between the epithelial cell basement membrane and collagenous stroma. There was no antecedent history of keratitis or uveitis. The patient was known to have inflammatory bowel disease (regional ileitis) and rheumatoid arthritis with ankylosing spondylitis. However, the corneal lesions could not definitely be associated with any of these disorders. This case does not correspond with any previously described corneal disorders. We have termed it circumferential nodulocystic keratopathy, which best describes its clinical and histologic features.An apparently unique type of corneal nodular keratopathy is presented. The keratopathy was characterized by large, circumferentially bilaterally located, cystic nodules just inside the limbus. No epithelial cell or collagenous degeneration nor evidence of chronic inflammatory process was found on histopathologic examination of a biopsy of a nodule. Proteinaceous material was present between the epithelial cell basement membrane and collagenous stroma. There was no antecedent history of keratitis or uveitis. The patient was known to have inflammatory bowel disease (regional ileitis) and rheumatoid arthritis with ankylosing spondylitis. However, the corneal lesions could not definitely be associated with any of these disorders. This case does not correspond with any previously described corneal disorders. We have termed it circumferential nodulocystic keratopathy, which best describes its clinical and histologic features.

The Crystalline Lens

The human crystalline lens is the second most important refracting element of the eye. The lens functions primarily in accommodative vision. The lens doubles in volume between birth and age 70. Approximately at age 40, the lens loses its ability to accommodate because of loss of pliability, and at age 70 the transparency of the lens is reduced resulting in cataract formation.

Neonatal asteroid hyalosis

Asteroid hyalosis, noted in 0.83% of routine eye examinations, is uncommon in younger patients and is more frequently seen in patients more than 60 years old. It has been considered to be related to an aging process, and when it occurs in younger patients, ocular disease is typically associated. We report a 4-week-old patient with Down syndrome and bilateral congenital cataracts who had unilateral asteroid hyalosis.