Faculty Bibliography

Four Arenberg endolymphatic shunts that had been implanted in patients for 6 years, 3 years, 24 months, and 11 months were removed during retrolabyrinthine nerve sections (two cases), labyrinthectomy (one case), or cochlear implant (one case). The shunts were examined and photographed grossly and the components were prepared for light and scanning electron microscopy. Acellular debris filled the vestibule around the valve in all cases. The same material filled the inside of the valve in two cases and could be seen coming through the valve in two cases. Two shunts had ingrowth of fibrous tissue into the sponge. The finding of greatest concern was multiple erosions seen in the Supramid tube (S. Jackson Inc, Alexandria, Va) that inserts into the endolymphatic sac. On scanning electron microscopy, these erosions appeared as a network of cracks in the outer surface of the tube. The two shunts implanted for the longest time had fenestrae completely through the tube wall. These findings question the long-term functioning and integrity of the Arenberg shunt

In a five-year review, we identified 29 cases of microbial infection in 28 patients who were 16 years old or younger. Herpes simplex infections were excluded. Predisposing factors included trauma (ten cases, 34%), severe systemic illness (eight cases, 27%), contact lens use (seven cases, 24%), exposure keratopathy (seven cases, 24%), and previous ocular surgery (six cases, 21%). A total of 24 microorganisms were identified in cultures of corneal scrapings from 22 of the 29 cases; two cases involved polymicrobial infections. Of the 24 identified pathogens, gram-positive cocci were the most common (12). Other microorganisms included gram-negative bacteria (five) and fungi (four). Isolated cases of Acanthamoeba species, Borrelia burgdorferi, and Bacillus species were also present. Therapy with intensive topical antibiotics was successful in this series. The rate of surgical intervention (6/29, 21%) was similar to that of previous reports

Ten corneal specimens obtained at the time of penetrating keratoplasty for long-standing refractory Acanthamoeba keratitis were reviewed. Histopathologic findings included epithelial denudation and variable degrees of necrosis, inflammation, and cysts or trophozoites of acanthamoeba in the stroma. No blood vessels were found in the stroma despite the presence of long-standing corneal inflammation. The absence of corneal stromal neovascularization on biomicroscopic and histopathologic examination is a sign of Acanthamoeba keratitis

In a prospective study 155 consecutive patients undergoing penetrating keratoplasty were examined for postoperative increase in intraocular pressure to determine the frequency and duration of intraocular pressure spikes, risk factors, and response to treatment. Patients were maintained on preoperative glaucoma medications except miotics. Additional medications to lower intraocular pressure perioperatively were not given. Intraocular pressure was measured two to five hours, one day, and one week postoperatively. An intraocular pressure of 30 mm Hg or greater was considered an increase in pressure and was treated according to a standardized protocol. The results were analyzed by procedure as well as by variables commonly perceived to be associated with intraocular pressure increase (history of glaucoma, use of hyaluronate, lysis of the synechiae, or vitrectomy at the time of the operation). Overall, intraocular pressure increases in the early postoperative period occurred in 18 of 155 patients (12%). Pressure increases occurred in ten of 48 patients (21%) with a history of glaucoma; five of 24 patients (21%) undergoing combined penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber intraocular lens implantation; and ten of 43 patients (23%) undergoing vitrectomy at the time of penetrating keratoplasty

Histopathologic slides from 170 failed grafts, excised between 1983 and 1990 were reviewed. The overall incidence of retrocorneal fibrous membrane was 54% (92 grafts). The incidence of diffuse (extensive) retrocorneal fibrous membrane was 17% (29 grafts) and that of focal (peripheral) retrocorneal fibrous membrane was 37% (63 grafts). A high correlation was found between the clinical presence of peripheral anterior synechiae or vitreous adherent to the wound and the finding of retrocorneal fibrous membrane in aphakic and pseudophakic failed corneal grafts. A high correlation was also found between tube-shunt operation and the presence of diffuse retrocorneal fibrous membrane. Sixteen of 63 (25%) regrafted failed grafts, that is second grafts, with focal retrocorneal fibrous membranes failed within 18 months following surgery. Thirteen of 29 (45%) regrafted failed grafts with diffuse retrocorneal fibrous membrane failed within the same period and 11 of these (85%) were associated with tube-shunt surgery

Eight aniridic patients with bilateral corneal scarring, vascularization, or edema underwent corneal transplantation in one or both eyes (11 eyes). Follow-up ranged from eight months to 5 1/2 years (average, three years). Six of 11 eyes (55%) had at least a two-line improvement in visual acuity and eight of 11 (73%) had at least one line of improvement. Best-corrected visual acuity was 20/200 or worse in nine of 11 eyes (82%), however. Postoperative complications included whorl keratopathy, persistent epithelial defects, central subepithelial scarring, peripheral vascularization with pannus, and graft rejection. Glaucoma was well controlled medically but five of nine patients (56%) with preexisting glaucoma needed an increase in medication for intraocular pressure control. Graft rejection occurred in seven of 11 eyes (64%) and three of these eyes required repeat transplantation