Faculty Bibliography

OBJECTIVE:To evaluate retroprosthetic membranes that can occur in 25% to 65% of patients with the Boston type 1 keratoprosthesis (KPro). METHODS:Two patients with Peter anomaly and 2 with neurotrophic scarred corneas underwent revisions of their type 1 KPros because of visually compromising retroprosthetic membranes. The excised membranes were studied by light microscopy with hematoxylin-eosin, periodic acid-Schiff, and toluidine blue stains. Immunohistochemical and transmission electron microscopic examination were also used. RESULTS:Light microscopic examination revealed that the retro-KPro fibrous membranes originated from the host's corneal stroma. These mildly to moderately vascularized membranes grew through gaps in the Descemet membrane to reach behind the KPro back plate and adhere to the anterior iris surface, which had undergone partial lysis. In 2 cases, the fibrous membranes merged at the pupil with matrical portions of metaplastic lens epithelium, forming a bilayered structure that crossed the optical axis. Retro-KPro membranes stained positively for α-smooth muscle actin but negatively for pancytokeratin. Electron microscopy confirmed the presence of actin filaments within myofibroblasts and small surviving clusters of metaplastic lens epithelial cells. CONCLUSIONS:Stromal downgrowth, rather than epithelial downgrowth, was the major element of the retro-KPro membranes in this series. Metaplastic lens epithelium also contributed to opacification of the visual axis. Florid membranous inflammation was not a prominent finding and thus probably not a requisite stimulus for membrane development. Further advances in prosthetic design and newer antifibroproliferative agents may reduce membrane formation.

BACKGROUND/PURPOSE/OBJECTIVE:To compare the rate of retroprosthetic membrane (RPM) formation in Boston Keratoprosthesis (BKPro) with polymethyl methacrylate (PMMA) versus titanium backplates. DESIGN/METHODS:Retrospective comparative chart review. METHODS:Multicenter study population: a total of 78 eyes with keratoprosthesis implants with either PMMA or titanium backplates were included in the study. To be included in the study, all subjects had to have completed a minimum of 6-month follow-up period. Incidence of RPM development at 6-month postoperative period was noted across the study population. PMMA and titanium backplates were then compared by their rate of association with subsequent RPM. RESULTS:Twenty-three out of 55 eyes (41.8%) with PMMA backplates and three out of 23 eyes (13.0%) with titanium backplates had developed an RPM at 6 months after implantation. The titanium backplates were associated with significantly less RPM formation than PMMA backplates (p = 0.014, Chi-square test). CONCLUSIONS:Titanium seems to be associated with less RPM formation than PMMA when used as a material for the BKPro back plate.

PURPOSE OF REVIEW/OBJECTIVE:To review emerging indications for the Boston keratoprosthesis (KPro) and to discuss current research underway to improve clinical outcomes. RECENT FINDINGS/RESULTS:In addition to multiple failed corneal grafts, other ocular conditions for which the Boston KPro has been used include herpetic keratitis, aniridia, autoimmune ocular disorders, and pediatric corneal opacities. In the recent years, the KPro has been implanted for various other conditions and has also been explored as a cost-effective treatment for severe corneal diseases internationally. Cicatricial and inflammatory ocular conditions remain the most difficult cases for KPro use but studies investigating various immunomodulators and biologic materials for improved retention are ongoing. Postoperative management of glaucoma is critical for preserving the visual gains achieved with the Boston KPro. Current studies are evaluating novel devices for intraocular pressure measurement. SUMMARY/CONCLUSIONS:Accrued experience with the Boston KPro has demonstrated its versatility but also the difficulties that remain in postoperative management. With many studies underway to improve cost-effectiveness, intra-operative and postoperative management, keratoprostheses will be made increasingly available to those countries most in need.

In this paper, we continue our evaluation of Forster-type theories of exciton diffusion in disordered environments. The perylenediimide dye Lumogen Red is used as a donor molecule in two different liquids, CHCl(3) and dimethylformamide, and the energy transfer to the acceptor molecule Rhodamine 700 is measured using time-resolved fluorescence decays. The exciton motion is measured over Lumogen Red concentrations ranging from 1 × 10(-4) to 5 × 10(-2) M, and the results are compared to previous results for exciton diffusion in a solid polymer. Depending on the theoretical approach used to analyze the data, we find that the energy migration in the liquids is a factor of 2-3 faster than in the solid polymer, even after taking molecular translation into account. Measurements for a Lumogen Red concentration of 10 mM in the different host environments yield diffusion constants ranging from 2.2 to 3.1 nm(2)/ns in the liquids, as compared to 1.1-1.2 nm(2)/ns in solid poly(methyl methacrylate) (PMMA). The results in the liquids are in good agreement with theoretical predictions and numerical simulations of previous workers, while the results in solid PMMA are 2-3 times slower. This discrepancy is discussed in the context of the rapid energetic averaging present in the liquid environments but absent in the solid matrix, where unfavorable configurations and low energy trapping sites are frozen in by the static disorder.

PURPOSE/OBJECTIVE:To report a case of corneal primary acquired melanosis (PAM) with atypia after cataract surgery. METHODS:Retrospective case report with literature review. RESULTS:Excision of an elevated pigmented conjunctival lesion was performed at the time of cataract extraction by clear corneal phacoemulsification by an outside surgeon. Histopathologic examination revealed PAM with atypia. Three months after the initial surgery, recurrent melanosis involving the peripheral corneal epithelium was noted, with extension of pigment into the corneal stroma through the paracentesis site. Excision of the involved corneal epithelium and the adjacent conjunctiva was performed, and microscopically recurrent PAM with atypia was confirmed. Adjuvant cryotherapy was applied at the time of surgery, and topical mitomycin C was given postoperatively. Repeat biopsies revealed no remaining malignancy, and the intrastromal pigment has disappeared during 18 months of follow-up. CONCLUSION/CONCLUSIONS:We present this case to illustrate the importance of complete evaluation and treatment of potentially atypical melanocytic conjunctival lesions before proceeding with elective intraocular surgery.

OBJECTIVE:To evaluate the role of immunohistochemical methods in the diagnosis of benign and malignant conjunctival melanocytic proliferations. DESIGN/METHODS:Retrospective immunohistopathologic study. METHODS:Paraffin-embedded tissue sections from 20 conjunctival nevi and 15 invasive melanomas were immunoreacted with antibodies against cellular antigens S-100 protein, MART-1, HMB-45, CD-45, and Ki-67 nuclear proliferation protein. RESULTS:All nevi immunostained moderately to strongly for S-100 protein and MART-1. Results for HMB-45 were negative in the middle and lower subepithelial portions of 18 of 20 lesions; it was usually only weakly positive within the superficial junctional zone. Only 1 melanoma did not stain positively for S-100; MART-1 and HMB-45 were positive in all lesions at some level of intensity. Ki-67 positivity was restricted to the junctional zone of nevi and was diffuse in melanomas. The mean Ki-67 proliferation indices were 1.89% for the nevi and 17.3% for the melanomas. CD-45 can help to highlight lymphocytes that immunostain with Ki-67. Melanomas in situ and atypical primary acquired melanoses had more than twice the Ki-67 proliferation counts of intraepithelial junctional nevocytes (P < .001) and more intense HMB-45 cytoplasmic staining than junctional zone nevocytes. CONCLUSIONS:S-100 and MART-1 were not useful in separating benign from malignant lesions. Results for nevus cells beneath the junctional zone were overwhelmingly negative for HMB-45 and Ki-67. Two nevi and all melanomatous nodules were positive for HMB-45 (P < .001). A higher Ki-67 proliferation index convincingly separated melanomas from nevi (P < .001). Immunostaining for HMB-45 and Ki-67 are valuable adjuncts to careful histopathologic evaluation in assessing benign and malignant conjunctival melanocytic tumors.

PURPOSE/OBJECTIVE:To describe a case of conjunctival malignant melanoma (MM) arising from primary acquired melanosis in a patient with neurofibromatosis type 1 (NF-1). METHODS:Case report and literature review. RESULTS:A 66-year-old woman with a history of NF-1 presented with extensive pigmentation of the left bulbar conjunctiva. Conjunctival biopsies demonstrated MM arising from primary acquired melanosis with atypia. Two excision and cryotherapy procedures did not completely eradicate the conjunctival pigment, which was then treated with topical mitomycin C. Subsequent biopsies and clinical examinations have revealed no remaining tumor. CONCLUSION/CONCLUSIONS:Conjunctival MM is uncommon in patients with NF-1 and can be successfully treated with excision, cryotherapy, and topical mitomycin C.