Histopathology of explanted collar button keratoprostheses: a clinicopathologic correlation.

PURPOSE: To compare the histopathology of three PMMA collar button type keratoprosthesis (KPro)/corneal specimens, explanted due to various complications, with that from one KPro/corneal specimen taken postmortem from an otherwise "healthy" enucleated eye. METHODS: Patient 1 (chemical injury) had no problems for 3 years after KPro placement; the entire eye was obtained postmortem. Patient 2 (repeated graft failures, nonautoimmune disease) developed an "unlaserable" retroprosthesis membrane 4 months after KPro placement. A new KPro was placed. Patient 3 [ocular cicatricial pemphigoid (OCP)] developed tissue melt at the KPro-cornea interface 7 months after KPro placement, and the KPro was replaced. Patient 4 (OCP) developed progressive corneal melt around the KPro 3.5 years after placement resulting in replacement. All KPro/cornea specimens were processed and sectioned for histology with the KPro in place. RESULTS: All patients exhibited growth of corneal or conjunctival derived epithelium under the KPro front plate. In patients 1 and 2, no epithelial downgrowth was noted and the keratocyte density appeared normal with few inflammatory cells present. Dense fibrous tissue was present behind the KPro in patient 2. Patients 3 and 4 showed massive inflammatory cell infiltration and tissue necrosis with "melt" adjacent to the stem resulting in epithelial downgrowth. CONCLUSIONS: Corneal inflammation and degradation after KPro placement correlate well with the preoperative diagnostic category. Patients with immune-related corneal surface disease can exhibit marked inflammatory responses leading to necrosis, stromal melting, and the formation of an epithelial fistula. In contrast, patients without autoimmune corneal disease demonstrate a remarkably noninflamed cornea with intact keratocytes and without epithelial ingrowth, commensurate with their clinical appearance.

Performance characteristics of digital fundus photography as a screening test for diabetic retinopathy in a low-risk population.

The purpose of the present study was to estimate the sensitivity and specificity of reviewers' assessments of digital fundus photography (DFP) images, using the findings from comprehensive ophthalmologic examination as the criterion standard. One hundred and fifty-two patients with diabetes underwent comprehensive ophthalmologic examination by an active duty U.S. Air Force (ADAF) staff ophthalmologist, and the examination findings were used as the criterion standard for the present study. Eight other ophthalmologists (M.D.'s) and 10 optometrists (O.D.'s), all ADAF providers, each evaluated seven nonstereo standard field DFP images from the left and right eyes (14 images per patient) of the 152 diabetic patients, assessing each patient for evidence of diabetic retinopathy (yes, no, not sure). The sensitivity, specificity, and proportion of "not sure" responses were computed separately for MD and OD reviewers and then compared. O.D. reviewers gave "not sure" responses more frequently than M.D.'s. With "not sure" responses treated as correct (i.e., identical to the results of ophthalmologic examination), both types of providers had 100% sensitivity for cases that are usually treated and 83% sensitivity for cases that are not usually treated but require close follow-up. Specificity (for any diabetic retinopathy) was 92% for M.D.'s and 93% for O.D.'s. With M.D.'s as photographic reviewers, DFP-based screening required only 27 ophthalmologic examinations per 100 patients screened; with O.D.'s as photographic reviewers, 31 ophthalmologic examinations were required per 100 patients screened. Using either ophthalmologists or optometrists as photographic reviewers, DFP-based screening for diabetic retinopathy has very good sensitivity and excellent specificity.

Keratoprosthesis: an update.

Porous polytetrafluoroethylene and polyurethane skirt materials, as well as copolymers of poly (2-hydroxyethyl methacrylate), have shown promise in approaching the goal of a "biointegratable" keratoprosthesis. A novel fixation method that uses scleral haptics also has been introduced to increase stability. An all silicone device that can be sewn into position has been used successfully, temporarily, during vitreoretinal procedures. The prognosis of keratoprosthesis (KPro) procedures depends on the preoperative diagnosis: graft failure-noncicatrizing disease>ocular cicatricial pemphigoid>chemical burns>Stevens-Johnson syndrome. The likelihood of endophthalmitis after KPro surgery follows this scheme. Causative organisms tend to be gram-positive. Modified vitreoretinal techniques also have been developed, allowing successful treatment of posterior segment complications. The science of keratoprosthesis is advancing more rapidly than in previous years. However, use of KPro to address complicated corneal blindness worldwide remains limited. The authors conducted an English language literature review from January 1, 2000 to April 1, 2001 and describe advances of note in the field of keratoprosthesis design, materials, and medical and surgical management.

Scalp necrosis with giant cell arteritis.

OBJECTIVE: Giant cell arteritis (GCA) often presents with devastating visual loss in the elderly, yet early diagnosis and treatment can prevent visual loss. The authors report two cases of GCA in which scalp necrosis, a rare finding not reported previously in the ophthalmic literature, played an important role in diagnosis. DESIGN: Observational case reports and literature review. PARTICIPANTS: Two patients with GCA had scalp necrosis. INTERVENTION: Intravenous steroid administration was performed. MAIN OUTCOME MEASURE: Vision and healing of scalp necrosis were measured. RESULTS: One patient had scalp necrosis that was diagnosed incorrectly preceding visual loss. Another patient had visual loss in one eye diagnosed as nonarteritic anterior ischemic optic neuropathy. He had scalp necrosis develop 2 weeks later, leading to the correct diagnosis of GCA. There are 21 previously reported cases of scalp necrosis with GCA, none in the ophthalmic literature, most of which were undiagnosed until the onset of visual loss. In addition, a higher rate of visual loss is seen in GCA with scalp necrosis. CONCLUSIONS: Scalp necrosis is a valuable sign that frequently is misdiagnosed until visual loss occurs. In addition, it may indicate a more severe vasculitis. This finding should be added to the list of signs evaluated in patients for whom GCA is in the differential diagnosis.