Clinicopathologic findings in eyes with retained perfluoro-n-octane liquid.

OBJECTIVE: To describe the clinical and histopathologic findings in five eyes with retained perfluoro-n-octane (PFO) liquid after retinal reattachment surgery. DESIGN: Retrospective, noncomparative, clinicopathologic case series. PARTICIPANTS: Surgical specimens from five eyes were studied. METHODS: Surgical specimens from eyes with prior intraoperative PFO use submitted to the W. Richard Green Eye Pathology Laboratory at the Wilmer Ophthalmological Institute were identified and reviewed. MAIN OUTCOME MEASURES: Histopathologic analysis and energy dispersive spectroscopy identified intracellular vacuoles containing PFO. RESULTS: Five cases were identified. Three specimens were obtained at the time of further surgery for recurrent retinal detachment; one at repeat penetrating keratoplasty, and one at removal of retained PFO. Each eye had macroscopic white flake-like material on intraocular structures noted before or during surgery. Histopathologic analysis disclosed an inflammatory response featuring macrophages with intracellular vacuoles containing PFO. Removal of the PFO in all five eyes combined with repeat retinal reattachment surgery in three eyes resulted in resolution of the inflammatory response. CONCLUSIONS: Retention of PFO after surgery elicits an inflammatory response. We suspect that young patients, those with considerable residual vitreous gel, and eyes with larger amounts of retained PFO may be at higher risk for this complication.

Velocity measurements of normal and sickle red blood cells in the rat retinal and choroidal vasculatures.

The purpose of this study was to develop an in vivo, noninvasive method to assess the velocities of normal and sickle red blood cells (RBCs) in the retinal and choroidal vasculatures of rats. Human and rat RBCs were isolated from whole blood, labeled with fluorescein isothiocyanate (FITC), and administered intravenously to anesthetized rats. A Rodenstock scanning laser ophthalmoscope (SLO) was used to image the FITC-labeled RBCs as an NTSC video signal. Video sequences of RBC transit in the retinal (pigmented rats) and choroidal (albino rats) vessels were captured directly to digital format. Following in vivo angiography, the animals were sacrificed, the eyes enucleated, and retinas prepared by our adenosine diphosphatase vascular labeling technique for viewing by conventional optical microscopy. Although rat and normal human RBCs differ slightly in size, their velocities were similar in the retinal arteries and capillaries (within 4%). Velocities of RBCs from sickle cell patients (sRBCs) were slower by 12 and 9% in arteries and by 38 and 25% in capillaries, compared to rat and normal human RBCs, respectively. Compared to velocities in retinal capillaries, the velocities in choroidal capillaries were much slower for rat RBCs (77%), normal human RBCs (79%), and sRBCs (67%). In contrast to normal human RBCs, sRBCs were often retained transiently in retinal capillaries at preferred sites, but in choroidal capillaries large numbers of cells were retained for extended periods. SLO imaging of FITC-labeled RBCs in rat retina and choroid provided a reliable method for evaluating normal and abnormal hemodynamics.

Visualization of a developing vasculature.

The events involved in vasculogenesis still remain obscure. One difficulty has been the techniques employed to visualize angioblasts, i.e., vascular precursors, during the genesis of blood vessels. The retina provides a unique model for studying these events since it is not completely vascularized in some mammals at birth. Using a previously published magnesium-dependent ATPase technique to visualize the developing retinal vasculature and its precursors, and embedding this tissue in JB-4 methacrylate for serial sectioning, has permitted examination of the retinal vasculogenic processes in dual perspective. The technique has permitted observation of the stages in angioblast differentiation and the apparent importance of glycosaminoglycan-rich cell-free spaces in this process. Perhaps the most important observation is that initial vessel formation occurs by coalescence of angioblasts after differentiation in situ.

Postnatal retinal vascular development of the puppy.

Retinal vascular development during the first three postnatal weeks was studied in 63 purebred beagle puppies. Use of a positive enzyme histochemical reaction for adenosine triphosphatase in the nuclei and nucleoli of vascular cells made visualization of the retinal vasculature possible. Animals were killed by decapitation. Thus, artifacts resulting from use of anesthetics or tracer substances were avoided. In general, this study demonstrates important similarities between canine and human retinal vascular development, and this gives further reason to use of the puppy retina as a superior model for studying retrolental fibroplasia pathogenesis. This staining technique demonstrates undifferentiated cells in the avascular retina that appear to be vascular precursors or angioblasts. Primordial vessels form by organization of differentiating angioblasts that exist in peripheral retinal cystic spaces at birth, or by addition of fully differentiated endothelium; they form unlike neovascularization. Müller cell processes appear to provide a structural matrix throughout the avascular puppy retina on which differentiated angioblasts organize into a vascular network. Arteries develop in beds of primordial capillaries lying near the leading edge of the developing vasculature. This precedes vein formation which occurs through a process involving coalescence of embryonic capillaries which themselves were derived from primordial capillaries. Preliminary examination of eight mongrel kitten retinas prepared by this method clearly indicates that the puppy retina is much more completely vascularized at birth than that of the newborn kitten. Moreover, the rate of postnatal retinal vascularization is significantly faster in the kitten. The kitten vasculature does appear to form by the organization of angioblasts as in the puppy, but kitten angioblasts have a different appearance from those in the puppy.