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Biomedical subjects

R L Peiffer

Publications and source records attributed to R L Peiffer.

At least 37 records · Page 2Linked to original sources
PubMed1991

Histopathologic study of uveitis in cats: 139 cases (1978-1988).

Histopathologic findings in 158 globes obtained from 139 cats by enucleation or at necropsy, with histopathologic diagnosis of uveitis, were compared, and morphology was correlated with clinical and/or histopathologic diagnosis. The most common morphologic feature was a lymphocytic-plasmacytic anterior uveal infiltrate that was either diffuse or nodular; specific cause could not be associated with this nongranulomatous anterior uveitis. In decreasing order of frequency, other common causes of uveitis in cats included feline infectious peritonitis; FeLV-associated lymphosarcoma; trauma; and lens-induced uveitis.

Animals↗
PubMed1991

Relationship of cell death to cyclophosphamide-induced ocular malformations.

C57BL/6J mice were used to study the ocular teratogenic effects of cyclophosphamide administered to pregnant females on d 9 of pregnancy at a dose of 5 mg/kg body weight. Nile blue staining demonstrated increased cell death at the base of the optic stalk, in the optic vesicle, and in the perivesicular mesenchyme in treated embryos. Malformations studied at gestational d 11 and 16 by light and scanning electron microscopy included microphthalmos, microphakia, and aphakia and were predictable based upon patterns of increased cell death. These anomalies are similar to those reported with exposure to ethanol or isotretinoin on gestational d 7.

Animals↗
PubMed1991

RPE dysplasia with retinal duplication in a mutant mouse strain.

An autosomal dominant mutation was produced by quadruple gonadal exposure of a male (C3H x 101)F1 mouse to 500 rad of X-irradiation. This mutation is maintained by the mating of affected heterozygous males to normal (C3H x C57B1)F1 females. Clinically apparent abnormalities were limited to the eyes and, in the affected adults, ranged from apparent anophthalmia to globes that were enlarged and exhibit large uveoscleral colobomas. Sequential evaluations of the embryogenesis of this condition have identified abnormal differentiation of the outer layer of the optic cup (presumptive retinal pigment epithelium-RPE) into a second layer of neural retina. The abnormality is identified as early as day 10 of gestation, during invagination of the optic cup and lens placode. The area of RPE dysplasia may be diffuse or regional with an abrupt transition from normal RPE and often demonstrates excessive and uncontrolled proliferation. The two symmetrical, apposed layers of photoreceptors fail to differentiate and begin to degenerate prenatally. Absence of normal RPE leads to failure of induction of adjacent choroid and sclera, resulting in a posterior segment consisting of a large neuroepithelial-lined cyst. Radiation-induced ocular malformations of this type have not been previously described. In addition, this model presents a unique opportunity to examine the processes leading to differentiation of a single, continuous epithelial layer into tissues as anatomically and functionally distinct as neural retina and RPE.

Animals↗
PubMed1991

Experimental evaluation of a phakic anterior chamber implant in a primate model. Part I. Clinical observations.

Anterior chamber intraocular lenses were implanted in phakic cynomolgus monkey eyes and followed clinically over two years. Significant observations included erosion and/or uveal envelopment of the haptic and a decrease in endothelial cell counts. There was good positional stability, no significant inflammation, initial ocular hypotension that returned to normal intraocular pressure, and no evidence of cataracts or cystoid macular edema.

Animals↗
PubMed1990

The causes of glaucoma in cats.

The cause of glaucoma in 131 enucleated eyes from 128 cats was determined in a retrospective histologic study. Obliteration of the ciliary cleft by diffuse iridal melanoma (38 eyes), or other neoplasms (14 eyes), or by the presence of idiopathic lymphocytic-plasmacytic anterior uveitis (53 eyes) were the most frequent lesions likely to explain the development of glaucoma. Secondary changes of inner retinal atrophy, optic disc cupping, scleral thinning with megaglobus, and atrophy of ciliary processes were similar to those described in dogs and human beings with chronic glaucoma. In light of the duration and severity of the glaucoma, the degree of inner retinal atrophy was often less than expected. Diffuse corneal edema and breaks in Descemet's membrane, changes typical of glaucoma in other species, were rarely detected. Eyes with chronic uveitis and glaucoma had collapsed ciliary clefts, iridoscleral adhesions, and posterior displacement of the iris. We were unable to determine whether these changes were consequences of the uveitis and thus responsible for the development of glaucoma, or if they were merely the result of the chronic glaucoma itself.

Animals↗
PubMed1990

The pathogenesis and significance of pre-iridal fibrovascular membrane in domestic animals.

Histologic examination was made of 1,419 globes from domestic animals (964 dogs, 374 cats, 41 horses, and 40 cattle) with ocular disease; pre-iridal membranes (rubeosis iridis) were found in 98. The membranes originated as endothelial budding from the anterior iridal stroma and seemed to mature into fibrous or fibrovascular membranes that were often followed by hyphema or, occasionally, glaucoma. Pre-existent disease in the 98 affected globes included chronic endophthalmitis (27/98), chronic glaucoma (24/98), anterior uveal melanoma (15/98), ciliary body adenoma (14/98), neoplasms metastatic to the eye (8/98), and chronic retinal detachment (6/98). In terms of likelihood of occurrence, pre-iridal membranes seen in 21% (6/21) of globes with retinal detachment, 19% (14/75) of those with ciliary body adenomas, 14% (24/167) of those with chronic glaucoma, and 10% (15/158) of those with anterior uveal melanoma. They were detected with greatest relative frequency in horses (9/41) followed by dogs (83/964), cats (5/374) and cattle (1/40). These membranes, which are rarely detected by clinical examination, probably form in response to angiogenic factors released by ischemic retina, by neoplasms, or by leukocytes involved in ocular inflammation.

Animals↗
PubMed1990

Tissue response to subtotal retinectomy in a rabbit model.

We surgically removed lenses and as much retina as accessible in one eye of six pigmented rabbits which were followed for up to four months postsurgically. Clinically, pre-RPE membranes were noted to form within the first weeks after surgery, and eyes remained hypotensive in the absence of notable inflammation. Morphologic studies demonstrated a variable response of RPE, ranging from atrophy to hypertrophy and hyperplasia. Pre-RPE membranes appeared to arise from both the RPE as well as from tags of peripheral retina and were of two morphologic types: spindle cell-collagenous membranes, and a highly cellular glial membrane. Bone formation within collagenous membranes was seen in four of six eyes studied.

Animals↗
PubMed1990

Selective photoreceptor cell loss in hypoxic ischemia.

We studied the histopathologic changes in the brain and eye of a 5 1/2-month-old infant who suffered a profound hypotensive episode three days antemortem. Nuclear pyknosis and other histologic changes characteristic of ischemic cell necrosis were found throughout the brain and in the retina's photoreceptor-cell layer. These findings suggest that hypoxic ischemia may produce preferential damage to the photoreceptor-cell layer.

Autopsy↗
PubMed1990

Large histiocytes in the choroid of leukemic patients.

We identified large histiocytes as a prominent feature in the choroid of eyes obtained at autopsy in seven of nine patients who died of leukemia. The eyes of four of the seven patients affected had leukemic choroidal infiltrates, and a majority had similar-appearing histiocytes identified in spleen or bone marrow. The significance of these cells is undetermined; we postulate that these macrophages are ingesting debris of degenerating leukemic cells.

Choroid↗
PubMed1990

Long-term comparative study of the Schocket and Joseph glaucoma tube shunts in monkeys.

Schocket and Joseph tube shunts were implanted in normal cynomolgus monkey eyes in order to compare the tissue response to the shunts as well as the pathways of aqueous flow associated with each. Following periods ranging from 5 to 10 months after implantation horseradish-peroxidase and/or fluorescein-labelled latex microspheres were inserted into the anterior chamber. The monkeys were then killed and the eyes studied by light, scanning, and transmission electron microscopy. In general, tissue responses to, and routes of aqueous flow associated with both shunts were similar: fibrous encapsulation of the drainage tubes and encircling bands, with aqueous flow through these fibrous capsules.

Animals↗
PubMed1989

Protective effects of viscous solutions in phacoemulsification and traumatic lens implantation.

We compared the endothelial protection offered by 1% hyaluronate sodium (Healon), 3% hyaluronate sodium and 4% chondroitin sulfate (Viscoat), and a nonviscous irrigating solution (BSS Plus) during phacoemulsification with and without traumatic intraocular lens implantation. Vital-dye staining and scanning electron microscopy were used to determine acute damage to rabbit corneal endothelium. Cell damage during phacoemulsification alone was not significantly different from that in unoperated controls (12.5%). Cell damage after traumatic lens insertion was significantly greater in the groups treated with BSS Plus (76.2%) and Healon (41.4%) than in either paired Viscoat-treated group (21.1% and 17.4%, respectively). Viscoat (but not Healon) was noted to be adherent to the cornea at the end of the procedure in one third of the cases, indicating that Viscoat remains in the anterior chamber during surgery. We attribute this to chondroitin sulfate's newtonian characteristics, allowing it to maintain viscosity in the face of high flow rates.

Animals↗
PubMed1989

Experimental evaluation of a synthetic viscoelastic material on intraocular pressure and corneal endothelium.

We compared the effects of 1.0% hyaluronic acid (Healon) and a synthetic viscoelastic polyacrylamide on postoperative intraocular pressure, the corneal endothelium, and various clinical parameters in rabbit and monkey models. Seven rabbit eyes received polyacrylamide and seven received hyaluronic acid during extracapsular cataract extraction with implantation of a polymethylmethacrylate posterior chamber intraocular lens. Intraocular pressure was measured preoperatively, immediately postoperatively, and at 1, 2, 4, 8, 12, and 24 hours postoperatively. Slitlamp examination was performed preoperatively and postoperatively at 3, 7, and 14 days. Axial corneal buttons were taken and scanning electron microscopy of the endothelium was performed. Sections of the globe were studied by light microscopy. Six monkey eyes received polyacrylamide, three received hyaluronic acid, and three received balanced salt solution to reform the anterior chamber after limbal incision with evacuation of aqueous. Intraocular pressure was measured preoperatively, postoperatively, and at 4, 8, 12, 24, and 48 hours postoperatively. Slitlamp examination was performed preoperatively, and at 1, 2, 7, and 14 days postoperatively. Specular endothelial microscopy was performed preoperatively and at 7, 14, and 90 days postoperatively. In the studies performed no significant difference between the eyes receiving polyacrylamide and hyaluronic acid was seen. In the rabbit and monkey models, polyacrylamide is as safe and biocompatible as hyaluronic acid.

Acrylamides↗
PubMed1988

Pluronic polyol: a potential alloplastic keratorefractive material.

Pluronic polyol possesses a negative temperature coefficient of gelation; it is liquid at low temperatures and gelatinous at high temperatures. Pluronic F108 was evaluated as a potential material for alloplastic keratorefractive surgery: 0.3 ml of the material in a liquid state was injected into a surgically prepared axial 7 mm mid-stromal corneal bed in 17 rabbits; fellow eyes in the rabbits were sham-operated but not injected. Postoperatively, rabbits were clinically evaluated with biomicroscopy, keratometry, and pachymetry at regular intervals up to three months following surgery. Animals were periodically sacrificed and corneas were studied by light and electron microscopy. The material appeared to be well tolerated by the cornea. Both control and pluronic eyes showed an initial increase in corneal thickness peaking at one week postoperatively, with return to near normal levels by the end of the third week. Refractive flattening of approximately three diopters was noted in the experimental group, while no change was seen in the control group.

Animals↗
PubMed1988

Pathogenesis of ciliary-body cysts associated with multiple myeloma.

A case history is presented which illustrates the occurrence of ciliary-body cysts in association with multiple myeloma. Gross pathologic, light-microscopic, ultrastructural, and immunofluorescent characteristics of the cysts are presented, and the observed morphology used to postulate their pathogenesis.

Ciliary Body↗
PubMed1987

Synthetic keratophakia for the correction of aphakia.

Although the majority of aphakic patients will have intraocular lens implants (IOLs), there are several groups of patients for whom IOLs are not indicated. Synthetic keratophakia for the correction of aphakia has several inherent advantages over alternative forms of refractive surgery which use lathed corneal tissue. For example, the ability to produce a synthetic lens to precise specifications before surgery is a dramatic advantage over the use of lathed tissue lenses whose refractive properties cannot be determined until weeks or months after the lens is in place on the recipient cornea. Synthetic materials appear to behave in a predictable manner and are biocompatible. Both polysulfones and hydrogel materials can be used to correct aphakia in clinical situations where other modalities are less appropriate.

Animals↗
PubMed1987

Comparison of the effect of polymethylmethacrylate and silicone intraocular lenses on rabbit corneal endothelium in vitro.

An in vitro comparison of corneal endothelial damage caused by polymethylmethacrylate and by silicone intraocular lenses was made. Endothelial damage was assessed by vital staining of corneal endothelium immediately following direct contact with an intraocular lens. Silicone lenses produced less damage than polymethylmethacrylate lenses. The difference could be attributed to a specific type of damage-membrane stripping-seen only after contact with polymethylmethacrylate lenses.

Animals↗