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Biomedical subjects

R N Mittl

Publications and source records attributed to R N Mittl.

14 recordsLinked to original sources

Perfluorocarbon gases in the suprachoroidal space of rabbit eyes.

Four perfluorocarbon gases were injected into the suprachoroidal space of rabbit eyes. Temporary, expanding choroidal detachments were observed in all cases. Depending on the amount of gas injected (0.1 or 0.2 cc, respectively), they lasted 1 or 2 days in the case of perfluoromethane, 4 or 5 days with perfluoroethane, 6 or 8 days with perfluoropropane, and 9 or 11 days with perfluoro-N-butane. Due to its longevity, perfluoro-N-butane appeared to be the most suitable gas for temporary "buckling" of the suprachoroidal space in rabbit eyes.

Animals↗

Endothelial cell counts following pars plana vitrectomy in pseudophakic and aphakic eyes.

In 13 pseudophakic eyes, endothelial cell counts remained stable following pars plana vitrectomy. The posterior chamber pseudophakos apparently had a protective effect on the corneal endothelium, even though the posterior lens capsule was removed during surgery. By contrast, in nine aphakic eyes, a statistically significant (p greater than .05) cell loss of 7.6% occurred after pars plana vitrectomy. We conclude that vitrectomy therefore poses an increased risk to the cornea in aphakic, but not in pseudophakic eyes.

Aged↗

Suprachoroidal injection of sodium hyaluronate as an 'internal' buckling procedure.

Various fractions of sodium hyaluronate were injected into the suprachoroidal space of rabbit eyes via the pars plana as 'internal' buckles. The areas of elevated choroid were diffuse, usually extending over approximately one quadrant. The buckling effect was short-lived, in the range of 12-72 h, but sodium hyaluronate actually survived in the suprachoroidal space up to 10-14 days or more. No significant differences between buckles created by sodium hyaluronate 1 and 2%, or by cross-linked sodium hyaluronate were observed. Internal buckling of the choroid may prove to be a viable adjunct or alternative to conventional buckling procedures in the future.

Animals↗

Blue field entoptoscopy in the preoperative evaluation of vitrectomy candidates.

Twenty-four patients with vitreous hemorrhage scheduled for pars plana vitrectomy were evaluated with the blue field entoptoscope. Correlation of pre- and postoperative findings in patients with and without macular pathology was highly irregular, apparently due to mechanical obstruction of light transmission by the vitreous hemorrhage. Blue field entoptoscopy is therefore not recommended as a tool in the preoperative evaluation of vitrectomy patients.

Evaluation Studies as Topic↗

Computer-assisted spectral electroretinography in vitrectomy patients.

Computer-assisted spectral electroretinography (CASE), using full field stimulation in the presence of a rod saturating background light, has been found to be a useful means of evaluating retinal function in patients with vitreal opacities. By this means, cone electroretinograms (ERGs) to white as well as spectrally selective stimuli could easily be detected in 22 of 24 eyes with vitreal opacities obscuring any view of the fundus and with minimal or no detectable ERGs to standard single flash stimuli. The responses to spectral stimuli in the presence of a rod saturating background light provides a means of estimating the optical density of the opacity. The results indicate that most patients undergoing vitrectomy for such opacities have considerable superimposed retinal damage and that the opacities themselves are seldom sufficiently dense to decrease the ERG to any great extent. Five eyes studied before and after vitrectomy indicate that successful vitrectomy has no effect on the ERG. The results suggest that CASE may be a useful substitute to the bright flash ERG for evaluating global retinal function behind an opaque media.

Adolescent↗

Carbon dioxide laser trabeculostomy for the treatment of neovascular glaucoma.

During the past 24 months, 23 cases of advanced neovascular glaucoma, unresponsive to medical therapy, have been treated by a trabeculostomy procedure using a carbon dioxide laser. This procedure entails surgical entry into the anterior chamber from beneath either a conjunctival or scleral flap in such a way as to completely cauterize any neovascular tissue in the corneoscleral angle and to permit adequate drainage of the aqueous in fluid from the anterior chamber to the periocular space. The average intraocular pressure prior to carbon dioxide laser trabeculostomy was 54 mmHg and these pressures were lowered below 18 mmHg in over 70% of the cases followed for longer than six months postlaser therapy. Treatment was considered a failure in 16% of the cases where the intraocular pressure was not lowered substantially. Fourteen percent of the treated eyes sustained a pressure decrease to within the 26-35 mmHg range. Carbon dioxide laser trabeculostomy provides a new method of lowering the intraocular pressure in severe cases of neovascular glaucoma without the hazard of intraocular hemorrhage common with other filtration procedures or the ciliary destruction present with the cyclocautery operations. The indications, surgical technique, and complications will be discussed.

Diabetic Retinopathy↗

Carbon dioxide laser trabeculostomy for the treatment of neovascular glaucoma.

During the past 18 months, 23 cases of advanced neovascular glaucoma, unresponsive to medical therapy, have been treated by a trabeculostomy procedure using a carbon dioxide laser. This procedure entails surgical entry into the anterior chamber from beneath either a conjunctival or a scleral flap in such a way as to completely cauterize any neovascular tissue in the iridocorneal angle and to permit adequate drainage of the aqueous fluid from the anterior chamber to the periocular space. The average intraocular pressure, prior to carbon dioxide laser trabeculostomy was 54 mm Hg and these pressures were lowered below 18 mm Hg in over 57% of the cases followed for longer than six months post-laser therapy. Treatment was considered a failure in 26% of the cases where the intraocular pressure was not lowered substantially, and 17% of the treated eyes sustained a pressure decrease to within the 25 to 35 mm Hg range. Carbon dioxide laser trabeculostomy or trabeculo-sclerostomy provides a new method of lowering the intraocular pressure in severe cases of neovascular glaucoma without the hazard of intraocular hemorrhage, common with other filtration procedures. These procedures have proved satisfactory in alleviating the high pressures of neovascular glaucoma in a relatively large proportion of the patients treated. If the eye is grossly hyperemic and irritated because of the high intraocular pressure and the deteriorated condition of the eye, it is suggested that the carbon dioxide laser trabeculostomy procedure with a scleral flap be performed with an implanted seton as the procedure of choice. If the eye is relatively quiet and has some visual reserve but an exceedingly high and intractable intraocular pressure, it is advisable to use either the carbon dioxide laser trabeculostomy procedure or the carbon dioxide laser trabeculo-sclerostomy operation as described. These procedures are being further refined, but the results of this investigation suggest that these procedures can be utilized judiciously, and should prove useful, particularly in those eyes with advanced neovascular glaucoma with useful vision still remaining.

Female↗

The disciform response: an historical perspective.

This paper is a survey of the literature in an attempt to provide the basis for our current understanding of the disciform process. Particular emphasis is placed on its pathogenesis and the role of subretinal neovascularization. No two lesions appear exactly alike because of the many stages and combinations possible. Gass (1967) has delineated the broad spectrum with the many different clinical manifestations of this disease process. Verhoeff and Grossman (1937) provided the histopathologic basis for our understanding of the disciform process. The histologic correlation of the clinical "predisciform" state would seem to offer the most promising information for understanding the pathogenesis of the disciform process (Frank et al. 1973; Green and Key 1977; Kornweig 1967; Sarks 1973 and 1976; Small et al. 1976; Zauberman 1970). It is hoped that this literature review has sufficiently emphasized the inherent deficiencies of strictly clinical studies and the need for an appropriate experimental animal model (Ryan 1979).

Aged↗

Enzymatic and mechanically induced subretinal neovascularization.

Mechanical and enzymatic disruption of Bruch's membrane and induction of subretinal neovascularization in an experimental primate model have produced limited success. The methods and results are reported here to identify some problems encountered in methodology and to detail the results of this approach to subretinal neovascularization.

Animals↗

Unsuspected fungal endophthalmitis diagnosed in vitrectomy specimen.

A vitrectomy specimen obtained with the roto-extractor from a diabetic patient with vitreous haemorrhage revealed fungal endophthalmitis on microscopical examination. Endophthalmitis was not suspected before the procedure. Extensive medical examinations failed to reveal any evidence of systemic fungal disease. The case exemplifies endogenous mycotic endophthalmitis of occult origin, the first of its kind, we believe, to be diagnosed in this manner.

Endophthalmitis↗

Blue field entoptoscopy in diabetic retinopathy.

Blue field entoptoscopy was performed in 50 consecutive patients with diabetic retinopathy. Several statistically significant correlations were obtained. The number of "flying corpuscles" was reduced in eyes harboring a vitreous hemorrhage, and in severe and proliferative diabetic retinopathy. On the other hand, patients with a history of focal or panretinal photocoagulation had better corpuscle counts than patients who had never received any treatment. It appears therefore, that argon laser photocoagulation is beneficial in preserving the blue field entoptic phenomenon.

Adult↗

Pars plana vitrectomy in the treatment of chronic aphakic cystoid macular edema.

Long-standing cystoid macular edema was evaluated in three groups of aphakic patients: Group A following vitrectomy, Group B without vitrectomy, and group C without vitrectomy but with associated background diabetic retinopathy. After a two-year follow-up period, no significant differences in resolution of cystoid macular edema and visual acuity were found between the three groups.

Aphakia, Postcataract↗