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Biomedical subjects

B C Joondeph

Publications and source records attributed to B C Joondeph.

34 records · Page 2Linked to original sources

Transscleral contact retinal photocoagulation with an 810-nm semiconductor diode laser.

Since the 810-nm wavelength has marked transmissibility through the sclera and absorption by melanin, it would be ideal for transscleral photocoagulation. We performed experiments to determine if consistent transscleral chorioretinal lesions could be produced in Dutch belted pigmented rabbits using the 810-nm laser, and if this modality caused less blood-retinal barrier disruption than retinal cryopexy of clinically equivalent treatment areas. The laser applications produced whitish to grayish-white retinal lesions when the surgeon, under direct visualization, used low powers and long durations (5 to 10 seconds), and controlled the treatment duration. Histopathologic evaluation of a lesion demonstrated an intact sclera overlying the chorioretinal lesion. Vitreous protein concentration, which was measured to assess blood-retinal barrier disruption, was significantly less in eyes treated with transscleral photocoagulation than in eyes treated with cryopexy of clinically equivalent treatment areas. We conclude that transscleral 810-nm laser treatment may be a viable clinical alternative to retinal cryopexy.

Animals↗

The surgical management of giant retinal tears with the cannulated extrusion needle.

In 18 eyes of 17 patients, we treated retinal detachment caused by a giant retinal tear by unfolding and repositioning the retina with a cannulated extrusion needle. After pars plana vitrectomy, a fluid-gas exchange was performed with the patient in the supine position. Using the cannulated extrusion needle to drain subretinal fluid posterior to the giant retinal tear, the retinal flap was manipulated into the correct anatomic position. With this technique, 18 of 18 eyes with retinal detachment caused by a giant retinal tear were successfully reattached intraoperatively. Although eight of these eyes subsequently redetached and required additional surgical procedures, 16 of 18 eyes remain attached with a mean follow-up of 11 months.

Adult↗

A new culture method for infectious endophthalmitis.

We studied the use of blood culture bottles for culturing vitreous specimens obtained during vitrectomy for infectious endophthalmitis. In a retrospective review of 83 cases, blood culture bottles yielded a 91% incidence of positive cultures. A laboratory comparison of direct media inoculation, a membrane filter system, and three blood culture systems was undertaken using inocula of nine organisms in three different concentrations. The blood culture bottle systems became positive at the same time as, or within 24 hours of, the membrane filter system for nearly every organism tested. A prospective clinical comparison was also performed in 14 cases of endophthalmitis, confirming our laboratory findings. The direct inoculation of blood culture bottles may be an acceptable adjunct or alternative to more sophisticated laboratory techniques for vitreous cultures in infectious endophthalmitis.

Adolescent↗

Hemostatic effects of air versus fluid in diabetic vitrectomy.

The potential hemostatic effect of an intravitreal air bubble after diabetic vitrectomy was studied in an animal model and in a randomized clinical trial. One day after vitrectomy with induced intraoperative hemorrhage, vitreous cavity hemorrhage was present in 60% of air-filled rabbit eyes compared with 27% of fluid-filled eyes. The prevalence and extent of hemorrhage was equal in the two groups on postoperative days 3 and 7. In a clinical trial of 51 eyes undergoing diabetic vitrectomy, 70% of eyes randomized to air-filled vitreous cavity after vitrectomy had vitreous cavity hemorrhage on postoperative day 1 compared with 50% of fluid-filled eyes. At 1 week, the incidence of hemorrhage was 78% for air and 61% for fluid. The 6-month visual and anatomic results were similar in both groups. These findings suggest that an intravitreal air bubble neither improves hemostasis nor reduces the visual outcome after diabetic vitrectomy.

Adult↗

Familial iris melanosis--a misnomer?

Iris melanosis is an unusual condition characterised by the presence of minute, discrete, pigmented elevations arising from the anterior surface of the iris. We encountered two unrelated Mexican families in which all children, but no parent, had varying degrees of the condition bilaterally. Some family members also gave findings suggestive of ocular hypertension. No family member had any other ocular or cutaneous pigmentary changes with the exception of a hairy naevus on the thigh of one member. To our knowledge these are the first families reported with more than one member having isolated iris melanosis. This is also the first report of a possible relationship with ocular hypertension. Finally we suggest that the term 'melanosis' may be a misnomer, since the condition is characterised not by abnormal iris hyperpigmentation but by discrete, round elevations on the anterior iris surface.

Adolescent↗

Retinal macroaneurysms treated with the yellow dye laser.

Retinal macroaneurysms, and their sequelae of retinal hemorrhage, exudate, edema, and serous detachment of the macula, may lead to decreased central visual acuity. We studied twelve patients with retinal macroaneurysms and decreased or threatened central vision who underwent laser photocoagulation of the macroaneurysm using the yellow (577 nm) wavelength of an ophthalmic tunable dye laser. In all cases, the macroaneurysm was "obliterated", with resolution of hemorrhage, exudate, edema, or serous macular detachment; in eight of the twelve cases, the visual acuity improved following treatment. There were no complications due to the photocoagulation.

Aged↗

Posterior tractional retinal breaks complicating branch retinal vein occlusion.

A total of 358 patients with branch retinal vein occlusion (BRVO) were reviewed to examine the relationship between branch retinal vein occlusion with neovascularization elsewhere (NVE), vitreous hemorrhage, and posterior tractional retinal breaks. Twenty-eight of 358 (7.8%) BRVO patients had vitreous hemorrhage. In this group of 28 patients, 24 of the 28 (85.7%) had NVE. Of the 24 BRVO patients with vitreous hemorrhage and NVE, six (21.4%) were found to have posterior tractional retinal breaks adjacent to avulsed neovascular tissue. These data indicate a strong association between BRVO patients with vitreous hemorrhage and posterior tractional retinal breaks due to avulsion of neovascular tissue.

Aged↗

Blunt ocular trauma.

The emergency medicine physician is encouraged to perform a brief eye history and examination on patients presenting with not only ocular but also multisystem trauma. Obviously, life-threatening conditions take precedence, but it is important to give attention to the ocular area once the patient is stabilized. The minor injuries can be treated initially in the emergency room and referred to an ophthalmologist for follow-up care. If, however, the emergency medicine physician has any doubts as to the nature or severity of the injury, appropriate ophthalmologic consultation should be sought. It is hoped that by taking a rational approach to blunt ocular trauma, as outlined in this article, the emergency medicine physician can provide emergency eye care in a confident and thorough manner.

Eye Injuries↗

Liposome-encapsulated 5-fluorouracil in the treatment of proliferative vitreoretinopathy.

Liposomes, small bilayer vesicles composed of phospholipids, can entrap and thus slow the release of drugs. We investigated the use of liposome-encapsulated 5-fluorouracil (5-FU), an antiproliferative agent, in the treatment of proliferative vitreoretinopathy (PVR) in an animal model. Doses of up to 1.6 mg administered intravitreally in rabbits demonstrated no retinal toxicity by histologic or electroretinographic criteria. In an experimental animal model of PVR, intravitreal injection of homologous rabbit corneal fibroblasts caused tractional retinal detachments in 90% of eyes after 4 weeks. The addition of 1.6 mg of liposome-encapsulated 5-FU decreased the rate of detachment to 32%, compared with 55% for 1 mg of free 5-FU. Thus, liposomal encapsulation of an anti-proliferative agent such as 5-FU may be a valuable adjunct to conventional vitreous surgery in managing PVR.

Animals↗

Foveal neovascularization in diabetic retinopathy.

Retinal neovascularization in diabetes mellitus almost always occurs at the optic disc and/or near the major nasal and temporal vascular arcades, sparing the foveal area. We examined seven eyes of seven patients with long-standing insulin-dependent diabetes mellitus who had unilateral foveal retinal neovascularization. The neovascularization originated from the perifoveal capillaries and demonstrated typical leakage on fluorescein angiography.

Adult↗

Purulent anterior segment endophthalmitis following paracentesis.

A 67-year-old man developed a central retinal artery occlusion and was treated with an oral carbonic anhydrase inhibitor, oral glycerin, carbachol rebreathing, and anterior chamber paracentesis. He subsequently developed an anterior segment endophthalmitis. Vigorous medical and surgical management cured the endophthalmitis, but his visual acuity remained at light perception. To the best of our knowledge, this patient represents the first reported case of a culture-positive, anterior segment endophthalmitis following anterior chamber paracentesis.

Aged↗

Variation in visual field measurements with an automated perimeter.

Using the Octopus automated perimeter, we conducted visual measurements on four separate occasions during a four-week period in six subjects with normal eyes. In 11 of 12 eyes, we found at least one point at which the threshold for light detection determined for that point showed a variance of more than 4 dB between tests. Thus, automated visual fields must be interpreted cautiously because an apparent pathologic change may only represent normal variation.

Adult↗