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Biomedical subjects

L P Chong

Publications and source records attributed to L P Chong.

At least 19 recordsLinked to original sources
PubMed2001

Migration of intraocular silicone oil into the subconjunctival space and orbit through an Ahmed glaucoma valve.

PURPOSE: To report a patient with intraocular silicone oil migration into the subconjunctival space and orbit through an Ahmed glaucoma valve implant. METHODS: Observational case report. A 29-year-old female with diabetes mellitus and proliferative diabetic retinopathy underwent three left eye pars plana vitrectomies and ultimately intraocular silicone oil placement for tractional retinal detachment. Subsequently, she developed neovascular glaucoma and underwent an inferotemporal Ahmed glaucoma tube implant, left eye. RESULTS: Intraocular silicone oil migrated through the Ahmed glaucoma valve into the subconjunctival space and orbit. Left eye evisceration with silicone oil removal was performed for a blind painful left eye and improvement of appearance. CONCLUSION: Silicone oil migration through an Ahmed valve may be observed after retinal detachment repair with intraocular silicone oil. An Ahmed valve may be contraindicated in eyes of patients with intraocular silicone oil.

Adult↗
PubMed2001

Rifabutin-associated hypopyon uveitis in human immunodeficiency virus-negative immunocompetent individuals.

OBJECTIVE: To report the occurrence of rifabutin-associated hypopyon uveitis in human immunodeficiency virus (HIV)-negative immunocompetent individuals. DESIGN: Retrospective case series. PARTICIPANTS: Three HIV-negative subjects on rifabutin and clarithromycin for Mycobacterium avium complex infections with hypopyon uveitis are described. One subject was iatrogenically immunosuppressed because of a prior lung transplant. Two subjects had no known immunosuppressive conditions. INTERVENTION: Topical and regional steroid therapy. Discontinuation of rifabutin was required in two subjects. MAIN OUTCOME MEASURES: Visual acuity, resolution of hypopyon, anterior uveitis, and vitreitis. RESULTS: All subjects had resolution of hypopyon after therapy, two within 24 hours of beginning topical steroids. Vitreitis resolved with the discontinuation of rifabutin in two subjects. Chronic low-grade anterior uveitis and vitreitis were observed in the remaining subject, whose rifabutin dose was lowered but not discontinued because of active Mycobacterium avium complex osteomyelitis. CONCLUSIONS: Rifabutin-associated uveitis is well described in HIV-positive individuals, but it has been reported only once in an HIV-negative individual. We report two cases of hypopyon uveitis in immunocompetent individuals and one case in an immunosuppressed HIV-negative individual. All three subjects were receiving concurrent rifabutin and clarithromycin. Awareness that this entity can occur in HIV negative and nonimmunosuppressed individuals and that it can mimic infectious endophthalmitis may spare the subject from an invasive workup of systemic infection.

Administration, Topical↗
PubMed1999

Clinical study of combined penetrating keratoplasty, pars plana vitrectomy with temporary keratoprosthesis, and pars plana seton implant.

PURPOSE: To assess the effectiveness of a combined procedure (pars plana vitrectomy with temporary keratoprosthesis, penetrating keratoplasty, and pars plana seton implant) in preserving vision and controlling intraocular pressure (IOP). METHODS: We reviewed the course of visual acuity, IOP, graft clarity, retinal status, and complications in 18 patients who underwent the above procedure during one operating sitting. RESULTS: Preoperative diagnoses were varied. The majority of patients had pseudophakic bullous keratopathy and failed corneal transplants with glaucoma. Preoperative mean visual acuity was hand motions. Preoperative mean IOP was 27+/-13 mm Hg. Initially, all patients had attached retina. With a mean follow-up of 17+/-9 months, six patients had improved vision greater than 2 lines and 10 had unchanged vision. Only two patients lost vision greater than 2 lines. The final average IOP was 16+/-6 mm Hg and only one eye had a pressure above 22 mm Hg. Three eyes were classified as complete failures; two of the three became phthisical. Two patients developed rhegmatogenous detachments requiring further surgery. CONCLUSION: The combined procedure offers reasonable improvement in vision, good pressure control, and a tolerable number of complications. It is a useful procedure in eyes that probably would not have been treatable otherwise.

Adolescent↗
PubMed1997

Anterior segment prosthesis development: retinal function following anterior segment removal.

Replacement of the entire anterior segment of the eye is a very ambitious and complex endeavor and it is not known whether the retina remains functional when the anterior structures have been removed. We used routine histo-pathologic evaluation and electroretinographic measurements to determine the structural and functional status of rabbit retinas following surgical removal of the internal anterior structures (iris, ciliary body, and lens) and replacement of the vitreous with silicone oil. In some cases, we were able to record both a scotopic and a photopic electroretinographic response as long as 15 weeks after complete removal of the internal anterior segment structures. Although many hurdles remain and more efficacious surgical techniques and biomaterials need to be developed, our results suggest that, in the rabbit, the retina may continue to function in the absence of critical anterior segment structures.

Animals↗
PubMed1996

Use of the ganciclovir implant in the treatment of recurrent cytomegalovirus retinitis.

OBJECTIVE: To evaluate the efficacy of the ganciclovir implant in the treatment of recurrent cytomegalovirus (CMV) retinitis. METHODS: Patients with acquired immunodeficiency syndrome and recurrent CMV retinitis were evaluated for entry into the study. A ganciclovir implant was inserted in 91 eyes of 70 patients between October 1992 and October 1995. The efficacy of the implant and visual results were retrospectively reviewed. RESULTS: Fifty-three (76%) of 70 eyes had inactive CMV retinitis 1 month postoperatively (positive initial response). Twenty-one eyes of 19 patients had less than 1 month of follow-up. Nineteen (36%) of 53 eyes developed recurrent CMV retinitis. The median time to recurrence for those patients with a positive initial response was 7 months. Forty-eight (84%) of 57 patients with follow-up longer than 1 month after implant insertion in the first eye received systemic anti-CMV medication during the study. The cumulative risk for developing a retinal detachment was 23% at 6 months following implant insertion. Other complications included vitreous hemorrhage, hyphema, and suprachoroidal implantation of the device. CONCLUSION: The ganciclovir implant is effective as an adjunct to continued systemic therapy in those patients with recurrent CMV retinitis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Cytomegalovirus papillitis in patients with acquired immune deficiency syndrome. Visual prognosis of patients treated with ganciclovir and/or foscarnet.

BACKGROUND: Of those patients with acquired immune deficiency syndrome in whom cytomegaloviral retinitis develops, cytomegaloviral papillitis reportedly develops in up to 4% as well. Although occasionally patients have a good visual outcome, the majority have a poor visual prognosis, with a visual acuity of 20/200 or worse, even with treatment. METHODS: To evaluate the effects of prolonged induction with foscarnet or ganciclovir on the visual prognosis of cytomegalovirus (CMV) papillitis, the records of 22 patients seen between 1990 and 1995 at the Los Angeles County-University of Southern California Eye Clinic were reviewed. Papillitis was defined as greater than 270 degrees of disc edema/blurring of the disc margins as seen on direct examination and on color fundus photographs. RESULTS: Eighteen patients with a mean initial visual acuity of 20/69 (range, 20/ 15-20/400) were treated with induction doses of intravenous ganciclovir (range, 5-7.5 mg/kg twice daily) or foscarnet (range, 60-90 mg/kg twice or 3 times daily) for a mean of 3.3 weeks. The mean follow-up period was 4.8 months (range, 1-13 months). These patients maintained a mean final visual acuity of 20/68 (range, 20/ 25-20/400) with greater than 90% resolution of the papillitis. The remaining four patients had poor outcomes (visual acuity < 20/400) because of progressive CMV papillitis or retinitis. The median survival time was 4.5 months from the diagnosis of papillitis, but 7 months from the onset of CMV ocular infection. CONCLUSION: Patients with CMV papillitis have good visual prognosis when managed with high and prolonged doses of intravenous foscarnet and/or ganciclovir.

AIDS-Related Opportunistic Infections↗
PubMed1995

Clinicopathologic study of retinal and choroidal biopsies in intraocular inflammation.

PURPOSE: We reviewed the clinical and histopathologic features of 33 intraocular tissue biopsy specimens from 32 patients and assessed the value of retinal and chorioretinal biopsies performed in patients with intraocular inflammation. METHODS: Twenty-four endoretinal biopsies and nine chorioretinal or choroidal biopsies were performed. On the basis of clinical indications, the specimens were processed for light microscopy, electron microscopy, immunohistochemical staining, in situ DNA hybridization, and polymerase chain reaction. RESULTS: Of the 24 endoretinal biopsy specimens, 19 were from patients with clinical signs suggestive of viral retinitis. Overall, the diagnosis of viral retinitis was suggested by electron microscopy, immunohistochemical staining, in situ DNA hybridization, or polymerase chain reaction in 53% (ten of 19) biopsies. The preoperative diagnosis was confirmed in seven of ten biopsies in cases of suspected cytomegalovirus retinitis, in one of seven biopsies in cases of suspected acute retinal necrosis, and in two of two biopsies in cases of progressive outer retinal necrosis. The remaining five endoretinal biopsies disclosed Candida in one specimen, subretinal fibrosis in one, and chronic inflammation in three. Histologic examination of the nine chorioretinal or choroidal biopsies disclosed lymphoma in two specimens, a subretinal neovascular membrane in one, uveal melanocytic proliferation in one, toxoplasmic retinochoroiditis in one, viral retinitis in one, and long-standing inflammation in three. CONCLUSION: In select cases of intraocular inflammation, intraocular tissue biopsies may provide clinically useful information.

Adolescent↗
PubMed1994

New stroboscopic light source for intraoperative retinal fluorescein angiography.

We tested a new stroboscopic light source for intraoperative fluorescein angiography. A pulsed xenon light source and narrow-band interference filters are coupled to a 20-gauge endoilluminator and a 35-mm camera mounted on a surgical microscope. The system was tested with good success in a patient undergoing penetrating keratoplasty. An 18- to 22-microJ flash of 2 milliseconds' duration is achieved, which is well below the safety threshold level. This new stroboscopic light source provides a flash of sufficient light intensity to perform high-resolution, high-contrast fluorescein angiography during operations for the removal of opacified media.

Aged↗
PubMed1994

Encircling panretinal laser photocoagulation may prevent macular detachment after vitrectomy for proliferative diabetic retinopathy.

Macular detachment due to peripheral retinal tears that occur after pars plana vitrectomy for proliferative diabetic retinopathy can result in severe visual loss despite successful retinal reattachment. The authors reviewed the records of three patients who developed peripheral sclerotomy-related rhegmatogenous retinal detachments one to six months after vitrectomy for proliferative diabetic retinopathy, despite the absence of detectable sclerotomy-related retinal tears by indirect ophthalmoscopy and scleral depression at the conclusion of surgery. All three patients had received standard panretinal laser photocoagulation in a complete encircling pattern either prior to or during the initial vitrectomy. Clinically or echographically, each patient was seen to have a partial or complete annual peripheral sclerotomy-related rhegmatogenous retinal detachment delimited to the equator. In each of these three cases, posterior extension of the peripheral retinal detachment into the macular area was prevented by the most anterior row of the photocoagulation scars. Standard panretinal laser photocoagulation applied in a complete encircling pattern may be useful in the prophylaxis of macular detachment from sclerotomy-related retinal tears that occur after vitrectomy for proliferative diabetic retinopathy.

Aged↗
PubMed1993

Subretinal neovascular membranes in Vogt-Koyanagi-Harada syndrome.

Subretinal neovascular membranes cause late visual loss and are important determinants of final visual acuity in patients with Vogt-Koyanagi-Harada syndrome. The purpose of this study was to determine the prevalence and risk factors associated with the development of subretinal neovascular membranes in Vogt-Koyanagi-Harada syndrome. We reviewed the charts of 58 patients (116 eyes) with Vogt-Koyanagi-Harada syndrome. We separated patients into two groups, one with and one without subretinal membranes. Demographic characteristics, namely age, gender, and race, initial and final visual acuities, duration and method of treatment, anterior chamber and vitreous cell, presence of fundus pigmentary disturbances, and phase of inflammation, were evaluated for each group. Overall, ten eyes (9%) of seven patients developed the subretinal neovascular membranes. Demographic characteristics among the two groups of patients were not markedly different (P > .10). Visual outcome of patients with subretinal membranes was significantly poorer than was that of patients without these membranes (P < .001). Eyes with subretinal membranes had a significantly greater degree of anterior chamber and vitreous inflammation (P < .02), greater incidence of fundus pigmentary disturbances (P < .02), and a greater frequency of chronic recurrent phase of inflammation, marked by recurrence of predominantly anterior chamber, and occasionally posterior segment, inflammation (P < .02). The membranes were located in the peripapillary (four eyes), subfoveal (three eyes), and macular extrafoveal (three eyes) regions.

Adult↗
PubMed1993

Indocyanine green-enhanced diode laser treatment of melanoma in a rabbit model.

Indocyanine green (ICG)-enhanced laser therapy was evaluated for the treatment of experimental intraocular melanoma. Immediately after an intravenous injection of ICG, a 790-nm chromophore, 810-nm semiconductor diode laser was used to irradiate Greene hamster melanomas that had been implanted in the iris of rabbits. ICG-enhanced laser treatment of melanoma (14 eyes) was compared with treatment by laser alone (4 eyes), ICG alone (1 eye), and no treatment (2 eyes). Tumors treated with ICG-enhanced laser showed no growth after treatment, as judged by clinical examination and photography. Histologically, 4 of the 14 tumors treated with ICG-enhanced laser showed total necrosis, whereas the remaining 10 tumors treated similarly demonstrated only rare viable cells around blood vessels or at the tumor periphery. Laser treatment without ICG enhancement resulted in only superficial tumor necrosis, and all four of these tumors continued to grow after treatment. With further evaluation, indocyanine green in combination with a commercially available diode laser may be useful in the treatment of ocular melanoma.

Animals↗
PubMed1992

Vitrectomy for perforating eye injuries from shotgun pellets.

Pars plana vitrectomy and scleral buckling were performed on 22 eyes of 19 patients for treatment of perforating eye injuries from shotgun pellets. We reviewed the intraoperative findings at the time of vitrectomy to determine what factors might influence final visual acuity. The presence of a total retinal detachment at vitrectomy portended a poor prognosis when compared with eyes without total retinal detachment, as only one of ten eyes with total retinal detachment obtained useful vision (P = .002). Preoperative separation of the posterior vitreous was associated with a favorable outcome when compared with the absence of posterior vitreous detachment (P = .035), as ten of 16 eyes with posterior vitreous detachment at the time of vitrectomy ultimately achieved functional vision. The locations of the exit wounds did not affect visual success in the overall series of patients. However, in the patients who achieved visual success, exit wounds outside the vascular arcades were more likely to be associated with final visual acuities of, or better than, 20/70 than were those within the arcades (P = .022). Other prognostic factors, such as the number of perforations and the use of cryotherapy, were also examined for their effects on final visual outcome. However, these factors did not appear to affect visual outcome statistically.

Adolescent↗
PubMed1992

Ichthyoses and hyperkeratotic disorders.

Many of the ichthyotic disorders have characteristic ocular findings. These disorders include X-linked ichthyosis, lamellar ichthyosis, Sjögren-Larsson syndrome, KID syndrome, Refsum's disease, neutral lipid storage disease, chondrodysplasia punctata, and Richner-Hanhart syndrome. A knowledge of the ocular manifestations may provide a valuable aid to diagnosis in difficult cases. In some cases, knowledge of the ocular complications results in early referral for optimal ophthalmologic care.

Cataract↗