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Biomedical subjects

P F Lopez

Publications and source records attributed to P F Lopez.

At least 19 recordsLinked to original sources
PubMed2000

Vitrectomy update for macular traction in ocular toxocariasis.

PURPOSE: To study the results of modern vitrectomy in traction and combined traction-rhegmatogenous retinal detachment involving the macula in cases of ocular toxocariasis. METHODS: This was a cohort study of patients seen in different institutions in the United States. Ten eyes of 10 patients were studied. Vitrectomy was performed in all eyes, combined with membrane removal, scleral buckle, fluid-gas exchange, silicone oil, or lensectomy in certain cases. The anatomic and visual results of surgery were reviewed. RESULTS: Ten eyes from 10 patients ranging in age from 2 to 33 years (median, 6 years) were reviewed. Follow-up ranged from 3 months to 8 years (median, 2 years). All eyes achieved macular attachment following surgery; vision improved in 5 (50%) eyes, and was unchanged in 5 (50%). Histologic specimens from six eyes were reviewed, and revealed combinations of fibrous tissue, eosinophils, plasma cells, lymphocytes, and giant cells. One specimen revealed an encysted Toxocara canis organism. CONCLUSION: Inflammation created in response to Toxocara larvae may lead to traction retinal detachment of the macula. Vitreoretinal surgery has a good chance of reattaching the macula and improving vision.

Adolescent↗
PubMed1998

Advanced glycation end products in age-related macular degeneration.

OBJECTIVE: To investigate the localization of N epsilon-(carboxymethyl)lysine (CML), a component and major immunologic epitope of advanced glycation end products, in aged eyes and choroidal neovascular membranes (CNVMs) surgically excised from eyes with age-related macular degeneration. METHODS: Immunohistochemistry for CML was performed using 8 snap-frozen, surgically excised CNVMs. Twelve eyes from patients aged 69 to 82 years and 2 donor eyes, 1 each from a 23-week-old fetus and 21-year-old patient, without age-related macular degeneration or diabetic retinopathy were also examined. To determine if retinal pigment epithelial cells in CNVMs accumulate advanced glycation end products, cytokeratin and CML were stained in paired serial sections. RESULTS: Soft, macular drusen and/or basal laminar and basal linear deposits were observed in 8 of 12 aged eyes. Each case showed CML accumulation, while overlying retinal pigment epithelial cells showed no accumulation in all 12 eyes. In CNVMs, however, retinal pigment epithelial cells showed CML accumulation in their cytoplasm. CONCLUSION: The additional accumulation of advanced glycation end products in soft, macular drusen and/or retinal pigment epithelial cells may play a role in the pathogenesis of CNVM formation in age-related macular degeneration. CLINICAL RELEVANCE: Recently, advanced glycation end products have been found to play a role both in aging changes and neovascularization. Localization of advanced glycation end products in the above-mentioned tissue may lead to a better understanding of the pathogenesis of age-related macular degeneration.

Adult↗
PubMed1998

Apoptosis in surgically excised choroidal neovascular membranes in age-related macular degeneration.

BACKGROUND: Choroidal neovascular membranes (CNVMs) in age-related macular degeneration show progressive histologic changes from active, cellular, highly vascularized membranes to inactive paucicellular scars. The purpose of this study was to determine whether apoptosis was involved in the evolution of these changes, what cell types are involved, and whether there was an association with the Fas antigen (Fas or CD95) and Fas ligand (FasL). METHODS: Serial frozen sections from 10 surgically excised CNVMs were stained by the TUNEL (terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine 5-triphosphate nick-end labeling) method for detection of DNA strand breaks and by propidium iodide staining for morphologic detection of apoptosis. Immunoperoxidase staining was used for detection of Fas, FasL, and cell-type specific antigens. RESULTS: Highly vascularized membranes contained cells with TUNEL-positive nuclei, particularly in the regions of neovascularization, while fibrotic membranes showed few, if any, TUNEL-positive cells. Many of the TUNEL-positive cells were stromal retinal pigment epithelial cells, although smaller numbers were identified as endothelial cells and macrophages. Confocal microscopy of propidium idoide-stained sections confirmed the presence of apoptotic nuclei. The extent of Fas antigen expression correlated with extent of apoptosis. FasL expression was found in all specimens but was most intense in the highly vascularized membranes. CONCLUSIONS: Highly vascularized CNVMs related to age-related macular degeneration show apoptosis in stromal retinal pigment epithelial cells, endothelial cells, and occasional macrophages. Apoptosis is associated with prominent Fas and FasL expression.

Aged↗
PubMed1997

Scanning and transmission electron microscopic findings during RPE wound healing in vivo.

OBJECTIVE: To examine the scanning (SEM) and transmission (TEM) electron microscopic features of an in vivo rabbit model of retinal pigment epithelial (RPE) wound healing. METHODS: Hydraulic debridement of the RPE was performed in one eye of each of 35 pigmented rabbits using a pars plana vitrectomy approach. Five of the 35 eyes were examined by either SEM or TEM on each of the following postoperative days: 0, 2, 4, 7, 14, 28 and 56. RESULTS: TEM revealed that hydraulic RPE debridement results in only focal damage to the RPE basement membrane portion of Bruch's membrane and that this damage is repaired by day 7 without ultrastructural sequelae. SEM and TEM disclosed that the RPE cells at the margin of the debrided bed become flattened and enlarged and evolve a cytoskeletal reorganization with altered apical-basal polarity consistent with the development of a migrating phenotype. This is followed by gradual restoration to a more normal stationary RPE phenotype after initial closure (reepithelialization) of the RPE defect on day 7. RPE hyperplasia also occurs and may contribute to this repair process. Tight junctions are re-established among the apical surfaces of monolayered and multilayered RPE cells by day 7, coinciding with the restoration of the blood outer retinal barrier. CONCLUSION: Hydraulic debridement of the RPE in vivo is a useful investigational model that provides important insight into the pathogenesis of outer retinal disorders and their treatment with such techniques as submacular surgery or RPE transplantation.

Animals↗
PubMed1997

Retinal manifestations of acute murine typhus.

PURPOSE: To report the ocular manifestations of acute serologically confirmed murine typhus. METHODS: A retrospective analysis of the clinical history, photography and fluorescein angiography of two patients with acute murine typhus with ocular involvement was conducted. RESULTS: A 38 year old male and a 49 year old female were included in the study. Both complained of fever, headache, rash, night sweats and pulmonary symptoms. They had noted the recent onset of diminished visual acuity and floaters. Examination of the posterior pole revealed mild optic nerve head edema (in one patient), intraretinal hemorrhages and small localized areas of retinal whitening. The history confirmed that both patients had been exposed to fleas and the serologic testing was positive for Rickettsia typhi. The systemic and ocular findings resolved after the use of systemic antibiotics. CONCLUSION: Rickettsial diseases such as murine typhus should be included in the differential diagnosis of otherwise healthy individuals who present with an acute systemic febrile illness and retinitis or neuroretinitis. SUMMARY STATEMENT: The clinical features of two patients with serologically proven acute murine typhus with ocular involvement are presented. Both patients presented with a retinal whitening that resolved after treatment.

Acute Disease↗
PubMed1996

The prognostic utility of the Silicone Study Classification System. Silicone Study Report 9. Silicone Study Group.

OBJECTIVE: To evaluate the reproducibility and the prognostic utility of the Retina Society and Silicone Study Classification Systems in eyes after surgery for severe proliferative vitreoretinopathy (PVR). DESIGN: Subgroup analysis of the Silicone Study--a randomized, multicentered, surgical trial. SETTING: Community and university-based ophthalmology clinics. MATERIALS: Three hundred forty eyes with preoperative and intraoperative evaluations using both systems of grading PVR (reproducibility study), and 287 eyes with preoperative and intraoperative evaluations using both systems of grading PVR and with a 24-month follow-up examination (prognosis study). INTERVENTIONS: Vitrectomy for PVR with long-acting perfluoropropane gas or silicone oil as the intraocular tamponade. OUTCOME MEASURES: Retinal reattachment, visual acuity ( > or = 5/200), intraocular pressure, corneal clarity, and the need for reoperation. RESULTS: The reproducibility of the Silicone Study Classification System was 64% (type of contraction), 77% (number of clock hours), 67% (posterior PVR), 88% anterior and posterior PVR), and 94% (anterior, posterior, and subretinal PVR). The reproducibility of the Retina Society Classification System was 99%. Using the Silicone Study Classification System, location of PVR predicted visual acuity (P=.004, chi 2 test for trend) and hypotony (P=.03, chi 2 test for trend). Using the Retina Society Classification System, the grade of PVR predicted only visual acuity (P=.01, chi 2 test for trend). For eyes with anterior and posterior PVR, there was a decreasing trend in successful visual acuity outcome with increasing severity of PVR (from C-3 to D-3, P=.02, chi 2 test for trend). CONCLUSIONS: Although the classification of PVR using the Silicone Study classification System was not reproducible for the type of contraction or for posterior PVR, identification of the anteroposterior extent of the PVR was prognostic of visual acuity and hypotony at 24 months. The joint knowledge of the location of PVR (using the Silicone Study Classification System) and the tightness of the funnel for retinas with 9 to 12 clock hours involved by fixed folds (using the Retina Society Classification System) has prognostic utility for eyes with anterior and posterior PVR.

Adult↗
PubMed1996

The effects of California Proposition 187 on ophthalmology clinic utilization at an inner-city urban hospital.

PURPOSE: To determine the effect on ophthalmology clinic utilization at a major public inner-city hospital of California Proposition 187 and the debate surrounding its passage. Proposition 187 was a statewide referendum passed by 63% of the electorate in the November 1994 election that would restrict social services to undocumented immigrants and require providers to report them to immigration authorities. METHODS: The ophthalmology clinic volume at the Los Angeles County/ University of Southern California Medical Center was analyzed from October 1 to December 31, 1993 and 1994. RESULTS: New walk-in patients significantly decreased (P < 0.001) for a 2-month period around the election, but returned to baseline levels in December 1994. The new patient cancellation and no show rate was not affected. No change in return patient behavior was noted for general and specialty clinics. CONCLUSIONS: Proposition 187 may have caused a statistically significant decrease in new walk-ins to the ophthalmology clinics during a 2-month period surround the November 1994 election, but it had no measurable effect on other indicators of utilization. In addition, utilization rates returned to baseline after the implementation of Proposition 187 was stayed by the judicial system, and concern that providers would be required to report undocumented immigrants to authorities was alleviated.

Appointments and Schedules↗
PubMed1996

Posterior vitreoschisis. An echographic finding in proliferative diabetic retinopathy.

PURPOSE: To describe the echographic characteristics of splitting the outer posterior cortical vitreous in patients with proliferative diabetic retinopathy and vitreous hemorrhage. METHODS: The authors retrospectively reviewed the echographic findings in 270 patients who were evaluated at the Doheny Eye Institute between January 1983 to December 1989 for proliferative diabetic retinopathy and vitreous hemorrhage. None of the eyes had undergone pars plana vitrectomy before echographic examination. RESULTS: Forty-five patients (17%) had echographic evidence of splitting of the outer posterior vitreous cortex, a finding the authors have termed posterior vitreoschisis. In all patients, differentiation of the posterior vitreoschisis from a true posterior hyaloid detachment was possible, either on the initial or on serial echographic examination, by the separate detachment of the inner wall of the vitreoschisis cavity and the true posterior hyaloid from the retinal surface. The vitreoschisis cavities often were found to contain unclotted blood. In some eyes, the inner wall of the vitreoschisis cavity was adherent to the apex of the most highly elevated area of traction retinal detachment, suggesting that posterior vitreoschisis may itself result in clinically significant vitreoretinal traction, independent of the presence or extent of true posterior hyaloid separation. CONCLUSIONS: The authors' finding suggest that spontaneous splitting of the outer posterior vitreous cortex may occur in patients with proliferative diabetic retinopathy and vitreous hemorrhage, which may mimic a true posterior cortical vitreous detachment on echographic examination. Preoperative recognition of posterior vitreoschisis may be important in the surgical management of these patients.

Adult↗
PubMed1996

Transdifferentiated retinal pigment epithelial cells are immunoreactive for vascular endothelial growth factor in surgically excised age-related macular degeneration-related choroidal neovascular membranes.

PURPOSE: To determine the cellular origin and the vascular endothelial growth factor (VEGF) immunoreactivity of the nonvascular stromal cells in surgically excised age-related macular degeneration (ARMD)-associated choroidal neovascular membranes (CNVMs). METHODS: Immunohistochemical analysis was performed on frozen sections of eight surgically excised ARMD-related CNVMs. RESULTS: Cytokeratin-positive, smooth muscle actin-positive polygonal or fibroblastic (transdifferentiated RPE) cells were the principal nonvascular stromal cells detected. The polygonal cells were more commonly found in active (highly vascularized) regions and were strongly immunoreactive for VEGF. The fibroblastic cells were predominantly found in fibrotic (hypovascular) regions and were minimally immunoreactive for VEGF. CONCLUSIONS: Transdifferentiated RPE cells are the principal nonvascular stromal cells of both vascular and fibrotic ARMD-related CNVMs. Preferential localization of VEGF immunoreactivity with the cytoplasm of the polygonal transdifferentiated RPE cells in the highly vascularized regions of the surgically excised CNVMs suggests an important angiogenic role of these cells and this growth factor in the progression of ARMD-related choroidal neovascularization.

Actins↗
PubMed1995

Retinal pigment epithelial wound healing in vivo.

OBJECTIVE: To develop an in vivo rabbit model of retinal pigment epithelial wound healing that preserves the overlying retina. METHODS: Hydraulic débridement of the retinal pigment epithelium was performed in one eye of 35 pigmented rabbits by means of a pars plana vitrectomy approach. Five of the 35 eyes were examined by stereoscopic color fundus photography, fluorescein angiography, and light microscopy on each of the following postoperative days: 0, 2, 4, 7, 14, 28, and 56. RESULTS: Retinal pigment epithelial débridement with this technique results in apical decapitation of the retinal pigment epithelial cells followed by subsequent hydraulic removal of the residual nucleus-containing basal cellular debris. The retinal pigment epithelium-denuded Bruch's membrane was resurfaced mostly by a monolayer of flattened, hypopigmented retinal pigment epithelial cells within 4 days after débridement. Progressive retinal pigment epithelial hyperplasia also occurred beginning between postoperative days 2 and 4. CONCLUSIONS: Retinal pigment epithelial wound healing after hydraulic débridement occurs rapidly and in a manner initially consistent with sliding migration. Progressive retinal pigment epithelial hyperplasia also occurs and may contribute to this repair process. Further investigation of retinal pigment epithelial repair by means of this in vivo model may provide important insight into the pathogenesis and treatment of outer retinal disorders.

Animals↗
PubMed1995

Delayed macular choriocapillary circulation in age-related macular degeneration.

PURPOSE: To investigate the macular choriocapillary circulation (MCC) in eyes with age-related macular degeneration (ARMD) and to correlate these findings with the associated clinical and angiographic drusen characteristics. METHODS: Scanning laser ophthalmoscope fluorescein videoangiography was performed on 34 eyes with age-related macular degeneration and eight age-matched normal volunteers. Drusen characteristics were assessed using the Wisconsin age-related maculopathy grading scale. RESULTS: A delayed macular choriocapillary circulation (DMCC) was defined as a macular choriocapillary filling time greater than 3 standard deviations from the normal mean (greater than 5 seconds). Nine (26%) of the 34 eyes with ARMD were found to have a DMCC. After age adjustment, eyes with DMCC were more likely to have geographic atrophy of the retinal pigment epithelium (p = 0.003) or choroidal neovascularization p = 0.07) than were eyes with a normal MCC. Regional differences in choriocapillary filling times were present in the eyes with a DMCC, including nasal-to-temporal, central-to-peripheral, and inferior-to-superior gradients of progressively less choriocapillary filling delay. The DMCC correlated with the location, number, size, confluence, and fluorescein staining characteristics of the associated drusen. CONCLUSION: DMCC occurs in some eyes with ARMD. This finding may not only assist in defining eyes at risk for progressive disease but may also help to elucidate the pathogenesis of age-related macular degeneration.

Aged↗
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↗
PubMed1995

Accidental Nd:YAG laser injuries to the macula.

PURPOSE: To study the clinical course of accidental, single-focus Nd:YAG laser injuries to the macula. METHODS: We reviewed the clinical course of five eyes (four patients) that sustained macular injuries from a Nd:YAG laser. All patients were examined within 24 hours of injury and were observed without surgical intervention for a mean of 20 months (range, 12 to 32 months). RESULTS: A single full-thickness foveal or parafoveal retinal hole was apparent in all eyes either on initial examination or within two weeks of injury. All macular holes were within 650 microns of the foveal center. The mean final visual acuity was 20/60 (range, 20/25 to 20/400) and was related to the distance between the macular hole and the foveal center. None of the eyes developed either subretinal neovascularization or clinically significant epiretinal membrane formation during the study period. CONCLUSIONS: Despite initial poor visual acuity in patients who had a full-thickness foveal or parafoveal retinal hole, visual acuity improved without treatment when the site of the laser injury was located outside the foveal center.

Adult↗
PubMed1995

Endophthalmitis and orbital cellulitis after radial keratotomy.

PURPOSE: To report the findings concerning three patients with endophthalmitis and one with panophthalmitis and orbital cellulitis radial keratotomy surgery. METHODS: One man referred with panophthalmitis and orbital cellulitis and three women referred with endophthalmitis were treated. RESULTS: After radial keratotomy surgery, during which no microperforation or macroperforation had been reported, a severe Pseudomonas panophthalmitis and orbital cellulitis developed in the man. All vision was lost in that eye. Staphylococcus epidermidis endophthalmitis developed in one woman, Streptococcus pneumoniae endophthalmitis in the second woman and Pseudomonas endophthalmitis in the third woman, after undergoing radial keratotomy procedures during which microperforations occurred. In the latter patient, bilateral simultaneous surgery was performed, but only one eye became infected. The latter two infections resulted in light perception and hand motion vision respectively. In three cases, an initial keratitis was located in the inferior cornea. CONCLUSIONS: Severe bacterial endophthalmitis can occur after radial keratotomy surgery, even in the absence of microperforation during the procedure. Any evidence of postoperative keratitis must be regarded seriously and treated aggressively. Despite use of this approach, the effect on final visual acuity can be devastating.

Adult↗
PubMed1995

Relation of the functional and structural fundus changes after submacular surgery for neovascular age-related macular degeneration.

AIMS: This study was carried out to investigate the precise pattern of visual loss associated with subfoveal choroidal neovascular membranes and the mechanism by which vision is stabilised or improved after submacular surgery. METHODS: Preoperative and postoperative quantitative microperimetry using the scanning laser ophthalmoscope was performed on six eyes of five patients with age-related macular degeneration who underwent subfoveal choroidal neovascular membrane excision. The relation of the microperimetry findings to the preoperative and postoperative fluorescein angiographic features was also assessed. RESULTS: Four of the six eyes had visual improvement by the 6 month postoperative visit; the other two had stabilisation of vision at the preoperative level. Despite these beneficial visual effects, none of the patients fixated within the bed of the excised choroidal neovascular membrane. Subfoveal choroidal membrane excision was associated with a 36% average increase in the absolute scotoma at the 1 month postoperative visit, compared with the preoperative size. The postoperative scotoma appeared to remain stable or decreased slightly in size between the 6 month and 1 year postoperative visits. Recovery of vision was associated with the development of a more stable preferred eccentric fixation locus, of which the distance from the centre of the foveal avascular zone was related to final postoperative vision. Most of the eccentric fixation loci were inferotemporal to the bed of the excised choroidal neovascular membrane. The surgical retinotomy site was associated with persistent postoperative relative scotoma in five of the six cases, but resolved in one patient after 1 year. CONCLUSION: These findings indicate that quantitative scanning laser ophthalmoscope microperimetry may aid in the surgical planning of subfoveal choroidal neovascular membrane excision.

Aged↗
PubMed1994

Keratocyte loss after corneal deepithelialization in primates and rabbits.

PURPOSE: To evaluate the response of stromal keratocytes to central corneal deepithelialization. METHODS: Rabbits and monkeys underwent unilateral mechanical deepithelialization with a blunt instrument and were killed at intervals ranging from 15 minutes to 24 hours after surgery. Two rabbits underwent unilateral deepithelialization under a fluid bath containing corneal preservation medium. Two rabbits were treated unilaterally with corneal preservation medium topically applied every 15 minutes for 16 hours after epithelial removal. Four rabbits underwent linear keratotomy immediately after deepithelialization of the cornea or on normal unoperated corneas and were killed 1 day (two animals) and 14 days (two animals) after surgery. RESULTS: Deepithelialization resulted in severe ultrastructural changes in keratocytes within 30 minutes after surgery. After 24 hours, the number of keratocytes in the anterior stroma underneath the deepithelialized area had decreased significantly in rabbits (P = .0001) and in monkeys (P = .0007) compared with controls. The wound healing was altered and delayed when the epithelium was not present after keratotomy. The use of storage media during and after deepithelialization minimized the early keratocyte changes and appeared to stimulate reepithelialization. CONCLUSIONS: Removal of corneal epithelium causes loss of superficial stromal keratocytes in rabbits and monkeys. Keratocyte death may results from osmotic changes that alter the corneal wound healing response.

Animals↗
PubMed1994

Echographic findings in infectious endophthalmitis.

OBJECTIVE: To correlate the initial echographic findings in eyes with infectious endophthalmitis with the visual prognosis and causative microorganism. DESIGN: A retrospective review of the clinical and standardized ocular echographic findings in eyes with infectious endophthalmitis was performed. SETTING: University-based ophthalmology department. STUDY PARTICIPANTS: One hundred thirty-seven eyes (136 patients) with infectious endophthalmitis that were evaluated by the ocular echography service of the Doheny Eye Institute, Los Angeles, Calif, between January 1, 1981, and December 31, 1992. RESULTS: Four findings on initial echography were associated with poor initial vision: dense vitreous opacities, retinal detachment, macular detachment, and choroidal detachment. Five findings on initial echography correlated with poor final vision: dense vitreous opacities, vitreous membranes, the presence of retinal detachment, the extent of retinal detachment, and the presence of choroidal detachment. Change (decrease) in vision during the follow-up period was associated with the presence of combined vitreous and subhyaloid opacities, retinal detachment, and choroidal detachment. All eyes with initially clear vitreous on ocular echography had either early streptococcal or culture-negative endophthalmitis. Advanced streptococcal endophthalmitis correlated with the most severe vitreous inflammation, vitreous membranes, and the most extensive posterior vitreous detachment, whereas gram-negative endophthalmitis correlated with choroidal detachment on initial echography. Stepwise logistic regression analysis revealed that the presence of choroidal detachment, not gram-negative microorganisms, was the principal predictor of poor visual outcome in these eyes. CONCLUSION: Ocular echography is a useful method in the clinical evaluation and treatment of infectious endophthalmitis, especially in eyes with opaque media.

Adolescent↗