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Biomedical subjects

M Zingirian

Publications and source records attributed to M Zingirian.

At least 19 recordsLinked to original sources
PubMed1997

Long-term restoration of damaged corneal surfaces with autologous cultivated corneal epithelium.

BACKGROUND: Complete loss of the corneal-limbal epithelium leads to re-epithelialisation by bulbar conjunctival cells. Since conjunctival and corneal-limbal epithelial cells represent two different cell lines, this conjunctival healing of the cornea is followed by stromal scarring, decreased visual acuity, and severe discomfort. Unilateral corneal-limbal epithelial defects can be resolved by the transplantation of limbal grafts taken from the uninjured eye. However, this procedure requires a large limbal graft to be taken from the healthy eye, and is not possible for bilateral lesions. We investigated the possibility of restoring the human corneal surface with autologous corneal epithelial sheets generated by serial cultivation of limbal cells. METHODS: Cells were cultivated from a 1 mm2 biopsy sample taken from the limbus of the healthy eye of two patients with severe alkali burns, and thus complete loss of the corneal-limbal surface, of one eye. Normal corneal differentiation was tested with a specific biochemical marker. Autologous cultured corneal sheets were then grafted onto the damaged eyes of the two patients. The patients were followed up at more than 2 years after grafting. FINDINGS: We have shown that corneal progenitor cells are localised in the limbus, that cultured limbal cells generate cohesive sheets of authentic corneal epithelium, and that autologous cultured corneal epithelium restored the corneal surface of two patients with complete loss of the corneal-limbus epithelium. Long-term follow-up showed the stability of regenerated corneal epithelium and the striking improvement in patients' comfort and visual acuity. INTERPRETATION: The cultivation of corneal epithelium might offer an alternative to patients with unilateral lesions and a therapeutic chance to patients with severe bilateral corneal-limbal epithelial defects. Our findings give a new perspective on the treatment of ocular disorders characterised by stem-cell deficiency.

Burns, Chemical↗
PubMed1995

Indocyanine green angiographic findings in central serous chorioretinopathy.

The purpose of this study is to better characterise, on the basis of a large number of cases and follow-up evaluations, choroidal abnormalities recently observed with indocyanine green (ICG) angiography in central serous chorioretinopathy (CSC). Digital ICG videoangiography was performed in 145 patients with active or inactive, acute or chronic CSC. Forty-eight patients were re-examined in a follow-up period of 6-22 months (mean 10 months). Areas of choroidal leakage attributable to hyperpermeability of the choriocapillaris were found in 98.6% of patients in association with active or resolved pigment epithelial leaks and pigment epithelial detachments. Diffusion of ICG into the choroid was characterised by rapid centrifugal spreading of the dye with a wash-out pattern which was particularly evident in areas corresponding to pigment epithelial detachments. In patients with a long-standing disease, when choroidal hyperfluorescence faded, hypofluorescent spots became increasingly evident revealing pigment epithelial alterations not shown by fluorescein angiography. Areas of choroidal leakage remained unchanged in each patient during the follow-up period, even when subretinal exudation resolved either spontaneously or after photocoagulation. In 5 eyes we observed the appearance of leakage points on pre-existing areas of choroidal leakage. Zonal hyperpermeability of the choriocapillaris characterises all the evolutional stages of CSC and seems to be the primary alteration of this disease. When it corresponds to pigment epithelial detachments choriocapillaris hypermeability is probably associated with local hyperperfusion.

Adult↗
PubMed1995

Study of the correlation between average values of optic disc parameters and their measurement variability using stereovideographic digital analysis.

Purpose of our study was to find whether there is a correlation between average values of optic nerve head parameters and their coefficient of variation for repeated measurements. Disc stereo video images were taken with Topcon Imagenet (IS100) and analyzed with the Optic Disc Analysis program. Eleven normal and 9 glaucomatous eyes were selected. A significant correlation was found for horizontal cup/disc ratio (r = -0.037, p = 0.037) and disc area (r = 0.776, p = 0.027) in intra-observer intra-image repeated measurements. Vertical, horizontal and average cup/disc ratios (r = -0.81, r = -0.74, r = -0.78 p < 0.05) showed a significant correlation for intra-observer inter-image repeated measurements. For inter-observer intra-image measurements, a significant correlation was present for average cup/disc ratio (r = -0.64, p = 0.043). Our data show that bidimensional semiquantitative parameters in use for optic nerve head assessment, analyzed by computerized stereovideography, have an intrinsic measurement variability. The variability is significantly related to the value of the measured parameter only when their reference points are determined manually by the operator.

Adult↗
PubMed1992

Photoablative filtration surgery with the excimer laser for primary open-angle glaucoma: a pilot study.

We have performed ab-externo photoablative filtration surgery on 19 patients affected by uncontrolled primary open-angle glaucoma. All cases had wide open angles, were previously treated with argon laser trabeculoplasty and were considered good candidates for trabeculectomy. After topical and peribulbar anesthesia, a limbus-based conjunctival flap was dissected. Photoablation of a rectangular area at the limbus was performed with an argon fluoride excimer laser (193 nm), at 180 mJ x sq cm fluence. The beam was shaped in the appropriate fashion using a custom-made metal mask. Photoablation was continued until aqueous appeared percolating through the juxtacanalicular tissue at the bottom of the crater; a water-tight closure of conjunctiva was then performed. Postoperatively, the anterior chamber reaction was minimal; in no case a flat chamber or choroidal detachment was observed. In 18 of the 19 cases the IOP was significantly lowered, and a filtering bleb developed. Mean preoperative IOP was 26.4 (+/- 7) mmHg. At a median follow-up of 9 months (range 4-15) the IOP is < or = 18 mmHg on no medications in 16 (84%) of the eyes, with a mean value of 13.3 (+/- 6) mmHg. Our short-term results support excimer laser photoablative filtration as a relatively safe and effective procedure for primary open-angle glaucoma.

Aged↗
PubMed1991

[Reversibility of visual field defects in primary open-angle glaucoma].

The course of the glaucomatous visual field seems to be best followed by computerized perimetry which allows threshold evaluation in a great number of locations and statistical analysis of the results. To determine the visual field defect reversibility, 16 patients (27 eyes) affected by uncontrolled open-angle glaucoma underwent visual field analysis before and after prescription of a new medical therapy. To avoid the "learning effect" and to decrease the influence of the heterogeneous component of long-term fluctuation, the visual field examination was repeated within 48 hours whenever a change in sensitivity was detected. In addition a total of 10 normal eyes in 10 patients were tested as a control group. A statistically significant threshold improvement was demonstrable after one week of therapy in 31.7% of the eyes.

Adult↗
PubMed1990

Contribution of manual and computerized perimetry to the differential diagnosis of optic neuropathies.

The contribution given by manual perimetry to differential diagnosis of optic neuropathies is described. The advantages and the disadvantages of automated perimetry in respect to manual perimetry are examined. The programs to use for a more precise diagnosis and according to different pathology are also examined. The problems connected to perimetric interpretation are discussed. The value of global indices in evaluating the visual field as well as the importance of statistical program in comparing more than one test performed are reported. The review stresses the usefulness of automated perimetry in early diagnosis and in the follow up of optic nerve diseases.

Diagnosis, Computer-Assisted↗
PubMed1989

[Automated perimetry and macular diseases].

The macular programs of computerized perimetry are very useful for the functional quantitative assessment of all kinds of maculopathy and for monitoring their clinical evolution. They often help the ophthalmologist in making decisions concerning critical situations.

Computers↗
PubMed1989

[Senile macular degeneration: surgical management and histopathologic features].

Choroidal neovascularization often complicates senile macular degeneration; argon and krypton laser photocoagulation are very useful to stop visual acuity decrease caused by extrafoveal choroidal neovascular membrane (NVM) in a large group of patients. Unfortunately, in a large number of cases, NVM causes haemorrhagic serous detachment, disciform scar and, sometimes, vitreous hemorrhage. In these patients it is impossible to perform laser treatment. A three ports pars-plana vitrectomy has been performed for the treatment of intravitreal hemorrhage in a case of haemorrhagic disciform lesion and in two cases of extensive subretinal haemorrhage secondary to subretinal NVMs. Posterior pole focal retinotomies have been created to remove the NVMs in order to prevent further hemorrhages; an internal tamponade has been performed and the retinotomies closed with endophotocoagulation or endocryo. The specimen of the membranes, stained for light microscopy, have been studied. During the months of follow-up (9 months) no subretinal membrane no retinal detachment developed but fibrosis at the retinotomy sites led to traction on the macula. The functional aim of this surgery is limited to the restoration of a clear vitreous and to a reduction in the diameter of the central scotoma in the cases of a recent subretinal haemorrhage.

Aged↗
PubMed1989

[New occult choroidal vessels in age-related macular degeneration].

We studied the clinical characteristics and the natural course of occult choroidal new vessels (CNV) in 78 eyes with age-related macular degeneration (AMD). Cases were included in 2 groups characterized respectively by ill-defined subretinal ooze (group 1) and serous detachment of the retinal pigment epithelium (RPE) with adjacent areas of mottled pigmentation (group 2). Both these forms of occult CNV showed to have a slower evolution compared to the classic CNV occurring in AMD, but they also led to disciform scar and severe visual loss. Occult CNV of group 2, contrary to those of group 1, were often multifocal and extrafoveal. They had a greater tendency to hemorrhages and a faster and less gradual progression to fibrovascular scarring and visual loss. Fluorescein angiography showed choroidal filling delay in the macular region of 47% of eyes of group 1. A perfusion defect of the macular choroid could be the basis of the low perfusion pressure and the consequent low activity of CNV with the angiographic pattern of ill-defined ooze.

Aged↗
PubMed1989

Perimetric aspects of optic nerve aging.

Perimetry analyzes the efficiency of the entire visual system, but reveals the deterioration of even one of its components. Optic nerve changes, especially those of ischemic nature, which most frequently involve the middle and advanced age, cause typical perimetric findings. Manual kinetic perimetry is particularly indicated for the detection and definition of sectorial and global contractions. Manual static perimetry provides precise information on defect depth. Automated static perimetry quantifies the defect density in a large number of positions and also provides data on the significance of changes recorded during the follow-up. In normal subjects every type of perimetry shows a physiological decay of light sensitivity as a consequence of the aging of the visual system (about 2 dB per decade) and the reduced efficiency of the optic nerve is undoubtedly one of the components of this functional deterioration.

Aging↗
PubMed1988

Pattern dystrophy of the retinal pigment epithelium with vitelliform macular lesion: evolution in ten years.

We report an unusual case of primary dystrophy of the retinal pigment epithelium (RPE) in which a vitelliform macular appearance was associated with reticular hyperpigmentation resembling the pattern dystrophies of the RPE. The entire evolution of the disease was observed and documented step-by-step during a 10-year follow-up. During the progressive change of the lesions morphologic characteristics of butterfly, reticular and macroreticular dystrophy as well as Best's macular dystrophy could be seen. Pathogenetic relationships between all of these dystrophies of the RPE can be supposed.

Adult↗
PubMed1987

Classification of proliferative diabetic retinopathy.

Using panretinal fluorescein angiography, three patterns (A, B, C) of capillary nonperfusion were identified in 308 eyes with proliferative diabetic retinopathy. Statistical analysis showed that there was a significant association with different retinal complications and clinical parameters. Pattern A (83.7%: midperipheral location of capillary nonperfusion) occurs in type I and II diabetes and is associated with early retinal neovascularization and focal macular edema. Pattern B (8.1%: capillary exclusions disseminated on the whole retina) is typical of young type-I diabetics and is complicated by early disc new vessels and ischemic maculopathy. Pattern C (8.1%: capillary nonperfusion confined to the peripheral retina) is observed in type-I diabetic females and associated with multiple, retinal new vessels, without maculopathy. This study also demonstrated that eyes with pattern B retinal ischemia respond less well to laser treatment than eyes with other pattern types. Various pathogenetic factors could lead to these three distinct types of proliferative diabetic retinopathy.

Capillaries↗
PubMed1985

Comparing continuous and stepwise luminance variation in static campimetry using the Grignolo-Tagliasco-Zingirian projection campimeter.

In traditional static perimetry the remarkable precision achieved, resulting mainly from the lack of temporal factors related to latency, largely makes up for the relatively long time required to perform the test. Conversely, the increase in speed of the test and in the information content of the visual field charts counteract the lower precision attained with kinetic perimetry. If the influence of the latency time on responses could be kept at a low value, then adopting a static strategy, based on a continuous rather than discrete target luminance variation for threshold detection, could be justified. For this purpose a luminance variation time sequence designed to reproduce the conditions of the traditional static perimetric test was chosen. The test was performed on the Grignolo-Tagliasco-Zingirian projection campimeter, after comparing its clinical performance with the Goldmann perimeter. These two methods - one based on continuous variation, the other based on discrete target luminance variation - were compared using a 14-subject sample. We conclude that the presentation strategy based on continuous luminance variation can be regarded as a valid alternative to the traditional method.

Adult↗