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Biomedical subjects

R Brancato

Publications and source records attributed to R Brancato.

At least 127 records · Page 7Linked to original sources
PubMed1991

Study of laser damage to injection-molded diffractive intraocular lenses.

A study of the probability of damage induced in two implant quality injection-molded diffractive intraocular lenses by a commercial Q-switched Nd:YAG laser is presented. The damage thresholds of the diffractive intraocular lenses (0.10 mJ at 10% probability, 0.24 mJ at 50% probability, and 0.90 mJ at 99% probability) did not differ significantly from those of other poly(methyl methacrylate) lenses manufactured with the same technology. These low values (compared to those of other lens types) suggest that care should be taken during laser capsulotomy in eyes implanted with refractive lenses, with special attention given to power losses at the target site due to diffraction effects.

Laser Therapy↗
PubMed1991

Microphthalmos with colobomatous orbital cyst in trisomy 13.

The authors describe a case of trisomy 13 with microphthalmos and colobomatous cyst of the optic nerve and of the chorioretina with orbital extension, in a six-month-old female patient. The colobomatous cyst has been studied by means of computerized axial tomography and ultrasonography in order to follow its evolution. The orbital cyst has not increased in size.

Child, Preschool↗
PubMed1991

New laser modalities for posterior segment treatment.

Laser light is currently used for photocoagulation and photoresection in the posterior segment of the eye. Randomized controlled clinical trials on huge caselists, employing rigorous methodology, have confirmed the efficacy of photocoagulation treatments in numerous retinal pathologies. On the basis of the findings of these trials, precise treatment protocols have been drawn up. Nevertheless, some doubts persist on the indications and exact modalities for laser treatment in certain clinical forms. While the various treatment protocols were being defined, research was focusing on the development of new equipment that would maintain at least the same level of therapeutic efficacy as conventional apparatus while offering advantages in reliability, costs, ease of handling, and working life. An important product of this line of research is the semiconductor diode laser photocoagulator. The new frequency-doubled neodymium:yttrium-aluminum-garnet laser and the continuous wave neodymium:yttrium-aluminum-garnet laser hold promise for contact photocoagulation. Photoresection is acknowledged now as an important means of dealing with vitreoretinal lesions. It provides an adequate solution in selected cases of vitreoretinal pathology and serves as a useful adjunct in conventional surgery.

Choroid Diseases↗
PubMed1991

[Central serous retinopathy (atypical forms)].

In comparison with the typical forms of the central serous chorioretinopathy (CSCR), atypical forms are characterized by an older age, the presence of multiple and bilateral foci, the higher tendency for recurrence and the more accentuated functional damages. They may take the form of DRPE (diffuse retinal pigment epitheliopathy) and of gravitational epitheliopathy. Sedative therapy is justified by the particular psychic background which often accompanies this disease. Photocoagulation must be performed only in very selected cases in order to reduce the damage at the level of the macular photoreceptors.

Adult↗
PubMed1991

Unilateral proliferative diabetic retinopathy and uveitis in the fellow eye: report of a case.

We report the case of a young man with a 20-year history of insulin-dependent diabetes mellitus, proliferative diabetic retinopathy OD, and uveitis OS. None of the common reported causes contributing to this difference between eyes was present. No features of diabetic retinopathy appeared OS after a follow-up of 36 months. This is the first case, to our knowledge, in which uveitis appeared to be associated with an asymmetric presentation in diabetes.

Adult↗
PubMed1991

Histopathology of continuous wave neodymium: yttrium aluminum garnet and diode laser contact transscleral lesions in rabbit ciliary body. A comparative study.

Neodymium: yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation has been shown to be an effective method of lowering intraocular pressure (IOP). Transmission and absorption features of diode laser radiation (810 nm) make these new laser sources suitable for production of transscleral thermal lesions. The transscleral effects on rabbit ciliary body of Nd:YAG and diode laser wavelengths were compared using a CW Nd:YAG laser and a CW Aluminum Gallium Arsenide diode laser. Both lasers were delivered by silica optic fibers, 600 microns in diameter. Eight rabbits were treated by applying the optic fiber 0.5 mm from limbus while increasing energy values from 0.2-2 J. The lesions produced at equal energy values underwent gross and histologic and ultrastructural comparison. Gross examination revealed threshold lesions at 1 J energy for the Nd:YAG laser and 0.8 J for the diode laser. The diode laser produced transscleral thermal lesions of the rabbit ciliary body comparable to those achieved by the Nd:YAG laser. The histologic and ultrastructural study showed that diode laser radiation produced more remarkable damage to the ciliary pigmented structures, causing deep coagulation necrosis of the pigmented epithelium, wide disorganization of the collagen in the stroma, and intravascular coagulation phenomena in the ciliary vessels. Before the introduction of these new laser sources in clinical transscleral procedures, further investigation is needed to determine optimal energy levels.

Animals↗
PubMed1991

Combined vitrectomy, cataract extraction, and posterior chamber intraocular lens implantation in diabetic patients.

Combined extracapsular cataract extraction, pars plana vitrectomy, and posterior chamber intraocular lens implantation was performed in six eyes with proliferative diabetic retinopathy. These eyes all had minimal iris vascular changes and were at reasonably low risk for developing intraoperative and postoperative complications. The surgery must be relatively brief and the endophotocoagulation accurate. Initial visual acuities ranged from light perception to 4/200. With an average follow-up of 9.7 months, final acuities ranged from 4/200 to 20/40.

Aged↗
PubMed1990

Normal endothelial cell density range in childhood.

Specular microscopy of the in vivo corneal endothelium of 214 clinically normal eyes in children ranging from 5 to 14 years of age showed a regular mosaic of hexagonal cells. The cell population density of individuals presented some variation, as it doses in older subjects. Quantitative analysis permitted us to determine the normal range of the endothelial cell count at each age. The mean (+/- SD) value ranged from 3591 +/- 399 cells per square millimeter at age 5 years to 2697 +/- 246 cells per square millimeter for the oldest subjects. Our data show a rapid decrease in cell density up to age 10 years. We estimate from our data a decrease in cell density of 13% between ages 5 and 7 years and an additional decrease of 12% by age 10 years.

Adolescent↗
PubMed1990

Probe placement and energy levels in continuous wave neodymium-YAG contact transscleral cyclophotocoagulation.

To improve the reliability of the technique, contact transscleral cyclophotocoagulation was performed using a continuous wave neodymium-YAG laser. Radiation was delivered via a fiberoptic system to two human eyes destined for enucleation due to choroidal melanoma. Distances from the corneal limbus to where the fiberoptic probe was placed, perpendicular to the conjunctiva, were varied, as were the energy values. Gross, light microscopic, and scanning electron microscopic examinations revealed that contact probe placement at a distance of 1.5 mm from the corneal limbus with an energy setting of 2 J provided optimum cyclophodestructive results. Slight superficial damage to the sclera was detected, but observations indicated no alterations to the adjacent anatomical structures. To obtain lesions to the ciliary processes in living eyes similar to those previously noted in human cadavers, comparatively lower energy values (2 J) were required. To exploit all the mechanisms that may lead to a decrease in intraocular pressure, precise hitting of the aqueous humor secretory structure may prove to be of primary importance.

Choroid Neoplasms↗
PubMed1990

Electroretinographic findings in panretinal photocoagulation for diabetic retinopathy. A randomized study with blue-green argon and red krypton lasers.

A total of 16 patients (16 eyes) with type II diabetes mellitus and proliferative retinopathy were studied electroretinographically before panretinal photocoagulation, during intervals between the treatment sittings, within 36 h of the final treatment and 4 months after its conclusion. Treatments were carried out with blue-green argon (eight eyes) and red krypton (eight eyes) lasers; the type of laser was randomly chosen. The analysis of the results obtained showed a significant and marked reduction in peak amplitudes of both a- and b-waves in photopic and dark-adapted conditions as early as between the multiple treatments. Electroretinograph (ERG) tracks did not change significantly at subsequent checks. Amplitude reductions were higher for scotopic b-waves and in eyes that had the less altered baseline tracks. Implicit times did not change significantly. The type of laser used did not significantly influence ERG evolution.

Aged↗
PubMed1990

Preoperative astigmatic influence on the predictability of intraocular lens power calculation.

The preoperative and postoperative influence of different parameters on the predictability of formulas used for intraocular lens (IOL) power calculation (axial length, corneal dioptric power, IOL malposition, postoperative astigmatism) has been shown by various authors. In this study, we evaluated the preoperative astigmatic influence on the prediction of postoperative refraction in eyes operated on for cataract with IOL implantation. Three hundred and fifty-nine eyes were evaluated after cataract surgery and IOL implantation. We calculated predictive errors of both the Binkhorst and SRK formulas for each eye. Based on the outcome of the predictive errors we divided the eyes into six groups: three of high and three of low predictability. Preoperative astigmatism in these groups was statistically compared (using the Student's t-test). The preoperative astigmatism was always higher in the group with low predictability than in the group with high predictability (P less than .05).

Astigmatism↗
PubMed1990

Comprehensive study of damage to intraocular lenses by single and multiple nanosecond neodymium: YAG laser pulses.

The results of an extensive study of the probability of damage induced in implant quality intraocular lenses (IOLs) by a commercially available nanosecond Nd:YAG photodisruptor are presented. These results were compared with the morphology of damage seen on scanning electron microscopy. The differences in the shape of the damage probability curves derived for the different lens groups demonstrate that a single threshold value does not characterize the threshold for IOL damage. We suggest that a standard method using a clinical photodisruptor be used by all workers to derive these curves for all IOLs in clinical use. The clinical relevance of our findings is emphasized.

Lasers↗
PubMed1990

Photocoagulation scar expansion after laser therapy for choroidal neovascularization in degenerative myopia.

The authors performed a prospective study of 36 eyes affected by pathologic myopia with macular subretinal neovascularization (SRNV) successfully treated with either argon green, dye orange (590 nm), or krypton red lasers. Re-treated eyes were excluded. Evolution of the laser scar was carefully monitored for 12 months. Scar expansion was noted in 35 cases (97%), without a significant loss of visual acuity during the first year after treatment. The scar enlarged more conspicuously during the first 3 months after photocoagulation, with a mean increase of 103% in the first year. Expansion was not related to laser wavelength, patient age, SRNV size, or degree of myopia. Scar enlargement was greatest in the same direction as that of maximal extension of the myopic peripapillary crescent; inspection of the morphologic configuration of the peripapillary crescent before laser treatment may be helpful in evaluating the potential risk of post-laser scar expansion toward the fovea.

Adult↗