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Biomedical subjects

C A Puliafito

Publications and source records attributed to C A Puliafito.

At least 55 records · Page 3Linked to original sources
PubMed1994

Indocyanine green dye-enhanced diode laser photocoagulation of poorly defined subfoveal choroidal neovascularization.

Indocyanine green (ICG) is a dye with an absorption peak (795 to 810 nm) similar to the emission peak of the diode laser (805 nm). Therefore, ICG dye-enhanced diode laser photocoagulation may permit the selective ablation of ICG-retaining choroidal neovascular membranes (CNVM) with relative sparing of the neighboring neurosensory retina. Ten patients with poorly defined subfoveal CNVM were treated with ICG dye-enhanced diode laser photocoagulation and followed for an average of 15 months. One of the 10 patients experienced an immediate significant drop in visual acuity after photocoagulation. Obliteration of the CNVM at the site of laser photocoagulation was confirmed by fluorescein angiography and ICG angiography. Subfoveal chorioretinal scar formation was noted postoperatively in all 10 patients. At last follow up, 9 of these 10 patients had no more than a two-line increase or decrease in visual acuity. These preliminary results suggest that poorly defined subfoveal CNVM can be successfully treated by ICG dye-enhanced diode laser photocoagulation with minimal adverse affect on visual acuity in most cases.

Aged↗
PubMed1993

Holmium:YAG endonasal laser dacryocystorhinostomy.

Previously described techniques of endonasal laser-assisted dacryocystorhinostomy appear to offer several advantages over conventional external dacryocystorhinostomy, including the following: (1) decreased disruption of medial canthal anatomy, (2) enhanced hemostasis, and (3) avoidance of a cutaneous scar. Although good results were achieved, several limitations of early laser-assisted techniques have been noted, including difficulty in removal of the thick bone of the anterior lacrimal crest and inability to obtain specimens of lacrimal sac mucosa for biopsy purposes. In a series of 40 consecutive, primary endonasal dacryocystorhinostomy procedures, we used the holmium:YAG (Ho:YAG) laser for bone removal and endoscopic sinus surgical instrumentation to obtain lacrimal sac biopsy specimens. Intraoperative hemostasis was excellent and medial canthal scarring was avoided in all patients. The overall long-term ostium patency rate in our series was 82%. Several technical modifications adopted in the latter part of our series, including use of a small drill for supplemental bone removal, extensive removal of lacrimal sac mucosa, and use of a double stent, appeared to enhance this success rate.

Adolescent↗
PubMed1993

Picosecond neodymium:yttrium lithium fluoride laser sclerectomy.

The picosecond neodymium:yttrium lithium fluoride laser, a high-power, short-pulse laser that uses low energy per pulse and has a high repetition rate and a highly coherent energy source of 1,053 nm, was used to perform sclerectomies by an ab externo approach in human cadaver eyes. We evaluated laser settings with regard to full-thickness scleral perforation and thermal damage to surrounding tissue. We studied energy per pulse, depth per burst (a present number of spots), spot and line separation of the pattern (spacing between spots of the laser in length [spot separation] and width [line separation]), and total energy required to perforate the sclera. Efficiency was determined by evaluating which settings required the fewest spots and least total energy to perforate the sclera. We studied histologic sections of the sclerectomy sites to determine thermal damage to the surrounding sclera. The picosecond neodymium:yttrium lithium fluoride laser is effective in performing full-thickness sclerectomy with minimal thermal damage to the surrounding tissue. The anterior chamber could be penetrated with an average total energy of 13.3 +/- 0.4 (SEM) J. The sclerectomy size was 545 +/- 11 microns externally and 163 +/- 4 microns internally. Successful sclerectomies were performed with as little as 3 to 5 microns of thermal damage to the surrounding scleral tissue with 250 microJ per pulse.

Cadaver↗
PubMed1993

Holmium laser sclerectomy. Success and complications.

PURPOSE: To investigate the safety and efficacy of holmium YAG laser sclerectomy, a new laser filtration procedure. METHODS: The authors performed holmium YAG laser sclerectomy on 49 eyes of 46 patients (mean follow-up, 12.3 +/- 1.1 months). RESULTS: Mean preoperative intraocular pressure (IOP) was 26.9 +/- 1.3 mmHg; postoperative mean IOP on last follow-up visit was 19.7 +/- 1.6 mmHg. Thirty (61%) of 49 eyes achieved a final IOP of 5 to 22 mmHg, 29 (59%) of 49 had a final IOP of 5 to 19 mmHg, and 21 (43%) of 49 had a final IOP of 5 to 15 mmHg. Sixteen (73%) of 22 eyes treated postoperatively with 5-fluorouracil (5-FU) had a final IOP of 21 mmHg or less. Twenty-seven percent of eyes lost one or more lines of vision, and 36% of eyes gained one or more lines of vision; there was no median change in visual acuity. Complications included suprachoroidal hemorrhage in 7 (14%) of 49 eyes and intraoperative vitreous hemorrhage in 2. Seventeen (35%) of 49 eyes required a second IOP-lowering procedure. CONCLUSION: Holmium YAG laser sclerectomy is an effective means to perform glaucoma filtration surgery. This is a full-thickness filtering procedure, with all of the risks attendant.

Aged↗
PubMed1993

[Spatial confinement of intraocular picoseconds-photodisruption effects].

Laser photodisruption is a routinely performed clinical procedure in intraocular microsurgery of post-cataract membranes, anterior synechies and iridectomies. Damage ranges of several millimeters in diameter, however, limit the use of nanosecond photodisruption close to delicate structures, e.g., in the posterior vitreous. Multiple ps-laser pulses of about 100 microJ pulse energy were used to produce disruptive effects in the anterior lens capsule in rabbit eyes in vivo. Ophthalmoscopical and morphological investigations of these effects were compared with those of minimal ns-disruptions. The direct tissue separation effects as well as the collateral damage zones are about one order of magnitude smaller if ps-laser pulses are used. Minimal sizes of disruptive effects are about 50 microns to 150 microns and 500 microns to 1000 microns for ps- and ns-pulses, respectively. The substantial improvement of spatial confinement of ps-photodisruption enables increased precision of intraocular laser microsurgery and opens up new areas of clinical application in structures like the cornea, anterior chamber angle, and crystalline lens.

Animals↗
PubMed1992

Mid-infrared laser ablation of the cornea: a comparative study.

The ablation thresholds and patterns of collateral damage in cornea produced by Er:YAG (2.94 microns) and Er:YSGG (2.79 microns) lasers were measured. Two different pulse durations, 200 microseconds (normal spiking mode) and 100 ns (Q-switched mode), were used at both wavelengths. In the normal spiking mode, damage zones of 16 +/- 2 microns and 39 +/- 7 microns and ablation thresholds of 250 +/- 20 mJ/cm2 and 420 +/- 35 mJ/cm2 were measured at 2.94 microns and 2.79 microns, respectively. In the Q-switched mode, damage zones of 4 +/- 2 microns and ablation thresholds of 150 +/- 10 mJ/cm2 were found irrespective of the laser used. The similarity between the results using the Er:YAG and Er:YSGG lasers in the Q-switched mode suggest that either laser can be used with equal effectiveness for corneal trephination.

Animals↗
PubMed1992

Contact transscleral Nd:YAG laser cyclophotocoagulation. Midterm results.

BACKGROUND: Early reports of both contact and noncontact transscleral Nd:YAG laser cyclophotocoagulation have been encouraging; however, recent evidence indicates a significant incidence of hypotony, visual loss, and phthisis with the noncontact technique with more than 6 months of follow-up. The authors sought to determine the intermediate term effects of contact transscleral Nd:YAG laser cyclophotocoagulation (CYC). METHODS: The authors followed 116 eyes of 114 patients for a minimum of 1 year after treatment of advanced glaucoma with CYC. RESULTS: The mean preoperative intraocular pressure (IOP) of 35.0 +/- 1.0 mmHg decreased to 18.6 +/- 1.1 mmHg (P less than 0.0001) during the average follow-up of 19.0 +/- 0.6 months (range, 12 to 36 months). Intraocular pressure control of 3 to 25 mmHg was achieved in 72%, 3 to 22 mmHg in 65%, and 3 to 19 mmHg in 56% of eyes. Retreatment was required in 31 of the 116 eyes (27%). Intraocular pressure decreased to less than 3 mmHg in 9 eyes and to 0 mmHg in 6 of these 9 eyes. Nineteen eyes, all with initial visual acuity of counting fingers or worse, progressed to no light perception; 17 of 36 eyes (47%) with visual acuity of 20/200 or better lost 2 or more Snellen lines. CONCLUSION: Midterm results of CYC continue to be encouraging but are tempered by a nearly 10% incidence of hypotony or phthisis and the progression of visual loss.

Adolescent↗
PubMed1992

Digital indocyanine-green angiography in chorioretinal disorders.

The authors performed digital indocyanine-green angiography in 37 patients with chorioretinal disorders. Eighteen patients had choroidal neovascularization, 7 patients had atrophic age-related maculopathy, and 12 patients had uncommon choroidal and retinal disorders. A Topcon indocyanine-green camera was integrated with a digital (1024-line resolution) angiography system. Compared with conventional video or photographic indocyanine-green angiography, this technique offers enhanced image resolution, the possibility of direct qualitative comparison with fluorescein angiography, image archiving, hard-copy generation, and tracing capabilities to plan laser treatment strategies and monitor the adequacy of laser therapy after surgery.

Choroid Diseases↗
PubMed1991

Optical coherence tomography.

A technique called optical coherence tomography (OCT) has been developed for noninvasive cross-sectional imaging in biological systems. OCT uses low-coherence interferometry to produce a two-dimensional image of optical scattering from internal tissue microstructures in a way that is analogous to ultrasonic pulse-echo imaging. OCT has longitudinal and lateral spatial resolutions of a few micrometers and can detect reflected signals as small as approximately 10(-10) of the incident optical power. Tomographic imaging is demonstrated in vitro in the peripapillary area of the retina and in the coronary artery, two clinically relevant examples that are representative of transparent and turbid media, respectively.

Coronary Disease↗
PubMed1991

Cystoid macular edema, retinal detachment, and glaucoma after Nd:YAG laser posterior capsulotomy.

A series of 897 Nd:YAG laser posterior capsulotomies were reviewed for the complications of cystoid macular edema, retinal detachment, new onset of glaucoma, and worsened preexisting glaucoma. After Nd:YAG capsulotomy, 11 patients (1.23%; 95% confidence interval, 0.51% to 1.95%) developed cystoid macular edema and eight patients (0.89%; 95% confidence interval, 0.28% to 1.5%) developed a retinal detachment. The new onset of glaucoma was observed in seven patients (0.78%; 95% confidence interval, 0.20% to 1.36%). Five patients (0.56%; 95% confidence interval, 0.07% to 1.05%) with preexisting glaucoma had persistent worsening of their glaucoma. Most patients with a complication had no identifiable risk factors in common. The numbers of laser pulses and energy delivered were not risk factors. Retinal detachment and cystoid macular edema developed most often many months after capsulotomy and many months to years after the cataract surgery. Patients undergoing Nd:YAG laser capsulotomy therefore require ongoing medical observation to detect and treat these serious complications.

Cataract Extraction↗
PubMed1991

Retinal manifestations of neurofibromatosis. Diagnosis and management.

Five patients presented with vision-threatening retinal tumors and systemic signs of neurofibromatosis, including neurofibromatosis type 1 (four patients) and familial cafe-au-lait spots (one patient). These tumors included large retinal astrocytic hamartomas, multiple retinal capillary hemangiomas, and combined hamartomas of the retina and retinal pigment epithelium, which resulted in rubeotic glaucoma, vitreous hemorrhage, and retinal detachment. Surgical therapy included retinal cryopexy, xenon and argon photocoagulation, scleral buckling, and pars plana vitrectomy with excisional retinal biopsy. Retinal tumors may result in marked visual loss in patients with neurofibromatosis, and vitreoretinal surgery may restore useful vision in some of these patients.

Adolescent↗
PubMed1991

A comparative study of masking fluids for excimer laser phototherapeutic keratectomy.

Several fluids of different viscosity were used to mask deeper tissues while exposing protruding irregularities during therapeutic keratectomy of an irregular anterior corneal surface with the 193-nm argon fluoride excimer laser. A model of an irregular anterior corneal surface was developed in deepithelialized calf eyes using grade 8-0 sandpaper. Therapeutic keratectomy was then performed on 28 eyes at a fluence of 180 mJ/cm2, a repetition rate of 10 Hz, and 500 pulses per eye. Solutions of 0.3% hydroxypropylmethylcellulose 2910 and a 0.1% dextran 70 solution, 1% carboxymethylcellulose sodium solution, or 0.9% saline solution were applied to the corneal surface of 21 eyes. Seven control eyes underwent ablation without the addition of fluid. Scanning electron microscopy demonstrated that corneas treated with dextran 70 had the least surface irregularity, and those treated with carboxymethylcellulose or saline solution had intermediate surface irregularity. Corneas that were ablated without additional fluid had the greatest surface irregularity. The application of a moderately viscous solution during therapeutic excimer laser keratectomy enhances the smoothing effect of surface ablation.

Animals↗
PubMed1991

Energy levels and probe placement in contact transscleral semiconductor diode laser cyclophotocoagulation in human cadaver eyes.

We investigated the effects of semiconductor diode laser contact transscleral cyclophotocoagulation in human cadaver eyes by gross examination, light microscopy, and scanning electron microscopy to determine optimum clinical treatment parameters. Irradiation was performed using a continuous-wave semiconductor diode laser with a fiber-optic probe. At 1.0 to 1.25 mm posterior to the limbus, spots were centered on the pars plicata by gross examination. Exposures of less than 2 J produced no visible damage. A 2- to 3-J exposure produced mild whitening of the ciliary processes, while 4- to 5-J exposures created more intense whitening of the pars plicata. Energies higher than 5 J frequently produced explosive tissue damage. Light microscopy of tissue treated with 1.8 to 6 J at 1.0 to 1.25 mm posterior to the limbus revealed coagulation necrosis of the nonpigmented and pigmented epithelium, with evidence of thermal coagulation of the ciliary stroma and stromal vasculature. Coagulation necrosis was more intense with longer exposure times. We found the optimum parameters for contact transscleral diode laser cyclophotocoagulation in cadaver eyes to be 3 to 4.5 J of energy delivered with the anterior edge of the probe 1.0 to 1.25 mm posterior to the limbus.

Ciliary Body↗
PubMed1991

Holmium-YAG laser surgery on experimental vitreous membranes.

We used a pulsed holmium-YAG laser that emitted in the midinfrared (2.12 microns) to cut experimental vitreous membranes in rabbits via an intraocular fiberoptic delivery system. Thirty-five membranes were treated at distances of 0.5 to 3.8 mm from the retina. All of the membranes that were treated were transected or partially cut. In cases that were treated with the optical fiber encased in a retinal-shielding pick, membranes could be readily transected without retinal injury. Laser vitreous membrane cutting may offer the advantage of near-tractionless membrane segmentation. The combination of a moderately strong target tissue absorption and the ready availability of commercial optical fibers for transmission of 2.12-microns laser energy suggests that the holmium-YAG laser merits further investigation for this application.

Animals↗
PubMed1991

Micron-resolution ranging of cornea anterior chamber by optical reflectometry.

Noncontact, high resolution measurements of anterior eye structures using optical coherence domain reflectometry are described. Distances between intraocular structures are measured by directing a beam of short coherence length light onto the eye and performing an interferometric measurement on the optical group delay of reflected signals. Measurements of corneal thickness, corneal excision depth, and anterior chamber depth are demonstrated in vitro, and the location of tissue boundaries is resolved to within +/- 2 microns. The full-width-half-maximum longitudinal resolution is 10 microns. Sensitivities to reflected signals as small as 10(-10) of the incident power are achieved by heterodyne detection.

Animals↗
PubMed1991

Phthalocyanine photodynamic therapy of experimental iris neovascularization.

Photodynamic therapy using chloroaluminum sulfonated phthalocyanine (CASPc) effectively closed experimental iris neovascularization induced in 6 eyes of cynomolgus monkeys by argon laser retinal vein occlusion. Neovascularization was followed by iris photography, fluorescein angiography, and histopathologic examination by light and electron microscopy. Intravenous injection of CASPc followed by irradiation with 675 nm light damaged endothelial cells and pericytes, leading to exposure of the basal lamina and thrombotic occlusion of the blood vessels. Surrounding tissue appeared preserved without evidence of thermal damage. Resorption of occluded vessels by macrophages began 2 to 3 days after photodynamic therapy. Neovascularization reappeared 7 days after photodynamic therapy, probably representing growth of new vessels. Photodynamic therapy with CASPc may be a useful adjunct in the treatment of iris neovascularization. The model is useful in elucidating the ultrastructural changes observed after photodynamic therapy using phthalocyanines.

Aluminum↗