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Biomedical subjects

J M Parel

Publications and source records attributed to J M Parel.

At least 73 records · Page 4Linked to original sources
PubMed1987

Noncontact trephination of the cornea using a pulsed hydrogen fluoride laser.

We used a pulsed hydrogen fluoride infrared laser and a specially designed axicon lens to perform circular corneal trephinations in ten eye bank eyes. This noncontact system focused each laser pulse into an annulus on the cornea. Corneal perforation was achieved in seven to nine seconds at a repetition rate of 10 Hz, using a laser output energy of 100 mJ per pulse. A trephination, 90% of corneal thickness, 6.5 mm in diameter, was produced with 70 pulses.

Cornea↗
PubMed1987

Internal sclerectomy for glaucoma filtering surgery with an automated trephine.

A technique is described for performing full-thickness glaucoma filtering operation from within the anterior chamber. The procedure utilizes an automated trephine, designated the "trabecuphine," that is capable of simultaneous cutting and irrigation. The trabecuphine is brought into the anterior chamber through a limbal incision 180 degrees away from the planned filter site. The trephine is passed across the anterior chamber, above the iris, and into the angle to perform the sclerotomy. This procedure was performed successfully in 13 eyes of seven cynomolgus monkeys. Complications included two small hyphemas that cleared completely. Other complications such as flat anterior chamber, corneal damage, iridodialysis, conjunctival buttonhole, and cataract formation did not occur. Internal scleral trephination may offer another alternative in the surgical management of patients with intractable glaucoma.

Animals↗
PubMed1987

Accommodation of an endocapsular silicone lens (Phaco-Ersatz) in the nonhuman primate.

In owl monkeys, as a model of endocapsular cataract extraction, the lens material was removed through a small hole in the capsule and was replaced with a silicone polymeric gel. The ability of this endocapsular implant (Phaco-Ersatz) to accommodate was documented when pilocarpine produced an increase in the curvature of the lens surface and a decrease in the anterior chamber depth, just as occurs with the untouched natural lens. Refinements of the surgical technique are required to achieve a controlled degree of filling of the capsular bag and inhibit postoperative epithelial proliferation on the inner capsular surface.

Accommodation, Ocular↗
PubMed1987

An intraoperative intraocular pressure monitor.

An autoclavable instrument based on piezoelectric principles for intraoperative monitoring of the intraocular pressure is presented. Accurate and rapid recordings of intraocular pressure during various surgical techniques are discussed.

Humans↗
PubMed1987

Comparative tonometric measurements of eye bank eyes.

A comparison was made of the accuracy of the Tono-Pen, Pneumatonometer, and Perkins hand-held tonometers by measuring the hydrostatically controlled intracular pressure from 10 to 50 mm Hg in human eye bank eyes. The open stopcock method was used in which the cannulated eye, the hydrostatic pressure controlling column, and a manometer were continuously open to each other. The Pneumatonometer gave accurate results at 50 mm Hg but overestimated the lower intraocular pressures; whereas, the Perkins gave satifactory results at 10 and 20 mm Hg but underestimated higher intraocular pressures. The Tono-Pen displayed the least deviation from the controlled pressure over the entire range studied. Another aspect of this study involved determining that a therapeutic soft contact lens did not have any noticeably adverse effect on the accuracy of the Pneumatonometer and Tono-Pen tonometers.

Contact Lenses, Hydrophilic↗
PubMed1986

Preliminary report on corneal incisions created by a hydrogen fluoride laser.

We created corneal incisions in eye bank eyes with a pulsed hydrogen fluoride infrared laser. This laser was selected because its emission spectrum (2.7 to 3.0 micron) closely corresponds to the absorption peak of water in the infrared region. Short pulses (200 nsec) of hydrogen fluoride laser light focused with a cylindrical lens resulting in radiant exposures of 1.3 J/cm2 at the corneal surface created linear cuts in the cornea with minimal thermal damage adjacent to the incision, suggesting that the pulsed hydrogen fluoride laser may be useful for corneal surgery.

Cornea↗
PubMed1986

Comparison of low- and high-volume irrigation-aspiration systems for extracapsular cataract extraction.

A low-volume irrigation-aspiration system with a 1-mm tip (0.3-mm aspiration port) has been developed for extracapsular cataract extraction. This autoclavable system uses approximately 36% less irrigating fluid during the irrigation and aspiration of cortical material when compared to currently available models. The time required for cortical aspiration is also shortened by 33%. After three years of clinical experience with the low-volume system at the Miami Veterans Administration Medical Center, where almost all extracapsular cataract surgery is now performed with the new system, there have been no adverse effects and subsequent capsulotomy has rarely been necessary.

Aged↗
PubMed1986

Phaco-Ersatz: cataract surgery designed to preserve accommodation.

Phaco-Ersatz represents a new approach to cataract surgery and the correction of aphakia. The procedure involves the removal of the cataractous cortex and nucleus while preserving the lens capsule and its zonular attachments. The empty lens capsule is then refilled with biocompatible and optically suitable clear gel. A physiologic lens is recreated in situ. Experimental work with human cadaver eyes and rabbit and cat eyes in vivo demonstrates this surgical feasibility. A review of the literature reveals contradicting theories regarding the physical laws and lens properties governing accommodation. The accommodative potential of the ersatz lens has not been tested, but it may be speculated that this recreated lens may, in fact, possess some accommodative properties. Experimental investigations in this area represent the logical extension of intraocular lens implant development.

Accommodation, Ocular↗
PubMed1986

Automated light- and dark-adapted perimetry for evaluating retinitis pigmentosa.

Visual fields and dark-adapted thresholds, essential measurements of visual function in patients with retinitis pigmentosa (RP), are usually performed manually. The authors have modified a computerized perimeter to perform automated light- and dark-adapted static perimetry across the visual field of RP patients. Results permit assessment of the level of visual disability in the light and dark and also help define subtypes of RP.

Adaptation, Physiological↗
PubMed1986

Bacterial recovery from automated cataract surgical equipment.

Internal tubing involved in the venting and vacuum mechanism of CooperVision's models 8000-V, 7500, and 6500 units were cultured. Several species of bacteria were found including Staphylococcus epidermidis. The clinical implications of this are discussed as well as a solution to the possibility of intraoperative bacterial contamination from the reported source.

Bacteria↗
PubMed1985

Phacoexcavation as an alternative pars plana technique for lens removal.

The phacoexcavator permits lens removal via the pars plana by mechanical disruption, hydration, and aspiration within the capsule. The instrument is suitable for use with unimanual, bimanual, or three-port methods. In five cases lenses estimated to have 2+ to 3+ nuclear sclerosis were removed successfully in less than three minutes. There were no postoperative complications and the only intraoperative complication was some loss of cortical material in one case. This was recovered and removed during the vitrectomy.

Aged↗
PubMed1984

Vacuum Fixation Ring for radial keratotomy.

The Vacuum Fixation Ring helps stabilize the eye during radial keratotomy. It elevates the intraocular pressure, making the cornea rigid, and improves the control for deep reproducible incisions. The instrument is designed for use with topical anesthesia and a variety of diamond or steel knives.

Cornea↗
PubMed1984

Electric infusion pole adjuster.

A newly developed electric motorized infusion pole stand permits the surgeon to rapidly and accurately alter the rate and pressure of infusion during intraocular surgery.

Humans↗
PubMed1983

Split-frame stereoscopy. A new projection system.

The viewing of projected stereo-slides can be achieved by either prismatic or polarized modalities. Two new projection lenses were designed for polarized split-frame stereoscopy. These lenses fit any of the commonly available (35 mm) projectors.

Ophthalmoscopes↗
PubMed1983

Intraocular diathermy coagulation.

Previously used transvitreal diathermy systems were found to be less than adequate. A new, safer 1.25 MHz medium frequency bipolar instrument is presented, which obviates most of the earlier drawbacks. Coagulation at the retinal surface can be obtained with as little as 0.15 J.

Diathermy↗