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Biomedical subjects

W F March

Publications and source records attributed to W F March.

At least 37 records · Page 2Linked to original sources
PubMed1986

Laser-induced glaucoma in rabbits.

Argon laser energy was applied to the trabecular meshwork of pigmented rabbits in an attempt to develop an animal model of 'glaucoma'. Laser energy was varied to determine the optimal level needed to produce sustained ocular hypertension. An initial response of ocular hypertension followed by hypotension was observed in all of the animals tested. Approximately half of the laser-treated rabbits developed a secondary buphthalmus and sustained ocular hypertension. In these animals outflow facility was decreased by approximately 60%. Histologic examination at 4- and 8 weeks after laser treatment demonstrated a wound-healing response resulting in closure of the intertrabecular spaces and obstruction of outflow to injected carbon particles. Optic nerve cupping and a loss of ganglion cells were also observed. Topical application of L-timolol (0.5%), pilocarpine (2.0%) and forskolin (1.0%) were found to be effective in decreasing intraocular pressure in the laser-treated, hypertensive eye with no significant effect in control non-laser-treated eyes, suggesting that this model can be a useful tool for screening potential antiglaucoma medications.

Animals↗
PubMed1985

Histologic study of a neodymium-YAG laser sclerostomy.

A glaucoma filtering procedure was performed with the YAG laser in an eye to be enucleated for malignant melanoma. Scanning electron microscopic examination shows the extent and position of the incision and the effects of the procedure on the cornea. To our knowledge, this article represents the first report of complete perforation of the sclera in a living human eye with the use of a laser alone.

Cornea↗
PubMed1985

Neodymium-YAG laser sclerostomy in primates.

A one-stage sclerostomy procedure was performed "noninvasively" in four cynomolgus monkeys solely with the neodymium-YAG laser. The neodymium (Nd)-YAG laser was focused, for the most part, a few diopters behind the focus of the helium-neon aiming beam. This enabled optical breakdown to occur entirely within the sclera to produce a perforating micropuncture of the scleral tissue. Two monkeys were treated with higher energy (23 and 24 joules) and two were treated at lower energy levels (12 and 14 joules). An immediate reduction of intraocular pressure in the treated eye was associated with a significant increase in outflow facility. The sclerostomy remained patent for more than 180 days, as determined by tonography and histologic examination. Scanning electron microscopic examination of the cornea revealed no significant damage to the central cornea or to tissue adjacent to the visual axis in any of the treated eyes. However, there was some endothelial cell loss at the site of the laser treatment at the peripheral cornea and in the area immediately posterior to the incision; there was also a focal break in Descemet's membrane.

Animals↗
PubMed1985

Ibuprofen in the treatment of uveitis.

Ibuprofen has gained widespread acceptance for the treatment of rheumatoid arthritis and other inflammatory disorders. We have used ibuprofen in the control of both anterior and posterior uveitis and have found it to be effective in the control of these disorders.

Administration, Oral↗
PubMed1985

Design of new contact lens for YAG laser filtering procedures.

A contact goniolens has been developed specifically for YAG laser filtering procedures both for use in unblocking failed surgical filtering procedures and for performing two-stage or one-stage YAG filtering procedures. The design concentrates the YAG energy and maintains a constant small angle with the cornea.

Contact Lenses↗
PubMed1984

Acute intraocular pressure elevation produced by argon laser trabeculoplasty in the cynomolgus monkey.

The short-term effect of argon laser trabeculoplasty (ALT) was studied in a nonhuman primate model. The ALT treatment produced a consistent intraocular pressure elevation in the treated eye for eight hours. A statistically significant indomethacin-resistant increase in aqueous humor protein concentration was also observed. Morphologic observations using light microscopy and scanning and transmission electron microscopy revealed evidence of a fibrinous material covering the trabecular openings four hours after ALT. Cells and tissue debris appeared to be trapped in this fibrinlike net and may be the cause of the acute rise in IOP. Twenty-eight hours after ALT, the fibrin net was shown to be discontinuous, with fewer cells and less debris present. These acute morphologic alterations were not seen in control eyes or the laser-treated eyes observed later.

Animals↗
PubMed1984

Experimental YAG laser sclerostomy.

A Q-switched neodymium-YAG laser was used to produce a corneoscleral perforation in human cadaver eyes. A through-and-through incision could be created solely with the YAG-laser at peak pulse energies of 16 millijoules (mJ). The minimal total energy required for perforation was 3,312 mJ. However, "optimal" perforation, producing splitting along natural scleral cleavage planes, required 26,676 mJ. Scanning electron microscopy showed the perforations to be clean holes with little debris.

Cornea↗
PubMed1984

Ultrastructural and pharmacologic studies on laser-induced glaucoma in primates and rabbits.

Sustained high intraocular pressure resulting in optic nerve cupping and loss of ganglion cells was produced in five rhesus monkeys and eight pigmented rabbits by applying argon laser energy to the trabecular meshwork. In addition, the rabbits manifested buphthalmus. Flow of carbon particles subsequently injected into the anterior chamber was obstructed at the trabecular meshwork by a wound-healing response that closed the intratrabecular spaces. Besides this sustained high intraocular pressure as a result of late scarring, an acute hypertensive response was seen in all rabbits which may correspond to the acute hypertension seen after laser trabeculoplasty in humans. The acute hypertensive response could be only partially blocked by prostaglandin inhibitors and we believe that prostaglandins are not primarily responsible for this effect. Medications known to lower intraocular pressure were systematically tested in both glaucoma models.

Animals↗
PubMed1982

Duration of effect of pilocarpine gel.

Thirty-five patients participated in a clinical trial of pilocarpine hydrochloride gel applied once daily at 10 PM. Patients tolerated the medication well and there were no untoward side effects. Significant lowering of intraocular pressure was found for 24 hours after administration. The effect 12 hours after administration was greater than 24 hours after administration. Therefore, pilocarpine gel can be endorsed as an effective medication for 24 hours in the vast majority of patients. However, it is incumbent on the prescribing ophthalmologist to measure the IOP at 10 PM at least once after prescribing pilocarpine gel to ensure adequate control of IOP at that time.

Aged↗