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Biomedical subjects

A L Robin

Publications and source records attributed to A L Robin.

At least 91 records · Page 5Linked to original sources
PubMed1986

The effect of neodymium: YAG laser capsulotomy on aqueous humor dynamics in the monkey eye.

The creation of a posterior capsulotomy utilizing a neodymium:YAG (Nd:YAG) laser is often followed by an increase in the intraocular pressure (IOP). In order to study the cause of this pressure rise, six eyes of three cynomolgus monkeys underwent extracapsular cataract extraction followed 2 to 3 months later by Nd:YAG laser capsulotomy. Eyes were evaluated clinically and examined histopathologically at 1 hour, 3 hours, 1 day, 3 days, 1 week, and 1 month after laser treatment. Although IOP did not increase after laser capsulotomy, outflow facility was decreased 80% from baseline levels at 3 hours, at 3 hours, 1 day, and 3 days. After laser treatment, the anterior chamber and meshwork contained fibrin, lens material, inflammatory cells, pigmented macrophages, erythrocytes, and free pigment. Most of these elements had cleared the meshwork by 1 month.

Animals↗
PubMed1985

A comparison of Peritest automated perimetry and Goldmann perimetry.

Both Peritest perimetry and Goldmann visual field testing were performed on three groups of eyes. Eighty-one eyes had glaucoma with elevated intraocular pressures and abnormal visual fields determined by Goldmann perimetry. There were 47 eyes with suspected glaucoma, based on elevated IOPs and normal Goldmann visual fields. Nineteen eyes were normal. All visual fields were evaluated in masked fashion, and the results were compared. The Peritest had a high sensitivity in both glaucomatous (98.8%) and normal (94.7%) eyes. One half of the eyes with suspected glaucoma had abnormal Peritest results but normal Goldmann visual fields. These eyes were examined prospectively with color stereo discs and monochromatic nerve fiber layer photographs. One half of the eyes with suspected glaucoma and abnormal Peritest results also had photographic evidence suggesting optic nerve damage. Thus, early field defects detected by the Peritest perimeter in eyes with suspected glaucoma are likely to be representative of glaucomatous damage.

Adult↗
PubMed1985

Q-switched neodymium-YAG laser angle surgery in open-angle glaucoma.

In a short-term pilot study, we evaluated Q-switched neodymium-YAG laser angle surgery in 25 eyes from 22 patients with medically uncontrolled open-angle glaucoma. All eyes had unacceptable intraocular pressures (IOPs), despite maximum tolerated medical therapy, argon laser trabeculoplasty, and prior intraocular filtration surgery (eight eyes). Using a pulse energy of 10 millijoules, ten spots were placed approximately 4 degrees apart in the mid-trabecular meshwork using an Nd-YAG laser (Coherent 9900). The mean preoperative and final postoperative IOPs were 30 +/- 6 mm Hg and 21 +/- 8 mm Hg, respectively. The mean follow-up time was five (+/- 3) months (range, two to 14 months). The final postoperative IOP was less than 22 mm Hg in 17 eyes (68%). Holes within the trabecular meshwork were visible in 14 eyes, and laser therapy was associated with the liberation of debris into the anterior chamber in all eyes. Complications included transient postoperative IOP elevation (eight eyes), angle bleeding (six eyes), and posterior displacement of the iris root (four eyes).

Adolescent↗
PubMed1985

Early complications following Q-switched neodymium: YAG laser posterior capsulotomy.

A prospective evaluation was conducted of Q-switched neodymium: YAG laser capsulotomy in 53 eyes followed for one postoperative month. The first 31 eyes were seen at two-hour intervals for the first eight hours, and the remaining eyes were checked only at the second postoperative hour during that day. Eighty-nine percent of eyes required a pulse setting of less than 1.7 mJ to successfully penetrate the posterior capsule. Visual acuity was improved in 91% of eyes. A transient immediate postoperative intraocular pressure (IOP) elevation was seen in over 75% of treated eyes, and one-third had an IOP elevation greater than 10 mmHg over the preoperative IOP. This elevation was most common in glaucomatous eyes and occurred in almost one-half of the treated eyes by the second postoperative hour. This IOP change did not correlate with the degree of inflammation, bleeding, anterior chamber debris, or total energy delivered. Minimal iris bleeding occurred in 9% of treated eyes and was associated with iridocapsular adhesions. Eighty-one percent of eyes with posterior chamber implants developed some degree of lens damage.

Adult↗
PubMed1985

Neodymium:YAG laser iridotomy in the cynomolgus monkey.

The histologic effects of various Neodymium:YAG laser energy levels were evaluated after iridotomy formation in cynomolgus monkey eyes. Scanning election microscopy of the corneal endothelium above the treated areas revealed no significant cell loss or pleomorphism when compared to the adjacent untreated areas. Light and phase contrast microscopy demonstrated closure of the iridotomies in most cases by a bridge of iris pigment epithelium. In several specimens, stromal tissue and pigment laden cells were present over the attenuated iris pigment epithelium. There were four lens opacities with rupture of the anterior lens capsule and anterior epithelial cell hyperplasia in one. No damage was apparent in the trabecular meshwork or retina with light microscopy or fluorescein angiography.

Animals↗
PubMed1984

Flurbiprofen pretreatment in argon laser trabeculoplasty for primary open-angle glaucoma.

We examined the influence of topically administered flurbiprofen sodium 0.03%, a potent prostaglandin inhibitor, on the inflammatory response and intraocular pressure following argon laser trabeculoplasty. Our investigation included one eye of each of 118 patients with primary open-angle glaucoma in whom laser trabeculoplasty was indicated. Sixty-three patients received flurbiprofen and 55 received a vehicle during the two-hour period immediately preceding laser therapy and for one week postoperatively. No significant differences in postoperative IOPs were noted between groups. However, when we considered conjunctival erythema at 24 hours or control of inflammation at the termination of the investigation, the eyes receiving flurbiprofen had less inflammation than did the vehicle-treated eyes.

Aged↗
PubMed1984

Evaluation of nerve fiber layer assessment.

More than 1,400 eyes with either ocular hypertension glaucomatous visual field loss, or normal pressures and fields (controls) were studied prospectively in standardized, masked fashion. The appearance of the nerve fiber layer was evaluated independently from red-free photographs with the discs blocked-out by two observers. The vast majority of photographs could be evaluated, the proportion varying with the observer and with the age and clinical status of the subject. Sensitivity (proportion of glaucomatous eyes with nerve fiber defects) and specificity (proportion of normal control eyes without defects) averaged 80% to 94%, varying with the observer and with the age, race, and severity of field loss. In two thirds of presumed false-positive eyes, but only 5% of true-positive eyes, the abnormalities were limited to focal slitlike defects. The prevalence of nerve fiber defects in eyes with elevated pressure and normal visual fields was similar to that in control eyes, approximately 10%. However, the proportion of eyes in which these defects included diffuse loss was considerably higher among the hypertensive eyes.

Adult↗
PubMed1984

Argon laser trabeculoplasty in younger patients with primary open-angle glaucoma.

We conducted a retrospective comparison of the effectiveness of argon laser trabeculoplasty in controlling increased intraocular pressure in two different age groups treated for medically uncontrolled primary open-angle glaucoma. Of 15 eyes of patients less than 40 years old who had primary open-angle glaucoma, nine (60%) had uncontrolled intraocular pressures postoperatively and needed filtering surgery within two years of argon laser trabeculoplasty. Only two of 29 (7%) eyes in older patients had unacceptably high intraocular pressures during a mean (+/- 1 S.D.) follow-up period of 17 +/- 5 months. Older eyes had greater decreases in intraocular pressure (12 +/- 6 mm Hg) than younger eyes (5 +/- 6 mm Hg) after laser treatment. Failure in young eyes appeared to correlate with a high preoperative intraocular pressure. Thus, argon laser trabeculoplasty is not a reliably effective form of therapy for younger patients with primary open-angle glaucoma.

Adolescent↗
PubMed1984

A comparison of neodymium: YAG and argon laser iridotomies.

A prospective short-term clinical study evaluated argon and Q-switched neodymium:YAG laser iridotomies in 40 eyes of 20 patients with primary chronic angle-closure glaucoma. All patients had bilateral iridotomies with one eye randomly assigned to argon laser and the fellow eye to neodymium:YAG laser therapy. In all eyes a patent iridotomy was created in one treatment session. A mean of 12 +/- 11 and 0.033 +/- 0.025 J were needed for iridotomy formation in argon and neodymium:YAG treated eyes respectively. No neodymium:YAG and six (30%) argon iridotomies had marked closure requiring retreatment. Immediate postoperative intraocular pressure elevation greater than 10 mmHg was seen in seven (35%) argon and six (30%) neodymium:YAG-treated eyes. Nine (45%) eyes treated with the neodymium:YAG laser had bleeding from the iridotomy site. No acute lens damage was found in the neodymium:YAG eyes while seven (35%) lenses in the argon group had focal opacities. Seven (35%) neodymium:YAG and five (25%) argon treated eyes had focal nonprogressive corneal opacities above the iridotomy site. Specular microscopy showed a significant central corneal endothelial loss in argon laser treated eyes. No eyes had detectable retinal damage.

Adult↗
PubMed1984

Nonsteroidal anti-inflammatory agents after argon laser trabeculoplasty. A trial with flurbiprofen and indomethacin.

Seventy glaucomatous eyes received argon laser trabeculoplasty (ALT) to 180 degrees of the trabecular meshwork. Thirty-six eyes were treated with topical .03% sodium flurbiprofen, a nonsteroidal anti-inflammatory agent; 34 eyes received placebo. Eighteen eyes received ALT to 360 degrees of the meshwork; nine of these eyes were treated with topical 1% indomethacin and nine eyes received placebo. Eyes treated with flurbiprofen and indomethacin showed significantly less conjunctival injection following ALT. However, these agents did not significantly alter the anterior chamber reaction after laser therapy compared to placebo. Flurbiprofen-treated eyes showed a significantly smaller percent (32.6%) decrease in intraocular pressure (IOP) one day after ALT as compared to eyes receiving placebo (43.8%). In addition, a higher percentage of placebo treated eyes had a fall in IOP of at least 10 mmHg up to five weeks after ALT. Within the indomethacin protocol, the percentage change in IOP was comparable for both indomethacin and placebo treated eyes. Mild ocular symptoms (itching, burning, foreign-body sensation) developed in 77.8% of flurbiprofen-treated eyes, in 55.6% of indomethacin-treated eyes, and in 20.9% of eyes receiving placebo.

Adult↗
PubMed1984

The Q-switched ruby laser in glaucoma.

A pilot study evaluated the safety and effectiveness of a Q-switched ruby laser in the treatment of both pupillary-block (10 eyes) and open-angle glaucoma (4 eyes). All patients had either poor visual acuity or had previously failed with conventional surgery. We created a patent iridotomy in all eyes, with one pulse in eight. Three of the four eyes with open-angle glaucoma had an intraocular pressure decrease of at least 15 mmHg after angle treatment. The major complication of Q-switched ruby iridotomy was blood and pigment within the anterior chamber obscuring the view of the iris. There were no apparent complications noted with Q-switched ruby angle treatment. The potential advantages, complications, and future uses of Q-switched lasers in glaucoma are discussed.

Adolescent↗
PubMed1984

Use of the neodymium:YAG laser to create iridotomies in monkeys and humans.

In a prospective study the Nd:YAG laser was used to create iridotomies in cynomolgus monkeys, using various levels of energy and pulse-trains of 1 to 9. Although no change occurred in the endothelial cell count of the cornea, opacities of the corneal endothelium and lens did occur. In addition, one eye showed rupture of the anterior lens capsule immediately behind the iridotomy. Most of the iridotomies in these animals closed within 3 to 4 weeks. Attenuated pigment epithelium bridged the gap within 9 days and in many sections it appeared that the iridotomies closed by fibrous contraction or early stromal regeneration. A prospective short-term clinical study evaluated argon and Q-Nd:YAG laser iridotomies in 42 eyes of 21 patients with primary chronic angle-closure glaucoma. In each patient one eye was randomly treated with an argon laser iridotomy and the fellow eye with a Nd:YAG laser iridotomy. In every case a patent iridotomy was created in one session. A mean of 12 +/- 11 and 0.033 +/- 0.025 Joules was required to complete an iridotomy with the argon and Nd:YAG lasers, respectively. Thirty percent of the argon iridotomies became sufficiently closed with pigment to require retreatment; whereas none of the Nd:YAG iridotomies closed. A postoperative rise in IOP greater than 10 mm Hg was seen in 38% argon- and 29% Nd:YAG-treated eyes. Although bleeding around the iridotomy occurred in 48% of eyes, in no case was this of significant consequence. No acute lens damage was observed in the Nd:YAG-treated human eyes, while 43% of lenses in the argon group had focal opacities. Thirty-three percent of Nd:YAG- and 24% of argon-treated eyes had focal, nonprogressive corneal opacities above the iridotomy. Specular microscopy showed a significant central corneal epithelial cell loss in argon laser eyes only. The potential of creating a laser iridotomy with a single burst of energy is extremely attractive and worthy of further investigation.

Animals↗
PubMed1983

Argon laser trabeculoplasty in secondary forms of open-angle glaucoma.

A pilot study evaluated both the safety and the effect on intraocular pressure control of argon laser trabeculoplasty (ALT) in eyes with secondary forms of open-angle glaucoma. All patients included in this study had poor IOP control and were considered surgical candidates. The ALT was considered successful if IOP control was sufficient to avoid conventional filtration surgery. Fifty-five eyes of 46 patients were treated. The mean follow-up was 8 +/- 4 months. The mean IOP decrease was 13 +/- 9 mm Hg. The ALT caused serious complications in none of the 55 eyes and seemed most effective in treating pigmentary, pseudoexfoliation, and angle-closure glaucoma present after iridotomy. The ALT had minimal therapeutic effect in eyes with uveitic, angle-recession, and congenital glaucoma.

Argon↗