PubMed Health⌕ Search

Biomedical subjects

M A Johnstone

Publications and source records attributed to M A Johnstone.

16 recordsLinked to original sources
PubMed2001

Glaucoma surgery treatment patterns of ASCRS members--2000 survey.

A survey of glaucoma surgery parameters was mailed to all the United States members of the American Society of Cataract and Refractive Surgery in 1999 and 2000. Of the 5659 surveys mailed, 725 (13%) were returned. The survey assessed parameters used in glaucoma surgical treatment. Preferred surgery treatment patterns were cross-tabulated with fellowship training in glaucoma (9.3%) and geographic location. This report summarizes current practice styles and patterns of comprehensive ophthalmologists in the United States as derived from the survey.

Cross-Sectional Studies↗
PubMed1997

Hypertrichosis and increased pigmentation of eyelashes and adjacent hair in the region of the ipsilateral eyelids of patients treated with unilateral topical latanoprost.

PURPOSE: To describe hypertrichosis and increased pigmentation of eyelashes associated with topical latanoprost usage. METHODS: Patients using unilateral topical latanoprost for glaucoma were examined for evidence of hypertrichosis and pigmentation of eyelashes and adjacent hair in the latanoprost-treated eye compared with the nontreated control eye. RESULTS: In 43 patients receiving unilateral topical latanoprost, hypertrichosis involved ipsilateral terminal eyelashes and regional intermediate hairs of the upper and lower eyelid as well as vellus hair of the lower eyelid skin. Differences in hair appearance between the latanoprost-treated eye and the nontreated control eye included increased number, length, thickness, curvature, and pigmentation. CONCLUSIONS: Latanoprost-treated eyes develop hypertrichosis and increased pigmentation in the region of treatment. Patients may benefit from being made aware of this side effect.

Administration, Topical↗
PubMed1993

A releasable scleral-flap tamponade suture for guarded filtration surgery.

Postoperative complications of filtering surgery are generally associated with overfiltration. We describe a technique that employs an externalized releasable suture in partial-thickness filtering surgery. This suture acts as a tamponade on the anterior surface of the scleral flap, assisting in maintenance of anterior-chamber depth during the early postoperative period. After using this technique, anterior-chamber depths preoperatively and 1 day after surgery were compared in 35 phakic patients. A mean (+/- SD) decrease in anterior chamber depth of 4.6% +/- 12% was found on the first postoperative day. One patient had iridocorneal apposition. The mean intraocular pressure 1 day after surgery was 7.0 +/- 7.0 mm Hg, with one patent having an intraocular pressure of 28 mm Hg. This "tamponade suture" appears to be useful in maintaining the anterior chamber depth in the early postoperative period while permitting satisfactory filtration.

Adult↗
PubMed1990

Evaluation of ocular hypersensitivity to dipivalyl epinephrine by component eye-drop testing.

Dipivalyl epinephrine (dipivefrin) is a prodrug of epinephrine used for topical glaucoma therapy. Local side effects have been noted in approximately 20% of patients treated and include conjunctival hyperemia, foreign body sensation, and follicular conjunctivitis. We studied five patients with adverse local reactions to dipivefrin (Propine) eye drops. Propine contains the following: dipivefrin, 0.1%; mannitol, 1.89%; sodium metabisulfite, 0.075%; disodium edetate, 0.0127%; and benzalkonium chloride, 0.004%. Since the reactions could conceivably have been caused by an ingredient other than dipivefrin, we first patch tested the patients with the maximum recommended concentration of each ingredient. All patch tests were negative. Sterile ophthalmic solutions of each individual component at the concentrations used in the commercial product were then prepared. In a double-blinded study, the patients applied two drops of each preparation, twice daily for 1 week, with a 1-week, drug-free period between trials. Dipivefrin alone reproduced each patient's initial Propine-induced conjunctivitis; symptoms occurred unilaterally in one patient and bilaterally in the other four patients. This study indicates that testing with single component eye drops can identify the provocative component in ocular drug hypersensitivity and that these reactions can be unilateral.

Adult↗
PubMed1983

Surgical management of chronic glaucoma in aphakia.

The surgical management of glaucoma in aphakia has been limited by poor success in the control of intraocular pressure and serious postoperative complications that threaten vision. A consecutive series of trabeculectomy filtering procedures in aphakic eyes with a mean preoperative intraocular pressure of 38 mmHg was followed for an average of 26 months and revealed a 62% control of intraocular pressure at 21 mmHg or less. Five additional patients (24%) had pressures lower than 21 mmHg following digital massage. The complication of decreased visual acuity following surgery was significant but not directly related to the surgical procedure. Another patient population with glaucoma and aphakia with a mean preoperative pressure of 25 mmHg was treated with laser trabeculoplasty. In 12 of 15 patients (80%) intraocular pressure was lower than 22 mmHg for an average of eight months and did not require glaucoma surgery. There were no significant complications following this therapy and all patients retained preoperative level of visual acuity. In aphakic patients who have uncontrolled glaucoma on maximal medical therapy, surgery is indicated. We recommend the following approach to surgical management: (1) Laser treatment to the trabecular meshwork if the angle is open; (2) if this fails, or the angle is extensively closed, a trabeculectomy filtering procedure is suggested; (3) cyclocryotherapy has been effective in controlling pressure but the unpredictable loss of vision has prompted caution in seeing eyes; (4) cyclodialysis; and (5) transpupillary or transscleral treatment of the ciliary processes are additional modes of therapy. Improved results of surgical treatment for glaucoma and aphakia have been encouraging and should be used when maximal medical therapy is ineffective.

Adult↗
PubMed1979

Pressure-dependent changes in nuclei and the process origins of the endothelial cells lining Schlemm's canal.

Monkeys eyes were fixed with glutaraldehyde in vivo at positive intraocular pressure of 35 or 25 mm Hg and compared with eyes fixed without a positive pressure gradient, with the use of light microscopy and transmission and scanning electron microscopy. The entire endothelial lining of the inner wall of Schlemm's canal ballooned or distended toward the external wall of the canal at positive intraocular pressure. Characteristic nuclear shapes were identified and appeared to result from the increased pressure forcing the lining away from the meshwork opposed by a restraining or anchoring effect of cytoplasmic processes attached to the subendothelial cells and trabecular meshwork. Without positive intraocular pressure endothelial cell nuclei were rounded, with many folds and notches in the nuclear membrane and were not deformed by their cytoplasmic processes. These findings suggest that the cells may be capable of elastic recoil or contraction.

Animals↗