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Biomedical subjects

M B Abelson

Publications and source records attributed to M B Abelson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Standardized recording of acute corneal disease.

A simple form for standardized recording of acute corneal disease has been designed. It focuses on the discriminative features that are useful in the management of such disorders.

Corneal Diseases↗
PubMed1989

Dynamics of corneal epithelial healing after an alkali burn. A statistical analysis.

A precise definition of epithelial healing kinetics following chemical injury is necessary to aid the investigation of control mechanisms, potential therapeutic intervention and ophthalmic drug toxicity. Wound healing was studied photographically at frequent intervals in rabbits following 1N or 4N alkali burns. Planar wound areas were determined by computerized planimetry and transformed mathematically to curved surface data. The decrease in equivalent wound radius with time was computer-modelled using two linear and three nonlinear regressions. A periodic function was also investigated. Serial photographs showed that intermittent attrition of small areas of the migrating wound edge was a common confounding variable. Although excellent coefficients of determination were found for all models, the addition of nonlinear factors gave a small advantage. A mean lag phase of 3.96 and 6.52 hr occurred after 1N and 4N alkali burns, respectively; wound edge attrition was notably prevalent in early healing. Epithelial healing in the rabbit had a fundamental linear component, with mean epithelial migration rates of 76 and 80 microns/hr after 1N and 4N alkali burns, respectively, and which continued to closure. A quadratic nonlinear component was also suggested. No significant circadian component was detected.

Alkalies↗
PubMed1988

Sustained reduction of intraocular pressure in humans with the calcium channel blocker verapamil.

We investigated the effect of the calcium channel blocker verapamil on intraocular pressure in human volunteers. In the initial trial, 15 subjects with untreated ocular hypertension were tested. After a baseline measurement was obtained with applanation tonometry, a 40-microliter drop of verapamil, 1.25 mg/ml, was instilled in one eye. After 30 minutes, a second reading was taken. In a subsequent trial of 12 untreated ocular hypertensive subjects, the duration of action was determined using the same dose and method of delivery. Results showed that verapamil elicited a mean +/- S.E.M. change in intraocular pressure of -3.8 +/- 0.900 mm Hg in the treated eye, and -1.6 +/- 0.400 mm Hg in the untreated eye. This reduction was statistically different in both eyes (treated eye, P = .0007; untreated eye, P = .005). This decrease in intraocular pressure remained statistically significant when compared to predrug baseline values for up to ten hours.

Administration, Topical↗
PubMed1988

Pharmacologic pupillary modulation in the perioperative period.

The perioperative management of the pupil is essential to the success of anterior segment surgery. A new dilating regimen was tested in 65 cases of cataract extraction and intraocular lens implantation. The alpha-adrenergic agonist, phenylephrine 2.5%, was used after pretreatment with the adrenergic beta-blocker, timolol 0.5%. This treatment successfully dilated the pupil in all but three cases, was maintained by intraoperative epinephrine infusion, and was readily reversed with intraocular acetylcholine. We conclude that this pharmacologic regimen provided a successful and easily reversible mydriasis during surgery.

Acetylcholine↗
PubMed1988

Importance of limbal examination in ocular allergic disease.

We present three adult patients having classic symptoms of ocular allergy with findings confined to the limbus in all eyes. Findings in the cornea and the rest of the bulbar and tarsal conjunctivae were within normal limits. Case 1 had numerous limbal follicles; Case 2 had limbal chemosis 360 degrees; and Case 3 had superior perilimbal conjunctival injection, chemosis, and micropannus formation. Limbal scrapings from all patients revealed abundant eosinophils. There was marked clinical improvement after topical cromolyn sodium 4% treatment. Since the limbus was the only structure involved, the diagnosis of "allergic limbitis" was made. We feel that the limbus is an overlooked structure during ocular examination. As in our three cases, the limbus may be the only area involved in ocular allergy. A careful examination of the limbus may provide important clues for the diagnosis of many ocular inflammatory conditions.

Adult↗
PubMed1988

Levocabastine. Evaluation in the histamine and compound 48/80 models of ocular allergy in humans.

The efficacy of a new antihistamine, levocabastine, in alleviating the ocular allergic reactions induced by both histamine and 48/80 was evaluated in humans. Levocabastine (0.5%) was instilled in one eye of 30 volunteers, and vehicle in the contralateral eye. After 15 minutes, half of the subjects received histamine (25 mg/ml) and half, 48/80 (7.5 mg/ml). The signs and symptoms of allergy were graded clinically after 30 minutes. Compared with a buffer control, levocabastine significantly alleviated itching (P = 0.01), redness (P = 0.0156), and chemosis (P = 0.005) induced by histamine, and itching (P = 0.032) and redness (P = 0.029) induced by 48/80. The results from these pharmacologic models support the clinical use of levocabastine for the treatment of allergic conjunctivitis.

Conjunctivitis, Allergic↗
PubMed1987

Topical arachidonic acid: a model for screening anti-inflammatory agents.

Products of arachidonic acid metabolism, prostaglandins and leukotrienes, play an important role in ocular inflammation. In this study, we investigated the efficacies of the cyclo-oxygenase inhibitors (aspirin, indomethacin, and piroxicam) and the lipoxygenase inhibitors (N-hydroxy-arachidonamide (AH) and phenidone) in reducing ocular inflammation induced by arachidonic acid. Administering arachidonic acid topically (0.50% for rabbits and 0.25% for humans) produced a simple model for evaluating the effects of inhibitors on prostaglandins. In rabbits, aspirin, piroxicam and indomethacin all blocked lid closure and chemosis significantly. In humans, aspirin and indomethacin significantly blocked arachidonic acid-induced conjunctival injection. Neither AH nor phenidone blocked any of the signs of ocular inflammation in rabbits or humans. Further testing of phenidone in the presence of the calcium ionophore, ionomycin, also proved negative. Species specificity in arachidonic acid metabolism may account for the different results in humans and rabbits. This model may be a useful tool for comparing the relative efficacies of topical cyclo-oxygenase inhibitors in treating ocular problems.

Administration, Topical↗
PubMed1984

Tolerance and absence of rebound vasodilation following topical ocular decongestant usage.

Commercial preparations of two topical ophthalmic vasoconstrictors were evaluated for whitening ability, duration of action, tolerance, and rebound vasodilation in 11 normal volunteers. Both 0.02% naphazoline HCI and 0.05% tetrahydrozoline HCI significantly reduced baseline redness after a single use (Part I); however, naphazoline produced significantly more whitening than did tetrahydrozoline. Only naphazoline retained its whitening ability after ten days (Part II). The level of redness remained significantly below baseline for eight hours after a single use of either vasoconstrictor and for six hours after multiple use of naphazoline. The diminished effectiveness of tetrahydrozoline after the ten-day test period may encourage its overuse. Neither vasoconstrictor produced rebound vasodilation after discontinuation of use.

Drug Evaluation↗
PubMed1984

Vernal conjunctivitis in the hyperimmunoglobulinemia E syndrome.

Hyper-IgE syndrome (HIE) appears to be related to an immunoregulatory imbalance characterized by severe deficiency of suppressor T cells, elevated levels of IgE antibodies, and repeated infection of various organ systems. We report the association of HIE syndrome in two definite cases and one probable case of vernal conjunctivitis. This association suggests that T cell-mediated imbalance may be one factor in the pathogenesis of vernal conjunctivitis.

Adolescent↗
PubMed1983

Conjunctival eosinophils in allergic ocular disease.

Tarsal conjunctival scrapings of 317 patients with allergic ocular disease demonstrated that eosinophils were found infrequently in scrapings of patients with mild allergic conditions and were found in only 63% (17/27) of the patients with vernal conjunctivitis. In similar studies of a 12-year-old boy with vernal keratoconjunctivitis, no eosinophils were recovered in his scraping, even though 12 eosinophils were found in five high-power fields of his biopsy specimen. We conclude that eosinophils present in the deep and superficial conjunctival tissues may not be recovered in scrapings; their absence from scrapings should not preclude the diagnosis of allergic ocular disease.

Biopsy↗
PubMed1983

Conjunctival eosinophils in compound 48/80 rabbit model.

Compound 48/80 (N-methyl-p-methoxyphenethylamine formaldehyde condensation product) was used to selectively degranulate mast cells to induce conjunctival eosinophilia in 12 rabbits. Biopsy specimens of bulbar conjunctiva showed that eosinophils were present in all treated eyes. With repeated treatments the number of eosinophils increased; these cells were concentrated in the subepithelial and epithelial zones by day 3. Eosinophils were not found on scrapings of the bulbar conjunctiva in 75% of the rabbits that received single or multiple treatments. We conclude that deep and superficial eosinophil infiltration may be present even when eosinophils are not seen on conjunctival scrapings. Therefore, the absence of eosinophils in scrapings should not rule out the diagnosis of ocular allergy.

Animals↗
PubMed1983

Intracorneal lens implantation.

In previous experiments, we found that a high-water-content hydroxyethyl methacrylate (Permalens) hydrogel implant was not only well tolerated within the rabbit corneal stroma but also would successfully alter the anterior radius of curvature, and thus the refractive state, of the rabbit eye. The same lens material implanted in the cornea of a patient with aphakic bullous keratopathy was tolerated for six months and decreased epithelial edema but did not alter the refractive state. This cornea, containing the intrastromal lens, was obtained at subsequent penetrating keratoplasty and studied by light and transmission electron microscopy. Morphologically, the epithelium and anterior stroma were not edematous, whereas the stroma posterior to the lens remained edematous. Minimal fibroblastic activity was evident at the lens-stroma interface. There were no signs of inflammation, ulceration, or neovascularization.

Aged↗
PubMed1983

Aspirin therapy in vernal conjunctivitis.

Prostaglandin D2 is a secondary mast cell mediator that causes redness, chemosis, mucous discharge, and eosinophil chemotaxis in the eye. It may play an important role in allergic ocular disease. Although histamine is a key mediator of allergic inflammation, antihistamine therapy provides only symptomatic relief. We added aspirin therapy to the treatment regimen of three patients with vernal conjunctivitis. Aspirin acetylates the enzyme cyclooxygenase, thereby preventing the formation of prostaglandin D2. Within two weeks after initiation of aspirin therapy, we noted dramatic improvement in conjunctival and episcleral redness and resolution of keratitis and limbal infiltration. We recommend a trial of oral aspirin as adjunctive therapy for intractable cases of vernal conjunctivitis.

Adolescent↗