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Biomedical subjects

T P O'Brien

Publications and source records attributed to T P O'Brien.

76 records · Page 5Linked to original sources
PubMedDate not supplied

Astigmatism outcomes following spherical photorefractive keratectomy for myopia.

BACKGROUND: Our aim was to examine the change in astigmatism after spherical photorefractive keratectomy (PRK). These effects are essential to optimizing photoastigmatic refractive keratectomy (PARK) to correct astigmatism to within fractions of a diopter. METHODS: We retrospectively reviewed 98 eyes of 178 patients with mild to moderate myopia and cylinder < or = 1.00 diopter (D) treated with spherical PRK (VISX 20/20 STAR excimer laser system); 31 eyes had epithelium removed mechanically with a blade and 67 eyes by a laser-scrape technique. RESULTS: Refractive astigmatism was reduced by greater than 0.25 D in 27 eyes (28%); refractive astigmatism was induced by greater than 0.25 D in 31 eyes (32%); the average vector-corrected difference between an eye's astigmatism before and after surgery was 0.01 +/- 0.52 D (P = .85). Eyes with high topographic astigmatism but low refractive cylinder before PRK showed an average of 0.07 +/- -0.60 D change in refractive cylinder after PRK. Refractive astigmatism of more than 0.25 D was induced in 16 eyes (44%) that received manual removal of epithelium versus 15 eyes (24%) that received laser removal of epithelium (odds ratio 2.51, P < .01). CONCLUSIONS: When using PRK for astigmatism correction, refractive cylinder before surgery rather than topographic astigmatism may be the most appropriate method for targeting the astigmatism correction, especially when the two values are discordant. An unpredictable mild increase or decrease in astigmatism may be expected.

Adult↗
PubMedDate not supplied

Perioperative microbiologic profile of the conjunctiva in photorefractive keratectomy.

PURPOSE: Therapeutic soft contact lenses are used commonly as an adjunctive treatment after photorefractive keratectomy (PRK) to decrease postoperative pain caused by the movement of lids over the corneal epithelial defect and to facilitate epithelial healing. We assessed the microbiological profile of the conjunctiva of patients undergoing PRK for myopia, before and after the concurrent use of a therapeutic soft contact lens, and compared the effect on ocular bacterial colonization of prophylactic administration of topical tobramycin 0.3% versus ofloxacin 0.3%. METHODS: Forty-three consecutive eyes from 37 patients underwent PRK for myopia or myopic astigmatism. Eyes were assigned randomly to prophylactic antibacterial treatment with either topical ofloxacin 0.3% or tobramycin 0.3%, applied prior to surgery and three times daily after surgery until therapeutic soft contact lens removal. Material from the conjunctival sac was obtained for bacteriologic cultures prior to surgery. Clinical evaluation of all eyes was conducted prospectively. Three days after PRK, the therapeutic soft contact lenses were removed and cultured. Cultures from the conjunctival sac were then repeated. RESULTS: No statistically significant differences were observed in culture positivity between the two groups of eyes, in spite of some positive preoperative and postoperative cultures. Only one out of 43 eyes (assigned to the ofloxacin group) developed a peripheral corneal infiltrate. The corneal infiltrate healed completely without sequelae using antibiotic and corticosteroid therapy. CONCLUSIONS: The use of therapeutic soft contact lenses after PRK with either topical tobramycin 0.3% or ofloxacin 0.3% were well tolerated. However, perioperative positive conjunctival cultures were relatively frequent and prophylactic antibiotics should be used in the setting of an epithelial defect and therapeutic soft contact lens following PRK.

Adult↗
PubMedDate not supplied

Basic ocular pharmacotherapy.

1. There are certain unique features of pharmacotherapy as it relates to the eye. One is that we have the ability to apply a drug directly to the surface of the eye in the form of eyedrops. This has important ramifications in terms of pharmacokinetics, the distribution of drug throughout the ocular tissues. 2. Ocular pharmacokinetics is the study of the distribution of a drug over time. One of the principles of pharmacotherapy is that we want to maximize the amount of drug that reaches the site of action in a sufficient concentration to cause a beneficial therapeutic effect. 3. Ophthalmic nurses play an important role in patient education, because they spend time talking to patients about the proper way to use drugs.

Eye Diseases↗