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Biomedical subjects

S W Liou

Publications and source records attributed to S W Liou.

6 recordsLinked to original sources
PubMed2001

Myopia and contrast sensitivity function.

PURPOSE: to measure the contrast sensitivity function of varying degrees of myopia with two types of optical correction (spectacle lens and contact lens). METHODS: One hundred and five myopic eyes and twenty-eight emmetropic eyes were collected. The myopic group included 105 eyes corrected with spectacle lenses and 71 eyes of them corrected with contact lenses, too; all had corrected vision acuity of 20/20 or better. The myopic eyes were divided into four groups: group 1 (-1D to -3D), low myopia; group 2 (-3.25D to -6D), medium myopia; group 3 (-6.25D to -12D), high myopia; and group 4 (> -12D), severe myopia. Spatial contrast sensitivity was measured using the OPTEC 2000 Contrast Sensitivity System. RESULTS: In groups 1 and 2, no statistically significant difference was found between myopes and emmetropes. In group 3, statistically significant loss of contrast sensitivity at higher spatial frequencies was found for myopic subjects corrected with spectacle lens, but not for myopes corrected with contact lens. In group 4, myopic subjects corrected with spectacle lenses showed significantly reduced contrast sensitivity function at all spatial frequencies; subjects corrected with contact lenses showed statistical sensitivity losses at 6, 12, 18 cycle/degree spatial frequencies. CONCLUSIONS: 1. We may suppose that low and medium myopes (groups 1 and 2), who showed normal contrast sensitivity functions, had no retinal dysfunction. 2. For high myopes, contact lens correction could reduce optical defocus and improve contrast sensitivity function in high spatial frequencies. 3. As retinal function disturbances occurred in severe myopes, the diminished contrast sensitivity was not fully compensated by contact lens correction. 4. Loss of contrast sensitivity might be interpreted as evidence for early retinal function disruption before retinal pathological events occur in severe myopes.

Adult↗
PubMed2001

Maintenance of mydriasis with one bolus of epinephrine injection during phacoemulsification.

Surgically-induced miosis commonly occurs during cataract extraction surgery, complicating removal of lens cortex and placement of a posterior chamber intraocular lens. To maintain intraoperative mydriasis, one bolus of epinephrine injection was used in our study. The pupillary response to various doses of intracameral epinephrine (0.1 ml of 1:25,000, 1:50,000, 1:100,000, 1:200,000, 1:400,000) was assessed in 60 consecutive patients. The pupil size was measured just prior to the incision, one min after epinephrine injection, after phacoemulsification and after irrigation/aspiration. There was no significant difference among the mean mydriatic responses to the epinephrine concentrations we tested. The 1:400,000 concentration appeared to be as effective as 1:25,000, but two cases of the 1:400,000 group failed to maintain the pupil diameter after irrigation/aspiration. In addition, we found that blood pressure did not elevate after injection of any concentration of epinephrine. We concluded that one bolus of an extremely dilute concentration of epinephrine (i.e., 1:400,000) injection might be effective in maintaining mydriasis during cataract surgery without systemic side effects.

Aged↗
PubMed2000

Impression cytology of pterygium.

The purpose of this study was to study the morphology and cytokeratin expression in the epithelia of pterygia. Impression cytology and immunohistochemical staining with antikeratin antibodies were performed in 32 eyes of 16 patients with pterygia. TUNEL stain and electron microscopy were also performed in surgical specimens ofpterygium. Squamous metaplasia-like epithelial cells were found in all specimens of impression cytology, especially in the head part. These specimens had positive immunostaining by antipancytokeratin antibodies, but not by anti-K12 AK2 mAb. Goblet cells were found around the area of these abnormal epithelial cells. TUNEL-positive cells were found in the epithelia of the pterygial head, but not in the body of pterygia and normal conjunctiva. The expressional patterns of keratin by these epithelial cells ofpterygia are consistent with the notion that they are derived from conjunctival epithelium and mimic the process of squamous metaplasia.

Aged↗
PubMed1998

The effect of intracameral adrenaline infusion on pupil size, pulse rate, and blood pressure during phacoemulsification.

Pupillary constriction during phacoemulsification (phaco) and irrigation/aspiration (I/A) is found to be the major cause of iris damage, incomplete cortex removal, posterior capsule rupture, vitreous loss and even posterior lens material dislocation. Cataract surgery is performed more easily if mydriasis can be maintained. Irrigation fluid containing adrenaline is thought to be of benefit in this respect. We designed a prospective study assessing the efficacy and safety of using perioperative adrenaline during phacoemulsification, as an adjunct to preoperative topical mydriatics. Forty-two cases were randomized to receive intraocular irrigation fluid with or without 1:1,000,000 adrenaline, as a study or control group. Diameter of the pupil, pulse rate, systolic and diastolic pressure before-phaco, after-phaco-before-I/A and after-I/A were measured. All of the operations were performed by the same surgeon with the same technique. The pupil size after-phaco-before-I/A was 8.00 mm in the study group and 5.96 mm in the control group. The mydriasis maintained during phacoemulsification was significantly greater in the study group, p < 0.00001. The pupil size after-I/A was 8.03 mm in the study group, and 5.54 mm in the control group. The mydriasis maintained during I/A was significantly greater in the study group, p < 0.00001. Pulse rate and blood pressure in patients of the study group, even those with hypertension, showed no significant fluctuation during the surgery. We concluded that intraocular irrigation with 1:1,000,000 adrenaline was a safe and effective way of maintaining mydriasis during cataract surgery.

Blood Pressure↗
PubMed1991

The effect of 0.1% Indomethacin eyedrops on cataract surgery.

Topical use of Indomethacin was documented to prevent surgically induced miosis, and it reduced postoperative inflammatory response. We collected 26 consecutive cataract eyes. Seventeen eyes in the study group received topical 0.1% Indomethacin eyedrops from one day before surgery until two weeks after surgery, in addition to the routine medications. Nine eyes belonging to the control group received the routine medications only. The parameters of our study included the measurement of the pupil diameters in surgery, the central corneal thickness, the intraocular pressure, and the anterior chamber reaction before and after surgery. The results revealed that topical use of 0.1% Indomethacin eyedrops could prevent intraoperative miosis and reduce postoperative corneal edema and anterior chamber reaction, but it did not show much influence on intraocular pressure.

Cataract Extraction↗