P Vallabhanath | PubMed Health

PubMed2001

Lower eyelid CO(2) laser rejuvenation: a randomized, prospective clinical study.

PURPOSE: The effect of transconjunctival blepharoplasty alone compared with transconjunctival blepharoplasty and CO(2) laser skin resurfacing on lower lid bulging and wrinkles was examined. DESIGN: Randomized clinical trial. PARTICIPANTS: Forty-four subjects, including 13 men and 31 women. METHODS: Subjects were prospectively randomly assigned into two groups: (1) transconjunctival blepharoplasty with immediate CO(2) laser resurfacing or (2) transconjunctival blepharoplasty with CO(2) laser resurfacing 2 months later. Standardized photographs were taken before and 2 months after each procedure. A trained, masked observer graded the photographs. MAIN OUTCOME MEASURES: Bulging and wrinkles of the medial, central, and lateral portions of the lower lid were scored and compared at specified end points. RESULTS: Transconjunctival blepharoplasty alone resulted in an improvement in lower lid bulging in 92% of subjects, whereas lower lid wrinkling worsened in 46%. When transconjunctival blepharoplasty was performed with simultaneous CO(2) laser resurfacing, or with CO(2) laser resurfacing 2 months later, a statistically significant improvement in wrinkles occurred (chi square = 20.625; P < 0.0005). The timing of the procedures had no statistically significant effect on final outcome. No subject had lower lid retraction develop. CONCLUSIONS: Transconjunctival blepharoplasty and adjunctive CO(2) laser resurfacing represents an excellent alternative to transcutaneous lower blepharoplasty. The procedure addresses lower lid wrinkles, skin redundancy, and fat herniation without a scar and with little risk of lower lid retraction.

Blepharoplasty↗

PubMed2000

Ectropion and entropion.

This article reviews the etiology and classification of ectropion and entropion, two of the more common eyelid conditions seen by the ophthalmologist. The preoperative evaluation is important in determining the etiology of the lid malposition. Surgical correction should be directed to the anatomic changes present. A detailed discussion of the more useful surgical procedures to correct ectropion and entropion is presented.

Diagnosis, Differential↗

PubMed1996

Feasibility of a visual prosthesis for the blind based on intracortical microstimulation of the visual cortex.

The feasibility of producing a visual prosthesis for the blind using intracortical microstimulation (ICMS) of the visual cortex was studied in a 42-year-old woman who had been totally blind for 22 years secondary to glaucoma. Thirty-eight microelectrodes were implanted in the right visual cortex, near the occipital pole, for a period of 4 months. Percepts reported as small spots of light, called phosphenes, were produced with 34 of the 38 implanted microelectrodes. Threshold currents for phosphene generation with trains of biphasic pulses were as low as 1.9 microA, and most of the microelectrodes had thresholds below 25 microA. Phosphene brightness could be modified with stimulus amplitude, frequency and pulse duration. Repeated stimulation over a period of minutes produced a gradual decrease in phosphene brightness. Phosphenes did not flicker. The apparent size of phosphenes ranged from a "pin-point' to a "nickel' (20 mm diameter coin) held at arm's length. Phosphene size usually decreased as stimulation current was increased but increased slightly as the train length (TL) was increased. At levels of stimulation near threshold, the phosphenes were often reported to have colours. As the stimulation level was increased, the phosphenes generally became white, greyish or yellowish. Individual phosphenes appeared at different distances from the subject. When two phosphenes were simultaneously generated, the apparent distances of the individual phosphenes sometimes changed to make them appear to be at about the same distance. When three or more phosphenes were simultaneously generated, they became coplanar. Except for rare occasions, phosphenes extinguished rapidly at the termination of the stimulation train. When stimulation TLs were increased beyond 1 s, phosphenes usually disappeared before the end of the train. The duration of phosphene perception could be increased by interrupting a long stimulation train with brief pauses in stimulation. Intracortical microelectrodes spaced 500 microns apart generated separate phosphenes, but microelectrodes spaced 250 microns typically did not. This two-point resolution was about five times closer than has typically been achieved with surface stimulation. With some individual microelectrodes, a second closely spaced phosphene was sometimes produced by increasing the stimulation current. Phosphenes moved with eye movements. When up to six phosphenes were simultaneously elicited, they all moved with the same relative orientation during eye movements. All phosphenes were located in the left hemi-field with the majority above the horizontal meridian. There was a clustering of most of the phosphenes within a relatively small area of visual space. The potentially greater microelectrode density and lower power requirements of ICMS compared with surface stimulation appears encouraging for a visual prosthesis. However, further studies with blind subjects are required to optimize stimulation parameters and test complex image recognition before the feasibility of a visual prosthesis based on ICMS can be established.

Adult↗