Strabismic amblyopia: Part 1: Psychophysics

This is a two‐part survey of current literature concerning strabismic amblyopia. The aim of this review is to bring the optometric practitioner up to date on the status of scientific research into strabismic amblyopia. Part 1 in this series discusses research into strabismic amblyopia from the viewpoint of psychophysical experiments that investigate both spatial and temporal behavioural deficits accompanying strabismic amblyopia. These include deficits in contrast sensitivity, spatial localisation, fixation, ocular motility, accommodation, crowding, attention, motion perception and temporal processing. Part 2 will evaluate neural processing in regard to strabismic amblyopia. It will discuss current understanding of aspects of central processing of visual information and theories regarding neural sites and mechanisms involved in amblyopia.     

Erbium:YAG laser vitrectomy: clinical results

PURPOSE: To evaluate the intraoperative use of a new erbium:yttrium aluminum garnet (YAG) laser vitrectomy system. METHODS: An erbium:YAG laser combined with an infusion-suction system (Wavelight Laser Technology, Erlangen, Germany), equipped with a flexible fiber optic and a hand piece with a 20-gauge end tip and a side opening of 0.6 mm was used. Cutting rates were 2 to 30 Hz, and energies were 20 to 40 mJ. Between January 1998 and January 1999 the erbium:YAG laser system was used in 67 consecutive patients (68 eyes) where vitrectomy was indicated. The patients had a complete eye examination before surgery and postoperatively at 1 to 3 days, 1 week, 3 weeks, and 6 weeks. During surgery, the total time needed for vitrectomy, the laser time itself, amount of energy used, cutting rate, suction, and perfusion, as well as manipulative difficulties and/or complications, were documented. RESULTS: The average laser time was 4.5 minutes for a basic vitrectomy with a setting of 20 mJ, 20 Hz, and suction 100 to 200 mm Hg. Hemorrhages, loose intravitreal, and preretinal membranes of different densities were cut well with adjustment of energy. After a minimal observation time of 6 months (median, 12.7 months) no laser-associated complications were found. CONCLUSIONS: The erbium:YAG laser, combined with an infusion-suction system, offers a new technology for vitreous surgery. Its advantages, compared with mechanical vitrectomy cutters, are higher cutting rates and the modulation of energy. Modifications of the end tip are needed to develop this system further.