ABSTRACT
To evaluate amblyopic scotoma and the most affected neural cells in suppressive phenomena, eight patients with deep amblyopia from strabismus (visual acuity of the amblyopic eye between 4/50 and 2/10) underwent a pattern electroretinogram (PERG), pattern visual evoked potential (VEP), and event-related potential (ERP) from visual stimuli, and computerized perimetry. The results of stimulation of the amblyopic eye, the leading eye and the leading eye penalized by Ryser filters were compared statistically. Computerized perimetry was used to quantify the depth and amplitude of the amblyopic scotoma. All electrophysiological potentials were reduced in amplitude and the implicit times of VEP and ERP were longer when stimulating the amblyopic eye compared to the leading eye. Only in PERG the penalization induced major changes. Our data suggest that the important suppressive phenomena present in the squint amblyopic eye involve not only the occipital cortex, but also the cognitive areas.
Subject(s)
Amblyopia/physiopathology , Evoked Potentials, Visual/physiology , Scotoma/physiopathology , Strabismus/complications , Visual Field Tests/methods , Adolescent , Adult , Amblyopia/etiology , Child , Electroretinography/methods , Female , Humans , Image Processing, Computer-Assisted , Male , Middle Aged , Photic Stimulation , Scotoma/etiology , Strabismus/physiopathology , Visual Acuity , Visual FieldsABSTRACT
The authors report a preliminary study on the usefulness of Ryser filters fixed on a pole to evaluate the degree of penalization needed to induce the imbalance of visual inputs coming through the right and the left eye. The method was tested on 87 patients, suffering from pure DVD (22 cases), esotropia associated with dvd (54 cases) and esotropia associated with dvd and dtd (II cases). The ladder, built of stratified polycarbonate, contains eight filters according to the scale 0-1.0-0.8-0.6-0.4-0.3-0.2-0.1-<0.1, and, despite the high penalizing capacity of the last filters, allows a good observation of the examined eye through the pole.
ABSTRACT
We report our results in nystagmus without null point surgery, utilizing a new technique consisting in the placement of a silicone encircling band around the globe over the four recti muscles, in the retroequatorial position. This method was tried only in nystagmus without null point and with both horizontal and vertical movements. We have not observed any ischemic complication of the anterior segment nor any important variation of intraocular pressure probably because the silicone band was not tightened. Other advantages of this method are its reversibility (cutting the silicone band) and the possibility of combining it with recession-resection of recti muscles at the same or at a later date.
