Perceptual distortion in homonymous paracentral scotomas.

BACKGROUND: Cortical remapping after peripheral or central visual deafferentation alters visual perception, but it is unclear whether such a phenomenon impinges on areas remote from a scotoma. To investigate this question, we studied variations of perceptual spatial distortion in the visual field of patients with homonymous paracentral scotoma. METHODS: Two patients with right inferior homonymous paracentral scotoma were asked to describe their perception of a series of figures showing two isometric vertical lines symmetrically located on either side of a fixation point. In each figure, the fixation point varied by steps of 2 degrees along a hypothetical vertical line equidistant between the test lines. The lines subtended 20 degrees of visual angle, and the right line passed through the scotoma in both cases. Time for spatial distortion to manifest was recorded. RESULTS: Both subjects reported that the right line was perceived as shorter than the left one. The line shortening varied in magnitude with the distance of the fixation point from the end of the line and was more pronounced when the distance increased. Moreover, perceptual line shortening appeared 5-10 seconds after steady fixation, but values of shortening varied during the following 10 seconds. In addition, the right line appeared uninterrupted or slightly blurred in the scotoma region. CONCLUSIONS: These observations reflect long-range cortical reorganization after brain damage. Larger receptive fields in the periphery of the visual map could explain why perceptual shortening is more pronounced with increased eccentricity.

Primary vitrectomy without scleral buckling for pseudophakic rhegmatogenous retinal detachment.

PURPOSE: To report the anatomic and functional results of primary vitrectomy without scleral buckling for the treatment of pseudophakic rhegmatogenous retinal detachment (PsRD). DESIGN: Prospective, nonrandomized surgical technique study. METHODS: One hundred eyes of 98 patients with PsRD were operated by vitrectomy alone. Internal subretinal fluid drainage, cryocoagulation and/or endolaser and fluid-air exchange with sulfur hexafluoride 20% was applied in all cases. The preoperative and postoperative characteristics were analyzed. Main outcome measures were anatomic success rates after initial surgical intervention and after reoperation for primary failures, visual outcome at the last follow-up visit, and complications. RESULTS: Mean follow-up +/- standard deviation (SD) was 12 +/- 6.3 months (range, seven to 36 months). Mean final visual acuity +/- SD was 0.42 +/- 0.45 logarithm of the minimum angle of resolution (logMAR) compared with 0.95 +/- 0.73 logMAR before surgery (P < .01). Mean number +/- SD of retinal breaks found before surgery was 1.36 +/- 1.12 (range, zero to five), and an additional 1.58 +/- 2.26 (range, zero to 15) retinal breaks were found during surgery. The retina was reattached successfully after a single surgery in 92 eyes (92%). Recurrence of retinal detachment occurred in eight eyes (8%), caused by proliferative vitreoretinopathy in six eyes (75%) and by new breaks in two eyes (25%). Final anatomic reattachment was obtained in these cases after a mean of 1.75 subsequent operations. Three eyes required permanent silicone oil tamponade so that final anatomic success was achieved in 97 eyes (97%). The most common postoperative complication was ocular hypertonia of more than 21 mm Hg, observed in 36 (36%) eyes, which was managed successfully. CONCLUSIONS: Primary vitrectomy without scleral buckling provides a high anatomic success rate in eyes with PsRD and is associated with few complications.