Extrafoveal fixation involving the blind spot.

Esotropia that is of such a degree that the image is projected on the physiologic blind spot of the deviating eye is a clinical entity termed the blind-spot syndrome, or when ac­ companied by abnormal sensory findings, the blind-spot mechanism. 1 ' 2 Swan 3-4 divided patients with the blind spot mechanism into four groups, including a group with a combi­ nation of amblyopia and eccentric fixation. However, in no previously reported case has the area of the disk been cited as an extrafo-veal site of monocular fixation. CASE REPORT This 50-year-old white man was first evaluated in December, 1968. H e gave a history of being hit in the right eye with a stone in boyhood, but there was no known sequelae. He also stated that he had surgery at the age of 22 years for "crossed eyes," but medical records of this hospitalization were not available. He noted that this operation produced no noticeable change in his deviation postoperatively. The patient denied diplopia or confusion of images and was no longer concerned about cosmetic im­ provement. Examination revealed his best corrected visual acuity was R E : 20/20 and L E : finger counting at three feet. Cycloplegic retinoscopy findings were R E :-2. 0 0 sph. C + 1 0 0 cyl. ax. 78° and L E : — 1.S0 sph. C + 5 0 cyl. ax. 90°. The pupils were of equal size and responded normally to light and ac­ commodation. External eye examination was normal with the exception of the left esotropia of approximately 18 degrees by Hirschberg testing. On cross cover test­ ing, reliable prismatic measurements of the deviation were unobtainable because of the eccentric fixation. No fixation movement of either eye occurred when the fellow eye was covered. Ductions and versions were indicative of a comitant left esotropia. The Worth Four-Dot test response indicated deep sup­ pression of the left eye, and the Titmus Stereotest revealed no stereopsis. Slit-lamp examination of the right eye revealed a diffuse wedge-shaped corneal opacity at eight o'clock with an underlying small iris cleft. Slit-lamp examination of the left eye was normal. Ocu-Gonioscopy of the right eye revealed a 360-degree angle recession and peripheral anterior synechiae ex­ tending from eight to 10 o'clock. Gonioscopy of the left eye was within normal limits. Fundus examination was normal. The visual field revealed a central scotoma, but no physiologic blind spot, …