Roy W. Beck

Anterior Ischemic Optic Neuropathy: IX. Cup-to-disc Ratio and Its Role in Pathogenesis

The optic disc appearance in the normal fellow eye of 126 patients with nonarteritic anterior ischemic optic neuropathy (n-AION) was compared with the discs in 23 patients with arteritic AION (a-AION) and 122 normal subjects. The number of discs with no cup was significantly greater (P less than 0.001) and the number of discs with a large cup was significantly fewer (P less than 0.001) in the n-AION group compared to the other two groups. No significant differences were found in cup size between the a-AION and normal groups. The pathogenesis of n-AION appears to be multifactorial. There is overwhelming evidence that ischemia is the primary factor. The size of the optic disc also plays a role, probably through a compressive effect at the level of the lamina cribrosa on axons subjected to ischemia. In contrast, a-AION occurs from posterior ciliary artery occlusion and disc size is not a factor.

Optic Disc Structure in Anterior Ischemic Optic Neuropathy

The etiology of anterior ischemic optic neuropathy (AION), when not associated with giant cell arteritis, is usually unknown. Clinical, pathologic, and experimental studies have not determined a cause. The optic disc appearance in both the involved and normal fellow eye was studied in 51 patients with acute nonarteritic AION. The number of discs (both involved and fellow) without a physiologic cup was significantly greater than would be expected from normal population studies. The etiology of nonarteritic AION may be related to the anatomic configuration of the optic nerve.

Is There a Racial Difference in Physiologic Cup Size

Although many clinicians believe that there is a racial difference in the size of the physiologic cup, this premise has not been studied. To evaluate this, we prospectively examined 100 black and 100 white volunteers. Stereoscopic optic disc photographs taken of each subject were masked to block out the fundus pigmentation, randomized, and then evaluated by an experienced clinician. The average cup/disc ratio in blacks (0.35) was significantly greater (P less than 0.0001) than that in whites (0.24) for both right and left eyes. Forty percent of the optic discs of blacks and 14% of the optic discs of whites had a cup/disc ratio greater than or equal to 0.4.

Specular Microscopy Ancillary Study Methods for Donor Endothelial Cell Density Determination of Cornea Donor Study Images

Purpose: To describe reliable methods for determining central corneal endothelial cell density (ECD) in a multicenter eye bank study. Methods: The Specular Microscopy Reading Center utilized a dual-grading procedure and adjudication process to classify image quality and determine ECD for a subset of donor endothelial images obtained in the Specular Microscopy Ancillary Study, which is part of the Cornea Donor Study.1 Two certified readers classified images as analyzable (excellent, good, fair) or unanalyzable and determined the ECD using a variable frame technique. An adjudicator also evaluated the images if quality classifications by the two readers differed by one grade, if any reader found the image unanalyzable, and/or if the ECD determination between the two readers was ≥ 5%. Results: Image quality categorization by the two readers was identical for 441 (64%) of 688 donor images. The ECD differed by < 5% for 442 (69%) of the 645 analyzable images. The ECD determined by the adjudicator was < 5% different than the ECD determined by at least one reader for 193 (95%) of the 203 remaining images. Conclusions: The dual-grading and adjudication procedures produce reliable, reproducible assessments of image quality and ECD. The importance of two independent readings is evident in that image quality ratings differed between the two readers by one grade in 36% of all images and ECD counts differed by ≥5% for 31% of analyzable images.

Orbital Emphysema As An Ophthalmologic Emergency

Orbital emphysema is generally a benign, self-limited condition. However, if a fracture produces a ball-valve effect allowing air to enter but not to leave the orbit, and if the orbital septum remains intact, then extremely high intraorbital pressure and visual loss is possible. Two cases are described of visual loss from orbital emphysema, in a 33-year-old man and a 28-year-old man, which were successfully treated by a lateral canthotomy and cantholysis.

Familial recurrent Bell's palsy with ocular motor palsies

We studied a family in which the father and 7 of 10 children had episodes of Bells palsy. Five of the eight affected family members also had ocular motor palsies. Facial nerve and blink reflex studies in four affected siblings demonstrated asymmetrically reduced amplitude of evoked responses without delaved conduction. EMG revealed siens of chronic denervation and reinnervation in ail four patients; two had synkineiis. Three siblings had diabetes mellitus, but with no clinically evident polyneuropathy.

Endothelial Morphometric Measures to Predict Endothelial Graft Failure After Penetrating Keratoplasty

IMPORTANCE Endothelial morphometric measures have potential value in predicting graft failure after penetrating keratoplasty. OBJECTIVE To determine whether preoperative and/or postoperative central morphometric measures (endothelial cell density [ECD], coefficient of variation [CV], and percentage of hexagonality [HEX]) and their postoperative changes are predictive of graft failure caused by endothelial decompensation after penetrating keratoplasty to treat a moderate-risk condition, principally Fuchs dystrophy or pseudophakic corneal edema. DESIGN In a subset of Cornea Donor Study participants with graft failure, a central reading center determined preoperative and postoperative ECD, CV, and HEX from available central endothelial specular images. SETTING Cornea Image Analysis Reading Center of the Specular Microscopy Ancillary Study. PARTICIPANTS Eighteen patients with graft failure due to endothelial decompensation and 54 individuals matched for most donor and recipient measures at baseline whose grafts did not fail. MAIN OUTCOME MEASURE Change in ECD, CV, and HEX values. RESULTS Preoperative ECD was not associated with graft failure (P = .43); however, a lower ECD at 6 months was predictive of subsequent failure (P = .004). Coefficient of variation at 6 months was not associated with graft failure in univariate (P = .91) or multivariate (P = .79) analyses. We found a suggestive trend of higher graft failure with lower HEX values at 6 months (P = .02) but not at the established statistical significance (P < .01). The most recent CV or HEX values, as time-dependent variables, were not associated with graft failure (P = .26 and P = .81, respectively). Endothelial cell density values decreased during follow-up, whereas CV and HEX appear to fluctuate without an apparent trend. CONCLUSIONS AND RELEVANCE Endothelial cell density at 6 months after penetrating keratoplasty is predictive of graft failure, whereas CV and HEX appear to fluctuate postoperatively, possibly indicating an unstable endothelial population in clear and failing grafts. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00006411.

Optic Disc Edema in the Presumed Ocular Histoplasmosis Syndrome

Two patients with presumed ocular histoplasmosis syndrome developed optic disc edema. In both cases the edema resolved without residual impairment of visual function. Although peripapillary changes in ocular histoplasmosis are common, optic disc edema is rare. The pathogenesis of the edema is unknown.