Elsevier

Ophthalmology

Volume 107, Issue 5, May 2000, Pages 1009-1014
Ophthalmology

Original Articles
Ophthalmoscopic detectability of the parafoveal annular reflex in the evaluation of the optic nerve1: An experimental study in rhesus monkeys☆,

https://doi.org/10.1016/S0161-6420(00)00074-9Get rights and content

Abstract

Objective

To evaluate whether assessment of the ophthalmoscopic visibility of the parafoveal annular reflex is helpful in the detection of optic nerve fiber and optic nerve damage.

Design

Experimental animal study.

Animals

The study was performed in rhesus monkeys, divided into four study groups, with no significant difference in ages of the animals in the various groups. Three of these groups had (1) experimental chronic high-pressure glaucoma (n = 37 monkeys), (2) experimental temporary occlusion of the central retinal artery (n = 19 monkeys), and (3) systemic atherosclerosis and arterial hypertension (n = 13 monkeys). The fourth group was the normal control group (n = 10 monkeys).

Methods

In 60-degree color fundus photographs, taken at baseline and at the end of the study, the ophthalmoscopic detectability of the parafoveal annular reflex was graded, the visibility of the retinal nerve fiber layer was assessed, and neuroretinal rim and parapapillary atrophy were measured.

Main outcome measures

Ophthalmoscopic detectability of the parafoveal annular reflex; visibility of the retinal nerve fiber layer; neuroretinal rim area; size of parapapillary atrophy.

Results

The parafoveal annular reflex was significantly (P < 0.0001) better detectable at baseline of the study than at the end of the study. In all study groups, detectability of the parafoveal annular reflex decreased significantly (P < 0.0001) with decreasing visibility of the retinal nerve fiber layer. In the glaucoma group, parafoveal annular reflex detectability additionally decreased significantly (P < 0.001) with increasing area of beta zone of parapapillary atrophy and with decreasing neuroretinal rim area. In the normal group, the parafoveal annular reflex detectability decreased with increasing age, parallel to a loss in the visibility of the retinal nerve fiber layer. In 23 of 25 (92%) eyes with a complete loss of the visibility of the retinal nerve fiber layer at the end of the study, the parafoveal annular reflex was no longer detectable.

Conclusions

The findings suggest that evaluation of the detectability of the parafoveal annular reflex in routine ophthalmoscopy is a useful additional tool in the qualitative assessment of the retinal nerve fiber layer and optic nerve.

Section snippets

Material and methods

Sixty-degree color fundus photographs taken of rhesus monkey (Macaque mulatta) eyes at baseline and the end of the study were evaluated. The entire study group was divided into the following four groups.

The first group consisted of 37 eyes of 37 monkeys in which experimental glaucoma was unilaterally produced by multiple applications of argon laser to the trabecular meshwork.4 Mean age of monkeys in this group was 19.76 ± 3.07 years (range, 13–24 years), with no significant (P = 0.58)

Results

At baseline of the study, the parafoveal annular reflex was detectable on the photographs of all except 10 (10 of 79 or 12.7%) eyes. The mean score of its ophthalmoscopic detectability was 2.4 ± 1.1 (median: 3; range, 0–3). Taking all eyes at baseline of the study before induction of experimental glaucoma or experimental temporary occlusion of the central retinal artery, the detectability of the parafoveal annular reflex decreased significantly with increasing age (Fig 3), parallel to a

Discussion

The results of this study suggest that qualitative assessment of the retinal nerve fiber layer and an alteration in the appearance of the parafoveal annular reflex on routine ophthalmoscopy are additional tools in the panoply of signs of evaluation of retinal nerve fiber loss and optic nerve atrophy.

In 1925, Alfred Vogt9 noted an alteration in the light reflex pattern in the macula of patients with optic nerve damage. When studying the ophthalmoscopic visibility of the retinal nerve fiber

References (15)

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☆

Supported by grant EY-1576 from the U.S. National Institutes of Health, in part by unrestricted grants from Research to Prevent Blindness, Inc., New York, New York, and by Deutsche Forschungsgemeinschaft (SFB 539).

1

Dr. S. S. Hayreh is a Research to Prevent Blindness Senior Scientific Investigator.

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Copyright © 2000 American Academy of Ophthalmology, Inc. Published by Elsevier Inc. All rights reserved.