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Show Jounull of C1iniCilI Neuro- ophthalmology ! O( 2): 118- 120, 1990. © 1990 Raven Press, Ltd., New York Inferonasal Quadrant of the Visual Field Is Not Constricted in Patients with Infantile Esotropia When Evaluated by Means of Automated Perimetry Ivan O. Haefliger, M. D., Avinoam B. Safran, M. D., Bernadette Mermillod, B. S., and Andre Roth, M. D. It has been stated that the inferonasal quadrant of the visual field is constricted in patients with dissociated vertical deviation. If this were true, it would be of clinical importance when assessing the visual field of patients with infantile esotropia. In addition, it could corroborate the hypothesis of an abnormal chiasmatic decussation in this condition. To assess this issue, we compared the sensitivity in the two inferior quadrants of the visual field in two groups of subjects by means of automated perimetry. The first group included 18 patients with infantile esotropia and the second, 14 normal subjects. Findings did not show any significant difference between these two groups of subjects and therefore indicate that changes in the inferonasal quadrant of the visual field are unlikely to occur as a result of infantile esotropia. The hypothesis of abnormal chiasmatic decussation in infantile esotropia is reconsidered, based on these results. Key Words: Infantile esotropia- Abnormal chiasmatic decussation- Visual field. From the C1inique d'Ophtalmologie, H6pital Cantonal Universitaire de Geneve ( I. O. H., A. B. S., A. R.), and the Centre d'infonnatique hospitaliere, H6pital Cantonal Universitaire de Geneve ( B. M.), Geneva, Switzerland. Address correspondence and reprint requests to Dr. l. O. Haefliger, C1inique d'Ophtalmologie, H6pital Cantonal Universitaire de Geneve, 24 Rue Micheli- du- Crest, 1211 Geneve 4, Swit" t · r! and 118 It has been stated that patients with dissociated vertical deviation ( DVD) had asymmetric visual evoked potentials ( 1). Similar abnormalities in the visual evoked potentials have also been found in albinoid subjects ( 2), who are known to have an abnormal chiasmatic decussation ( 3). Therefore, it has been suggested that patients with DVD could also have an abnormal chiasmatic decussation ( 1). In addition, it has also been indicated that subjects with DVD demonstrate a reduced sensitivity in the inferior nasal quadrant of the visual field ( 4), which could corroborate the hypothesis of an abnormal chiasmatic decussation in this condition. However, this hypothesis was recently challenged by investigators who failed to find any abnormality in the visual evoked potentials of patients with DVD ( 5). The purpose of our study was to assess whether, in patients with DVD, reduction in sensitivity in the inferonasal quadrant of the visual field could be confirmed. SUBJECTS AND METHODS Two groups of subjects were studied. The first group consisted of 14 normal subjects, aged 12- 20 years ( mean, 15). All of them had a visual acuity of 20/ 20 or more, with a refractive error less than 1.75 diopters. All had normal stereoscopic vision evaluated by means of the Titmus test, and the remaining ophthalmological examination results were within normal limits. The second group consisted of 18 subjects, aged 12- 44 years ( mean, 18), suffering from infantile esotropia. This condition was defined as esotropia with onset during the first 6 months of life, the presence of a latent nystagmus, the presence of a DVD, and a poor stereoscopy VISUAL FIELD IN INFANTILE ESOTROPIA 119 ( 6,7). In this group of subjects, visual acuity was superior to 20/ 25 except in one patient's eye showing marked amblyopia. Refractive error in these patients did not exceed 2.00 diopters. All affected subjects had been operated on a few years prior to this study by means of a classical recessionresection procedure on horizontal muscles. Subjects underwent an automated static perimetry evaluation by means of the Octopus 2000R. Differential light threshold sensitivity was assessed with the " self- user" Sargon program using the normal " up and down" strategy. Differential light threshold was measured along both 2250 and 3150 meridians, within a 250 area from the foveola. Along each of these two meridians, threshold was measured at seven different locations ( Fig. 1). During the same session, for each tested eye, examinations were repeated three times, and the values measured along the inferotemporal meridian were averaged and compared with those measured along the inferonasal meridian, using a Student's t- test. RESULTS We performed 84 examinations on 28 eyes in the group of normal subjects and 105 examinations on 35 eyes in the group of subjects with infantile esotropia. In normal subjects, the mean difference in sensitivity between the inferotemporal and inferonasal meridians (± SD) was + 1.2 dB (± 5.3), with the mean's 95% confidence intervals ranging from - 0.8 dB to + 3.3 dB. In the group of affected patients, the mean difference was + 1.6 dB (± 5.8), with the mean's 95% confidence intervals ranging from - 0.4 dB to + 3.7 dB ( Table 1). When comparing results from both groups, no statistically significant difference was found ( p = 0.77). The difference between the means of each of these groups is 0.4 dB. The 95% confidence interval for this difference ranges from - 2.4 dB to + 3.2 dB. DISCUSSION Our results show a slight but not significant nasotemporal asymmetry in the differential light threshold in both groups of subjects. In addition, no statistical difference was found between the results of normal subjects and patients with infantile esotropia. These findings contrast with the previous observations of Fusco et al. ( 4). It could be due to the fact that, in that study, differential light threshold was measured with a Tiibingen perimeter, which is slightly less sensitive than Octopus perimetry ( 8). Based on our results, we feel that alteration in the inferior nasal quadrant in the visual field should not be expected in patients with infantile esotropia. It should, however, be noted that in our study, visual field was evaluated only by means of light stimuli that were white, small, static, and of short duration. Therefore, we cannot entirely rule out abnormal chiasmatic decussation ofaxons carrying other kinds of visual information ( 9). TABLE 1. Differences in light threshold between temporoinferior and nasoinferior sectors of the visual field of normal and infantile and esotropic subjects 20° .......-------------..., Normal subjects ( n = 28 eyes), dB Subject 00 as Infantile esotropic subjects, ( n = 35 eyes), dB Su~ ect 00 as - 200l- -- J - 20° - 10° 0° 10° 2cf FIG. 1. Schematic representation of the locations in which differential light threshold has been measured in the two inferior quadrants of the visual field. For normal subjects, mean ± SO: + 1.2 ± 5.3 dB; confidence interval ( Ci) ( 95%): - 0.8 dB-+ 3.3 dB. For patients with infantile esotropia, mean ± SO: + 1.6 ± 5.8 dB; Ci ( 95%): - 0.4 dB-+ 3.7 dB. 0° • • ••• • • • • • • • • • 12 34 567 89 10 11 12 13 14 - 4.7 + 6.0 0.0 + 14.7 - 5.0 + 0.7 + 0.7 + 3.0 + 3.0 + 9.3 - 3.3 + 5.0 - 1.0 + 1.0 + 1.8 0.0 - 3.7 - 2.3 - 11.3 + 5.3 + 3.7 + 6.0 - 0.7 + 7.0 - 5.0 + 6.3 - 3.3 + 1.3 1 23 4 56 7 8 9 10 11 12 13 14 15 16 17 18 - 0.7 + 4.5 - 2.3 - 8.0 - 1.0 + 5.0 + 1.7 - 0.7 + 6.7 0.0 - 4.0 + 9.0 0.0 + 6.7 + 6.3 - 4.7 + 8.7 + 3.3 - 15.0 + 4.0 - 10.3 - 2.3 + 7.7 + 2.7 + 3.7 + 10.3 + 4.3 + 1.3 - 3.3 + 10.0 + 3.0 + 6.3 + 1.3 + 7.7 - 4.3 1elin Neuro- ophthalmol, Vol. 10, No. 2, 1990 120 I. O. HAEFLIGER ET AL. Patients with infantile esotropia show abnormal optokinetic nystagmus ( OKN). In these patients, OKN changes are characterized by the fact that, on monocular stimulation, a visual stimulus elicits a much larger nystagmus when moving in the temporonasal direction than when moving in the nasotemporal direction. A similar alteration has also been reported in human albinos ( 1) and in phylogenetically old mammalian species ( 10); since it has been established that in both of them a majority of fibers cross in the chiasma, the question of a relation between OKN and chiasmatic abnormalities has been raised ( 1). However, asymmetry in monocularly induced OKN in patients with infantile esotropia has been assumed to originate from the occipital cortex ( 11). Thus, there is now little functional evidence of abnormal chiasmatic decussation in infantile esotropia. REFERENCES 1. Fitzgerald BA, Billson FA. Dissociated vertical deviation: evidence of abnormal visual pathway projection. Br JOphthaImol 1984; 68: 801-- 6. 2. Creel 0, Wikop CJ, King RA. Asymmetric visual evoked potentials in human albinos; evidence for visual system anomalies. Invest Ophthalmol Vis Sci 1974; 13: 430- 40. 3. Guillery RW, Okoro AN, Witkop CJ. Abnormal visual pathways in the brain of a human albino. Brain Res 1975; 96: 373- 7. 4. Fusco R, D'Aietti M, Verriest G. The visual field in alternating hyperphoria. Bull Soc Beige Ophtalmol 1982; 203: 123-- 8. 5. Kriss A, Timms C, Elston J, Taylor 0, Gresty M. Visual evoked potentials in dissociated vertical deviation: a reappraisal. Br JOphthalmol 1989; 73: 265- 70. 6. Lang J. Der kongenitale oder friihkindliche Strabismus. Ophthalmologica 1967; 154: 201-- 8. 7. Nelson LB, Wagner RS, Simon JW, Harley RD. Congenital esotropia. Surv Ophthalmol 1987; 31: 363-- 83. 8. Mills RP, Hopp RH, Drance SM. Comparison of quantitative testing with the Octopus, Humphrey and Tiibingen perimeters. Am JOphthalmol 1986; 102: 496- 504. 9. Smith SA, Kellis CJK, Smith SE. Inequality of the direct and consensual light reflexes in normal subjects. Br JOphthalmol 1979; 63: 523- 7. 10. Precht W. Anatomical and functional organisation of optokinetic pathways. In: Lennerstrand G, Zee OS, Keller EL, eds. Functional basis of ocular motility disorders. Oxford: Pergamon Press, 1982: 291- 302. 11. Tychsen L, Lisberger SG. Maldevelopment of visual motion processing in humans who had strabismus with onset in infancy. JNeurosci 1986; 6: 2495- 508. |
