|Year : 1982 | Volume
| Issue : 6 | Page : 539-543
Ocular motility in amblyopic & the fellow eye
Prem Prakash, AK Grover, PK Khosla, DK Gahlot
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
Dr. Rajendra Prasad of Centre for Ophthal. Sciences, New Delhi-29
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Prakash P, Grover A K, Khosla P K, Gahlot D K. Ocular motility in amblyopic & the fellow eye. Indian J Ophthalmol 1982;30:539-43
Von Noorden and Mackenson were the first to point out abnormalities in the motility of the `fellow' eye of the amblyopic subjects. They reported abnormal pursuit movements in the fellow eye of strabismic amblyopes. Fukai, Tsutsui and Nakamura confirmed the existence of abnormalities of pursuit in the normal fellow eye of amblyopes and reported the presence of asymmetric versional pursuit in 45% of the follow eyes.
| Materials and methods|| |
The study was carried out on 10 normal subjects 10 strabismic amblyopes and 10 anisometropic amblyopes taken from the ocular motility and amblyopia clinic of Dr. Rajendra Prasad Centre for Ophthalmic Sciences. A full orthoptic work-up and elect ro-oculographic motility testing was carried out as reported earlier (Prakash et al see part 1). The grading and analysis of results was carried out as in the above mentioned work.
| Observations|| |
The observations on fixation, saccadic and pursuit movements in fellow eyes of amblyopes are described below.
Abnormalities in fixation were observed in a few patients [Figure - 2] (F). [Table - 1] shows that unsteadiness of fixation is frequent both in strabismic and anisemotropic amblyopes and wherever present is usually mild in nature.
B. Saccadic movements
No significant abnormalities of saccadie eye movements were observed in the fellow eye of either stabismic or anisometropic amblyopes. [Table - 2].
C. Pursuit movements
The abnormalities observed in pursuit movements were qualitatively the same as have earlier been described by the authors for amblyopic eyes [Figure - 1] (P) and [Figure - 2] (P). The abnormalities were present almost as frequently in the strabismic amblyopes as in the anisometropic amblyopes [Table - 3]. The abnormalities in light adapted state appear to be as frequent as in the dark adapted state, although they tended to be less severe in the dark adapted state.
It was observed that average critical frequency (CF) and frequency of disintegration (FD) were lower in the fellow eyes of strabismic amblyopes both in dark and light adapted states as compared to the normal subjects but only the critical frequency in light adapted states was significantly (p<0.05) lower than in normal subjects.
In fellow eyes of anisometropes amblyopes also, mean CF and FD, both in light and dark adopted states, were observed to be lower than in the normal subjects, but these values were not significantly lower as compared to the control subjects on statistical evaluation.
Asymmetry of pursuit
Asymmetry of pursuit, that is difference in nasal and temporalwards movements, was observed in the fellow eye in 2 of the 3 strabismic amblyopes, who showed this abnormality in the amblyopic eye [Figure - 1] (P). It was also observed in the fellow eye of the anisometropic amblyope who showed such asymmetric pursuit in the amblyopic eye [Figure - 2] (P)).
Effect of Dark Adaption
There was no significant difference in the frequency of the abnormalities in the dark and light adapted state in both the strabismic amblyopes, and the anisometropic amblyopes [Table - 1][Table - 3]
Correlation of Abnormalities with Different Parameters
No obvious correlation of fellow eye abnormalities with the vision, fixation, deviation or extent of suppression scotoma in the amblyopic eye was apparent ; either in strabismic or anisometropic amblyopes.
| Discussion|| |
Defects of ocular motility in the fellow eyes of amblyopes have been observed to be similiar in nature to those reported in the amblyopic eyes,,,,, (see part I), although they are much less frequent. It was observed that though fixation and pursuit movements are affected, saccadic movements remain normal in the fellow eyes. This fact is in conformity with the concept that it is primarily the occipital motor system which is affected by abnormal sensory input during the critical period, leading to a decrease in the number of bionocular cells in the occipital cortex.
It is probable that while a milder defect may not affect the fellow eye motility, a severer abnormality of the binocular cells, which serve as afl'rents to the occipital motor cortex, could affect the ocular motility of the `fellow' eye. The defect in frontal motor cortex, being of a much milder nature, as evidenced by the infrequent abnormalities of saccadic movements in amblyopic eyes (Prakash et al, see part 1) does not affect the saccadic motility of the fellow eye.
It has been shown that there is no relation between the extent of ocular motor abnormalities of the fellow eye and the visual acuity, fixation and suppression sacotoma of the amblyopic eye. These observations are in conformity with what has been observed earlier for the amblyopic eyes. Little improvement of fixation and pursuit in dark adapted state was evident. the mean difference in CF and FD not being significantly different in dark and light adapted states. This is again similiar to the observation for amblyopic eyes, suggesting that the functional improvement of amblyopic eye in the dark adapted state does not reflect itself in the ocular motility of these eyes to any great extent.
| References|| |
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[Figure - 1], [Figure - 2]
[Table - 1], [Table - 2], [Table - 3]