By Marcello Cherchi, MD PhD
For patients
In some people, eye movement problems seem to happen with psychiatric problems, though this is usually difficult to figure out.
For clinicians
Overview
There is a modest literature regarding ocular motor abnormalities in psychiatric disease, and most (though not all) of this literature pertains to schizophrenia. This is a difficult area to study because it can be challenging to determine whether a given ocular motor finding is attributable (1) to psychiatric disease, or (2) to the centrally-acting medication used to treat that psychiatric disease, or (3) to an independently occurring vestibular problem. Practically, a clinician needs to keep these different possibilities in mind when interpreting ocular motor findings in patients with psychiatric disease.
Introduction
Ocular motor abnormalities have been reported in patients with various psychiatric diseases who do not complain of vestibular symptoms (Kiyomizu et al. 2009; Lipton et al. 1983). Some studies report similar ocular motor findings in schizophrenics and patients with other psychiatric pathology (Lipton et al. 1980; Yee et al. 1987), and therefore conclude that such findings cannot distinguish among these psychopathologies. Some studies conclude that ocular motor abnormalities cannot even distinguish patients with psychiatric disease from those without (Levy et al. 1983).
Most literature regarding ocular motor findings in psychiatric disease pertains to schizophrenia. Less commonly studied psychiatric diseases include psychosis (Holzman et al. 1980) and “manic-depression” (now renamed bipolar disorder) (Jones and Pivik 1983; Lipton et al. 1980).
Epidemiology
As far as schizophrenia is concerned, some studies observe that up to 80% of patients have detectable ocular motor abnormalities (Latham et al. 1981).
Genetics
A number of studies of smooth pursuit abnormalities in schizophrenics and their (non-schizophrenic) relatives suggest that there is likely a genetic mechanism underlying these ocular motor findings (Holzman et al. 1977; Holzman et al. 1976; Latham et al. 1981; Lipton et al. 1983). For example:
- Holzman and colleagues note that, “Disordered smooth-pursuit eye movements occur in a high percentage of schizophrenic patients and their first-degree relatives. A test of the hypothesis that these disorders represent a genetic indicator of schizophrenia was undertaken by testing pursuit eye movements in a sample of monozygotic and dizygotic twins discordant for clinical schizophrenia. Deviant eye tracking is significantly concordant within monozygotic twin pairs, and less so within dizygotic twin pairs discordant for schizophrenia. A genetic interpretation is consistent with these results” (Holzman et al. 1977).
- As far as schizophrenia is concerned, Latham and colleagues note that, “Between 65% and 80% of schizophrenics and about 45% of their first-degree relatives have disordered horizontal pursuit eye movements and that vertical pursuit is similarly impaired,” and since such ocular motor abnormalities appear “in a significant proportion of unaffected first-degree relatives of schizophrenic patients… it seems to have a strong genetic component” (Latham et al. 1981).
While these conclusions are suggestive, no specific genes have yet been identified to explain the ocular motor findings.
Pathophysiological mechanism of disease
The mechanism by which psychiatric disease may be connected with ocular motor abnormalities is not known. Latham and colleagues (Latham et al. 1981) suggest that cortical dysfunction underlies abnormal optokinetic and pursuit eye movements in schizophrenics.
Testing: Instrumented ocular motor examination
Latham and colleagues (Latham et al. 1981) review literature concluding that, “Between 65% and 80% of schizophrenics… have disordered horizontal pursuit eye movements and that vertical pursuit is similarly impaired.”
Latham and colleagues studied full field optokinetic responses and partial field optokinetic responses by electronystagmography in 12 schizophrenics and 5 normal subjects and reported that, “The large differences in dysrhythmia between the nystagmus types in all 12 subjects are consistent with two separate nystagmus mechanisms. The reflex form of OKN (full-field OKN), which involves a simple, direct brain mechanism, is without exception more regular and stable than partial-field OKN, although there was more dysrhythmia in the responses of the seven schizophrenics than in the five controls” and conclude that this may be “due to a cortical dysfunction” (Latham et al. 1981).
Several electronystagmographic studies of optokinetic responses report consistent differences between schizophrenics and normal control subjects (Latham et al. 1981; Pawlak-Osińska et al. 2000).
Testing: vestibular
There is disagreement in the literature regarding whether schizophrenic patients exhibit consistently different caloric responses from normal controls (Kiyomizu et al. 2011; Levy et al. 1978; Pawlak-Osińska et al. 2000).
Differential diagnosis
A significant difficulty in studying ocular motor function in psychiatric disease is that many of these patients are being treated with one or more centrally-acting medications that can in themselves provoke ocular motor abnormalities. Thus, in a patient being treated for psychiatric disease who has ocular motor abnormalities, it can be difficult to determine whether the findings are attributable to the psychiatric disease itself, or to its treatment, or whether the patient has independently-occurring vestibular pathology.
Treatment
Although a number of studies report ocular motor abnormalities in patients with various psychiatric disease, few or no studies explore whether treatment of the psychiatric disease influences the ocular motor findings.
Prognosis
As far as schizophrenia is concerned, Latham and colleagues report that the ocular motor abnormalities tend to remain stable over time (Latham et al. 1981).
Final comments
The ocular motor abnormalities discussed here are not used to confirm or refute the associated psychiatric diagnoses. Rather, we bring this to readers’ attention so that when one is evaluating a patient with diagnosed psychiatric disease, one will bear in mind that some ocular motor findings may be associated with the psychiatric disease itself, rather than reflect primary vestibular dysfunction.
References
Holzman PS, Kringlen E, Levy DL, Haberman SJ (1980) Deviant eye tracking in twins discordant for psychosis. A replication. Arch Gen Psychiatry 37: 627-31. doi: 10.1001/archpsyc.1980.01780190025002
Holzman PS, Kringlen E, Levy DL, Proctor LR, Haberman SJ, Yasillo NJ (1977) Abnormal-pursuit eye movements in schizophrenia. Evidence for a genetic indicator. Arch Gen Psychiatry 34: 802-5. doi: 10.1001/archpsyc.1977.01770190064005
Holzman PS, Levy DL, Proctor LR (1976) Smooth pursuit eye movements, attention, and schizophrenia. Arch Gen Psychiatry 33: 1415-20. doi: 10.1001/archpsyc.1976.01770120019001
Jones AM, Pivik RT (1983) Abnormal visual–vestibular interactions in psychosis. Biol Psychiatry 18: 45-61.
Kiyomizu K, Matsuda K, Torihara K, Nakayama M, Ishida Y, Yoshida K, Tono T (2011) Neuro-otological findings in psychiatric patients with nystagmus. Eur Arch Otorhinolaryngol 268: 1713-9. doi: 10.1007/s00405-011-1524-z
Kiyomizu K, Matsuda K, Torihara K, Nakayama M, Komaki S, Tono T, Ishida Y, Yoshida K, Kimitsuki T (2009) Nystagmus using video-oculography in psychiatric patients. Eur Arch Otorhinolaryngol 266: 1167-74. doi: 10.1007/s00405-008-0848-9
Latham C, Holzman PS, Manschreck TC, Tole J (1981) Optokinetic nystagmus and pursuit eye movements in schizophrenia. Arch Gen Psychiatry 38: 997-1003. doi: 10.1001/archpsyc.1981.01780340049006
Levy DL, Holzman PS, Proctor LR (1978) Vestibular responses in schizophrenia. Arch Gen Psychiatry 35: 972-81. doi: 10.1001/archpsyc.1978.01770320066005
Levy DL, Holzman PS, Proctor LR (1983) Vestibular dysfunction and psychopathology. Schizophr Bull 9: 383-438. doi: 10.1093/schbul/9.3.383
Lipton RB, Levin S, Holzman PS (1980) Horizontal and vertical pursuit eye movements, the oculocephalic reflex, and the functional psychoses. Psychiatry Res 3: 193-203. doi: 10.1016/0165-1781(80)90036-0
Lipton RB, Levy DL, Holzman PS, Levin S (1983) Eye movement dysfunctions in psychiatric patients: a review. Schizophr Bull 9: 13-32. doi: 10.1093/schbul/9.1.13
Pawlak-Osińska K, Kaźmierczak H, Osiński P, Michorzewski A (2000) Electronystagmographic study in chronic schizophrenia. Int Tinnitus J 6: 172-4.
Yee RD, Baloh RW, Marder SR, Levy DL, Sakala SM, Honrubia V (1987) Eye movements in schizophrenia. Invest Ophthalmol Vis Sci 28: 366-74.
