|Year : 1969 | Volume
| Issue : 5 | Page : 222-225
Oguchi's disease- first report from India
Dhanwant Singh, Daljit Singh
Department of Ophthalmology, Medical College, Patiala, India
|Date of Web Publication||11-Jan-2008|
Department of Ophthalmology, Medical College, Patiala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh D, Singh D. Oguchi's disease- first report from India. Indian J Ophthalmol 1969;17:222-5
Oguchi in 1912 described a form of night blindness which was associated with a diffuse greyish white discoloration of the fundus. Over the next few decades more than 60 cases were observed, mainly by Japanese authors. The first European case was described by Scheerer in 1927 and since then 24 cases of this disease have been reported from the continent. Klein in 1939 discussed the first case in the United States and 4 more were reported by Gouras and Carr in 1965.
The features which differentiate most cases of this type of nyctalopia from other disorders of congenital stationary night blindness are the appearance of the fundus and the fact that prolonged dark adaptation will lead to a disappearance of the abnormal fundus discoloration and normalization of all psychophysical testitng parameters (Mizuo's phenomenon). Of note also is the peculiar histological picture. The presence of a large number of cones as well as a second pigment layer led Mann to classify this disorder as an atavistic disorder.
This paper presents three cases of Oguchi's disease that were discovered in a single family living in Patiala. Since this family was being investigated, two more cases have come to our notice, one belonging to Patiala and another coming from a village in Ludhiana.
| Case Report|| |
A 21 year old college girl came with the complaint that she could not adapt in the dark as well as her friends could. She was afraid that the condition might get worse. Her visual acuity was 6/6 J I in both eyes. Fundus examination showed that the optic disc was normal, but the blood vessels appeared unusually dark and the periphery of the retina at places showed grey mottled patches. To have a better look at the periphery of the retina, homatropine was put in both the eyes and the patient made to sit in a semidarkened room with her eyes closed. Pupils did not dilate well even after 1½ hours. This difficulty in getting the pupils dilated was also subsequently noticed in the other two patients. The fundus examination was completely surprisingthe blood vessels no longer looked dark and the peripheral mottling seen earlier had completely disappeared. These changes left us guessing if it could be a case of Oguchi's disease. The patient was reexamined next day after being exposed to daylight for 2 hours. There was no longer any doubt left [Figure - 1],[Figure - 2]. The fundus had a typical greyish white discoloration extending from the periphery right upto the disc. The vessels appeared unusually dark and their branchings and sub-branchings could be visualized with utmost clarity. Many vessels looked wider and fainter and tended to merge with the background (washed out appearance). At some places a vessel segment was seen to be accompanied by a white or a dark line. The periphery of the fundus had a greyish mottled appearance, but there was no actual pigmentary disturbance. With prolonged dark adaptation lasting for about 2½ hours the patient could see as well in the dark as any normal person. Her visual fields with white and coloured objects was normal. Colour vision was also normal.
| Examination of the Family|| |
The patient's father and mother aged 55 and 50 were reported having no visual trouble. They were not even remotely related to each other. Out of two sisters and one brother living in Patiala, one sister aged 19 was reported having the same trouble. Another sister was serving in Rajasthan and nothing was known about her condition: she was called back home for examination. This (27 years old) and the other (19 year old) sister were also found to be suffering from Oguchi's disease. The fundi had typical changes as described in the first case [Figure - 3],[Figure - 4],[Figure - 6]. Perimetric findings, the colour vision and secondary dark adaptation were exactly like those of our first patient.
| Discussion|| |
Oguchi's disease is considered a rare disease and it seems that no case has so far been reported from India. The three cases reported here were discovered only three months back. Since then we have seen two more definite cases of Oguchi's disease, but their families remain to be investigated. Thus it seemed to us that the disease may be much more common than the paucity of reports in the literature would suggest.
The grey white flourescent appearance of the fundus was considered by Oguchi to be due to breakdown of visual purple into visual yellow and visual white and also due to dispersion of pigment from the additional pigment layer that lies between the normal pigment epithelium and the layer of rods and cones. Mizuo's phenomenon is due to the replacement of visual white by visual purple and the return of pigment granules into the cells.
The unusual appearances of the blood vessels need explanation. The vessels look dark due to two reasons firstly they are no more illuminated by the red glow of the fundus and secondly they appear darker by contrast with grey white background. The vastly improved visibility of the finer vessels also depends upon these factors-the fine vessels are no more lost in the general red fundus reflex and secondly they stand out better against whitish background.
The peculiar and characteristic washed out appearance [Figure - 7],[Figure - 8], not mentioned by previous authors can be explained as follows : The vessels are situated on the surface of the retina while their shadow is formed on the deep layers, which in these cases behave like rough mirrors due to collection of visual white in the light adapted state. The bigger the shadow the more the washed out appearance. Such shadows will form only when light falls on the vessel from a side (also see [Figure - 1]). When the light falls along the length of the vessel, there is no such shadow.
An occasional white streak along the vessel is due to chance reflection from a vessel being re-reflected from the mirror like retina into the observer's eye.
| Summary|| |
3 cases of Oguchi's disease in a family belonging to Patiala are described. All the patients suffered from nightblindness, showed typical greyish white fundus discoloration, well marked Mizuo's phenomenon and secondary dark adaptation. A "washed out appearance" of the vessels considered characteristic for this disease is described. The causation of unusually dark vessels, improved visibility of finer vessels, "washed out appearance" of vessels and white streak along some vessels are explained.
| References|| |
Elwyn. H. - Diseases of the retina, p. 305. Blackiston Company, Toronto (1947).
Gouras, P., and Carr. R. (1965): Arch. Ophth., 73; 646.
Klein, B. (1939)-Amer. J. Ophth. 22: 953.
Mann, I., Developmental abnormalities of Eye, ed 2. Philadelphia: J. B. Lippincot Co., 1957 p. 147.
Oguchi, C. (1912)-Griefe Arch. Ophth. 81: 109 cited in 1.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8]