|Year : 1977 | Volume
| Issue : 1 | Page : 1-4
Daljit Singh, Dhanwant Singh, Dewan Chand Bansal
Department of Ophthalmology Medical College, Amritsar, India
Department of Opbthalmology Medical College, Patiala
|How to cite this article:|
Singh D, Singh D, Bansal DC. Oguchi's disease. Indian J Ophthalmol 1977;25:1-4
This is peculiar and distinctive bilateral condition, congenital and stationary in type and heriditary in nature. It is characterized by structural anomalies in the retina and a retardation of dark adaptation amounting to night blindness.
The condition was first described by Oguchi  in 1907. Over the next few decades 60 cases were observed, all by Japanese authors. The first European case was described in 1927 and the first American case was described in 1939 , . Till now about 110 cases have been reported in the world literature.
The first Indian report of three cases of Oguchi's disease was made by us  in 1969. Soon after this report was presented, two more A cases came to light, which created a suspicion that this condition might be more frequent than the paucity of reports in the literature might suggest. Our suspicion has been amply confirmed by the detection of 16 more cases of Oguchi's diseases.
| Characteristics of Oguchi's disease|| |
The fundus oculi presents a most peculiar appearance. The posterior pole and in many cases the whole of fundus, instead of having a normal orange-red colour, presents a curious shining greyish-pink background, on which the retinal vessels stand out sharply. The vessels appear dark with little distinction between the arteries and the veins. The finer divisions of the blood vessels can be easily followed to their finest ramifications. At places a dark shadow or a bright white line may be seen alongside the blood vessel.
In addition to the above mentioned appearances, three further points have been noted by us:
1. The choroidal vessels are seen less distinctly. 2. The peripheral blood vessels have a very rough appearance and show pigmentlike blotches on or near them. But there is no actual pigmentary disturbance. 3. Many vessels in the periphery look wider and fainter and tend to be lost in the shining greyish-pink background. This appearance has been termed by us as "Washed out appearance".
The most interesting feature of this disease in well marked cases is the reversal of all the features described above, if the patient sits in the dark for about one hour. This is called Mizuo's phenomenon. The retina looks normal and the night-blindness disappears. After the fundus has resumed the normal colour, exposure to room light of 40-50 foot candles soon leads to the appearance of fundus discolouration. It begins with a spotty distribution after about 15 minutes' exposure and within one hour the colour transformation is complete.
In some cases the discolouration of the fundus is mild and Mizuo's phenomenon is slight or absent, but night-blindness is definitely complained of.
[Figure - 1] shows the posterior part of the fundus in a well marked case of Oguchi's disease.
[Figure - 2] shows the periphery of the fundus of the same patient in the light adapted state. Note the pigment like blotches.
[Figure - 3] shows the same periphery of the retina after dark adaptation for one hour. Mizuo's phenomenon has occured.
| Subjective Symptoms|| |
The only symptom is that of night blindness The children do not complain of night blindness, but always show reluctance to move out of doors after sunset. One of our patients (Doctor R.) had always been afraid of the dark. The night blindness disappears after staying in the dark for about one hour. The visual acuity is unaffected in daylight. Visual fields for white and red are normal, but are contracted for the blue.
Francois found that ERG was characterized by the complete absence of scotopic (nightvision) response (b wave) while the photopic (day vision) response (a wave) was present. These functional defects point to a lack of activity of the rods.
| Microscopical Examination|| |
Microscopical examination has been done by Oguchi  and Ida Mann  . Two peculiar features have been noticed
1. The cones are unusually numerous and are present to the practical exclusion of the rods in a large area. Many of the cones are abnormally long and their nuclei are ectopic, i.e. they are outside the outer limiting membrane. The bipolar layer is thicker than normal and the ganglion cell layer is eight to ten cell deep.
2. There is an anamolous layer of tissue between the cones and the pigment epithelium. It is not a true cellular layer, but rather appears as a degenerated syncytial structure containing many pigment granules.
| Classification|| |
Oguchi's disease has been further classified into various types
Type I : Typical cases with marked fund us discolouration, Mizuo's phenomenon and recovery of dark adaptation.
(a) slight fundus discolouration, partial Mizuo's phenomenon and without recovery of dark adaptation.
(b) slight fundus discolouration without Mizuo's phenomenon and without recovery of dark adaptation.
| Heredity|| |
It is universally agreed that the condition is transmitted as an autosomal recessive without sex discrimination. Consanguinity also plays an important part.
| Material Observation|| |
A total of 19 cases have been seen by us till date. They include the three cases reported by us earlier  . The details are as follows:
A. Familial cases - Type of Oguchi's disease
Family No. 1 (all sisters)
1. Dr. S, 27 Female - Type l
2. Dr. S, 21 Female - Type I
3. Miss M, 19 Female - Type I
Family no. 2 (mother and her 4 children)
4. Mrs. S.K. 37 Female - Type II a
5. Miss R.K. 17 Female - Type II a
6. Miss R. 13 Female - Type II a
7. Miss G. 10 Female - Type II a
8. Kaka, 4 Male - Type II a
Family no. 3 (mother and son)
9. Mrs. M.S., 30 Female - Type I
10. Mr. AX., 9 Male - Type I
B. Isolated cases Type of Oguchi's disease
11. Mr. H.R.42 Male, a pharmacist - Type II a
12. Miss G. 14 Female - Type I
13. Mr. S, 61 Male - Type I
14. Dr. R, 24 Male - Type I
15. Miss J. 16 Female - Type I
16. Mr. K. 12 Male - Type I
17. Mr. A.M. 13 Male - Type II a
18. Mr. B.S. 6 Male - Type II a
19. Mr. B.B. 16 Male - Type I
Family no. 1 has already been reported (1969) by us.  All the three families show autosomal recessive inheritence, family no. 2 showing marked penetrance. No history of consanguinity was available.
Patient no. 16 (Mr. K.) was examined by one of us (Dalijit Singh) eight years earlier and was wrongly diagnosed as chorioretinal degeneration.
Patient nos. 2 and 14 were earlier diagnosed by as ophthalmologist as those of a typical retinitis pigmentosa.
Ten patients belonged to Patiala, two came from Nabha, three from Rajpura, two from Delhi, one from Bhatinda and one came from Jammu. Ten patients were females and nine were males. Eleven cases belonged to Type I and 8 cases belonged to Type II a.
| Discussion|| |
The shining greyish pink appearance of the fundus was considered by Oguchi to be due to breakdown of visual purple to visual yellow and visual white, and due dispersal 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 said to be due the replacement of visual white by visual purple and due to the return of pigment granules into the cells. There is no proof for this theory.
The unusual appearances of the blood vessels have been explained by us as follows
The blood vessels look dark due to two reasons-firstly they are no more well illuminated by the red glow of the fundus, and secondly, they appear darker by contrast with greyish background. The improved visibility of the finer vessels also depends upon these very factors-the fine vessels are no more lost in the general red fundus ground and secondly they stand out better on a changed background.
The peculiar and characteristic "washed out appearance" not noted by previous authors has been explained by us as follows
The vessels are situated on the surface of the retina, while their shadows are formed in the deeper layers, which in the light adapted state behave like rough mirrors and thus spread and break the shadows. Such shadows form only when the light falls on the vessels from the side. When the light falls along the length of the vessel, no such shadows are formed.
An occasional white streak seen along the vessels is probably due to chance reflection from a vessel, being rereflected from the mirrorlike retina into the observer's eye.
The object of this paper is to demonstrate typical appearances of Oguchi's disease. The disease appears to be much more common than the paucity of reports in the literature would suggest. If the typical appearances are kept in mind, many more patients suffering from this disease will be detected on routine examination in ophthalmic clinics.
All the patients of Oguchi's disease suffer from defective adaptation to darkness. Their employment in army, navy, airforce, railways and roadways and in many other fields is frought with great danger. Since most patients are used to their slow adaptation since birth, they may never complain and thus remain undetected. On top of it most patients would not volunteer any information, if it would mean loss of a job. Diagnosis of Oguchi's disease by the ophthalmologist without the assistance of the patient, has therefore great importance.
| Summary|| |
The fund us appearances in cases of Oguchi's disease are described with illustrations. The literature is briefly surveyed. Nineteen cases seen by the authors are described. They include 10 familial and 9 isolated cases show autosomal recessive inheritence, one family showing marked penetrance. It is felt that Oguchi's disease is much more common than the paucity of reports in the literature would suggest.
| References|| |
|1.||Elwyn, H., 1947, Diseases of the retina, 305. Blakiston Company, Toronto. |
|2.||Francois and Verriest, 1954, quoted by Duke Elder (1964) Sys. of Ophthal. part 2, 642. |
|3.||Gouras. P. and Carr, R., 1965. Arch. Ophthal., 73,646. |
|4.||Klein, B., 1939, Amer. J. Ophthal. 22, 953. |
|5.||Mann, 1., 1957, Developmental abnormalities of the eye, Ed. 2, Philadelphia: J.B. Lippincot Co., 147. |
|6.||Oguchi, C. 1912, Griefe Arch. Ophthal 81, 109. |
|7.||Oguchi, C., 1925, quoted by Duke Elder, Sys. of Ophthal. Vol. III, part 2, 640, Henry Kimpton, London (1964) |
|8.||Singh D. and Singh D., 1969, J. of All India Ophthal. Soc. 17, 222. |
[Figure - 1], [Figure - 2], [Figure - 3]