SUMMARY Ocular manifestations resulting from Rift Valley fever (RVF) virus infection were studied during an extensive RVF epidemic in Egypt during 1977. Colour photography and fluorescein angiography of 7 serologically diagnosed patients showed the commonest manifestations to be macular, paramacular, and/or extramacular retinal lesions, often occurring bilaterally. Haemorrhage and oedema were frequently associated with the lesions, and vasculitis, retinitis, and vascular occlusion were also observed. Patients were monitored during a 6-month convalescence, and, though resorption of the lesions occurred, approximately half the patients experienced permanent loss of visual acuity. Ocular disease was one form of the clinical spectrum of RVF; acute febrile, encephalitic, and fatal haemorrhagic RVF illnesses were also observed during the epidemic.
The described technique is remarkably accurate and does not require any specially designed implants. It is highly recommended for cases of myopic macular hole retinal detachment with atrophic background and deep posterior staphyloma and for recurrent cases after vitrectomy with or without silicone oil.
The demonstration of serological conversion to Rift Valley fever (RVF) virus in paired acute and convalescent sera established RVF as the cause of two cases of retinitis seen during the 1977 RVF epidemic in Egypt. Colour photography of the retina revealed macular, paramacular and extramacular exudate-like lesions with associated haemorrage and oedema. One patient has not recovered central vision during a six-month convalescence. An ongoing study of a larger group of RVF patients with ocular disease revealed that the findings presented for these two cases represented the types of lesions most frequently encountered during the epidemic.
Advanced chorioretinal atrophy and vascular sclerosis are common findings in high myopia, particularly in association with a posterior staphyloma. Cystic macular degeneration followed by hole formation is therefore more common in eyes with high myopia than in other eyes, and probably most frequent in cases of high myopia with posterior staphylomata, a fact which does not appear to have been pointed out before. Macular holes in posterior staphylomata are very likely to be missed, and it may be impossible to diagnose them for various reasons: (i) Difficult ophthalmoscopy with deep posterior staphylomata.(2) Lack of contrast at the bottom of deep staphylomata with extreme chorioretinal atrophy.(3) The general difficulty of diagnosing all macular holes. This is borne out by the clinical "disappearance" of the hole after drainage of the subretinal fluid in cases of posterior staphylomata with macular hole and central retinal detachment.In my experience all cases of macular holes in posterior staphylomata have been associated with central retinal detachment. The hole may have been present for a long time before the central retinal detachment developed, and the patients all gave a history thal the affected eye had gradually become weak, with more recent deterioration and obscuration of vision.The clinical diagnosis is relatively easy after the detachment as the hole stands out in contrast to the surrounding grey retina, and parallax with the slit lamp and even with the binocular indirect ophthalmoscope becomes valuable in diagnosis. Macular holes do not necessarily lead to retinal detachment, but all the macular holes in cases of central retinal detachment occurred in patients with deep posterior staphylomata. I have not seen a case of macular hole and central retinal detachment in eyes without staphylomata except in association with peripheral retinal breaks and peripheral detachment, in which the diagnosis of a macular hole is very doubtful even after slit-lamp fundoscopy (Rosengren, I966). Rosengren stated that most cases were excessively myopic and that the elevation affected only the posterior parts of the fundus while the periphery remained intact. He did not mention posterior staphyloma though it appears that the condition was present in all his cases.The diagnosis of central retinal detachment due to a macular hole witn a deep posterior staphyloma is very difficult with direct ophthalmoscopy; the thinned central retina stretches across the cavity of the deep posterior staphyloma which is filled with subretinal
The horizontal meridian (foveal horizontal meridian), defined by the entry site and course of the long posterior ciliary arteries, serves as an important surgical landmark if precise external scleral buckling of the fovea is the objective. For practical purposes, foveal horizontal meridian, geometrical horizontal meridian, and optic nerve horizontal meridian need to be distinguished.
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