Diabetic Eye Disease

Foveal oedema

Fig 1: The fovea: this is the view of an eye a doctor sees looking,  just like a map. The central area of the retina is the 'macula', shown by the dotted black ring. Light focuses here, so any damage may affect a sight. The very central area, the yellow dot, is the the fovea.

Distortion and micropsia arise when the photoreceptors within the deeper layers of the retina become irregularly spaced. Such symptoms are typical of diabetic maculopathy, but not typical of proliferative retinopathy which is characteristically asymptomatic until an acute vitreous haemorrhage occurs.

Cataract occurs at an earlier age than usual in diabetes, but these symptoms are not typical.

Retinal vein occlusion may also present with foveal oedema but is less likely as a cause, especially in a relatively young woman without extra vascular risk factors.

Oral hypoglycaemic medication does not cause foveal damage. Although transient blurring of vision may occur when the blood sugar is first brought under control, this is more typical of type 1 diabetes, in which normalization is more rapid and more profound after using insulin for the first time.

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The appearances are of background diabetic retinopathy with hard exudates in a circular or circinate pattern at the fovea. Blot haemorrhages are also seen, but there are no new vessels to indicate diabetic proliferative retinopathy. The fact that the fovea is involved in this case will mean that the patient’s vision is affected and the eye can be described as showing ‘maculopathy’.

Diabetic maculopathy as seen here will be treated by focal or ‘grid’ laser coagulation, the primary goal being to seal leaking areas close to the fovea.