Exfoliation syndrome and exfoliation glaucoma.
Exfoliation syndrome abnormal deposition in the anterior segment of the eye of an unknown substance thought to be related to elastic fibres and basement membrane components is associated with accelerated cataract progression. increased frequency of intraoperative and postoperative complications and increased risk for glaucoma and. therefore, is a clinically important finding. A clear association has been shown with age. The syndrome occurs worldwide but its prevalence seems to vary from country to country. The best-known sign of exfoliation syndrome is deposits of greyish-white material on the anterior lens surface. Sometimes exfoliation material can also be seen at the pupillary border, on the anterior iris surface, corneal endothelium, and on the anterior vitreous face. When clinically detected, exfoliation syndrome is somewhat more often unilateral than bilateral. According to recent investigations clinically unilateral exfoliation syndrome is probably never truly unilateral but rather asymmetric, because exfoliation material has been detected ultrastructurally and immunohistochemically around iris blood vessels of the nonexfoliative fellow eyes. Indeed, electron microscopy identifies in various organs of patients with exfoliation syndrome fibrils similar to those seen in intraocular exfoliation deposits. Other clinical signs associated with exfoliation syndrome are pigment dispersion, transillumination defects of the iris and reduced response to mydriatics. In unilateral exfoliation syndrome, intraocular pressure (IOP) of the exfoliative eye is approximately 2 mmHg higher than IOP of the nonexfoliative fellow eye. Whether elevated IOP, vascular changes or exfoliation syndrome itself is the main factor causing optic nerve head damage and conversion of an exfoliative eye to glaucomatous, is not known. Glaucoma in the exfoliation syndrome has been shown to have a more serious clinical course than in primary open-angle glaucoma (POAG). At the time of diagnosis, IOP and its diurnal variation are generally higher and visual field defects tend to be greater in exfoliation glaucoma than in POAG. Because the decrease in lOP variation and lowering of the mean IOP level has been shown to improve visual field prognosis more in exfoliation glaucoma than in POAG, the glaucomatous process is considered to be more pressure-related in exfoliation glaucoma. Furthermore, progression of optic disc damage has been shown to be similar in exfoliation glaucoma and POAG when lOPs are lowered to a comparable level by the treatment. However, vascular disturbances in the posterior segment of the eye might after all be of equal importance in these two types of glaucoma; optic disc haemorrhages and venous occlusions have been reported to be as frequent in exfoliation glaucoma as in POAG. Perhaps in exfoliation glaucoma circullatory disturbances combined with high IOP lead to a particularly relentlessly progressing form of the disease.
Vesti
E
E
Glaucoma Service, Department of Ophthalmology, Helsinki University Central Hospital, Finland.
Kivelä
T
T
D000818:Animals; D017889:Exfoliation Syndrome / Q000150:complications / Q000453:epidemiology / Q000473:pathology / Q000628:therapy; D005901:Glaucoma / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D006801:Humans