[Amblyopia. Epidemiology, causes and risk factors]. / Amblyopie. Epidemiologie, Ursachen, Risikofaktoren.

BACKGROUND: Amblyopia is the main cause for mostly monocular, impaired vision in childhood. Treatment and prevention of amblyopia is only effective during childhood. Ophthalmological screening of children does not yet exist in Germany. EPIDEMIOLOGY: The prevalence of amblyopia in Germany is 5.6%, which is higher than in reports from studies in Australia; however, the prevalence of amblyopia is not comparable in these studies due to different definitions of amblyopia and the inclusion/exclusion criteria of the study cohorts. At present it is unknown at what age ophthalmological screening should be carried out to prevent amblyopia and the appropriate frequency of screening examinations. CAUSES: Amblyopia is a disorder of the visual cortex that is due to suppression and deprivation of one eye leading to unilateral visual impairment. Approximately 50% of cases of amblyopia are caused by anisometropia, 25% by strabismus and in every sixth person by a combination of both. Other causes, such as unilateral congenital cataracts are relatively rare. RISK FACTORS: A variety of factors, such as ocular pathologies, premature birth, familial disposition and general diseases are associated with an increased risk for amblyopia.

[Charles Bonnet's syndrome: clinical insights in a fascinating disease]. / Charles-Bonnet-Syndrom--klinische Besonderheiten eines faszinierenden Krankheitsbilds.

Even mentally and cognitively healthy people can experience visual hallucinations. These are called Charles Bonnet's syndrome, named after the Swiss scientist, who first described such perceptions in the 18th century. Usually patients possess insight in the unreality of their visual experiences. The definitions of CBS are not consistent. Visual impairment or blindness is not part of every definition, but often is associated with CBS. Ophthalmologists should be aware of this syndrome, since its prevalence is high among blind or visually impaired people: patients often are reluctant to admit their hallucinatory experiences, because of the fear of being stigmatised. Possibly women are affected more often than men. CBS is well investigated in the elderly, but also young people might experience visual hallucinations. Hallucinatory contents commonly are persons, with varying duration of the hallucinations. Most patients experience more than one hallucinatory episode. CBS is best investigated in patients suffering from AMD. Neuroimaging studies suggest that cerebral abnormalities, mainly in the occipital cortex, might also play a role in the pathogenesis of CBS. Many patients do not require (drug) treatment, since education itself is helpful in most cases. The pathophysiology remains unclear, but there are a couple of theories.

Measuring corneal clouding in patients suffering from mucopolysaccharidosis with the Pentacam densitometry programme.

AIM: To identify a means to objectively measure corneal clouding in patients with mucopolysaccharidosis in a prospective controlled clinical trial. METHODS: Corneal haze was assessed by slit lamp examination and measured using the densitometry programme of the Pentacam, a rotating Scheimpflug camera in 33 mucopolysaccharidoses (MPS) patients and 32 controls. RESULTS: Pentacam measurements were available in 31 right and 31 left eyes of 32 patients and in 32 left and right eyes of 32 subjects in the control group. Slit lamp findings correlated very well with corneal density measurements (Spearman correlation right eye (OD)/left eye (OS)=0.782/0.791). MPS patients had higher density units (median OD/OS=14.1/14.7) than control subjects (median OD/OS=6.7/6.9, p<0.001). In patients, the corneal centre density values (median OD/OS=13.8/14.0) did not differ from corneal periphery values (median OD/OS=14.3/14.7). CONCLUSIONS: The densitometry programme of the Pentacam provides objective measurement of corneal haze in mucopolysaccharidosis patients.

Trochlear palsies caused by isolated trochlear schwannomas.

PURPOSE: To describe clinical features and management of 4 patients suffering from unilateral superior oblique palsies due to MRI-documented trochlear nerve schwannomas. METHODS: Chart reviews of 4 patients seen at the departments of ophthalmogy and neurology at the University of Mainz. RESULTS: All four patients were male, aged 36 to 72 years at initial presentation. None suffered from neurofibromatosis. The history of double vision prior presentation was 9 months to 13 years, follow-up time was 9 to 156 months. Two patients didn't receive any intervention: one remained stable over the follow-up time of 9 months. In patient #2, fourth nerve palsy was diagnosed 13 years prior to confirmation of a trochlear schwannoma by high-resolution MRI. In the third patient disturbing diplopia and head tilt were sufficiently corrected by strabismus surgery (combined oblique muscle surgery). The fourth patient had received stereotactic radiotherapy of an 8 mm schwannoma. He remained unchanged in the orthoptic measurements for 3,5 years. None of these patients developed any additional symptoms or signs of further cranial nerve or central nervous system involvement. CONCLUSION: A trochlear nerve schwannoma is a possible cause of an isolated unilateral superior oblique palsy. MRI is a helpful tool for diagnosis and follow-up. Conservative management seems to be justified as patients can remain unchanged over years.