Frequency doubling perimetry using a liquid crystal display.

PURPOSE: To compare frequency doubling contrast thresholds using a new liquid crystal window display with those obtained with the commercial video-based Frequency Doubling Technology perimeter. METHODS: One eye of 49 glaucoma patients and one eye of 49 normal controls were tested with the liquid crystal window and Frequency Doubling Technology systems. Both displays employed identical stimulus conditions and test strategies, although the dynamic range of the liquid crystal window-based display was approximately 30% smaller than that of the Frequency Doubling Technology system. Measurements were repeated using the video-based Frequency Doubling Technology perimeter in a subset of 21 eyes. Relationships between and within displays were assessed using a chance-corrected agreement measure (quadratic weighted kappa) and paired measurement differences. Variability was quantified using standard deviation from the mean paired measurement difference. RESULTS: Over the restricted operating range of the liquid crystal display system, between-display and within-video display variability was 2.3 dB and 3.2 dB, respectively, between-display agreement was 0.66, and within-display agreement (test-retest for Frequency Doubling Technology) was 0.65. CONCLUSIONS: Levels of agreement and variability between the two frequency doubling displays were of similar magnitude to repeated (test-retest) Frequency Doubling Technology measures, suggesting that contrast threshold measurements made using the two displays may be used interchangeably. However, the operating range of the current liquid crystal window-based display is smaller.

Megalocornea, developmental retardation and dysmorphic features: two further patients.

Two unrelated children are described with megalocornea, mild-moderate developmental delay, mild joint laxity and a similar dysmorphic appearance, comprising a bossed forehead, hypertelorism, a saddle-shaped nose and a carp-shaped mouth with prominent lips. Similar abnormalities have been observed in previously reported cases of megalocornea/mental retardation and may help to define one subtype of this heterogeneous group of conditions.

Laryngo-onycho-cutaneous syndrome: an inherited epithelial defect.

Three children with an unusual but clearly defined combination of clinical findings that appear to have been inherited in an autosomal recessive manner are described. All had developed laryngeal abnormalities, chronic skin ulceration, nail dystrophy, and conjunctival disease in infancy. In every case, dental enamel was hypoplastic and both skin and mucosal surfaces demonstrated increased susceptibility to trauma. Progression of disease occurred, to life threatening respiratory obstruction in two cases and to effective blindness and fatal respiratory obstruction in the third child. All of these children came from the Pakistani ethnic group. No medical treatment has halted progression of this disease but laser therapy has been partially successful in alleviating laryngeal manifestations. Ultrastructural and immunohistological examination of unaffected skin was undertaken in each child. No abnormality was found in the child with the mildest clinical disease. Both of the other children showed abnormal hemidesmosomes on ultrastructural examination. The most severely affected child also had abnormally weak immunoreactivity with antibodies G71 and GB3 directed against basal cell alpha 6 beta 4 integrin and the basement membrane glycoprotein nicein respectively. These abnormal findings are also seen in skin from patients with junctional epidermolysis bullosa. These three children have the laryngo-onycho-cutaneous syndrome, which may not be rare in their ethnic group. The available clinical and pathological evidence is consistent with this syndrome being caused by an inherited defect affecting the lamina lucida of the skin basement membrane zone. The laryngo-onycho-cutaneous syndrome may therefore represent a new and distinctive type of junctional epidermolysis bullosa.

Posterior lenticonus: clinical patterns and genetics.

Posterior lenticonus is an uncommon abnormality in the shape of the crystalline lens, characterized by a spheroidal or conical protuberance affecting the posterior lens surface. It may be unilateral or bilateral. A male infant with bilateral posterior lenticonus is described, whose mother was found to have bilateral sutural cataracts. The association of cataracts with posterior lenticonus and the genetics of the condition are discussed.