Purpose: To analyse the anterior lens capsule thickness and ultrastructure changes of intumescent white cataracts in comparison with nuclear cataracts toprove possible structural reasons for surgical difficulties with the intumescent white cataract. Methods: Anterior lens capsules from 35 eyes withintumescent white and 35 eyes with nuclear cataracts were analysed for their thickness by semithin sections technique and for morphological characteristics by transmission electron microscopy. Results: Capsule thickness was not significantly different in intumescent white compared to nuclear cataracts (mean values 17.5 and 18.5 mum, respectively, p = 0.369). The main morphological features of capsules were extrusions of capsule at the basement membrane-epithelial border embedding cellular material which were significantly more frequent in intumescent cataracts. Filaments in the basement membrane as well as rarefication of its structure and lamellae were often concomitant with the extrusions. Conclusions: Anterior capsules of whiteintumescent cataracts do not differ in thickness but have different ultrastructure morphology compared to nuclear cataracts. The extrusions of basement membrane at the basement membrane-epithelial border towards epithelium, the filamentary inclusions within basement membrane and its rarefication could be the structural causes of tensile weakness and hence additional reason to surgical problems.
COBISS.SI-ID: 28364505
Purpose:: To investigate the clinical use of the large-field pattern electroretinogram (PERG) as an adjunct test to the International-standard PERGin an unselected sequential cohort of patients referred for routine electrophysiologic assessment. Methods:: Pattern electroretinograms to both 15degrees x 11 degrees (International Society for Clinical Electrophysiology of Vision Standard) and 30 degrees x 22 degrees (large field) checkerboard field sizes were recorded in 277 consecutive electrophysiology patients, aged 10-79 years. Most patients had additional tests including full-field electroretinogram, electrooculogram, multifocal electroretinograms, or cortical visual evoked potential. Patient data were compared with data from 27control subjects. Results:: Satisfactory 2-field PERG data were obtained in 91% (N = 253) of patients; data from 24 patients (9%) were excluded because ofpoor compliance (n = 17) or nystagmus (n = 7). Standard PERGs were consistent with macular dysfunction in 44% of cases; large-field PERG revealedmacular dysfunction in an additional 8% of eyes and helped to distinguish between localized central, predominantly paracentral, and widespread macular dysfunction. The results were consistent with multifocal electroretinogram and/or imaging studies on the same patients. In some patients with optic nerve disease, the large-field PERG provided clearer evidence of normal macular function than the standard PERG. Conclusion:: Routine use of the large-field PERG is a valuable complement to standard-fieldPERG testing in the evaluation and management of patients with different forms of macular or generalized retinal dysfunction and can be useful in patients with optic nerve disease.
COBISS.SI-ID: 29372121
The aim of this study was to differentiate S-cone responses from other retinalactivities using various recording conditions and to optimize these recording conditions for clinical diagnostics. S-cone responses to blue stimuli (449 nm) were studied in 20 healthy subjects and four patients with enhanced S-cone syndrome. The time-integrated luminance of the stimulus variedfrom 0.008 to 1.0 cd s/m(2). Three isoluminant backgrounds were used (100 ph cd/m(2) = 40 sc cd/m(2)): amber (594 nm), green (513 nm), and red (635nm). With low flash strengths (from 0.008 to 0.032 cd s/m(2)), the S-cone response appeared as a single positive peak, while with higher strengths ()/=0.064 cd s/m(2)), it appeared as a second peak that followed the L-cone and M-cone components. With a further increase in flash strength ()/=0.25 cd s/m(2)), the S-cone response interfered with the i-wave of the L-cone and M-cone systems. The wavelength and luminance of the background influenced the suppression of the rods, as well as the L-cone- and M-cone-system activities. The S-cone response was measurable in the presence of the amber and green backgrounds, but its amplitude was higher if a strong red background was used. Thus, the function of the retinal S-cone system can be measured if possible interference from other retinal sources can be minimized by the appropriate combination of stimulus and background parameters.
COBISS.SI-ID: 29237721