Choroidal neovascular membranes after photodynamic therapy: ultrastructural analysis of two surgically excised membranes.

PURPOSE: To report on the ultrastructural electron microscopic findings of two surgically excised subfoveal choroidal neovascular membranes (CNV) that had undergone photodynamic therapy (PDT). METHODS: Two patients underwent PDT because of subfoveal neovascular membranes (CNV). Due to enlargement of the CNV seen on fluorescein angiography three months after PDT, one patient underwent surgical excision of the membrane; the other patient underwent both surgical membrane excision combined with macular translocation one month after PDT. The membranes were examined under the transmission electron microscope (TEM). RESULTS: The membranes were composed of a core and a rim, the latter being mainly composed of fibrin and collagen fibrils. The core was preeminently composed of endothelium-lined vascular channels associated with retinal epithelium cells. The endothelial cells of blood vessels appeared well-preserved. CONCLUSIONS: The lack of histological signs of recanalization and vascular thrombosis may indicate that in our cases the enlargement of the CNVs seen on fluorescein angiography three months and one month respectively after PDT may originate mainly from reproliferation of choroidal vessels rather than recanalization of previously occluded vessels.

Reliability of standardized echography before vitreoretinal surgery for proliferative diabetic retinopathy.

Standardized A- and B-scan echography was performed in 45 patients (68 eyes) affected by proliferative diabetic retinopathy, before vitreoretinal surgery, to evaluate the percentage of agreement between the ultrasonographic data and the surgical findings. The agreement was quite good for tractional retinal detachment (93%) and for posterior vitreous detachment (91%). The main cause of failure was the presence of vitreoschisis, while preretinal and vitreal membranes can easily be detected.

Echographic study of the vitreoretinal interface in giant retinal tears.

Vitreous and vitreoretinal interface changes were evaluated in giant retinal tears in order to plan surgical approach. Vitreal sineresis was evident in patients affected by primary giant retinal tears; in patients affected by retinal disinsertion the vitreous was adherent to the edge of the posterior flap, and in giant retinal tears secondary to IOL implantation, posterior vitreous detachment but no sineresis was displayed.

Standardized echography, pattern electroretinography and visual-evoked potential and automated perimetry in the early diagnosis of Graves' neuropathy.

Twenty-four patients (47 eyes) affected by Graves' disease were enrolled to evaluate the role of standardized echography, pattern electroretinogram (P-ERG), visual evoked potentials (P-VEPs) and automated perimetry in the early diagnosis of the compressive optic neuropathy (CON). The P-ERG amplitude reduction was the most sensitive parameter to demonstrate an early impairment of the optic nerve (ON) function. We found a significant negative correlation between the ON diameter and the P-ERG amplitude. VEPs responses were also altered, but their ability in detecting an early ON damage was less sensitive and specific than P-ERG. The visual field damage was often aspecific and delayed with respect to electrophysiological alterations.

Responses to chromatic and luminance contrast in glaucoma: a psychophysical and electrophysiological study.

Increasing anatomical evidence indicates that large retinal ganglion cells (M-cells) are preferentially damaged in primary open angle glaucoma (OAG), while the smaller ganglion cells (P-cells) are relatively spared. In 13 patients with defined OAG and modest visual field defects, we evaluated the responses to stimuli that are expected to involve primarily the function of the P-pathway and compared them with those of control subjects. The psychophysical contrast sensitivity (CS), the PERG and the VEPs were measured for red-green gratings of pure chromatic contrast, as well as yellow-black gratings of pure luminance contrast. As compared with controls, OAG patients had reduced CS for both luminance and chromatic contrast stimuli by about 6 dB. PERGs and VEPs to luminance stimuli were little affected, whereas those to chromatic stimuli were both reduced in amplitude and delayed. These results indicate that visual dysfunction in glaucoma is not selective for the M-pathway, and that responses to equiluminant colour-contrast stimuli may be of diagnostic value.