Transcranial Direct Current Stimulation in Children With Anisometropic Amblyopia.

BACKGROUND: Amblyopia is defined clinically as a difference in best-corrected visual acuity of two or more lines of acuity (0.2 logMAR) between the eyes. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that can transiently alter the excitability of targeted brain areas in a polarity-specific manner. PURPOSE: To detect the effect of tDCS on anisometropic amblyopia. METHODS: This is a randomized controlled trial conducted on 78 patients with anisometropic amblyopia from 4.5 to 12 years of age. All patients presented with monocular amblyopia. They were divided into three groups; each group received five sessions of tDCS (anodal tDCS, cathodal tDCS, and sham tDCS). The active electrode was placed over occipital midline and the reference over central midline. Pattern visual-evoked potentials and contrast sensitivity tests were conducted before, immediately after, and 1 week after tDCS. RESULTS: The amplitude of P100 was significantly decreased immediately after and 1 week after cathodal tDCS. The latency of P100 immediately after and 1 week after anodal tDCS was significantly decreased and increased significantly after cathodal tDCS. The amplitude of P100 and maximum and minimum contrast sensitivities were significantly increased immediately after and 1 week after anodal tDCS, and maximum contrast sensitivity was significantly decreased immediately after cathodal tDCS. CONCLUSION: Anodal tDCS is a promising noninvasive modality for improvement of anisometropic amblyopia.

Role of pattern electroretinogram in assessment of retinal dysfunction in hypertensive patients.

BACKGROUND: Hypertension is a major health problem in both developing and developed countries. Hypertension causes retinal structural and functional impairment within the ganglion cell layer. Pattern electroretinogram (PERG) offers an objective simple tool for assessment of retinal ganglion cell function.Aim of the work: To assess retinal dysfunction in hypertensive patients with or without signs of retinopathy using PERG. MATERIALS AND METHODS: This is a case control study, including ninety-eight eyes. Twenty-eight eyes of healthy subjects served as a control group (group I) and seventy eyes of patients with systemic hypertension, who were further subdivided into group II including 39 eyes of hypertensive patients with normal fundus and group III including 31 eyes of patients with signs of hypertensive retinopathy. All subjects were subjected to ophthalmological examination and electrophysiological assessment using PERG. RESULTS: PERG implicit times were significantly prolonged and amplitudes were significantly reduced in patients with established hypertensive retinopathy. PERG abnormalities were detected in 96.8% of hypertensive retinopathy patients and 79.5% of hypertensive patients with normal fundus. CONCLUSIONS: PERG can objectively assess retinal dysfunction in hypertensive patients and may be considered a promising tool for early detection of hypertensive retinopathy.

Role of multifocal electroretinogram in assessment of early retinal dysfunction in hypertensive patients.

PURPOSE: To investigate localized retinal dysfunction in hypertensive patients using multifocal electroretinogram (mfERG) and to assess its sensitivity as an early predictor for the development of retinopathy in hypertensive patients. METHODS: Ninety-eight eyes were included in this case-control study. Twenty-eight eyes of healthy subjects served as a control group (group I). Seventy eyes belonged to patients with systemic hypertension assigned into two groups; group II including 39 eyes of hypertensive patients with normal fundus and group III including 31 eyes of patients with signs of hypertensive retinopathy. All participants were subjected to complete ophthalmic and electrophysiological examination using mfERG. N1 and P1 wave amplitudes and implicit times from the central hexagon and four concentric rings across the visual field were analyzed. RESULTS: mfERG amplitudes were significantly reduced in hypertensive group with retinopathy than in controls. N1 amplitude was significantly reduced in the most eccentric ring in eyes of hypertensive patients with normal fundus. CONCLUSION: mfERG is a sensitive objective tool for assessment of retinal dysfunction in hypertensive patients. mfERG amplitude is a promising predictor for early development of retinopathy in systemic hypertension.