Trans-orbital sonography versus visual evoked potentials in acute demyelinating optic neuritis.

Optic neuritis (ON) is an inflammatory demyelinating condition that causes acute - usually monocular - visual loss. It is highly associated with multiple sclerosis (MS). In general, ON is a clinical diagnosis based upon the history and examination findings. OBJECTIVE: The aim was to assess the diagnostic accuracy of measuring optic nerve sheath diameter (ONSD) by ultrasound in acute optic neuritis. METHODS: This is a prospective observational study with matched controls carried out on 25 patients and 25 controls. All patients presented with first attack of an acute demyelinating ON. Both patients and controls were submitted to clinical assessment, pattern and flash visual evoked potential and trans-orbital sonography (TOS) to measure the optic nerve sheath diameter (ONSD). RESULTS: The ONSD was significantly thicker in patients with unilateral (0.6 ± 0.05 cm) and bilateral (0.6 ± 0.1 cm) optic neuritis compared to controls (0.52 ± 0.06 cm). P-value was < 0.001 and 0.04 respectively, with a cutoff value 0.57 cm. A significant negative correlation was found between the thickness of the ONSD and the visual acuity (r= -0.613, P-value <0.05). No correlation was found between the age of the patients and ONSD or between ONSD and latency of P-VEP. TOS showed 68% sensitivity and 88% specificity in diagnosing cases of ON. CONCLUSION: ONSD measured by TOS is a noninvasive, inexpensive bed-side test, which represent a supporting tool to confirm the clinical diagnosis of ON. Yet its sensitivity and specificity are lower than P-VEP.

Subthreshold diode-laser micropulse photocoagulation as a primary and secondary line of treatment in management of diabetic macular edema.

BACKGROUND: The purpose of this study was to evaluate subthreshold diode-laser micropulse (SDM) photocoagulation as a primary and secondary line of treatment for clinically significant diabetic macular edema (CSDME). METHODS: In this prospective nonrandomized case series, 220 cases of nonischemic CSDME were managed primarily and secondarily by SDM photocoagulation on a 15% duty cycle with a mean power of 828 mW and a spot size of 75-125 µm. SDM treatment was repeated at 3-4-month intervals if residual leakage was observed. Additional intravitreal pharmacologic therapy was used according to the response. Follow-up varied from 12 to 19 (mean 14±2.8) months. Novel software designed by the authors was used to record the subvisible threshold laser applications and their parameters on the fundus image of the eye. Evaluation of the results of treatment was done using fluorescein angiography and optical coherence tomography (OCT). Primary outcome measures included changes in visual acuity and foveal thickness at OCT. Secondary outcome measures included visual loss of one or more Snellen lines and laser scars detectable on fundus biomicroscopy or fluorescein angiography. RESULTS: In the primary treatment group, there was significant improvement or stabilization of visual acuity after the first 3-4 months, which was stable thereafter. Visual acuity was stable in the secondary treatment group. A corresponding reduction of macular thickness on OCT was noted during the follow-up period in both groups. Additional therapy included repeat SDM photocoagulation, intravitreal injection of triamcinolone, and pars plana vitrectomy. Laser marks seen as changes in retinal pigment epithelium on fundus biomicroscopy and fluorescein angiography were noted in 3.3% and 5.7% of cases. Our novel software could accurately record the location of all SDM-invisible applications. CONCLUSION: Micropulse laser is an effective minimal intensity therapy that offers the clear advantage of minimizing or avoiding laser-induced visible retinal burn/scarring while reducing the foveal thickness in the management of selected cases of CSDME. Future prospective studies should include the use of SDM photocoagulation as a combined minimally invasive therapy to consolidate the prompt but temporary effects of anti-vascular endothelial growth factor or anti-inflammatory agents. Virtual localization of SDM-invisible applications using our proprietary software could be used to guide further retreatments.