Effects of Myopia and Glaucoma on the Neural Canal and Lamina Cribrosa Using Optical Coherence Tomography.

PRCIS: Glaucoma was associated with axial bowing and rotation of Bruchs membrane opening (BMO) and anterior laminar insertion (ALI), skewed neural canal, and deeper anterior lamina cribrosa surface (ALCS). Longer axial length was associated with wider, longer, and more skewed neural canal and flatter ALCS. PURPOSE: Investigate the effects of myopia and glaucoma in the prelaminar neural canal and anterior lamina cribrosa using 1060-nm swept-source optical coherence tomography. PATIENTS: 19 control (38 eyes) and 38 glaucomatous subjects (63 eyes). MATERIALS AND METHODS: Participants were imaged with swept-source optical coherence tomography, and the images were analyzed for the BMO and ALI dimensions, prelaminar neural canal dimensions, and ALCS depth. RESULTS: Glaucomatous eyes had more bowed and nasally rotated BMO and ALI, more horizontally skewed prelaminar neural canal, and deeper ALCS than the control eyes. Increased axial length was associated with a wider, longer, and more horizontally skewed neural canal and a decrease in the ALCS depth and curvature. CONCLUSION: Our findings suggest that glaucomatous posterior bowing or cupping of lamina cribrosa can be significantly confounded by the myopic expansion of the neural canal. This may be related to higher glaucoma risk associated with myopia from decreased compliance and increased susceptibility to IOP-related damage of LC being pulled taut.

Visual rehabilitation using microperimetric acoustic biofeedback training in individuals with central scotoma.

BACKGROUND: Patients with central scotoma have poor fixation stability and poor visual acuity. Acoustic biofeedback training can be an effective way to train such patients to eccentrically fixate. This study analyses the mean retinal sensitivity, saccadic velocity, and fixation stability after acoustic biofeedback training and shows correlation with age and scotoma size. METHODS: Patients with irreversible central scotoma in both the eyes secondary to macular diseases were selected. After undergoing comprehensive low vision assessment, 19 patients who were willing were recruited for the acoustic biofeedback training to the better eye in 10 sessions, using the MP-1 Microperimeter. Mean retinal sensitivity, saccadic velocity, fixation stability before and after the acoustic biofeedback were recorded. RESULTS: There were 17 men and two women. Ages ranged from 19-94 years (mean 54.63 ± 24.66). The scotoma size ranged from four to 20 degrees. Ten patients had age-related macular degeneration, four had Stargardt disease, three had traumatic macular scar, two had scarred myopic choroidal neovascular membrane, and one had myopic macular degeneration. The vision improved from 1.06 ± 0.36 to 0.86 ± 0.33 logMAR (p < 0.0001). The mean retinal sensitivity improved from 2.1 ± 2.9 dB to 2.7 ± 3.1 dB (p = 0.01), with negative correlation with age (p = 0.01) and scotoma size (p = 0.02). Fixation stability improved with reduction in the bivariate contour ellipse area (p = 0.01). It showed negative correlation with age (p = 0.02) and scotoma size (p = 0.10). The saccadic velocity reduced from 0.34°/second to 0.26°/second but was not significant (p > 0.99). The majority (58 per cent) had their preferred retinal locus superior to the fovea. There was good agreement between bivariate contour ellipse area and MP-1 Microperimeter inbuilt fixation parameters. The effect was maintained at six months with slight reduction in fixation stability. CONCLUSION: Acoustic biofeedback can improve fixation behaviour, visual acuity and retinal sensitivity in patients with central scotoma. The results are better with younger age and smaller scotoma size.

Effect of sedation on visual sensations in patients undergoing cataract surgery under topical anaesthesia: a prospective randomized masked trial.

PURPOSE: The main aim of the study was to determine whether intravenous sedation with midazolam reduces the ability of patients to see during cataract surgery performed under topical anaesthesia. We also sought to determine the effects of sedation on patient's level of disturbance to the microscope light and visualization of surgical instruments and on the overall of experience of the patients during surgery. METHODS: A total of 78 patients, aged 40-75 years, were randomly divided into two groups: Group S, (sedation) who received intravenous midazolam 0.015 mg/kg, and Group NS, (no sedation) who did not receive midazolam. Patients with history of anxiety, those with history of intraocular surgery and those with severe chronic obstructive pulmonary disease were excluded. Topical anaesthesia was achieved by the application of 2% xylocaine gel over the conjunctiva. A blinded observer interviewed all the patients 30 min after the surgery using a standard questionnaire. RESULTS: Significant number of patients (25.6%) in Group NS was disturbed a lot because of the microscope light compared to Group S (5.1%), p = 0.021. Also, statistically significant number of patients in Group S (48.7%) compared to Group NS (20.5%) was not sure about the images perceived during surgery and were unable to recollect them after the surgery, p = 0.008, and 12.8% of the patients in Group NS reported the visual experience as frightening compared to 2.6% of patients in Group S, p = 0.239. CONCLUSION: Our study confirms that intravenous midazolam reduces both the ability to see and recall intraoperative visual images in patients undergoing cataract surgery under topical anaesthesia.

Toxic optic neuropathy following ingestion of homeopathic medication Arnica-30.

We report a case of acute, bilateral and severe vision loss after inadvertent consumption of a large quantity of the homoeopathic medication Arnica-30. Severe vomiting which required hospitalization preceded visual symptoms. In the acute stage, pupillary responses to light were absent and fundus examination was normal. Vision loss followed a fluctuating course, with profound loss noted after 6 weeks along with bilateral optic disc pallor. Neuro-ophthalmic examination and detailed investigations were performed, including magnetic resonance imaging, electroretinography (ERG) and visual evoked potentials (VEP). Ocular coherence tomography (OCT) showed gross thinning of the retinal nerve fiber layer. While a differential diagnosis of posterior ischemic optic neuropathy was kept in mind, these findings supported a diagnosis of bilateral toxic optic neuropathy. Arnica-30 is popularly used to accelerate wound healing, including after oculoplastic surgery. While homeopathic medicines are generally considered safe due to the very low concentrations involved, Arnica-30 may be neurotoxic if consumed internally in large quantities.