Visual Fields PPO2_2024.pdf

Visual Fields Ariette Acevedo, O.D. PPO2 Visual Pathway Great majority of visual field defects (VFD) begin in the central visual field, which is within 30 degrees of central fixation. Central Visual Field: ⚬ Central 30 degrees ⚬ Highly developed area of the retina responsible for detailed vision ￭ R...

Visual Fields Ariette Acevedo, O.D. PPO2 Visual Pathway Great majority of visual field defects (VFD) begin in the central visual field, which is within 30 degrees of central fixation. Central Visual Field: ⚬ Central 30 degrees ⚬ Highly developed area of the retina responsible for detailed vision ￭ Reading, color vision, details, recognition Peripheral Visual Field: ⚬ Specialized in the detection of motion signals ￭ Driving, enables safe navigation around our environment Visual Pathway A single eye’s visual field has a normal range of 130° to 145°. Each eye has a physiological blind spot corresponding to the optic nerve. ⚬ 15 degrees temporal and 5 degrees inferior from central fixation. Visual Pathway Visual Field Evaluation Visual field loss or defect may be the only or the most obvious sign that a there is a lesion present in the visual pathway. Visual field defects may present due to: ⚬ Ocular, systemic or neurological disease ⚬ Medications All basic optometric exams should include some form of VF evaluation. ⚬ Visual field screening test can be done quickly and with minimal equipment Visual Field Evaluation For certain conditions it is standard of care. ⚬ Glaucoma: used for diagnostic decisions and monitoring progression. ⚬ Choroid or retinal conditions: even though most are seen in ophthalmoscopy. As a screening tool the practitioner can perform: ⚬ Confrontation Visual Fields (CVF)/Finger Counting Fields (FCF) If suspected of having a VFD or need to perform a more detailed VF evaluation: ⚬ Tangent Screens ⚬ Automated Perimetry Confrontation Visual Fields Equipment: ⚬ Occluder ⚬ Overhead Lamp Set up: ⚬ Dimly illuminated room ⚬ The overhead lamp should be placed between the examiner and the patient. ⚬ Sit facing the patient at eye level at a distance of 60 to 80 cm from the patient. ⚬ Without spectacles Confrontation Visual Fields Occlude patient’s left eye Instruct the patient that you are going to show them 1, 2 or 4 fingers. ⚬ Do not use 3 as it can easily be confused with 2 or 4. Ask the patient to tell you how many fingers you are holding up, while looking at your (examiners) left eye at all times. ⚬ “Le voy a mostar 1,2 o 4 dedos, mirando mi ojo izquierdo en todo momento digame cuantos dedo le muestro.” As the examiner, close your right eye and place your closed fist in the peripheral visual field. ⚬ Use your peripheral field to identify the limits of where to place your hand. ⚬ In Confrontation VF the patients VF is compared to the examiners VF which is presumed to be full. Confrontation Visual Fields Expose 1, 2 or 4 fingers, without wiggling or moving the fingers. Your hand has to be static. ⚬ Make sure the fingers are illuminated and that they are not pointing at the patient ⚬ Place the fingers midway between the patient and yourself Repeat the above step in all 8 VF locations: ⚬ S, SN, N, IN, I, IT, T, ST After the right eye has been evaluated, repeat the procedure with the left eye. ⚬ Have the patient occlude their right eye. ⚬ Fixate on your right eye and close your left eye. During the testing procedure monitor the patients fixation and keep reminding them to fixate on your open eye. Recording FCF/CVF: Full to Finger Counting (FTFC) FCF/CVF: Full Fields to Four Quadrants (FFFQ) FCF/CVF: Full OD/OS If not full, report which areas are restricted. ⚬ OD: FTFC, OS: temporal restriction ⚬ Drawings of constrictions Expected Findings: Full visual field in OD and OS Perimetry vs Campimetry Perimetry: measurement of the visual field where the eye is located at the center of a curved instrument and the targets are projected in an automated form. ⚬ Humphrey Automated Visual Field Campimetry: measurement of the visual field where the eye is located a certain distance from a flat instrument and targets are presented. ⚬ Tangent Screen Tanget Screen Visual Field Defects Terminology Scotoma Hemianopsia or Hemianopia Quadrantanopsia or Quadrantanopia Altitudinal ⚬ Superior or Inferior Homonymous vs. Heteronymous Congruent vs. Incongruent Binasal/Bitemporal Depression or Constriction Visual Field Defects Terminology Congruous (symmetric): the VFD is of the same size and shape in both eyes. Incongruous (asymmetric): the VFD is not of the same size and/or shape in both eyes. Quadrantanopia: loss of ¼ VF of one or both eyes. Altitudinal defects: above or below the horizontal meridian. ⚬ Associated with ocular abnormalities. Homonymous: corresponding visual fields of the two eyes are affected. Left or Right: in respect to the vertical meridian Superior or Inferior: in respect to the horizontal meridian Visual Field Defects Terminology Depression/Constriction: ⚬ A general reduction in overall sensitivity of the visual field. ⚬ Depending on the testing method used it will be termed a constriction or a depression. Constriction/Restriction can be described when evaluating with confrontation VF. Generalized depression can be described when evaluating with a quantitative method, such as Humphrey. ⚬ Can be an early sign of glaucoma, but may also occur with aging, miosis or hazy media. Automated VF compares the results with the population of the same age and will provide the mean deviation from the normal population. Visual Field Defects Terminology Constriction Depression Visual Field Defects Terminology Homonymous: refers to corresponding visual fields in the two eyes or the corresponding parts of the visual pathways. ⚬ Affects the corresponding visual fields of the two eyes. Example: affects the same half (either left or right) of the visual field in each eye. Homonymous Incongruous Defect Homonymous Congruous Defect Visual Field Defects Scotoma: a VFD contained in an area within the boundaries of the overall visual field. ⚬ Area of depressed vision in the VF, surrounded by an area of less depressed or normal vision. Scotomas Shallow or Relative: ⚬ Marks an area of retina that is not sensitive to relatively dim stimuli but is sensitive to brighter/larger stimuli. ⚬ Patient has reduced sensitivity ⚬ The area is perceived as blurry by the patient Deep or Absolute: ⚬ No response to a stimuli regardless of brightness or size (definite absence of processing from this area). ⚬ Refers to a defective retinal area that cannot see. ￭ Example: physiologic optic nerve Scotomas Hemianopic Scotoma: half of the central visual field is depressed or lost. Annular (ring) Scotoma: circular area of depressed vision surrounding the point of fixation. ⚬ Trial lens ring Central Scotoma: an area of depressed vision corresponding with the point of fixation and interfering with central vision. Ceco-central Scotoma: a horizontal oval defect in the field of vison situated between and embracing both the point of fixation and the blind spot. Peripheral Scotoma: visual field defect distance from the fixation point. Scotomas Scotomas Paracentral Scotoma: visual field defect around or near the central vision. ⚬ ARMD, Exudates, early glaucomatous VFD Peri-central Scotoma: a ring scotoma surrounding a normal fovea. ⚬ Plaquenil toxicity can cause this scotoma Visual Pathway Review Visual Field Defects Visual field loss is related to the anatomy of the visual pathway. Visual pathway lesion anterior to the optic chiasm (prechiasm) will produce a monocular ipsilateral defect. ⚬ Ex: macular hole, retinal detachments, glaucomatous changes**, optic atrophy or optic neuropathy. ⚬ If OS optic nerve lesion = VFD in the OS only. Visual Field Defects Chiasm lesions: if the lesion is in the center of the chiasm (mid-optic chiasm) this will produce a bitemporal hemianopsia. Close to the chiasm lies the pituitary gland and there is significant vasculature surrounding it. If a patient presents with a bitemporal hemianopsia rule out: ⚬ Tumor compressing pituitary gland (most common adenoma) or aneurysm of the anterior communicating artery. Visual Field Defects Post chiasm defects: the visual loss will present on the opposite side of the lesion (contralateral) due to the fiber crossing at the chiasm. Any damage to the visual pathway behind the optic chiasm most often produces VFD in the left or right side of vision which affect both eyes. Visual Field Defects Right complete homonymous hemianopsia: ⚬ It affects the right side of both visual fields (homonymous) ⚬ It is a complete loss of half of the visual field (hemianopsia) ⚬ Most common cause is a stroke in the left side of the brain. ￭ Right sided defect, left sided lesion. Visual Field Defects Defects identified as superior, or inferior are referred to as altitudinal defects. Pre-chiasmal altitudinal defects generally respect the horizontal meridian. ⚬ Glaucoma Post-chiasmal altitudinal defects generally respect the vertical meridian. Visual Field Defects-Location 1.ON lesion will cause partial or total loss of vision and VFD of that eye (monocular-ipsilateral) 2.A lesion to the proximal fibers of an ON and the nasal fibers of the opposite eye (before central chiasm), will cause a central VFD in one eye and a partial temporal VFD on the opposite eye (Junctional scotoma) 3.Lesion in the center of the chiasm will cause a bitemporal hemianopsia 1 2 3 Visual Field Defects-Location A lesion to the optic tract or a lesion that involves the complete optic radiations will cause a homonymous hemianopsia. Optic radiations with lesions in: ⚬ Parietal lobe will cause an inferior quadrantanopsia (pie in the floor) ⚬ Temporal lobe will cause a superior quadrantanopsia (pie in the sky) Visual Field Defect Generalized depression is seen in cataracts, early glaucoma. Central VFD is seen in optic neuritis, macular hole, cone dystrophy, BRAO, BRVO. Peripheral VFD can be seen in retinitis pigmentosa, BRVO, BRAO, hysterical amblyopia, Streff Syndrome. Hemianopia and quadrantanopia can be seen with strokes (CVA), traumatic brain injury (TBI), intracranial mass. Altitudinal VFD can be seen in anterior ischemic optic neuropathy (AION), compressive neuropathy (due to a tumor or aneurysm), BRAO, BRVO, papilledema, disc edema. Practice