Lost Hearing Aid, Cochlear Implant Processor, or Prescription Glasses in Public, Pond, Snow, or Trash Compactor: Bluetooth RSSI Triangulation¶

When a prescription Hearing Aid (Phonak, Oticon, Starkey, ReSound, Signia, Widex), an external Cochlear Implant Sound Processor (Cochlear Nucleus, Kanso, MED-EL Sonnet/Rondo, Advanced Bionics) costing $3,000 to $10,000, or high-index Prescription Eyeglasses vanish in tall grass, snow, a murky pond, a hospital bed, or a trash chute, you are racing against a dying battery, lawnmowers, trash compactors, and curious pets. However, if a child, an older adult with dementia, or a household dog or cat has just chewed or swallowed a hearing aid or its Zinc-Air / Lithium-Ion button battery, call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) or Poison Control immediately and consult our emergency numbers guide, because an ingested button battery or rechargeable lithium cell burns through the esophagus within 2 hours. For swallowed devices or broken frames, consult our swallowed denture, broken eyeglasses, or hearing aid guide, our hearing aid button battery swallowed by a senior or pet guide, and our button battery leak cleanup guide.

Because modern Behind-The-Ear (BTE), Receiver-In-Canal (RIC), and Cochlear Implant processors transmit continuous 2.4 GHz Bluetooth Low Energy (BLE) advertising packets for 12 to 24 hours on a single charge, the single biggest mistake people make is walking away from the drop zone to look for help, breaking the 10-to-15-meter (33-to-50-foot) Bluetooth radio link before their smartphone can lock onto the live signal. By freezing in place, using your hearing aid app's Received Signal Strength Indicator (RSSI) proximity meter with the "Body-Shielding" directional sweep, and deploying a magnetic sweeping wand to snag a cochlear implant's powerful internal neodymium headpiece magnet, you can pinpoint a tiny flesh-colored device hidden deep inside snow, leaves, or trash bags in minutes.

Do this now¶

1. STOP walking immediately and lock all pets and children out of the search area. Stepping blindly changes a $0 recovery into a crushed $3,000 receiver shell, and dogs are irresistibly drawn to the salty human earwax scent (cerumen) on lost hearing aids, chewing the plastic shell and swallowing the toxic button battery within 60 seconds.
2. Open your manufacturer smartphone app (myPhonak, Oticon Companion, My Starkey, ReSound Smart 3D, Nucleus Smart) BEFORE leaving Bluetooth range. Look first at the Live Signal / Proximity Finder (RSSI meter), not just the GPS street map. The GPS map only shows where your phone was when the connection broke, whereas the Proximity Signal Bar shows live millimeter-wave signal strength if the hearing aid battery is still alive within 10 meters (33 feet).
3. Never turn off your phone's Bluetooth or restart your phone if the hearing aid still shows "Connected." Some hearing aids enter a low-power sleep state if disconnected and will not reconnect until their battery door is physically opened and closed. Keep the live BLE link active while you triangulate.
4. If a Cochlear Implant processor (Nucleus, Kanso, Sonnet, Rondo, Naída CI) is lost in grass, snow, or bedding, sweep the ground with a ferromagnetic steel bar or roofing magnet. Every external cochlear implant transmitter coil (and off-the-ear single-unit processor like Kanso and Rondo) houses a powerful Grade N42-N52 Neodymium-Iron-Boron (NdFeB) magnet designed to lock across the scalp skin. It will jump 3 to 5 centimeters (1.2 to 2 inches) through snow or grass to snap onto a steel skillet, machete blade, or magnetic tool sweeper.
5. If lost inside a hotel, hospital, restaurant, or home trash bin, lock down the dumpster and linen hampers immediately. Over 60 percent of indoor hearing aid losses occur when the user wraps their aids in a paper napkin on a dinner tray or sets them on a pillowcase. Alert housekeeping or restaurant staff immediately to freeze the trash compactor and linen chute.
6. If you recover a hearing aid or cochlear processor from water, snow, or mud, remove the zinc-air battery immediately and NEVER put it in rice or use a hairdryer. Rice starch dust clogs the microscopic 0.1-millimeter acoustic microphone ports (MEMS membranes), and hot air melts the internal acoustic dampers. Use a dedicated silica-gel desiccant drying jar or UV electronic dry-box (Dry & Store / PerfectDry Lux).

Method 1: Rescuing a live hearing aid or cochlear processor via Bluetooth BLE RSSI triangulation¶

Modern hearing aids and cochlear processors communicate with iPhones (MFi - Made for iPhone) and Android phones (ASHA / LE Audio) using 2.4 GHz Bluetooth Low Energy (BLE). Because 2.4 GHz radio waves are heavily absorbed by water (including the human body, wet grass, and snow), a tiny hearing aid lying flat on the ground only has an effective line-of-sight range of 5 to 12 meters (16 to 40 feet) outdoors and 3 to 8 meters (10 to 26 feet) indoors.

Understanding the two modes inside your "Find My Hearing Aid" app¶

How to execute the "Human Body Shielding" RSSI directional sweep¶

When your app shows that you are within 5 meters (16 feet) of your lost hearing aid, the proximity bar often hovers at 60% to 80% without telling you which direction to look (North, South, East, or West). Because a smartphone has an omnidirectional Bluetooth antenna, walking in circles is slow. Instead, use your own body (which is 60% water and blocks 2.4 GHz radio waves by -15 to -25 dBm) as a directional radar shield:

+-------------------------------------------------------------------------+
|       THE "HUMAN BODY-SHIELDING" BLUETOOTH RSSI TRIANGULATION METHOD    |
+-------------------------------------------------------------------------+
|                                                                         |
|   [ LOST HEARING AID ]  ))  2.4 GHz BLE Signal  ))                      |
|                                                                         |
|   POSITION 1 (Facing the Aid):           POSITION 2 (Turned 180° Away): |
|   Phone held against your chest,         You rotate 180° so your torso  |
|   pointing OUTWARD toward the aid.       blocks the path to the aid.    |
|   -> App Signal Bar jumps to HIGH (90%)  -> App Signal drops to LOW (30%)|
|                                                                         |
|   RESULT: The exact direction you are facing when the signal is HIGHEST |
|   (and directly opposite the 180° drop) points straight to the device.  |
+-------------------------------------------------------------------------+

1. Stand still at the spot where your app first detects the live hearing aid (Signal 20-40%).
2. Press your smartphone flat against your chest (sternum) with the screen facing you. Your torso now blocks 2.4 GHz Bluetooth signals coming from behind your back while allowing signals in front of you to hit the phone completely unobstructed.
3. Rotate your body in four slow 90-degree steps (North -> East -> South -> West), pausing for 6 full seconds at each compass point (Bluetooth RSSI meters average packet data over 3 to 5 seconds, so spinning fast will give false readings).
4. Identify the "Null Direction" and "Peak Direction": The direction where the signal bar drops to its lowest reading means the hearing aid is directly behind your back. Turn 180 degrees to face the peak reading, walk 2 steps (1.5 meters) forward, and repeat the 4-way rotation.
5. The Final 1-Meter "Crouch and Cup" Pinpoint: Once the app bar maxes out at 95% to 100%, crouch down and cup both hands tightly around the edges of your smartphone (leaving only the top edge exposed) and sweep it 10 centimeters (4 inches) above the grass, snow, or sofa cushions like a metal detector until you spot the receiver wire.
6. Download a Raw dBm Bluetooth Scanner App if the Manufacturer App Was Never Set Up: What if you never enabled "Location Services" in your hearing aid app before losing it? As long as the hearing aid is still powered on and not actively paired (or is broadcasting BLE advertisements), you can download a free third-party Bluetooth scanner (Wunderfind, LightBlue, or nRF Connect) on any smartphone. It will list every raw BLE radio transmitter within 10 meters and display live decibel-milliwatt (dBm) numbers:
7. -85 dBm to -90 dBm = Far away (8 to 12 meters)
8. -65 dBm to -75 dBm = Getting warm (2 to 5 meters)
9. -35 dBm to -45 dBm = Right under your hand (< 30 centimeters / 1 foot)

Method 2: When the battery is dead (Acoustic, Magnetic, and Optical sweeps)¶

What if the Zinc-Air battery died, the rechargeable lithium cell ran out after 18 hours, or you dropped a pair of non-electronic prescription eyeglasses? Switch immediately to physical physics-based search methods:

flowchart TD
    A["Lost Hearing Aid, Cochlear Processor, or Glasses"] --> B{"What Type of Device Was Lost?"}
    B -- "Hearing Aid or Cochlear Processor (Battery Alive)" --> C["Open Manufacturer App or BLE Scanner (Wunderfind / nRF Connect)"]
    C --> D["Use Human Body-Shielding 4-Way Rotation to Follow RSSI Signal to -40 dBm"]
    B -- "Cochlear Implant Processor or Coil (Battery Dead)" --> E["Sweep Grass, Snow, or Bedding with Magnetic Sweeping Bar or Steel Skillet"]
    E --> F["Internal Neodymium Headpiece Magnet Snaps Onto Steel From 3 to 5 cm Away"]
    B -- "Hearing Aid (Battery Dead or No Bluetooth)" --> G["Check Napkins, Bedding, & Pet Belly First; Listen for 3 kHz Feedback Whistle"]
    G --> H["At Dusk/Dark: Sweep Ground at 15-Degree Grazing Angle with LED Flashlight + Pantyhose Vacuum"]
    B -- "Prescription Eyeglasses (In Grass, Snow, or Pond)" --> I["At Dusk: Shine Horizontal Flashlight Beam Across Ground to Catch AR Lens Glint"]

1. The Magnetic Sweep for Cochlear Implant Processors and Hearing Aid Telecoils/Chargers¶

• Cochlear Implant Processors (Nucleus, Kanso, Sonnet, Rondo, Naída CI): Every cochlear implant external unit contains a powerful permanent rare-earth Neodymium magnet (strength #1 to #6) that holds the coil against the skull. Even if the processor is completely dead, buried under 8 centimeters (3 inches) of snow, or submerged in a muddy puddle, dragging a hardware-store Magnetic Tool Sweeper ($15 rolling magnet bar), a flat carbon-steel frying pan, or a steel garden hoe flush across the grass or snow will physically pull the cochlear processor out of hiding with an audible click.
• Rechargeable Hearing Aids (Magnetic Inductive Contacts) and Zinc-Air Batteries: Most modern rechargeable RIC hearing aids contain tiny alignment magnets in their base (so they snap into their desktop charging ports), and every single Zinc-Air button battery casing (Sizes 10, 312, 13, 675) is made of nickel-plated ferromagnetic steel. A strong Neodymium Fishing Magnet (N52 grade, 50-to-100 kg pull force) swept 2 centimeters above deep carpet, gravel, or leaf litter will snatch any hearing aid containing a button battery right off the ground.

2. The Acoustic Feedback ("Cupped-Ear Whistle") Sweep¶

If an older non-Bluetooth hearing aid is still powered on in a quiet room or flowerbed, acoustic feedback is your best ally: * Turn off all fans, televisions, and refrigerators in the room. * Crawl slowly on hands and knees, holding a flat hardcover book or cardboard box lid 3 centimeters (1 inch) above the carpet or sofa crevices. When a flat reflective surface passes directly over a live hearing aid, sound escaping from the ear dome bounces off the book back into the microphone, triggering a loud, unmistakable 3,000 Hz feedback squeal.

3. The Pantyhose Vacuum-Nozzle Extraction (For Couch Cushions, Car Seats, and Shag Rugs)¶

When a tiny RIC hearing aid or a small eyeglass nose-pad screw drops into the deep abyss of a recliner chair mechanism, car seat track, or thick carpet: * Never vacuum normally (the spinning beater brush will shatter a $3,000 hearing aid shell in 1 second). * Stretch a thin nylon stocking, pantyhose, or cheesecloth over the tip of the crevice wand hose attachment and secure it tightly with a rubber band. * Insert the wand deep under car seats or sofa cushions and turn the vacuum on: suction will pull the hearing aid firmly against the nylon mesh screen so you can lift it out intact.

4. Finding Lost Prescription Eyeglasses (or Hearing Aids) in Grass, Snow, or a Pond¶

Prescription eyeglass lenses are almost invisible in green grass or clear water during midday sun because light passes straight through them. Wait until dusk (or create shade) and use two optical physics tricks: * The 15-Degree Grazing Flashlight Sweep (Catching the Green/Purple Anti-Reflective [AR] Coating): Nearly all modern prescription glasses have a multi-layer metal-oxide Anti-Reflective (AR) coating that reflects a brilliant, unmistakable neon emerald-green, sapphire-blue, or violet glint at specific angles, while metal frames and hearing aid receiver wires glint sharply against dark soil. At dusk, lie your flashlight completely flat on the ground (10 to 15 degrees) and sweep the beam horizontally across the lawn or snow. Any lens, frame hinge, or plastic hearing aid shell protruding 5 millimeters above the surface will cast a long shadow and flash brightly. * Looking Through a Smartphone Camera or Polarized Sunglasses into a Pond: If glasses or a hearing aid dropped into shallow pond or creek water (0.3 to 1.5 meters deep), do not stir up the mud with your boots. Put on polarized sunglasses to cut 90 percent of surface sky glare, or submerge a waterproof smartphone (IP68) 5 centimeters below the water surface with the Video Camera + LED Torch turned ON to inspect the bottom with zero surface refraction. For metal eyeglass frames or a cochlear processor in murky water, tie a nylon cord to a Neodymium magnet or a heavy garden rake wrapped in plastic poultry netting and drag it gently along the bottom.

Trash chute, dumpster, and hospital laundry recovery protocol¶

More than half of all indoor hearing aid and eyeglass losses occur in hospitals, nursing homes, hotels, and restaurants when devices are wrapped in a meal tray napkin or tangled in bedsheets.

1. Freeze the chain of custody in the first 5 minutes:
2. In a hospital or nursing home: Alert the charge nurse and dial Environmental Services (EVS) / Housekeeping AND Dietary Services simultaneously. Bedsheets go to central laundry chutes in color-coded bags, while meal trays go to the dish-room conveyor belt. Stopping the room's linen bag or dietary cart before sorting yields an 85 percent recovery rate.
3. In an apartment or hotel trash compactor: Immediately ask the superintendent or front desk manager to shut off the breaker on the trash chute compactor.
4. Bag-by-Bag Bluetooth + Magnetic Triage (Without Ripping Open Every Bag):
5. Line the sealed trash or linen bags up 2 meters (6 feet) apart down a hallway rather than dumping garbage on the floor.
6. Walk slowly down the row holding your smartphone with the Hearing Aid Proximity App (or Wunderfind BLE scanner) against each bag for 8 seconds to identify the single bag broadcasting a signal.
7. For a Cochlear Implant processor in linen bags, sweep a strong magnet around the outside of each bag, the headpiece magnet will snap through the fabric. Wear puncture-resistant gloves when sorting any target trash bag.

Wet recovery care: how to dry a waterlogged hearing aid or cochlear processor safely¶

Modern hearing aids (IP68 rated) and water-resistant cochlear processors survive brief freshwater submersion (up to 1 meter for 30 to 60 minutes) provided you do not ruin them during drying.

The 5 rules of wet hearing aid & cochlear processor salvage¶

1. Power off and open the battery door within 10 seconds:
2. Zinc-Air Disposable Battery Models: Pop the battery door open, remove and discard the wet Zinc-Air battery immediately (wet zinc-air cells swell and leak potassium hydroxide within 30 minutes), and leave the door open.
3. Sealed Rechargeable Lithium-Ion Models: Turn the hearing aid OFF immediately via the button or app. Never place a wet rechargeable hearing aid into its electric charger, as live current causes immediate electrolytic pin corrosion.
4. Wipe clean if submerged in saltwater, pool water, or mud:
5. Saltwater or mud left to dry leaves conductive crystals inside microphone ports. Wipe the exterior gently with a lint-free cloth moistened with clean water (never submerging an open battery door), then blot dry with a microfiber towel.
6. NEVER use uncooked rice, a hairdryer, a microwave, or an oven:
7. Why rice ruins hearing aids: Uncooked white rice sheds microscopic starch dust (10 to 50 microns) that enters the 0.1-millimeter microphone inlets (MEMS ports), mixes with moisture, and hardens into solid starch paste across the microphone diaphragm, permanently deafening the device.
8. Why hairdryers ruin hearing aids: Hairdryers blast air at 60 to 80 degrees Celsius (140 to 176 degrees Fahrenheit), melting thermoplastic receiver tubing, warping acoustic seals, and blowing water droplets deeper past the hydrophobic microphone membrane.
9. Use a Dedicated Desiccant Jar or Electronic UV Dryer (Dry-Aid / Zephyr / PerfectDry):
10. Place the open device (disposable battery removed or rechargeable unit powered off, ear dome detached) inside a Silica Gel Desiccant Jar or convection hearing aid dryer (35 to 40 degrees Celsius max) for 12 to 24 hours.
11. Household Substitute: Seal 3 or 4 clean Silica Gel packets (from vitamin bottles or shoe boxes, kept strictly away from pets and children) inside an airtight Ziploc bag or mason jar with the open hearing aid at room temperature (22 degrees Celsius / 72 degrees Fahrenheit) overnight.
12. Replace the Wax Guard (Cerumen Filter):
13. A dried hearing aid often sounds dead simply because wet earwax inside the tiny white plastic Wax Filter (Cerustop, ProWax, NanoCare) at the speaker tip has swollen into an airtight plug. Pull the rubber dome off, swap in a new wax filter, and test the sound.

Emergency backup workarounds when glasses or hearing aids cannot be found¶

1. The Emergency "Pinhole Occluder" for Lost Prescription Eyeglasses¶

If you have severe myopia (-4.00 D to -10.00 D), hyperopia, or astigmatism and lose your glasses while traveling, you can restore sharp 20/30 reading and sign-reading vision in 10 seconds using pinhole optics: * How it works: Looking through a 1.0-to-1.5-millimeter pinhole blocks unfocused peripheral light rays and allows only straight central axial rays to hit the retina, creating an infinite depth of field regardless of prescription. * How to do it: Poke a 1-millimeter hole through an index card or piece of aluminum foil with a pin (or curl your index finger into a tiny 1-millimeter tunnel) and peer through it with one eye closed to read signs or phones. Alternatively, hold your smartphone camera screen 8 centimeters (3 inches) from your nose with the rear camera video on to view distant objects in sharp focus. (Never drive using a pinhole occluder).

2. Turning Your Smartphone and Earbuds into an Emergency Personal Amplifier¶

If an older adult loses their hearing aids before a critical appointment or during a hospital stay: * On Apple iPhone (iOS): Pair AirPods or plug in wired earbuds, open Settings -> Control Center -> Hearing (Ear Icon), and enable Live Listen. Place the iPhone near the speaker to amplify their voice up to +30 dB. * On Android (Pixel / Samsung): Open Settings -> Accessibility -> Hearing Enhancements -> Sound Amplifier with wired or Bluetooth headphones to boost speech frequencies.

Manufacturer loss-and-damage replacement warranties (1-time deductible rules)¶

Never pay full retail price ($3,000 to $6,000) to replace a lost device before checking three coverage layers:

1. Manufacturer Loss & Damage (L&D) Warranty (First 1 to 3 Years): Major hearing aid brands (Phonak, Oticon, Starkey, ReSound, Signia, Widex) and cochlear implant makers (Cochlear, MED-EL, Advanced Bionics) include a One-Time Loss and Damage Replacement Warranty during the initial 1-to-3-year warranty (up to 5 years on pediatric/Medicare cochlear processors). For a modest clinic deductible ($150 to $400), the manufacturer provides an identical programmed replacement.
2. Important Rule if a Dog Chewed the Hearing Aid: Collect all chewed plastic fragments and the receiver wire in a bag (after confirming the battery was not swallowed) and hand them to your audiologist. Returning a damaged unit is processed as a Warranty Repair/Remake (often $0), preserving your One-Time Loss Replacement for the future.
3. Credit Card & Homeowner Insurance Riders: Check credit card 90-to-120-day purchase protection or homeowner/renter $0-deductible Medical Device personal property floaters.

Global emergency numbers and poison / veterinary hotlines¶

• United States and Canada: For human button-battery or hearing aid ingestion, call 911, Poison Control (1-800-222-1222), or the National Battery Ingestion Hotline (1-800-498-8666) immediately. For a pet that swallowed a hearing aid, go to an emergency vet or call the ASPCA Animal Poison Control Center (1-888-426-4435) or Pet Poison Helpline (1-855-764-7661).
• United Kingdom: Call 999 for human battery ingestion. For lost NHS Hearing Aids or NHS Cochlear Processors, contact your hospital NHS Audiology Department for replacement. For pet ingestion, call your emergency vet or the Veterinary Poisons Information Service (VPIS).
• European Union: Call 112 for battery ingestion emergencies, and contact your audiology clinic or statutory health insurer (Krankenkasse / Assurance Maladie) for replacement coverage.
• Australia and New Zealand: Call 000 (Australia), 111 (NZ), or the Poisons Information Centre (13 11 26 AU / 0800 764 766 NZ) for battery ingestion. Eligible pensioners under the Australian Government Hearing Services Program (HSP) receive statutory lost-device replacements for a small regulated fee.
• Asia (Japan, Singapore, South Korea, India): Call 119 (Japan/South Korea), 995 (Singapore), or 112 (India) for battery ingestion emergencies.

First aid education note: Taking a first aid course through the Red Cross or St John Ambulance teaches button-battery honey administration rules (10 mL of honey every 10 minutes for humans over 12 months old en route to the ER; prioritize immediate veterinary X-ray removal for pets).

Frequently asked questions¶

How does the "Find My Hearing Aid" app work if my hearing aid does not have a built-in GPS chip?¶

Prescription hearing aids are far too small to house a power-hungry satellite GPS chip. Instead, your manufacturer smartphone app works in two separate ways: first, it uses your smartphone's GPS to drop a map pin at the exact street location where your phone last had an active Bluetooth connection with the hearing aid. Second, once you walk back within 5 to 12 meters (16 to 40 feet) of the lost hearing aid, the app's Proximity Finder (`RSSI` signal bar) measures the live 2.4 GHz Bluetooth Low Energy (`BLE`) signal strength radiating from the hearing aid itself, allowing you to play "hot and cold" until you find it.

How can I tell which direction to walk when the Bluetooth hearing aid finder bar is at 50%?¶

Because the human body is roughly 60 percent water and strongly absorbs 2.4 GHz Bluetooth radio waves, you can use your own torso as a directional radar shield. Hold your smartphone flat against your chest facing outward and rotate in four slow 90-degree steps (`North, East, South, West`), pausing for 6 seconds at each direction so the signal meter can update. The direction where the signal bar drops to its lowest point means your back is blocking the hearing aid; turn 180 degrees to face the highest signal reading and walk two steps forward.

Why did a magnet pull my lost Cochlear Implant processor right out of the snow?¶

Every external Cochlear Implant sound processor coil (and off-the-ear processors like the Cochlear Kanso or MED-EL Rondo) houses a powerful permanent rare-earth Neodymium magnet inside the headpiece that locks it across the skin to the internal surgical implant. Even if the processor battery is completely dead, sweeping a hardware-store magnetic tool bar, a strong neodymium magnet, or a flat carbon-steel frying pan within 3 to 5 centimeters (1 to 2 inches) of grass, snow, or bedding will cause the processor to snap directly onto the metal.

What should I do if I suspect my dog ate my lost hearing aid?¶

Dogs are strongly attracted to the smell of human earwax and frequently swallow hearing aids whole in seconds. Before searching the house, hold your smartphone with the hearing aid Bluetooth app open directly against your dog's abdomen to see if the signal spikes to 100%, and listen to the dog's belly for a high-pitched feedback whistle. If the signal comes from the dog, or if you find chewed plastic bits with the Zinc-Air or Lithium-Ion battery missing, take the dog to an emergency veterinarian immediately for an X-ray and endoscopic removal before battery acid burns through the stomach.

Why should I never put a wet hearing aid or cochlear processor in a bowl of uncooked rice?¶

Uncooked white rice is covered in fine microscopic starch dust that floats into the tiny `0.1-millimeter` acoustic microphone ports of a wet hearing aid, mixes with moisture, and hardens into solid starch paste on the microphone membrane, permanently destroying sound quality. In addition, rice absorbs ambient moisture poorly compared to real desiccants. Always remove the disposable battery immediately, blot the exterior dry, and place the device in a dedicated hearing aid UV/desiccant dryer or a sealed jar containing clean silica gel packets at room temperature.

How can I see well enough to get home safely if I lose my strong prescription glasses?¶

You can temporarily restore surprisingly sharp `20/30` focal vision without lenses by using pinhole optics: poke a tiny `1-millimeter` hole through an index card, business card, or piece of aluminum foil with a pin (or curl your index finger into a tiny `1-millimeter` tunnel) and look through the hole with one eye closed. The tiny aperture blocks unfocused peripheral light rays and allows only straight central rays to hit your retina. If you are severely nearsighted, you can also turn on your smartphone's camera and hold the screen 8 centimeters (3 inches) from your nose to view distant signs clearly.

Related guides¶

• Hearing Aid Button Battery Swallowed by a Senior with Dementia or Pet
• Swallowed Denture, Crown Inhalation, and Broken Eyeglasses or Hearing Aid
• Phone or Keys Dropped Down a Storm Drain, Elevator Shaft, or Portable Toilet
• Broken Compact Fluorescent Bulb, Mercury Thermometer, or Button Battery Leak Cleanup
• Engagement Ring or Valuable Washed Down Sink Drain: P-Trap Bucket Catch

Sources and official guidance¶

• National Capital Poison Center / National Battery Ingestion Hotline (United States): Clinical Triage Guidelines for Human and Veterinary Ingestion of Hearing Aid Button Batteries and Rechargeable Lithium Cells.
• American Speech-Language-Hearing Association (ASHA) and American Academy of Audiology (AAA) (United States): Patient Guidance on Bluetooth Low Energy (BLE) Hearing Aid Geolocation, Moisture Care, and Loss Prevention.
• Royal National Institute for Deaf People (RNID) and British Society of Audiology (BSA) (United Kingdom): NHS and Private Hearing Aid Care, Drying Protocols, and Replacement Guidelines.
• Cochlear Limited / MED-EL / Advanced Bionics Clinical Technical Manuals: IP68 Water Resistance Ratings, Neodymium Coil Magnet Safety, and Desiccant Drying Specifications.
• American Academy of Ophthalmology (AAO) (United States): Clinical Optics of the Pinhole Occluder Test for Uncorrected Refractive Error.