29.1 Equipment Maintenance, Calibration, Emergency Equipment & Inventory

The governing principle

The blueprint phrases it precisely: "maintain and calibrate ophthalmic equipment per manufacturer's recommendations." Not per habit, not per what the previous technologist did. The manufacturer's instructions for use define the intervals, the approved cleaning agents and the calibration method, and deviating from them can void warranty, damage the instrument and invalidate results.

Keep a maintenance log for each instrument recording the date, what was done, by whom, and any fault found. That log is what demonstrates due diligence when a measurement is questioned.

Calibration checks the technologist performs

Goldmann applanation tonometer. The most examinable calibration task.

1. Fit the calibration bar (the weighted rod) into its holder on the tonometer.
2. Check at three positions: 0, 2 and 6 — corresponding to 0, 20 and 60 mmHg.
3. At each position, set the drum to the matching value and observe the prism arm. It should just begin to move forward and backward as the drum is moved slightly either side of the setting.
4. Deviation greater than about 0.5 mmHg (some protocols use 2 mmHg at the 6 position) means the instrument requires servicing.
5. Check at least monthly, or per local protocol, and record it.

Also inspect the prism itself for chips, cracks and clouding, and remove damaged prisms from service.

Perimeter. Run the manufacturer's calibration or self-test routine, confirm the bowl illumination and stimulus intensity are within specification, check the bowl surface is clean and free from marks (a smudge becomes a false defect), verify the head and chin rest move freely, and confirm the patient response button works.

Lensometer. The eyepiece is focused by each operator before use — that is an operator step, not a calibration. Verify against a known-power lens periodically. Confirm the marking device deposits three clean dots.

Keratometer. Verify against a calibrated steel ball of known radius supplied with the instrument.

Autorefractor, biometer, pachymeter, topographer and OCT. Run the manufacturer's daily or start-up check where one exists; verify against a test eye or model eye where supplied; and confirm the date and time on the device, because an incorrect timestamp corrupts serial analysis.

Acuity chart or projector. Confirm the test distance is correct and marked on the floor, that the chart luminance is within specification, and that projected charts are focused and square to the wall. A projector at the wrong distance systematically mis-measures every patient in that lane.

Slit lamp. Check bulb function and spare bulbs, beam height and width controls, filters, magnification changer, joystick smoothness and the security of the chin rest and headrest.

Cleaning

Optics — objectives, eyepieces, condensing lenses, mirrors, prisms:

1. Blow off loose debris first with a bulb blower. Wiping grit across a coated lens scratches it permanently.
2. Use only approved lens tissue or a clean microfibre cloth and the manufacturer-approved solution.
3. Wipe in a spiral from the centre outward, with light pressure.
4. Never use acetone, alcohol on coated optics unless approved, household glass cleaner, paper towel or clothing.
5. Never touch optical surfaces with fingers; skin oils etch coatings and appear in every subsequent image.

Mechanical parts — clean and lubricate slides and rails only with the specified lubricant and only where the manual says to. Over-lubrication attracts dust and stiffens the mechanism.

Patient-contact surfaces — chin rests, headrests, handles, occluders and trial frames are disinfected between patients with an approved wipe, and fresh chin rest tissue is used for each patient.

Batteries, bulbs and consumables

Batteries in direct ophthalmoscopes, retinoscopes, transilluminators and hand-held tonometers:

• Rechargeable handles are returned to the charger after each session; running them flat repeatedly shortens their life.
• Replace the whole set of disposable cells at once, never mixing old and new, and never mixing chemistries.
• A dimming or yellowing retinoscope or ophthalmoscope beam is a clinical problem, not a cosmetic one — a weak retinoscope reflex is harder to neutralise and a dim ophthalmoscope misses fundus detail.
• Remove batteries from instruments that will be stored unused, to prevent leakage and corrosion.

Bulbs — keep spares for every instrument in the lane, know how to change each one, and let a halogen bulb cool before handling. Do not touch a halogen bulb with bare fingers: skin oils create a hot spot and shorten its life dramatically. Use a tissue or glove.

Consumables to keep stocked: tonometer tip covers and disposable prisms, fluorescein strips, lens tissue and cleaning solution, chin rest tissue, occluder patches and adhesive occluders, trial lens cleaning supplies, printer paper for perimeters and OCT, batteries, spare bulbs, and personal protective equipment.

Emergency equipment

Maintain emergency equipment is an explicit blueprint task. The technologist contribution is knowing where everything is and checking it on schedule.

Nothing in front of the emergency trolley. The commonest failure at a real emergency is not a missing item but a trolley behind a stack of chairs.

Faulty equipment

1. Take it out of service immediately. Do not leave it for the next user to discover.
2. Tag it clearly — "Out of service, do not use," with the date, the fault and your name.
3. Report it through the correct channel and log it.
4. If a patient was involved in an equipment failure or injury, preserve the device exactly as it is — do not clean, adjust or repair it — and follow the incident reporting process. The device may be evidence.
5. Arrange service, and record the service report when it returns.
6. Verify calibration after any repair before returning the instrument to clinical use.

Inventory and supplies

Order and maintain medical supplies and inventories is a named task. Practical discipline:

• Maintain par levels — a defined minimum stock for each item, triggering a reorder.
• Rotate stock first in, first out, placing new stock behind old.
• Check expiry dates on a schedule, not only when reaching for an item; expired sterile supplies, drops, fluorescein strips and culture media must be removed.
• Store per the label — refrigerated items such as some anaesthetics and fortified antibiotics in a monitored fridge with a temperature log.
• Keep Safety Data Sheets accessible for every hazardous chemical.
• Track controlled or restricted items according to local requirements.
• Note recalls and act on them promptly, removing affected lots and documenting the action.

Patient education materials carry their own inventory task, listed separately in the supplemental testing content area as "order and maintain patient education materials inventory." Treat printed handouts like stock: keep the conditions, procedures and drop regimens the clinic sees most often in stock, check the revision date on each leaflet rather than assuming it is current, withdraw superseded versions the moment a protocol or a drug changes, and hold the languages and large-print formats your patient population actually needs. A leaflet describing a discontinued medication or an out-of-date post-operative regimen is worse than no leaflet, because the patient will follow it.