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ENT, Ophthalmic & Sensory
Visionstar LS-16

✓ Certified Professional Seller

Visionstar ENT, Ophthalmic & Sensory

Visionstar LS-16

Product Code: EOAS-ECA-3673

Sixteen prisms span ½ to 50 Δ in one aluminium case.

Cover the full measuring range with a short list of prisms: sixteen acrylic prisms from ½ to 50 Δ, each 37 × 37 mm, plus a red filter lens, set in two rows in an aluminium case with a red-lined lid.

Sections

Examination Lenses & Racks

Categories

ENT, Ophthalmic & Sensory

Condition

New

Origin

China

Seller Type

Certified Professional Seller

CE & ISO Certified

Global Shipping

Supplier: Medigear

From Visionstar, the LS-16 loose prism set holds sixteen acrylic prisms of ½, 1, 2, 4, 6, 8, 10, 12, 15, 20, 25, 30, 35, 40, 45 and 50 Δ, each listed at 37 × 37 mm. With one red filter lens the datasheet totals 17 pieces, and the count agrees with the list. The prisms are packed in an aluminium case, which the photograph shows with a red-lined lid, two clasps and the prisms standing in two rows. Calibration position, case dimensions, weight and power marking are not published.

The set reaches 50 Δ with few pieces, and the values it leaves out are the argument. There is no 3, 5, 7, 9, 11, 13 or 14 Δ prism, nothing between 15 and 20 Δ, and steps above 20 Δ are 5 Δ apart. An angle that falls between two prisms is recorded as a bracket, for example between 8 and 10 Δ. At large angles that costs little, because published repeatability of the prism cover test is about ±10 Δ. At small angles, where 2 Δ steps matter more, it is a real limitation, and a practitioner running fine prism trials for diplopia or decompensated phorias will feel the missing odd values most.

The red filter lens can help a patient with diplopia identify which image belongs to which eye, though the datasheet does not state its intended use.

Medigear.uk lists the LS-16 and can arrange delivery worldwide. Request the calibration position, power and base marking, case dimensions and declaration of conformity from the seller before order.

Orthoptic departments use loose prisms for the prism cover test, and this set reaches 50 Δ in single prisms, covering large infantile and sensory deviations without combining prisms before one eye. Above 20 Δ the 5 Δ steps sit within the normal variation of the test, so bracketing between prisms costs little.

Outreach and peripatetic orthoptic services carrying equipment between hospital sites, community clinics and schools can take a case holding sixteen prisms and a red filter, with enough range for most measurements at a second site.

Strabismus surgery planning uses the largest reliable angle at distance and near. Holding a single prism in its confirmed calibration position avoids stacking error, and for angles beyond 50 Δ prism can be divided between the eyes.

Neuro-ophthalmology clinics assessing acquired diplopia can use the red filter to identify which image belongs to which eye, and the low prisms to measure small vertical and horizontal deviations.

Optometry practices with a binocular vision interest can measure phorias and fusional reserves with the ½ to 10 Δ prisms, bearing in mind that values such as 3, 5, 7 and 9 Δ are not included.

Teaching clinics can use the set to show students how bracketing is recorded and why stacking prisms before one eye is avoided.

The set is less suited to services that run frequent small-angle prism trials needing every whole value, and to buyers who need documented calibration without first confirming it. Institutional buyers commonly ask for evidence of conformity. The conformity documentation those procurement routes require is issued by the manufacturer and provided by the seller.

Full Range in Sixteen Prisms

Single prisms run from ½ to 50 Δ, so the whole measuring range fits in one compact case.

Large Angles Without Stacking

Prisms up to 50 Δ neutralise large deviations in one piece, avoiding the errors of stacking.

Steps That Match Test Variation

Above 20 Δ, 5 Δ steps fall within the published repeatability of the prism cover test.

Fine Values at the Bottom

Half, 1 and 2 Δ prisms suit small deviations and the start of fusional reserve measurements.

Red Filter Included

A red filter lens supports simple diplopia assessment.

Square 37 mm Faces

Each prism is listed at 37 × 37 mm, easy to hold and position before either eye.

Aluminium Case

A rigid case with two clasps and a red-lined lid protects the prisms in storage and transit, per the photograph.

No Electrical Upkeep

The set has no electrical parts, needs no mains supply and never enters a portable appliance testing schedule.

Powers

½, 1, 2, 4, 6, 8, 10, 12, 15, 20, 25, 30, 35, 40, 45 and 50 Δ.

Values Not Included

3, 5, 7, 9, 11, 13, 14, 16 to 19 Δ, and values between the 5 Δ steps above 20.

Prism Count

Sixteen.

Red Filter

One red filter lens.

Total Pieces

Seventeen, per the datasheet.

Prism Size

37 × 37 mm.

Material

Acrylic.

Case

Aluminium, per the datasheet. Red-lined lid, two clasps and two rows of prisms, per the photograph.

Calibration Position

Not stated on the datasheet.

Power and Base Marking

Not described.

Case Dimensions and Weight

Not published.

Power Source

None. The set has no electrical parts.

The LS-16 covers ½ to 50 Δ with sixteen acrylic prisms and a red filter in an aluminium case, trading the odd values below 20 Δ for a short, portable list. At large angles its 5 Δ steps sit within the normal variation of the prism cover test. At small angles the gaps mean bracketing, which matters for fine prism trials. Medigear.uk lists the LS-16 for business buyers worldwide and can arrange delivery, familiarisation and service cover. Request the calibration position, power and base marking, case dimensions and the declaration of conformity from the seller at quotation, before the set enters routine clinical use.

FAQ

Frequently Asked Questions

Everything buyers need to know about sourcing medical equipment through MediGear.

Sixteen acrylic prisms and one red filter lens, 17 pieces in total, in an aluminium case. The powers are ½, 1, 2, 4, 6, 8, 10, 12, 15, 20, 25, 30, 35, 40, 45 and 50 Δ. Ask the seller for a written packing list and check the case against it on delivery.

There is no 3, 5, 7, 9, 11, 13 or 14 Δ prism, and nothing at 16 to 19 Δ, 21 to 24 Δ or between the 5 Δ steps above 20. An angle in one of those gaps is bracketed between the neighbouring prisms, or estimated within the bracket.

Less than it might seem at large angles, more at small ones. In a study of 143 children with esotropia, the 95% limits of agreement for a single prism and alternate cover test measurement were about ±7 Δ at distance for angles over 20 Δ, so a 5 Δ bracket falls within normal measurement variation. For small deviations and prism trials, where a change of 2 Δ can matter to the patient, the missing odd values mean some prescriptions are tested only approximately.

Stacking prisms in the same direction before one eye does not simply add their labelled powers, and published work by Thompson and Guyton showed surprisingly large errors when a small prism is added to a large one. Placing one prism before each eye is the usual alternative, recognising that the total is approximate.

In the position they were calibrated for, which the datasheet does not state. Plastic prisms are generally calibrated for the position of minimum deviation, and published guidance treats the frontal plane position, with the back face parallel to the patient's face, as a close practical equivalent. Confirm the calibration position with the seller and note it inside the case.

The datasheet lists 37 × 37 mm, which describes the square face. Thickness increases with power. The clear aperture is not stated separately.

A red filter before one eye makes that eye's image appear red, so a patient with diplopia can say which image belongs to which eye. The datasheet does not describe its intended use.

Loose prisms measure horizontal and vertical strabismus with the prism cover test, including large angles up to 50 Δ in single prisms. The low values from ½ to 10 Δ suit phoria measurement, fusional reserves and simple prism trials, with the gaps noted above.

The datasheet does not say. Confirm that each prism's power is legible and its base clearly identified, since a reversed base reverses the diagnosis.

Acrylic scratches easily, and some solvents can craze it. Clean the prisms only with agents the manufacturer approves, return each to its place in the case after use, and inspect the faces for scratches. Disinfectant compatibility is not published.

The datasheet claims no product standard, and none is cited here. Under UK MDR 2002 loose prisms are typically Class I, or higher, use-dependent, confirmed against the declaration of conformity at order. The declaration is issued by the manufacturer and provided by the seller. Conformity requirements differ by destination market, and the seller confirms what applies where the unit is going.

A clinic running frequent prism trials for small deviations may miss the odd values below 10 Δ. A buyer who needs documented calibration and marking should obtain them in writing before order. Orthoptists, ophthalmologists and optometrists use loose prisms, registered in the UK with the Health and Care Professions Council or the General Optical Council, and other countries set their own rules.