Sale on Manual & Electric Hospital Beds - Starting from 25 September!

Home
Shop
ENT, Ophthalmic & Sensory
Visionstar LS-22

✓ Certified Professional Seller

Visionstar ENT, Ophthalmic & Sensory

Visionstar LS-22

Product Code: EOAS-ECA-3668

Up to 50 Δ in a single prism, so large angles need no stacking.

Neutralise most angles with one prism in one position: twenty-two acrylic prisms from ½ to 50 Δ, each 37 × 37 mm, plus a red filter lens, held in a graded foam tray inside an aluminium case with clasps.

Sections

Examination Lenses & Racks

Categories

ENT, Ophthalmic & Sensory

Condition

New

Origin

China

Seller Type

Certified Professional Seller

CE & ISO Certified

Global Shipping

Supplier: Medigear

In the LS-22, Visionstar supplies loose acrylic prisms of ½, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45 and 50 Δ, each listed at 37 × 37 mm. With one red filter lens the datasheet totals 23 pieces, and the count agrees with the list. The set is packed in an aluminium case, shown in the photograph with two clasps and a foam tray graded by prism size. The calibration position, weight, case dimensions and power marking are not published.

Its value lies in the single-prism mechanism. Every whole value from 1 to 10 Δ is present, then 2 Δ steps to 20 Δ and 5 Δ steps to 50 Δ, so most angles are neutralised by one prism in one position. That matters because stacking prisms in the same direction before one eye does not add up simply. Published work by Thompson and Guyton showed surprisingly large errors when a small prism is added to a large one. When one prism still falls short, the practitioner can split the measurement, placing a prism before each eye.

Loose plastic prisms are generally calibrated for the position of minimum deviation. Published guidance treats the frontal plane position, with the back face parallel to the patient's face, as a close practical equivalent. This datasheet states neither, so confirm the position before measurements guide surgery.

Medigear.uk lists the LS-22 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 are the natural setting for loose prisms. Large infantile esotropias and sensory exotropias often need powers well above 20 Δ, and a single prism of up to 50 Δ lets the orthoptist neutralise most of them without combining prisms before one eye.

Strabismus surgery planning depends on accurate measurement of the largest angle at distance and near. Holding one prism in its calibrated position removes the error that stacking introduces, and confirming that position before surgical measurements is part of accurate dosing. For angles beyond 50 Δ, prism can be divided between the eyes.

Neuro-ophthalmology and stroke services measure acquired diplopia, and the low values from ½ to 10 Δ suit small vertical deviations and prism trials before a correction is prescribed. The red filter helps a patient identify which image belongs to which eye.

Paediatric clinics use loose prisms when a child's gaze needs to stay on a target while the examiner changes powers quickly, and the prisms can be held before either eye as needed.

Optometry practices with a binocular vision interest use the low powers for fusional reserves and prism trials, where single steps from 1 to 10 Δ give fine control.

Research and teaching clinics benefit from a set close to the increments specified in published intermittent exotropia protocols, which supports consistent technique across examiners.

The set is less suited to clinics that prefer sliding through powers on a bar, and to buyers needing 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.

One Prism for Most Angles

Powers reach 50 Δ in single prisms, so most deviations are neutralised without stacking.

Every Whole Value to 10 Δ

Single steps from 1 to 10 Δ, plus ½ Δ, give fine control for small deviations and prism trials.

Large-Angle Coverage

Steps of 5 Δ from 20 to 50 Δ cover the large angles seen in infantile and sensory strabismus.

Works Before Either Eye

Loose prisms can be placed before either eye or split between both, which suits combined and very large deviations.

Red Filter Included

A red filter lens supports diplopia assessment alongside prism measurement.

Square 37 mm Faces

Each prism is listed at 37 × 37 mm, a size that is easy to hold and position.

Graded Foam Tray

The photograph shows a foam tray with a slot for each prism, which keeps the set ordered and protects the faces.

Aluminium Case

A rigid case with two clasps protects the set in storage and transit.

Powers

½, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45 and 50 Δ.

Prism Count

Twenty-two.

Red Filter

One red filter lens.

Total Pieces

Twenty-three, per the datasheet.

Prism Size

37 × 37 mm.

Material

Acrylic.

Case

Aluminium, per the datasheet.

Case Details

Two clasps and a graded foam tray, 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-22 is a set of twenty-two acrylic loose prisms from ½ to 50 Δ with a red filter, in a foam-lined aluminium case. Its strength is that most deviations, including large infantile and sensory angles, can be neutralised with one prism in one position, avoiding the errors of stacking. The calibration position is not stated and must be confirmed before measurements guide surgery. Medigear.uk lists the LS-22 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 first clinical session.

FAQ

Frequently Asked Questions

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

Twenty-two acrylic prisms and one red filter lens, 23 pieces in total, in an aluminium case. The powers are ½, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45 and 50 Δ. The datasheet lists one of each value. Ask the seller for a written packing list to check against on delivery.

The datasheet gives 37 × 37 mm, which describes the square face of each prism. Thickness varies with power, as the graded foam tray in the photograph shows. The clear aperture is not stated separately.

Because stacking prisms is unreliable. Two prisms placed in the same direction before one eye do not give the sum of their labelled powers, and the error grows with larger values. With single prisms up to 50 Δ, most deviations can be neutralised with one prism in one position. For angles beyond 50 Δ, prism can be split between the two eyes, 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 as a close practical equivalent. Glass prisms use a different position altogether. Confirm the calibration position with the seller and record it on the case, so every examiner holds the prisms the same way.

A red filter placed before one eye makes that eye's image appear red, so a patient with diplopia can say which image belongs to which eye. It supports simple diplopia assessment and can be used alongside prism measurement. The datasheet does not describe its intended use.

Loose prisms measure horizontal and vertical strabismus with the prism cover test, particularly large angles such as infantile esotropia and sensory exotropia. The low values from ½ to 10 Δ also suit prism trials for diplopia, measurement of fusional reserves and small vertical deviations. Research protocols for intermittent exotropia have specified loose plastic prism sets with increments very close to this range.

Measurement variation in strabismus is large. In a study of 143 children with esotropia, the 95% limits of agreement for the difference between two prism and alternate cover test measurements were about ±10 Δ at distance for angles over 20 Δ. Using the same prisms and holding method at each visit keeps avoidable variation out of the comparison.

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

Acrylic scratches easily, and some solvents can craze it. Clean prisms only with agents the manufacturer approves, return each to its slot in the foam tray 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.

Orthoptists, ophthalmologists and optometrists use loose prisms to measure strabismus and trial prism corrections. In the UK, orthoptists are registered with the Health and Care Professions Council and optometrists with the General Optical Council. Other countries set their own professional rules.

A clinic that measures only small deviations may find the higher powers unnecessary. A service that prefers to slide through powers with one hand may favour a prism bar. A buyer who needs documented calibration and marking should obtain them in writing before order.