Visionstar 78D

Fundus Examination at the Slit Lamp

A non-contact lens of this kind is held before the patient's eye while the slit lamp provides illumination and magnification. A 78 degree field with 0.93 times magnification describes what the lens presents; whether that combination suits a particular examination is determined by the clinician rather than by the specification. Illumination and magnification come from the slit lamp itself. The lens itself provides neither of those things. Both come from the slit lamp the lens is used with.

Routine Ophthalmic and Optometric Practice

Non-contact viewing lenses are standard equipment wherever posterior segment examination is carried out at a slit lamp. The black ring makes the lens quickly identifiable where several powers are kept together, which matters in a busy clinic where lenses are picked up and put down repeatedly. Lenses are picked up and set down repeatedly through a list. Recognition at a glance saves time across a full list. Standard equipment wherever posterior segment work happens.

Examinations Where Contrast Matters

Multiple coatings reduce reflection at each optical boundary, and a viewing lens sits directly between a bright beam and the examiner. Reducing stray reflection preserves contrast in the image, which bears on how readily fine detail can be discerned during an examination. Contrast bears on how readily fine detail can be discerned. Stray reflection subtracts from the image the examiner sees. Fine detail is exactly what such examinations seek.

Practices Building a Lens Set

Departments and practices typically hold several powers rather than one, chosen according to the examinations they perform. This lens is one power within a wider range, and Medigear.uk can advise on what else is available alongside it. Different examinations call for different lens powers. Practices commonly hold several powers rather than one. Advice on the wider range is available on request.

Aspheric on Both Surfaces

A double aspheric design is a more demanding construction than a single aspheric element, and the reason for it is peripheral performance. A wide field is only useful if the edges of that field remain readable, and correcting both surfaces is how a lens delivers a view that stays usable toward its margins rather than degrading. Edge performance is what a wide field ultimately depends upon. A field that degrades at its margins is narrower in practice. Both surfaces corrected is the more demanding approach.

Coatings Where They Count

Every air-to-glass boundary in an optical path reflects some light, and each reflection subtracts contrast from the image. Applying multiple coatings across the surfaces addresses that directly, which is worth more in a viewing lens than in most optics because the lens works against a bright illumination source. Contrast lost to reflection cannot be recovered afterwards. Coatings matter more here than in most optical applications. Each boundary in the path costs a little contrast.

Identification at a Glance

Ring colour is a small thing that saves time repeatedly. Where a practice keeps several lens powers together, being able to identify one without reading an engraving means the right lens reaches the hand faster during a consultation. The right lens reaches the hand faster during a consultation. Small conveniences accumulate across a working day. Time saved during a consultation is worth having.

Double Aspheric Design

Both optical surfaces carry an aspheric profile rather than one, which is what supports a wide viewing field without peripheral distortion. Correcting both surfaces is a more demanding construction.

78 Degree Field of View

The documented field is 78 degrees, giving a wide view of the fundus through the slit lamp during examination. A wide field is only useful where its margins stay readable.

0.93 Times Image Magnification

Image magnification is documented at 0.93 times, which describes how the viewed image scales rather than recommending any particular use. Field and magnification are read alongside one another.

10 Millimetre Working Distance

Working distance is 10 millimetres, placing the lens close to the eye during non-contact examination. The lens is held before the eye rather than touching it.

26 Millimetre Clear Aperture

The clear aperture measures 26 millimetres, defining the usable optical area of the element itself. It sits alongside three further documented figures.

High Transmittance Glass

The optical element is described as high transmittance glass, which governs how much light reaches the examiner through the lens. Transmittance bears directly on what the examiner sees.

Multiple Optical Coatings

Coatings applied across the surfaces reduce reflection at each air-to-glass boundary, preserving contrast where fine detail is sought. A viewing lens works against a bright illumination source.

Black Ring Identification

The mounting ring is black, identifying this power at a glance among other lenses on a bench or in a drawer. Colour identification is a convention rather than optics.

The 78D is a non-contact fundus viewing lens built on a precision double aspheric design, with both optical surfaces corrected rather than one. That construction is what supports a wide viewing field whose margins remain readable rather than degrading toward the edges.

The documented figures are a 78 degree field of view, image magnification of 0.93 times, a working distance of 10 millimetres and a clear aperture of 26 millimetres. High transmittance glass carries multiple coatings across its surfaces, reducing reflection at each boundary and preserving contrast against the bright illumination a slit lamp provides.

Both the construction and the coatings address the same underlying problem, which is presenting a wide field that stays readable throughout. The element is mounted in a black ring, which identifies this power among other lenses kept alongside it. That is a practical convention rather than an optical feature, and it saves time in a clinic where several powers are held together.

Medigear.uk supplies this lens as a verified medical equipment supplier and will confirm the coating specification, storage case, cleaning and handling guidance, condition and accessory content. How the lens suits any given examination is determined by the clinician using it. Contact the team to discuss specification.