Visionstar 90D

Wide Angle Fundus Viewing

A high dioptre lens gathers a broad angular view, which suits examination where an overview of the posterior pole matters more than scale. The 72 degree field and 0.65 times magnification describe what the lens presents; how that suits any given examination is determined by the clinician rather than the specification. Overview and scale pull against one another here. The lens presents the view; the clinician judges its use. Wide angular gathering is what the power delivers.

Slit Lamp Examination in Routine Practice

Non-contact viewing lenses are standard equipment wherever posterior segment examination happens at a slit lamp, with illumination and magnification supplied by the instrument rather than the lens. The compact element and black ring both suit a clinic where lenses are handled repeatedly through a list. Lenses are picked up and set down repeatedly through a list. Recognition at a glance genuinely saves time in clinic. The instrument supplies what the lens does not.

Examinations Where Contrast Is Critical

Coatings across the optical surfaces reduce reflection at every boundary, and a viewing lens sits directly between a bright slit lamp beam and the examiner's eye. Contrast lost to stray reflection cannot be recovered afterwards, which bears on how readily fine detail is discerned. Contrast lost at a boundary cannot be recovered later. Fine detail is exactly what such examinations seek out. Bright beams make reflection control worthwhile.

Practices Holding Several Powers

Departments typically keep more than one lens power, selected according to the examinations they perform. This is one power within a wider range, and Medigear.uk can advise on what else is available to sit alongside it in a set. Different examinations call for different lens powers. Advice on the wider range is available on request. Sets are assembled according to a service's work.

Wide Field From a Compact Element

Ninety dioptres allows a broad angular view to be gathered through an 18 millimetre aperture, which is a genuine optical achievement rather than a marketing line. The compactness follows directly from the power, and a smaller element is easier to position and handle through a long clinic list. Handling matters across a full clinic day. Compact elements suit repeated handling through a session. Positioning becomes easier with a smaller element.

Both Surfaces Corrected

Double aspheric construction is more demanding than correcting a single surface, and its purpose is entirely peripheral. A wide field that softens toward its edges is narrower in practice than its specification suggests, so correcting both surfaces is what makes the documented figure meaningful. Correcting both is what makes the documented figure meaningful. Both surfaces corrected is the more demanding approach. Peripheral performance is the entire purpose here.

Reflection Controlled Where It Counts

Every air to glass boundary costs a little contrast, and a viewing lens faces a bright illumination source directly. Applying coatings across the surfaces addresses that at source, which matters more here than in optics working under ordinary lighting conditions. Ordinary optics never face illumination of that intensity. Coatings address the problem at its source directly. Contrast preserved is detail the examiner can use.

Ninety Dioptres of Optical Power

High dioptric power gathers a wide angular view into a compact element, which is what allows the small aperture to present a broad field. Aperture and power move together in lenses of this kind.

Seventy Two Degree Viewing Field

The documented field spans 72 degrees, presented through the slit lamp during non-contact examination of the fundus. Illumination and magnification come from the instrument itself.

Image Magnification of 0.65 Times

Magnification below unity is inherent at this power: a wide area is gathered and presented at correspondingly reduced scale. Field and scale move against one another as power rises.

Eighteen Millimetre Clear Aperture

The usable optical area measures 18 millimetres, the most compact of the powers documented in this range. A smaller element is easier to position during a long list.

Ten Millimetre Working Distance

The lens is held 10 millimetres from the eye during examination, without any contact being made with the cornea. Nothing touches the cornea throughout the examination.

Precision Double Aspheric Correction

Both curved surfaces carry aspheric correction rather than one, which is what keeps the outer field usable rather than degrading. A field softening at its edges is narrower than it appears.

Coated High Transmittance Glass

Optical coatings across the surfaces reduce reflection at each air to glass boundary, preserving contrast against a bright beam. Bright illumination makes reflection control worth having.

Black Identification Ring

The mounting ring identifies this power among other lenses held together, without an engraving needing to be read first. Several powers are commonly kept together in a practice.

The 90D is a high dioptre non-contact viewing lens for fundus examination at the slit lamp. Ninety dioptres of power gathers a 72 degree field through an 18 millimetre clear aperture, with image magnification documented at 0.65 times and a working distance of 10 millimetres.

The lens is held before the eye rather than resting upon it. Magnification below unity comes with the power rather than being a shortcoming: a wide area is gathered and presented at reduced scale, and whether that trade suits an examination is the clinician's judgement. Precision double aspheric construction corrects both curved surfaces, which is what keeps the outer field usable rather than softening toward its margins.

Power, aperture and correction all serve the same end here. High transmittance glass carries optical coatings across its surfaces, reducing reflection at each boundary and preserving contrast against the bright beam a slit lamp produces. A black mounting ring identifies the power among other lenses kept alongside it.

Medigear.uk supplies this lens as a verified medical equipment supplier and will confirm the coating specification, storage case, cleaning 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.