wide angle viewing field systems in vr surgery

Wide Angle Viewing Field Systems in VR Surgery

Dr Rajvin Samuel Ponraj Fellowship Sankara Eye Hospital Pammal


Vitreous Surgery requires the help of Special devices to clearly visualize the Retina and Vitreous.

Contact Type :VPFS ( Vitreous Panfundoscope)CWF (Contact wide field System)AVIS (Advanced Visual Instrument system)ROLS (Reinverting Operating lens system) - Clarivit - HRX (Volk Optical)Non Contact Type : - BIOM (Binocular IDO) – (Oculus) - MERLIN –(Volk Optical ) - EIBOS (Erect Indirect Binocular IDO)- - OFFISS (TOPCON) - RESIGHT (Carl Zeiss) - Peyman –

Wessels- Landers Dr Rajvin Samuel Ponraj Fellowship

Sankara Eye Hospital Pammal


Hand Held Irrigating Contact lenses Neutralize High Convergence of Corneal

Curvature to focus on Retina , Vitreous. 3 types of Lenses: - Plano concave lenses with a view of 20

degrees- Biconcave lenses with view of 30 degrees- Prism lenses with meridonial view of 60

degrees


Hands Free Contact Lens (Landers System) OLIV-WFHands free contact lenses were introduced

by Landers and co workers which were stabilized onto the cornea with the help of a sewn-on limbal ring (stainless steel )

Too tight – corneal folds,break suture midway of surgeryToo loose- decentration of lensBleeding can obscure view of surgeon.


Plano concave lens – core vitrectomyLanders biconcave lens – visualization in air

filled eye (90 D Lens – 25 deg angle field)Machemers magnifying lens – surface

details on posterior pole (28-30 deg angle field)

Peyman wide field lens –equatorial portionTolentino 20 degree prism – peripheryTolentino 30 degree prism – extreme

periphery


Disadvantages: - Limited field of view - Peripheral Retina seen only with

Indentation - Lens alignment problems -Air Bubble/ Blood film coming beneath Lens

System -Poor visualization in Small pupils and Fluid –

gas exchange


Conventional Viewing SystemAdvantages: Lower Cost Non – Inverted Image Less learning curve for Surgeon Excellent resolution

Disadvantages : View compromised with Corneal opacity,

Lenticular haze and Small pupils.


OPTICS OF CONVENTIONAL VITREOUS SURGERYA Plano-concave contact lens made of polymethylmethacrylate Refractive index of 1.488 and a concave

posterior surface radius of curvature of 7.7 mm is used

Refractive power of the anterior surface 48.8 D to -14.5 D and the fundus is easily

visualized


Principle of Indirect OphthalmoscopyTo make the eye highly Myopic by placing a

strong Convex lens in front of it.


Wide Angle Viewing SystemsContact and Non Contact - Both provide Panaromic View up to Ora

serrata and enhances the safety and efficiency of Surgery

- Problems of High Cost - Inverted image is unsuitable - Bulky and long learning Curve - Distortion of Anatomy interferes with

Quality of Fundus image.


Wide Angle Viewing SystemsContact Non ContactAdvantagesImage resolution and stereopsis better

No intraoperative Corneal trauma

Eliminates corneal aberrations & limits the number of reflecting surfaces

Good view during Fluid air exchange

Wider field of view- Less need of Ocular rotation

Good view - small pupils and irregular corneas

DisadvantagesPoor view in case of corneal or lens opacity/ haze

Poorer image resolution and depth perception

Chance of corneal deformation Learning curve - moreChange in IOP


OPTICS OF CONVENTIONAL CONTACT LENSES The first component (inferior lens) –acrylic

contact lens concave posterior surface. Power of 4 D.

The second component (superior lens) -biconvex aspherical image-forming, high refractive index glass lens 0.5 mm anterior of the contact lens element and an effective

power of 150 D in air.

Real, inverted, aerial retinal image anterior to the image forming lens system.


Optics in Air Filled Eye


Posterior surface of the lens becomes strongly refractive

(64 D) Total refractive power of the eye increases

from 59 to 102 DField of View is 130 deg.Microscope eye piece should be moved

closer to Patients eyes.


Oculus BIOM & SDI-Stereoscopic Diagonal Inverter.

Requires SDI to invert the indirect image from BIOM to a conventional upright image (Internalised Prismatic system Foot pedalled & Automatic ) (Near Zero Light Escape) Easily adaptable to microscopes, sterilised easily Field of view = 70, 90, 110

degrees


Peyman-Wessels-Landers 132 D Upright Vitrectomy Lens

Wide field Upright images without invertor (Internalised prisms).

Operating Table mounted system ,Can be attached to any microscope


The OSVS-U132-2 is a non-contact vitrectomy lens system designed with a flexible arm for positioning wide-angle lenses, which easily swings in and out of the surgical field. The OSVS (clamps) attaches to the wrist rest or surgical bed, freeing the surgeon and assistant to perform tasks other than holding the lens. When used with the Ocular Peyman-Wessels-Landers 132 Diopter Upright Vitrectomy Lens (OUV-132-2), the system allows the surgeon to work in the vitreous with an upright, non-reversed image under panoramic viewing conditions


OFFISS- Topcon OMS-800Optical fibre free Intravitreal Surgery systemIncorporated illumination , No need of Light

probeCan perform Bimanual surgical techniques.Working distance is more ,hence less chance

of lens touching cornea.Higher cost as the whole system including the

microscope must be bought.


EIBOS Erected Image Binocular microscopeIncorporates Inverter and indirect systems in one piece. Inverter cannot be used independently.Incorporates Spring balanced safety – elevation of the Unit if Lens comes in contact with the eye.Field of View = 100,125 degrees.90,132 D Lenses


Resight 700 from Carl ZeissCan hold two lenses simultaneosuly - 127 deg lens for Wide Angle field - 60 deg lens for High resolution Macular

lens


Contact Types VPFS ( Vitreous Panfundoscope)CWF (Contact wide field System)AVIS (Advanced Visual Instrument system)ROLS (Reinverting Operating lens system)


Vitreous PanfundoscopeModified Rodenstock panfundoscopeField of view = 130 – 150 degNeed of SDI. Inverted image.Easy introduction of instruments without

disturbing lens.Hand held stabilized and heavy compared

to other lenses.


Contact Wide field lensesInverted image , Need of SDIField of View = 120-130 degreeHeld by handle or Standard lens ringLighter and smaller than VPFL


Advanced Visual Instrument SystemAVI stereo inverter2 miniature contact lenses

68 and 130 degree field of viewsHand held by assistant or self retaining

ring

Smaller,lighter, allows easy manipulation of lens

Allows visualization of fundus through small pupil or air filled eye.


Reinverting Operating Lens System

Single element reinverter prism design to correct the inverted image.

Super Macula lens -60 degMini Quad lenses -127 degMini Quad XL lenses – 134 degDyna – 156 deg

wide angle viewing field systems in vr surgery

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