Lenses in ophthalmology

LENSES IN OPHTHALMOLOGY
Dr. Reshma Peter

Indirect fundus biomicroscopy
 Examination of the retina by Slit lamp and Volk double aspheric lenses is called indirect
fundus Biomicroscopy
LENS
NON –
CONTACT
CONTACT
CONVEX
LENS
CONCAVE
LENS
+60D
+78D
+90D
HRUBY
LENS
GOLDMANN 3
MIRROR LENS
MODIFIED
KOEPPE’S
LENS
INDIRECT
LENS
+30D
+40D
+14/+
15D

ADVANTAGES
1. Larger field of retina visible
2. Lesser distortion of image of retina
3. Easier to examine , if patient ‘s eye movements are present and with high
spherical or astigmatic refractive errors
4. Easy visualization of retina anterior to equator , where most retinal holes and
degenerations exist
5. It gives a 3D stereoscopic view of the retina wth considerable depth of focus
6. Useful in Hazy media because of its bright light and optical property
DISADVANTAGES
1. Magnification in indirect ophthalmoscopy is 5 times
2. Impossible with very small pupils
3. Patient usually more uncomfortable with intense light and scleral indentation
4. Reflex sneezing on exposure to bright light
5. Requires extensive practice in technique

 Volk's 60D,78D and 90D fundus lenses with slit lamp indirect
ophthalmoscopy as a standard diagnostic procedure for comprehensive
fundus evaluation.
 Double aspheric lenses
 Optics of indirect fundus biomicroscopy is similar to that of indirect
ophthalmoscopy.
 Image formed is real, inverted, laterally reversed.

Technique
 The patient’s pupil may be dilated and background lights dimmed
as for direct ophthalmoscopy.
 Patient is positioned comfortably at the slit lamp.
 The slit lamp viewing piece and the light column are kept at
an angle of 90 degrees.
 Set illumination angle coaxial with the slit lamp-viewing system
 The illumination is kept low, the slit beam at a width of 2-3 mm
and length of 5-10mm

 Magnification preferably set at 10× initially or 16 x
 The beam is focused onto the patient’s pupil and the +78 or +90 D
condensing lens aligned at around 5-10 mm from the patient’s cornea.
 The slit lamp is then pulled backwards gradually towards the examiner
until the fundal glow is visualised
 Reflections can be reduced by slightly tilting the lens
 As with indirect ophthalmoscopy, the image from a non-contact Volk Lens slit
lamp biomicroscopic examination is inverted and laterally reversed.
 To view peripheral retina, ask patient to look into appropriate positions of
gaze as with standard indirect ophthalmoscopy

 Magnification= power of eye x magnification of slit lamp
power of lens
Eg . Magnification of + 90 D = 60/90 x 10 = 7.6
 Thus magnification is inversely proportional while,
Field of view is directly proportional to the power of the lens.
Stereopsis = magnification / 4 .
Field of view = (D.P. of the lens x 2 )

Principle of Indirect Ophthalmoscopy
 To make the eye highly Myopic by placing a
 strong Convex lens in front of it.

+90 D lens
 The original Volk 90D lens started the slit
lamp examination.
 relatively wide field of view with a good
resolution
 Real inverted image
 General diagnosis and small pupil
examinations.
 It features a small 26mm diameter ring is
ideal for dynamic fundoscopy.
 The Volk 90D has very good small pupil
capabilities, making it ideal for a quick look
at the posterior pole.
 Working distance from the cornea is 6.5mm.

60D
 High Magnification Views of the Posterior Pole.
 High magnification lens for detailed optic disc and macula
imaging.
 Ideal diameter for use in the orbital area.
 ( Its 31mm diameter allows a wide field of view and facilitates
 easy handling within the orbital area.)
 • Working distance from the cornea is 11mm.

78D
The Double Aspheric 78D is an excellent general diagnosis .
 Ideal balance of magnification and field of view.
 Working distance from the cornea is 7mm.

Advantages :
1.Stereoscopic ,3 dimensional view of the retina-Binocular viewing
through the slit lamp.
2.Better image achieved when viewing through media opacities -
Cataract.
3.Allows for manipulation of image- Slit lamp magnification& filters.
4.Image size less affected by patient refractive error.

Hruby lens
 Plano-concave lens with diopteric power of -58.6D, which neutralises the
optical power of the eye (+ 60 D)
 To be placed 10-12 mm in front of patient’s cornea.
 Image formed : virtual, erect image 18mm in front of patient’s retina

Disadvantages
 Low magnification 5-8 degrees (just about 1 disc diameter)
 Small field , cannot visualise beyond the equator
 Precise patient fixation required
 Hence it is not ideal for screening posterior fundus

INDIRECT OPHTHALMOSCOPE
LENSES
BIO condensing lenses (Hand held lenses )
 biconvex, aspheric designs with one surface more curved than
theother.
 Less curved surface toward patient’s eye (silver).
 The hand-held lens acts both as:-
1. A condensing lens for the illuminating system.
2. A lens for forming an inverted image of the retina in space.

 The technique is called Indirect because the fundus isseen
through a condensing lens.
 The image is formed close to the principle focus of the lens,
between the lens and the observer.
 The condensing lens is a powerful convex lens (the usual power
used is +14, + 20,and + 33 D )
 The power of the condensing lens determines:-
 Retinal Magnification
 Field of view
 Stereopsis.

+30 D lens
 The high dioptric power lens (30D) has the highest magnification :-
 Least magnification of the retina, 60/30 = 2.
 Stereopsis is half that of the normal, 2/4= 1/2
 Field of view is generally the largest = (60 degrees, 30 x 2 ).
 used to obtain a panoramic view when detail and stereopsis are
not as important , and used with small pupil.

+20 D lens
 The middle dioptric power lens of (20D).
 The retinal magnification = 60/20 = X3
 The stereopsis is 3/4 that of the normal.
 The field of view is 40 degrees (20x2 ).
 20D lens most widely used, since it provides an adequate field of
view, stereopsis and magnification.

+15 D lens
 The low dioptric power lens of 14 or 15D.
 The retinal magnification = 60/15 = X4.
 The stereopsis is full ( 4/4 ).
 The field of view is 30 degrees (15x2 ).
 most useful for detailed view of the macula or optic disc or for
determining elevation of the retina in shallow retinal
detachment.

Contact lens biomicroscopy of fundus
Combines stereopsis, high illumination, and high
magnification with advantages of slit beam
A. Modified Koeppe’s lens
B. Goldmann’ s three mirror contact lens
C. Wide field (panfundoscopic) indirect contact lenses

Modified Koeppe’s lens
 posterior fundus contact lens
 Used to examine the posterior segment
 Virtual and erect image

Goldmann’ s three mirror contact lens
 Central contact lens with 3 mirrors placed in the cone,
each with different angles of inclination
1. central contact lens for posterior pole and vitreous
2. Mirror inclined at 73 ° - area around posterior pole
3. Mirror inclined at 67 ° - equatorial fundus
4. Mirror inclined at 59 ° - anterior peripheral fundus including ora serrata
and pars plana
 Virtual , erect image

TECHNIQUE
1. Dilate pupils
2. Instil topical anaesthetic drops
3. Insert coupling fluid into cup of contact lens but do not overfill
4. Ask patient to look up , insert inferior rim of the lens into lower fornix and
press it quickly against the cornea
5. Always tilt illumination column except when viewing 12 o’ clock position in
the fundus (ie, with the mirror at 6 o’clock)
6. When viewing different positions of peripheral retina, rotate axis of beam so
that it is always at right angles to the mirror

6. To visualize entire fundus, rotate lens for 360 degrees using the 59, 67
and 73 degrees tilted mirrors to give views of the peripheral retina, the
equatorial fundus and the area around the posterior pole, respectively
7.To obtain a more peripheral view of the retina, tilt the lens to the
opposite side and ask the patient to move the eyes to the same side.
Eg-to obtain a more peripheral view of 12 o’clock position (with mirror at
6 o’clock), tilt the lens down and ask the patient to look up
8. Examine the vitreous cavity with central lens, using a horizontal and a
vertical slit – beam and then examine posterior pole

Wide field (panfundoscopic) indirect contact lenses
 Field view upto 130 degrees
 For fundus examination and laser photocoagulation
 Inverted image

PRINCIPLES AND OPTICS
• Critical angle for the cornea-air interface is approximately 46 degrees.
•Total internal reflection prevents direct visualization of angle in
nearly all eyes.
•The incident angle of light- reflected from angle is greater
than the critical angle at the cornea–air interface.

L i < L r
light rays are refracted at the contact lens-air
interface
light rays are reflected by a mirror
light rays leave the lens at nearly right
angles at the contact lens-air interface
Total internal reflection is overcome by eliminate the cornea-air interface by
Goniolenses in DIRECT method contact lenses –-to examine the anatomy of the angle
Gonioprisms/mirror and viscous coupling solution or tears in INDIRECT method
As the index of refraction of a contact lens approaches that of the cornea, there is minimal refraction at the
interface of these two media, which eliminates the optical effect of the front corneal surface.
Thus light rays from the anterior chamber angle enter the contact lens and are then made to pass through
the new contact lens-air interface

METHODS
 Three primary methods:
 Indirect gonioscopy: Using mirrors,the angle is examined with reflected light
 Indentation (dynamic) gonioscopy
 Direct gonioscopy: look directly at the angle with lenses.

GONIOPRISMS(Indirect)
GONIOLENSES(Direct)
Requiring coupling agents Not requiring coupling agents
1.Goldmann single mirror
gonioprism
2.Goldmann 2 mirror gonioprism
3.Goldmann 3 mirror gonioprism
4.Allen Thorpe gonioprism
1.Zeiss 4- mirror Gonioprism
2.Posner Gonioprism
3.Sussman lens
4.Tokel Gonioprism
5.Ritch Trabeculoplasty laser lens
1.Koeppe Goniolens
2.Huskins Barkans lens
3.Thorpe Goniolens
4.Swan Jacob ‘s lens
5.Richardson Shaffer’s Goniolens
6.Worth goniolens
7.Sieback goniolens

GONIOPRISMS
Requiring coupling agents
1.Goldmann single mirror gonioprism
Prototype diagnostic gonioprism
 Mirror inclined at 62 degrees from plano front surface
 Needs to be rotated 3 times to examine the whole angle
 Mirror Height -12 mm
 Central well diameter -12 mm
 Posterior Radius of curvature -7.38 mm
2.Goldmann two mirror gonioprism
 Both mirrors inclined at 62 degrees
 Needs to be rotated once to examine whole angle

3.Goldmann three mirror gonioprism
A. Gonioscopy mirror: Inclination of 59 degree
 Smallest
 Dome shaped upper border
 Broad area of contact with cornea (12 mm)may artificially close the angle under pressure
B. Equatorial mirror: Inclined at 67 degrees
 Largest
 Oblong shaped
 Examine Pars plana of ciliary body
Posterior pole to the equator
C. Peripheral mirror: Inclined at 73 degrees
 Intermediate size
 Square shaped
 Examine from equator to ora serrata

4.Allen Thorpe gonioprism
 4 prisms instead of mirrors
 Allows examination of whole angle without rotating the prisms
 Suspended by a frame

Advantages of Goldmann gonioprisms
 Easy to use
 Excellent view
 Peripheral retina can be seen
 Stabilizes the globe Can be used in Argon Laser trabeculoplasty

Disadvantages of Goldmann gonioprisms
 Only 1 mirror for gonio-has to be rotated by 360 degrees
 Cannot be used for indentation
 In case of 3 mirror lens, broad area of contact with cornea may cause
artefactual closure of angle
Curvature of lens > cornea
Coupling material required
Blurs vision and fundus
Field charting ,direct and indirect
ophthalmoscopy
cant be done immediately after use

GONIOPRISMS
Not requiring coupling agents
1.Zeiss 4- mirror Gonioprism
 4 identical mirrors angled at 64 degrees
 On an UNGER HOLDER
 Small area of contact with the cornea (9mm)
Indentation gonioscopy can be performed

Zeiss 4- mirror Gonioprism
ADVANTAGES DISADVANTAGES
• Easy to perform
• All 4 quadrants visible at
same time
• Rotation of 11 degrees
covers area between the
mirrors
• Indentation gonio
• Coupling material not
required,
thus fundus viewing and
photography possible
• Difficult to master
• Does not stabilise the
globe
• May open the angle
artefactually If
pressure is applied

2.Posner Gonioprism
 Similar to Zeiss
 Made of plastic instead of glass
 Has a fixed handle

3.Sussman lens
Similar to Zeiss
but has no handle
4.Tokel Gonioprism
• Single mirror lens
• Broader viewing area
than Goldmann single mirror lens
• Convex anterior face that provides slight
magnification
• For delivery of Laser to angle

5.Ritch Trabeculoplasty laser lens
 2 mirrors tilted at 59degrees to see inferior angle
 2 mirrors at 64 degrees to view the superior angle
 A convex button in front of a 59 degree mirror and a 64 degree mirror for extra
magnification and laser treatment

GONIOLENSES
Koeppe lens
 Prototype diagnostic lens
 Available in several sizes
 Most commonly used lens
for diagnostic direct gonio.
Huskins Barkan lens
 Prototype surgical goniolens
 Used for Goniotomy
Thorpe Goniolens
Surgical and diagnostic lens for operating rooms

Swan jacob’s lens
• Surgical goniolens
• used in children
Richardson Shaffer’s lens
Small lens for use in infants
Worth goniolens
It anchors to the cornea by partial vaccum
Sieback goniolens
Tiny goniolens which floats on the cornea

2 types of laser lenses are available to assist in slitlamp delivery of
photocoagulation:
 Plano-concave lenses
 an erect image
 high resolution of small retinal area.
 mirrors angulated at 59 , 69 and 73 degrees
 High plus power lenses(indirect lens)
• an inverted image
• mild loss of fine resolution
• a wide field of view very suitable for PRP

Common characteristics of laser lenses
 Concave posterior surface conforming to the corneal curvature and a
flat or convex anterior surface
 Planar mirrors allowing observation of the anterior chamber angle or
peripheral retina.
 A prism to allow visualization of the mid-periphery of the retina.
 A flange to stabilize the lens and prevent blinking
 Knurled edge to facilitate lens manipulation.
 Laser lenses generally consist of a conical PMMA or aluminium shell
 Glass anterior surface, lenticular elements and mirrors.

Antireflection coatings
 Usually applied to each optical surface in a laser lens that reduces
reflected white light (from the slit lamp source) that could decrease contrast or the
slit lamp image, and laser light (from the treatment beam) that could pose a
potential hazard to an observer standing behind the laser operator.
 The hazard distance is 7 meters for an uncoated lens and 1.6 meters for a coated
lens.
 Most laser lenses use broad-spectrum, multilayer, antireflection coatings that
reduce reflected light between 400 nm and 700 nm from approx 4 %
to < 1%

Mirror lenses
 high magnification and high resolution
 only a small part of the fundus or chamber angle can be viewed at any one time.
 Therefore, the mirrors at various degrees of inclinations are necessary.
e.g. Goldmann 3 mirror lenses.
The image formed in the Goldmann 3 mirror lens is the mirror image of the area focused.
Lenses without Mirrors
 field of view may be increased to a variable extent by use of biconcave contact
lenses based on the simple Goldman lens (without mirrors).
 Another different way of increasing the field of view involves using contact lenses
based on the EL Bayadi lens.Eg- Rodenstock Panfundoscope and Mainster lens
 All wide-angle systems of this category are derived from the principle of indirect
ophthalmoscopy
 large and inverted field of view.
 both the panfundoscope and the Mainster lenses produce inverted real images.

Goldmann Lens
 Single mirror inclined at 62 degrees or 3 mirror with gonio mirror
at 59 degrees
 Rotated 360 degrees to view angles structures
 Flat ant surface
 Erect virtual image near post surface of lens
 Limited field of view without rotation

Yannuzzi fundus lens(Krieger lens )
 modification of an earlier model developed by
Krieger in 1966
 designed to facilitate macular photocoagulation
 concave corneal surface which is steeper and of
greater diameter,
 has a better optics than a simple Goldman
fundus lens
 allows posterior lens pressure to be transmitted
to the sclera without distorting the cornea.
 erect, virtual located in anterior vitreous
humor.

Volk Area centralis lens
 indirect contact lens
 a good field of view 70/84 degrees
 excellent magnification 1.06x.
 Laser spot magnification is 0.94x.

Volk PDT lens
 The field of view is 115/137 degrees
 Image magnification is 0.67x.
 Laser spot magnification is 1.5 x
 allows treatment of CNVM upto maximum spot size of
6400um providing excellent visualization
 comes standard with SupraCoat which covers the 689nm
laser wavelength indicated in this type of procedure.

Volk Transequator lens
 designed for focal laser therapy and mid-to-far peripheral
fundus diagnosis.
 unique optical design presents a realistic contour of the retinal
concavity, offering an impressive wide-field of view of the entire
posterior pole extending to the equator.
 superior optics allow dynamic movement on the globe, therefore
increasing its functional field of view.
 The field of view is 110/132 degrees.

Mainster
 Introduced in 1986
 more field of view (58% greater than Goldman) and a
greater magnification.
 Although the field of view is 14% less than the
Panfundoscope,
but the lateral and axial magnification are better which
makes it useful for detecting retinal thickening.
 It has a biconvex, aspherical anterior lens element and a
concave lens element to fit the corneal curvature.
 inverted, real image located in front of its biconvex
aspheric anterior lens element

Common Features of Mainster and Panfundoscopic lens
 Large areas of the fundus may be treated in PRP without lens
rotation.
 Visualization of the optic disc and macula during peripheral
treatment prevents disorientation.
 The experienced laser surgeon can achieve a more peripheral
view by tilting the lens off-axis.
 The field of view is increased in myopes and decrease in
hyperopes and will lead to differences in how far peripherally
laser photocoagulation can be applied.
 Working distance on these lenses are greater.
 Anterior segment irradiance becomes excessive with large spot
sizes (1000μm) but should be acceptable at a spot size of 500μm.

Mainster Standard lens
 for focal and grid laser treatment from the posterior pole to the
midperiphery.
 field of view is 90/121 degrees.
 Image magnification is 0.96 x.
 High resolution, high magnification of image allows appreciation
of subtle intraretinal details and retinal thickening.
 So, it is excellent for diagnosis and treatment of macular
oedema, BRVO , CNVM in ARMD and presumed ocular
histoplasmosis.

PRP Lenses
Mainster wide field lens
 This allows a very wide range of slit lamp magnification to be
used.
 It has excellent ophthalmic resolution and image binocularity is
maintained across the entire field of view.
 used for PRP in PDR
 The field of view is 118/127 degrees.
 Laser spot magnification is 1.50 x.

Mainster Ultrafield PRP lens:
 widest field of view available for PRP
 It has a unique optical design to provide a clear, bright image
across the entire field.
 light- weight, has a secure fit flange for easy manipulation
besides having a high efficiency laser light anti-reflective coating.
 field of view is 165/180 degrees.
 Image magnification is 0.51 x.

Rodenstock Panfundoscopic lens
 Introduced in 1969 by Schlegel
 used for PRP from the posterior pole to beyond the equator
without the use of mirrors.
 gives a panoramic view
 inverted, real image located in its spherical biconvex anterior lens
element.
 Thus, the biomicroscope must be located further from the
patient's eye than using a Goldman lens

 This low biomicroscopic magnification produces adequate
magnification with a large field and acceptable depth of
focus.
 working field is 84% greater than a Goldman
 lateral magnification is 24% lesser than a Goldman.
 The spot size is 40% larger than the photocoagulator setting
or twice large than the conventional contact lens.
Disadvantage
• it produces peripheral distortion.
• It can produce marked laser beam astigmatism while
treating the peripheral retina.
• Reflexes compromise retinal image thereby causing oblong
burns when treating through the periphery of the lens.

Volk Quadraspheric lens
 The original 13 degree Quadraspheric introduced in 1989
 preferred wide field fundus laser lens for diagnosis and
treatment of the retina.
 The 4 aspheric surfaces also employ high efficiency antireflection
coatings thereby improving lens performance by reducing
astigmatism across the entire field of view.
 It also enhances visualization through a small pupil.
 inverted and reversed image.
 Its sleek 28.6mm diameter housing provides a definite advantage
over competitive wide field lenses for peripheral retinal viewing,
reflection displacement and ease of use.
 The laser spot magnification is 1.97x
 The image magnification is 0.51x.

Volk Super Quad 160 lens
 offers the widest field of view.
 ideal 0.5x image magnification
 simultaneous visualization of the posterior pole to the peripheral
retina providing a greater margin of safety even during extreme
wide angle panretinal photocoagulation.
 field of view is 160/ 165 degrees
 Image magnification is 1.97x
 laser spot magnification is 2.0x.
 the ideal lens for visualization and treatment of PDR, ischaemic
RVO and peripheral retinal holes and tears.
 Laser beam transmission and fundus image quality are sharp and
undistorted to the full extent of the viewing field.

 Volk has introduced two new high resolution (HR) lenses for laser
photocoagulation
– The HR Wide Field for Pan Retinal Photocoagulation (PRP)
– The HR Centralis for focal and grid laser therapy
 Both lenses feature double aspheric designs and high grade, low
dispersion glass which gives superior imaging quality.
 Both lenses may also be used as diagnostic lenses as well.
 The lenses improve upon and replace the previous generation
Superquad 160 and Area Centralis lenses.
 Primary conditions diagnosed and treated are diabetic retinopathy
and maculopathy.
 Lenses can also be used to diagnose and treat other conditions such as
retinal tears, breaks and holes.

HR Centralis Lens
 Lens for detailed posterior pole examination and laser focal/grid
treatment
 Lens is an upgrade or replacement for:
– Volk Optical Area Centralis
– Ocular Mainster 1X Retina
– Ocular Mainster Focal/Grid
 better image quality and stereopsis at the extreme of the lens view
 Specifications: FOV 74º, magnification 1.08x, laser spot 0.92x

 Enhanced double aspheric design eliminates distortion and
improves stereopsis to the periphery of the view
 Superior, high grade, low dispersion glass delivers unsurpassed
resolution
 Improved capability with pupils as small as 4mm
 Reduced sized housing helps manipulation within the orbit

HR Wide Field Lens
 Lens for extreme wide field examination and laser PRP treatment
 Lens is an upgrade or replacement for:
– Rodenstock pan fundus lens
– Volk Optical Superquad 160
– Ocular Instruments Mainster PRP 165
 better image quality at the extreme periphery of the lens view
 Specifications: FOV 160º, magnification 0.5x,laser spot 2.0x

 Widest field of view and treatment area to the ora serrata
 Superior, high grade, low dispersion glass design eliminates
distortion at the extreme periphery
 Much smaller and easier to manipulate within patient’s orbit
 Short length of lens helps manipulate in front of laser

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

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-WF
 Hands 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 surgery
 Too loose- decentration of lens
 Bleeding can obscure view of surgeon.

 Plano concave lens – core vitrectomy
Landers 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 portion
 Tolentino 20 degree prism – periphery
 Tolentino 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

OPTICS OF CONVENTIONAL
VITREOUS SURGERY
 A Plano-concave contact lens made of PMMA
 Refractive index of 1.488 and a concave posterior surface radius
of curvature of 7.7 mm is
 Refractive power of the anterior surface 48.8 D to -14.5 D and
the fundus is easily visualized

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 D
 Field of View is 130 deg.
 Microscope eye piece should be moved closer toPatients eyes.

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
 When The OSVS-U132-2 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

Resight 700 from Carl Zeiss
 Can 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)

Contact Wide field lenses
 Inverted image , Need of SDI
 Field of View = 120-130 degree
 Held by handle or Standard lens ring

Reinverting Operating Lens
System
 Single element reinverter prism design to correct the inverted
image.
 Super Macula lens -60 deg
 Mini Quad lenses -127 deg
 Mini Quad XL lenses – 134 deg
 Dyna – 156 deg

High index corneal contact lenses
 Form essential part of image capturing unit
 Allow capturing of oblique rays emerging from peripheral retina
 The changeable lenses (nose pieces )available to be attached to
the image – capturing unit of Retcam II are as follows
LENS FIELD OF VIEW
ROP lens premature infants 130 degrees
Standard children lens pediatric to young adult 120 degrees
High magnification lenses Fine details 30 degrees
80 degree lens Higher contrast pediatric and
adult imaging
80 degrees
Portrait lens For external imaging

Lenses in ophthalmology

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