New options for the intolerant RGPwearer: Minisclerals€¦ · Lost RGP lens, lab unable to duplicate fitting or Rx (poor VA) + discomfort. Keratoconus and Corneal grafts –Miniscleral

New options for the intolerant RGP wearer:Minisclerals

Richard VojlayAssociate Professor (Melb Uni) BSc Optom LOSc FVCO

Dip Oc Therapeutics Dip Humanities (Music)

Successful RGP wearer –Keratoconus and Corneal grafts

What is a successful lens?

� Good vision

� Stable

Comfortable

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� Comfortable

� Quiet eye (not red) with tolerable staining

� Can be reliably worn for most of the day.

� The aim is to generate an even bearing surface across the

cornea/graft, adequate but not excessive edge lift or to vault the

graft completely.


� RGP KC fitting

� VA with RGP 6/8-2

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� RGP Corneal

graft fitting


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Keratoconus and Corneal grafts – RGP fitting

� Fitting irregular and asymmetrical surfaces - KC

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� Fitting irregular and asymmetrical surfaces – Corneal grafts

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Keratoconus – RGP fitting

� Fitting options – Small, Medium or Large

� Small

� Nipple cones

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� Nipple cones

� 7.8 mm diameter

� Quadcurve



� Medium

� 9.0 mm diameter

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� 9.0 mm diameter


� Quadcurve



� Medium

� 10.1 mm diameter

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� Bi-sym CLC



� Large


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13.0 mm diameter

� Limbal Lift ACL

(previously K series)

Corneal grafts – RGP fitting


� Small

� 9.0mm diameter

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� 9.0mm diameter

� VA with RGP 6/12-



� Medium


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� VA with RGP 6/6-



� Large


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� VA with RGP 6/6+2

� Limbal Lift ACL

(previously E series)

Quadrant Zoning – inferior tuck

� Fitting options – Very large

� Scleral – custom, trial sets

� 23 mm diameter


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23 mm diameter

� May be fenestrated for tear exchange

� Custom lenses can be very labour

intensive to produce

� Trial sets can reduce fitting times and

assist with reproducibility

� Fitting options – Very large

� Minisclerals

15 - 16.0 mm diameter

Keratoconus and Corneal grafts – Miniscleral RGP lenses

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� 15 - 16.0 mm diameter

� Vault cornea from sclera to

sclera

� Sealed system, no tear exchange

� High Dk material

� V with c/l: 6/6-2

Successful RGP wearer – Keratoconus

� Predicting success – what works?, more reliable with keratoconus

Hopefully Very unlikely

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Unsuccessful RGP wearer – Keratoconus

� Intolerant RGP wearer – options

� soft carrier lens

� SynergEyes

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� SynergEyes

� referral for an opinion by another optometrist

� referral for a corneal graft or regraft.

� All of these lenses are successful - good vision, reliable wearing times,

stable, good comfort, no graft rejections.

Successful RGP wearer – Corneal grafts

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�

Unsuccessful RGP wearer – Corneal grafts

� All of these lenses were unsuccessful - good vision, unreliable wearing

times, stable, variable comfort, graft rejections

� Difficult to predict a successful fitting on a corneal graft

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Patient’s reasons for intolerance –Keratoconus and Corneal grafts

� General discomfort

� Reduced and unreliable wearing times

� Poor quality vision, especially at night

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� Poor quality vision, especially at night

� Intense discomfort from foreign bodies

� Contact lens instability – unusual eye positions

and sport

� Conjunctival hyperaemia

� Minisclerals - characteristics

� No movement

� No lid interaction

Sealed system – no foreign bodies


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� Sealed system – no foreign bodies

underneath the lens

� Tear film reservoir

� High DK material

� Excellent centration

� Large optic zone

� Will not displace

� minimal or no corneal bearing

� Minisclerals – patient experience

� Excellent comfort

� No edge awareness or movement

� Excellent vision – especially at night


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� Excellent vision – especially at night

� No problems on windy days

� Excellent stability – total security

� Easier to handle, more difficult to lose

� More reliable wearing times

Very comfortable, stable with excellent vision

� Minisclerals - manufacturers

� Eyecon miniscleral – Capricornia Contact Lenses

� Gelflex


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� Gelflex

� Contact Lens Centre – SSMax

� KATT – Capricornia Contact Lenses

� Eyecon miniscleral (Capricornia)

� Trial set - base curves: 6.8 – 8.2 mm

� Diameter: 16.00 mm


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� Diameter: 16.00 mm

� Periphery: standard or flat

� Material: Boston XO

� Fit assessed by measuring tear film depth

� Optimal clearance: 180 – 270 µ

� Avoid blanching of conjunctival vessels

� Eyecon miniscleral – standard or flat edge

� 7.8 (16.00) -1.00, standard edge VA 6/10+2


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� Eyecon miniscleral

� staining


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� Minisclerals - measurements

� Topography – only out to 8mm

� Corneal sagittal height


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� Standard RGP lens curves are based upon the

corneal curvature

� Miniscleral fitting is based on sag, so a flatter

base curve (7.8mm) may vault over a cornea

with maximal curve (6.8mm), due to a shallow

anterior chamber

� Trial lens fitting essential - base curve and sag

� Estimation of anterior chamber depth – The Smith Method

� The Smith method allows the measurement of the anterior chamber depth.

� Turn the beam to horizontal


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� Turn the beam to horizontal

� Illumination arm set at 60 degrees

� Use the right eyepiece for the right eye measurement

� Narrow beam

� High illumination

� Minimal beam length

� Focus on anterior lens capsule

� Observe separate out of focus image on endothelium


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� Estimation of anterior chamber depth – The Smith Method

� Extend length of beam until the images meet

� Measure the length by reading off the slit lamp


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� Measure the length by reading off the slit lamp

� Conversion factor of 1.4 x reading = central anterior chamber depth in mm

� E.g. 3.860, 4.250, 5.154

� Fitting philosophy is based on matching the sag of the eye at a chord of 15mm to

that of the lens with an allowance for apical clearance


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� Parameters

� Base curve/optic – cornea zone

Transitional curves - limbal zone, adjusts differences in


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� Transitional curves - limbal zone, adjusts differences in

elevation from mid periphery and past the limbus

� Peripheral curves - scleral zone – allows for adjustment

of alignment on the sclera, to reduce or increase edge

clearance


� Fitting

� Measure corneal sag and select trial lens with next highest sag

� Anaesthetic is optional, can be useful for the patient to experience the lens

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� Anaesthetic is optional, can be useful for the patient to experience the lens

� Must be inserted bubble free

� Fill lens with saline, add fluorescein

� Inserted using large suction cup holder as a support

� Observe bearing and clearance, tear thickness profile across the lens

� If initially okay, review after 30 minutes

� Removed with DMV-45 assisted by lower lid manipulation


� KATT (Capricornia)

� Development of KATT from Eyecon miniscleral

� Increased knowledge of scleral curvature, better alignment

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� Incorporating anterior chamber depth, sag measurements

� Introduction of tangential curves to alter sag

� Material Boston XO2 (Dk 141)

� Tear film: Central clearance – 300 µ, Limbal clearance - 200 µ

� Known Lens centre thickness (300 µ)

� Trial set: 6.0 mm (sag 5.715) to 8.0 mm (sag 3.9844)



� Spherical or aspheric central

optic zone (10mm)

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� Tangent curve that runs parallel

to the ocular surface (14mm)

� Second tangent curve zone that

allows for sag variation

� Peripheral curve that meets

the sclera (15.0- 16.5mm)


� KATT (Capricornia) - Second tangent curve zone that

allows for sag variation

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� Patient RU: Diagnosed PMD @ 30, wearing soft c/l's, accountant

� Very poor reaction to RGP c/l’s in late 30’s – very uncomfortable, will not

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� Very poor reaction to RGP c/l’s in late 30’s – very uncomfortable, will not

try again

� Rx: R +2.50/-7.50x85 VA 6/8-2 L +4.00/-4.50x73 VA 6/8+2 (variable)

� Vision with current soft lenses: R 6/24+2 L 6/24-

� Topography R 7.17 @ 169, 9.44 @ 79


� KATT (Capricornia) - Patient RU

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� KATT (Capricornia) - Patient RU, trial lens inserted with fluorescein

� RE: KATT 7.8 (16.50), sag: 3.9674 after 30minutes

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� KATT (Capricornia) - Patient RU

� RE: KATT 8.0 (16.50) sag: 4.1133 7.0 (16.50), sag: 4.4444

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� KATT (Capricornia) – Fluorescein added to external tear layer, compare lens

thickness (300µ) to tear lens thickness

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� Central NasalTemp

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� KATT (Capricornia) - Patient RU - Staining after 11 hours wearing time

� V with KATT: 6/6-2

� Regular daily wear

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� Regular daily wear

� Up to 16 hours/day

� Excellent comfort

� No difficulty handling lenses


� KATT (Capricornia) - Patient NW: KC, bilateral grafts, wearing RGP c/l's

� L wearing reverse geometry bitoric 8.2x6.8(10.5) spherical periphery- successful

� V with c/l: 6/15, with over refraction: 6/8-

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� Lost RGP lens, lab unable to duplicate fitting or Rx (poor VA) + discomfort


� KATT (Capricornia) - Patient NW: graft, Topography L 6.48 @ 19 / 8.61 @ 109

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� KATT (Capricornia) - Patient NW: 6.2(16.50), sag: 5.1969

� V with c/l: 6/6-2

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� KATT (Capricornia) - Patient NW: 6.2(16.50), sag: 5.1969

� Staining after wear

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� KATT (Capricornia) – Patient AR - KC - previously worn soft c/l's, LE graft

@ 22, farm labourer

� Topography: L 6.43 @ 56 / 7.70 @ 146

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� KATT (Capricornia) – Patient AR - LE graft 6.5(16.50), sag: 4.8486

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� KATT (Capricornia) – Patient AR - LE graft

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� KATT (Capricornia) – Patient AR - KC - RE

� Topography: R 7.13 @ 70 / 7.77 @ 80

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� KATT (Capricornia) – Patient AR – RE KC

� CLC Centra PGA

� 7.2(10.1), V with c/l: 6/10-2

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� 7.2(10.1), V with c/l: 6/10-2



� 7.2 sag: 4.4444

� V with c/l: 6/8

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� V with c/l: 6/8



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� KATT (Capricornia) – Patient AB – KC - R graft, wearing Eyecon

miniscleral in LE

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� KATT (Capricornia) – Patient AB – R graft

� After suture removal: Rx RE +2.50/-9.50x167 VA 6/8-

� Topography: R 6.92 @ 78 / 8.77 @ 168

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� KATT (Capricornia) – Patient AB – R graft 6.5(16.50), sag: 4.8486

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� KATT (Capricornia) – Patient SR – KC – bilateral grafts, LE ICL, LE intense

chronic discomfort, LE Rx -6.50 VA 6/15

� Topography: R 6.72 @ 173 / 7.36 @ 83

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� KATT (Capricornia) – Patient SR – LE intense chronic discomfort

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� KATT (Capricornia) – Patient SR – LE intense chronic discomfort

� V with L c/l + over refraction: 6/6-2

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� KATT (Capricornia) – Complications

� Excessive conjunctival bearing

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� KATT (Capricornia) – Complications

� Conjunctival hyperaemia Faint diffuse spk staining

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� SSMax (Contact Lens Centre)

� 5 zones - Cornea zone, Transitional curves and Peripheral curves

� Overall Diameter: 15.80 mm

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� Overall Diameter: 15.80 mm

� Material Boston XO (Dk 100)

� Trial set: 6.0 (sag 5.03) – 8.2 (sag 3.54)

� Central clearance: 45 – 50 µ

� Edge width: 0.75 – 1.0 mm


� SSMax (Contact Lens Centre)

� Each curve is defined by eccentricity and width and can be varied to

increase or reduce the alignment profile across the lens

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increase or reduce the alignment profile across the lens

� Edge lift to promote tear exchange

� Design Configurations – Spherical, Toric Periphery, Back Surface Toric,

Front Surface Toric, Bitoric, Bi-Sym, Quad-Sym


� SSMax (Contact Lens Centre) – Patient SR – KC - R graft

� Topography: R 6.93 @ 53 / 8.37 @ 143

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� SSMax (Contact Lens Centre) – Patient SR – R graft

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� 6.4 sag: 4.60 6.6 sag: 4.45

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� 7.8 sag: 3.71 7.2 sag: 4.04

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� 7.2 sag: 4.04, V with c/l: 6/8+2, over: +1.50/-2.00x45 VA 6/5

� Front Surface Toric ordered – 7.0 base

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� Minisclerals - summary

� Another viable option for KC and corneal graft fitting

� Design development is ongoing


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� Effective communication with manufacturers is essential when

using complex designs

� Better edge design required to facilitate tear exchange and reduce

conjunctiva compression

Very comfortable, stable with excellent vision

Documents

New options for the intolerant RGPwearer: Minisclerals€¦ · Lost RGP lens, lab unable to duplicate fitting or Rx (poor VA) + discomfort. Keratoconus and Corneal grafts –Miniscleral