Date post: | 13-Apr-2017 |
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BY:
NOOR MUNIRAH BINTI AWANG ABU BAKAR
OPTOMETRISTMOC: O-0869
SCLERAL LENS
OUTLINES
Scleral LensTerminology AnatomyHistoryIndicationsDesignLens fittingAdverse eventsPatient complianceFuture hope
Scleral Lens
Also known as: Haptic lens‘haptic’ = sense of touch
A large diameter rigid contact lens that cover the entire surface & rest on sclera. Diameter: 15.0mm to 25.0mm
Minimum or no contact on the cornea
Terminology
Ocular Anterior Anatomy
• Average corneal diameter is 11.8mm
•The maximum diameter a scleral lens can have is 24mm
History
When it starts?
Scleral lens is used to fit on corneal diseases (irregular corneas)
Two forms of manufacturing lens(a) Spin cast - mold(b) Lathe cut – custom made
Scleral lenses are lathe cut High cost making it unpopular
Why is Scleral Lens not popular?
Expensive Large lens diameter Difficult to fit Fragile Lack of expertise to fit Complications when patient wear it
overnight
Indications
Indications
1. Vision Improvement
Mainly for corneal ectasia cases Primary : Keratoconus, keratoglobus, PMD Secondary : Post refractive surgery (LASIK,LASEK,
PRK) Other conditions: post trauma, corneal scar due to
infection To restore and improve vision
Indications
2. Corneal protection In 2 conditions:
Severe ocular disease (Sjogren, Steven Johnson, Graft versus host dx)
Incomplete lid closure (eyelid coloboma, ectropion, exophthalmos, nerve palsies)
Help by reducing corneal exposure to air (not to close the eye)
Benefits: To relieve symptoms of pain & discomfort Keep ocular surface moist in severe dry eyes by fluid
reservoir retention Slow the progression of corneal disease and delay the
need for surgery Decrease risk of scarring
Indications
3. Cosmetic In prosthetic eye (not widely use in Malaysia due to
its cost) Full ocular prostheses Partially prostheses
Use on: aniridia (reduce glaring), albinism, trauma,nanophthalmos
4. Sport More secured – reduce risk of loss Provides stable vision and comfort
Indications
5. Drug delivery Scleral lens has tear reservoir Instill drug onto bowl of scleral lens RGP is not suitable for drug delivery, due to lens
movement
6. Normal eyes Very common in other country Corneal lens cannot fit well It gives less complication
Design of scleral lens
Design of scleral lens
1. Optical zone Minimal/not contact with cornea (RGP: contact) Large size (RGP: smaller) Give optical effect Surface:
Anterior surface: Aspheric design to reduce photophobia and aberration
Posterior surface: Same shape as cornea Sagittal height of scleral lens is higher than RGP sagittal
height Available in toric (but not available in Malaysia)
Design of scleral lens
2. Transitional zone Only scleral lens has transitional zone Connect sclera and sclera It set the sagittal height
Changing sagittal height means change the transitional zone (flatter or steeper)
Depends on the shape of the sclera The transitional zone for small diameter ScCL may rest on
limbal area, not for larger diameter ScCL. Range of transition zone: 0.5mm to 2.0mm.
Design of scleral lens
2. Transitional zone Scleral shape
Referring to cornea, limbus and sclera Affect the ScCL fitting
Involve the transitional and landing zone The sclera can be evaluated using:
Pentacam Anterior segment OCT
Type of limbal profile:1. Gradual convex2. Gradual tangential (common)3. Convex concave4. Marked convex (common)5. Marked tangential
1 2 3 4 5
Design of scleral lens
2. Transitional zone Limbal angle and scleral angle
What: This is angle between iris & cornea Temporal angle larger than nasal angle (T≠N) ScCL easily decentred to the nasal However, it would not affect vision because the optical zone
is large.
Design of scleral lens
3. Landing zone (Haptic zone) Area of ScCL that rest on the sclera Important to know:
Size of landing zone Angle of landing zone
Landing zone as back surface toric: change the thickness at one side
Can make peripheral toric by thinning the edge like prism ballast.
Increase diameter of landing zone, make it more comfortable to wear as less movement produced
Scleral lens fitting
Scleral lens fitting
4 steps approach
Scleral lens fitting
1. Optical/ Clearance zone diameter Optical zone important to provide good optical
outcome and corneal clearanceClearance zone = optical zone + transition
zoneUsually 0.2mm larger than HVIDSize depends on lens designsCan be altered to improve corneal and limbal
clearance
Scleral lens fitting-Lens insertion
Scleral lens fitting
2. Central and limbal clearanceUp to 600 microns of corneal clearance can be easily
achieved if needed centrally.Clearance of 200–300 microns is usually considered
sufficient, but this can easily go up to 500 microns if desired with the end stage large diameter lenses.
The terms “flat” and “steep” are substituted with increase or decrease in sagittal height instead. Increasing the sagittal height of the lens causes the lens to “lift” off the
eye, increasing the clearance or vault of the lens.Sagittal depth differs with the condition:
Ectasia needs larger than post-corneal grafts Ocular surface disease management requires large sagittal height
Scleral lens fitting
Central and limbal clearance evaluation Start with low sagittal height and gradually increase height to desired
clearance A green fluorescein pattern will be visible. Use a thin optical section with brightest illumination setting at a 45 degree
angle If CCT known, compare corneal thickness to tear layer thickness to estimate
clearance If CCT not know, assume a 530micron central cornea and 650 micron at
periphery (Doughty 2000) and compare to the slit.
Scleral lens fitting
Limbal clearance Complete and generous limbal clearance is necessary
to ensure tear circulation and prevent erosive damage to the limbal epithelial cells.
If very little fluorescein observed in the limbal area of the lens, then the lens is too small and should select a larger diameter. Scleral lens with inadequate limbal clearance
Scleral lens with complete limbal clearance
Scleral lens fitting
3. Landing zone alignment The landing zone should rest evenly on the scleral conjunctiva with
the edge appearing just above the conjunctival epithelium.
The lens should not move with blinking. Moving lens cause discomfort to the patient. Can correct by tightening the landing zone.
No fluorescein will be visible under a well-fit landing zone except at the edge. A ring of bearing on the inner part of the landing zone indicates a flat
landing zone A ring of bearing on the outer part of the landing zone indicates a steep
landing zone Increasing the size of the landing zone relieves pressure if needed.
Scleral lens fitting
4. Lens edge lift Assess lens edge lift after 30 minutes of lens installation during
fitting process. Also assess lens edge after 3-4 hours of lens wear.
Too much edge lift : Cause lens awareness and discomfort Action: Decrease the edge lift by changing the landing zone angle or by
choosing a smaller landing zone radius of curvature. Low edge lifts:
Leave a full or partial impingement ring on the conjunctiva after lens removal Two easy methods
Observe the edge lift with white light & how much it “sinks” into the conjunctiva
Push-in method -preferred if the lens showed some mobility Remove lens and evaluate surface with fluorescein staining
Adverse events
Adverse events
Adverse events
Patient compliance
Patient compliance:1. Hygiene
Cleaning kit same as RGP, must using protein cleaner. If deposit on lens present, first see Giant papillary
Conjunctivitis.
2. Sleeping with Scleral CL Pt love to wear lens overnight. Advice patient not to wear scleral lens extendedly to
avoid complications.
Future Scleral Lens
Would you consider scleral lens in future? YES.
Good alternative for irregular cornea Less complications Better corneal health
Future Scleral Lens
Thank You