scleral lenses

Question 1

Scleral lens diameter can range between ..

Answer 1

15-25mm
Average corneal diameter is 11.8m

Question 2

what are scleral lenses

Answer 2

Large diameter GP that vault over the entire cornea and rest on the sclera
-Minimum or no contact on the cornea
-Can be used to treat a number of diff conditions by vaulting over an irregular or diseased corneal surface

Question 3

Different scleral categories

Answer 3

-corneo-scleral
-semi-scleral
-mini-scleral
-scleral

Question 4

function of scleral lens

Answer 4

-maintains corneal hydration
-masks irregularities in corneal shape
-reduce pain from corneal diseases

Question 5

features of scleral lenses that make them different from GPs

Answer 5

-The large size makes them more stable on the eye which contributes to increased comfort
-does not touch the cornea / sits on sclera instead
-diameter is much bigger
-less movement

Question 6

canidadtes for scleral lenses

Answer 6

-corneal ectasias
~keratoconus
-altered corneal shape
-severe dry eyes
-high refractive errors

Question 7

why are scleral lenses not popular?

Answer 7

-lack of comfort or expertise to fit
-lack of appropriate technology to fit accurately
-expensive
-fragile

Question 8

3 zones of scleral lens design

Answer 8

-haptic surface AKA landing zone
-optical zone
-transitional zone

Question 9

optical zone

Answer 9

-contains the refractive correction
-can be customized for optical vision: aspheric front surface. wavefront guided
-responsible for the creation of a vault - a liquid filled space over the cornea

Question 10

what is the term for vault

Answer 10

sagittal depth
-space between the scleral lens and the cornea
-increase the sag depth causes the lens to “lift” off the eye, which increases the vault of the lens

Question 11

transitional zone

Answer 11

-connects the optic and landing zones
-may contain multiple curves
-can be customized to adjust the fluid reservoir depth over the mid-peripheral cornea and limbus

Question 12

landing zone / haptic zone

Answer 12

-contacts the conjunctival tissue overlying the sclera
-the size and angle can be customized
~influences characteristic like seal off, centration, suction

Question 13

technology for sclera lens fitting

Answer 13

-anterior segment OCT
-scleral topography and tomography
-impression based lenses

Question 14

anterior segment OCT

Answer 14

-most practitioners would NOT fit scleral lenses w/o an anterior segment OCT
-the fitting relationship cannot be fully evaluated with biomicroscopy alone

Question 15

what can anterior seg OCT assess?

Answer 15

-sag depth
-limbal clearence
-landing zone position
-corneal health

Question 16

scleral topography and tomography

Answer 16

-maps out the shape of the sclera
-allows for the creation of a customized scleral lens
-results in a highly accurate scleral lens fit
-topography = 2D image
-tomography= 3D image

Question 17

impression based lenses

Answer 17

creates an exact replica fo the corneal surface from an impression

Question 18

intial lens selection based on two things..

Answer 18

-diagnostic fitting
-empirical fitting

Question 19

diagnostic fitting

Answer 19

Must consider
-overall lens diameter
-sag depth
-posterior lens surface profile

Question 20

empirical fitting

Answer 20

-provide clinical finding using clinical software or speaking with a consultant and they design the lens for you

Question 21

4 steps to scleral lens evaluation

Answer 21

1. central clearance
2. limbal clearance
3. landing zone alignment
4. edge lift

Question 22

central clearance or vault evaluation

Answer 22

-OCT
-target 200-300 micrones of central clearance but can go higher.
-slit lamp
-use scleral lens fit scales
-adjust sag depth as needed
-increased sag depth = increased clerance / making a lens “steeper”

Question 23

limbal clearance

Answer 23

-adequate limbal clearance is necessary to protect the hydrate and protect limbal cells

Question 24

two types of limbal clearnece

Answer 24

1. Adequate
   -fluroscein at limbal area
2. Inadequate
   -beraing - black at limbal area

Question 25

landing zone alignment

Answer 25

-the landing zone edge should be just above the conjuctiva
-lens should NOT move with blink
-reduce movement by tightening the landing zone
-fluroscein should be visible at the edge of the landing zone

Question 26

edge lift

Answer 26

-excessive edge lift ; fix by changing the landing zone angle or radius of curvature
-inadequate edge lift / “digging into”
-often called embedded edge or toeing
-causes impingement and conjuctival blanching

Question 27

scleral lens complication

Answer 27

-scleral deposits and fogging
-conjuctival prolapse
-seal off

Question 28

scleral deposits and fogging

Answer 28

-occurs when there is accumulation of debris in the tear film reservoir during scleral lens wear
-visible with slit lamp exam or OCT

Question 29

treatment of scleral deposits and fogging

Answer 29

-remove, rinse, re-insert the lens
-improve the ocular surface by treating dry eyes
-reduce the sag depth

Question 30

conjuctival prolapse

Answer 30

-occurs when loose perilimbal conjuctival tissue is pulled between the scleral lens and the corneal limbus
-on slit lamp exam, appears as pink/white tissue at the edge of iris

Question 31

treatment of conjuctival prolapse

Answer 31

-improve landing zone alignment
-reduce limbal reservoir thickness

Question 32

seal off

Answer 32

• a tight fitting scleral lens can cause bearing or impingement on the conjuctival blood vessel
  -red eye with a visibile white outer ring around the edge of the lens
  -can lead to lens discomfort or headahces

Question 33

treatment of seal-off

Answer 33

flatten the landing zone curve

Question 34

scleral lens tools for inserting

Answer 34

-fingers
-plunger device (DMV)
-ring device
-DMV stand

Question 35

scleral lens insertion

Answer 35

-rinse lens with a preservative free saline solutino
-set the lens on the center of the plunger
-fill the lens forming a convex shape.
-bend over and look straight down while holding your eyelids wide open, set the lens on the centre of your eye
-blink, make sure the lens is centered and comfortable
-air bubbles can cause discomfort, poor vision and unusual glare, reapply if any bubbles

Question 36

solutions to use for insertion

Answer 36

-single use perservative free saline solution
-buffer free
-buffered, non-preservative saline solution
-toxic response to buffer agents?

Question 37

tip for inserting scleral lens

Answer 37

lay mirror flat with towel underneath

Question 38

scleral lens removal

Answer 38

-insert 1-2 drops to help loosen the lens
-wet the plunger with 1-2 drops
-gentley attach the plunger to the edge (NOT THE CENTRE_ of the lens
-gently tilt up and out on the lens and carefully remove it

Question 39

scleral lenses cleaning and storage

Answer 39

-disinfection
~hydrogen peroxide CL solution
~multipurpose GP solution
~No rinsing/storage in water
-store lenses in CL case holder
-NO sleeping or overnight wear