Scleral Lens 9.4

Question 1

blown glass shells were used by:

Answer 1

1. Eugene Kalt (keratoconus) france
2. August Muller (myopia) germany
3. Eugen Fick (irregular astigmatism) switzerland

Question 2

satter’s veil

Answer 2

edema
vision problems

Question 3

is a corneal edema, there’s a change in refractive error because of the edema

Answer 3

sattler’s veil

Question 4

corneal lenses

Answer 4

 Rapid acceptance
 Importance of corneal metabolism and health understood
 Smaller lenses allowed better oxygen supply

Question 5

Indications for scleral lenses:

Answer 5

1. Patients involved in active water sports
2. Vigorous sports and dusty environments
3. People that require easier care, handling and wear
4. Greatly decentred pupils
5. Poorly centred lenses
6. Advanced keratoconus
7. High toric powers and prisms
8. Pathological and disfigured eyes
9. Aged (arthritis, tremors, etc)
10. Epithelial protection
11. Special effects for the performing arts

Question 6

sutures in cornea is called

Answer 6

corneal grafting/graft

Question 7

Disadvantages of scleral lenses

Answer 7

 Long fitting time
 Greater expense
 Limited availability
 Specialist fitters

Question 8

Types of scleral lenses

Answer 8

Preformed (trial fitting)
Impression (molded)

Question 9

advantages of Performed scleral lenses

Answer 9

Modifications simpler and easier to specify
Adequate limbal clearance easier to achieve

Question 10

disadvantages of performed scleral lenses

Answer 10

Difficult to fit highly toric or irregularly shapedeyes
Capital outlay for fitting set
Few manufacturers

Question 11

Performed scleral lenses sets

Answer 11

 Wide angle
 Spherical
 Off-set
 FLOM

Question 12

Ideal scleral lens fit

Answer 12

 Scleral zone a little flatter than alignment
 Edge zone slightly flatter again
 Fenestration in limbal zone between lids
 BOZR flatter than average Ks by » 1 mm
 Limbalzone»2mmwide,0.1-0.2mm clearance
 Air bubble should be present
 Tear exchange must be demonstrated

Question 13

Performed lens fitting techniques

Answer 13

1. Scleral zone
2. Optic zone fitting
3. Integrated fitting

Question 14

Scleral zone assessment

Answer 14

1. No corneal contact
2. Needs a steep BOZR
3. Range of lenses (total diameter, scleral zone radius)
4. Quality of scleral zone fitting

Question 15

Optic zone fitting flom

Answer 15

 Range of BOZRs: 8.00 to 9.50 mm
 Range of BOZDs: 13.00 to 14.75 mm
 Narrow, flat scleral zone (2 mm wide)
 Total diameter (approx. BOZD + 4 mm)
 Achieve optimum apical and limbal fitting
 Large trial set needed

Question 16

Integrated fitting

Answer 16

 Simultaneous fitting of optic transition and scleral zones
 Lenses made to specifications
 Vary BOZR, BOZD and SZR
 Trial fitting assessment
 Large trial set needed

Question 17

1800

Answer 17

 Concept of impression molding of the eye
 Little progress in the development of impression compounds

Question 18

scleral lenses Equipment and material

Answer 18

1. Molding powder
2. Molding shells
3. Syringe
4. Rubber bowl
5. Stainless steel spatula
6. Distilled water
7. Dental stone
8. Ocular irrigation solution

Question 19

Patient preparation

Answer 19

1. General advice on techniques
2. Use performed lens as a demonstration.
3. Topical anaesthetic

Question 20

Molding shells

Answer 20

1. Shells used to support the impression material and to handle the impression
2. Consider design specification of impression shells or trays
3. Decide on using injection vs insertion impression shells
4. Consider the size and location of holes
5. Note and properly use markings on the shell

Question 21

Impression technique

Answer 21

 Anaesthetic is used
 Mixture prepared
 Application
 Mixture hardens
 Mold is removed

Question 22

Basic fitting criteria

Answer 22

 Minimum apical clearance
 Limbal clearance
 Uniform scleral bearing pressure
 Small limbal bubble (if present)
 Settling back is likely

Question 23

Positive cast

Answer 23

 Dental stone used
 Cast hardens in the impression
 Orientation marks required
 Any roughness requires smoothing

Question 24

stages of production

Answer 24

1. flush fitting shell
2. Optic zone clearance
3. Optical power

Question 25

Oxygen permeable scleral lens

Answer 25

1. Lathe cut from large buttons
2. Can not be heat molded
3. High Dk materials available minimize corneal swelling non-fenestrated option

Question 26

flom stand for:

Answer 26

fenestrated lens for optic measurement

Question 27

Custom-made computer designed haptics

Answer 27

1. Rigid gas permeable scleral lenses
2. Junctionless posterior surface based on corneal topography data
3. Manufactured by a computer driven lathe

Question 28

Basic fitting criteria

Answer 28

 Minimum apical clearance
 Limbal clearance
 Uniform scleral bearing pressure
 Small limbal bubble (if present)
 Settling back is likely

Question 29

Factors necessary for good fit

Answer 29

1. Corneal clearance.
2. Fenestration necessary.
3. Influx of atmospheric O2 to the cornea and limbus.
4. Efflux of dissolved CO2.
5. Adequate tear layer thickness
6. Absence of bubbles, especially in the pupillary area
7. No perilimbal touch
8. Lens tolerance, good vision and continued comfort

Question 30

Symptoms and causes of scleral lens modification?

Answer 30

 Bubbles
 Froth
 Clicking
 Photophobia

 Lacrimation
 Blurred vision following lens removal
 Eyes stinging and burning
 Blurred vision upon insertion
 Transient blurring of vision
 Patient feeling sleepy and tired when wearing lenses
 Eyes constantly watering
 Complaints of haloes
 Complaints of mucus
 Eyes becoming red and injected Diplopia