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The Effect of YK Lens

onKeratoconus

Ji-Eun Lee 1 , Jong Soo Lee 1 , Young Ki Park 2

Department of Ophghlamology, College of Medicine,

Pusan National University 1 ,

Park Young Ki Eye Center 2

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Purpose

To introduce fitting characteristics and to evaluate

clinical efficacy and safety of multicurve YK lens for

keratoconus

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MethodsPatients

129 eyes

Patients with first prescription 77eyes

Patients having difficulties with their previous

lenses 52eyes

Keratoconus was diagnosed

by Rabinowitz indices on topography or

by characteristic objective findings

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MethodsLens characteristics

Multiple Peripheral Curves 5 curves in steeper BCChanging Parameters is Easy

Base curve

Peripheral curve 1

Peripheral curve 2

(Peripheral curve 3)

Edge

Dk = 4710 -11center thickness= 0.1mm (-10D)

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YK1 YK2 YK24 YK25

Total Dia 8.7mm TotalDia

8.7mm TotalDia

8.7mm TotalDia

8.7mm

Power -20.00 Power -20.00 Power -4.00 Power -4.00

BCR 5.00 BCR 5.20 BCR 7.50 BCR 7.60

OZD 4.7 OZD 4.7 OZD 6.5 OZD 6.5

PCR1 5.50 PCR1 5.70 PCR1 8.30 PCR1 8.40

PZW1 0.5 PZW1 0.5 PZW1 0.4 PZW1 0.4

PCR2 6.00 PCR2 6.20 PCR2 9.30 PCR2 9.40

PZW2 0.5 PZW2 0.5 PZW2 0.4 PZW2 0.4

PCR3 7.00 PCR3 7.20

PZW3 0.6 PZW3 0.6 Edge 9.20 Edge 9.40 Edge 11.00 Edge 11.10

EW 0.4 EW 0.4 EW 0.3 EW 0.3

Total 25Size: 8.7mmBCR: 0.1mm increment except

first 3

BCR-OZD relationshipSmaller OZDSteeper Peripheral

Curves

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MethodsFitting methods

1. Initial BCR flat K minus 1/3 of theamount of Astigmatisms

2. With fluorescein pattern bychanging Trial Lenses

a. Minimal Apical Touch

b. Mid Peripheral Bearing

c. Edge3. Centering

4. Movement :1-1.5mm

5. Overrefraction : Prescribe diopters

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MethodsCase

K : 7.86/7.51Eccentricity : 0.60

TR (YK25) =Final

Lens

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MethodsModification of trial lenses

1. Determine Central BC First

2. If Edge High Lower type (-1,-2)

If Edge Low Higher type (+1,+2)

3. Oval Cone Enlarge OZD (0.5-1.0mm)

4. Decenter - Enlarge OZD (0.5-1.0mm)

5. High Inferior Edge Lift Steepen BC or Enlarge

OZD

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Results

Visual acuity20/40 or better : 82.1%2 Snellen lines :93.8%

Wearing timeAvr 12.2 hours (4-18)

Comfort

better thancomfortable: 90%

0

5

10

15

20

25

30

35

40

4550

4 6 8 10 12 14 16 18

Wearing time

N o .

o f e y e s

0

10

20

30

40

50

60

70

Very i rr ita ting I r ri ta ting Mi ld lyirritating

C omf or ta ble Ver ycomfortable

Comfort

N o .

o f e y e s

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ResultsKeratoconus progression between before andafter fitting

Changes of averages of Sim-K

First definite apical clearance lens No significant progression was found

Before fitting

P value

Sim-K max (D)Sim-K min (D) 46.626.

21 47.754.

23

Flatness(D)

2.983.31

2.853.02

55.725.25 53.125.49

After fitting

0.100.34

0.21

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Conclusions YK lens could provide

successful visual outcomewith comfort and

with no significant aggrevating

changes or significant progressionof disease

in keratoconus