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Managing Irregular Astigmatism– Cataract Surgery

SHERAZ DAYAMD FACP FACS FRCS(Ed) FRCOphth

Financial DisclosureCompany Code

1. Abbott Medical Optics Inc. S

2. Bausch + Lomb C,L

3. Carl Zeiss Meditec C

4. Clarvista C

5. Ellex L

6. Excellens C, O

7. LinCor Biosciences C

8. Lumenis C

9. Medicem C

10. Nidek, Inc. C,L

11. Omidria C

12. Physiol L

13. PRN O

14. STAAR Surgical C

15. Strathspey Crown C

16. Scope Pharmaceuticals C

17. Rayner C

C = Consultant / Advisor

E = Employee

L = Lecture Fees

O = Equity Owner

P = Patents / Royalty

S = Grant Support

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Irregular Astigmatism – consequences…

• Poor vision

• Biometry

– Challenging

– Errors

– IOL miscalculation

• Patient (& Surgeon) disappointment

Managing Irregular Astigmatism

• Causes of Irregular Astigmatism

• Identification - Diagnostics

• Principles of Management

• Case examples

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Irregular Astigmatism - CAUSES

Irre

gula

rity

Tear Film

Epithelium

Sub-epithelial

Stromal

Tear Film

• Dry eye

– Underproductive

– Evaporative

– Inflammation

• Irregular tear film

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Impact of Tear Film on Biometry

Epitropoulos AT, Matossian C, Berdy GJ, Malhotra RP, Potvin R. Effect of tear osmolarity on repeatability of keratometry for

cataract surgery planning. JCataract Refract Surg. 2015 Aug;41(8):1672-7. doi: 10.1016/j.jcrs.2015.01.016.PubMed PMID: 26432124

17% > 1.0D difference in Keratometric cylinder between 2 visits

10% > 0.50D in calculated IOL power

Irregular Astigmatism - EPITHELIAL

• Anterior Basement Membrane Dystrophy

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Irregular Astigmatism: SUB-EPITHELIAL

• Salzmann’s nodular degeneration

• Scarring Bowman’s

• Reiss-Bücklers

Irregular Astigmatism: STROMAL

• Change in Corneal Shape– Ectatic Disorders

– Stromal Scarring

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Irregular Astigmatism – Corneal Shape

• Asymmetric astigmatism • Non- Orthogonal

Diagnosis of Irregular Astigmatism

CLINICAL EVALUATION DIAGNOSTICS

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CLINICAL EVALUATION

• Cornea

– Shape

– Clarity

– Surface

• Fluorescein stain

– Lid wiper action

– Distribution

Tear Film

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DIAGNOSTICS

TOPOGRAPHY

• Reflective

– Placido based

DIAGNOSTICS

• Placido systems

• Placido combined with Aberrometry

– OPD 3 (Nidek)

– iTrace (Tracey Technologies)

– KR1W (Topcon)

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3-Dimensional Diagnostics

Shape analysis and influences

- elevation

- posterior cornea

- thickness

• Scanning slit (Orbscan)

• Scheimpflug (Pentacam, Galilei)

“Dry Eye”

Evaluate cause & treat

Once stable – repeat IOL calcsDRY EYE

EVAPORATIVE

INFLAMMATION

AQUEOUS DEFICIENT

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Anterior Basement ”Dystrophy)• Pathology: Duplication of Basement membrane

• Commonly in association with Meibomian Gland Disease– ? Related to inflammation

• Irregularity best removed– Epithelial debridement

– Phototherapeutic keratectomy (PTK)

ABMD• IOL calculations 6 weeks later

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Salzmann’s Nodular Degeneration

2X speed

Bowman’s

Hyaline material

Salzmann’s Nodular DegenerationPRE-OP POST-OP

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Non-orthogonal Astigmatism

Keratoconus – commonest cause

• What was the Best SPECTACLE corrected vision before cataract ?

– If good (6/12 or better) – consider a TORIC IOL

– If not good, consider changing corneal shape

Non-orthogonal Astigmatism

Ch

ange

co

rne

al s

hap

e

Intracorneal rings

Topolink with CXL

Corneal Transplant

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CXL and Topographic PRK

POST-OP PRE-OP

I-S ratio 6.9 I-S ratio 52.1

SE -2.25 DS SE -0.75 DSCyl 2.50 D Cyl 3.50 D

UCVA 6/18 UCVA 6/60BCVA 6/10 BCVA 6/30

Courtesy

Arthur Cummings

Intracorneal Rings

Ferrara Intacs

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Toric IOL What axis to use for implantation ?

73 deg90 deg 97 deg

102 deg

Use Corneal derived aberrometry

Polynomial for astigmatism

(Z2±2 S2±2)

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Lens orientation

Post Toric lens implant

121 deg 127 deg

Managing Irregular Astigmatism in Cataract Surgery

• Principles

– Evaluate the source of the problem

– Address to reduce magnitude of irregularity

– Proceed to IOL Calculations and Surgery:

When astigmatism is compatible with potential good vision

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Thank you…

www.centreforsight.com