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5/9/2019
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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