Transcript fellow eyes of unilateral keratoconus are they really normal? (580)

Fellow eyes of “Unilateral Keratoconus”…
Are they really normal?
Dr. Prema Padmanabhan
Ms. Aiswaryah
Ms. Abinaya
Medical Research Foundation
Chennai, India
Poster ID: 580
Authors have no Financial Interest
Why is the detection of Keratoconus
so important ?
3 years
Post-Lasik
Pre-op – Normal
topograph
Post-Lasik ectasia
Unilateral Keratoconus - Defined
One eye : Frank Keratoconus
Fellow eye : No Topographic
Clinical / Topographic / Both
features of Keratoconus
AIM of the study
• Is the fellow eye of a patient with “Unilateral
Keratoconus” really normal?
?
• Is there a “Sub-topographic” stage of the disease
which could be detected by aberrometry?
Material and Methods
• Prospective study of 62 patients diagnosed as “Unilateral
Keratoconus” by Corneal Topography
• 75 age-matched and K-matched normal eyes served as
“Controls”
• Corneal topography with TMS-4
• Corneal aberrations calculated by VolCT at 7mm OZ
• Ocular aberrations measured by Allegretto Wave
Analyzer at 7mm pupil diameter
• Measurements repeated after mean follow-up of 17 mths
(range 6 to 36 mths)
Results
Parameters
Keratoconus
Fellow
“Normal Eyes”
Normal
(Controls)
N
62
62
75
Age (yrs)
24.5(+4)
24.5(+4)
25.5(+6)
Refractive Cylinder (D)
-4.25(+0.3)
-0.89(+0.8)
-0.4(+0.4)
Clinical features
Present
Absent
Absent
Mean Sim K (D)
54.87(+0.7)
44.3(+1.4)
43.9(+1.8)
Topography indices
Positive
Negative
Negative
Mean Pachymetry (m)
474 (+38.4)
504 (+26.1)
546.6(+24.8)
Results
Corneal aberrations
Ocular
Aberrat
ions
Keratoconus
Fellow
“Normal
Eyes”
C7
-0.73 (+0.36)
-0.11 (+0.08)
C12
-0.08 (+0.02) -0.03 (+0.015)
Normals
0.01 (+0.02)
Sph.ab.(C12)
0.08 (+0.05)
Vertical coma(C7)
Ocular aberrations
Most predominant HOA : C7
Keratoconus &fellow eyes : -ve C12
Sph.ab.(C12)
Vertical coma(C7)
Pair-wise analysis: HOA similarity:
49 of 62 eyes (79.03%)
Proposed Criteria:
“Sub-topographic Keratoconus”
• Discriminant Analysis:
40.3% of eyes classified as “Normal” by
Topography were reclassified as
1
0.8
Sensitivity
Criteria :
C7 >-0.27m,
C12 >-0.018m
0.6
Sensitivity: 88.4%
0.4
Specificity: 83.1%
0.2
0
0
0.2
0.4
“Suspected Keratoconus” by
Aberrometry
1-specificity
0.6
0.8
Ocular aberrations – follow-up
Progression in Topography
Clinically : Normal
Topography : Normal
Aberrometry : Suspect
6 months
later
Clinically : Normal
Topography : Suspect
Aberrometry : Suspect
Progression in HOA
Clinically : Normal
Topography : Normal
Aberrometry : Suspect
6 months
later
Clinically : Normal
Topography :Suspect
Aberrometry : Progress of disease
Conclusions
• Corneal & Ocular aberrations are often
abnormal in fellow “Normal” eyes of “Unilateral
Keratoconus”
• Aberrometry may be a useful tool to detect the
sub-topographic stage of the disease
• We recommend that aberrometry be performed
on all patients being screened for Refractive
surgery