naomi r. goldberg, md phd kenneth j. wolf, md eric j. wolf, md facs the authors have no financial...
TRANSCRIPT
Naomi R. Goldberg, MD PhDNaomi R. Goldberg, MD PhD
Kenneth J. Wolf, MD Kenneth J. Wolf, MD
Eric J. Wolf, MD FACSEric J. Wolf, MD FACS
The authors have no financial interest in the subject matter of this poster.
Comparison of central corneal thickness measurements from contact ultrasound pachymetry
and non-contact specular microscopy
Purpose:Purpose:
To assess the relationship of central To assess the relationship of central corneal thickness (CCT) measurements corneal thickness (CCT) measurements taken from the non-contact Tomey taken from the non-contact Tomey EM3000 Specular Microscope system to EM3000 Specular Microscope system to those measured by ultrasound (US), the those measured by ultrasound (US), the current standard for pachymetry. current standard for pachymetry.
Background:Background:
Central corneal thickness measurements are Central corneal thickness measurements are important factors in multiple ophthalmic important factors in multiple ophthalmic evaluations.evaluations.Intraocular pressure measurements made by Intraocular pressure measurements made by applanation tonomety are overestimated in thicker applanation tonomety are overestimated in thicker corneas and underestimated in thinner corneas.corneas and underestimated in thinner corneas.Preoperative central corneal thickness is used to Preoperative central corneal thickness is used to determine the residual stromal bed following laser determine the residual stromal bed following laser vision correction to insure a stromal bed that is vision correction to insure a stromal bed that is sufficient to prevent postoperative ectasia.sufficient to prevent postoperative ectasia.
Methods:Methods:
One specular microscope scan, followed by three One specular microscope scan, followed by three ultrasonic measurements of seventy-six eyes from thirty-ultrasonic measurements of seventy-six eyes from thirty-eight patients were recorded. Corneas were eight patients were recorded. Corneas were anesthetised with topical proparacaine before performing anesthetised with topical proparacaine before performing the contact pachymetry. the contact pachymetry.
Ultrasonic measurements were performed using the Ultrasonic measurements were performed using the Accutome AccuPach V and specular microscopy Accutome AccuPach V and specular microscopy measurements were made using the Tomey EM3000 measurements were made using the Tomey EM3000 Specular Microscope. Specular Microscope.
All patients had not used contact lenses for at least 24 All patients had not used contact lenses for at least 24 hours prior to evaluation.hours prior to evaluation.
InstrumentsInstruments::
Tomey EM 3000Tomey EM 3000 Accutome AccuPach VAccutome AccuPach V
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
Specular Microscopy Ultrasound Pachymetry
Mean CCT (m) 540.4 544.5
Range CCT (m) 462-624 480-631
Mean Difference (m) 4.1P-value 0.007
ResultsResults::
450
500
550
600
650
0 10 20 30 40 50 60 70 80
Eye
CC
T (
m
)
Specular MicroscopyUltrasound Pachymetry
Correlation between individual measurements of CCT from Ultrasound Pachymetry and Specular Microscopy
Distribution of difference between CCT measured by ultrasound (US) pachymeter and Tomey Specular Miscroscope
vs. their average
-30
-20
-10
0
10
20
30
40
50
450 500 550 600 650
Average US Pachymetry and Specular Miscroscopy Measurement of CCT (m)
Dif
fere
nce
US
Pac
hym
etry
and
Spe
cula
r M
icro
scop
y (
m)
+1SD
-1SD
+2SD
-2SD
Mean difference: 4.1
Specular Microscopy Ultrasound Pachymetry
Mean CCT <544.5 (m), n=37 513.7 516.1Mean difference (m) at CCT<544.5 2.4P-value 0.29
Mean CCT >544.5 (m), n=39 565.8 571.5Mean difference (m) at CCT>544.5 5.6P-value 0.01
Sub-group analysis, using mean Sub-group analysis, using mean Ultrasound CCT as cutoffUltrasound CCT as cutoff
Conclusions:Conclusions:There exists a strong correlation between corneal There exists a strong correlation between corneal thickness measurements made using contact thickness measurements made using contact ultrasound pachymetry and non-contact specular ultrasound pachymetry and non-contact specular microscopy.microscopy.The correlation is stronger with thinner corneas The correlation is stronger with thinner corneas and weaker with thicker corneas.and weaker with thicker corneas.Non-contact modalities for determining central Non-contact modalities for determining central corneal thickness may be appropriate for corneal thickness may be appropriate for pachymetry for glaucoma evaluations and possibly pachymetry for glaucoma evaluations and possibly for laser vision correction evaluations, though the for laser vision correction evaluations, though the latter requires a more exact measurement and may latter requires a more exact measurement and may benefit from multiple measurements.benefit from multiple measurements.