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Analysis of the tear film by Analysis of the tear film by infrared thermographyinfrared thermography

(or “Some like it hot”)(or “Some like it hot”)

Philip B Morgan PhD MBCOPhilip B Morgan PhD MBCODepartment of Optometry and Vision Sciences, UMIST, ManchesterDepartment of Optometry and Vision Sciences, UMIST, Manchester

This work was supported by grants from Polymer Technology IncThis work was supported by grants from Polymer Technology Incand the Corneal Research Fund of Manchester Royal Eye Hospitaland the Corneal Research Fund of Manchester Royal Eye Hospital



Infrared thermographyInfrared thermography

Military, security applicationsMilitary, security applicationsMedical use since 1950sMedical use since 1950sBreast cancer, DVT, headacheBreast cancer, DVT, headacheRadiation Radiation αα T T44



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Analysis of the tear filmAnalysis of the tear film

IR absorbed by thin water filmsIR absorbed by thin water filmsOcular radiation mainly from TFOcular radiation mainly from TF

100% if thickness 40µm100% if thickness 40µm85% if thickness 10µm85% if thickness 10µm


are needed to see this pictureCORNEATEAR FILM 10µm

CORNEATEAR FILM 40µm

100%100%

85%85%



InstrumentationInstrumentation

6T62 Thermo Tracer6T62 Thermo TracerNEC San-ei, TokyoNEC San-ei, Tokyo

Frame time 0.25, 0.5, 1.0 secFrame time 0.25, 0.5, 1.0 secLiquid nitrogen cooledLiquid nitrogen cooledSensitivity = 0.025°CSensitivity = 0.025°C



InstrumentationInstrumentation

Thermograms in 256 coloursThermograms in 256 coloursStatistical manipulationStatistical manipulationData transferred to Apple MacintoshData transferred to Apple MacintoshImage manipulationImage manipulation



Normal eye temperatureNormal eye temperature

A typical thermogramA typical thermogramcoolest slightly below centrecoolest slightly below centreelliptical thermogramselliptical thermograms

32.10 ± 0.53°C32.10 ± 0.53°Clarge variationlarge variation

Inter ocular differenceInter ocular difference95% within 0.53°C95% within 0.53°C



(35.8)(35.8)

33.433.4

33.033.0

32.632.6

32.232.2

31.831.8

(29.4)(29.4)



Change in dry eyesChange in dry eyes

Absolute temperatureAbsolute temperatureRelative temperatureRelative temperatureChange with timeChange with timeAssessment of therapyAssessment of therapy



Dry eye patientsDry eye patients

36 recruited36 recruitedTBUT TBUT 10s or less10s or lessSchirmer test 10mm or less in 5 minSchirmer test 10mm or less in 5 minTear replacement therapyTear replacement therapyCompared against 25 normalsCompared against 25 normals



Dry eye patientsDry eye patients

Higher ocular surface temperatureHigher ocular surface temperature32.38 ± 0.69°C 32.38 ± 0.69°C vsvs 31.94 ± 0.54°C (p<0.01) 31.94 ± 0.54°C (p<0.01)

Due to hyperaemiaDue to hyperaemiaNote large variation in dataNote large variation in data



Dry eyeDry eyeControlControl

RTD 0.41 ± 0.20°CRTD 0.41 ± 0.20°C RTD 0.64 ± 0.28°C RTD 0.64 ± 0.28°C (p<0.001)(p<0.001)



Temporal changesTemporal changes

Over time, DE patients display:Over time, DE patients display:faster TBUTfaster TBUTfaster NIBUTfaster NIBUTfaster evaporation ratefaster evaporation rate

Temperature change?Temperature change?



ControlControl Dry eyeDry eye

00ss

11ss

22ss

33ss

44ss

55ss

66ss

77ss

More rapid coolingMore rapid cooling

More distorted patternMore distorted pattern



ControlControl Dry eyeDry eye

00ss

11ss

22ss

33ss

44ss

55ss

66ss

77ss

More rapid coolingMore rapid coolingDE -0.88 ± 0.23°C in 7sDE -0.88 ± 0.23°C in 7scont -0.21 ± 0.27°C in 7scont -0.21 ± 0.27°C in 7s

More distorted patternMore distorted patternTwo causes (?)Two causes (?)

increased evaporationincreased evaporationhigher initial temperaturehigher initial temperature



●

●●

● ●● ● ●

■ ■ ■ ■ ■ ■ ■ ■31.5

32.0

32.5

33.0

0 1 2 3 4 5 6 7

Time from eye opening (secs)

● Dry Eyes

■ Controls



● ●

●

● ● ●

■■

■

■ ■

■

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0 5 10 15 20 25 30

Time from instillation (mins)

● PVA

■ Saline



ConclusionsConclusions

Dry eye patients display:Dry eye patients display:warmer eyeswarmer eyesgreater temperature variationgreater temperature variationmore rapid coolingmore rapid cooling

Objective, non-invasive, rapidObjective, non-invasive, rapidAssessment of dry eyes and treatmentAssessment of dry eyes and treatment

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