Pterygia Measurements with Standard Slitlamps and with Anterior Segment Optical Coherence Tomography: Pilot

Study

Mark Welch, DO and Steven Waller, MD

No financial interest

Background• Previous Studies Demonstrating Anterior OCT

– Anterior Chamber Dimensions

– Intraocular Lens Position

– Corneal Thickness

– Corneal thinning after Mytomycin C

• Clinical challenges of pterygium measurements

– Subjectivity of Slit Lamp measurements

– Cannot measure thickness with Slit Lamp

Purpose• Compare horizontal measurements of pterygia by

slit lamp beam to caliper measurements overlayed on Anterior Segment OCT images

Methods

• 10 Patients and 13 nasal pterygia were evaluated. Patients with significant ocular surface disease were excluded – Horizontal measurements were taken by two

physicians with the slit lamp beam and caliper at 16 mag

• Measurements were taken from the apex of the lesion to the limbus

– Two images of lesions with Anterior Segment OCT • Caliper measurements of lesions

Methods

• Example of INCORRECT meridian to see lesion – 45 degrees

• Example of CORRECT Meridian at 180 degrees images the lesion

Visante OCT measurements

Caliper Measurements

Difference in Slit Lamp Measurements

0

1

2

3

4

5

1 2 3 4 5 6 7 8 9 10 11 12 13

pterygia

mm Physician A

Physician B

SD = 0.32

MD = 0.30

Results

Results

00.5

11.5

22.5

33.5

4

1 2 3 4 5 6 7 8 9 10 11 12 13

pterygia

mm Image 1

Image 2

SD = 0.12

MD = 0.1

Difference in OCT Measurements

Conclusions• OCT gives statistically more reproducible results

than slit lamp for horizontal measurements of pterygia (P=0.0256)

• OCT can reproduce measurements in the same axis meridian and appears to be less subjective with regard to the starting and stopping point for making measurements

Study Limitations

• Small number of patients

• Inherant variability of slit lamp measurements

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