Mark Welch, DO and Steven Waller, MD No financial interest

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

References1. Buchwald HJ, Muller A, Spraul CW, Lang GK. Ultrasound Biomicroscopy of Conjunctival Lesions. Klin Monatsbl

Augenheilkd. 2003 Jan-Feb; 220(1-2):29-34.2. Buchwald HJ, Muller A, Kampmeier J, Lang GK. Optical Coherence Tomography versus Ultrasound Biomicroscopy of

Conjunctival and Eyelid Lesions. Klin Monatsbl Augenheilkd. 2003 Dec; 220(12):822-9.3. Baikoff G, Lutun E, Ferraz C, and Wei J. Static and Dynamic Analysis of the Anterior Segment With Optical Coherence

Tomography. J Cataract Refract Surg. 2004 Sep; 30(9):1843-50.4. Adamis AP, Starck T, Kenyon KR. The Management of Pterygium. Ophthalmol Clin North Am. 1990; 2(4):611.5. Kent C. Breaking New Ground in Ultrasound. Review of Ophthalmology. 2006 Nov; 13(11):22-26.6. Lin, H, Shen S, Huang S, Tsai R. Ultrasound Biomicroscopy in Pigmented Conjunctival Cystic Nevi. Cornea. 2004 Jan;

23(1):97-99.7. Solomon A, Kaiserman I, Raiskup F, Landau D, Frucht-Pery J. Long-term Effects of Mitomycin C in Pterygium Surgery on

Scleral Thickness and the Conjunctival Epithelium. Ophthalmology. 2004 Aug; 111(8):1522-1527.8. Dada T, Sihota R, Gadia R, Aggarwal A, Mandal S, Gupta V. Comparison of Anterior Segment Optical Coherence

Tomography and Ultrasound Biomicroscopy for Assessment of the Anterior Segment. J Cataract Refract Surg. 2007 May; 33:837-840.

9. Emmy YM, Mohamed S, Leung C, Rao S, Cheng A, Cheung C, Lam D. Agreement Among 3 Methods to Measure Corneal Thickness: Ultrasound Pachymetry, Orbscan II, and Visante Anterior Segment Optical Coherence Tomography. Opthalmology. 2007 October; 114(10):1842-1847.

10. Fujimoto JG. Optical Coherence Tomography: Introduction. In: Bouma BE, Tearney GJ, eds, Handbook of Optical Coherence Tomography. New York, NY, Marcel Dekker, 2002; 1-40.

11. Goldsmith J, Li Y, Regina M, Chalita MR, Westphal V, Patil C, Rollins AM, Izatt JA, Huang D. Anterior Chamber Width Measurement by High-Speed Optical Coherence Tomography. Ophthalmology. 2005 Feb; 112(2):238-244.

12. Lin A, Stern G. Correlation between pterygium size and induced corneal astigmatism. Cornea. 17:1998; 28-30.13. Payman A, Mohammed-Salih, Ahmad F, Sharif . Analysis of Pterygium Size and Induced . Corneal Astigmatism.

Cornea. 27: 2008; 434-438.