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Abstract #5976 Published in IGR 2-2
Effect of corneal thickness on the accuracy of intraocular pressure measurement in rabbits after excimer laser photoablation
Stahl J; Vold SJournal of Cataract and Refractive Surgery 2000; 26: 736-743
PURPOSE: To determine whether intraocular pressure (IOP) measurements using pneumotonometry and Tono-Pen tonometry are accurate after excimer laser photoablation of the central cornea in rabbits. SETTING: Department of Ophthalmology, Scott & White Hospital, Texas A & M Univer sity College of Medicine, Temple, TX. METHODS: Ten rabbits had excimer laser phototherapeutic keratectomy (PTK) in the right eye to thin the central corneal thickness (CCT) by approximately 20%. The left eye served as the control. The diameter of each PTK was 6.0 mm. Four weeks later, the rabbits were examined under general anesthesia. The eyes were cannulated, and IOP was maintained at 10, 20, and 30 mmHg and measured using an IOP transducer, Tono-Pen, and pneumotonometer at each pressure level. The readings were compared. RESULTS: One rabbit was excluded from the study because of recurrent erosions and corneal edema. There was no statistically significant difference in measurement error between the operated eye and control eye for the Tono-Pen (p = 0.12) or pneumotonometer (p = 0.35). There were significant differences in measurement error as pressure increased for the Tono-Pen (p < 0.01) and pneumotonometer (p < 0.01). The increase in measurement error with the increase in pressure was similar in the two eyes: Tono-Pen (p = 0.96) and pneumotonometer (p = 0.55). A paired t test showed the observed CCT was comparable (p = 0.79) in the pre-laser right eyes (mean 400.56 μm ± 11.29 (SD)) and control eyes (mean 401.78 ± 19.78 μm). CONCLUSION: Photoablation of approximately 20% of the CCT in rabbits by excimer laser PTK did not significantly alter the accuracy of IOP measurements by the Tono-Pen or pneumotonometer.
Dr. J. Stahl, Department of Ophthalmology, Scott & White Memorial Hospital and Clinic, Texas A & M University System Health Science Center, College of Medicine, Temple TX 76508, USA. drjstahl@hotmail.com
Classification:
2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
