Corneal Hysteresis Is Correlated with Reduction in Axial Length After Trabeculectomy

Abstract

Background: We sought to determine whether corneal biomechanical parameters are predictive of reduction in axial length after anti-metabolite trabeculectomy.

Methods: Chinese subjects undergoing trabeculectomy with mitomycin C by a single experienced surgeon underwent the following measurements: Corneal hysteresis (CH, Ocular Response Analyzer, Reichert Ophthalmic Instruments), Goldmann intra-ocular pressure (IOP), central corneal thickness (CCT) and axial length (AL, IOLMaster, Carl Zeiss Meditec, Dublin, CA) were measured pre-operatively, and AL, CH and IOP were measured 1 day and 1 week post-operatively.

Results: Mean age of 31 subjects was 52.0 ± 15.2 years, and 15 (48.4%) were female. The mean pre-operative IOP of 21.4 ± 9.3 mmHg was reduced to 8.2 ± 4.6 mmHg 1 day and 11.0 ± 4.4 mmHg 1 week post-operatively (p < 0.001). AL declined from 22.99 ± 0.90 to 22.76 ± 0.87 mm at 1 day and 22.74 ± 0.9 mm at 1 week; 30/31 (%) eyes had a decline in AL (p < 0.001, sign test). In multivariate linear regression models including post-operative data from 1 day and 1 week, greater decline in Goldmann IOP (p < 0.0001, greater pre-op axial length (p < 0.001) and lower pre-operative CH (p = 0.03), were all associated with greater decline in post-operative axial length.

Conclusions: Eyes with lesser ability of the ocular coat to absorb energy (lower CH) had significantly greater decrease in axial length after trabeculectomy-induced IOP-lowering.

KEYWORDS::

• Corneal hysteresis
• Central corneal thickness
• Glaucoma
• Eye wall
• Trabeculectomy
• Axial length
• Corneal resistance factor
• Corneal biomechanics
• Ocular response analyzer

ACKNOWLEDGMENTS

Previously presented at the APAO meeting, Bali, Indonesia May 2009.

Declaration of interest: Funding provided by the Joint Shantou International Eye Center and the Chinese University of Hong Kong. The Ocular Response Analyzer utilized in this study was loaned free of charge by Reichert Ophthalmic Instruments; Dr. Congdon has received travel support from Reichert Ophthalmic Instruments.