Vol. 6, Issue 4 (2017)

Author(s):
Rajyeshwanth and Venkateswar Ravisankar

Abstract:
Background and Objective: Glaucoma is a progressive optic neuropathy often necessitating surgical intervention to control intraocular pressure (IOP). However, ocular surgeries, particularly trabeculectomy or glaucoma drainage implant procedures, can induce changes in corneal curvature, resulting in astigmatism. The objective of this study was to evaluate the effects of glaucoma surgery on corneal astigmatism and to compare pre-operative and post-operative astigmatic changes in patients undergoing surgical treatment for glaucoma.

Material and Methods: A prospective observational study was conducted on 40 patients diagnosed with primary open-angle glaucoma scheduled for trabeculectomy or glaucoma drainage device implantation. This study was conducted at the department of Ophthalmology, Madha Medical College, Kundrathur Main Road, Kovur, Chennai, Tamil Nadu, India from February 2016 to January 2017. Corneal astigmatism was measured using automated keratometry and corneal topography pre-operatively and at 1 week, 1 month, and 3 months post-operatively. The magnitude and axis of astigmatism were recorded and analyzed statistically to assess changes over time. Patients with previous ocular surgery, corneal pathology, or irregular astigmatism were excluded.

Results: Pre-operative mean corneal astigmatism was 1.20 ± 0.40 D. At 1 week post-operatively, mean astigmatism significantly increased to 2.10 ± 0.55 D (p<0.001), with a With-The-Rule (WTR) shift observed in 62.5% of cases. By 1 month, astigmatism began to decrease, averaging 1.65 ± 0.50 D, and at 3 months, it stabilized at 1.35 ± 0.45 D, showing no significant difference from the pre-operative values (p>0.05). Axis changes were noted predominantly in WTR direction in early post-operative period, gradually returning toward baseline by 3 months.

Conclusion: Glaucoma surgery temporarily increases corneal astigmatism, especially in the early post-operative period, with a predominant WTR shift. However, most astigmatic changes tend to stabilize or return toward baseline within 3 months. Monitoring and managing these changes is essential for optimizing post-operative visual outcomes and patient satisfaction.