Prospective Study On Corneal Refractive Changes After Vitrectomy

Purpose: Prospectively study on comeal refractive changes after vitrectomy with Orbscan II comeal topographic system.Materials and Methods:1. Case choices: 25 cases with vitrectomy and silicone oil or gas injection were observed. All cases without comeal disease or lens opacity.2. Observation items: comeal refractive power, astigmatic power, and astigmatic axial in 3.00mm and 5.00mm areas of comeal anterior surface and posterior surface were observed.3. Examinations time: pre-operation, one week, one month, and three months after operation.4. Statistical analysis: we deal with comeal power, astigmatic power and astigmatic axial of anterior surface between pre-operation and 1week, 1month, 3months after surgery with paired samples T-test, the same as the posterior surface.Results:1. Changes of comeal refractive power: the comeal refractive power at 3mm and 5mm areas of anterior and posterior surface between pre-operation and 1 week, 1 month, 3 months after surgery did not significantly change(P>0.05).2. Changes of comeal astigmatic power: the astigmatic power at 3mm and 5mm area of anterior and posterior surface significantly changed (P<0.05) between pre-operation and 1 week after surgery, and did not significantly change (P>0.05) at 1 month and 3 months after surgery.3.Changes of corneal astigmatic axial: except the astigmatic axial at anterior 5mm and posterior 5mm area significantly changed (P<0.05) between pre-operation and 1 week after surgery, the astigmatic axial at 3mm and 5mm areas of anterior and posterior surface did not significantly change (P>0.05) between pre-operation and after surgery.Conclusion:1. The vitrectomy affects corneal mean refractive power of anterior and posterior optical zone minimally.2. The vitrectomy affects corneal astigmatic power obviously at early stage of post-operation, and the increase of posterior corneal astigmatic power is more than that of anterior. The astigmatic power recover to the pre-operation status at 3 months.3. The vitrectomy affects corneal astigmatic axial obviously at early stage of post-operation, and the change of anterior corneal astigmatic axial is similar to that of posterior, both of them drift to the meridian of vitrectomy incision. The astigmatic axial recover to the pre-operation status at 3 months.