Taking a leave doesn’t have to affect your pension, provided it’s authorized by your employer. When you return from the leave, you can purchase the period to add it to your OMERS credited service. Your employer will provide you with your options and manage the process for you.
The decision to purchase a leave period is up to you. You can use the myOMERS Retirement Income Estimator to weigh the cost of the purchase against how much it will increase your OMERS Plan pension.