First get your blood pressure checked standing and sitting position.. If significant difference is there you might have postural hypotension. Other possibility could be anxiety which episodically causes sudden blackout, burning sensation, difficulty to focus. Please consult and provide more details for accurate diagnosis.

This condition might indicate orthostatic hypotension which is unlikely to happen in your age.. Given that you haven't mentioned about any comorbidities any history of drug intake or any familial disorder ,it is difficult to reach to any provisional or differential diagnosis. So it is better that you should consult an ophthalmologist and a neurologist at the earliest

With such serious symptoms it is better to consult a Neurophysician and an Eye Specialist in your area.

orthostatic hypotension

Yes you are suffering from postural hypotension which needs to be evaluated and treated

Can help you, kindly consult and provide detailed history for proper diagnosis and further management

Need to know more detailed history and clinical examination for further evaluation and management Kindly consult 😊🙏

Need few more details Kindly consult

Check your BP Drink lots of water and ORS Or consult