In subordinate clauses introduced by dass or wenn, the finite verb moves to the end of the clause. For example with dass:
Ich weiß, dass der Student ohne seine Brille die kleine Schrift kaum lesen kann.
Here kann closes the subordinate clause.
With wenn you could say:
Wenn der Student ohne seine Brille ist, kann er die kleine Schrift kaum lesen.
Notes: In the wenn-clause, ist goes to the end; kann remains in second position of the main clause.
kaum means “hardly” or “barely,” implying he can do it but with great difficulty. If you use nicht, you simply negate the ability:
Ohne seine Brille kann der Student die kleine Schrift nicht lesen.
This means “he can’t read it at all,” which is stronger than “he can hardly read it.”
You can form an infinitive clause with zu to express “without doing something.” For example:
Ohne seine Brille aufzusetzen, kann der Student die kleine Schrift kaum lesen.
The structure ohne + [NP] + zu + Infinitiv acts as your introductory phrase. The finite verb kann still occupies the second position, and the main infinitive lesen remains at the end.