Despite what your parents might have told you (or what you might have told your own children) there is no law against driving with the interior light on. However, it is important that any interior lighting does not cause any distraction to the driver or other road users and if you were to be involved in an accident it could be considered as a factor in a charge of careless driving.

There is some logic to the suggestion however. When driving a night a car's interior is typically quite dim, so the driver's pupils will adjust to the low light levels. The sudden burst of bright light from an oncoming vehicle can then cause dazzle, so having a higher ambient light level could offset some of this sudden change. You may wish to experiment with using different combinations of interior lights or even reducing their brightness by partially covering them with tape or different specification bulbs. You may also wish to consider obtaining a letter from the eye specialist outlining their suggestion which can be kept in the vehicle in case of any interaction with the police.