65 now and noticing the older I get the more light I need to read or do mechanical work etc. I can’t figure out if it is because things are just not as clear or if I am actually not taking in as much light. If I slip on reading glasses it does help but I still seem to need considerably more light than I did at 25.
Indeed, “letting less light in” is a good way to put it.
At least two things may be contributing (and likely more):
-
Cataracts - the lens gets cloudy as we age so less light gets through to travel on to the back of the eye (retina)
-
The pupils in us older folks tends to be relatively constricted, i.e. less light gets in
Worth seeing an ophthalmologist.
I think the light is the same, but the receptor cells in the eyes age and are less effective.
I am not a doctor. This is not a diagnosis. This is not medical advice.
There. Got that out of the way.
What you’re describing sounds precisely like what both of my parents described in recent years before getting a diagnosis of cataracts. Both have had surgical removal and replacement with artificial intraocular lenses to good effect.
That may not be what you are experiencing. But it was what my folks experienced.
See an eye doctor.
I rememeber as a young mechanic the older mechanics were always walking over and shoving a drop light down into my work when I could see fine. Now I find myself tempted to go over and shove a drop light down into the work of the younger mechanics because I cannot imagine how they can see. But I know better so resist the urge.
I did get checked for cataracts and no problem there. My vision has remained at 20/40 for all of my adult life. I do wear glasses for night driving and have noticed a difference here also. I used to slip on my glasses at 65 mph and above at night, now I find myself reaching for them at 55 mph and if it is real dark night I just wear them all the time regardles of speed.
I understand that up to the age of about twenty-five, give or take, one’s pupils can dilate to about 7mm maximum, in dark conditions. After than, you lose about 1 mm of dilation every ten years or so, down to about 4mm.
I only know this because I bought some binoculars recently and that was the advice - that having an “exit pupil” greater than 5mm or so is probably pointless if you’re over 40.
You may not have cataracts bad enough to require treatment, but I’ll guarantee that your 65 year old lenses do not let as much light through as they did when you were younger. All lenses age, and transmit less light. Only some of them get so bad that they qualify to be diagnosed as cataracts, and not all cataracts are bad enough to need intervention.
That makes good sense. I feel like my eyes are pretty normal compared to others of my age.
I just have a slightly higher wattage bulb in my reading lamp now and find myself reaching for lights more often than in my youth.
Oh, yeah, I most definitely notice that, even though I have had cataracts removed from both eyes a few years ago. That is the reason I, and so many other geezers stop driving at night.
At 86 (well, I will be next month), with glasses I can see quite well on bright days, but if it gets too cloudy, I begin to have a bit more trouble reading traffic and street signs. Fortunately, in AZ almost all days a very bright.
Likewise, reading small type in a newspaper is very easy in bright light, but in the evening, even with a good lamp, I often resort to a magnifying glass.
But, hey, how many pieces of equipment or machines could work all day, every day, for 86 years and still function as well. My eyes are only two of the many parts that are wearing out. The only parts of my body that don’t hurt, are numb. 
I’m 67, and have had cataract surgery in one eye. When I switch back-and-forth between the eyes, the eye that had the surgery is actually a little dimmer. I can’t explain that.
But yeah, I have to use a magnifier for things that I could see clearly just a couple of years ago. And one by one, all my ceiling lights are just bare bulbs. This screws up my domestic feng shui.
I was told by my doctor that I have a condition called “hooding” where my eyebrows drop down in front of my eyes, limiting my vision. The operation to correct this is called Blepharoplasty. I haven’t corrected it because it does not bother me that much, but it does occasionally cause me problems in low light situations.
I had bilateral cataract surgeries a couple of years ago, and my vision is the same. In fact, I wear the same bifocals that were prescribed for me years before the surgeries. I still have the same difficulty reading in dim light. My ophthalmologist did the cataract replacements so I would need no glasses at all - so he said. (One eye with intraocular lens designed for near and one for far.) Did not work out that way. You no longer need wait for the cataracts to “ripen.” The surgery can be done now at any time because FDA has allowed such surgery for visual improvement now, which previously was not allowed.
The problem with intraocular lenses is that they do not adjust, such as natural lenses do.
I think the retina itself becomes less sensitive with age. I recall something from the FAA illustrating how one’s night vision drops off with age, such that by the time you’re 60 or 70 a night with a full moon looks as dark as a moonless night did when you were 20.
Add catarats on top of that and yeah, you need more light.
The main thing I noticed as my cataracts developed, was the dazzle effect. Driving at night became almost impossible because oncoming headlights completely blinded me.
After having both eyes done, I now only wear cheap magnifying glasses for reading and computer work. By cheap I mean £3.00 from a supermarket.
Yeah, that is something I was asked. But I’ve been seeing halos since my RK surgery in 1991.
I started to notice this when I got into my late 40s, that it was harder to focus in dimmer light. My wife who is 12 years younger than me doesn’t understand why I want the lights on all the time.
That’s what I was about to say… it’s not so much that older folks have more constricted eyes, but rather that they don’t dilate so much in low-light situations.
That’s interesting, but not quite true in my case. My night vision has always been pretty good, but now not enough to drive at night (I also get the halo effect).
However, after about 15 minutes in the dark, my vision is still pretty good. Back when I was 75, some of us climbed the local mountain under the full moon, something I had always wanted to do.
I brought a flashlight, but from the beginning I found I did not need it. It was almost like daylight, in fact so bright, the cacti cast shadows.
I can still take walks at night (much cooler here in the AZ desert), and if there is any phase of the moon out, I have no trouble seeing almost everything.
This is kind of weird, as in daylight my vision has deteriorated to the point that I have to wear glasses with almost the maximum amount of correction.
I have to be glad something still works. 
I believe the primary thing going on is the older lens becomes out of shape. When a greater amount of light enters the eye the muscles tighten up and bring it to a better shape to form a sharp image.
There are a few things going on as the eye ages. The index of refraction goes down and the eye bulges more and becomes thicker. These things contradict each other for a while and give us good vision, but eventually bad vision wins out.
I think this small pdf supports my memory of the subject.