Hi MegumiEto
I had this very recently with my 2 year old DD. Her right pupil showed up white or yellowish in a number of photos. I remembered that that could be a sign of something, so I googled it and saw image after image of children with similar-looking photographs, many of whom had been diagnosed with retinoblastoma. Terrifying.
While I know that it's very anxiety-producing, I think it's great that your GP and the specialist are taking your concerns seriously and getting him seen to right away. In our case we had to actually educate the GP on why a white-eye photo is cause for concern, and basically plead for a referral to a pediatric opthamologist. We did get one, but it was for a date two months away so we called the opthamologist's office directly and got in right away when we explained what the issue was.
When we went in, the opthamologist took one look at the picture and said "yes, that's quite concerning" and like you and WidowWadman, I was scared to death. She said that she was looking for three things: a cataract, Coate's disease, and Retinoblastoma. First she put drops in DD's eyes to dilate her pupils, and we were sent to the waiting room for about twenty minutes. DD didn't seem at all bothered by the drops and played happily in the waiting room. Then we were called back in, and the doctor asked me to hold DD's arms and legs while DH held her head still. The doctor then put these clip things on her eyelids to hold them open, and shone a very bright light into her eyes, looking at both retinas.
I'll be honest and say that the exam was not at all pleasant; DD struggled and screamed bloody murder and hated every second of it, but it only took about five minutes or maybe less, and as soon as it was over she was absolutely fine again. Also, she's a big strapping toddler so your little DS might not fight it as much which may make it easier on you and him both.
In our case, the opthamologist was able to rule out Retinoblastoma and the other two diseases. She noted that the worrying pictures had been taken on a camera phone with an LED flash, and asked whether we'd noticed anything like this when using a regular camera. We haven't, so the likelihood seems to be that the camera phone flash just bounces off the eye in a funny way and produces the white-eye effect. After our visit I looked up 'white eye' on some photography websites and found that it's a problem that photographers have when they are working with LED flashes. Was your dodgy picture taken on a camera phone by any chance?
After DD's eyes got a clean bill of health, DH took her to the bathroom to change her diaper and I went out into the car and sobbed my heart out, mostly for relief, but also for my dear friend whose little boy is fighting cancer (leukemia), and for the general fragility of life and the awful knowledge that I can't possibly protect DD from all eventualities. So I understand the terrible anxiety you must be feeling right now, and I know that the only thing that will make it go away is your specialist telling you on Monday that DS is just fine.
Please try to remember that it's entirely probable that by Monday evening you'll be another relieved mother with a reassuring story to tell the next person who spots white eye in their child's photograph. Also try to remember that even in the UNLIKELY worst case scenario (that it is, in fact, retinoblastoma), this is a very treatable form of cancer with a very very high cure rate in the developed world. I don't mean to minimise it in any way at all, but when I was waiting for our appointment I found that to be a useful thing to remember.
I'll be thinking of you and will hope to see a positive update after your appointment. All the best of luck x