tonight. >> i immediately thought that something was wrong with her eyes. >> the little girl whose world was fading into darkness. >> please fix my eyes. >> the young woman with dreams of seeing the stars. the rare disease. stealing their sight. >> look at mama. >> she can't see. >> our bob woodruff with the incredible medical break through, giving hope. and a vision for the future. >> i can see the stars! >> this special edition of "nightline," miracle of sight will be right back.

♪ ♪ ♪ ♪ ♪ ♪ ♪ ♪

"nightline," miracle of sight continues. here now, bob woodruff. >> other than the sun, i've never seen a star, ever. >> reporter: imagine a world without starlight. >> i've been told all my life, my vision is going to go. it's happening. and i get really scared. >> reporter: a world without detail. >> i couldn't really see the castle because it was so dark.

>> i immediately thought that something was wrong with her eyes. knowing that both my husband and i gave her a mutated gene. >> reporter: tonight, two incredible journeys. >> jesus, please fix my eyes. amen. >> reporter: one revolutionary new drug. >> this was an eureka moment. just knock your socks off. >> reporter: and a race against te time to stop the world from going dark. >> if i had the chance to save her vision, sign me up. >> i can't believe it's finally happening. ♪ happy birthday to you >> reporter: 6-year-old monroe lee dreams like many other girls, in visions of pink and princesses, but monroe isn't like most little girls, because her dreams just don't match her

reality. >> i couldn't really see in the dark. >> reporter: does she explain this to her friends? what does she say? >> monroe can't see in the dark. >> reporter: she suffers from a rare genetic disease that means she will eventually go blind, for a child who loves horse racing. >> he won! he won, yes! >> reporter: and disney. everything disney. that means never experiencing the glowing wonder of cinderella's castle at night. >> i couldn't really see the castle because it was so dark. >> hi, pretty girl. >> reporter: monroe's mom says she noticed immediately that something was wrong when monroe was just a baby. and it got worse. monroe kept missing key milestones. so at 18 months she's still not walking. >> she did this scoot jump like crawl. >> reporter: it wasn't until she was 3 years old that three learned her diagnosis, a genetic mutation inherited from her

parents. only about 2,000 people in the whole country have it. >> it was scary. it was scary. i mean, knowing that both my husband and i gave her a mutated gene. >> reporter: but there's an extremely rare condition. >> we both blamed ourselves for a long time. >> reporter: while her family has given her the best childhood possible, they know time is precious. >> if monroe wanted to do it, we did it, because tomorrow wasn't promised. i didn't know if i'd wake up one day and she wouldn't be able to see at all. >> look at mama. >> monroe, she can't see. >> reporter: heather is going through the same thing. >> people always say they can't tell i'm blind. and i think that comes down to me being used to it and not

letting me stop me from anything. >> reporter: for the 25-year-old, life is one big blur. as a child, she was diagnosed with the same genetic disease that monroe has. >> it goes by lca. i've been told all my life my vision's going to go. it's happening, and i get really scared. i try not to think about it. >> reporter: the main issue with lca is light sensitivity. heather can't see anything at night, a tough thing for someone who wants to be an astro physicist and study the stars. you have no idea what they look like. >> i've only seen them in pictures, that's it. >> reporter: even on the brightest day, heather sees just a fraction of what other people do, using her guide dog luna to get around. >> i can see the trees where they're at as blobs, things that are tall, and i can tell them different from the buildings. >> reporter: shadows and shade are a constant enemy. >> i've tripped a few times and

have a mini heart attack when you trip going downstairs. >> reporter: so are faces which makes it hard for her to recognize her friends. >> there's been times i didn't know it was her, so i might make a little comment to say something. you didn't know that, did you? >> no, i never noticed that. >> when she was smiling, i could tell, but i see where her eyes are, but i can't see her eyes. >> reporter: heather uses a variety of tools. high tech. >> i have to invert for writing. >> reporter: and low tech. >> my felt tip marker. my recipe's on my ipad so i can see it better. >> reporter: but her biggest, her fiance, christian. >> i've tried to look at him super close in the sun. never really seen him, never been able to see a blemish or anything like that on his face. >> she always looks for the best in things. i want to be with her knowing that she's like that. >> i'm scared to not be able to

see like christian's face or our future children's faces. i wanted to be a mother all my life. so i want to be able to at least see their faces. >> reporter: she was giving up hope when suddenly, she got a call. how did you get the word? >> i was asleep one morning and my dad called me. you awake? there's a thing on the tv, a cure for the blind, check it out. i think it's your disease. >> reporter: it all started in this medical lab in philadelphia with a groundbreaking new drug. for almost as long as they've been married, doctors jean bennett and albert mcguire, an eye surgeon, have been searching for a cure for genetic blindness. >> at that point in time the technology did not exist. >> reporter: so if you were older, mothre experienced in th you would have known it was almost impossible. >> it's a good thing not knowing, because it would have been daunting. this is ridiculous. >> reporter: eventually, technology caught up.

dr. bennett figured out a way to replace the gene that cause people like heather and monroe to go blind. rpe 65. and dr. mcguire figured out how to inject the replacement into the patient's eye. the treatment now call called luxturna. >> then the next thing, wouldn't it be great if we could make blind children see? >> reporter: heather quickly signed up. dr. aaron miguel will handle both surgeries. >> it is changing the course of the disease in a way we never saw before. >> reporter: while both operations will be the same, results will be unique, age is a big factor. >> monroe who is 5 may have more improvement and stable improvements over the long term, compared to heather because of age may have lost more tissue. >> reporter: making the decision to risk what eyesight they have

left is a big deal. enter christian gardino. ♪ ♪ when i had you >> reporter: millions fell in love with him on season 12 of america's got talent, where he earned the coveted golden buzzer. when he was 12, christian was chosen for dr. bennett and dr. mcguire's clinical trial. was this a tough call? >> no. >> reporter: what's the very first thing that you saw? >> i think it was my parents. seeing my parents' face in detail, that was pretty incredible. >> reporter: before surgery, doctors recorded christian trying to navigate a maze. you can see he has trouble staying in line, missing steps and running into barriers. after treatment, christian saw things he'd never seen before, maneuvering around the obstacles, flawlessly. >> massive, massive improvement, yeah. i'd take anything of what i have

now over what i had before. >> reporter: after months of waiting, it's heather's chance to gain something she's always wanted. >> my hopes that i'm afraid to admit. to see a star and to be able to see christian's face, actually see his eye color. >> i have a appointment at the vision center. >> reporter: it will take two operations. her left eye is up first. heather's dad and step mom arrive. >> it's still hard. oh, boy. my vision doesn't define who i am, but it's kind of made me who i am. i don't know how to not be the blind girl. >> reporter: the operation itself will last about an hour.

>> the luxturna goes underneath the retina. we use a very fine needle to deliver a small amount of this medicine underneath the retina. the retsna is only a quarter of a millimeter thick. no room for error. even a small tremor can make a difference. >> reporter: dr. miguel threads that delicate needle and heather's father and fiance wait. >> i love you, baby. can i have a kiss good-bye? i'll see you when you wake up, okay? >> reporter: for monroe, the surgery could be a chance at a normal childhood. >> she was afraid. she didn't know what to expect, but i do know she was scared. just to see my baby willed back, praying that i'm making the right decision. praying that the end result is going to be what we hope it will be. >> reporter: post surgery, they both have to wear a protective eye patch for 24 hours, and then that first moment of truth. once she took that patch off of her eye, what did she see?

>> nothing. >> reporter: black? >> yeah, it was black. she kept saying i couldn't see, i can't see. >> we're going to check your vision. >> i'm scared to open it. >> you see my hand moving here? >> reporter: stay with us. there was no hesitation, i went straight to ctca. after my mastectomy, it was maddening because i felt part of my identity was being taken away. when you're able to restore what cancer's taken away, you see that transformation firsthand knowing that she had options that she could choose, helped restore hope. my team made me feel like a whole person again. cancer treatment centers of america. appointments available now. cancer treatment centers of america. stop struggling to clean tough messes with sprays. try new clean freak! it has three times the cleaning power to dissolve kitchen grease on contact. it works great on bathtubs. and even stainless steel. try new clean freak from mr. clean.

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"nightline," miracle of sight continues. here again, bob woodruff. >> reporter: heather is scared. over the course of the next few days her life is going to change forever. for better or for worse. >> it was the longest night ever. >> reporter: the 25-year-old is recovering from surgery, to see

if the first-everybody approved live gene therapy can restore her eyesight. >> now we're going to check your vision. >> i was really nervous when we took the patch off that day. it's just really scary. and when i couldn't see the nurse's hand going back and forth, i kind of panicked. >> do you see my hand moving here? >> no. >> did i really try to fix my eyes and make them worse now? >> hey, heather. >> is this backfiring? >> so let me have a look. >> very blurry. >> very blurry. look straight. up and left here. >> oh, that hurts. >> excellent. looks perfect. all the medicine's absorbed. okay. you do have an air bubble. >> and that's what causes the blurriness? >> yes. the optics of the air is very poor, that's why it's so blurry. >> reporter: dr. miguel is not alarmed. he says the air bubble is normal

and the day after surgery is always rough. but by the end of that first week she was reconsidering whether to have the second operation at all. to fix her other eye. >> i still can't see the same as before surgery, like my vision is still worse. >> reporter: but she decided it was worth the risk. >> leather, this. is dr. miguel. i know you're just warking up. everything looks so perfect, all right? just like the other eye. we'll let you relax and i'll see you tomorrow morning. okay. great. >> reporter: nearly all the major improvements will happen in the first month after both surgeries. >> he likes it! >> reporter: and monroe's progress has been incredible. >> i can see the stars! >> what, baby? >>ki see ti can see the stars!

>> reporter: after surgery, i imagine it's pretty shocking. >> she's a whole new girl. >> reporter: born again? >> born again. >> reporter: does she realize it? >> oh, 100%. >> what do you see? >> stars in the sky! >> reporter: the treatment, opening up a whole new world for the little girl, a world she'd never seen before. >> where do you want to go? okay, show me the way, babe. which one is your favorite princess? >> um, belle. >> yes, come on. >> reporter: in fact, on this day, monroe has gone to transform into a princess.[ appu ase forhe 6-year-old princessess ride. those are different. >> those are always the same, honey. you just couldn't see them

before. everything was worth it. my baby could see. >> reporter: every minute, every dollar? >> everything. >> reporter: all worth it? >> 100%. >> reporter: almost two months after surgery, heather was still struggling to really see the impacts. >> the recovery process is much harder for me than i expected. my peripheral has improved a lot. >> reporter: what can you see right now? we decided to test out heather's eyes in the dark. one of her dreams was to walk on the beach at night. can you turn off the light completely? >> just give my eyes a second. just let them adjust a little. i see that light, it looks like it's glowing almost, like there's reflection on the bottom? what's over this way? i'm not sure if there's something. >> reporter: those are two white lines of the waves. >> holy moly. i see those a lot.

i see a glare. is that from the moon? >> reporter: yes. >> this is crazy. oh, i hear the water coming. >> reporter: back up a little bit. can you see it right there below us? >> i do, it's like right that. i do see that. and there's a little second one coming. >> reporter: yes, exactly. that's awesome. is one of your dreams to see the stars? >> oh, yes, definitely. it's always been a dream of mine. just kind of waiting because i'm afraid i won't be able to. >> reporter: now she will get that chance. >> so i set up two telescopes. >> reporter: thanks to amateur astronomer john isaacs who set up some telescopes for us. he decides to start with the moon. if heather can't see something that large through a scope she will never be able to see a star. >> oh, i see it. the defined shape. it's amazing. >> reporter: now the real moment of truth. john repositions to look at

sirius. the brightest star in the sky. if you have 20/20 vision you clearly see the star here in our video with the naked eye. for heather, her only hope is through this telescope, after 25 years of waiting. >> so are you seeing it yet? >> find gray spot again. oh, i see it! >> you do? >> are you okay? >> yeah. i see i wacan't even talk. it doesn't seem real. i can't believe i'm seeing a star for the first time ever. oh, my god. it's amazing. >> okay. >> thank you. >> yeah. >> reporter: we'll be right back. what about him? let's do it. [ sniffing ]

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