I Could See Eight Pleides!

Well, I did it. In September I had LASIK eye surgery. In ten minutes I went from 20/400 to 20/20. Amazing! So many of you have asked about the experience that I thought I would talk about it in this month's column.

I have watched vision correction surgery since the late 70's when a friend of mine had radial keratotomy performed on an experimental basis. I wasn't an amateur astronomer in those days but it still made my skin crawl. It sounded like a huge risk just to avoid wearing glasses or contacts. All those razor edge cuts into the cornea? No thank you.

Vision correction surgery has come a long way since then. But it wasn't until this year that I felt comfortable with the state of the art. Until fairly recently laser surgery involved roughing up the surface of the cornea then "ablating" away corneal material until the new desired curvature is obtained. This procedure, coupled with the less sophisticated laser device itself, meant for slower healing, sometime permanent haloing at night and, most importantly, less accurate "cuts" by the laser than with today's cutting edge technology (literally).

Today the state of the art is "third generation LASIK" which involves more accurate lasers and a simple preparation that almost completely eliminates any disturbance to the corneal surface. Rather than "roughing up" the corneal surface and lasering directly on the surface, the new procedure involved a very thin slicing of the corneal surface which is laid back along a hinge of non-sliced cornea. Think of slicing through a thin layer of an apple but not all the way. Lift up the small slice, take a small bite out of the apple, then lay the cover slice back down in the original position. The laser ablates corneal matter BELOW the critical surface area while the flap is raised. The slice is then repositioned and the tiny thin line of the cut heals quickly. Most people can go back to work in a day or so.

The results for astronomy have been fantastic. Whereas I previously could only detect six of the Pleides, I was able to see eight at the last Explore the Stars program. The ten brightest stars in the Pleiades are under 6th magnitude and are in theory visible to the naked eye. However most amateur astronomers can only see six or seven due to the congestion of stars in the cluster. Next month I am going to work real hard and see if I can pick up number nine and ten.

The biggest worry about laser surgery for the eyes is the phenomenon of haloing around bright lights at night. Prior to having the surgery done I had pictured this phenomenon in my mind as being like a circle of light around a bright object, sort of like the 22.5 degree circle you sometimes see around the Moon when there is ice in the upper atmosphere. After all, that is what a halo should look like, right? A circle of light like the halo on an angel. However that's not it. The "haloing" is more like a circular glow around the bright object, the glow being of equal brightness from the source object to the edge of the glow. Picture M97 the Owl Nebula for a more accurate image of what the glow looks like.

My biggest question about the haloing was whether it occurred on astronomical objects such as bright stars. My suspicion was that it occurred around bright objects like car lights and traffic signals, but might not be a problem around the relative dim light of bright stars. My suspicions were correct. I can see a hint of haloing around bright stars such as Vega and Sirius. But it is slight, and it less apparent than the glare I saw on the same stars if I wore glasses that were even the slightest bit smudged or scratched. There is noticeable haloing around the Moon, but it is not objectionable to me. The haloing around car and traffic lights is there, but it does not bother me. I am told that the haloing effect tends to go away during the healing process in third generation LASIK (although older processes could leave some permanent haloing).

The overall effect of viewing the sky after LASIK is that my eyes have become a magnitude or so more sensitive. I am seeing stars I have never seen before. It's wonderful. And getting rid of the glasses when going back and forth from naked eye to the telescope or binoculars is fantastic.

On the other hand, there is a downside to the procedure for many middle aged amateur astronomers. When you reach your mid-40's your eyes lose their ability to focus on near objects. Thus the need for reading glasses as you get older. However people who are nearsighted get a nifty little perk from nature. Nearsightedness masks the near focus problem. So that middle aged nearsighted people can often go without their glasses all together to read objects up close. Books, instructions, small print on medicine bottles, etc. LASIK takes away your nearsightedness and thus removes the masking effect. So your aging eyes need the reading glasses that you may have avoided before. So LASIK is no guarantee that you will be totally free of the need of reading glasses. There is a technique called monovision that you can ask your optometrist about which would eliminate the need for glasses all together. Basically it involves setting up one eye for close vision and the other eye for far vision. This is not for everyone.

In the October issue of Sky & Telescope Barry Santini (Tele-Vue) wrote a letter to the editor in which he gives advice concerning LASIK for amateur astronomers. I have spoken with Barry several times, both before and after my procedure. His main point the letter is that you want your treated area to be as large are your dark adapted pupil size (7-8 millimeters for most adults). Since the FDA only approves out to 6mm this can be a problem. However, you can go larger than that if the procedure is done on an "experimental" basis. This is NOT as scary as it sounds. The FDA is a very conservative organization and has pegged six millimeters as it current approved range. All procedures beyond that limit are legally called experimental because they don't have that FDA stamp of approval. In my case, my surgeon is one of the few FDA investigators. He gives his approval to new machines and techniques. He has performed more than 12,000 LASIK procedures. My procedure was done based on a seven millimeter dilation (I sat in a completely darkened room for twenty five minutes before my pupil size was measured).

Barry's other big concern is that the person doing the procedure on your eyes have LOTS of experience at it. He indicated 1200 procedures as a good guide. When I told him of the experience of my surgeon (12,000 procedures, FDA investigator, third generation procedure) he felt very confident for me. He wrote the S&T letter, in part, because he wanted people to be sure they got the best care they can and that they should not assume their surgeon knows about the special needs of the amateur astronomer. Do your homework.

One final word of advice: while I went to 20/20 right after the surgery, one week after surgery my eyes were slightly farsighted. I went from a minus 5.0 diopter (moderate nearsighted) to plus 0.75 diopter (slight farsighted). They told me before hand that in the healing process the eyes will tend to come back slightly toward the zero diopter range. That seems to be happening and I have another week before my one month checkup. The goal, of course, would be to be dead on zero diopter. Santini confirms that there is often a drift back toward zero, but that there is not enough track record to state with confidence that this is the definitive pattern. I'll let you know next month what happens.

Bottom line: If I had it to do over again. I would... definitely.

Club News: Our Banquet Speaker, Laurance Doyle of the SETI Institute is a well thought of spokesman for the SETI project and will certainly give us some wonderful insight at our upcoming Annual Banquet. It is our hope to get as many former presidents of the club in attendance for special honors. You won't want to miss it.

The club is moving slowly but surely forward on research and educational plans for the future. Hopefully we can tell you more next month.

Don't miss the October meeting. There will be some fantastic images, videos, and stories concerning the spectacular prominence studded total eclipse from last August.

The goodness of the night upon you
(Othello Act 1 Scene 2)

Russell Sipe