THIS IS A DETAILED IN-DEPTH ARTICLE ON THE MOST FREQUENTLY ASKED QUESTIONS ON LASIK SURGERY (SPECTACLE REMOVAL SURGERY) WHICH TRIES TO CLEAR ALL THE COMMON DOUBTS IN SIMPLE & EASY TO UNDERSTAND LANGUAGE.
SPEND A FEW MINUTES AND READ IT PATIENTLY & THOROUGHLY TILL THE END TO CLARIFY ALL THE MISCONCEPTIONS REGARDING THE LASER SURGERY OF EYES FOR GLASSES REMOVAL.
Q1. What are A / C / E / I / K / O / Q / Z - Lasik.. so on & so forth? Are they all same? Which one is the best for me?
The Thickness of our CORNEA is around 550 microns (0.55mm) on an average and it normally varies between 535-570 microns.
And the Cornea is never a perfectly spherical structure. Its shape is slightly different. It is rather sort of an “Asphere”. Asphericity and Ocular Aberrations (optical & refractive system defects) may be described and measured in many-many forms (one of them is "Q" value), details of which is beyond the scope of this article and most patients DO NOT NEED to worry about any of it.
We try to maintain the Asphericity of cornea & optical system of the eye in maximum possible way during any surgery, whether we do Cataract-Phaco surgery (by putting an aspheric lens implant) or Lasik (by creating and Aspheric Ablation shape with Blend Zone).
The higher the refractive error from 1.75-2 dioptre you have in your eye, the more are chances of disturbing the "asphericity" of cornea if we do just a simple plain "Spherical profile" ablasion in Lasik. So it is better to go for "ASPHERIC" profile Lasik, if you have number more than 2.0 dioptres. (Actually Aspheric Lasik is recommend in Every case regardless of how small the number is.)
"C"USTOM or WAVEFRONT-"GUIDED" Lasik (also known as “C-Lasik”) is actually needed in less than 5-10% cases where you have significant "HIGHER ORDER ABERATIONS" or "HOAs" detected on an ABBEROMETER matchine. These HIGHER ORDER ABERATIONS are some special defects of Refraction which can arise either from the corneal SURFACE itself (TOPOGRAPHY related - which treatments like CONTOURA correct) or from WITHIN the eyeball (WAVEFRONT related which treatments like ZYOPTICS / CUSTOMVUE etc correct).
These abberations CANNOT be corrected by your glasses (spectacles can correct only spherical or cylindrical number). These HOAs are sometimes responsible for the slight blurring of vision of the last lines in the vision chart despite seeing from your best corrected glasses.
Many different Companies have their own different Topography-Aberrometry machines and have named each of their own LASIK PROCEDURE platforms with some sort of "prefix" names (eg ZEE-Lasik or Zyoptics is the C-Lasik of BAUSCH n LOMB-Technolas Platform, Topography guided T-CAT by WAVELIGHT Allegro (ALCON-Contoura Vision treatment), C-Lasik of AMO-'C'USTOM-VUE, Nidek-NAVEX with OPD-Scan, CRS Master-MEL 80/90 by Carl ZEISS, Schwind-ESIRIS /AMARIS so on n so forth).
Patients might not feel much difference in Wavefront guided / Topography guided-Custom treatments & Aspheric Treatments unless there are significant HIGHER ORDER aberrations in your eye (which is only rarely a case).
So just an "ASPHERIC profile Lasik" (also sometimes called as WAVEFRONT-"O"PTIMIZED Lasik) is ALL what is ACTUALLY required in MOST CASES for a decently clear vision without glasses (to reduce majority of the confusion). (But If there are a significant amount of higher order aberrations in your eye, then Ocular Wavefront-guided or TOPOGRAPHY-guided Customized treatment can give you a better, crisper and sharper vision than Aspheric-Lasik as all Custom procedures are more centred on the visual axis.)
A technical point to be noted here is that any sort of "CUSTOM" treatment will require additional corneal tissue (PER DIOPTRE reduction of number) to be ablated as compared to a non custom procedure . So while non-custom and aspheric treatments may be streched upto say 8-9 dioptres (or rarely even slightly more than that) , the custom treatments of any sort can be safely streched only upto 6-6.5 dioptres (for the same amount of corneal thickness given for aspheric treatments) mostly and only rarely beyond that as the Lasik procedure then itself will cause formation of certain INDUCED ABBERATIONS if treatment stretched beyond recommended levels.
Q2. What is Blade-Free Lasik / Femto-Lasik ?
The ONLY difference in Femto Lasik is that, we use FEMTOSECOND LASER to create the "Flap", instead of the Routine ‘Microkerstome Blade’ . That is why it is called “Bladeless”. (For eg. Intralase is the Femto-laser from the company Abbott and they call their femto flap creation as i-Lasik. Visumax is Femto laser from Carl ZEISS, ZEIMER-LDV Femto call theirs as Z-Lasik, Wavelight FS-200 (Alcon - CONTOURA VISION treatment), SCHWIND etc. (some other Femtosecond laser platforms like Lensx-Alcon, Catalys-Optomedica, Victus-Technolas B&L and so on are also there in market, which are actually used for Femto-"Cataract" surgery or FLACS).
The Flap in a Femto-Lasik is STILL DEFINITELY MADE (although not by a blade but by the Femto laser) and it will always be there on the Cornea (and so will remain the minimal chances of all the flap related complications which are mentioned everywhere on the internet, although theoretically slightly less, when the flap is made by laser as compared to Microkeratome Blade, THAT’S ALL). Finally after making the flap by Femto Laser, rest of the whole procedure is still carried out by the Excimer Laser (Lasik-Laser) only.
Because just to create the Flap, another altogether new laser, the "Femto-laser" comes into the picture, the cost goes almost 3 fold.
Q3. What is Flapless Lasik / SMILE ?
The ALL-FEMTO (NO EXCIMER & NO FLAP LASIK) called SMILE (‘SM’all "I"ncision "L"enticule "E"xtraction) which is a type of "F"emtolaser based "L"enticule "EX"traction (FLEX), is Definitely a revolutionary and the latest technique of refractive surgery which corrects the glasses number by cutting a highly accurate Intralamellar lenticule by the Femto-laser, within the thickness of upper half of the Cornea, which is dissected within the layers of cornea by special instruments and removed out of it by a small 20-30 degree (2.5-3.5 mm) incision (as compared to a nearly 300 degree circular cut of 21-24 mm in case of a Lasik-Flap, whether made by microkeratome-blade or Femto-Laser) thus removing the refractive error WITHOUT DOING ANY LASIK PROCEDURE BY THE EXCIMER LASER altogether !
This revolutionary technology is no doubt the FUTURE of refractive surgery, but the cost is 4-5 times than that of routine Excimer-Lasik and this technology is still not freely available in all lasik centres as it requires more expertise and a specific setup of laser equipment. Majority centres still do some form of Lasik only and not SMILE. Currently this technology is patented by company CARL-ZEISS by the name RELEX-SMILE (but all the others FEMTOSECOND laser company platforms are in pipeline of developing their own some sort of SMILE softwares, which should be available in the next few years by most companies)
But Remember. SMILE cannot treat "PLUS" numbers (HYPEROPIA) / "ONLY CYLINDERICAL" numbers and CAN'T DO CUTOMISED TREATMENTS as of yet ! (So it may not give you that "extra fine" vision or 6/5 vision but generally you will be able to reach a Normal vision of 6/6 without glasses most of the times which is comparable to that of Aspheric-profile Lasik) . (Although trials are going on in a few centers around the world including INDIA for HYPEROPIC-SMILE treatments and CUSTOM-SMILE treatments)
So a BRAND NEW era of SMILE technology is HERE, and it definately is here to STAY FOR GOOD ( but only if one can AFFORD it !)
Q 4. What are SBK-Lasik / PRK / LAS-E-K / Epi-Lasik ?
SBK Lasik (sometimes called ZED-Lasik) is Sub-Bowman Keratomeliusis which is recommended for thinner corneas, where your corneal pachymetry values may be less than 530 microns, or you have a high number to be ablated (more than 3.5 to 4 Dioptre) which requires some special thinner caliber-plate single use Microkeratome blades which make a thinner corneal flap of 90-95 microns instead of a routine 140-145 micron flap which needs little more expertise to handle n operate theoretically. Cost may be slightly higher than Normal Lasik but if one can afford , one should ALWAYS go for SBK-LASIK if your overall number is more than 3-3.5 dioptres or a lower than normal Pachymetry Values in ANY of your eye.
PRK or Photo-Refractive Keratectomy is a procedure where Excimer Laser ablation is carried out directly over the cornea after scrapping off the corneal epithelium (top most layer of corneal cells which is around 40 microns thick) either manually with a surgical instrument or with a rotatory motor, if your corneas are extremely thin and you still want your glasses removal surgery done. The epithelium takes 3-4 days to regenerate fully and till that time a bandage contact lens is put on your cornea post-PRK which is removed after 3-4 days to reduce pain in the eye and enhance corneal epithelial regeneration). PRK is generally "less well tolerated" than Lasik due to more post operative pain and discomfort (esp for first 3-4 days). But then it is still a great option whenever "flap" creation is NOT ADVISABLE.
A variation of this technique is Epi-Lasik (or E-Lasik) where instead of scrapping the epithelial layer by a mechanical debrider, a specialised automated microkeratome with a uniquely designed blunted blade is used to separate the epithelial layer very gentlly and Routine Lasik is performed over that. The sheet of epithelial cells may or may not be put back over the cornea. The Epithelial layer of cells may also be losened and mechanically removed with the assistance of some specially diluted Alcohol soaked swab, the technique which is called as "LASEK".
In Any of the above (PRK / LASEK or Epi-Lasik) a "Bandage Contact Lens (BCL) will be put over the cornea (to heel up the raw corneal surface) for 4-7 days. There will be slightly more pain than routine Lasik and the Vision may remain a little hazy and slightly fluctuating during this period which is normal for these kind of procedures.
Q.5 Is Lasik painful? Is any injection given? Will my eye have a pad or dressing after Lasik?
Lasik PER SE is a nearly totally PAINLESS procedure (unlike PRK/LASEK/Epi-Lasik). Of course there is some ‘tightening sensation’ and transient blackout of vision along with a buzzing sound of Microkeratome pass for only a few seconds when suction is built up on the cornea by a ring to ‘cut the Flap’, which is actually very "easily tolerated" if the patient just relaxes the eye, opens the eyes widely and doesnt squeeze or move the eye when the flap is being cut. The pressure built-up is much less when the flap is cut by Femto Laser so there may not be any blackout at all. When the actual Excimer laser ablasion procedure is being performed, there is some chattering noise of the Excimer laser shots falling on the cornea which is again painless. If the patient just keeps looking at the Green-Red blinking target fixation light within the machine ignoring the other lights & other sounds, the whole procedure will be complete within approx 20 mins for BOTH eyes in Microkeratome Lasik and around 40 min in Femto Lasik (SMILE procedure may take around 20-25 min too). The whole surgery is done by using just anaesthetic drops. There is no injection or eyepad whatsoever.
Q6. What if i Blink or move my eye unknowingly during laser procedure ? Will it harm my eye?
Your eyelids will be kept open throughout and till the end of the laser procedure by placing a small CLIP like instrument in between your lids called as an "Eyelid Speculum" which will keep both your eyelids apart and prevent you from accidental blink.
There is generally an eye tracker incorporated in most laser matchines which will automatically detect any GROSS misalignment from your eye and the laser will stop firing. But still as far as finer eye movements are concerned, the laser might keep firing till the time the eye tracker shows it is engaged. So patients are instructed to just keep looking CONSTANTLY and absolutely straight into the TARGET RED-GREEN LIGHT without making ANY eye movements once the laser starts firing.
Remember “The laser cannot see !” Its only the patient who has to consistently see the target blinking RED-GREEN indicator light of Excimer Matchine, in order to let the Laser work accurately. The more the eye movements, the more the percentage of inaccurate-waste laser shots are automatically fired, the more the chances of slight residual number remaining after the procedure, that’s all.
Rest NO harm can be done to the eye as such by the Excimer laser. LASIK in itself is one of the safest, most gratifying and highly accurate Laser guided surgery "ever designed by the human hands".
Q7. What is the success rate of the surgery? Any guarantee that 100% of number will be removed?
LASIK has more than 98-99% success rate. Of course no one in the world would give 100% success rate Guarantee esp. if your number is more than 4-5 dioptre (generally the aim is to correct around 90-95% of your power by the matchine, depending upon some technical data and normogram derrived protocols in every company laser platform. So there’s always a “slight chance” of .25 or .35 number remaining after surgery as your glasses number goes higher than 4-5 dioptres. But even if that slight number is left after surgery (which is not the case most of the times), you will generally NOT REQUIRE IT and you will be Practically "OFF THE GLASSES" for good. (0.25 to 0.5 glasses number is present in almost half the world's population. This doesn't mean that half of the people of this planet wear this half numbered glasses all the time !! )
Q8. When is a good time to get my lasik done?
Generally after the age of 18-19 years, if your number is stable for the last two or three 6-monthly visits and your ocular surface and corneal parameters are detected to be within normal limits, Lasik can be safely done on your eyes.
Q9. What are the tests required before Lasik?
For Pre-Lasik evaluation, you should discontinue wearing your soft contact lenses ideally for 3-4 days and certain tests like corneal thickness (Pachymetry) and corneal curvature mapping (Topography – Orbscan / Pentacam / Sirius etc) are done. An intra ocular pressure measurement & detailed fundus examination should also to be ideally done before lasik, to rule out any weak areas (WWP areas / Lattice degenerations) in your peripheral retina which may or may not require some other kind of laser treatment (Argon-Barrage Laser) a few weeks before lasik surgery.
Q10. Will my vision improve after Lasik?
A big “NO”.
VISION STAYS THE SAME after lasik, as it was earlier with the glasses.
For example, If you were able to read only the top 4 lines in the vision chart all throughout your life with your glasses (due to some XYZ reason), you will still be able to read till those top 4 lines only post lasik also, and NEVER BEYOND THAT !
REMEMBER, Lasik just removes your Glasses Power THATS ALL !!
Although they say that Topo-Guided / Wavefront-Guided Customized treatments can give you a 6/5 vision or beyond normal vision, but that is only if you have PROVEN higher order abberations detected on an abberometer machine, And again, there are still no 100% guarantees for that (as clear perception of image by the retina of our eyes is a far more complex bio-physiological process than just glasses number and also aberration errors of eye are very dynamic & tend to change with time). This is the reason why Wavefront Guided Custom treatments are sort of losing their charm these days over a period of time.
Q11. Can the number come back after Lasik? Can lasik be re-done again if number comes back after few years ?
Whatever number once corrected by laser STAYS CORRECTED. But if supposing your number was increasing just before your lasik was done, the additional number (which was supposed to come over and beyond your original number at that time which was corrected by laser) may start to show up few years after lasik again from zero power onwards. Though It may or may not be significant enough and you may avoid using it if you don’t feel the need for it.
Lasik Re-treatment may not be possible in every case that has landed up in glasses number again after few years post lasik (unless your pre-lasik corneal pachymetry was extra ordinarily good as confirmed on your pre-lasik records). There is always a small possibility that in or after pregnancy, your number might tend to come back slightly in some cases. Again you may or may not require it.
And of course there is NO DENIAL that YOU WILL DEFINITELY REQUIRE "READING GLASSES" for near work AFTER THE AGE OF 40 once you get rid of your distance number by lasik or SMILE.
Q12. What all and till what time i will need to take precautions & put eye drops after Lasik? Can i go to work next day after Lasik? Will my eye be painful or look red after surgery?
You can be back to work after a couple of days of rest but you should gradually start building up your hours of work (esp. for Computers / Screen work you might need to take more frequent breaks initially for few days ,whenever your eyes feel tired). Few minor precautions like not to rub the eye, no splashing of water directly inside eyes, no swimming and no eye make-up for 1-2 months (as the "flap" which is made, actually takes that much time for adhering to its full strength to the residual corneal bed surface). These precautions are to be kept definitely for a much smaller time in SMILE (as there is NO FLAP...! and the corneal cut size is also one tenth as compared to Lasik). Similarly, the eyedrops will continue for 1-2 months as well. Sometimes Lubricating eydrops may need to be put in some minimum dosage for as long as 3-6 months, depending on person to person & work profile as there is DEFINITELY SOME AMOUNT OF TEMPORARY DRY EYES FOR A FEW MONTHS REGARDLESS OF THE TYPE OF PROCEDURE YOU UNDERGO as the corneal nerves are anyways cut , (whether a Flap or No flap) which takes few months to regenerate properly (although theoretically stated much less in SMILE procedure literature from the last couple of years). And of course your eye might look a little red and feel little tired for a few days after Lasik which is transient and resolves soon with eyedrops.
Q13. What are the complications i may face after lasik?
There is always a slight chance of flap related complications in case of Lasik (not in SMILE) if you rub your eye or start eye makeup too soon in the immediate post operative period (in the form of flap displacement & Corneal / Flap interface swelling and related complications) if post operative instructions are not followed correctly. Mild discomfort and dryness are transient and resolves soon with eyedrops within few weeks.
Q14. Are there any long term side effects of Lasik?
Dryness feeling should resolve in a few months with eye drops. Most important long term side effect of Lasik is the very rare chance of cornea becoming slightly thinner that usual with the resurgence of glasses number, if your pre-operative glasses number to be ablated was very high (more than 8-9 dioptres) or the pre-operative assessment before lasik was less than Ideal. In most cases only slight number reappears which might require glasses again to give good vision.
In some extremely rare scenario, the cornea may slowly start showing deviation from its aspherical (circular) shape and start becoming ‘ECTACTIC’ (Conical or bulging). To strengthen such a weak and ectatic cornea (if detected in its early stage many years after lasik) there is a special procedure called as C3R (Corneal Collagen Crosslinking with Riboflavin). Sometimes C3R is performed along with Lasik in the same sitting for very high-risk Lasik patients. This is called Lasik-PLUS/ Lasik-Extra procedure. But it is always preferable to avoid any FLAP based procedure like Lasik, on high-risk Corneas. Rather a PRK with C3R (PRK Plus / PRK - Extra) is much safer option.
Q15. I have very high number. Any other option if Lasik can’t be done?
If you are having very high number (more than 7-8 Dioptres) or a very thin cornea which may have a chance of ECTASIA post-lasik, which renders you UNFIT FOR LASIK on pre-lasik workup, then there are specially designed contact lenses which can be permanently fitted by a special surgery in between your original lens of the eye and the back of your cornea. These lenses are called as PHAKIC-INTRAOCULAR LENSES which are available both in Indian (EYEPCL, RIL) and imported (ICL / PRL) brands). Although they are pretty costly but they ensure that no procedure is carried out on your cornea which may later damage it. And they are REVERSIBLE too (UNLIKE LASIK or SMILE which are IRREVERSIBLE procedures).
Also the original and clear lens of your eye can be removed just like in a cataract surgery and a specially calculated low power intra-ocular lens implant may be fitted in your eye to practically remove your glasses power if it is extremely high.
Q16. I want to get rid of reading glasses too. Is there any option ?
There is an option of CLEAR LENS EXTRACTION with MULTIFOCAL LENS IMPLANTS, and other Refractive Techniques like CONDUCTIVE KERATOPLASTY / Excimer-SUPRACOR or PRYSBYMAX procedure / Femto-INTRACOR / PRYSBEYOND or Laser Blended Vision Surgery & CORNEAL INLAYS procedure which are not routinely recommended in every case (discussion on which is beyond the scope of this article). It should be properly discussed with your operating eye surgeon as these techniques are still in some sort of experimental stages only with limited results and they lack high quality long term followup data worldwide (unlike LASIK and PHACO which have results proven beyond doubt for over decades now.)