Weakened Corneas

"Ruptures along RK incisions occurring 7and 10 years after RK suggest that some eyes with RK may never re gain full strength. Therefore, in addition to the commonly accepted risks inherent in RK, the potential candidates for RK must be apprised of the increased risk of ruptured globe after blunt trauma."

Ruptured Globes Following Radial and Hexagonal Keratotomy Surgery
(Arch Ophthalmol. 1996;114:129-134).

Paul F. Vinger, MD; William F. Mieler, MD; James H. Oestreicher, MD; Michael Easterbrook, MD

"Persons with occupations or, hobbies that increase the risk of trauma to the eyes should be excluded. This would include boxers, karate practitioners, race car drivers, etc." 

Dr Charles Casebeer, Incisional Keratotomy - 1995

"Radial keratotomy is a procedure that may permanently alter the corneal epithelium and endothelium, that certainly does scar the stroma, and that demonstrably weakens the eye wall's resistance to blunt trauma."

Dr Irving Schwab, Refractive Keratoplasty - 1987

Air Bag-related Corneal Rupture After Radial Keratotomy

Goldberg M., Valluri S. and Pepose J.

Amer Jour Ophthalmol , 120(6):800-802, 1995 Dec.

The authors report a case: a 29 year old state police officer status post 8 incision RK (to the limbus) with 3.0 and 3.5 mm optical zones was involved in a MVA at 35 miles per hour. His airbag deployed. He suffered a ruptured globe with dehiscence of 7 of the 8 RK incisions in addition to a full thickness corneal laceration. He required 31 10-0 nylon sutures for repair. Five months post operatively he achieved 20/25 vision with a comforatably fitting hard contact lens. The authors suggest PRK may be a better refractive choice for those persons at a higher risk for sustaining trauma and RK patients should be advised to wear protective lenses when driving.


Newer RK techniques that have larger optical zones and incisions not extending to the limbus have been reported in cadaver studies to have similar tensile strength as an unoperated eye. PRK may indeed be more advisable in persons at higher risk for trauma but the degree of myopia, planned surgical technique and surgeon skill also play significant roles when evaluating a patient for a refractive procedure.

Rupture Of Two Radial Keratotomy Incisions 19 Years Later, During A Clear Corneal Cataract Surgery

Audrey Baudot, Jean M. Perone, Adina Agapie, M Lacusteanu, P Lasota, S Kurun, H Mnasri and P J. Bertaux

Ophthalmology, Regional Hospital Center Bon-Secours, Metz, France

Commercial Relationships: Audrey Baudot, None; Jean M. Perone, None; Adina Agapie, None; M. Lacusteanu, None; P. Lasota, None; S. Kurun, None; H. Mnasri, None; P. J. Bertaux, None

Support: None Abstract

Purpose:The authors report the case of a multiple rupture of radial keratotomy (RK) incisions which occurred during a clear corneal microcoaxial phacoemulsification 19 years after refractive surgery.

Methods:Operated 19 years earlier by RK for a bilateral moderate myopia (about - 5 D), a 62- year-old woman was referred to us for the decline of her left one-sided visual acuity because of evolved cataracts. Realized in 1991, RK happened without particular incident. 4 incisions of 3mm of length and 500μ m of depth were made from the edge of the outer clear zone to the periphery, leaving a small margin of uncut cornea at the limbus. The BCV A were of 160/200 P2 for her right eye with a correction of -4.00 (0° -1.50) D and 80/200 P3 for her left eye with -7.00 ( 160° -2.75 ) D. The patient presented evolved bilateral nuclear cataracts so an indication of clear corneal cataract surgery of her left eye was retained. The scars of RK were noted down as almost hard to see in preoperative.

Results:The microcoaxial clear corneal phacoemulsification (2.2mm incision, stellaris Bausch&lomb,Rochester, NY) happened without incident until the end of the phase of divide and conquer where a sudden collapse of the anterior chamber was noted, complicated with a break of the posterior capsule. After the interruption of the operation, it appeared that both superior corneal incisions located on the axes of 70 and 110° had completely opened, explaining the collapse of the anterior chamber. After a suture of the two worn-out sections, each by two separated points of nylon 10/0, the intervention could start again and allowed a cleaning of the anterior chamber, a complementary anterior vitrectomyand a final implantation with a MTA4UO IOL of 17 D ( Alcon labs, Forth Worth, TX). Post operatively, no complications were noted. After sutures ablation 2 months later, the BCV A on this left eye was of 120/200 with a correction of -1.00 (100 ° + 2.00) D.Conclusions:Only two similar cases were described in literature: in 1998 by Budak and in 2001 by Behl. In both cases, the break of RK scar concerned only a single scar and had arisen very early after the KR for the first case (9 months later), and 11 years later for the second. Our clinical case shows that even 20 years after RK, the corneal fragility is such that a break may arise during clear corneal phacoemulsification. When the main met problem concerns today the biometric calculation of the implants, we warn against the rupture always possible of old RK incisions, even 20 years after the procedure.

Quality of Vision

"Disability glare, defined as glare that disrupts daily activities, occurs rarely, but a few patients find it necessary to curtail night driving, to use sunglasses, or to change their occupation."

Statement on Radial Keratotomy, George O Waring III -1988

"Similarly, persons In occupations with high visual demands such as engineers, surgeons, and writers need careful counseling about expectations and also need to be told that a complication could interfere with their current occupation."

Dr Charles Casebeer, Incisional Keratotomy - 1995

Binocular vision complications after radial keratotomy.

Duling K, Wick B. Source College of Optometry, University of Houston, Texas. Abstract

Radial keratotomy (RK), a popular procedure for reducing myopia, does not always have a successful outcome. Of the adverse effects reported in the literature, there have been few reports of undesirable disturbances of binocular vision. Four representative cases are reviewed which presented clinically with varying binocular problems induced by RK. The treatment considerations and final solutions for each are discussed. In the presence of RK-induced anisometropia, aniseikonia can be a particularly debilitating binocular vision problem for some patients.

Contrast Sensitivity and Glare Disability After Radial Keratotomy 

Alaa A. Ghaith, MD; Jan Daniel, MD; R. Doyle Stulting, MD, PhD; Keith P. Thompson, MD; Michael Lynn, MS

Arch Ophthalmol. 1998;116:12-18. ABSTRACT

Objectives To study the effects of radial keratotomy (RK) and photorefractive keratectomy (PRK) on contrast sensitivity and glare disability using 4 different devices, and to correlate subjective complaints with objective scores of visual performance.

Methods Preoperative contrast sensitivity for 30 eyes undergoing RK and 30 eyes undergoing PRK was compared with contrast sensitivity at 1, 3, and 6 months postoperatively using the CSV 1000, MCT (Multivision Contrast Tester) 8000, and Pelli- Robson chart. The BAT (Brightness Acuity Tester) and MCT 8000 were used to test for daytime and nighttime glare disability, respectively. At 3 and 6 months postoperatively, a questionnaire was administered to assess visual performance subjectively.

Results Contrast sensitivity decreased after RK and PRK up to the sixth postoperative month, while glare disability was significantly increased at 1 month after PRK as determined by the MCT 8000 and the BAT, and at the third and sixth months after RK using the MCT 8000. Compared with RK, PRK significantly decreased contrast sensitivity as measured with the MCT 8000 at all spatial frequencies 1 month postoperatively. No significant difference in visual performance between patients undergoing RK and PRK was observed with the CSV 1000, the Pelli-Robson chart, or the BAT up to 6 months postoperatively. No consistent difference was found between glare disability scores of patients undergoing RK and PRK when measured with the MCT 8000. Subjective reports of problems with night driving and blurring correlated only with glare disability scores of the MCT 80003 months after RK.

Conclusions Both RK and PRK reduce contrast sensitivity and cause glare disability; however, the relative effect is highly dependent on the time postoperative testing is performed and the instrument used for testing. Contrast sensitivity and glare disability, as measured by the instruments used in this study, do not accurately reflect patients' subjective assessment of visual performance in daily life.

Penetrating Keratoplasty for Severe Complications of Radial Keratotomy

Hersh, Peter S. M.D.; Kalevar, V M.D.; Kenyon, Kenneth R. M.D.


Severe sight-threatening complications were seen in five eyes of three patients following improperly performed radial keratotomy. All patients exhibited neovascularization of the incision sites, severe stromal scarring or ulceration involving the visual axis, loss of the anterior chamber, and iridocorneal adhesions. These complications necessitated multiple and complex surgical interventions, including penetrating keratoplasty and anterior segment reconstruction. Final visual acuity was decreased to light perception in four eyes while one eye achieved 6/60 vision following repeated penetrating keratoplasty. The success and safety of radial keratotomy rely on careful case selection, appropriate instrumentation, specialized training, and the ability to perform complex secondary procedures to correct surgical complications.

This photo shows how a lot of RK patients see at night.

screen shot 2012-10-18 at med

To See more similar photos, go to


"Vascularization of incision scars : Most refractive keratotomy scars heal without vascularization.  Events that stimulate vascularization of the scar include incisions across the limbus, wearing of contact lenses— particularly extended wear soft lenses, cautery at the limbus, and inflammation or infection in the scars."

Refractive Keratotomy, George O Waring -1992

"In the PERK study 1 year after surgery, 1.5% of the incisions demonstrated vascularization, not extending more than 1 mm ,but after 3 years, progression of vascularization was noted in 16 eyes (3.6%), extending 5% to 50% of the length of the incisions.  All but three of these patients had worn a contact lens....Most vascularization of the wounds occurs subepithelially, but if a stromal vascularization is induced, the patient may be at a higher risk of allograft reaction if a penetrating keratoplasty is needed in the future."

Dr George O Waring III, Refractive Keratotomy - 1992

This photo shows how the blood vessels can follow the RK scars.

Brent Jesperson-neovascularisation to entrance pupil
pasted-file-70 med
pasted-file-69 med
pasted-file-71 med


After a decade of patient followup.....the study found that more than 40 percent of RK-operated eyes continued to have a gradual shift toward farsightedness.

National Institutes of Health

National Eye Institute

October 13, 1994

June 2003

5 Questions With R. Bruce Grene, MD

Dr. R. Bruce Grene reflects upon his 20 years as an ophthalmologist and the insights he has gained.

By R. Bruce Grene, MD

You have participated in a number of research projects during your 20 years in practice. Which do you feel were most significant? My role in commercializing Celluvisc (Allergan, Inc., Irvine, CA) certainly ended up touching the most lives. Proving an artificial tear could be therapeutic was quite novel. In addition to demonstrating the reversal of squamous metaplasia, we also changed the way in which eye doctors practice. The grab-bag use of toxic, preserved multi-dose tears was replaced by the selection of specially formulated, anionic, unit-dose vials. The Celluvisc formulation went on to become the world’s leading artificial tear.

What are your research interests today? Not a day goes by without my contemplation of how to help patients with post-RK syndrome. Finding a safe, effective surgical treatment for hyperopia, fluctuation, and irregular astigmatism is a big challenge. The Grene Lasso works, but this procedure is technically challenging and temporary. I am currently studying mitomycin C- enhanced PRK, and the early results are excellent. I feel this path will lead to wavefront-driven, customized surface ablation and significantly improved vision quality. It is exciting to help those patients from decades ago who did not have the benefit of today’s advanced technologies.

What prompted you to write a textbook on comanagement? My dad was a small town doctor, and I actually began practice as a general practitioner. Having seen medical care from the primary care perspective, I wanted to explore the importance of coordination between optometrists and refractive surgeons. The book is entitled Patient Centered Comanagement, and I think comanagement has matured to fit this description. The political and economic influences have diminished, and most comanagement arrangements start with “what’s best for the patient?” The 3-year lull in refractive surgery has led to a de-emphasis on comanagement within many practices, but soon refractive surgery results will begin to equal or exceed those of spectacles or contacts. This will fuel new growth of refractive surgery and once again bring comanagement issues to the fore.

You have spoken and written about practice structure and management. How does your practice compare to your theoretical model? Fifteen years ago, Paul Starr, a sociology professor at Princeton University, wrote about the impending domination of medical practice by vertically and horizontally integrated corporations. I have spent the last 13 years building an integrated practice—but without the corporation. Grene Vision Group is a traditional, doctor-owned group practice that exemplifies the best attributes of a regional scale combined with a balance between doctors’ autonomy and accountability. My participation in the ongoing evolution of our group has been the most important creative project of my professional life. With 12 ophthalmologists, 21 optometrists, 275 staff members, and 19 locations, it is certainly the biggest project as well.

What has been the most interesting aspect of your 2 decades in refractive surgery? During that time, refractive surgery has grown from its infancy into a global business and true medical subspecialty. It has been a thrill and a privilege to go along for the ride. Today, as refractive surgery is poised to enter its third period of growth (following the Casebeer and LASIK eras), it is appropriate to recognize that we stand on the shoulders of all those men and women who held a constant and passionate conviction about the future of refractive surgery. That future is here, and I am excited to be a part of it. As productive as the past 2 decades have been, the best and most productive era still lies ahead.

The lasso was invented as a temporary cure for the more than 40% of patients that became hyperopic. ( ten year PERK study)


"The potential of this procedure to render good uncorrected visual acuity must be weighed against its known risks. Refractive side effects include anisometropia (imbalanced vision), increased astigmatism, and early symptomatic presbyopia (loss of near focus in middle age) in overcorrected patients. Other side effects include prolonged unstable vision and mild glare. Complications that  produce loss of vision are extremely rare. These include ocular infections and increased risk of rupture of the cornea following severe trauma."

Statement on Radial Keratotomy, George O Waring III - 1988

"No matter how justified the procedure may seem on the basis of physical and refractive qualifications, the decision for surgery must depend on knowledge and understanding of the risks versus the benefits, and that decision must lie with the patient"

Dr Spencer Thornton, Radial and Astigmatic Keratotomy - 1994

0001ev 2


Volume 93, Issue 3 , Pages 319-326, 1 March 1986 

Visual impairment following radial keratotomy. A cluster of cases

Thirteen patients who underwent radial keratotomy developed complications leading to visual impairment. Three eyes were legally blind. Two groups of complications were seen: those common to surgical procedures involving the eye--optic atrophy, infections, cataract and retinal detachment, and those unique to radial keratotomy--complete failure of the procedure, marked undercorrection, marked overcorrection, and induced astigmatism. Symptoms due to anisometropia were prominent in the latter group who considered themselves visually disabled by the surgery. Radial keratotomy, like all surgical procedures, is liable to complications that may lead to visual impairment, blindness, or loss of an eye.

Fluctuating Vision

"The unsutured wounds in the avascular cornea heal slowly, requiring at least 4 to 5 years to completely eject the epithelial plug  and to remodel the stroma adjacent to the incision scar.  Persistent diurnal fluctuation of vision occurs up to 3 years after surgery, and some patients notice it as long as 5 years after surgery."

Statement on Radial Keratotomy, George O Waring III - 1988

Corneal topography and fluctuating visual acuity after radial keratotomy

A high-resolution photokeratoscope using computer graphics to model corneal topography was used on patients who had undergone radial keratotomy. After radial keratotomy, central optical zones are created that can be characterized as round, oval or band-like, or dumbbell-shaped or split. The dumbbell form of optical zone was associated with larger amounts of refractive and keratometric astigmatism than the round or band-like zones. The authors correlated the shape of the optical zone with the presence or absence of diurnal variation (fluctuation) in visual acuity. Of the 26 eyes studied, 11 experienced fluctuation and 15 did not. Of those 11 eyes with fluctuating visual acuity, 10 (91%) had dumbbell-shaped or split optical zones and 1 (9%) had a round optical zone. Of the 15 eyes without fluctuation, 12 (80%) had round optical zones and 3 (20%) had band-like zones. The presence of a split or dumbbell-shaped optical zone after radial keratotomy indicates that the patient is likely to experience diurnal fluctuation of visual acuity.


"Most of the lens opacities occurring after refractive keratotomy have resulted from direct laceration of the lens at the time of a corneal perforation. This is one time when the diminutive term "microperforation" takes on a more onerous meaning. This complication was not only limited to the early 1980s when metal-bladed knives and cruder techniques were used; we are
aware of cases in the late 1980s. Direct laceration of the lens is most likely to occur when the surgeon uses new techniques or instruments that cause deeper incisions in the cornea, when the surgeon is careless or in a hurry , when the patient moves inadvertently in the midst of an incision, and during deepening incisions.  Other causes of cataracts after keratotomy surgery include endophthalmitis and prolonged topical corticosteroid use."

Refractive Keratotomy, George O Waring -1992

"Topical corticosteroids are used after refractive keratotomy for three reasons:  1) to decrease the postoperative mild inflammation of the cornea, a use that can be effective with in less than a week, at which time the steroids should be stopped; (2) to enhance the effect of the surgery by presumably retarding wound healing in patients who retain normal intraocular pressure, a use that has been supported by one report"; and (3) to enhance the effect of the surgery by elevating the intraocular pressure, an effect that is clearly demonstrative on the short term , but the long-term benefit has never been documented.  Surgeons should guard against the chronic use of topical corticosteroids to affect the outcome of refractive keratotomy because of the danger of optic nerve damage from elevated intraocular pressure and of the induction of posterior subcapsular cataracts."

Refractive Keratotomy, George O Waring -1992

"A small number of cases of cataract formation have been reported to date. Five followed perforation into the anterior chamber....Two cases of steroid-induced cataract formation have been reported.  In each case the surgeon was attempting to enhance the effect of the surgery by inducing an IOP rise with topical steroids . It has not been shown that increasing the IOP above normal has any permanent effect on the outcome of the surgery; nonetheless, some surgeons persist in this attempt.  Because of the serious side effects reported with long-term topical steroid usage, this method of "treating" undercorrection is not recommended. "

"The major vision-threatening complications of radial keratotomy have until recently been limited to case reports of endophthalmitis and cataract."

Dr Irving Schwab, Refractive Keratoplasty - 1987


Cataract surgery after radial keratotomy can be challenging

Inaccurate IOL calculations, extended postop recovery and patients’ mindset create the possibility of a difficult procedure.

Many of the patients who had radial keratotomy surgery in the ’80s and ’90s are now developing visually significant cataracts.

Because of their irregular corneas, even mild cataracts can induce visually significant aberrations at an earlier stage than would be expected for a traditional patient. This is a difficult subset of patients for many reasons: The IOL implant calculations can be inaccurate, the surgical procedure can be challenging, and the postoperative recovery can be prolonged. However, the greatest challenge is often the mindset of the refractive patient. These patients often have high demands and are frequently intolerant of residual refractive errors.

IOL selection

Many formulas and techniques have been described for calculating IOL power in post-radial keratotomy (RK) patients. This tells me that there is no single method that yields great results. The principal error in calculation is overestimation of the corneal power, which results in implantation of a lower power IOL and postop hyperopia. Because these patients have typically been myopic their entire lives, leaving them with residual hyperopia is particularly uncomfortable and Uday bothersome. To help prevent postop hyperopia, a more myopic result can betargeted, such as –0.75 D instead of the typical –0.25 D.


In patients with no old records, the method that I use most often to calculate corneal power was proposed by Robert K. Maloney, MD. It uses the central corneal power as measured by topography and therefore does not depend on history. The power of the cornea is a combination of the anterior corneal power and the posterior corneal power. By converting the overall central corneal power from topography back to the anterior corneal power, then subtracting the expectedposterior corneal power, we can achieve a fairly accurate estimation for our IOL calculations. This formula is:

Estimated K power = (Central K power on topography × 376/337.5) – 6.1

Because of the irregular corneas, I prefer to avoid multifocal IOLs, instead preferring single focus lens implants. Aspheric IOLs may be a particularly good choice in these patients because of their significant corneal aberrations.

Implanting a negative spherical aberration aspheric IOL can help to offset the large amount of positive spherical aberration often seen in RK corneas. In this case, I prefer the Advanced Medical Optics Tecnis IOL, as it has the best ability to offset large degrees of corneal positive spherical aberration. When the corneal aberrations are not known and a degree of irregularity and other higher order aberrations are suspected, I prefer the Bausch & Lomb SofPort Advanced Optics, as it has zero spherical aberration and is the “do no harm” IOL that will not confound the aberrations.

Intraoperative considerations

The RK incisions are weak and are prone to opening during surgery. Any incisions made during cataract surgery must avoid intersecting the existing RK incisions, lest they unzip and cause excessive fluid leakage during surgery. In patients with previous 8-cut RK, clear corneal incisions can be made between the existing RK incisions. (Figure 1). In patients with 16-cut or more RK, it becomes difficult to avoid the existing RK incisions unless a scleral tunnel cataract incision is used (Figure 2).

To be gentle on the weakened cornea, I prefer lower flow and a lower bottle height with a smaller phaco needle to ensure that the fluid inflow still stays greater than the fluid outflow. If the RK incisions open during surgery, be aware that there could be sudden instability and shallowing of the anterior segment, and the chance for capsule rupture is increased. At the end of these surgeries, I like to paint the entire cornea with fluorescein dye to check for any leaks, which can easily be sutured while the patient is in the operating room.

Postop recovery

The RK incisions swell during even the gentlest cataract surgery, and this swelling can induce central corneal flattening, which results in excessive hyperopia immediately postop. These RK patients will experience fluctuations in their refractive state for many weeks after their cataract surgery, so a mild amount of initial hyperopia should not be a cause of concern. After waiting at least 6 weeks, if the patient is still significantly hyperopic, a second procedure can be performed.

Perhaps the most important issues in RK patients with cataracts are explaining to them that their IOL calculations are, at best, estimations and that their surgery and postop recovery will likely be more challenging for the surgeon and the patient.


"Functionally significant irregular astigmatism occurs most commonly in eyes that have had repeated operations or "creative keratotomy," consisting of intersecting radial and transverse incisions, combined radial and circumferential incisions, or incisions that extend too close to the line of sight. Such irregular astigmatism can greatly reduce visual function, not only decreasing spectacle-corrected visual acuity, but also producing glare and light sensitivity."

Dr George O Waring III, Refractive Keratotomy - 1992

"The most common examples, of improper RK technique are too many re operations and transverse incisions that cross or touch radial incisions. Both of these can lead to improper wound healing and frequently irregular astigmatism"

Dr Frank Thompson, Myopia Surgery - 1990

"Early techniques frequently used 16 and occasionally 32 incisions.  The profound corneal instability and irregular astigmatism that resulted from these additional incisions became increasingly undesirable and unnecessary as better results were obtained from eight, six, and often four-incision techniques."

Smolin and Thoft, The Cornea - 1994

Irregular astigmatism after radial and astigmatic keratotomy.

McDonnell PJ, Caroline PJ, Salz J


Doheny Eye Institute, University of Southern California, School of Medicine, Los Angeles. 


Eleven eyes of six patients, who had been referred for management of irregular astigmatism after receiving crossed incisions for myopic astigmatism, had moderate to marked irregular corneal astigmatism with marked flattening in the meridians of intersecting incisions. All six patients had a decrease in best-corrected visual acuity with spectacles after surgery. Visual acuity with spectacles was 20/40 in five of 11 eyes; with contact lenses it reached 20/40 in ten of 11 eyes. However, two patients could not wear the contact lenses because of lens decentration caused by the marked distortion in corneal topography. Even with contact lenses, visual acuity could only be improved to 20/25 or better in six of 11 eyes.


2912115 [PubMed - indexed for MEDLINE]