Journal of Refractive Surgery

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Consultations 

MANAGEMENT OF HYPEROPIC SHIFT AFTER RADIAL KERATOTOMY

Spencer P Thornton, MD

Abstract

CASE PRESENTATION

In 1983, a 42-year-old professional man presented with myopia and astigmatism of OD -8.00 +2.00 × 100 and OS -6.50 +1.50 × 95 and a history of difficulty wearing contact lenses and thick glasses. K-readings were OD 42.75 × 180/44.00 × 95 and OS 42.50 × 175/44.00 × 90. His corneal thickness was 560 to 570 µ centrally, 610 µ at the 3-millimeter zone and 780 to 800 µ at the 9-millimeter zone.

In March 1983, he underwent a 16-incision radial keratotomy in the left eye using a 3-millimeter clear zone. The initial incisions were made with a diamond blade carried centrifugally and deepened with a steel blade carried centripetally to a 7-millimeter zone. Two months later, a similar procedure was performed on the right eye.

Three months postoperatively, his refraction was OD -1.50 +0.50 × 165 and OS piano sphere with uncorrected visual acuity of OD 20/40 and OS 20/20. At 6 months, his refraction was OD piano +0.50 × 170 and OS piano, and at 1 year, he corrected to 20 /20 with OD +0.25 +1.00 × 160 and OS +0.75 sphere. At 2 years, his refractive error had changed to OD + 0.50 +0.75 × 175 and OS + 1.75 sphere. In 1986, 3 years after surgery, his refraction was OD +2.50 + 3.00 × 165 and OS +2.50 +1.50 × 170. By 1991, his hyperopia had increased to OD +4.75 +3.25 × 175 and OS +5.75 + 1.00 × 90. The patient, a busy professional, is still bothered by fluctuation of vision requiring the use of several pair of glasses during the week. In view of this continued hyperopic shift, please give your analysis and recommendations based on your experience with simitar cases.

Question provided by Spencer P. Thornton.MD

RESPONSES

The occurrence of progressive hyperopia and increasing against-the-rule astigmatism 3 to 5 years after radial keratotomy (RK) surgery, has been well documented by several investigators. The incidence of these two complications appears to increase the smaller the optical zone and the greater the number of incisions. It is also known that flattening of the cornea and increasing against-the-rule astigmatism also occur with aging in unoperated individuals, but to a much lesser degree. These phenomena following RK surgery most likely represent an acceleration of the normal structural change of the cornea.

The fluctuations in vision following RK surgery are due to an increase in the hydration of the cornea while sleeping, followed by a gradual reduction upon awakening. Ninety percent of this change occurs within the 1st 2 to 3 hours after awakening, and is accompanied by a shift toward myopia. The remaining 10% of the daily refractive change is often the most annoying to the patient and doctor, because this change is very gradual and may persist throughout the remainder of the day.

I usually give the patients two pair of glasses - "morning* and "afternoon* spectacles. These two different prescriptions are determined empirically by refracting the patient about 9:00 in the morning and again at 4:00 or 5:00 in the afternoon. If glasses provide unsatisfactory vision, then I recommend rigid gas permeable contact lenses. They are often difficult to fit due to the irregular corneal shape, but perseverance can yield an 80% success rate in these patients.

If the vision is unacceptable with glasses (usually less than 20/50) or a contact lens cannot be fitted or tolerated, a corneal transplant is recommended. I use an 8.00-millimeter recipient bed, an 8.25-miUimeter donor button, and usually 16 radial 10-0 nylon interrupted sutures. If any of the remaining peripheral parts of the RK incisions can be…

CASE PRESENTATION

In 1983, a 42-year-old professional man presented with myopia and astigmatism of OD -8.00 +2.00 × 100 and OS -6.50 +1.50 × 95 and a history of difficulty wearing contact lenses and thick glasses. K-readings were OD 42.75 × 180/44.00 × 95 and OS 42.50 × 175/44.00 × 90. His corneal thickness was 560 to 570 µ centrally, 610 µ at the 3-millimeter zone and 780 to 800 µ at the 9-millimeter zone.

In March 1983, he underwent a 16-incision radial keratotomy in the left eye using a 3-millimeter clear zone. The initial incisions were made with a diamond blade carried centrifugally and deepened with a steel blade carried centripetally to a 7-millimeter zone. Two months later, a similar procedure was performed on the right eye.

Three months postoperatively, his refraction was OD -1.50 +0.50 × 165 and OS piano sphere with uncorrected visual acuity of OD 20/40 and OS 20/20. At 6 months, his refraction was OD piano +0.50 × 170 and OS piano, and at 1 year, he corrected to 20 /20 with OD +0.25 +1.00 × 160 and OS +0.75 sphere. At 2 years, his refractive error had changed to OD + 0.50 +0.75 × 175 and OS + 1.75 sphere. In 1986, 3 years after surgery, his refraction was OD +2.50 + 3.00 × 165 and OS +2.50 +1.50 × 170. By 1991, his hyperopia had increased to OD +4.75 +3.25 × 175 and OS +5.75 + 1.00 × 90. The patient, a busy professional, is still bothered by fluctuation of vision requiring the use of several pair of glasses during the week. In view of this continued hyperopic shift, please give your analysis and recommendations based on your experience with simitar cases.

Question provided by Spencer P. Thornton.MD

RESPONSES

The occurrence of progressive hyperopia and increasing against-the-rule astigmatism 3 to 5 years after radial keratotomy (RK) surgery, has been well documented by several investigators. The incidence of these two complications appears to increase the smaller the optical zone and the greater the number of incisions. It is also known that flattening of the cornea and increasing against-the-rule astigmatism also occur with aging in unoperated individuals, but to a much lesser degree. These phenomena following RK surgery most likely represent an acceleration of the normal structural change of the cornea.

The fluctuations in vision following RK surgery are due to an increase in the hydration of the cornea while sleeping, followed by a gradual reduction upon awakening. Ninety percent of this change occurs within the 1st 2 to 3 hours after awakening, and is accompanied by a shift toward myopia. The remaining 10% of the daily refractive change is often the most annoying to the patient and doctor, because this change is very gradual and may persist throughout the remainder of the day.

I usually give the patients two pair of glasses - "morning* and "afternoon* spectacles. These two different prescriptions are determined empirically by refracting the patient about 9:00 in the morning and again at 4:00 or 5:00 in the afternoon. If glasses provide unsatisfactory vision, then I recommend rigid gas permeable contact lenses. They are often difficult to fit due to the irregular corneal shape, but perseverance can yield an 80% success rate in these patients.

If the vision is unacceptable with glasses (usually less than 20/50) or a contact lens cannot be fitted or tolerated, a corneal transplant is recommended. I use an 8.00-millimeter recipient bed, an 8.25-miUimeter donor button, and usually 16 radial 10-0 nylon interrupted sutures. If any of the remaining peripheral parts of the RK incisions can be opened easily, the exposed stromal edges are scraped free of epithelial cells and closed with tangential 10-0 nylon sutures. By 6 months after the corneal transplant procedure, most of the sutures have been removed. The patient then receives spectacles or a gas permeable lens. In my hands, approximately 50% of these patients need a rigid gas permeable lens to achieve stable 20/20 vision, while the other 50% wear spectacles. Almost none of the patients are able to have acceptable vision without either spectacles or contact lenses.

JACK T. HOLLADAY, MD

Houston, Tex

This case demonstrates one of the things we all dread - a result that seems perfect at first, but then gradually descends into a refractive disaster. The result seems almost unbelievable (except that I have had the same thing happen) - between 11.00 and 13.50 diopters of effect! In retrospect, I would have done only eight incisions, but I doubt if that would have prevented this overcorrection. Four would have been about right but in that case you probably would have gone back and added cuts because you would not have known the hyperopic progression was coming. On the other hand, you can see the trend developing - at 6 months the tendency was there. The depth of the incisions is not given, but if they were super deep it might have contributed to the progression.

The handling of this problem is bound to be disappointing. Suturing the wounds, after curettage, either individually or by purse string is probably the best approach. However, this technique is easier to talk about than perform. It is difficult and the results, in my experience, at best are marginal. On the other hand, there is nothing to lose by trying it. What are the other possibilities? Theoretically, they would include thermokeratoplasty, hexagonal keratotomy, hyperopic keratomileusis, photorefractive keratectomy, and epikeratoplasty. Perhaps the newer thermal techniques would be helpful, but so far the results seem mostly temporary. Hexagonal keratotomy would be undesirable because of the need to cut across previous incisions, even though they are 8 years old. Hyperopic keratomileusis is certainly a possibility, but it would require a homoplastic donor and would be subject to its unpredictability.

Photorefractive keratectomy, while theoretically possible, has yet to be proven in this situation and would certainly not help the instability of the refraction. Epikeratoplasty, on the other hand would give added strength to the cornea and might possibly help the diurnal variation. IMs is something that might be worth trying. One last consideration would be the application of some transverse incisions to improve the astigmatism and perhaps gain daily wear soft lens tolerance. A hard lens would be better because it solves both the variable vision and the residual refractive error. Nevertheless, this case presents a situation where it will be extremely difficult to achieve patient satisfaction.

RICHARD ELANDER, MD

Santa Monica, Calif

This patient represents with progressive hyperopia after 16-incision radial keratotomy for myopia. This represents one of the most common complications of radial keratotomy, and underlines the potential for problems when performing more than eight or 12 semi-radial incisions in the cornea. I believe that the fluctuation in vision which this patient is experiencing is due to various factors, including diurnal fluctuations in corneal hydration, as a result of the instability of the ocular surface resulting from excessive wound gape. The cornea is unstable, and to correct the hyperopia and stabilize the ocular surface, these incisions need to be reopened and sutured to promote wound healing.

A trial of contact lenses should be attempted. If the patient cannot tolerate contact lenses, a surgical approach could be undertaken.

The approach I would recommend in this case would be to split open eight of the incisions (every second one) with a blunt instrument such as a Sinskey hook, and remove any epithelial plugs by irrigating with balanced salt solution. I would then suture each opened incision by placing a single deep 10-0 or 11-0 Mersilene suture (75% depth) at an optical zone of 7 mm as described by Lindquist. These sutures would be tied with a slip knot and adjusted with intraoperative quantitative keratometrie control, then tied with a square knot and buried. Since the spherical equivalent is + 6.25 in each eye, I would try to steepen the cornea by about 12.00 diopters assuming a greater than 50% decay in effect postoperatively. The keratometry should also revert to spherical with appropriate selective intraoperative suture adjustment. If not enough steepening can be obtained by suturing eight incisions, then all 16 incisions should be fractured and sutured as described above. Additional sutures at a 5-millimeter optical zone may further augment the effect. This approach allows for selective suture removal postoperative if necessary. The Mersilene suture should be quite permanent if an adequate result is obtained.

I prefer using interrupted sutures rather than a circular purse string suture, as the circular suture cannot be adjusted in a selective fashion postoperatively. If an adequate result cannot be obtained with the above approach, a homoplastic hyperopic keratomileusis may be considered.

PETER J. AGAPITOS, MD

Ottawa, Canada

The case presented demonstrates the progressive hyperopic shift first described by Dietz and Sanders, and all refractive surgeons who carefully analyze their data can point to similar cases. Although even in 1983 I would personally not have performed a 16-incision radial keratotomy (RK) with peripheral redeepening, I feel that even with an eight-incision approach this patient would have demonstrated a similar course although perhaps not quite as marked. In fact, 3 months postoperatively he was still slightly undercorrected in the right eye and piano in the left eye showing that the original surgical plan was appropriate. The hyperopic shift actually became most pronounced between years 2 and 8.

The largest overcorrection I have personally experienced was approximately +3.5 and this case was corrected nicely with eight interrupted Mersilene sutures at the 7-millimeter optical zone as described by Lindquist and Lindstrom. This case is now 3 years postoperative and has a refractive error of piano - 1.00 × 180 with 20/40 uncorrected vision. These sutures were tied tightly and resulted in a marked overcorrection which gradually faded and I think these suturing techniques are uiilikely to correct more than 2.00 to 3.00 diopters of hyperopia. This would obviously be inadequate in this patient.

Although the hobnium thermokeratoplasty procedure is being investigated for hyperopia, both in the US and in Germany, I think this procedure would be dangerous in a patient with a 16-incision RK as the contracture around the laser sites could well have an adverse effect on the RK incisions, and as far as I know, this procedure has not been attempted for postradial keratotomy hyperopia.

That would leave only two options for this patient. One would be a hyperopic epi procedure using fresh tissue and the other would be a homoplastic keratomileusis procedure. I would probably refer this patient to a surgeon who has experience with both of these techniques and let the patient choose the procedure he feels is best suited for him after the risks and benefits are discussed by the surgeon.

Unfortunately, as the years of follow up on our patients increase, I am afraid that we are going to see more and more cases like this. I think this demonstrates the wisdom of trying to end up with an initial under correction, using the minimal number of radial keratotomy incisions, hopefully to minimize the number of eyes that will demonstrate this shift. I think this progressive hyperopic shift is one of the biggest potential disadvantages of radial keratotomy. It is certainly frustrating for a surgeon and a patient to end up with an ideal result at 1 year only to see that result become extremely hyperopic 4 or 5 years down the road as occurred in this case.

This is one area where I think photorefractive keratectomy with the excimer laser will have a clear-cut advantage over the RK operation which works by structurally weakening the cornea. Unfortunately, we have no way of predicting which patients will demonstrate this hyperopic shift preoperatively.

JAMES J. SALZ, MD

Los Angeles, Calif

This case represents a major problem that is yet to be solved with radial keratotomy. There is no doubt that this gentleman would have been considered an extremely successful radial keratotomy (RK) case at his 3-month visit. Especially since he was 42 years old at the time of surgery, he had what I would consider my ultimate desired result of mild residual myopia in one eye and piano in the other. His progressive hyperopia over the last 8 years has obviously been very dramatic and Fm sure an extreme disappointment and frustration to the patient.

I think much work needs to be done analyzing patients such as this to find out whether there was any way to find out the cause of the progressive hyperopia. We all know that this is not a universal problem and it is the exception rather than the rule. I have always felt that a 16-incision multiple depth RK leaves a much more unstable cornea than fouror eight-incision RK with a single depth incision. Although there have been some reports of progressive hyperopia with four-incision RK, the definite studies on the effect of the number of incisions or the depth of the incision on progressive hyperopia has not been reported to date.

In this particular patient I feel secondary surgical intervention is warranted. I have had success with this type of patient in doing a 10-0 Mersilene or prolene purse-string suture and this can be either with a single suture at a 7.00-millimeter zone or a double suture technique with one at 6.5 mm and one at 8.5 mm, In this case, because of the large degree of progressive hyperopia, I would probably attempt a double suture technique.

The patient should understand that although this will most likely decrease the amount of hyperopia, that there is still very little known about the cause of the progressive hyperopia and I would certainly suggest doing one eye at a time.

Unless the problem of progressive hyperopia can be analyzed and solved in fight of the early successes with excimer laser photoablation, in my practice I am limiting RK to patients who are most likely to respond to eight incisions or less.

I feel that RK will continue to be a viable procedure for those patients who are intolerant of glasses and contact lenses, but I feel we will be limiting RK to procedures with larger clear zones and fewer incisions in the future.

DANIEL S. DURRIE, MD

Kansas City, Mo

The surgical procedure that this patient underwent in March 1983 was appropriate for that time, but if this patient presented to a radial keratotomy surgeon today, he would probably undergo eight incisions instead of 16.

The problem that this patient faces is incomplete would healing associated with what we now recognize as excessive surgery. The problem is trying to provide this patient with stable and improved vision with correction. Unfortunately, in 1992 the choices are limited and are unsatisfactory.

The first choice this patient has is to continue to change his spectacles which would be unsatisfactory for most patients, especially a busy professional. The second choice would be to wear a rigid gas permeable lens in both eyes that will decrease his vision fluctuation and provide him with a best corrected distance acuity, but will put him back into the prosthetic device he underwent the surgery to eliminate.

The third choice would be to reopen the wounds that appear to contain the largest epithelial plugs, irrigate those wounds, and then close the wounds with interrupted sutures in the 7- to 8-millimeter optical zone diameter area. This procedure will unpredictably steepen his cornea and improve his visual acuity without correction, but will only be temporary until which time the sutures have to be removed. Even with the use of topography to guide the surgeon as to which wounds to repair, the results will be unpredictable.

A fourth choice would be to undergo a hyperopic epikeratoplasty. This could certainly be performed, but because of the unpredictability of the epikeratoplasty procedure and the potential for loss of one or two lines of best corrected vision, it might not be a good option. The patient could undergo a penetrating keratoplasty using an oversized donor/recipient combination of approximately 0.25 mm which would reduce the hyperopia, but would unpredictably provide a myopic and astigmatic refractive error, bringing the patient back to where he was prior to 1983. It would stabilize his vision and that would certainly be an advantage.

Other techniques for reducing overcorrection are just not satisfactory at this time. The message that is learned from this case is that the performance of minimal surgery is usually the best approach.

PERRYS. BINDER1MD

La Jolla, Calif

Progressive hyperopia is a difficult problem. Dr Thornton had perfectly acceptable surgery, and of course, one of those unfortunate people with progressive hyperopia. Even in 1983 I probably would not have done a 16-cut radial keratotomy incision, but would have dissuaded this person to have surgery. At least in my hands the chances of getting full correction at that time were quite remote. In 1991 I probably would have done much counseling with this patient and still only have done an eight-cut radial keratotomy, maybe two depths and instigated at least one or two times after surgery the so-called Tickle procedure that has been described by Buzard and modified by myself However, this does not take care of the original problem, which is a fair degree of hyperopia, + 8.00 -3.25 × 85 OD and +6.75 -1.00 × 180 in the OS. My first choice would be rigid gas permeable daily wear contact lenses. Since the person is obviously presbyopic, he may desire to be fully corrected in the dominant eye for distance and the nondominant eye for near, Soft contact lenses, both daily and extended wear, are to be avoided after keratotomy incisions because of the danger of neovascularization.

There is no hard and fast rule in fitting these contact lenses. Finally one has to go on the pattern, comfort, and vision of the patient. On several occasions, if contact lenses have not been successful, I have sewn the wound, as described originally by Lindstrom in which the incisions are opened and a 10-0 Mersilene suture is tied in each incision under keratometric control. With the 16-cut radial keratotomy I would probably not suture all 16 bites. Because of the moderate degree of astigmatism axis 180 in this patient, I would modify the suturing technique as follows: Instead of opening up eight incisions and suturing these eight incisions, I would open up eight incisions, but in the 180-degree meridian. I would also open the incisions immediately above and below the 180 incision, and suture these at 7 mm. The purpose would be to reduce the astigmatism by clustering sutures at 180.

MILES H. FRIEDLANDER, MD

New Orleans, La

The case of an older professional with high myopia and astigmatism changing from postoperative slight undercorrection to more than 6.00 diopters hyperopia presents a significant challenge. He is now 50 years old and deserves our increasing compassionate attention since many of us in this age group are similarly developing presbyopic symptoms.

I have found that irrigating eight of the incisions and utilizing two compression sutures along eight of the incisions in an eight-incision radial keratotomy (RK) has been helpful to overcorrect the patient back to the -4.00 range. After 1 month, removal of the sutures in the steep axis has allowed the patient to return to approximately -2.00 which allows them some reading potential. The difficulty with the procedure is that it is variable and the sutures become loosened unpredictably, following the procedure, so that the patient may have irregular steepening and flattening over time.

A contact lens is a second consideration for the patient but often the patients have been contact lens failures before RK and this was the main reason for considering surgery initially. Therefore, it is difficult for them to return to contact lenses in the postoperative period.

A third procedure which we have found to be valuable is an air-lamellar keratectomy to allow the patient to utilize their own endothelium and Descemets membrane without having a transplantation rejection potential. The air-lamellar technique utilizes a 30-gauge needle with 0.1 cc of air injected into one of the incisions in the periphery of the cornea with an 8-millimeter trephine mark in place over the radial keratotomy incisions. The air injected into the stroma dissects Descemet's membrane off the back of the surface of the cornea. The recipient scarred or flat cornea is removed centrally. An 8-millimeter punched-out donor cornea, without viable endothelium is sutured in place. This technique precludes the necessity of corneal transplantation.

This technique is worthwhile for patients who have significant RK scarring or infectious processes for which a penetrating keratoplasty would be an otherwise acceptable, but more difficult, alternative.

J. JAMES ROWSEY, MD

Tampa, FIa

In our collective experience we have never seen a patient with this great a drift in the hyperopic direction. The only cases we have encountered with patients having a dramatic drift in refraction have been individuals who have undergone a redeepening procedure. Patients having a progressive shift have had, in most cases, some degree of fibrovascularization of the radial keratotomy incision. Fibrovascular ingrowth is more likely when the incisions extend all the way to the limbus. The bulk effect provided by fibrovascular tissue wtbin the incisions tends to cause a progressive shift in the hyperopic direction. Even in the absence of gross vascularization, a component of fibrous proliferation may exist within the wound, again resulting in a trend toward progression. This patient may, therefore, be best served by reopening and debriding four or eight of the incisions with placement of compression sutures. A generous amount of postoperative steroids may be helpful to avoid reproliferation of fibrovascular tissue within the incisions.

Several alternatives worthy of consideration exist, although they would be less likely to yield an immediate satisfactory solution. For example, should a diurnal curve of intraocular pressure demonstrate significant pressure variations (which may account, in part, for fluctuating acuity over the course of the day), then once a day (in the morning) topical therapy with aqueous suppressants should be considered. Betopic-S, 0.25% for example, should have no perceptible systemic symptomatology and serve to diminish the fluctuations in vision and, to a minimal degree, diminish the hyperopia.

The possibility of contact lens fit should not be overlooked, although the patient's previous history of incisions extending to the limbus would increase the risk of fibrovascular pannus proliferation within the incisions. In the event that the patient was fitted with contact lenses, the appropriate correction at the corneal plane would not only address his refractive error but also diminish his perceived presbyopia (since hyperopes accommodate less at near when wearing contact lenses than wearing glasses) and, possibly, also decrease the severity of perceived visual fluctuation. Several contact lens designs are available for post-radial keratotomy patients.

Use of the Pico-second laser is another consideration. We are presently investigating this laser for midperipheral stromal ablation in the treatment of hyperopia. However, this work is presently limited to animal models, and, while it may hold future promise for treating cases such as the one presently under discussion, human data is not yet available.

KERRY K ASSIL, MD

BRADLEY D. FOURAKER, MD

DAVID J. SCHANZLIN, MD

St Louis, Mo

Progressive hyperopia following radial keratotomy is an extremely difficult situation. All cases of progressive hyperopia that I have seen to date have had an increase in astigmatism and some degree of irregular astigmatism.

The additional fact that the patient usually, but not always, has had more than eight incisions makes treatment even more difficult.

If the patient is no longer able to be fitted with gas permeable contact lenses, then one must consider reopening the incisions, cleaning them out (removal of any inclusion cysts, epithelial debris, etc) and closure with 10-0 Mersilene suture. I would consider putting the suture at approximately one-half depth at the 5- millimeter optical zone, pulling it as tight as practical, and then attempting keratometry with the surgical keratometer. If it is not flattened satisfactorily by keratometry, then placing a second Mersilene buried suture at the 7-millimeter optical zone must be considered.

Correctly placing the sutures is not an easy task and even a correct placement does not guarantee a reasonable result.

We can only hope that the future holds the development of a laser procedure which will allow us to "reconstruct" the cornea in these difficult progressive hyperopia cases.

DAVID B. DAVIS H, MD

Hayward, Calif

Progressive hyperopia and its associated astigmatism were initially reported by Michael Dietz, MD. Analysis of causation was mentioned 2 years ago by Maurice John, MD, who suggested that possibly rubbing or massaging the eyes was somehow related to this progression.

I have seen progressive hyperopia as a result of chronic eye rubbing (usually related to a mild eye allergy) and from the postoperative use of contact lenses. John subsequently reported a bilateral radial keratotomy (RK) patient with unilateral progressive hyperopia due to the pressure of sleeping on her stomach with the involved eye buried in the pillow. Ron Schachar, MD, has reported several cases of progressive hyperopia that were reversed by the use of ocular lubricants at bedtime.

As far as treatment is concerned, I would explore the patient's desire or lack of desire to wear glasses or contact lenses for the correction of this refractive error. If the patient is adamantly opposed to glasses or contacts, I would perform opening, debridement, and suturing of the RK incisions.

DENNIS D. SHEPARD, MD

Santa Maria, Calif

Why the overcorrection did not occur early and showed up later, I cannot say, but this is apparently that phenomenon of the "drift toward hyperopia." The present situation is that of a large overcorrection in the right eye with a lot of positive cylinder in the 175-degree axis and a large overcorrection in the left eye with a small amount of cylinder in the 90-degree axis. For the right eye, I would open the radial cuts closest to the 85-degree meridian and suture them back closed quite tightly with 10-0 nylon with the two legs of the X based on 5- and 7-millimeter optical zones so that the average effect was at 6mm. This will cause steepening in the opposite meridian from the already very steep cornea at 175° and could yield a very good result. If the left eye is well-healed and the incisions are tight and there is no in-wound epithelialization, I would do a hexagonal keratotomy on this eye. It is essential that this eye be totally healed or the hexagonal keratotomy could yield extremely poor results. I think both of these would be effective in reducing or significantly eliminating this problem.

J. CHARLES CASEBEER, MD

Flagstaff Ariz

The 42-year-old professional man presented is a classical example of severe progressive hyperopia in a presbyopic male. I have seen several similar patients although this case is more severe than the average.

The initial approach is to try spectacles or in some patients contact lenses with monovision approach or the use of reading glasses, as needed. If this fails, I have used a suture repair technique where the incisions are opened with removal of the epithelial facette and a running purse string or interrupted suture technique is used to close the incisions at approximately a 7-millimeter optical zone. In a patient with such severe overcorrection I would recommend consideration of a purse string suture at a 7-millimeter optical zone in combination with multiple interrupted single or ? sutures. Each single or ? suture could be used to compress two incisions and this would, therefore, require eight interrupted or ? sutures at approximately 7-millimeter optical zone in combination with the running purse string suture.

It is possible to correct up to 2.00 to 3.00 diopters of hyperopia with these techniques. This patient may be outside the range of suture correction. This, however, would be my first attempt at repair.

The unexpected progressive hyperopia that occurs in a significant number of patients is to date unpredictable in advance of surgery and remains one of the most distressing complications of radial keratotomy.

RICHARD L. LINDSTROM, MD

Minneapolis, Minn

As one follows the patient's refractive error it goes from OD -1.00 -0.50 X 50 and OS piano at 3 months postop to OD +5.50 -3.00 X 55 and OS + 4.00 - 1.00 X 80 at 36 months postoperative.

Thus, each cornea has steepened by about 4.00 diopters. Each cornea has developed significant astigmatism, and the curvatures are changing throughout the day (ie, fluctuating vision). Such flexible corneas suggest very little scar tissue has developed to heal the incisions, (ie, epithelium has filled in the incisions). The corneal flattening suggests that his IOP is lower than in the early postoperative period, since IOP helps push the keratectomized cornea into its new shape.

Theoretically, one should scrape out the epithelium in each incision and hope that a fresh healing wound would bring more scarring, a stronger cornea, and less fluctuating vision. Practically speaking, I would try fitting him with rigid gas permeable contact lenses, with a very high DK value, to oxygenate all those extra epithelial cells.

DAVID MILLER, MD

Boston, Mass

Overcorrected radial keratotomy patients present the most difficult challenge that a refractive surgeon encounters in his practice. A patient who presents with the problem of undercorrection is generally easy to manage. The problem of overcorrection, however, has very few solutions. I have tried suturing these wounds with purse string sutures and have had mixed results. The technique involves opening up eight of the previous radial incisions at an 8.00-milhmeter optic zone and passing a 9 or 10-0 prolene or Mersilene suture through the mid stroma, entering and exiting through each adjacent radial incision. The knot is then buried at the first entry site. The problem is one of suture tightening. Even with the use of a surgical keratometer, the result is impossible to quantitate. My goal has been to err on the side of overcorrecting the hyperopia and leaving the patient with a myopic correction. This requires an adequate tightening of the knot which is facilitated by a small paracentesis while adjusting the suture.

Another complication that I see using this procedure is a stromal keratitis around the suture at each of the radial incision sites. This usually responds to topic steroids but on two occasions, the suture has had to be removed. Both of these cases were with prolene.

The best procedure is homoplastic lamellar keratoplasty. I have published my results on several cases and find this the most reliable method of correction.

I would first encourage the patient to wear contact lenses, if at all possible. If not, then I would begin by putting in a purse string suture, telling the patient that this might not handle his or her problem. I tell the patient that this cannot be quantitated but it does give him a chance for correction with an office surgery type of environment. This would then be followed later by a homoplastic lamellar keratoplasty if the purse string suture did not work. I must stress that the best method of treatment is prevention and encourage the use of four incisions whenever possible with the addition of four additional incisions or back-cutting, whichever is indicated on that particular patient. Hyperopia in my hands is the worst complication that is encountered.

RICHARD A. VILLASENOR, MD

Los Angeles, Calif

10.3928/1081-597X-19920701-16

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