Journal of Refractive Surgery

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Surgical Techniques 

Surgical Correction of Hyperopia Following Radial Keratotomy

Richard E Damiano, MD, FACS; S Lance Forstot, MD, FACS; Debra K Dukes, COT

Abstract

ABSTRACT

Background: No effective treatment for hyperopia following radial keratotomy has been described. A new surgical technique of two purse-string intrastromal sutures was investigated for correction of this hyperopia.

Methods: Eighteen radial keratotomy patients who were unhappy with uncorrected vision and who were unsatisfied with contact lens or spectacle correction, after informed consent, underwent corneal suturing. The 19 hyperopic eyes included 5 original overcorrections, 5 overcorrections after reoperation, and 9 progressive hyperopes. The refractive error ranged from +1.25 to +5.75 diopters spherical equivalent (mean +3.47 D). Presuturing uncorrected visual acuity ranged from 20/50 to 20/400 with 11 eyes (58%) 20/100 or worse.

Results: The follow up after double purse-string suturing averaged 24 months (range, 12 to 47 months). All patients had follow up of at least 1 year; 14 patients (74%) had follow up of 2 years or more. The change in refractive spherical equivalent following surgery averaged -3.30 D (range, -1.00 to -7.50 D). The steepening in average keratometry was 4.10 D (range, 1.00 to 8.00 D). The refraction after suturing averaged -1.12 D (range, +2.50 to -3.50 D). Uncorrected visual acuity after suturing was 20/40 or better in 14 eyes (74%), and 20/50 to 20/80 in 5 eyes (36%). There were no significant intraoperative, early or late postoperative complications. Seventeen eyes were either the same or gained 1 line of acuity; 2 eyes gained 2 lines of acuity; no eyes lost any lines of refractive Snellen acuity.

Conclusions: The placement of two purse-string intrastromal sutures appears to provide significant steepening of the central cornea following excessive flattening after radial keratotomy. The steepening effect appears to remain stable with greater than 1-year follow up. This surgical technique offers an alternative to symptomatic hyperopic postradial keratotomy patients who cannot be corrected with spectacles or contact lenses. (Refract Corneal Surg 1992;8:75-79.)

Abstract

ABSTRACT

Background: No effective treatment for hyperopia following radial keratotomy has been described. A new surgical technique of two purse-string intrastromal sutures was investigated for correction of this hyperopia.

Methods: Eighteen radial keratotomy patients who were unhappy with uncorrected vision and who were unsatisfied with contact lens or spectacle correction, after informed consent, underwent corneal suturing. The 19 hyperopic eyes included 5 original overcorrections, 5 overcorrections after reoperation, and 9 progressive hyperopes. The refractive error ranged from +1.25 to +5.75 diopters spherical equivalent (mean +3.47 D). Presuturing uncorrected visual acuity ranged from 20/50 to 20/400 with 11 eyes (58%) 20/100 or worse.

Results: The follow up after double purse-string suturing averaged 24 months (range, 12 to 47 months). All patients had follow up of at least 1 year; 14 patients (74%) had follow up of 2 years or more. The change in refractive spherical equivalent following surgery averaged -3.30 D (range, -1.00 to -7.50 D). The steepening in average keratometry was 4.10 D (range, 1.00 to 8.00 D). The refraction after suturing averaged -1.12 D (range, +2.50 to -3.50 D). Uncorrected visual acuity after suturing was 20/40 or better in 14 eyes (74%), and 20/50 to 20/80 in 5 eyes (36%). There were no significant intraoperative, early or late postoperative complications. Seventeen eyes were either the same or gained 1 line of acuity; 2 eyes gained 2 lines of acuity; no eyes lost any lines of refractive Snellen acuity.

Conclusions: The placement of two purse-string intrastromal sutures appears to provide significant steepening of the central cornea following excessive flattening after radial keratotomy. The steepening effect appears to remain stable with greater than 1-year follow up. This surgical technique offers an alternative to symptomatic hyperopic postradial keratotomy patients who cannot be corrected with spectacles or contact lenses. (Refract Corneal Surg 1992;8:75-79.)

Hyperopia can be a disturbing optical complication of radial keratotomy.1 No effective treatment for this condition has been found. A singlepurse-string intrastromal suture has been recommended for surgical correction but no data exist on the results of this procedure.2 Other procedures, including epikeratophakia, keratomileusis, and hexagonal keratotomy, have all been tried for treating hyperopia but have not been reported for hyperopia after radial keratotomy.

This retrospective study analyzes consecutive radial keratotomy patients who underwent correction of their hyperopia by a single surgical technique of double purse-string intrastromal sutures.

PATIENTS AND METHODS

Eighteen patients with hyperopia fouowing radial keratotomy who were unhappy with their uncorrected vision and who were not satisfied with contact lens correction underwent corneal suturing at the Colorado Radial Keratotomy Center between June 1986 and March 1989. There were 11 males and 7 females. Their ages ranged from 27 to 68 years, with a mean of 39 years. The diagnoses of the sutured patients included 5 original overcorrections, 5 overcorrections after reoperation, and 9 cases of progressive hyperopia. The patients had from 8 to 32 radial incisions. Eight of the patients had had horizontal astigmatic keratotomy incisions.

Figure 1 : Double purse-string, continuous suture following radial keratotomy.Figure 2: Six months postoperative keratoscope.

Figure 1 : Double purse-string, continuous suture following radial keratotomy.

Figure 2: Six months postoperative keratoscope.

All procedures were done by one surgeon (R.E.D.). Ophthalmologic and medical histories were obtained by an ophthalmic technician who also performed best corrected and uncorrected visual acuity testing. The Snellen chart at a mirrored, 20-foot distance in a darkened room was used for all preoperative and postoperative visual acuity measurements. Preoperative manifest refractions using a fogging technique were done by the surgeon. The patients also underwent a slit-lamp examination, automated keratometry, and applanation tonometry. Optical pachymetry was performed by the surgeon with Mashima-Hedsbys modification. Each patient received a thorough explanation of the procedure, including risks and complications. Before signing the informed consent, they were also told that the surgery was investigational and that, to his knowledge, no other surgeons were performing this surgery.

OPERATIVE PROCEDURE

Surgery was performed on an outpatient basis using topical anesthesia with proparacaine hydrochloride 0.5%. Under an operating microscope, the optical center was marked in a fashion similar to that used in the Prospective Evaluation of Radial Keratotomy (PERK) study.3 The optical zones of 5 mm and 7 mm were marked. The KOI adjustable reverse cutting micrometer diamond knife was used to open all the radial incisions from the 8-millimeter to the 4-millimeter optical zone. The blade of the incision was set at 75% of the central optical pachymetry reading. A 10-0 Mersilene suture on a TG140-6 needle was passed circumferentially for 360° coincident to the 7-millimeter optical zone starting at the 11 o'clock position, passing it to V2 stromal thickness, and exiting through the previously-opened radial incision. Starting at the 1 o'clock position coincident to the 5-millimeter optical zone, a second suture was passed circumferentially. A paracentesis was made at the temporal limbus using a #75 microsharp blade. The suture at the 7millimeter optical zone was tightened, ensuring prominent steepening of the central cornea, and tied with a surgeon's knot. The suture at the 5millimeter optical zone was then tied in a similar manner. The suture ends were cut and the knots buried in the stroma (Fig 1). The steepening produced could not be measured accurately with either a hand-held keratoscope or surgical keratometer. Topical, unpreserved chloramphenicol was used as the surface irrigant during these cases.

Postoperatively, tobramycin and homatropine (2% drops) were applied. The eye was lightly patched. The patient was discharged with a prescription for oral analgesic medication.

Postoperative examinations were done on day 1, week 1, month 1 (±1 week), month 3 (±1 month), month 6 (±2 months), 1 year (±3 months), month 18 ( ± 3 months), and month 24 ( ± 4 months). Tobrex and FML drops were administered 4 times daily for 1 to 2 weeks postoperatively and then tapered.

RESULTS

Nineteen eyes of 18 radial keratotomy patients were studied retrospectively (Table). Mean preoperative spherical equivalent was +3.47 diopters (range, + 1.25 to + 5.75 D). Mean preoperative keratometry reading was 38.50 D (range, 28.00 to 41.50 D). Average preoperative cylinder was 2.75 D (range, 1.50 to 5.00 D). Presuturing uncorrected visual acuity ranged from 20/50 to 20/400. Eleven eyes (58%) had uncorrected acuity of 20/100 or worse. Eight eyes (42%) were between 20/50 and 20/80. The time from radial keratotomy to double purse-string suturing averaged 25 months (range, 8 to 51 months).

Table

TableVisual Acuity, Refraction (D), and Keratometry on Eyes With Double Purse-String Intrastromal Suturing for Hyperopia After Radial Keratotomy

Table

Visual Acuity, Refraction (D), and Keratometry on Eyes With Double Purse-String Intrastromal Suturing for Hyperopia After Radial Keratotomy

Table

TableVisual Acuity, Refraction (D), and Keratometry on Eyes With Double Purse-String Intrastromal Suturing for Hyperopia After Radial Keratotomy

Table

Visual Acuity, Refraction (D), and Keratometry on Eyes With Double Purse-String Intrastromal Suturing for Hyperopia After Radial Keratotomy

The time after double purse-string suturing averaged 24 months (range, 12 to 47 months). All patients had a follow up of 1 year. Fourteen patients (74%) had a follow up of 2 years or more.

The change in refraction spherical equivalent following double purse-string sutures averaged -3.30 D (range, - 1.00 to - 7.50 D). The steepening in average keratometry was 4.10 D (range, 1.00 to 8.00 D). The refraction postsuturing averaged - 1.12 D (range, 2.50 to -3.50 D). The average cylinder postsuturing was 2.50 D (range, 1.00 to 4.50 D).

Postsuturing uncorrected visual acuity was 20/40 or better in 14 eyes (74%) and 20/50 to 20/80 in 5 eyes (36%). Postsuturing best refractive visual acuity was the same or one line better in 17 eyes and improved by two lines in two eyes.

Complications of Double Purse-String Intrastromal-Sutures

There were no intraoperative complications. Light sensitivity and discomfort were common immediately postoperatively but these symptoms did not persist beyond 1 month. There were no significant, adverse reactions to the Mersilene sutures. Early on, in three cases, vascularization to the suture knots did occur but this vascularization regressed with short-term topical steroids. Only one patient had to have one of the Mersilene sutures removed at 6 months because of erosion of a knot. The keratometry reading and refraction did not change significantly following removal. However, this eye had the least amount of surgical steepening (1.00 D).

Irregular astigmatism may be a complication of any corneal refractive surgery. It was not clinically significant after 3 months in any of these 19 eyes (Fig 2).

DISCUSSION

Overcorrection, or hyperopia, is one of the optical complications following radial keratotomy.1 With significant postoperative hyperopia defined as greater than 1.00 D, early metal blade series analyzed at 1 year had overcorrection rates from 4% to 24%?7 In their diamond blade radial keratotomy series, Dietz et al reported 13% were overcorrected at 1 year.8 In the PERK study, 10% of patients were overcorrected by greater than 1.00 D at 1 year.9 The PERK study employed an 8-incision radial keratotomy; however, even 4-incision radial keratotomy studies have had overcorrection with rates of 3.5%10 and 6.5%.11

Hyperopia can also be induced following a repeat operation for radial keratotomy. There are few reports on the results of repeat radial keratotomy. The PERK study reported eight additional incisions in 59 patients; two patients (3%) were overcorrected by more than 1.00 D.12

A third mechanism for hyperopia following radial keratotomy is that which occurs progressively after surgery. Dietz et al, in their metal blade series, reported 30.9% hyperopia at 1 year; 35% at 2 years; and 38.7% at 4 years.13 In their diamond blade series, Dietz and colleagues reported 20.8% hyperopia at 1 year and 27.3% at 2 years.13

In the PERK study, overcorrection increased from 10% at 1 year9 to 16% at 3 years,14 and 20% at 5 years.15

Clearly, hyperopia after radial keratotomy can be a significant problem following the initial procedure, following a secondary operation, or as a result of progressive corneal flattening from the original surgery. Hofmann reported the use of a continuous, purse-string suture of Mersilene as management for overcorrection.16 The single, continuous, pursestring suture was associated with two drawbacks: there was a loss of effect with time and two of the seven reported cases developed a persistent, noninfectious keratitis requiring removal of the continuous suture. Lindquist et al have reported the use of interrupted sutures to close either 4- or 8-incision radial keratotomy incisions to decrease hyperopia.17·18 With 4- to 26-month follow up in 4-incision radial keratotomies, there was a steepening of 1.60 D. With 3- to 12-month follow up in 8-incision radial keratotomies, there was a 1.46-diopter central corneal steepening. The authors suggest that the interrupted suture technique has the advantage that selective sutures could be removed postoperatively to modify induced or residual astigmatism.

Initially, this surgeon tried a single, continuous, purse-string suture but found the effect rapidly degraded and this technique was abandoned. It was felt that possibly two purse-string sutures would allow a more permanent effect even if there was some degradation of the steepening effect. Therefore, the technique of placing two continuous, pursestring sutures was tried; one suture at a 5milli meter optical zone and one suture at a 7millimeter optical zone. There was an average steepening in keratometry of 4.10 D (range, 1.00 to 8.00 D) with a change in refraction of -3.30 D (range, - 1.00 to - 7.50 D). This led to uncorrected visual acuity postsuturing of 20/40 or better in 14 eyes and 20/50 to 20/80 in 5 eyes. There were no significant complications intraoperatively, in the immediate postoperative period, or in the late postoperative period.

The placement of two continuous, purse-string sutures of Mersilene appears to provide significant steepening of the central cornea following the flattening which has occurred from radial keratotomy. This study, with greater than 1 year follow up, indicates that the steepening effect appears to remain stable. It offers a surgical alternative for those patients with symptomatic hyperopia post radial keratotomy who cannot be corrected with spectacles or contact lenses.

REFERENCES

1. Binder PS. Optical problems following radial keratotomy. Ophthalmology. 1986;93:739-745.

2. Starling J, Hofmann R. A new surgical technique for the correction of hyperopia after radial keratotomy: an experimental model. Journal of Refractive Surgery. 1986;2:96-98.

3. Neumann AC, Osher RH, Fenzl RE. Radial keratotomy: a comprehensive evaluation. Doc Ophthalmol. 1984;56:275301.

4. Kremer FB, Marks RG. Radial keratotomy: prospective evaluation of safety and efficacy. Ophthalmic Surg. 1983;14:925930.

5. Sawelson H, Marks RG. Two-year results of radial keratotomy. Arch Ophthalmol. 1985;103:505-510.

6. Arrowsmith PN, Marks RG. Visual, refractive and keratometric results of radial keratotomy: one-year follow-up. Arch Ophthalmol. 1984;102:1612-1617.

7. Dietz MR, Sanders DR, Marks RG. Radial keratotomy: an overview of the Kansas City study. Ophthalmology. 1984;91:467-478.

8. Dietz MR, Sanders DR, Raanen MG. A consecutive series (1982-1985) of radial keratotomies performed with the diamond blade. Am J Ophthalmol. 1987;103:417-422.

9. Waring GO, Lynn MJ, Gelender H, et al. Results of the prospective evaluation of radial keratotomy (PERK) study one year after surgery. Ophthalmology. 1985;92:177-198.

10. SaIz JJ, Villaseñor RA, Elander R, et al. Four-incision radial keratotomy for low to moderate myopia. Ophthalmology. 1986;93:727-738.

11. Spigelman AV, Williams PA, Nichols, et al. Four-incision radial keratotomy. J Cataract Refract Surg. 1988;14:125-128.

12. Cowden JW, Lynn MJ, Waring GO, et al. Repeated radial keratotomy in the prospective evaluation of radial keratotomy study. Am J Ophthalmol. 1987;103:423-431.

13. Dietz MR, Sanders DR, Reanan MG. Progressive hyperopia in radial keratotomy. Long-term follow-up of diamond knife and metal blade series. Ophthalmology. 1986;93:1284-1289.

14. Waring GO, Lynn MJ, Culbertson W, et al. Three-year results of the prospective evaluation of radial keratotomy (PERK) study. Ophthalmology. 1987;94:1339-1354.

15. Waring GO, Lynn MJ, Fielding B. Five-year results of the prospective evaluation of radial keratotomy (PERK) study, abstract. Ophthalmology. 1990;97:(suppl):127.

16. Hofmann RF. Reoperations after radial keratotomy and astigmatic keratotomy. Journal of Refractive Surgery. 1987;3:119-128.

17. Lindquist TD, Rubenstein, JB, Lindstrom RL. Correction of hyperopia following radial keratotomy: quantification in human cadaver eyes. Ophthalmic Surg. 1987;18:432-437.

18. Lindquist TD, Williams PA1 Lindstrom RL. Surgical treatment of over-correction following radial keratotomy: evaluation of clinical effectiveness. Ophthalmic Surg. 1991;22:1215.

Table

Visual Acuity, Refraction (D), and Keratometry on Eyes With Double Purse-String Intrastromal Suturing for Hyperopia After Radial Keratotomy

Table

Visual Acuity, Refraction (D), and Keratometry on Eyes With Double Purse-String Intrastromal Suturing for Hyperopia After Radial Keratotomy

10.3928/1081-597X-19920101-15

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