Epikeratoplasty is a form of lamellar keratoplasty based on principles of the Barraquer refractive procedures but simplified to eliminate the use of a microkeratome.1"2 A donor corneal tissue lenticule, preshaped by cryolathing, is sutured centrally, after epithelium removal, over Bowman's membrane on the cornea. Both the surgical technique and postoperative management could be further simplified if suture use was successfully eliminated.
Sutures are time-consuming to position at surgery and can result in lenticule damage and unequal tension at the wound edge. Postoperatively, suture management is a major determinant in the primary healing process of epikeratoplasty. Overly tight sutures can result in refractive undercorrection and astigmatism in specific meridians. Loose sutures cancause lid irritation, local corneal necrosis, infiltrates, vascularization, and rarely, frank bacterial keratitis. For the pediatric age group, suture removal necessitates a second exposure to the risks of general anesthesia. Morbidity for adults is increased, as suture removal at the slit lamp creates anxiety for the patient and can carry the risk of localized epithelial abrasion with concomitant bacterial contamination.3-4
In order to reduce the hazards from sutures, attempts have been made to create a technique for sutureless epikeratoplasty. Grabner used no sutures in both myopic and aphakic epikeratoplasty, after first reducing the number of sutures and then abandoning the use of fibrin glue. He does not mention varying lenticule size, but did eliminate the annular keratotomy with effective results.5"7 Use of a biological adhesive has been investigated in vitro and with rabbits, as well as gluing with autologous cryoprecipitate, in an attempt to achieve sutureless epikeratoplasty.8"10 Carbon dioxide laser in wound sealing and epikeratophakia has been investigated.11 Detailed results from a no-suture technique for epikeratoplasty patients have not been previously reported. A study was undertaken to evaluate the outcome of a no-suture technique, utilizing an oversized lenticule, for aphakic epikeratoplasty in a series of 27 consecutive eyes operated on by one surgeon. The technique, as developed by the author, is a modification of the conventional surgical procedure which utilizes sutures.
This article describes the refractive and visual results, as well as the complications when using a no-suture technique for aphakic epikeratoplasty.
PATIENTS AND METHODS
Twenty-seven patients underwent epikeratoplasty for correction of monocular aphakia between May 1988 and January 1989. In an attempt to avoid surgeon bias in applying the no-suture technique, each patient was included on a consecutive basis with no exceptions, assuming the patient met the standard criteria for a conventional epikeratoplasty procedure. The 27 cases of consecutive, no-suture epikeratoplasty were then analyzed retrospectively by chart review.
The mean age of patients in the study was 15.3 years (SD ± 14.8), with 12 patients (44%) under age 10 years, 13 (48%) age 10 to 40 years, and only 2 (8%) above age 40 years. There were 19 (70%) male patients and 8 (30%) female patients. Young patients, age 2 to 9 years, were accepted for surgery despite moderate to severe preoperative amblyopia, manifestation of frank strabismus, high corneal astigmatism, and scars, because all other alternative modalities of treatment had been exhausted. In these patients, compliance with patching procedures for amblyopia had been infrequent and in many cases nonexistent. Attempts at contact lens correction had been abandoned after an unacceptably high rate of lens loss. Compounding already existing amblyopia in these cases was a 6-week surgical delay necessary for ordering and shipping of the lenticule outside the United States. One patient, a complete contact lens failure, had quiescent, recurrent, vernal catarrh but underwent the procedure because the condition of the anterior segment combined with his age precluded use of an intraocular lens.
All of the lenticule tissue used in this study was commercially prepared (Allergan Medical Optics, Irvine, Calif); the procedure for preparation of these lenticules has been previously described.12'15 The lenticules were received in a sealed vial, and all were used by the recommended deadline of within 2 months from the date of manufacture. One lenticule had been temporarily stored in a corneal storage medium, K-SoI, which was contaminated by Propionibacteria and was applied to a patient in this study before the manufacturer's notification.16
All lenticules were specially ordered to be 9 mm in diameter, a 0.5-mïllimeter oversize compared to the standard 8.5-millimeter lenticule used in aphakic patients for epikeratoplasty. There was no other variation in lens design from that used in preparing a standard lenticule for the conventional epikeratoplasty procedure. Three lenticules of standard 8.5millimeter diameter were used for study patients when the special order size was inadvertently overlooked by the manufacturer.
The patient's visual axis was marked using a Sinsky hook by splitting the horizontal and vertical measurements of the corneal diameter. A 7.0millimeter Hessburg-Barron trephine was centered over the visual axis mark, applied by suction, and a 0.35-millimeter depth trephine cut created. Since topical cocaine is not approved for use in this institution, a microsponge disc soaked in absolute alcohol and squeezed until just damp was applied to the central cornea for 20 seconds. A #64 Bard Parker blade and angled tying forceps was then used to remove the epithelium in sheet-like fashion. Copious irrigation and aspiration were performed to meticulously clear all debris. The Suarez spreader was used at the depth of the trephine cut to split the recipient corneal stroma for a full 1 to 1.5 mm peripherally, creating a 360° stromal lamellar pocket.
The lenticule was rehydrated for 20 minutes in the standard solution of balanced salt with 100 µg/mL of gentamicin. After irrigation, the lenticule was centered on the cornea and the edges tucked evenly into the lamellar pocket for 360° using angled tying forceps and a Suarez spreader. Extreme care was taken to ensure centration of the lenticule with an equal 1-millimeter edge buried symmetrically. In the three patients with undersized lenticules of 8.5 mm, the graft/bed disparity was reduced; this resulted in failure of the surgical tucking procedure in one patient, who required placement of interrupted sutures at the time of surgery.
In all cases, a bandage soft contact lens (Hydrocurve II, 55% H2O content) was applied and care was taken to seat the lens firmly over the central cornea. This helped to splint and secure the lenticule in place while protecting it from lid action. Gentamicin and dexamethasone were injected subconjunctivally at the end of the procedure, with application of gentamicin and scopolamine 2% drops. The eye was pressure patched and a protective shield applied. The patch was removed permanently on the 1st postoperative day, with the shield maintained until complete reepithelization.
The eyes were examined postoperatively every 24 hours until reepithelialization of the lenticule was complete, at which time the bandage lens was removed (routinely at 5 days). Cycloplegic and antibiotic drops were given twice daily until reepithelialization; then sulfacetamide 10% drops were administered for 2 weeks. Daily examinations were possible because of the unique in-patient hospital setting for this study. An out-patient setting would require only routine follow up, once initial reepithelization was complete.
Twenty-seven consecutive patients, ranging in age from 2 years to 66 years, received aphakic epikeratoplasty using a no-suture technique. Average follow up from the date of surgery for the 27 cases was 14 ± 3 months (mean ± SD) with one patient lost to follow up after 3 months. Twenty-four of the eyes received an oversize aphakic lenticule of 9 mm while three received a standard size 8.5-millimeter lenticule. The three standard size 8.5-millimeter lenticules were used to avoid unnecessary delay for the patients, but the reduced size resulted in failure of the no-suture surgical technique in one case, requiring that interrupted sutures be placed at surgery to secure the lenticule. All oversize 9-millimeter lenticules and two of the 8.5-millimeter lenticules were successfully placed at surgery using a no-suture technique. One 8-year-old patient had his epikeratoplasty coupled with cataract removal to expedite visual recovery. Excluding the data from that patient with an undersized lenticule who required suturing at surgery, results show 24 of 26 (92.3%) patients healed without sutures.
Figure 1: Illustrates the postoperative visual results after nosuture epikeratoplasty, demonstrating visual acuity was returned to best corrected preoperative acuity, or tested better than postoperative due to improved patient cooperation, in 92.3% (24/26) of the eyes.
In order to assess visual outcomes more meaningfully, the patients were separated into three general age groups.
The pediatric group includes 12 patients, from age 2 to 9 years (5.1 ± 2.18 years), 11 (92%) of whom had profound amblyopia preoperatively and 9 (75%) frank strabismus. Two (16%) had significant corneal scarring greater than 3 mm in length, with corneal flattening in one and 5.00 diopters of irregular astigmatism in the other. In all, 8 (66%) patients in the pediatric group had developed cataracts secondary to trauma and 4 (33%) had congenital cataracts prior to surgical removal. The average time between cataract removal and epikeratoplasty was 18 months, with a range from 4 to 29 months, excluding the one case in which epikeratoplasty was done simultaneously with cataract extraction. Figure 1 and the Table show the visual and refractive results. Only three patients cooperated dependably for preoperative visual acuities. In order to avoid bias from the presence of sutures, the 2-year-old patient (no. 3) who had lenticule edge dislocation with suturing was excluded from the overall visual acuity tabulation. This patient, who had prior congenital cataract, improved from no fixation preoperatively to 1.5/30 postoperatively.
Spectacle corrected visual acuity improved in 82% (9/11) of the tabulated patients, with the four patients having had previous congenital cataracts showing minimal improvement. Average improvement in best corrected acuity was two Snellen lines at last followup visit, with one patient improved to 20/40, and the 8-year-old with combined procedure of cataract removal and epikeratoplasty to 20/30. A negative factor for improvement in acuity postoperatively for patients was their relative noncompliance with amblyopia therapy and only intermittent spectacle wear.
Refractive evaluation showed the mean sphere significantly decreased from + 14.50 D ± 2.20 D preoperatively to - 1.40 ± 2.60 D 6 months postoperatively, a decrease of 15.90 D. At 6 months, 55% (6/11) were within ± 1.00 D of emmetropia, and 27% were within ± 3.00 D of emmetropia (3/11), leaving 18% more than 3.00 D off the target of emmetropia. The maximum deviations were an overcorrection of 4.50 D and an undercorrection of 2.50 D (expressed as spherical equivalents). High astigmatism was present preoperatively in one patient, and this same 5.00 D astigmatism was present postoperatively, both by refraction and keratometry. The remaining patients in the pediatric group had an average refractive cylinder preoperatively of + 1.22 ± 0.80 D, with an average of +1.90 ± 1.40 D present postoperatively. As expected, average keratometry steepened from 43.00 D preoperatively to 58.30 D postoperatively, an increase of 15.30 D. The mean refraction preoperatively was + 14.40 + 1.34 × an average of 89° and postoperatively was -1.00 + 1.80 × an average of 83°.
Young Age Group
The young age group included 13 patients in the teen to adult age, ranging from 10 to 33 years (average, 18.2 ± 7.2 years). Best spectacle corrected visual acuity for the young group preoperatively ranged from 20/20 to 20/70 with an average of 20/40. Three patients from this group suffered partial lenticule edge dislocation, all with 9-millimeter lenticles, but only one required sutures, for which his 20/25 visual acuity results were excluded from the general tabulation in order to show no-suture refractive results more clearly. Some patients had conditions limiting their final best corrected visual acuity, including mild posterior capsular fibrosis, mild macular damage secondary to old trauma, and partial amblyopia. Two eyes had an 8.5-millimeter lenticule used without dislocation for the no-suture technique, with no effect on refractive result being noted and both are included in the final tabulation. Average follow up was 13 ± 2 months. Figure 1 and the Table show the visual and refractive results.
Uncorrected visual acuity returned to preoperative levels or better in 100% of the young patients. Best spectacle corrected visual acuity returned to preoperative levels or better in 10 (83.3%) of the patients. Two eyes (16.6%) decreased best corrected visual acuity postoperatively by two lines. The one lost vision secondary to a corneal epithelial haze that developed after recurrent vernal catarrah, and one developed foveal changes after a recurrent uveitis, which was unrelated to the epikeratoplasty procedure.
The mean sphere for eyes in the young group decreased from + 10.60 ± 2.30 D to - 1.71 ± 2.30 D after 6 months, a decrease of 12.30 D. At 6 months, 50% of the eyes were within ± 1.00 D of emmetropia, 25% within ±2.00 D, and 8% within ± 3.00 D. The maximum deviations were an overcorrection of 6.00 D and an undercorrection of 0.75 D (expressed as spherical equivalents). Average refractive cylinder preoperatively was +0.71 ± 0.66 D and postoperatively + 1.60 ± 1.60 D. Average keratometry steepened from 43.40 D preoperatively to 54.40 D postoperatively, an increase of 11.00 D. The average overall refraction preoperatively was + 10.50 + 0.71 × an average of 88° and postoperatively - 2.73 + 1.20 × an average of 85°. One eye developed high astigmatism of 6.00 D related to an epithelial interface cyst. This same eye had a lenticule edge dislocation reposited, but the cyst occurred 2 months later, 90° away from the area of repositing. Spectacle corrected visual acuity remained at 20/50, equal to the best preoperative acuity.
The third, older age group, was comprised of two patients, one 66 and one 55 years of age, with results reported individually. The 66-year-old female patient suffered a lenticule-stromal interface infiltrate at 2 weeks postoperatively, which may have been related to the K-sol lenticule storage solution contaminated with Propionibacteria. The infiltrate cleared with antibiotic treatment, but no organism was identified. Earlier, on the 2nd postoperative day, the same patient had an unrelated, 20-degree sector dislocation of the lenticule edge, which was successfully treated with iris spatula repositioning at the slit lamp. The 55-year-old male patient had corneal opacity secondary to climatic droplet keratopathy, reducing best correctable vision to 20/40.
At 1 month postoperative, both patients achieved visual acuity equal to their best spectacle corrected visual acuity of 20/40. The patient with corneal opacity achieved 20/30 with pinhole correction but was lost to follow up at 3 months. The other patient, with a treated interface infiltrate, had her visual acuity improved to 20/30 with a correction of + 2.25 + 2.00 × 120° at 14 months. This was a one-line improvement in spectacle corrected visual acuity from her preoperative testing level.
No eye required lenticule removal. Five eyes had early sector lenticule edge dislocation from the lamellar pocket; three of the sector dislocations were reposited at the slit lamp using an iris spatula. The dislocations were discovered at the slit lamp with therapeutic contact lens in position. The dislocations occurred before epithelium had covered the sectors of the lenticule-pocket interface involved. No edge dislocation included more than 3 clock hours of arc in area. The sutures were removed at 1 month. Two lenticules required focal suturing with two and four sutures respectively.
For all three groups, the combined lenticule edge dislocation rate was 19%. Of the five dislocations, three (60%) were reposited at the slit lamp, while the other two (40%) required sutures. Only one dislocation occurred in the pediatric group, and one in the older age group. Three occurred in the young age group. Four of the five lenticule edge dislocations were noted on the 2nd postoperative day and the fifth occurred at the 4th postoperative day.
Rapid reepithialization of the lenticule took place in most patients, being complete by the 5th postoperative day in all but five patients. Of these five, four were healed by 9 to 11 days, and two had defects occurring in relation to their partial lenticule edge dislocation. One patient with a true, postoperative persistent epithelial defect had chrome vernal catarrh, and had received epikeratoplasty by rio-suture technique in hopes that the technique would minimize his expected reepithelialrzation problems. Final healing of this patient's epithelium did not take place until 22 days postoperatively, after 2 weeks of pressure patching without a bandage contact lens.
One 66-year-old patient developed a lenticule interface corneal stromal infiltrate. The lenticule manufacturer (AMO) notified us of the discovery that this patient's lenticule had been temporarily stored in a solution, K-SoI, which was contaminated by the anaerobe Propionibacteria.16,17 The infiltrate occurred at 2 weeks postoperatively, was treated with frequent topical antibiotics, and resolved over 3 weeks. A second lenticule, the only other one identified to have been stored in the manufacturer's contaminated storage solution, was applied by conventional technique by another surgeon; subsequently, it failed, with melting and removal at 6 weeks.
One 7-year-old patient with a well healed epikeratoplasty suffered mechanical trauma at 6 months postoperatively, resulting in peripheral sector necrosis of the lenticule. At 10 months, the lenticule was removed with replacement by a second procedure which was successful.
A detailed study of epikeratoplasty performed without using sutures has not been previously reported. This report outlines results and complications using a sutureless technique with an oversize 9-millimeter lenticule. The surgical technique was similar to that used with the conventional procedure18,19 except for free lenticule edge tucking in the lamellar pocket, where no sutures were placed to anchor the oversize lenticule. The final placement of a bandage contact lens (Hydrocurve II 55% H2O content) was considered an essential part of the procedure, because the lenticule was thus further uniformly splinted into position and later protected from lid action.
No lenticule edge dislocation occurred after the lenticule had developed an intact epithelium. As Rostron and associates suggest,8 the lenticule tissue may undergo an increased degree of deturgescence with reepithelialization, and thus maintain its position by hydrostatic forces as well as by the normal healing process. The fact that lenticule edge dehiscence in the immediate postoperative period was limited to a small sector in all five cases points out that mechanical tissue forces may predispose the lenticule to maintain its tucked position as well as hydrostatic forces. Published studies of the conventional technique for epikeratoplasty have not implied there was a timed restriction for early suture removal when needed, nor is edge dislocation related to suture absence documented. At some specifically undefined postoperative period, all lenticules are adherent enough to maintain position without sutures until final fibrosis and healing takes place.
An 81.5% rate of lenticule adherence in this study points toward a combination of forces which predispose the lenticule to stay in position without anchoring sutures.
Visual acuities and refractive parameters for this limited study population showed comparative results to those obtained with a conventional technique. Astigmatic corneal changes were consistent with studies using a conventional sutured technique, showing no significant change over time.12'18,19 The patients beyond the influence of amblyopia who improved visual acuity may be explained, in part, by the patients increasing familiarization with the acuity exam process, along with increased motivation and cooperation as repeated exams were carried out. Our experience with a more rural population has shown familiarization to be a factor in changing and improved acuity levels. Neither change in astigmatism nor corneal tissue clarity were factors in their improved vision. This contradicts the experience ophthalmologists in more Western countries may have had, as some might assume adequate preoperative visual acuity testing was not performed preoperatively to determine best corrected acuity. This underlines the unique aspect of applying epikeratoplasty in more rural populations. Not only does acuity testing take on dimensions of an "educative process," but the probability of patients being able or willing to return for postoperative follow up is altered. Standards for routine follow up for possible suture irritation or removal simply do not apply in many other parts of the world. Normal alternatives of contact lenses cannot be maintained, changing the indications for surgery. Longer lead time, with possible amblyogenesis, is necessary in ordering and delivering the lenticule in the local environment. No-suture epikeratoplasty, in a less developed technological setting, may have numerous extenuating social-geographical circumstances to recommend the procedure, outweighing a closely observed higher rate of initial complication.
Figure 2: Clinical appearance 10 days after no-sufure epikeratoplasty. Note the oversize 9-millimeter lenticule, smooth healing, and wide buried tissue interface for adherence (between arrowheads).
No tendency for the oversize lenticule to be thrown into folds from mechanical pressure was noted, as in some myopic tissue lenticules.6,20 The larger lenticule edge overlap in the host tissue may expedite keratocyte repopulation due to the wider interface with host stroma.21 Histopathologic study of the one lens removed due to mechanical trauma showed keratocyte repopulation, but no definitive statement could be made of the comparative repopulation in relation to classical epikeratoplasty. The oversize lenticule creates a wider tissue interface for adherence at the edge, possibly increasing later resistance to dislocation from late mechanical trauma (Fig 2). The author now uses a 9-millimeter lenticule when applying sutures in epikeratoplasty and has noted no change in refractive results when compared to those obtained with an 8.5-millimeter lenticule.
A no-suture technique can result in significant benefits. The operative time for the patients in this study was significantly reduced, with the procedure routinely lasting only 20 minutes. Both surgical trauma and risk of retinal damage from the light of the operating microscope were reduced. Further anesthesia for suture removal in the pediatric age group was avoided, and postoperative management was simplified by avoiding the complications related to the suture-removal phase of epikeratoplasty. Suturing might be replaced by adding a biologic adhesive, or laser treatment, to the lenticule edge after it is tucked into position, as suggested in some studies. An even larger lenticule-host size disparity may reduce edge dislocation, but could produce a pool of unknown variables related to the excess lenticule tissue and host corneal nutrient demands. Eliminating all sutures can produce complications; with further modification of the operative procedure, nosuture epikeratoplasty may become a reliable and more attractive technique in the future.
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21. Yamaguchi T, Koenig SB, Kimuras T, et al. Histological study of epikeratophakia in primates. Ophthalmic Surg. 1984;15:230-235.