Repeatability has been claimed to be one of the most significant advantages of aphakic epikeratophakia for those cases with unsatisfactory results.1,2 Although refractive changes may be induced in the recipient corneas by epikeratophakia,3 reintervention has been shown to be compatible with good refractive outcome.1,2 With the surgical technique employed up to date, a free interval is usually required between removal of the original epi-lens and repeat intervention, to allow stabilization of the corneal shape. At the time of repeat surgery, after removing the surface epithelium, the new epi-lens is sutured in the same peripheral corneal pocket used for the primary procedure. To prevent possible postoperative interface downgrowth, also the epithelium filling this pocket must be completely removed. However, because of both the relatively low magnification of the operating microscope and the difficult access to this site, such maneuver may result incomplete.
We describe a modified aphakic epikeratophakia technique, which eliminates this potential risk and proved successful in one patient undergoing a third epikeratophakia procedure after failure of the repeat procedure because of interface epithelial downgrowth.
A 69-year-old white female was referred to us in July 1989 because of unsatisfactory refractive result after aphakic epikeratophakia in her left eye. Visual acuity was 20/30 with a correction of + 13.00 sph -0.75 cyl X 180°, keratometry readings were 48.50 diopters at 180° and 51.00 D at 90°. Both the epikeratophakia lens and the recipient cornea were crystal clear; fundus examination did not show any abnormalities.
Epikeratophakia removal was performed on November 11, 1989, and vision recovered to 20/30 with a correction of + 13.00 sph - 2.00 cyl x 10° 3 months thereafter.
Figure 1 : Successful epikeratophakia surgery (third procedure) 4 months postoperatively. The optical zone of the new lenticule (5.00 mm in diameter) is evident centrally. Concentric to it is the scar of the old corneal pocket used for the previous two operations.
The patient underwent a second epikeratophakia procedure on March 23, 1990. After careful removal of the surface epithelium, the lenticule was sutured into the same peripheral corneal pocket used for the previous procedure. One month later, the patient was referred to us again because of the presence of a chronic epithelial defect. Slit-lamp microscopic examination revealed a hazy lenticule partly covered by epithelium. Melting of the bare portion was evident over a large area. The lenticule was directly removed at the slit-lamp microscope. A continuous epithelial layer was found under the lenticule, covering the entire recipient cornea. Two months after removal of the second lenticule, best corrected visual acuity was 20/60 and refraction had not changed from the values recorded after the first removal.
On August 8, 1990, a third aphakic epikeratophakia procedure was performed according to the modified technique described below, to prevent epithelial downgrowth. Four months postoperatively (Fig 1), visual acuity was 20/60 with a correction of + 1.50 sph -2.00 cyl x 10°. Keratometry readings were 59.50 D at 10° and over 60.00 D at 100°. Photokeratography (Fig 2) showed a regular corneal profile with minimal astigmatic error. The lenticule and the recipient cornea were clear; no anterior segment or fundus abnormalities could be seen. Best corrected visual acuity, refraction, as well as keratometric readings have remained stable up to the last examination time on July 10, 1991.
After inserting a Schott eyelid speculum, both the superior and the inferior recti were fixated with a 5-0 silk suture. A 4% cocaine solution was used to loosen the corneal epithelium from the underlying Bowman's layer. Then, the epithelium was mechanically removed with a blunt spatula over the central area delimited by the previous epikeratophakia circular incision (7.00 mm in diameter). A hand trephine, 5.00 mm in diameter, was used to perform a concentric incision reaching about half of the corneal thickness. A new corneal pocket was created by undermining the corneal tissue from the base of the incision toward the periphery, about 2.00 mm in length. To avoid penetration into the pocket used for the previous procedures, this dissection was performed at a deeper level (Fig 3). A standard aphakic epikeratophakia lenticule (8.50 mm in diameter), which had been rehydrated for about 20 minutes in a balanced salt solution containing gentamicin sulfate at a concentration of 150 µg/mL, was finally sutured in the corneal pocket using 12 interrupted 10-0 nylon sutures. At the end of surgery, a spatula was used to homogeneously spread the lenticule wing and avoid formation of folds. Corneal sphericity was checked by means of intraoperative keratometry, then gentamicin sulfate eyedrops were applied topically and dexamethasone phosphate as well as gentamicin sulfate were administered subconjunctivally.
Figure 2: Photokeratoscopic appearance corresponding to Figure 1 . A low amount of regular astigmatism with the rule is present.
Figure 3: Schematic representation of the modified epikeratophakia procedure used for repeat epikeratophakia surgery. The wing of the epikeratophakia lenticule (A) has been placed in a new corneal pocket obtained under that (B) used for two previous procedures.
Epithelial removal at the time of epikeratophakia surgery is a critical step to prevent postoperative interface downgrowth or cysts.4'5 This is usually accomplished by initially loosening the epithelium with a 4% cocaine solution and then mechanically removing it with a blunt spatula. However, clusters of cells may be left behind because of the relatively low magnification of the operating microscope. After removal of an epikeratophakia lenticule, the corneal peripheral pocket is filled with an epithelial plug, which is particularly difficult to remove when attempting reintervention, such as in the case reported herein.
To reduce the risk of a renewed downgrowth at the time of the third epikeratophakia procedure, a modified technique was used, which made epithelial removal from the peripheral corneal pocket unnecessary. Besides an increased risk of perforation while undermining the peripheral cornea at a deeper level, no other technical difficulties were involved in this type of procedure when compared to standard epikeratophakia.
Postoperatively, reepithelialization was not adversely affected and, despite the reduction in size of the optical zone, both minimal residual refractive error and useful vision could be obtained. Further evaluation in a larger number of patients undergoing repeat epikeratophakia surgery is needed to confirm the advantages of the new technique over the conventional one.
1. McDonald MB, Kaufman HE, Aquavella JV, et al. The nationwide study of epikeratophakia for aphakia in adults. Am J Ophthalmol. 1987;103:358-365.
2. Morgan KS, McDonald MB, Hiles DA, et al. The nationwide study of epikeratophakia for aphakia in children. Am J Ophthalmol. 1987:103:366-374.
3. Gilbert ML, Roth AS, Friedlander MH. Human corneal flattening by Hessburg-Barron annular trephination; an epikeratoplasty reversibility variable. ARVO Abstract. Invest Ophthalmol Vis Sci. 1988;29(suppl):391.
4. Frangieh GT, Kenyon KR, Wagoner MD, et al. Epithelial abnormalities and sterile ulceration of epikeratoplasty grafts. Ophthalmology. 1988;95:213-227.
5. Steinert RF, Grene RB. Postoperative management of epikeratoplasty. J Cataract Refract Surg. 1988;14:255-264.