Epikeratophakia for Keratoconus

Eye (1990) 4, 531-534 Epikeratophakia for Keratoconus BREIT L. HALLIDAY London Summary Results of the author's first 15 cases of epikeratophakia for keratoconus are pre sented. All patients were intolerant of contact lens correction and could not achieve satisfactory acuity with spectacle correction due to corneal ectasia and irregular astigmatism. The average follow-up was 13 months. Seventy-three per cent of eyes treated had a pre-operative spectacle acuity of 6/60 or worse. One eye had a pre existing amblyopia that limited final acuity, but every other eye achieved a post operative spectacle acuity of 6/12 or better and 50% achieved 6/6. One eye had 11 dioptres of post-operative astigmatism and required penetrating keratoplasty; the remaining eyes had an average 'astigmatism of 1.9 dioptres. Epikeratophakia appears to be a safe alternative to penetrating keratoplasty in selected cases. Although most cases of keratoconus can be slow post-operative recovery of visual acuity successfully managed with spectacle or con and a slightly sub-optimal final visual acuity tact lens correction, a small proportion of due to the fact that the host cornea remains in patients require surgery to improve visual situ. acuity.! This paper presents the results from the first Penetrating keratoplasty is the most com 15 cases of epikeratophakia for keratoconus mon surgical procedure and ustially results in performed by the author. a clear graft and good visual acuity.2,3 Impor tant common complications of penetrating Patients and Methods keratoplasty include allograft rejection and Patient selection high residual astigmatism. More rarely, seri Patients were referred to the Corneal Clinic at ous complications such as primary graft fail Moorfields Eye Hospital where they were ure, endophthalmitis and glaucoma may assessed as potential candidates for surgery. occur. Epikeratophakia was only considered when Epikeratophakia is an alternative tech simpler alternatives were considered inappro nique that can be used in selected cases of ker priate. In every case spectacle correction was atoconus.4-7 The aim of surgery is to flatten impossible due to irregular astigmatism and the ectatic cornea and to eliminate irregular astigmatism. Compared to penetrating ker all patients were intolerant of hard contact atoplasty, epikeratophakia is less invasive, lenses. Every eye treated had marked corneal being essentially extraocular, and may there ectasia, but in no case was there any great fore be safer. Epikeratophakia has additional degree of central corneal scarring. potential advantages; rejection of the cryo lathed lenses does not occur and, as the host Lens manufacture cornea remains intact, astigmatism may be Lenses were manufactured by the author less of a post-operative problem. Potential using donor corneas supplied from Moorfields disadvantages of epikeratophakia include Eye Hospital Eye Bank. Only corneas that Correspondence to: B. L. Halliday FRCS, Moorfields Eye Hospital, City Road, London EC1V 2PD. 532 BREIT. L. HALLIDAY had been stored either in K-Sol or in pocket into the peripheral cornea from the McCarey-Kaufman storage media were used. base of the trephine cut. In general these corneas had been rejected as To minimise the possibility of residual epi suitable for penetrating keratoplasty by virtue thelial cells causing interface opacities, a cel of the age of donor, poor endothelial appear lulose swab, barely moistened with absolute ance or prolonged time in storage. A 9 mm alcohol, was then used to wipe the cornea disposable trephine was used to punch out, within the area of the trephine cut. The cor from the endothelial side, a corneal disc from nea was then washed thoroughly with a the donor cornea. stream of irrigating fluid. A specially developed cryolathe (City The epikeratophakia lens was then sutured crown Sales, 14 Kempston Close, Gatehouse in place with interrupted 9/0 nylon. Full tl1ick Way, Aylesbury, Buckinghamshire) was used ness bites were taken through the wing of the to manufacture the lenses. The lathe has a lens and the needle was then passed into the concave, 8 mm radius, aluminium base for the depth of pocket at the base of the trephina corneal disc which is cooled using carbon tion. The suture was tied very tightly to flatten dioxide to approximately -4 0° Celsius. At the ectatic cornea. For mild to moderate this temperature the cornea is frozen hard and amounts of keratoconus this suture tightening lathing becomes possible. The 9 mm corneal alone was sufficientto flatten the cornea. For disc was mounted on the lathe, frozen, and more marked keratoconus an assistant helped then machined with a diamond tipped cutting to flatten the cornea as the suture was tied by tool from the endothelial side. An 8 mm pressing on the cornea with a disposable irri radius of cut was used to give a parallel sided gating vectis (Steriseal 161925G). In every lens of thickness 0.5 mm. A 'wing' of thick case sufficient flattening of the cornea was ness 0.3 mm was then lathed on the peripheral achieved without the need to perform a part of the corneal disc to facilitate tucking of paracentesis. the lens into the corresponding pocket in the After the firsteight sutures were in place, a host cornea. cyclodialysis spatula was used to tuck the wing of the lens into the peripheral pocket. The Surgical Technique resulting corneal contour was then subjec An almost identical technique was used on all tively assessed using an operative kerato the patients. Surgery was performed under scope. Additional sutures were then added or general anaesthesia. Superior and inferior over-tight sutures removed, as required, in an rectus sutures were used only if the eye was attempt to minimise any suture induced not pointing vertically. astigmatism. Corneal epithelium was removed using a The procedure was completed with a sub D15 scalpel blade. A caliper, set to 7.5 mm, conjunctival injection of antibiotic and the eye was used to guide the area of epithelial remo was padded until the first dressing. val; peripheral corneal epithelium was left Patients were generally discharged on the intact to facilitate subsequent post-operative first post-operative day using chloramphen epithelial regeneration over the sutured epi icol 0.5% and prednisolone 0.3% eye drops keratophakia lens. Care was taken to ensure three times a day. Eyes were left unpadded that the scalpel blade did not pause as it swept and bandage contact lenses were not used. across the cornea as this can result in linear Sutures were left in place unless they become marks on Bowman's layer. loose or they appeared to be contributing to A 7 or 7.5 mm Hessburg-Baron suction high or irregular astigmatism. trephine was then used to make a circular cut in the host cornea to a depth of approximately Results 190 microns (turning the capstan by three One eye was treated in each of 15 patients one-quarter turns). whose average age was 25 years (range 16 to A 23 gauge hypodermic needle, mounted 42). Pre-operative spectacle acuities were with its tip bent to an angle of 90°, 1.5 mm generally very poor with 11 eyes (73%) having from the end, was then used to dissect a an acuity of 6/60 or worse. Further details are EPIKERATOPHAKIA FOR KERATOCONUS 533 given in Table I. The average length of fol the patient with just 0.5 dioptres of astigma low-up was 12.8 months. tism. Patient number three had two dioptres The majority of patients had an uneventful of astigmatism at three months after surgery post-operative course with rapid re-epithelial and all the sutures were removed. The astig isation of the epikeratophakia lens and with matism increased to five dioptres by five steadily improving lens clarity paralleled by months and to 11 dioptres by seven months. an improvement in corrected visual acuity. At this stage the lens was removed and sub The topical steroid and antibiotic drops were sequently penetrating keratoplasty was gradually tailed off and in no case were they performed. continued beyond six weeks. Table I shows the final refractions and There were few complications in the post visual acuities. For patient number three the operative period. In three cases it was necess figures given are for the refraction obtained ary to temporarily increase the dose of topical just before the epikeratophakia lens was steroids (up to six times a day) to control post removed. Patient eight was assumed to be operative inflammation. amblyopic; she had strabismus surgery at the At most clinic visits a Placido disc was used age of 18 months and had no recollection of to verify the corneal regularity and where good acuity in the operated eye. Unfortu possible this was checked with refraction. nately these facts were not appreciated prior Individual sutures were removed if they to epikeratophakia surgery. Of the remaining become loose, or if it was felt, on the basis of 14 patients, all achieved a post-operative the Placido reflex or the refraction, that they spectacle acuity of at least 6112, with 11 (78%) were contributing to a high astigmatism. It reaching 6/9 and seven (50%) managing 6/6. was not always possible to predict the effect of Excluding patient number three, the average individual suture removal. For example in astigmatism was 1. 9 dioptres. one case (patient number 11) an astigmatism Recovery of visual acuity after epikera of three dioptres was initially recorded. A tophakia is believed to be slow. The average suture was removed in an attempt to reduce time to achieve 6/12 acuity was 3.6 months this. The result was that the unopposed action and for the patients that reached 6/6 acuity, of the remaining sutures induced astigmatism, this was achieved by an average of 5.1 in the axis orthogonal to the initial astigma months.

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